<td>Under development: Not open for comment. Do not cite</td>
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<div id="abstract">
<h2>Abstract</h2>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">This adverse outcome pathway details the linkage between binding and activation of estrogen receptor as a nuclear transcription factor, primarily in oviparous male vertebrates, and a decrease in population growth. Estrogen receptors are ligand-dependent transcription factors that regulate gene transcription through estrogen response elements, allowing for the normal biological functions of estrogens (Klinge, 2001). However, various chemicals/classes of chemicals have been shown to act as ER agonists with the most potent being estradiol (E2) and ethinylestradiol (EE2) (Aarts et al., 2013). Numerous compounds including polycyclic aromatic hydrocarbons, chlorinated chemicals (e.g. PCBs), plasticizers (e.g. phthalates), and phenolic industrial chemicals (e.g., alkylphenols, parabens), and plant sterols also interact with ERα in vitro, with the potential to produce in vivo estrogenic effects (Ng et al., 2014; Pillon et al., 2005). A well characterized response to ER agonists involves hepatic production of vitellogenin (VTG; egg yolk precursor protein). Induction of <em>vtg </em>mRNA can result in elevated plasma VTG, particularly in oviparous male vertebrates, and can potentially cause downstream issues such as renal failure and morbidity. This AOP is relevant to both sexes, although more so to males as they do not produce VTG under normal conditions and have no mechanism for readily excreting the lipoprotein (Sumpter & Jobling, 1995). While many aspects of the biology underlying this AOP are largely conserved across oviparous vertebrates our, focus on KER between increased plasma VTG and increased renal pathology was on freshwater fish. Therefore, caution should be used in applying the whole of the AOP beyond freshwater fish species.</span></span></p>
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<div id="background">
<h3>Background</h3>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:12pt"><span style="background-color:white"><span style="font-size:11.0pt"><span style="color:#212529">The key events in this AOP are well defined in the literature, particularly the early events. While this AOP was initially entered into the wiki over ten years ago it was only entered as a set of place-holder pages for which a full weight of evidence assembly had not been conducted. Following studies conducted on estrogenic PFAS, described below, there was motivation to redevelop and update the AOP. </span></span></span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:12pt"><span style="background-color:white"><span style="font-size:11.0pt"><span style="color:#212529">Houck et al. (2021) used an in vitro high throughput platform to screen and categorize more than 140 structurally diverse PFAS based on their pathway-specific bioactivities including estrogenic activity. Villeneuve et al. (2023) confirmed the estrogenic activity of four diols identified by Houck et al. (2021) in 4 day <em>in vivo</em> experiment that evaluated expression of ER responsive genes in male fathead minnows. This led to the motivation to further evaluate FC10-diol, which showed the strongest response, using both male and female fathead minnows in a 21-day study. This study design allowed for the measurement of nearly all the key events within this AOP and allowed for linking activation of the ER to impacts on survival and reproduction in fish.</span></span></span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:12pt"><span style="background-color:white"><strong><span style="font-size:11.0pt"><span style="color:#212529">Sex</span></span></strong><span style="font-size:11.0pt"><span style="color:#212529">: Although this AOP is applicable to both sexes it is far more relevant for males. This is in part because females have an excretion pathway for vitellogenin - namely deposition into oocytes which are then released into the environment. Males lack that mechanism, and thus are more likely to accumulate protein that can cause kidney pathologies.</span></span></span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:12pt"><span style="background-color:white"><strong><span style="font-size:11.0pt"><span style="color:#212529">Life stages</span></span></strong><span style="font-size:11.0pt"><span style="color:#212529">: This AOP is applicable to all life stages following the differentiation of the liver and kidney. Larvae prior to liver and kidney differentiation should not be included.</span></span></span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:12pt"><span style="background-color:white"><strong><span style="font-size:11.0pt"><span style="color:#212529">Taxonomic</span></span></strong><span style="font-size:11.0pt"><span style="color:#212529">: The assumed taxonomic applicability domain of this AOP is oviparous vertebrates that synthesize yolk precursor proteins and have functional kidneys. </span></span></span></span></span></p>
<h3>Essentiality of the Key Events</h3>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Overall, the confidence in the supporting data for essentiality of KEs within the AOP is moderate. There is direct evidence of ER agonism leading to an increase in vitellogenin mRNA expression that is supported in multiple review articles (e.g., Matozzo et al., 2008; Palmer & Selcer, 1996; Verderame & Scudiero, 2017). Similarly, there is direct evidence <em>vtg</em> mRNA synthesis precedes increases in plasma VTG. Korte et al. (2000) observed<em> vtg</em> mRNA increase in the liver of male fathead minnows within 4 hours followed by plasma VTG increase within 16 hours of treatment. There is indirect evidence that increased plasma VTG can lead to downstream KE, renal pathology, as well as resulting in downstream AOs, mortality and decrease in population growth rate. Studies have shown that when large quantities of VTG are circulating it can lead to hyalin material accumulation in the kidneys which can cause significant pathology (e.g., Folmar et al., 2001; Herman & Kincaid, 1988). Because the kidneys perform a suite of physiological roles that are critical for organismal homeostasis including waste excretion, osmoregulation, and fluid homeostasis (Preuss, 1993), damage to the renal system, including damage caused by circulating VTG, can lead to a loss of renal functions such as decreased glomerular filtration rate or impaired clearance of waste products which can lead to mortality (McKee & Wingert, 2015). As survival rate is an obvious determinant of population size there is indirect evidence linking increased mortality to decrease in population growth rate.</span></span></p>
<h3>Weight of Evidence Summary</h3>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">The weight of evidence for each of the KERs comprising the AOP are ranked moderate to high. In particular the biological plausibility at the molecular and cellular level of the early key events is strong. <span style="color:#212529">The biological plausibility linking ER activation to increased <em>vtg</em> mRNA synthesis is high. Actions of endogenous and exogenous estrogens are mediated by the ER which is part of the nuclear receptor superfamily.</span> <span style="color:#212529">Binding to the ligand-binding domain (LBD) of the ER initiates a series of molecular events culminating in the modulation of genes. Transcription of <em>vtg</em> is regulated by estrogens and their interaction on ERs and under high estrogen stimulation the fold increase of<em> vtg</em> transcripts increases by orders of magnitude (Brock & Shapiro, 1983). Additionally, there is high biological plausibility linking increased <em>vtg</em> mRNA synthesis to increased plasma VTG. The liver is the primary source of VTG synthesis and production and after it is synthesized it is secreted into the blood (Wallace, 1985). Vitellogenin transcription and translation results in protein production although there is a delay between expression of <em>vtg</em> and actual production/detection of VTG (e.g., Korte et al. 2000). Although a precise quantitative relationship describing all steps of vitellogenesis transcription/translation has not been described there are models and statistical relationships that define quantitative relationships between circulating E2 concentrations and circulating VTG concentrations have been developed (Ankley et al., 2008; Li et al., 2011; Murphy et al., 2009; Murphy et al., 2005).</span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Some uncertainties regarding the connection between increased VTG availability and the increase in renal pathology remain, resulting in our weight of evidence call as moderate. <span style="color:#212529">However, there is evidence that when large quantities of VTG are circulating, hyalin material can accumulate in the kidneys which can cause significant pathology (Folmar et al., 2001; Herman & Kincaid, 1988; Palace et al., 2002). Additionally,</span> numerous studies have documented further renal pathology such as hemorrhages in kidney tubules, hypertrophy of tubular epithelia, accumulated eosinophilic material in renal tissue, and edema in the interstitium between kidney tubules (e.g., Folmar et al., 2001; Hahlbeck et al., 2004; Länge et al., 2001; Mihaich et al., 2012; Palace et al., 2002; Zha et al., 2007). In fish exposed to estrogenic compounds there can be excessive production of VTG, which leads to renal failure, and increases mortality in fish (Herman & Kincaid, 1988). Generally, the molecular mass of proteins in glomerular filtrate are lower than albumin but when proteins like VTG are deposited in the kidneys they cannot be resorbed and the excess protein can lead to glomerular rupturing or hemorrhaging (Tojo & Kinugasa, 2012). Ultimately these pathologies can cause acute renal failure resulting in mortality. As survival rate is an obvious determinant of population size and is included in population modeling to calculate long-term persistence of the population (e.g., Miller et al., 2020) there is a moderate weight of evidence linking increased mortality to decrease in population growth rate. Numerous factors have the potential to lead to declining populations <span style="color:#212529">(e.g., </span>increased mortality in <span style="color:#212529">the reproductive population, excessive mortality in larval population) however </span>there is considerable evidence to support the idea that ER agonism can ultimately lead to decrease in the population growth<span style="color:#212529">. A notable example exposed fathead minnows to low concentrations of 17α-ethynylestradiol (EE2) in the Experimental Lakes Area, Canada. Vitellogenin mRNA and plasma was significantly elevated and, after the second season of EE2 additions to the lake, the fathead minnow population collapsed due to loss of the </span>young-of-the-year (Kidd et al., 2007; Palace et al., 2002). Overall, there is considerable evidence to support the idea that ER agonism can ultimately lead to decrease in the population growth rate. Overall weight of evidence is moderate.</span></span></p>
<p> </p>
<p> </p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><span style="background-color:white"><strong><span style="color:#212529">Uncertainties, inconsistencies, and data gaps</span></strong></span></span></span></p>
<ul>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><span style="background-color:white"><span style="color:#212529">Uncertainties related to MIE: Some uncertainty remains regarding which ER subtype(s) regulates vitellogenin gene expression in the liver of fish. In general, the literature suggests a close interplay between several ER subtypes in the regulation of vitellogenesis. Consequently, at present, the AOP is generalized to impacts on all ER subtypes, even though it remains possible that impacts on a particular sub-type may drive the adverse response.</span></span></span></span>
<ul style="list-style-type:circle">
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><span style="background-color:white"><span style="color:#212529">Using selective agonists and antagonists for ERα and ERβ, it was concluded that ERβ was primarily responsible for inducing vitellogenin production in rainbow trout and that compounds exhibiting ERα selectivity would not be detected using a vitellogenin ELISA bioassay (Leaños-Castañeda & Van Der Kraak, 2007). However, a subsequent study conducted in tilapia concluded that agonistic and antagonistic characteristics of mammalian, isoform-specific ER agonists and antagonists, cannot be reliably extrapolated to piscine ERs (Davis et al., 2010).</span></span></span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><span style="color:#212529">Based on RNA interference knock-down experiments Nelson and Habibi (Nelson & Habibi, 2010) proposed a model in which all ER subtypes are involved in E2-mediated vitellogenesis, with ERβ isoforms stimulating expression of both vitellogenin and ERα gene expression, and ER<a name="_Hlk181187559">α</a> helping to drive vitellogenesis, particularly as it becomes more abundant following sensitization.</span></span></span></li>
</ul>
</li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><span style="color:#212529">Uncertainties related to cause of renal pathology: Although the accumulation of hyalin material/lipoprotein within the kidneys has been confirmed to be partially caused by accumulated VTG, some of the accumulated proteins do not respond to VTG antibody (e.g., Folmar et al., 2001). Because male fish will also express other estrogen inducible proteins such as vitelline envelope and zona radiata some renal pathology could be caused by these related proteins rather than VTG (Johan Hyllner et al., 1994; Oppen‐Berntsen et al., 1994).</span></span></span>
<ul style="list-style-type:circle">
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><span style="color:#212529">Proliferative kidney disease (PKD) in fish caused by the parasite <em>Tetracapsuloides bryosalmonae</em> results in significant kidney pathology. However, when PKD infection took place under simultaneous exposure to EE2, kidney pathology was less pronounced even though hepatic vtg was elevated in fish exposed to the estrogen (Bailey et al., 2019; Rehberger et al., 2020).</span></span></span></li>
</ul>
</li>
</ul>
<h3>Quantitative Consideration</h3>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:12pt"><span style="background-color:white"><span style="font-size:11.0pt"><span style="color:#212529">Overall, the quantitative understanding for this AOP is low. Presently there is insufficient data to develop a quantitative AOP linking ER activation to mortality and decreased population growth rate. However, a 21-day reproductive study to estrogenic PFAS, FC10-diol, which allowed for the measurement of nearly all the key events within this AOP and allowed for linking activation of the ER to impacts on survival and reproduction in fish (Ankley et al. in prep). </span></span></span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:12pt"><span style="background-color:white"><span style="font-size:11.0pt"><span style="color:#212529">Increase in <em>vtg</em> synthesis leading to increase in plasma VTG was scored as having a moderate quantitative understanding due to the well-defined relationship between gene expression and protein synthesis. However, because the delay between expression of <em>vtg</em> and production/detection of VTG is not well defined our understanding is still limited.</span></span></span></span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Aarts, J. M. M. J. G., Wang, S., Houtman, R., van Beuningen, R. M. G. J., Westerink, W. M. A., Van De Waart, B. J., Rietjens, I. M. C. M., & Bovee, T. F. H. (2013). Robust Array-Based Coregulator Binding Assay Predicting ERα-Agonist Potency and Generating Binding Profiles Reflecting Ligand Structure. <em>Chemical Research in Toxicology</em>,<em> 26</em>(3), 336-346. <a href="https://doi.org/10.1021/tx300463b" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1021/tx300463b</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Ankley, G. T., Miller, D. H., Jensen, K. M., Villeneuve, D. L., & Martinović, D. (2008). Relationship of plasma sex steroid concentrations in female fathead minnows to reproductive success and population status. <em>Aquatic Toxicology</em>,<em> 88</em>(1), 69-74. <a href="https://doi.org/https:/doi.org/10.1016/j.aquatox.2008.03.005" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.aquatox.2008.03.005</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Bailey, C., von Siebenthal, E. W., Rehberger, K., & Segner, H. (2019). Transcriptomic analysis of the impacts of ethinylestradiol (EE2) and its consequences for proliferative kidney disease outcome in rainbow trout (Oncorhynchus mykiss). <em>Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology</em>,<em> 222</em>, 31-48. <a href="https://doi.org/https:/doi.org/10.1016/j.cbpc.2019.04.009" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.cbpc.2019.04.009</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Brock, M. L., & Shapiro, D. (1983). Estrogen regulates the absolute rate of transcription of the Xenopus laevis vitellogenin genes. <em>Journal of Biological Chemistry</em>,<em> 258</em>(9), 5449-5455. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Davis, L., Katsu, Y., Iguchi, T., Lerner, D., Hirano, T., & Grau, E. (2010). Transcriptional activity and biological effects of mammalian estrogen receptor ligands on three hepatic estrogen receptors in Mozambique tilapia. <em>The Journal of steroid biochemistry and molecular biology</em>,<em> 122</em>(4), 272-278. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Folmar, L. C., Gardner, G. R., Schreibman, M. P., Magliulo-Cepriano, L., Mills, L. J., Zaroogian, G., Gutjahr-Gobell, R., Haebler, R., Horowitz, D. B., & Denslow, N. D. (2001). Vitellogenin-induced pathology in male summer flounder (Paralichthys dentatus). <em>Aquatic Toxicology</em>,<em> 51</em>(4), 431-441. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Hahlbeck, E., Katsiadaki, I., Mayer, I., Adolfsson-Erici, M., James, J., & Bengtsson, B.-E. (2004). The juvenile three-spined stickleback (Gasterosteus aculeatus L.) as a model organism for endocrine disruption II—kidney hypertrophy, vitellogenin and spiggin induction. <em>Aquatic Toxicology</em>,<em> 70</em>(4), 311-326. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Herman, R. L., & Kincaid, H. L. (1988). Pathological effects of orally administered estradiol to rainbow trout. <em>Aquaculture</em>,<em> 72</em>(1-2), 165-172. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Houck, K. A., Patlewicz, G., Richard, A. M., Williams, A. J., Shobair, M. A., Smeltz, M., Clifton, M. S., Wetmore, B., Medvedev, A., & Makarov, S. (2021). Bioactivity profiling of per- and polyfluoroalkyl substances (PFAS) identifies potential toxicity pathways related to molecular structure. <em>Toxicology</em>,<em> 457</em>, 152789. <a href="https://doi.org/https:/doi.org/10.1016/j.tox.2021.152789" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.tox.2021.152789</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Johan Hyllner, S., Silvers, C., & Haux, C. (1994). Formation of the vitelline envelope precedes the active uptake of vitellogenin during oocyte development in the rainbow trout, Oncorhynchus mykiss. <em>Molecular Reproduction and Development</em>,<em> 39</em>(2), 166-175. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Kidd, K. A., Blanchfield, P. J., Mills, K. H., Palace, V. P., Evans, R. E., Lazorchak, J. M., & Flick, R. W. (2007). Collapse of a fish population after exposure to a synthetic estrogen. <em>Proceedings of the National Academy of Sciences</em>,<em> 104</em>(21), 8897-8901. <a href="https://doi.org/doi:10.1073/pnas.0609568104" style="color:#0563c1; text-decoration:underline">https://doi.org/doi:10.1073/pnas.0609568104</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Klinge, C. M. (2001). Estrogen receptor interaction with estrogen response elements. <em>Nucleic Acids Res</em>,<em> 29</em>(14), 2905-2919. <a href="https://doi.org/10.1093/nar/29.14.2905" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1093/nar/29.14.2905</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Länge, R., Hutchinson, T. H., Croudace, C. P., Siegmund, F., Schweinfurth, H., Hampe, P., Panter, G. H., & Sumpter, J. P. (2001). Effects of the synthetic estrogen 17α‐ethinylestradiol on the life‐cycle of the fathead minnow (Pimephales promelas). <em>Environmental Toxicology and Chemistry: An International Journal</em>,<em> 20</em>(6), 1216-1227. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Leaños-Castañeda, O., & Van Der Kraak, G. (2007). Functional characterization of estrogen receptor subtypes, ERα and ERβ, mediating vitellogenin production in the liver of rainbow trout. <em>Toxicology and applied pharmacology</em>,<em> 224</em>(2), 116-125. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Li, Z., Kroll, K. J., Jensen, K. M., Villeneuve, D. L., Ankley, G. T., Brian, J. V., Sepúlveda, M. S., Orlando, E. F., Lazorchak, J. M., Kostich, M., Armstrong, B., Denslow, N. D., & Watanabe, K. H. (2011). A computational model of the hypothalamic - pituitary - gonadal axis in female fathead minnows (Pimephales promelas) exposed to 17α-ethynylestradiol and 17β-trenbolone. <em>BMC Systems Biology</em>,<em> 5</em>(1), 63. <a href="https://doi.org/10.1186/1752-0509-5-63" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1186/1752-0509-5-63</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Matozzo, V., Gagné, F., Marin, M. G., Ricciardi, F., & Blaise, C. (2008). Vitellogenin as a biomarker of exposure to estrogenic compounds in aquatic invertebrates: A review. <em>Environment International</em>,<em> 34</em>(4), 531-545. <a href="https://doi.org/https:/doi.org/10.1016/j.envint.2007.09.008" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.envint.2007.09.008</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">McKee, R. A., & Wingert, R. A. (2015). Zebrafish Renal Pathology: Emerging Models of Acute Kidney Injury. <em>Current Pathobiology Reports</em>,<em> 3</em>(2), 171-181. <a href="https://doi.org/10.1007/s40139-015-0082-2" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1007/s40139-015-0082-2</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Mihaich, E., Rhodes, J., Wolf, J., van der Hoeven, N., Dietrich, D., Hall, A. T., Caspers, N., Ortego, L., Staples, C., & Dimond, S. (2012). Adult fathead minnow, Pimephales promelas, partial life‐cycle reproductive and gonadal histopathology study with bisphenol A. <em>Environmental toxicology and chemistry</em>,<em> 31</em>(11), 2525-2535. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Murphy, C. A., Rose, K. A., Rahman, M. S., & Thomas, P. (2009). Testing and applying a fish vitellogenesis model to evaluate laboratory and field biomarkers of endocrine disruption in Atlantic croaker (Micropogonias undulatus) exposed to hypoxia. <em>Environmental toxicology and chemistry</em>,<em> 28</em>(6), 1288-1303. <a href="https://doi.org/https:/doi.org/10.1897/08-304.1" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1897/08-304.1</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Murphy, C. A., Rose, K. A., & Thomas, P. (2005). Modeling vitellogenesis in female fish exposed to environmental stressors: predicting the effects of endocrine disturbance due to exposure to a PCB mixture and cadmium. <em>Reproductive Toxicology</em>,<em> 19</em>(3), 395-409. <a href="https://doi.org/https:/doi.org/10.1016/j.reprotox.2004.09.006" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.reprotox.2004.09.006</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Nelson, E. R., & Habibi, H. R. (2010). Functional Significance of Nuclear Estrogen Receptor Subtypes in the Liver of Goldfish. <em>Endocrinology</em>,<em> 151</em>(4), 1668-1676. <a href="https://doi.org/10.1210/en.2009-1447" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1210/en.2009-1447</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Ng, H. W., Perkins, R., Tong, W., & Hong, H. (2014). Versatility or Promiscuity: The Estrogen Receptors, Control of Ligand Selectivity and an Update on Subtype Selective Ligands. <em>International Journal of Environmental Research and Public Health</em>,<em> 11</em>(9), 8709-8742. <a href="https://www.mdpi.com/1660-4601/11/9/8709" style="color:#0563c1; text-decoration:underline">https://www.mdpi.com/1660-4601/11/9/8709</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Oppen‐Berntsen, D., Olsen, S., Rong, C., Taranger, G., Swanson, P., & Walther, B. (1994). Plasma levels of eggshell zr‐proteins, estradiol‐17β, and gonadotropins during an annual reproductive cycle of Atlantic salmon (Salmo salar). <em>Journal of Experimental Zoology</em>,<em> 268</em>(1), 59-70. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Palace, V. P., Evans, R. E., Wautier, K., Baron, C., Vandenbyllardt, L., Vandersteen, W., & Kidd, K. (2002). Induction of vitellogenin and histological effects in wild fathead minnows from a lake experimentally treated with the synthetic estrogen, ethynylestradiol. <em>Water Quality Research Journal</em>,<em> 37</em>(3), 637-650. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Palmer, B. D., & Selcer, K. W. (1996). Vitellogenin as a biomarker for xenobiotic estrogens: a review. <em>Environmental Toxicology and Risk Assessment: Biomarkers and Risk Assessment: Fifth Volume</em>, 3-22. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Pillon, A., Boussioux, A.-M., Escande, A., Aït-Aïssa, S., Gomez, E., Fenet, H., Ruff, M., Moras, D., Vignon, F., & Duchesne, M.-J. (2005). Binding of estrogenic compounds to recombinant estrogen receptor-α: application to environmental analysis. <em>Environmental Health Perspectives</em>,<em> 113</em>(3), 278-284. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Preuss, H. G. (1993). Basics of renal anatomy and physiology. <em>Clinics in laboratory medicine</em>,<em> 13</em>(1), 1-11. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Rehberger, K., Wernicke von Siebenthal, E., Bailey, C., Bregy, P., Fasel, M., Herzog, E. L., Neumann, S., Schmidt-Posthaus, H., & Segner, H. (2020). Long-term exposure to low 17α-ethinylestradiol (EE2) concentrations disrupts both the reproductive and the immune system of juvenile rainbow trout, Oncorhynchus mykiss. <em>Environment International</em>,<em> 142</em>, 105836. <a href="https://doi.org/https:/doi.org/10.1016/j.envint.2020.105836" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.envint.2020.105836</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Sumpter, J. P., & Jobling, S. (1995). Vitellogenesis as a biomarker for estrogenic contamination of the aquatic environment. <em>Environmental Health Perspectives</em>,<em> 103</em>(suppl 7), 173-178. <a href="https://doi.org/10.1289/ehp.95103s7173" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1289/ehp.95103s7173</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Tojo, A., & Kinugasa, S. (2012). Mechanisms of glomerular albumin filtration and tubular reabsorption. <em>Int J Nephrol</em>,<em> 2012</em>, 481520. <a href="https://doi.org/10.1155/2012/481520" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1155/2012/481520</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Verderame, M., & Scudiero, R. (2017). Estrogen-dependent, extrahepatic synthesis of vitellogenin in male vertebrates: A mini-review. <em>Comptes Rendus Biologies</em>,<em> 340</em>(3), 139-144. <a href="https://doi.org/https:/doi.org/10.1016/j.crvi.2017.01.005" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.crvi.2017.01.005</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Villeneuve, D. L., Blackwell, B. R., Cavallin, J. E., Collins, J., Hoang, J. X., Hofer, R. N., Houck, K. A., Jensen, K. M., Kahl, M. D., Kutsi, R. N., Opseth, A. S., Santana Rodriguez, K. J., Schaupp, C., Stacy, E. H., & Ankley, G. T. (2023). Verification of In Vivo Estrogenic Activity for Four Per- and Polyfluoroalkyl Substances (PFAS) Identified as Estrogen Receptor Agonists via New Approach Methodologies. <em>Environmental Science & Technology</em>,<em> 57</em>(9), 3794-3803. <a href="https://doi.org/10.1021/acs.est.2c09315" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1021/acs.est.2c09315</a> </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Wallace, R. A. (1985). Vitellogenesis and oocyte growth in nonmammalian vertebrates. <em>Oogenesis</em>, 127-177. </span></span></p>
<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">Zha, J., Wang, Z., Wang, N., & Ingersoll, C. (2007). Histological alternation and vitellogenin induction in adult rare minnow (Gobiocypris rarus) after exposure to ethynylestradiol and nonylphenol. <em>Chemosphere</em>,<em> 66</em>(3), 488-495. </span></span></p>
<td><a href="/aops/29">Aop:29 - Estrogen receptor agonism leading to reproductive dysfunction</a></td>
<td>MolecularInitiatingEvent</td>
</tr>
<tr>
<td><a href="/aops/52">Aop:52 - ER agonism leading to skewed sex ratios due to altered sexual differentiation in males</a></td>
<td>MolecularInitiatingEvent</td>
</tr>
<tr>
<td><a href="/aops/53">Aop:53 - ER agonism leading to reduced survival due to renal failure</a></td>
<td>MolecularInitiatingEvent</td>
</tr>
<tr>
<td><a href="/aops/536">Aop:536 - Estrogen receptor agonism leading to reduced survival and population growth due to renal failure</a></td>
<td>MolecularInitiatingEvent</td>
</tr>
<tr>
<td><a href="/aops/537">Aop:537 - Estrogen receptor agonism leads to reduced fecundity via increased vitellogenin in the liver</a></td>
<td>MolecularInitiatingEvent</td>
</tr>
<tr>
<td><a href="/aops/112">Aop:112 - Increased dopaminergic activity leading to endometrial adenocarcinomas (in Wistar rat)</a></td>
<td>KeyEvent</td>
</tr>
<tr>
<td><a href="/aops/200">Aop:200 - Estrogen receptor activation leading to breast cancer </a></td>
<td>MolecularInitiatingEvent</td>
</tr>
<tr>
<td><a href="/aops/167">Aop:167 - Early-life estrogen receptor agonism leading to endometrial adenosquamous carcinoma via promotion of sine oculis homeobox 1 progenitor cells</a></td>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><a name="_Hlk165971069"><span style="color:#333399"><strong>Taxonomic applicability:</strong></span></a><span style="color:#333399"> In mammals there are two ER subtypes, ER alpha (ERα) and ER beta (ERβ), which are located on chromosome 6 and 14 and encoded by two different genes (ESR1 and ESR2) <a name="_Hlk162433655"></a>(Ascenzi et al., 2006). ERs were conventionally identified as mammal specific, but most vertebrates contain functional ERs. However, although teleost fish have receptors homologous to mammilian ERα, ERβ is divided into ERβ1 and ERβ2 resulting in three distinct ERs (Asnake et al., 2019; Menuet et al., 2004; Menuet et al., 2002). The majority of invertebrates (i.e. mollusks) possess a gene that is the orthologue of the vertebrate ER but in many species it has been demonstrated to only have constitutive transcriptional activity, and is not activated by ligand binding (Balbi et al., 2019). However, ERs in annelids share functional characteristics with vertebrate ERs and its transcriptional activity can be disrupted by known endocrine-disrupting substances (Keay & Thornton, 2009). </span></span></span></p>
<p><a name="_Hlk165971069">Taxonomic applicability:</a> In mammals there are two ER subtypes, ER alpha (ERα) and ER beta (ERβ), which are located on chromosome 6 and 14 and encoded by two different genes (ESR1 and ESR2) <a name="_Hlk162433655"></a>(Ascenzi et al., 2006). ERs were conventionally identified as mammal specific, but most vertebrates contain functional ERs. However, although teleost fish have receptors homologous to mammilian ERα, ERβ is divided into ERβ1 and ERβ2 resulting in three distinct ERs (Asnake et al., 2019; Menuet et al., 2004; Menuet et al., 2002). The majority of invertebrates (i.e. mollusks) possess a gene that is the orthologue of the vertebrate ER but in many species it has been demonstrated to only have constitutive transcriptional activity, and is not activated by ligand binding (Balbi et al., 2019). However, ERs in annelids share functional characteristics with vertebrate ERs and its transcriptional activity can be disrupted by known endocrine-disrupting substances (Keay & Thornton, 2009).</p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>This MIE would generally be viewed as relevant to vertebrates, but not invertebrates.</strong></span></span></span></p>
<p>This event would generally be viewed as relevant to vertebrates, but not invertebrates.</p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><a name="_Hlk165905099"><span style="color:#333399"><strong>Life stage:</strong></span></a><a name="_Hlk165899451"><span style="color:#333399"><strong> </strong></span></a><span style="color:#333399">This MIE is applicable to all life stages.</span></span></span></p>
<p><a name="_Hlk165905099">Life stage:</a><a name="_Hlk165899451"> </a>This event is applicable to all life stages.</p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Sex: </strong>This MIE is applicable to both sexes.</span></span></span></p>
<p>Sex: This event is applicable to both sexes.</p>
<h4>Key Event Description</h4>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><span style="color:#333399"><strong>Site of action:</strong> The molecular site of action is the estrogen receptor (ER). ERs </span><a name="_Hlk162335835"><span style="color:#333399">are members of the steroid hormone receptor family which belongs to a group of nuclear receptors </span></a><span style="color:#333399">that are transcriptionally activated by ligands leading to downstream activation of many cellular processes. ERs are composed of three principal domains – N-terminal domain (NTD), DNA binding domain (DBD), and the ligand binding domain (LBD). ER binds to specific DNA sequences known as estrogen response elements (EREs); EREs are generally short sequences located in the promoter region but can also exist in introns or exons (Klinge, 2001). ER-mediated gene transcription is initiated by binding of the DBD to an ERE with two distinct transcriptional activation domains, AF1 and AF2, located on the NTD and LBD respectively (Kumar et al., 2011).</span></span></span></p>
<p>Site of action: The molecular site of action is the estrogen receptor (ER). ERs <a name="_Hlk162335835">are members of the steroid hormone receptor family which belongs to a group of nuclear receptors </a>that are transcriptionally activated by ligands leading to downstream activation of many cellular processes. ERs are composed of three principal domains – N-terminal domain (NTD), DNA binding domain (DBD), and the ligand binding domain (LBD). ER binds to specific DNA sequences known as estrogen response elements (EREs); EREs are generally short sequences located in the promoter region but can also exist in introns or exons (Klinge, 2001). ER-mediated gene transcription is initiated by binding of the DBD to an ERE with two distinct transcriptional activation domains, AF1 and AF2, located on the NTD and LBD respectively (Kumar et al., 2011).</p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Responses at the macromolecular level:</strong> </span><span style="font-size:11pt">ER’s bind to endogenous and exogenous compounds and are activated by endogenous ligands such as estrone (E1), estradiol (E2) and estriol (E3) (Ng et al., 2014). There are numerous compounds (e.g., natural or pharmaceutical estrogens, alkylphenols, organochlorine pesticides, phthalates, etc.) that can act as estrogen agonists or antagonists, and effectively mimic or block the natural effects of estrogens on the ER (Pillon et al., 2005; Schmieder et al., 2014).</span></span></span></p>
<p>Responses at the macromolecular level:ER’s bind to endogenous and exogenous compounds and are activated by endogenous ligands such as estrone (E1), estradiol (E2) and estriol (E3) (Ng et al., 2014). There are numerous compounds (e.g., natural or pharmaceutical estrogens, alkylphenols, organochlorine pesticides, phthalates, etc.) that can act as estrogen agonists or antagonists, and effectively mimic or block the natural effects of estrogens on the ER (Pillon et al., 2005; Schmieder et al., 2014).</p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">ER is part of a multi-protein complex consisting of HSP 90, HSP 70, and immunophilins (Stice & Knowlton, 2008). In this multi-protein complex HSP 90 is the dominant protein and its binding to ER is essential for ER conformational binding of 17β-estradiol (Segnitz & Gehring, 1997). When binding on the LBD receptor occurs ER dissociates from HSP 90 and leads to receptor dimerization which can either be homodimers from the same isoform (ERα-Erα) or heterodimers containing one unit from both isoforms (ERα-Erβ) (Fliss et al., 2000). The translocation of these dimers into the nucleus modulates gene transcription (Aranda & Pascual, 2001).</span></span></span></p>
<p>ER is part of a multi-protein complex consisting of HSP 90, HSP 70, and immunophilins (Stice & Knowlton, 2008). In this multi-protein complex HSP 90 is the dominant protein and its binding to ER is essential for ER conformational binding of 17β-estradiol (Segnitz & Gehring, 1997). When binding on the LBD receptor occurs ER dissociates from HSP 90 and leads to receptor dimerization which can either be homodimers from the same isoform (ERα-Erα) or heterodimers containing one unit from both isoforms (ERα-Erβ) (Fliss et al., 2000). The translocation of these dimers into the nucleus modulates gene transcription (Aranda & Pascual, 2001).</p>
<h4>How it is Measured or Detected</h4>
<ul>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">OECD Test No. 455: Performance-based test guideline for stably transfected transactivation in vitro assays to detect estrogen receptor agonists and antagonists (OECD 2021).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">OECD Test No. 457: BG1Luc Estrogen Receptor Transactivation Test Method for Identifying Estrogen Receptor Agonists and Antagonists (OECD 2012).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Standard Evaluation Procedure (SEP) for estrogen receptor transcriptional activation (Human Cell Line HeLa-9903) assay was developed by the U.S. Environmental Protection Agency (EPA).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">ER-based transactivation assays that have been used to detect ER agonists and antagonist using cell lines include T47D-Kbluc assay (Wehmas et al., 2011), the ERα CALUX assay (Van et al.); MELN assay (Berckmans et al., 2007); and the yeast estrogen screen (YES; (De Boever et al., 2001)). The T47D-Kbluc assay responds to both ERα and ERß agonists but support the assumption that ERα is inducing more reporter expression than ERß. Each of these assays have undergone some level of validation.</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Browne et al. (2015) integrated 18 ER ToxCast high-throughput screening (HTS) assays, measuring ER binding, dimerization, chromatin binding, transcriptional activation and ER-dependent cell proliferation, into the ToxCast ER pathway model. This mathematical model that in vitro assays to predict whether a chemical is an ER agonist or antagonist.</span></span></span></li>
<li>OECD Test No. 455: Performance-based test guideline for stably transfected transactivation in vitro assays to detect estrogen receptor agonists and antagonists (OECD 2021).</li>
<li>OECD Test No. 457: BG1Luc Estrogen Receptor Transactivation Test Method for Identifying Estrogen Receptor Agonists and Antagonists (OECD 2012).</li>
<li>Standard Evaluation Procedure (SEP) for estrogen receptor transcriptional activation (Human Cell Line HeLa-9903) assay was developed by the U.S. Environmental Protection Agency (EPA).</li>
<li>ER-based transactivation assays that have been used to detect ER agonists and antagonist using cell lines include T47D-Kbluc assay (Wehmas et al., 2011), the ERα CALUX assay (Van et al.); MELN assay (Berckmans et al., 2007); and the yeast estrogen screen (YES; (De Boever et al., 2001)). The T47D-Kbluc assay responds to both ERα and ERß agonists but support the assumption that ERα is inducing more reporter expression than ERß. Each of these assays have undergone some level of validation.</li>
<li>Browne et al. (2015) integrated 18 ER ToxCast high-throughput screening (HTS) assays, measuring ER binding, dimerization, chromatin binding, transcriptional activation and ER-dependent cell proliferation, into the ToxCast ER pathway model. This mathematical model that in vitro assays to predict whether a chemical is an ER agonist or antagonist.</li>
<li>OECD Test No. 440: Uterotrophic Bioassay in Rodents: A Short-Term Screenign Test for Oestrogenic Properties. OCED Publishing. 2018. has been used to detect in vivo estrogenic activity.</li>
</ul>
<h4>References</h4>
<ul>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Aranda, A., & Pascual, A. (2001). Nuclear hormone receptors and gene expression. <em>Physiological reviews</em>,<em> 81</em>(3), 1269-1304. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Ascenzi, P., Bocedi, A., & Marino, M. (2006). Structure–function relationship of estrogen receptor α and β: Impact on human health. <em>Molecular aspects of medicine</em>,<em> 27</em>(4), 299-402. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Asnake, S., Modig, C., & Olsson, P.-E. (2019). Species differences in ligand interaction and activation of estrogen receptors in fish and human. <em>The Journal of steroid biochemistry and molecular biology</em>,<em> 195</em>, 105450. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Balbi, T., Ciacci, C., & Canesi, L. (2019). Estrogenic compounds as exogenous modulators of physiological functions in molluscs: Signaling pathways and biological responses. <em>Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology</em>,<em> 222</em>, 135-144. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Berckmans, P., Leppens, H., Vangenechten, C., & Witters, H. (2007). Screening of endocrine disrupting chemicals with MELN cells, an ER-transactivation assay combined with cytotoxicity assessment. <em>Toxicology in vitro</em>,<em> 21</em>(7), 1262-1267. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Browne, P., Judson, R. S., Casey, W. M., Kleinstreuer, N. C., & Thomas, R. S. (2015). Screening Chemicals for Estrogen Receptor Bioactivity Using a Computational Model. <em>Environmental Science & Technology</em>,<em> 49</em>(14), 8804-8814. <a href="https://doi.org/10.1021/acs.est.5b02641" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1021/acs.est.5b02641</a> </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">De Boever, P., Demaré, W., Vanderperren, E., Cooreman, K., Bossier, P., & Verstraete, W. (2001). Optimization of a yeast estrogen screen and its applicability to study the release of estrogenic isoflavones from a soygerm powder. <em>Environmental Health Perspectives</em>,<em> 109</em>(7), 691-697. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Fliss, A. E., Benzeno, S., Rao, J., & Caplan, A. J. (2000). Control of estrogen receptor ligand binding by Hsp90. <em>The Journal of steroid biochemistry and molecular biology</em>,<em> 72</em>(5), 223-230. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Keay, J., & Thornton, J. W. (2009). Hormone-activated estrogen receptors in annelid invertebrates: implications for evolution and endocrine disruption. <em>Endocrinology</em>,<em> 150</em>(4), 1731-1738. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Klinge, C. M. (2001). Estrogen receptor interaction with estrogen response elements. <em>Nucleic Acids Res</em>,<em> 29</em>(14), 2905-2919. <a href="https://doi.org/10.1093/nar/29.14.2905" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1093/nar/29.14.2905</a> </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Kumar, R., Zakharov, M. N., Khan, S. H., Miki, R., Jang, H., Toraldo, G., Singh, R., Bhasin, S., & Jasuja, R. (2011). The dynamic structure of the estrogen receptor. <em>Journal of amino acids</em>,<em> 2011</em>. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Menuet, A., Le Page, Y., Torres, O., Kern, L., Kah, O., & Pakdel, F. (2004). Analysis of the estrogen regulation of the zebrafish estrogen receptor (ER) reveals distinct effects of ERalpha, ERbeta1 and ERbeta2. <em>Journal of Molecular Endocrinology</em>,<em> 32</em>(3), 975-986. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Menuet, A., Pellegrini, E., Anglade, I., Blaise, O., Laudet, V., Kah, O., & Pakdel, F. (2002). Molecular characterization of three estrogen receptor forms in zebrafish: binding characteristics, transactivation properties, and tissue distributions. <em>Biology of reproduction</em>,<em> 66</em>(6), 1881-1892. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Ng, H. W., Perkins, R., Tong, W., & Hong, H. (2014). Versatility or Promiscuity: The Estrogen Receptors, Control of Ligand Selectivity and an Update on Subtype Selective Ligands. <em>International Journal of Environmental Research and Public Health</em>,<em> 11</em>(9), 8709-8742. <a href="https://www.mdpi.com/1660-4601/11/9/8709" style="color:#0563c1; text-decoration:underline">https://www.mdpi.com/1660-4601/11/9/8709</a> </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Pillon, A., Boussioux, A.-M., Escande, A., Aït-Aïssa, S., Gomez, E., Fenet, H., Ruff, M., Moras, D., Vignon, F., & Duchesne, M.-J. (2005). Binding of estrogenic compounds to recombinant estrogen receptor-α: application to environmental analysis. <em>Environmental Health Perspectives</em>,<em> 113</em>(3), 278-284. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Schmieder, P. K., Kolanczyk, R. C., Hornung, M. W., Tapper, M. A., Denny, J. S., Sheedy, B. R., & Aladjov, H. (2014). A rule-based expert system for chemical prioritization using effects-based chemical categories. <em>SAR and QSAR in Environmental Research</em>,<em> 25</em>(4), 253-287. <a href="https://doi.org/10.1080/1062936X.2014.898691" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1080/1062936X.2014.898691</a> </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Segnitz, B., & Gehring, U. (1997). The function of steroid hormone receptors is inhibited by the hsp90-specific compound geldanamycin. <em>Journal of Biological Chemistry</em>,<em> 272</em>(30), 18694-18701. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Stice, J. P., & Knowlton, A. A. (2008). Estrogen, NFκB, and the heat shock response. <em>Molecular Medicine</em>,<em> 14</em>, 517-527. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Van, d., Winter, R., Weimer, M., Beckmanns, P., Suzuki, G., Gijsberg, L., Jonas, A., Van, d. W., Hilda, & Aarts, J. Optimization and Prevalidation of the in Vitro ER CALUX Method to Test Estrogenic and Antiestrogenic Activity of Compounds. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Wehmas, L. C., Cavallin, J. E., Durhan, E. J., Kahl, M. D., Martinovic, D., Mayasich, J., Tuominen, T., Villeneuve, D. L., & Ankley, G. T. (2011). Screening complex effluents for estrogenic activity with the T47D‐KBluc cell bioassay: Assay optimization and comparison with in vivo responses in fish. <em>Environmental toxicology and chemistry</em>,<em> 30</em>(2), 439-445. </span></span></li>
</ul>
<p>Aranda, A., & Pascual, A. (2001). Nuclear hormone receptors and gene expression. Physiological reviews, 81(3), 1269-1304.</p>
<p>Ascenzi, P., Bocedi, A., & Marino, M. (2006). Structure–function relationship of estrogen receptor α and β: Impact on human health. Molecular aspects of medicine, 27(4), 299-402.</p>
<p>Asnake, S., Modig, C., & Olsson, P.-E. (2019). Species differences in ligand interaction and activation of estrogen receptors in fish and human. The Journal of steroid biochemistry and molecular biology, 195, 105450.</p>
<p>Balbi, T., Ciacci, C., & Canesi, L. (2019). Estrogenic compounds as exogenous modulators of physiological functions in molluscs: Signaling pathways and biological responses. Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 222, 135-144.</p>
<p>Berckmans, P., Leppens, H., Vangenechten, C., & Witters, H. (2007). Screening of endocrine disrupting chemicals with MELN cells, an ER-transactivation assay combined with cytotoxicity assessment. Toxicology in vitro, 21(7), 1262-1267.</p>
<p>Browne, P., Judson, R. S., Casey, W. M., Kleinstreuer, N. C., & Thomas, R. S. (2015). Screening Chemicals for Estrogen Receptor Bioactivity Using a Computational Model. Environmental Science & Technology, 49(14), 8804-8814. <a href="https://doi.org/10.1021/acs.est.5b02641">https://doi.org/10.1021/acs.est.5b02641</a></p>
<p>De Boever, P., Demaré, W., Vanderperren, E., Cooreman, K., Bossier, P., & Verstraete, W. (2001). Optimization of a yeast estrogen screen and its applicability to study the release of estrogenic isoflavones from a soygerm powder. Environmental Health Perspectives, 109(7), 691-697.</p>
<p>Fliss, A. E., Benzeno, S., Rao, J., & Caplan, A. J. (2000). Control of estrogen receptor ligand binding by Hsp90. The Journal of steroid biochemistry and molecular biology, 72(5), 223-230.</p>
<p>Keay, J., & Thornton, J. W. (2009). Hormone-activated estrogen receptors in annelid invertebrates: implications for evolution and endocrine disruption. Endocrinology, 150(4), 1731-1738.</p>
<p>Klinge, C. M. (2001). Estrogen receptor interaction with estrogen response elements. Nucleic Acids Res, 29(14), 2905-2919. <a href="https://doi.org/10.1093/nar/29.14.2905">https://doi.org/10.1093/nar/29.14.2905</a></p>
<p>Kumar, R., Zakharov, M. N., Khan, S. H., Miki, R., Jang, H., Toraldo, G., Singh, R., Bhasin, S., & Jasuja, R. (2011). The dynamic structure of the estrogen receptor. Journal of amino acids, 2011.</p>
<p>Menuet, A., Le Page, Y., Torres, O., Kern, L., Kah, O., & Pakdel, F. (2004). Analysis of the estrogen regulation of the zebrafish estrogen receptor (ER) reveals distinct effects of ERalpha, ERbeta1 and ERbeta2. Journal of Molecular Endocrinology, 32(3), 975-986.</p>
<p>Menuet, A., Pellegrini, E., Anglade, I., Blaise, O., Laudet, V., Kah, O., & Pakdel, F. (2002). Molecular characterization of three estrogen receptor forms in zebrafish: binding characteristics, transactivation properties, and tissue distributions. Biology of reproduction, 66(6), 1881-1892.</p>
<p>Ng, H. W., Perkins, R., Tong, W., & Hong, H. (2014). Versatility or Promiscuity: The Estrogen Receptors, Control of Ligand Selectivity and an Update on Subtype Selective Ligands. International Journal of Environmental Research and Public Health, 11(9), 8709-8742. <a href="https://www.mdpi.com/1660-4601/11/9/8709">https://www.mdpi.com/1660-4601/11/9/8709</a></p>
<p>Pillon, A., Boussioux, A.-M., Escande, A., Aït-Aïssa, S., Gomez, E., Fenet, H., Ruff, M., Moras, D., Vignon, F., & Duchesne, M.-J. (2005). Binding of estrogenic compounds to recombinant estrogen receptor-α: application to environmental analysis. Environmental Health Perspectives, 113(3), 278-284.</p>
<p>Schmieder, P. K., Kolanczyk, R. C., Hornung, M. W., Tapper, M. A., Denny, J. S., Sheedy, B. R., & Aladjov, H. (2014). A rule-based expert system for chemical prioritization using effects-based chemical categories. SAR and QSAR in Environmental Research, 25(4), 253-287. <a href="https://doi.org/10.1080/1062936X.2014.898691">https://doi.org/10.1080/1062936X.2014.898691</a></p>
<p>Segnitz, B., & Gehring, U. (1997). The function of steroid hormone receptors is inhibited by the hsp90-specific compound geldanamycin. Journal of Biological Chemistry, 272(30), 18694-18701.</p>
<p>Stice, J. P., & Knowlton, A. A. (2008). Estrogen, NFκB, and the heat shock response. Molecular Medicine, 14, 517-527.</p>
<p>Van, d., Winter, R., Weimer, M., Beckmanns, P., Suzuki, G., Gijsberg, L., Jonas, A., Van, d. W., Hilda, & Aarts, J. Optimization and Prevalidation of the in Vitro ER CALUX Method to Test Estrogenic and Antiestrogenic Activity of Compounds.</p>
<p>Wehmas, L. C., Cavallin, J. E., Durhan, E. J., Kahl, M. D., Martinovic, D., Mayasich, J., Tuominen, T., Villeneuve, D. L., & Ankley, G. T. (2011). Screening complex effluents for estrogenic activity with the T47D‐KBluc cell bioassay: Assay optimization and comparison with in vivo responses in fish. Environmental toxicology and chemistry, 30(2), 439-445.</p>
<h3>List of Key Events in the AOP</h3>
<h4><a href="/events/307">Event: 307: Increase, Vitellogenin synthesis in liver</a></h4>
<h5>Short Name: Increase, Vitellogenin synthesis in liver</h5>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Although vitellogenin is conserved among oviparous vertebrates and many invertebrates, liver is not a relevant tissue for the production of vitellogenin in invertebrates (Wahli, 1988).</span></span></span></li>
</ul>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Life stage: </strong>This KE is applicable to all life stages following the differentiation of the liver. Embryos prior to liver differentiation should not be included.</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Sex: </strong>This KE is applicable to both sexes.</span></span></span></p>
<h4>Key Event Description</h4>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><a name="_Hlk167176446"><span style="color:#333399">Vitellogenin (VTG) is an egg yolk precursor protein synthesized by hepatocytes of oviparous vertebrates </span></a><span style="color:#333399">(Hara et al., 2016). Transcription of <em>vtg</em> is regulated by estrogens and their interaction on ERs. </span></span></span><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">In males expression can be modulated by exogenous compounds. Under high estrogen stimulation the fold increase of <em>vtg</em> transcripts increases by orders of magnitude (Brock & Shapiro, 1983).</span></span></span></p>
<h4>How it is Measured or Detected</h4>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Relative abundance of vitellogenin transcripts or protein can be measured in liver tissue (e.g., Miracle et al., 2006), hepatocytes (e.g., Vaillant et al., 1988), exposed in vitro, or whole-body homogenates from organisms exposed in vivo (Holbech et al., 2001). </span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><span style="color:#333399">mRNA transcripts can be measured using real-time quantitative polymerase chain reaction (qPCR) while protein quantification can be measured using alkali-labile phosphoprotein (e.g., Kramer et al., 1998), or immunochemical methods such as radioimmunoassay (RIA; e.g., Tyler & Sumpter, 1990), enzyme linked immunosorbent </span><a name="_Hlk165465390"><span style="color:#333399">assay </span></a><span style="color:#333399">(ELISA; e.g., Denslow et al., 1999), and Western blotting (e.g., Heppell et al., 1995).</span></span></span></p>
<h4>References</h4>
<ul>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Brock, M. L., & Shapiro, D. (1983). Estrogen regulates the absolute rate of transcription of the Xenopus laevis vitellogenin genes. <em>Journal of Biological Chemistry</em>,<em> 258</em>(9), 5449-5455. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Denslow, N. D., Chow, M. C., Kroll, K. J., & Green, L. (1999). Vitellogenin as a biomarker of exposure for estrogen or estrogen mimics. <em>Ecotoxicology</em>,<em> 8</em>, 385-398. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Hara, A., Hiramatsu, N., & Fujita, T. (2016). Vitellogenesis and choriogenesis in fishes. <em>Fisheries Science</em>,<em> 82</em>(2), 187-202. <a href="https://doi.org/10.1007/s12562-015-0957-5" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1007/s12562-015-0957-5</a> </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Heppell, S. A., Denslow, N. D., Folmar, L. C., & Sullivan, C. V. (1995). Universal assay of vitellogenin as a biomarker for environmental estrogens. <em>Environmental Health Perspectives</em>,<em> 103</em>(suppl 7), 9-15. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Holbech, H., Andersen, L., Petersen, G. I., Korsgaard, B., Pedersen, K. L., & Bjerregaard, P. (2001). Development of an ELISA for vitellogenin in whole body homogenate of zebrafish (Danio rerio). <em>Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology</em>,<em> 130</em>(1), 119-131. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Kramer, V., Miles-Richardson, S., Pierens, S., & Giesy, J. (1998). Reproductive impairment and induction of alkaline-labile phosphate, a biomarker of estrogen exposure, in fathead minnows (Pimephales promelas) exposed to waterborne 17β-estradiol. <em>Aquatic Toxicology</em>,<em> 40</em>(4), 335-360. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Miracle, A., Ankley, G., & Lattier, D. (2006). Expression of two vitellogenin genes (vg1 and vg3) in fathead minnow (Pimephales promelas) liver in response to exposure to steroidal estrogens and androgens. <em>Ecotoxicology and environmental safety</em>,<em> 63</em>(3), 337-342. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Tyler, C. R., & Sumpter, J. P. (1990). The development of a radioimmunoassay for carp, Cyprinus carpio, vitellogenin. <em>Fish Physiology and Biochemistry</em>,<em> 8</em>, 129-140. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Vaillant, C., Le Guellec, C., Pakdel, F., & Valotaire, Y. (1988). Vitellogenin gene expression in primary culture of male rainbow trout hepatocytes. <em>General and Comparative Endocrinology</em>,<em> 70</em>(2), 284-290. </span></span></li>
<li><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Wahli, W. (1988). Evolution and expression of vitellogenin genes. <em>Trends in Genetics</em>,<em> 4</em>(8), 227-232. </span></span></li>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Taxonomic applicability:</strong> </span><span style="font-size:11pt">Oviparous vertebrates synthesize yolk precursor proteins that are transported in the circulation for uptake by developing oocytes. Many invertebrates also synthesize vitellogenins that are taken up into developing oocytes via active transport mechanisms. However, invertebrate vitellogenins are transported in hemolymph or via other transport mechanisms rather than plasma.</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Life stage: </strong>This KE is applicable to all life stages following the differentiation of the liver. Embryos prior to liver differentiation should not be included.</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Sex: </strong>This KE is applicable to both sexes.</span></span></span></p>
<h4>Key Event Description</h4>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Vitellogenins are large serum phospholipoglycoprotein that are encoded by a family of paralog genes whose number varies in the different vertebrate lineages resulting in numerous isoforms (Wahli, 1988). Vtg is synthesized in the liver and is secreted into the blood as ~500 kDa homodimers which circulate to the ovaries for uptake and bind to receptors on the surface of growing oocytes (Wallace, 1985).</span></span></span></p>
<h4>How it is Measured or Detected</h4>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Vitellogenin concentrations in plasma are typically measured using enzyme linked immunosorbent assay (ELISA; e.g., Denslow et al., 1999; Holbech et al., 2001). Less specific and/or sensitive assays such as determination of alkali-labile phosphoprotein (e.g., Kramer et al., 1998) and Western blotting (e.g., Heppell et al., 1995) may also be used.</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">There are also several standardized test guidelines that measure vtg including: Fish Short Term Reproduction Assay (OECD, 2009a), 21-day Fish Assay (OECD, 2009b); Fish Sexual Development Test (OECD, 2011), Medaka Extended One Generation Reproduction Test (OECD, 2015a). Measurement of vtg is also an optional parameter in the Larval Amphibian Growth and Development Assay (OECD, 2015b). The US Environmental Protection Agency (EPA) has similar standardized guidelines (US EPA, 2009, US EPA, 2014) as does the EU as part of the Guidance For The Identification Of Endocrine Disruptors In The Context Of Regulations (EC 2013, EC 2018).</span></span></span></p>
<h4>References</h4>
<ul>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Denslow, N. D., Chow, M. C., Kroll, K. J., & Green, L. (1999). Vitellogenin as a biomarker of exposure for estrogen or estrogen mimics. <em>Ecotoxicology</em>,<em> 8</em>, 385-398. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Heppell, S. A., Denslow, N. D., Folmar, L. C., & Sullivan, C. V. (1995). Universal assay of vitellogenin as a biomarker for environmental estrogens. <em>Environmental Health Perspectives</em>,<em> 103</em>(suppl 7), 9-15. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Holbech, H., Andersen, L., Petersen, G. I., Korsgaard, B., Pedersen, K. L., & Bjerregaard, P. (2001). Development of an ELISA for vitellogenin in whole body homogenate of zebrafish (Danio rerio). <em>Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology</em>,<em> 130</em>(1), 119-131. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Kramer, V., Miles-Richardson, S., Pierens, S., & Giesy, J. (1998). Reproductive impairment and induction of alkaline-labile phosphate, a biomarker of estrogen exposure, in fathead minnows (Pimephales promelas) exposed to waterborne 17β-estradiol. <em>Aquatic Toxicology</em>,<em> 40</em>(4), 335-360. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Wahli, W. (1988). Evolution and expression of vitellogenin genes. <em>Trends in Genetics</em>,<em> 4</em>(8), 227-232. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Wallace, R. A. (1985). Vitellogenesis and oocyte growth in nonmammalian vertebrates. <em>Oogenesis</em>, 127-177. </span></span></li>
</ul>
<h4><a href="/events/252">Event: 252: Increase, Renal pathology due to VTG deposition</a></h4>
<h5>Short Name: Increase, Renal pathology due to VTG deposition</h5>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Life stage: </strong>This KE is applicable to all life stages following the differentiation of the kidney.</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Sex: </strong>This KE is applicable to both sexes.</span></span></span></p>
<h4>Key Event Description</h4>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Renal pathology deals with the characterization of the kidneys. The kidneys perform a suite of physiological roles that are critical for organismal homeostasis including waste excretion, osmoregulation, and fluid homeostasis (Preuss, 1993). Each kidney is made up of specialized epithelial cells known as nephrons and while nephron numbers can vary greatly between species their overall function remains conserved in vertebrates (Desgrange & Cereghini, 2015). Nephrons act as filtering units that are composed of glomeruli and tubules which are responsible for removing metabolic waste from the bloodstream, regulating fluids, and balancing electrolytes (Wesselman et al., 2023). Organ tissue damage can occur after exposure to toxins, parasites, or be caused by disease. If pathology is measurable this would be an indication of damage or diseased tissue state and a departure from normal/healthy tissue.</span></span></span></p>
<h4>How it is Measured or Detected</h4>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Histopathology focuses on the changes in tissues and is a technique used for identifying correlations with biochemical markers. Generally renal pathology is measured after either whole organism or specific tissue of interest is fixed, dehydrated, and then embedded in wax, commonly paraffin wax. Sections are then cut to approximately 3–5 μm in thickness and stained before being examined under a microscope (e.g., Folmar et al., 2001; Mihaich et al., 2012; Zha et al., 2007).</span></span></span></p>
<ul>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">OECD Test No. 123: Guidance document on the diagnosis of endocrine-related histopathology in fish gonads (OECD 2010).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">OECD Test No. 227: Guidance document on medaka histopathology techniques and evaluation for the medaka extended one-generation reproduction test (OECD 2015)</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Crissman et al. (2004) describes best practice guidelines for toxicologic histopathology.</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Fiedler et al. (2023) have written standardized tissue sampling guidelines for histopathological analyses using rainbow trout.</span></span></span></li>
</ul>
<h4>References</h4>
<ul>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Crissman, J. W., Goodman, D. G., Hildebrandt, P. K., Maronpot, R. R., Prater, D. A., Riley, J. H., Seaman, W. J., & Thake, D. C. (2004). Best Practices Guideline: Toxicologic Histopathology. <em>Toxicologic Pathology</em>,<em> 32</em>(1), 126-131. <a href="https://doi.org/10.1080/01926230490268756" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1080/01926230490268756</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Desgrange, A., & Cereghini, S. (2015). Nephron patterning: lessons from Xenopus, zebrafish, and mouse studies. <em>Cells</em>,<em> 4</em>(3), 483-499. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Fiedler, S., Schrader, H., Theobalt, N., Hofmann, I., Geiger, T., Arndt, D., Wanke, R., Schwaiger, J., & Blutke, A. (2023). Standardized tissue sampling guidelines for histopathological and molecular analyses of rainbow trout (Oncorhynchus mykiss) in ecotoxicological studies. <em>PLOS ONE</em>,<em> 18</em>(7), e0288542. <a href="https://doi.org/10.1371/journal.pone.0288542" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1371/journal.pone.0288542</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Folmar, L. C., Gardner, G. R., Schreibman, M. P., Magliulo-Cepriano, L., Mills, L. J., Zaroogian, G., Gutjahr-Gobell, R., Haebler, R., Horowitz, D. B., & Denslow, N. D. (2001). Vitellogenin-induced pathology in male summer flounder (Paralichthys dentatus). <em>Aquatic Toxicology</em>,<em> 51</em>(4), 431-441. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Mihaich, E., Rhodes, J., Wolf, J., van der Hoeven, N., Dietrich, D., Hall, A. T., Caspers, N., Ortego, L., Staples, C., & Dimond, S. (2012). Adult fathead minnow, Pimephales promelas, partial life‐cycle reproductive and gonadal histopathology study with bisphenol A. <em>Environmental toxicology and chemistry</em>,<em> 31</em>(11), 2525-2535. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Preuss, H. G. (1993). Basics of renal anatomy and physiology. <em>Clinics in laboratory medicine</em>,<em> 13</em>(1), 1-11. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Wesselman, H. M., Gatz, A. E., Pfaff, M. R., Arceri, L., & Wingert, R. A. (2023). Estrogen signaling influences nephron segmentation of the zebrafish embryonic kidney. <em>Cells</em>,<em> 12</em>(4), 666. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Zha, J., Wang, Z., Wang, N., & Ingersoll, C. (2007). Histological alternation and vitellogenin induction in adult rare minnow (Gobiocypris rarus) after exposure to ethynylestradiol and nonylphenol. <em>Chemosphere</em>,<em> 66</em>(3), 488-495. </span></span></li>
<td><a href="/aops/16">Aop:16 - Acetylcholinesterase inhibition leading to acute mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/96">Aop:96 - Axonal sodium channel modulation leading to acute mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/104">Aop:104 - Altered ion channel activity leading impaired heart function</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/113">Aop:113 - Glutamate-gated chloride channel activation leading to acute mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/160">Aop:160 - Ionotropic gamma-aminobutyric acid receptor activation mediated neurotransmission inhibition leading to mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/161">Aop:161 - Glutamate-gated chloride channel activation leading to neurotransmission inhibition associated mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/138">Aop:138 - Organic anion transporter (OAT1) inhibition leading to renal failure and mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/177">Aop:177 - Cyclooxygenase 1 (COX1) inhibition leading to renal failure and mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/186">Aop:186 - unknown MIE leading to renal failure and mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/312">Aop:312 - Acetylcholinesterase Inhibition leading to Acute Mortality via Impaired Coordination & Movement</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/320">Aop:320 - Binding of SARS-CoV-2 to ACE2 receptor leading to acute respiratory distress associated mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/155">Aop:155 - Deiodinase 2 inhibition leading to increased mortality via reduced posterior swim bladder inflation</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/156">Aop:156 - Deiodinase 2 inhibition leading to increased mortality via reduced anterior swim bladder inflation</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/157">Aop:157 - Deiodinase 1 inhibition leading to increased mortality via reduced posterior swim bladder inflation </a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/158">Aop:158 - Deiodinase 1 inhibition leading to increased mortality via reduced anterior swim bladder inflation</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/159">Aop:159 - Thyroperoxidase inhibition leading to increased mortality via reduced anterior swim bladder inflation</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/363">Aop:363 - Thyroperoxidase inhibition leading to altered visual function via altered retinal layer structure</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/377">Aop:377 - Dysregulated prolonged Toll Like Receptor 9 (TLR9) activation leading to Multi Organ Failure involving Acute Respiratory Distress Syndrome (ARDS)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/364">Aop:364 - Thyroperoxidase inhibition leading to altered visual function via decreased eye size</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/365">Aop:365 - Thyroperoxidase inhibition leading to altered visual function via altered photoreceptor patterning</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/399">Aop:399 - Inhibition of Fyna leading to increased mortality via decreased eye size (Microphthalmos)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/413">Aop:413 - Oxidation and antagonism of reduced glutathione leading to mortality via acute renal failure</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/410">Aop:410 - GSK3beta inactivation leading to increased mortality via defects in developing inner ear</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/450">Aop:450 - Inhibition of AChE and activation of CYP2E1 leading to sensory axonal peripheral neuropathy and mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/536">Aop:536 - Estrogen receptor agonism leading to reduced survival and population growth due to renal failure</a></td>
<td>KeyEvent</td>
</tr>
<tr>
<td><a href="/aops/564">Aop:564 - DBDPE-induced inhibition of mitochondrial complex Ⅰ leading to population decline via neurotoxicity and metabotoxicity.</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/605">Aop:605 - Thyroid Peroxidase Inhibition Leading to Reduced, Swimming Performance via Hypomyelination</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/608">Aop:608 - Thyroid Hormone Excess Leading to Reduced, Swimming Performance via Hypomyelination</a></td>
<p>All living things are susceptible to mortality.</p>
<h4>Key Event Description</h4>
<p><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Increased mortality refers to an increase in the number of individuals dying in an experimental replicate group or in a population over a specific period of time.</span></span></span></span></p>
<h4>How it is Measured or Detected</h4>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="font-size:11pt"><span style="color:#212529"><span style="background-color:white">Mortality of animals is generally observed as cessation of the heart beat, breathing (gill or lung movement) and locomotory movements. Mortality is typically measured by observation. Depending on the size of the organism, instruments such as microscopes may be used. The reported metric is mostly the mortality rate: the number of deaths in a given area or period, or from a particular cause.</span></span></span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="font-size:11pt"><span style="color:#212529"><span style="background-color:white">Depending on the species and the study setup, mortality can be measured:</span></span></span></span></span></span></p>
<ul>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="font-size:11pt"><span style="color:#212529"><span style="background-color:white">in the lab by recording mortality during exposure experiments</span></span></span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="font-size:11pt"><span style="color:#212529"><span style="background-color:white">in dedicated setups simulating a realistic situation such as mesocosms or drainable ponds for aquatic species</span></span></span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="font-size:11pt"><span style="color:#212529"><span style="background-color:white">in the field, for example by determining age structure after one capture, or by capture-mark-recapture efforts. The latter is a method commonly used in ecology to estimate an animal population's size where it is impractical to count every individual.</span></span></span></span></span></li>
</ul>
<h4>Regulatory Significance of the AO</h4>
<p>Increased mortality is one of the most common regulatory assessment endpoints, along with reduced growth and reduced reproduction.</p>
<h4><a href="/events/360">Event: 360: Decrease, Population growth rate</a></h4>
<h5>Short Name: Decrease, Population growth rate</h5>
<td><a href="/aops/23">Aop:23 - Androgen receptor agonism leading to reproductive dysfunction (in repeat-spawning fish)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/25">Aop:25 - Aromatase inhibition leading to reproductive dysfunction</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/29">Aop:29 - Estrogen receptor agonism leading to reproductive dysfunction</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/30">Aop:30 - Estrogen receptor antagonism leading to reproductive dysfunction</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/100">Aop:100 - Cyclooxygenase inhibition leading to reproductive dysfunction via inhibition of female spawning behavior</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/122">Aop:122 - Prolyl hydroxylase inhibition leading to reproductive dysfunction via increased HIF1 heterodimer formation</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/123">Aop:123 - Unknown MIE leading to reproductive dysfunction via increased HIF-1alpha transcription</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/155">Aop:155 - Deiodinase 2 inhibition leading to increased mortality via reduced posterior swim bladder inflation</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/156">Aop:156 - Deiodinase 2 inhibition leading to increased mortality via reduced anterior swim bladder inflation</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/157">Aop:157 - Deiodinase 1 inhibition leading to increased mortality via reduced posterior swim bladder inflation </a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/158">Aop:158 - Deiodinase 1 inhibition leading to increased mortality via reduced anterior swim bladder inflation</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/159">Aop:159 - Thyroperoxidase inhibition leading to increased mortality via reduced anterior swim bladder inflation</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/101">Aop:101 - Cyclooxygenase inhibition leading to reproductive dysfunction via inhibition of pheromone release</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/102">Aop:102 - Cyclooxygenase inhibition leading to reproductive dysfunction via interference with meiotic prophase I /metaphase I transition</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/63">Aop:63 - Cyclooxygenase inhibition leading to reproductive dysfunction</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/103">Aop:103 - Cyclooxygenase inhibition leading to reproductive dysfunction via interference with spindle assembly checkpoint</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/292">Aop:292 - Inhibition of tyrosinase leads to decreased population in fish</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/310">Aop:310 - Embryonic Activation of the AHR leading to Reproductive failure, via epigenetic down-regulation of GnRHR</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/16">Aop:16 - Acetylcholinesterase inhibition leading to acute mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/312">Aop:312 - Acetylcholinesterase Inhibition leading to Acute Mortality via Impaired Coordination & Movement</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/334">Aop:334 - Glucocorticoid Receptor Agonism Leading to Impaired Fin Regeneration</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/336">Aop:336 - DNA methyltransferase inhibition leading to population decline (1)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/337">Aop:337 - DNA methyltransferase inhibition leading to population decline (2)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/338">Aop:338 - DNA methyltransferase inhibition leading to population decline (3)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/339">Aop:339 - DNA methyltransferase inhibition leading to population decline (4)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/340">Aop:340 - DNA methyltransferase inhibition leading to transgenerational effects (1)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/341">Aop:341 - DNA methyltransferase inhibition leading to transgenerational effects (2)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/289">Aop:289 - Inhibition of 5α-reductase leading to impaired fecundity in female fish</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/297">Aop:297 - Inhibition of retinaldehyde dehydrogenase leads to population decline</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/346">Aop:346 - Aromatase inhibition leads to male-biased sex ratio via impacts on gonad differentiation</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/326">Aop:326 - Thermal stress leading to population decline (3)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/325">Aop:325 - Thermal stress leading to population decline (2)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/324">Aop:324 - Thermal stress leading to population decline (1)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/363">Aop:363 - Thyroperoxidase inhibition leading to altered visual function via altered retinal layer structure</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/349">Aop:349 - Inhibition of 11β-hydroxylase leading to decresed population trajectory </a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/348">Aop:348 - Inhibition of 11β-Hydroxysteroid Dehydrogenase leading to decreased population trajectory </a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/376">Aop:376 - Androgen receptor agonism leading to male-biased sex ratio</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/386">Aop:386 - Deposition of ionizing energy leading to population decline via inhibition of photosynthesis</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/387">Aop:387 - Deposition of ionising energy leading to population decline via mitochondrial dysfunction</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/388">Aop:388 - Deposition of ionising energy leading to population decline via programmed cell death</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/389">Aop:389 - Oxygen-evolving complex damage leading to population decline via inhibition of photosynthesis</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/364">Aop:364 - Thyroperoxidase inhibition leading to altered visual function via decreased eye size</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/365">Aop:365 - Thyroperoxidase inhibition leading to altered visual function via altered photoreceptor patterning</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/399">Aop:399 - Inhibition of Fyna leading to increased mortality via decreased eye size (Microphthalmos)</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/410">Aop:410 - GSK3beta inactivation leading to increased mortality via defects in developing inner ear</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/216">Aop:216 - Deposition of energy leading to population decline via DNA strand breaks and follicular atresia</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/238">Aop:238 - Deposition of energy leading to population decline via DNA strand breaks and oocyte apoptosis</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/299">Aop:299 - Deposition of energy leading to population decline via DNA oxidation and follicular atresia</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/311">Aop:311 - Deposition of energy leading to population decline via DNA oxidation and oocyte apoptosis</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/444">Aop:444 - Ionizing radiation leads to reduced reproduction in Eisenia fetida via reduced spermatogenesis and cocoon hatchability</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/138">Aop:138 - Organic anion transporter (OAT1) inhibition leading to renal failure and mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/177">Aop:177 - Cyclooxygenase 1 (COX1) inhibition leading to renal failure and mortality</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/97">Aop:97 - 5-hydroxytryptamine transporter (5-HTT; SERT) inhibition leading to population decline</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/203">Aop:203 - 5-hydroxytryptamine transporter inhibition leading to decreased reproductive success and population decline</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/218">Aop:218 - Inhibition of CYP7B activity leads to decreased reproductive success via decreased locomotor activity</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/219">Aop:219 - Inhibition of CYP7B activity leads to decreased reproductive success via decreased sexual behavior</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/323">Aop:323 - PPARalpha Agonism Leading to Decreased Viable Offspring via Decreased 11-Ketotestosterone</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/536">Aop:536 - Estrogen receptor agonism leading to reduced survival and population growth due to renal failure</a></td>
<td>KeyEvent</td>
</tr>
<tr>
<td><a href="/aops/540">Aop:540 - Oxidative Stress in the Fish Ovary Leads to Reproductive Impairment via Reduced Vitellogenin Production</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/564">Aop:564 - DBDPE-induced inhibition of mitochondrial complex Ⅰ leading to population decline via neurotoxicity and metabotoxicity.</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/567">Aop:567 - Binding to plastoquinone B site leading to decreased population growth rate via photosystem II inhibition</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/592">Aop:592 - DBDPE-induced DNA strand breaks and LDH activity inhibition leading to population growth rate decline via energy metabolism disrupt and apoptosis</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/605">Aop:605 - Thyroid Peroxidase Inhibition Leading to Reduced, Swimming Performance via Hypomyelination</a></td>
<td>AdverseOutcome</td>
</tr>
<tr>
<td><a href="/aops/608">Aop:608 - Thyroid Hormone Excess Leading to Reduced, Swimming Performance via Hypomyelination</a></td>
<p>Consideration of population size and changes in population size over time is potentially relevant to all living organisms.</p>
<h4>Key Event Description</h4>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">A population can be defined as a group of interbreeding organisms, all of the same species, occupying a specific space during a specific time (Vandermeer and Goldberg 2003, Gotelli 2008). As the population is the biological level of organization that is often the focus of ecological risk</span> <span style="color:black">assessments, population growth rate (and hence population size over time) is important to consider within the context of applied conservation practices.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">If N is the size of the population and t is time, then the population growth rate (dN/dt) is proportional to the instantaneous rate of increase, r, which measures the per capita rate of population increase over a short time interval. Therefore, r, is a difference between the instantaneous birth rate (number of births per individual per unit of time; b) and the instantaneous death rate (number of deaths per individual per unit of time; d) [Equation 1]. Because r is an instantaneous rate, its units can be changed via division. For example, as there are 24 hours in a day, an r of 24 individuals/(individual x day) is equal to an r of 1 individual/(individual/hour) (Caswell 2001, Vandermeer and Goldberg 2003, Gotelli 2008, Murray and Sandercock 2020). </span></span></span></span></p>
<p style="margin-left:144px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Equation 1: r = b - d</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">This key event refers to scenarios where r < 0 (instantaneous death rate exceeds instantaneous birth rate).</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Examining r in the context of population growth rate:</span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● A population will decrease to extinction when the instantaneous death rate exceeds the instantaneous birth rate (r < 0). </span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black"> ● The smaller the value of r below 1, the faster the population will decrease to zero. </span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● A population will increase when resources are available and the instantaneous birth rate exceeds the instantaneous death rate (r > 0)</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black"> ● The larger the value that r exceeds 1, the faster the population can increase over time </span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● A population will neither increase or decrease when the population growth rate equals 0 (either due to N = 0, or if the per capita birth and death rates are exactly balanced). For example, the per capita birth and death rates could become exactly balanced due to density dependence and/or to the effect of a stressor that reduces survival and/or reproduction (Caswell 2001, Vandermeer and Goldberg 2003, Gotelli 2008, Murray and Sandercock 2020). </span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Effects incurred on a population from a chemical or non-chemical stressor could have an impact directly upon birth rate (reproduction) and/or death rate (survival), thereby causing a decline in population growth rate. </span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● Example of direct effect on r: Exposure to 17b-trenbolone reduced reproduction (i.e., reduced b) in the fathead minnow over 21 days at water concentrations ranging from 0.0015 to about 41 mg/L (Ankley et al. 2001; Miller and Ankley 2004). </span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Alternatively, a stressor could indirectly impact survival and/or reproduction. </span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● Example of indirect effect on r: Exposure of non-sexually differentiated early life stage fathead minnow to the fungicide prochloraz has been shown to produce male-biased sex ratios based on gonad differentiation, and resulted in projected change in population growth rate (decrease in reproduction due to a decrease in females and thus recruitment) using a population model. (Holbech et al., 2012; Miller et al. 2022)</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Density dependence can be an important consideration:</span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● The effect of density dependence depends upon the quantity of resources present within a landscape. A change in available resources could increase or decrease the effect of density dependence and therefore cause a change in population growth rate via indirectly impacting survival and/or reproduction. </span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● This concept could be thought of in terms of community level interactions whereby one species is not impacted but a competitor species is impacted by a chemical stressor resulting in a greater availability of resources for the unimpacted species. In this scenario, the impacted species would experience a decline in population growth rate. The unimpacted species would experience an increase in population growth rate (due to a smaller density dependent effect upon population growth rate for that species). </span> </span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Closed versus open systems:</span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● The above discussion relates to closed systems (there is no movement of individuals between population sites) and thus a declining population growth rate cannot be augmented by immigration. </span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● When individuals depart (emigrate out of a population) the loss will diminish population growth rate. </span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Population growth rate applies to all organisms, both sexes, and all life stages.</span></span></span></span></p>
<p> </p>
<h4>How it is Measured or Detected</h4>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Population growth rate (instantaneous growth rate) can be measured by sampling a population over an interval of time (i.e. from time t = 0 to time t = 1). The interval of time should be selected to correspond to the life history of the species of interest (i.e. will be different for rapidly growing versus slow growing populations). The population growth rate, r, can be determined by taking the difference (subtracting) between the initial population size, N</span><sub><span style="font-size:9pt"><span style="color:black">t=0 </span></span></sub><span style="color:black">(population size at time t=0), and the population size at the end of the interval, N</span><sub><span style="font-size:9pt"><span style="color:black">t=1 </span></span></sub><span style="color:black">(population size at time t = 1), and then subsequently dividing by the initial population size. </span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">The diversity of forms, sizes, and life histories among species has led to the development of a vast number of field techniques for estimation of population size and thus population growth over time (Bookhout 1994, McComb et al. 2021). </span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● For stationary species an observational strategy may involve dividing a habitat into units. After setting up the units, samples are performed throughout the habitat at a select number of units (determined using a statistical sampling design) over a time interval (at time t = 0 and again at time t = 1), and the total number of organisms within each unit are counted. The numbers recorded are assumed to be representative for the habitat overall, and can be used to estimate the population growth rate within the entire habitat over the time interval. </span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● For species that are mobile throughout a large range, a strategy such as using a mark-recapture method may be employed (i.e. tags, bands, transmitters) to determine a count over a time interval (at time = 0 and again at time =1). </span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Population growth rate can also be estimated using mathematical model constructs (for example, ranging from simple differential equations to complex age or stage structured matrix projection models and individual based modeling approaches), and may assume a linear or nonlinear population increase over time (Caswell 2001, Vandermeer and Goldberg 2003, Gotelli 2008, Murray and Sandercock 2020). The AOP framework can be used to support the translation of pathway-specific mechanistic data into responses relevant to population models and output from the population models, such as changing (declining) population growth rate, can be used to assess and manage risks of chemicals (Kramer et al. 2011). As such, this translational capability can increase the capacity and efficiency of safety assessments both for single chemicals and chemical mixtures (Kramer et al. 2011). </span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Some examples of modeling constructs used to investigate population growth rate:</span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● A modeling construct could be based upon laboratory toxicity tests to determine effect(s) that are then linked to the population model and used to estimate decline in population growth rate. Miller et al. (2007) used concentration–response data from short term reproductive assays with fathead minnow (<em>Pimephales promelas</em>) exposed to endocrine disrupting chemicals in combination with a population model to examine projected alterations in population growth rate. </span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● A model construct could be based upon a combination of effects-based monitoring at field sites (informed by an AOP) and a population model. Miller et al. (2015) applied a population model informed by an AOP to project declines in population growth rate for white suckers (Catostomus commersoni) using observed changes in sex steroid synthesis in fish exposed to a complex pulp and paper mill effluent in Jackfish Bay, Ontario, Canada. Furthermore, a model construct could be comprised of a series of quantitative models using KERs that culminates in the estimation of change (decline) in population growth rate. </span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● A quantitative adverse outcome pathway (qAOP) has been defined as a mathematical construct that models the dose–response or response–response relationships of all KERs described in an AOP (Conolly et al. 2017, Perkins et al. 2019). Conolly et al. (2017) developed a qAOP using data generated with the aromatase inhibitor fadrozole as a stressor and then used it to predict potential population‐level impacts (including decline in population growth rate). The qAOP modeled aromatase inhibition (the molecular initiating event) leading to reproductive dysfunction in fathead minnow (Pimephales promelas) using 3 computational models: a hypothalamus–pituitary–gonadal axis model (based on ordinary differential equations) of aromatase inhibition leading to decreased vitellogenin production (Cheng et al. 2016), a stochastic model of oocyte growth dynamics relating vitellogenin levels to clutch size and spawning intervals (Watanabe et al. 2016), and a population model (Miller et al. 2007).</span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● Dynamic energy budget (DEB) models offer a methodology that reverse engineers stressor effects on growth, reproduction, and/or survival into modular characterizations related to the acquisition and processing of energy resources (Nisbet et al. 2000, Nisbet et al. 2011). Murphy et al. (2018) developed a conceptual model to link DEB and AOP models by interpreting AOP key events as measures of damage-inducing processes affecting DEB variables and rates.</span></span></span></span></p>
<p style="margin-left:48px; text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">● Endogenous Lifecycle Models (ELMs), capture the endogenous lifecycle processes of growth, development, survival, and reproduction and integrate these to estimate and predict expected fitness (Etterson and Ankley, 2021). AOPs can be used to inform ELMs of effects of chemical stressors on the vital rates that determine fitness, and to decide what hierarchical models of endogenous systems should be included within an ELM (Etterson and Ankley, 2021).</span></span></span></span></p>
<p> </p>
<h4>Regulatory Significance of the AO</h4>
<p>Maintenance of sustainable fish and wildlife populations (i.e., adequate to ensure long-term delivery of valued ecosystem services) is a widely accepted regulatory goal upon which risk assessments and risk management decisions are based.</p>
<h4>References</h4>
<ul>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Ankley GT, Jensen KM, Makynen EA, Kahl MD, Korte JJ, Hornung MW, Henry TR, Denny JS, Leino RL, Wilson VS, Cardon MD, Hartig PC, Gray LE. 2003. Effects of the androgenic growth promoter 17b-trenbolone on fecundity and reproductive endocrinology of the fathead minnow. Environ. Toxicol. Chem. 22: 1350–1360.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Bookhout TA. 1994. Research and management techniques for wildlife and habitats. The Wildlife Society, Bethesda, Maryland. 740 pp.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Cheng WY, Zhang Q, Schroeder A, Villeneuve DL, Ankley GT, Conolly R. 2016. Computational modeling of plasma vitellogenin alterations in response to aromatase inhibition in fathead minnows. Toxicol Sci 154: 78–89.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Conolly RB, Ankley GT, Cheng W-Y, Mayo ML, Miller DH, Perkins EJ, Villeneuve DL, Watanabe KH. 2017. Quantitative adverse outcome pathways and their application to predictive toxicology. Environ. Sci. Technol. 51: 4661-4672.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Etterson MA, Ankley GT. 2021. Endogenous Lifecycle Models for Chemical Risk Assessment. Environ. Sci. Technol. 55: 15596-15608. </span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Gotelli NJ, 2008. A Primer of Ecology. Sinauer Associates, Inc., Sunderland, MA, USA.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Holbech H, Kinnberg KL, Brande-Lavridsen N, Bjerregaard P, Petersen GI, Norrgren L, Orn S, Braunbeck T, Baumann L, Bomke C, Dorgerloh M, Bruns E, Ruehl-Fehlert C, Green JW, Springer TA, Gourmelon A. 2012 Comparison of zebrafish (<em>Danio rerio</em>) and fathead minnow <em>(Pimephales promelas</em>) as test species in the Fish Sexual Development Test (FSDT). Comp. Biochem. Physiol. C Toxicol. Pharmacol. 155: 407–415.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Kramer VJ, Etterson MA, Hecker M, Murphy CA, Roesijadi G, Spade DJ, Stromberg JA, Wang M, Ankley GT. </span><span style="color:black">2011. Adverse outcome pathways and risk assessment: Bridging to population level effects. Environ. Toxicol. Chem. 30, 64-76.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">McComb B, Zuckerberg B, Vesely D, Jordan C. 2021. Monitoring Animal Populations and their Habitats: A Practitioner's Guide. Pressbooks, Oregon State University, Corvallis, OR Version 1.13, 296 pp. </span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Miller DH, Villeneuve DL, Santana Rodriguez KJ, Ankley GT. 2022. A multidimensional matrix model for predicting the effect of male biased sex ratios on fish populations. Environmental Toxicology and Chemistry 41(4): 1066-1077.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Miller DH, Tietge JE, McMaster ME, Munkittrick KR, Xia X, Griesmer DA, Ankley GT. 2015. </span><span style="color:black">Linking mechanistic toxicology to population models in forecasting recovery from chemical stress: A case study from Jackfish Bay, Ontario, Canada. Environmental Toxicology and Chemistry 34(7): 1623-1633.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Miller DH, Jensen KM, Villeneuve DE, Kahl MD, Makynen EA, Durhan EJ, Ankley GT. 2007. </span><span style="color:black">Linkage of biochemical responses to population-level effects: A case study with vitellogenin in the fathead minnow (<em>Pimephales promelas</em>). Environ Toxicol Chem 26: 521–527.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Miller DH, Ankley GT. 2004. Modeling impacts on populations: Fathead minnow (<em>Pimephales promelas</em>) exposure to the endocrine disruptor 17b-trenbolone as a case study. Ecotox Environ Saf 59: 1–9.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Murphy CA, Nisbet RM, Antczak P, Garcia-Reyero N, Gergs A, Lika K, Mathews T, Muller EB, Nacci D, Peace A, Remien CH, Schultz IR, Stevenson LM, Watanabe KH. 2018. Incorporating suborganismal processes into dynamic energy budget models for ecological risk assessment. Integrated Environmental Assessment and Management 14(5): 615–624.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Murray DL, Sandercock BK (editors). 2020. Population ecology in practice. Wiley-Blackwell, Oxford UK, 448 pp.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Nisbet RM, Jusup M, Klanjscek T, Pecquerie L. 2011. Integrating dynamic energy budget (DEB) theory with traditional bioenergetic models. The Journal of Experimental Biology 215: 892-902.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Nisbet RM, Muller EB, Lika K, Kooijman SALM. 2000. </span><span style="color:black">From molecules to ecosystems through dynamic energy budgets. J Anim Ecol 69: 913–926.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Perkins EJ, Ashauer R, Burgoon L, Conolly R, Landesmann B,, Mackay C, Murphy CA, Pollesch N, Wheeler JR, Zupanic A, Scholzk S. 2019. Building and applying quantitative adverse outcome pathway models for chemical hazard and risk assessment. Environmental Toxicology and Chemistry 38(9): 1850–1865. </span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Vandermeer JH, Goldberg DE. 2003. Population ecology: first principles. Princeton University Press, Princeton NJ, 304 pp.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Villeneuve DL, Crump D, Garcia-Reyero N, Hecker M, Hutchinson TH, LaLone CA, Landesmann B, Lattieri T, Munn S, Nepelska M, Ottinger MA, Vergauwen L, Whelan M. Adverse outcome pathway (AOP) development 1: Strategies and principles. Toxicol Sci. 2014: 142:312–320</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">Watanabe KH, Mayo M, Jensen KM, Villeneuve DL, Ankley GT, Perkins EJ. 2016. Predicting fecundity of fathead minnows (<em>Pimephales promelas</em>) exposed to endocrine‐disrupting chemicals using a MATLAB(R)‐based model of oocyte growth dynamics. PLoS One 11: e0146594.</span></span></span></li>
</ul>
<h2>Appendix 2</h2>
<h2>List of Key Event Relationships in the AOP</h2>
<div id="evidence_supporting_links">
<h3>List of Adjacent Key Event Relationships</h3>
<div>
<h4><a href="/relationships/128">Relationship: 128: Agonism, Estrogen receptor leads to Increase, Vitellogenin synthesis in liver</a></h4>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Life stage</strong>: This KER is applicable to all life stages following the differentiation of the liver. Larvae prior to liver differentiation should not be included.</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Sex</strong>: This KER is applicable to both sexes.</span></span></span></p>
<h4>Evidence Supporting this KER</h4>
<strong>Biological Plausibility</strong>
<p>Original text - unknown contributor</p>
<p><em>High degree of plausibility in fathead minnow, zebrafish and other cyprinid species. </em></p>
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<p><span style="color:#333399">Added by C. Baettig June 24, 2024</span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">In egg laying vertebrates such as fish vitellogenin (VTG) synthesis occurs in the female liver after activation of estrogen receptors (ERs), including ERα and ERβ isoforms, by endogenous steroids and a variety of exogenous chemicals that bind to ERs (e.g., Brock & Shapiro, 1983; Denslow et al., 1999; Miracle et al., 2006). In mature female fish VTG is incorporated into growing oocytes by the ovary and is converted into yolk protein. However, neither adult male fish nor juvenile fish normally produce VTG, but the hepatic ER is present in males, as are the genes that encode for <em>vtg</em> expression and can therefore be induced by exogenous compounds (Heppell et al., 1995). </span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Agonism of the ER is expected to increase <em>vtg</em> transcription and translation and under high estrogen stimulation the fold increase of <em>vtg</em> transcripts increases by orders of magnitude (Brock & Shapiro, 1983). As such, induction of VTG levels in male fish has been used extensively as a biomarker of estrogen exposure (Wheeler et al., 2005).</span></span></span></p>
<strong>Empirical Evidence</strong>
<p>Original text - unknown contributor</p>
<p><em>A wide range of studies using adult fish show that induction of plasma vitellogenin (VTG) occurs within 21 days in vivo aquatic exposure to estrogen receptor agonists (eg 17beta-estradiol and 4-tert pentylphenol) as shown during the successful validation of the OECD Test Guideline 229 and related protocols. A smaller number of experiment studies with fish have shown that within the OECD Test Guideline 2010, larval fish can also show induction of whole body VTG levels within 21 days aquatic exposure to estrogen receptor agonists. </em></p>
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<p><span style="color:#333399">Added by C. Baettig June 24, 2024</span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">There are numerous publications supporting this relationship including multiple review articles (e.g., Matozzo et al., 2008; Palmer & Selcer, 1996; Verderame & Scudiero, 2017). A few specific examples are listed below.</span></span></span></p>
<ul>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Estradiol and diarylpropionitrile (DPN), an ERβ selective agonist, induced a dose-dependent increase in VTG synthesis in rainbow trout hepatocytes (Leaños-Castañeda & Van Der Kraak, 2007).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">DPN has also been shown to increase ERα and <em>vtg</em> expression and synthesis post-injection in Mozambique tilapia in vivo (Davis et al., 2010). </span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">A study focusing on benzophenone derivatives found that BP1 (2,4-dihydroxybenzophenone), BP2 (2,2′,4,4′-tetrahydroxybenzophenone), and THB (2,4,4′-trihydroxybenzophenone) were human ERα (hERα) and hERβ and rainbow trout ERα (rtERα) and rtERβ agonists. To investigate ER activation profiles of the derivatives in vitro tests, i.e., competitive binding, reporter gene based assays, vitellogenin (Vtg) induction in isolated rainbow trout hepatocytes, and proliferation based assays were completed. hERβ was more strongly activated, which is an inverse finding to natural ligand 17β-estradiol (E2) where hERα is more strongly activated. BPs were more active in rtERα than in hERα assays. Significant VTG induction was detected in hERα, hERβ, rtERα, and rtERβ cultures (Molina-Molina et al., 2008).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Tollefsen et al. (2003) looked at multiple endogenous (e.g., estrone (E1), estradiol (E2), and estriol (E3)) and exogenous estrogens (e.g., ethynyloestradiol (EE2), diethylstilbestrol (DES), genistein, zearalenone, bisphenol A) and found they induced dose-dependent VTG synthesis in Atlantic salmon hepatocytes.</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Shen et al. (2021) used in silico methods to screen 1056 pesticides for potential agonistic activity. They found 72 pesticides to be potential ER agonists, 14 of which have been previously reported as ER agonists. To test whether these pesticides were ER agonists, 10 were selected from the list, three that were previously reported as ER agonists and seven previously unreported as ER agonists. They found all 10 pesticides exhibited ERα agonistic activity in human or zebrafish cells and of the 10, seven also induced <em>vtg1</em> and <em>vtg2</em> mRNA in zebrafish. </span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Xu et al (2020) also showed increase in plasma VTG following exposure to aryloxy-phenoxypropionate (APP) herbicides, after measuring the binding patterns of quizalofop-P-ethyl (QPE), clodinafop-propargyl (CP) and haloxyfop-P (HP) with ERα. </span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">In male fathead minnows exposed to E2 and <span style="font-size:12.0pt">1H,1H,10H,10H-perfluorodecane-1,10-diol</span> (FC-10 diol) for 21 days expression of hepatic <em>esr1</em> and <em>vtg</em> were both significantly increased (Ankley et al. in prep).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">In male fathead minnows exposed to methoxychlor, a weak estrogen agonist, there was a clear induction of VTG (Ankley et al. 2001). In the same study exposure to methyltestosterone, a synthetic androgen, caused a significant induction of VTG in both male and female fathead minnows. This level of induction in female fathead minnows resulted in a dose-dependent increase in VTG, to concentrations approximately 10-fold higher than those observed in control fish. These funding were likely due to the conversion of methyltestosterone to methylestradiol (Hornung et al., 2004).</span></span></span></li>
</ul>
<strong>Uncertainties and Inconsistencies</strong>
<p>Original text - unknown contributor</p>
<p><em>There are generally few inconsistencies for experimental studies using model fish species dervied from pathogen-free laboratory cultures. However, there can some uncertainties where wild fish have been used for experimental purposes. </em></p>
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<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif">Added by C. Baettig June 24, 2024</span></span></p>
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<ul>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Some uncertainty remains regarding which ER subtypes regulate <em>vtg</em> gene expression in the liver of fish. In general, the literature suggests a close interplay between ER subtypes, primarily ERα and Erβ, in the regulation of vitellogenesis. Consequently, at present, the key event relationship is generalized to impacts on all ER subtypes, even though it remains possible that impacts on a particular sub-type may drive the effect on vitellogenin transcription and translation.</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Using selective agonists and antagonists for ERα and ERβ, it was concluded that ERβ was primarily responsible for inducing vitellogenin production in rainbow trout and that compounds exhibiting ERα selectivity would not be detected using a vitellogenin ELISA bioassay (Leaños-Castañeda & Van Der Kraak, 2007). However, a subsequent study conducted in tilapia concluded that agonistic and antagonistic characteristics of mammalian, isoform-specific ER agonists and antagonists, cannot be reliably extrapolated to piscine ERs (Davis et al., 2010).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Based on RNA interference knock-down experiments Nelson and Habibi (2010) proposed a model in which all ER subtypes are involved in E2-mediated vitellogenesis, with ERβ isoforms stimulating expression of both vitellogenin and ERα gene expression, and ERα helping to drive vitellogenesis, particularly as it becomes more abundant following sensitization.</span></span></span></li>
</ul>
<h4>References</h4>
<p>Navas, J.M., Segner, H. (2006) Vitellogenin synthesis in primary cultures of fish liver cells as endpoint for in vitro screening of the (anti)estrogenic activity of chemical substances. Aquatic Toxicology 80: 1-22</p>
<p>Thorpe, K.L., Benstead, R., Hutchinson, T.H., Tyler, C.R. (2007). Associations between altered vitellogenin concentrations and adverse health effects in fathead minnow (Pimephales promelas). Aquatic Toxicology 85: 176-183</p>
<p> </p>
<ul>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Brock, M. L., & Shapiro, D. (1983). Estrogen regulates the absolute rate of transcription of the Xenopus laevis vitellogenin genes. <em>Journal of Biological Chemistry</em>,<em> 258</em>(9), 5449-5455. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Davis, L., Katsu, Y., Iguchi, T., Lerner, D., Hirano, T., & Grau, E. (2010). Transcriptional activity and biological effects of mammalian estrogen receptor ligands on three hepatic estrogen receptors in Mozambique tilapia. <em>The Journal of steroid biochemistry and molecular biology</em>,<em> 122</em>(4), 272-278. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Denslow, N. D., Chow, M. C., Kroll, K. J., & Green, L. (1999). Vitellogenin as a biomarker of exposure for estrogen or estrogen mimics. <em>Ecotoxicology</em>,<em> 8</em>, 385-398. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Hornung, M. W., Jensen, K. M., Korte, J. J., Kahl, M. D., Durhan, E. J., Denny, J. S., Henry, T. R., & Ankley, G. T. (2004). Mechanistic basis for estrogenic effects in fathead minnow (Pimephales promelas) following exposure to the androgen 17α-methyltestosterone: conversion of 17α-methyltestosterone to 17α-methylestradiol. <em>Aquatic Toxicology</em>,<em> 66</em>(1), 15-23. <a href="https://doi.org/https:/doi.org/10.1016/j.aquatox.2003.06.004" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.aquatox.2003.06.004</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Leaños-Castañeda, O., & Van Der Kraak, G. (2007). Functional characterization of estrogen receptor subtypes, ERα and ERβ, mediating vitellogenin production in the liver of rainbow trout. <em>Toxicology and applied pharmacology</em>,<em> 224</em>(2), 116-125. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Matozzo, V., Gagné, F., Marin, M. G., Ricciardi, F., & Blaise, C. (2008). Vitellogenin as a biomarker of exposure to estrogenic compounds in aquatic invertebrates: A review. <em>Environment International</em>,<em> 34</em>(4), 531-545. <a href="https://doi.org/https:/doi.org/10.1016/j.envint.2007.09.008" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.envint.2007.09.008</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Miracle, A., Ankley, G., & Lattier, D. (2006). Expression of two vitellogenin genes (vg1 and vg3) in fathead minnow (Pimephales promelas) liver in response to exposure to steroidal estrogens and androgens. <em>Ecotoxicology and environmental safety</em>,<em> 63</em>(3), 337-342. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Molina-Molina, J.-M., Escande, A., Pillon, A., Gomez, E., Pakdel, F., Cavaillès, V., Olea, N., Aït-Aïssa, S., & Balaguer, P. (2008). Profiling of benzophenone derivatives using fish and human estrogen receptor-specific in vitro bioassays. <em>Toxicology and applied pharmacology</em>,<em> 232</em>(3), 384-395. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Nelson, E. R., & Habibi, H. R. (2010). Functional Significance of Nuclear Estrogen Receptor Subtypes in the Liver of Goldfish. <em>Endocrinology</em>,<em> 151</em>(4), 1668-1676. <a href="https://doi.org/10.1210/en.2009-1447" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1210/en.2009-1447</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Palmer, B. D., & Selcer, K. W. (1996). Vitellogenin as a biomarker for xenobiotic estrogens: a review. <em>Environmental Toxicology and Risk Assessment: Biomarkers and Risk Assessment: Fifth Volume</em>, 3-22. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Shen, C., Zhu, K., Ruan, J., Li, J., Wang, Y., Zhao, M., He, C., & Zuo, Z. (2021). Screening of potential oestrogen receptor α agonists in pesticides via in silico, in vitro and in vivo methods. <em>Environmental Pollution</em>,<em> 270</em>, 116015. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Tollefsen, K.-E., Mathisen, R., & Stenersen, J. (2003). Induction of vitellogenin synthesis in an Atlantic salmon (Salmo salar) hepatocyte culture: a sensitive in vitro bioassay for the oestrogenic and anti-oestrogenic activity of chemicals. <em>Biomarkers</em>,<em> 8</em>(5), 394-407. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Verderame, M., & Scudiero, R. (2017). Estrogen-dependent, extrahepatic synthesis of vitellogenin in male vertebrates: A mini-review. <em>Comptes Rendus Biologies</em>,<em> 340</em>(3), 139-144. <a href="https://doi.org/https:/doi.org/10.1016/j.crvi.2017.01.005" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.crvi.2017.01.005</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Wheeler, J. R., Gimeno, S., Crane, M., Lopez-Juez, E., & Morritt, D. (2005). Vitellogenin: a review of analytical methods to detect (anti) estrogenic activity in fish. <em>Toxicology Mechanisms and Methods</em>,<em> 15</em>(4), 293-306. </span></span></li>
<li><span style="font-size:11.0pt"><span style="font-family:"Calibri",sans-serif">Xu, Y., Feng, R., Wang, L., Dong, L., Liu, R., Lu, H., & Wang, C. (2020). Computational and experimental investigations on the interactions of aryloxy-phenoxy-propionate herbicides to estrogen receptor alpha in zebrafish. <em>Ecotoxicology and environmental safety</em>,<em> 189</em>, 110003. </span></span></li>
</ul>
</div>
<div>
<h4><a href="/relationships/336">Relationship: 336: Increase, Vitellogenin synthesis in liver leads to Increase, Plasma vitellogenin concentrations</a></h4>
<td><a href="/aops/29">Estrogen receptor agonism leading to reproductive dysfunction</a></td>
<td>adjacent</td>
<td>High</td>
<td></td>
</tr>
<tr>
<td><a href="/aops/536">Estrogen receptor agonism leading to reduced survival and population growth due to renal failure</a></td>
<td>adjacent</td>
<td>High</td>
<td>Moderate</td>
</tr>
<tr>
<td><a href="/aops/537">Estrogen receptor agonism leads to reduced fecundity via increased vitellogenin in the liver</a></td>
<td>adjacent</td>
<td></td>
<td></td>
</tr>
</tbody>
</table>
</div>
<h4>Evidence Supporting Applicability of this Relationship</h4>
<div>
</div>
<div>
</div>
<div>
</div>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Taxonomic applicability</strong>: </span><span style="font-size:11pt">Oviparous vertebrates synthesize yolk precursor proteins that are transported in the circulation for uptake by developing oocytes. Many invertebrates also synthesize vitellogenins that are taken up into developing oocytes via active transport mechanisms. However, invertebrate vitellogenins are transported in hemolymph or via other transport mechanisms rather than plasma.</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Life stage</strong>: </span><span style="font-size:11pt">This KER is applicable to all life stages following the differentiation of the liver. Embryos prior to liver differentiation should not be included.</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Sex</strong>: </span><span style="font-size:11pt">This KER is applicable to both sexes. However, as males do not have the ability to clear plasma VTG via uptake into the oocytes the outcome is more likely to be problematic in males. Therefore, this KER has more relevance in males both in the context of monitoring for exogenous estrogens and potential biological consequences of elevated VTG.</span></span></span></p>
<h4>Evidence Supporting this KER</h4>
<strong>Biological Plausibility</strong>
<p>Original text - unknown contributor</p>
<p><em>High level of physiological plausibility in fish. </em></p>
<p> </p>
<p><span style="color:#333399">Added by C. Baettig on June 24, 2024</span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">The liver is the primary source of VTG synthesis and production and after it is synthesized it is secreted into the blood (Wallace, 1985). Vitellogenin transcription and translation results in protein production, although there is a delay between expression of <em>vtg</em> and actual production/detection of VTG (e.g., Korte et al. 2000).</span></span></span></p>
<strong>Empirical Evidence</strong>
<p> </p>
<ul>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">In male tilapia, 48 hours after 17β-estradiol (E2) treatment, <em>vtg</em> hepatic mRNA expression was elevated as was plasma VTG (Davis et al., 2008).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">In time course studies an increase in <em>vtg</em> mRNA synthesis precedes increases in plasma VTG concentration. For example, a study using male fathead minnows injected with E2, vtg mRNA was detected in the liver within 4 hours, reached a maximum around 48 hours, and returned to normal levels after 6 days. Plasma VTG was detectable within 16 hours of treatment, reached maximum levels at about 72 hours, and did not return to normal levels for at least 18 days (Korte et al., 2000).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Similar results were observed in a flow-through experiment using sheepshead minnows exposed to E2 and p-nonylphenol. A dose dependent increase in hepatic vtg mRNA initially occurred followed by plasma VTG increase. Their results further supported that hepatic <em>vtg</em> mRNA rapidly diminishes after termination of estrogenic exposure, but plasma VTG clearance is concentration and time dependent (Hemmer et al., 2002).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Bowman et al. (2000) also found a time lag between <em>vtg</em>, which was elevated after 4 hours while induction of plasma VTG wasn’t detected until 24 hours in male sheepshead minnows injected with E2.</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">During waterborne exposures to 17α-ethinylestradiol (EE2), male fathead minnows showed a strong increase of <em>vtg</em> mRNA within 3 days (first sampling time point in the study), which remained elevated for the entirety of the 35-day exposure. Although plasma VTG was first detectable on day 3 it did not significantly increase until day 14 further illustrating the lag between <em>vtg</em> mRNA and plasma increase (Schmid et al., 2002).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">In male fathead minnows exposed to E2 and FC-10 diol for 21 days, expression of hepatic <em>vtg</em> was significantly increased as was the plasma VTG (Ankley et al. in prep).</span></span></span></li>
</ul>
<strong>Uncertainties and Inconsistencies</strong>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="color:#333399"><span style="font-size:11pt">There are no known inconsistencies between these KERs which are not readily explained on the basis of the expected dose, temporal, and incidence relationships between these two KERs. This applies across a significant body of literature in which these two KEs have been measured.</span></span></span></p>
<h4>Quantitative Understanding of the Linkage</h4>
<strong>Response-response relationship</strong>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="color:#333399"><span style="font-size:11pt">Models and statistical relationships that define quantitative relationships between circulating E2 concentrations and circulating VTG concentrations have been developed (Ankley et al., 2008; Li et al., 2011; Murphy et al., 2009; Murphy et al., 2005). However, much of this work has focused on decreased VTG as a function of decreased E2, rather than induction.</span></span></span></p>
<strong>Time-scale</strong>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="color:#333399"><span style="font-size:11pt">Due to the timeline between induction of mRNA transcription, translation, and the appearance of protein in plasma, as well as variable rates of uptake of VTG from plasma into oocytes, a precise quantitative relationship describing all steps of vitellogenesis transcription/translation has not been described. </span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="color:#333399"><span style="font-size:11pt">However, studies in fish suggest that that the temporal lag between mRNA transcription and increased plasma concentrations takes place within 24 hours. For example, in fish injected with E2 there is generally an increase of <em>vtg</em> mRNA beginning around 4 hours whereas plasma VTG isn’t measurable until 16-24 hours (Bowman et al., 2000; Korte et al., 2000). Additionally, in waterborne exposure of estrone (E1) in juvenile rainbow trout, elevated vtg mRNA occurred on day 4 of exposure while plasma VTG was elevated on day 5 (Osachoff et al., 2016).</span></span></span></p>
<strong>Known Feedforward/Feedback loops influencing this KER</strong>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">There is no known feedback as plasma VTG does not appear to regulate expression levels in the liver.</span></span></span></p>
<h4>References</h4>
<ul>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Ankley, G. T., Miller, D. H., Jensen, K. M., Villeneuve, D. L., & Martinović, D. (2008). Relationship of plasma sex steroid concentrations in female fathead minnows to reproductive success and population status. <em>Aquatic Toxicology</em>,<em> 88</em>(1), 69-74. <a href="https://doi.org/https:/doi.org/10.1016/j.aquatox.2008.03.005" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.aquatox.2008.03.005</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Bowman, C. J., Kroll, K. J., Hemmer, M. J., Folmar, L. C., & Denslow, N. D. (2000). Estrogen-induced vitellogenin mRNA and protein in sheepshead minnow (Cyprinodon variegatus). <em>General and Comparative Endocrinology</em>,<em> 120</em>(3), 300-313. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Davis, L. K., Pierce, A. L., Hiramatsu, N., Sullivan, C. V., Hirano, T., & Grau, E. G. (2008). Gender-specific expression of multiple estrogen receptors, growth hormone receptors, insulin-like growth factors and vitellogenins, and effects of 17β-estradiol in the male tilapia (Oreochromis mossambicus). <em>General and Comparative Endocrinology</em>,<em> 156</em>(3), 544-551. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Hemmer, M. J., Bowman, C. J., Hemmer, B. L., Friedman, S. D., Marcovich, D., Kroll, K. J., & Denslow, N. D. (2002). Vitellogenin mRNA regulation and plasma clearance in male sheepshead minnows,(Cyprinodon variegatus) after cessation of exposure to 17β-estradiol and p-nonylphenol. <em>Aquatic Toxicology</em>,<em> 58</em>(1-2), 99-112. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Korte, J. J., Kahl, M. D., Jensen, K. M., Pasha, M. S., Parks, L. G., LeBlanc, G. A., & Ankley, G. T. (2000). Fathead minnow vitellogenin: Complementary DNA sequence and messenger RNA and protein expression after 17β‐estradiol treatment. <em>Environmental Toxicology and Chemistry: An International Journal</em>,<em> 19</em>(4), 972-981. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Li, Z., Kroll, K. J., Jensen, K. M., Villeneuve, D. L., Ankley, G. T., Brian, J. V., Sepúlveda, M. S., Orlando, E. F., Lazorchak, J. M., Kostich, M., Armstrong, B., Denslow, N. D., & Watanabe, K. H. (2011). A computational model of the hypothalamic - pituitary - gonadal axis in female fathead minnows (Pimephales promelas) exposed to 17α-ethynylestradiol and 17β-trenbolone. <em>BMC Systems Biology</em>,<em> 5</em>(1), 63. <a href="https://doi.org/10.1186/1752-0509-5-63" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1186/1752-0509-5-63</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Murphy, C. A., Rose, K. A., Rahman, M. S., & Thomas, P. (2009). Testing and applying a fish vitellogenesis model to evaluate laboratory and field biomarkers of endocrine disruption in Atlantic croaker (Micropogonias undulatus) exposed to hypoxia. <em>Environmental toxicology and chemistry</em>,<em> 28</em>(6), 1288-1303. <a href="https://doi.org/https:/doi.org/10.1897/08-304.1" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1897/08-304.1</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Murphy, C. A., Rose, K. A., & Thomas, P. (2005). Modeling vitellogenesis in female fish exposed to environmental stressors: predicting the effects of endocrine disturbance due to exposure to a PCB mixture and cadmium. <em>Reproductive Toxicology</em>,<em> 19</em>(3), 395-409. <a href="https://doi.org/https:/doi.org/10.1016/j.reprotox.2004.09.006" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.reprotox.2004.09.006</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Osachoff, H. L., Brown, L. L. Y., Tirrul, L., van Aggelen, G. C., Brinkman, F. S. L., & Kennedy, C. J. (2016). Time course of hepatic gene expression and plasma vitellogenin protein concentrations in estrone-exposed juvenile rainbow trout (Oncorhynchus mykiss). <em>Comparative Biochemistry and Physiology Part D: Genomics and Proteomics</em>,<em> 19</em>, 112-119. <a href="https://doi.org/https:/doi.org/10.1016/j.cbd.2016.02.002" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.cbd.2016.02.002</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Schmid, T., Gonzalez-Valero, J., Rufli, H., & Dietrich, D. R. (2002). Determination of vitellogenin kinetics in male fathead minnows (Pimephales promelas). <em>Toxicology Letters</em>,<em> 131</em>(1), 65-74. <a href="https://doi.org/https:/doi.org/10.1016/S0378-4274(02)00043-7" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/S0378-4274(02)00043-7</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Wallace, R. A. (1985). Vitellogenesis and oocyte growth in nonmammalian vertebrates. <em>Oogenesis</em>, 127-177. </span></span></li>
</ul>
</div>
<div>
<h4><a href="/relationships/254">Relationship: 254: Increase, Plasma vitellogenin concentrations leads to Increase, Renal pathology due to VTG deposition</a></h4>
<td><a href="/aops/29">Estrogen receptor agonism leading to reproductive dysfunction</a></td>
<td>adjacent</td>
<td>High</td>
<td></td>
</tr>
<tr>
<td><a href="/aops/536">Estrogen receptor agonism leading to reduced survival and population growth due to renal failure</a></td>
<td>adjacent</td>
<td>Moderate</td>
<td>Low</td>
</tr>
</tbody>
</table>
</div>
<h4>Evidence Supporting Applicability of this Relationship</h4>
<div>
</div>
<div>
</div>
<div>
</div>
<p>Original text - unknown contribution</p>
<p><em>Publish studies specifically relate to fish, although it is plausible that the same response may occur in the aquatic life-stages of amphibians. </em></p>
<p> </p>
<p><span style="color:#333399">Added by C. Baettig on June 24, 2024</span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="color:#333399"><span style="font-size:11pt"><strong>Taxonomic applicability</strong>: Oviparous vertebrates that synthesize yolk precursor proteins and have functional kidneys.</span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="color:#333399"><span style="font-size:11pt"><strong>Life stage</strong>:<strong> </strong>This KER is applicable to all life stages following the differentiation of the liver and kidney.</span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="color:#333399"><span style="font-size:11pt"><strong>Sex</strong>:<strong> </strong>This KER is applicable to both sexes.</span></span></span></p>
<h4>Evidence Supporting this KER</h4>
<strong>Biological Plausibility</strong>
<p>Original text - unknown contribution</p>
<p><em>High level of biological plausibility in fish. </em></p>
<p><span style="color:#333399">Added by C. Baettig on June 24, 2024</span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">When large quantities of VTG are circulating hyalin material can accumulate in the kidneys which can cause significant pathology (Folmar et al., 2001; Herman & Kincaid, 1988; Palace et al., 2002). Additionally, eosinophilic material is known to accumulate in kidney tubules and has been proposed to be due to high circulating VTG (Hahlbeck et al., 2004). Similarly, cilia proliferation observed in renal tubules is assumed to be related to increased absorption of circulating vitellogenin (Zha et al., 2008).</span></span></span></p>
<strong>Empirical Evidence</strong>
<p>Original text - unknown contribution</p>
<p><em>Laboratory in vivo aquatic exposures of fish (fathead minnow) to 17alpha-ethinylestradiol led to renal pathology within 16 weeks, concomitant with macroscopic evidence of osmoregulatory dysfunction and morbidity (Laenge et al., 2001). </em></p>
<p><span style="color:#333399">Added by C. Baettig on June 24, 2024</span></p>
<p> </p>
<ul>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Male summer flounder injected with 17β-estradiol (E2) had increased levels of circulating VTG. The accumulation of VTG resulted in obstruction or rupture of renal glomeruli (Folmar et al., 2001).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Male rare minnow exposed to 17α-ethinylestradiol (EE2) and 4-nonylphenol (NP) had significantly increased plasma VTG concentrations, as did females after EE2 exposure. This resulted in hemorrhages in male kidney tubules, hypertrophy of tubular epithelia, and accumulated eosinophilic material in renal tissue (Zha et al., 2007).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Elevated levels of VTG and kidney hypertrophy in juvenile three-spined sticklebacks was observed after exposure to E2 and EE2 (Hahlbeck et al., 2004).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Male fathead minnows experimentally exposed to EE2 within a whole lake experiment showed 9000-fold higher VTG concentrations than fish captured from the same lake prior to the EE2 additions. Edema in the interstitium between kidney tubules and eosinophilic deposits in the kidney tubule lumen were also observed in the EE2-exposed male fatheads (Palace et al., 2002).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">After exposure to bisphenol A VTG levels increased in fathead minnows resulting in glomerular epithelial cell hyperplasia, hyaline droplets in glomeruli, glomerular mesangial membrane thickening, intravascular proteinaceous fluid, tubular dilation, and dilation of Bowman’s spaces (Mihaich et al., 2012).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Fathead minnow embryos exposed to EE2 exhibited increased whole body VTG levels and tubular degeneration and dilation and glomerulonephritis/glomerulosclerosis was observable after 16 weeks (Länge et al., 2001).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">In male fathead minnows exposed to E2 and an estrogenic PFAS, FC-10 diol, for 21 days plasma VTG was significantly increased. Neuropathy in the kidneys of diol-exposed fish was observed, specifically tubule dilation, tubule protein, enlarged glomeruli, glomerular protein, and thickened basement membranes. Additionally, interstitial and intravascular proteinaceous fluid was significantly elevated (Ankley et al. in prep).</span></span></span></li>
</ul>
<strong>Uncertainties and Inconsistencies</strong>
<p>Original text - unknown contribution</p>
<p><em>None that the author of this entry is aware of. </em></p>
<p><span style="color:#333399">Added by C. Baettig on June 24, 2024</span></p>
<p> </p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Although the accumulation of hyalin material/lipoprotein within the kidneys has been confirmed to be partially caused by accumulated VTG, some of the accumulated proteins do not respond to VTG antibody (e.g., Folmar et al., 2001). Because male fish will also express other estrogen inducible proteins such as vitelline envelope and zona radiata some renal pathology could be caused by these related proteins rather than VTG (Johan Hyllner et al., 1994; Oppen‐Berntsen et al., 1994).</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Proliferative kidney disease (PKD) in fish caused by the parasite <em>Tetracapsuloides bryosalmonae</em> results in significant kidney pathology. However, when PKD infection took place under simultaneous exposure to EE2, kidney pathology was less pronounced despite the fact that hepatic <em>vtg</em> was elevated in fish exposed to the estrogen (Bailey et al., 2019; Rehberger et al., 2020).</span></span></span></p>
<h4>References</h4>
<p>Herman, R.L., Kincaid, H.L. (1988) Pathological effects of orally administered 17beta-estradiol to rainbow trout. Aquaculture 72:165–172</p>
<p>Länge, R., Hutchinson, T.H., Croudace, C.P., Siegmund, F., Schweinfurth, H., Hampe, P., Panter, G.H., Sumpter, J.P. (2001) Effects of the synthetic estrogen 17 alpha-ethinylestradiol on the life-cycle of the fathead minnow (Pimephales promelas). Environ Toxicol Chem 20:1216-1227</p>
<p> </p>
<ul>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Bailey, C., von Siebenthal, E. W., Rehberger, K., & Segner, H. (2019). Transcriptomic analysis of the impacts of ethinylestradiol (EE2) and its consequences for proliferative kidney disease outcome in rainbow trout (Oncorhynchus mykiss). <em>Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology</em>,<em> 222</em>, 31-48. <a href="https://doi.org/https:/doi.org/10.1016/j.cbpc.2019.04.009" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.cbpc.2019.04.009</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Folmar, L. C., Gardner, G. R., Schreibman, M. P., Magliulo-Cepriano, L., Mills, L. J., Zaroogian, G., Gutjahr-Gobell, R., Haebler, R., Horowitz, D. B., & Denslow, N. D. (2001). Vitellogenin-induced pathology in male summer flounder (Paralichthys dentatus). <em>Aquatic Toxicology</em>,<em> 51</em>(4), 431-441. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Hahlbeck, E., Katsiadaki, I., Mayer, I., Adolfsson-Erici, M., James, J., & Bengtsson, B.-E. (2004). The juvenile three-spined stickleback (Gasterosteus aculeatus L.) as a model organism for endocrine disruption II—kidney hypertrophy, vitellogenin and spiggin induction. <em>Aquatic Toxicology</em>,<em> 70</em>(4), 311-326. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Herman, R. L., & Kincaid, H. L. (1988). Pathological effects of orally administered estradiol to rainbow trout. <em>Aquaculture</em>,<em> 72</em>(1-2), 165-172. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Johan Hyllner, S., Silvers, C., & Haux, C. (1994). Formation of the vitelline envelope precedes the active uptake of vitellogenin during oocyte development in the rainbow trout, Oncorhynchus mykiss. <em>Molecular Reproduction and Development</em>,<em> 39</em>(2), 166-175. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Länge, R., Hutchinson, T. H., Croudace, C. P., Siegmund, F., Schweinfurth, H., Hampe, P., Panter, G. H., & Sumpter, J. P. (2001). Effects of the synthetic estrogen 17α‐ethinylestradiol on the life‐cycle of the fathead minnow (Pimephales promelas). <em>Environmental Toxicology and Chemistry: An International Journal</em>,<em> 20</em>(6), 1216-1227. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Mihaich, E., Rhodes, J., Wolf, J., van der Hoeven, N., Dietrich, D., Hall, A. T., Caspers, N., Ortego, L., Staples, C., & Dimond, S. (2012). Adult fathead minnow, Pimephales promelas, partial life‐cycle reproductive and gonadal histopathology study with bisphenol A. <em>Environmental toxicology and chemistry</em>,<em> 31</em>(11), 2525-2535. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Oppen‐Berntsen, D., Olsen, S., Rong, C., Taranger, G., Swanson, P., & Walther, B. (1994). Plasma levels of eggshell zr‐proteins, estradiol‐17β, and gonadotropins during an annual reproductive cycle of Atlantic salmon (Salmo salar). <em>Journal of Experimental Zoology</em>,<em> 268</em>(1), 59-70. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Palace, V. P., Evans, R. E., Wautier, K., Baron, C., Vandenbyllardt, L., Vandersteen, W., & Kidd, K. (2002). Induction of vitellogenin and histological effects in wild fathead minnows from a lake experimentally treated with the synthetic estrogen, ethynylestradiol. <em>Water Quality Research Journal</em>,<em> 37</em>(3), 637-650. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Rehberger, K., Wernicke von Siebenthal, E., Bailey, C., Bregy, P., Fasel, M., Herzog, E. L., Neumann, S., Schmidt-Posthaus, H., & Segner, H. (2020). Long-term exposure to low 17α-ethinylestradiol (EE2) concentrations disrupts both the reproductive and the immune system of juvenile rainbow trout, Oncorhynchus mykiss. <em>Environment International</em>,<em> 142</em>, 105836. <a href="https://doi.org/https:/doi.org/10.1016/j.envint.2020.105836" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.envint.2020.105836</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Zha, J., Sun, L., Zhou, Y., Spear, P. A., Ma, M., & Wang, Z. (2008). Assessment of 17α-ethinylestradiol effects and underlying mechanisms in a continuous, multigeneration exposure of the Chinese rare minnow (Gobiocypris rarus). <em>Toxicology and applied pharmacology</em>,<em> 226</em>(3), 298-308. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Zha, J., Wang, Z., Wang, N., & Ingersoll, C. (2007). Histological alternation and vitellogenin induction in adult rare minnow (Gobiocypris rarus) after exposure to ethynylestradiol and nonylphenol. <em>Chemosphere</em>,<em> 66</em>(3), 488-495. </span></span></li>
</ul>
</div>
<div>
<h4><a href="/relationships/3258">Relationship: 3258: Increase, Renal pathology due to VTG deposition leads to Increased Mortality</a></h4>
<td><a href="/aops/536">Estrogen receptor agonism leading to reduced survival and population growth due to renal failure</a></td>
<td>adjacent</td>
<td>Moderate</td>
<td>Low</td>
</tr>
</tbody>
</table>
</div>
<h4>Evidence Supporting Applicability of this Relationship</h4>
<div>
</div>
<div>
</div>
<div>
</div>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Taxonomic applicability</strong>: All vertebrates with functional kidneys.</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Life stage</strong>: This KER is applicable to all life stages following the differentiation of the kidney.</span></span></span></p>
<p><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt"><strong>Sex</strong>: This KER is applicable to both sexes.</span></span></span></p>
<h4>Evidence Supporting this KER</h4>
<strong>Biological Plausibility</strong>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="color:#333399"><span style="font-size:11pt">The kidneys perform a suite of physiological roles that are critical for organismal homeostasis including waste excretion, osmoregulation, and fluid homeostasis (Preuss, 1993). The renal system can incur damage from a variety of sources which can lead to a loss of renal functions such as decreased glomerular filtration rate or impaired clearance of waste products which can lead to death (McKee & Wingert, 2015). </span></span></span></p>
<p><span style="font-family:Arial,Helvetica,sans-serif"><span style="color:#333399"><span style="font-size:11pt">For example, in fish exposed to estrogenic compounds there is evidence that excessive production of vitellogenin (VTG), which leads to renal failure, increases mortality in fish (Herman & Kincaid, 1988). Generally, the molecular mass of proteins in glomerular filtrate are lower than albumin but when proteins like VTG are deposited in the kidneys they cannot be resorbed and the excess protein can lead to glomerular rupturing or hemorrhaging (Tojo & Kinugasa, 2012). Ultimately these pathologies can cause acute renal failure resulting in mortality.</span></span></span></p>
<strong>Empirical Evidence</strong>
<ul>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Male summer flounder injected with 17β-estradiol (E2) had increased levels of circulating VTG. The accumulation of VTG resulted in obstruction or rupture of renal glomeruli. Glomerular injury including immunoreactive hyalin material within the glomerular capsule, increased drainage into Bowman’s space and renal tubules. Mortality observed after E2 treatment likely resulted from acute renal failure associated with excessive VTG accumulation in the kidney (Folmar et al., 2001).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">High mortality was observed in rainbow trout fed E2. The accumulation of circulating VTG most likely resulted in hypertrophy of the kidneys (Herman & Kincaid, 1988).</span></span></span> </li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Abdel-Tawwab et al. (2020) found that in European sea bass fed dietary zearalenone combined with exposure to a pathogen, <em>Vibrio alginolyticus, </em>increased mortality. A depletion of serum total protein, albumin, and globulin was observed in in zearalenone fed fish which resulted in kidney dysfunction and ultimately increased mortality.</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Exposure to microcystin-LR (MC-LR) resulted in kidney lesions consisting of coagulative tubular necrosis with a dilation of Bowman's space and caused mortality in rainbow trout (Kotak et al., 1996). Mortality is most likely due to MC-LR resulting in significantly dysregulating proteins related to ionic regulation (Shahmohamadloo et al., 2022).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Laboratory in vivo aquatic exposures of fathead minnow to EE2 led to renal pathology within 16 weeks, concomitant with macroscopic evidence of osmoregulatory dysfunction and morbidity (Länge et al., 2001).</span></span></span> </li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">Proliferative kidney disease caused by <em>Tetracapsuloides bryosalmonae</em> in salmonid fish result in significant kidney lesions and often resulted in mortality (e.g., Bettge et al., 2009; Schmidt-Posthaus et al., 2015; Sterud et al., 2007).</span></span></span></li>
<li><span style="color:#333399"><span style="font-family:Arial,Helvetica,sans-serif"><span style="font-size:11pt">In male fathead minnows exposed to the estrogenic PFAS FC-10 diol for 21 days neuropathy in the kidneys was observed, specifically tubule dilation, tubule protein, enlarged glomeruli, glomerular protein, and thickened basement membranes. Additionally, interstitial and intravascular proteinaceous fluid was significantly elevated. Elevated mortality in males was also observed (Ankley et al. in prep).</span></span></span></li>
</ul>
<h4>References</h4>
<ul>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Abdel-Tawwab, M., Khalifa, E., Diab, A. M., Khallaf, M. A., Abdel-Razek, N., & Khalil, R. H. (2020). Dietary garlic and chitosan alleviated zearalenone toxic effects on performance, immunity, and challenge of European sea bass, Dicentrarchus labrax, to Vibrio alginolyticus infection. <em>Aquaculture International</em>,<em> 28</em>, 493-510. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Bettge, K., Wahli, T., Segner, H., & Schmidt-Posthaus, H. (2009). Proliferative kidney disease in rainbow trout: time-and temperature-related renal pathology and parasite distribution. <em>Diseases of aquatic organisms</em>,<em> 83</em>(1), 67-76. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Folmar, L. C., Gardner, G. R., Schreibman, M. P., Magliulo-Cepriano, L., Mills, L. J., Zaroogian, G., Gutjahr-Gobell, R., Haebler, R., Horowitz, D. B., & Denslow, N. D. (2001). Vitellogenin-induced pathology in male summer flounder (Paralichthys dentatus). <em>Aquatic Toxicology</em>,<em> 51</em>(4), 431-441. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Herman, R. L., & Kincaid, H. L. (1988). Pathological effects of orally administered estradiol to rainbow trout. <em>Aquaculture</em>,<em> 72</em>(1-2), 165-172. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Kotak, B. G., Semalulu, S., Fritz, D. L., Prepas, E. E., Hrudey, S. E., & Coppock, R. W. (1996). Hepatic and renal pathology of intraperitoneally administered microcystin-LR in rainbow trout (Oncorhynchus mykiss). <em>Toxicon</em>,<em> 34</em>(5), 517-525. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Länge, R., Hutchinson, T. H., Croudace, C. P., Siegmund, F., Schweinfurth, H., Hampe, P., Panter, G. H., & Sumpter, J. P. (2001). Effects of the synthetic estrogen 17α‐ethinylestradiol on the life‐cycle of the fathead minnow (Pimephales promelas). <em>Environmental Toxicology and Chemistry: An International Journal</em>,<em> 20</em>(6), 1216-1227. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">McKee, R. A., & Wingert, R. A. (2015). Zebrafish Renal Pathology: Emerging Models of Acute Kidney Injury. <em>Current Pathobiology Reports</em>,<em> 3</em>(2), 171-181. <a href="https://doi.org/10.1007/s40139-015-0082-2" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1007/s40139-015-0082-2</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Preuss, H. G. (1993). Basics of renal anatomy and physiology. <em>Clinics in laboratory medicine</em>,<em> 13</em>(1), 1-11. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Schmidt-Posthaus, H., Hirschi, R., & Schneider, E. (2015). Proliferative kidney disease in brown trout: Infection level, pathology and mortality under field conditions. <em>Diseases of aquatic organisms</em>,<em> 114</em>(2), 139-146. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Shahmohamadloo, R. S., Ortiz Almirall, X., Simmons, D. B. D., Poirier, D. G., Bhavsar, S. P., & Sibley, P. K. (2022). Fish tissue accumulation and proteomic response to microcystins is species-dependent. <em>Chemosphere</em>,<em> 287</em>, 132028. <a href="https://doi.org/https:/doi.org/10.1016/j.chemosphere.2021.132028" style="color:#0563c1; text-decoration:underline">https://doi.org/https://doi.org/10.1016/j.chemosphere.2021.132028</a> </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Sterud, E., Forseth, T., Ugedal, O., Poppe, T. T., Jørgensen, A., Bruheim, T., Fjeldstad, H.-P., & Mo, T. A. (2007). Severe mortality in wild Atlantic salmon Salmo salar due to proliferative kidney disease (PKD) caused by Tetracapsuloides bryosalmonae (Myxozoa). <em>Diseases of aquatic organisms</em>,<em> 77</em>(3), 191-198. </span></span></li>
<li><span style="font-size:11pt"><span style="font-family:Calibri,sans-serif">Tojo, A., & Kinugasa, S. (2012). Mechanisms of glomerular albumin filtration and tubular reabsorption. <em>Int J Nephrol</em>,<em> 2012</em>, 481520. <a href="https://doi.org/10.1155/2012/481520" style="color:#0563c1; text-decoration:underline">https://doi.org/10.1155/2012/481520</a> </span></span></li>
</ul>
<p> </p>
</div>
<div>
<h4><a href="/relationships/2013">Relationship: 2013: Increased Mortality leads to Decrease, Population growth rate</a></h4>
<td><a href="/aops/312">Acetylcholinesterase Inhibition leading to Acute Mortality via Impaired Coordination & Movement</a></td>
<td>adjacent</td>
<td></td>
<td></td>
</tr>
<tr>
<td><a href="/aops/16">Acetylcholinesterase inhibition leading to acute mortality</a></td>
<td>adjacent</td>
<td>Moderate</td>
<td>Moderate</td>
</tr>
<tr>
<td><a href="/aops/155">Deiodinase 2 inhibition leading to increased mortality via reduced posterior swim bladder inflation</a></td>
<td>adjacent</td>
<td>Moderate</td>
<td>Moderate</td>
</tr>
<tr>
<td><a href="/aops/156">Deiodinase 2 inhibition leading to increased mortality via reduced anterior swim bladder inflation</a></td>
<td>adjacent</td>
<td>Moderate</td>
<td>Moderate</td>
</tr>
<tr>
<td><a href="/aops/157">Deiodinase 1 inhibition leading to increased mortality via reduced posterior swim bladder inflation </a></td>
<td>adjacent</td>
<td>Moderate</td>
<td>Moderate</td>
</tr>
<tr>
<td><a href="/aops/158">Deiodinase 1 inhibition leading to increased mortality via reduced anterior swim bladder inflation</a></td>
<td>adjacent</td>
<td>Moderate</td>
<td>Moderate</td>
</tr>
<tr>
<td><a href="/aops/159">Thyroperoxidase inhibition leading to increased mortality via reduced anterior swim bladder inflation</a></td>
<td>adjacent</td>
<td>Moderate</td>
<td>Moderate</td>
</tr>
<tr>
<td><a href="/aops/363">Thyroperoxidase inhibition leading to altered visual function via altered retinal layer structure</a></td>
<td>adjacent</td>
<td>Moderate</td>
<td>Moderate</td>
</tr>
<tr>
<td><a href="/aops/364">Thyroperoxidase inhibition leading to altered visual function via decreased eye size</a></td>
<td>adjacent</td>
<td></td>
<td></td>
</tr>
<tr>
<td><a href="/aops/365">Thyroperoxidase inhibition leading to altered visual function via altered photoreceptor patterning</a></td>
<td>adjacent</td>
<td></td>
<td></td>
</tr>
<tr>
<td><a href="/aops/399">Inhibition of Fyna leading to increased mortality via decreased eye size (Microphthalmos)</a></td>
<td>adjacent</td>
<td>High</td>
<td>High</td>
</tr>
<tr>
<td><a href="/aops/410">GSK3beta inactivation leading to increased mortality via defects in developing inner ear</a></td>
<td>adjacent</td>
<td>High</td>
<td>High</td>
</tr>
<tr>
<td><a href="/aops/536">Estrogen receptor agonism leading to reduced survival and population growth due to renal failure</a></td>
<td>adjacent</td>
<td>Moderate</td>
<td>Moderate</td>
</tr>
<tr>
<td><a href="/aops/564">DBDPE-induced inhibition of mitochondrial complex Ⅰ leading to population decline via neurotoxicity and metabotoxicity.</a></td>
<td>adjacent</td>
<td>High</td>
<td>High</td>
</tr>
</tbody>
</table>
</div>
<h4>Evidence Supporting Applicability of this Relationship</h4>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong><span style="color:black">Taxonomic</span></strong><span style="color:black">: All organisms must survive to reproductive age in order to reproduce and sustain populations. The additional considerations related to survival made above are applicable to other fish species in addition to zebrafish and fathead minnows with the same reproductive strategy (r-strategist as described in the theory of MaxArthur and Wilson (1967). The impact of reduced survival on population size is even greater for k-strategists that invest more energy in a lower number of offspring.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong><span style="color:black">Life stage</span></strong><span style="color:black">: Density dependent effects start to play a role in the larval stage of fish when free-feeding starts (Hazlerigg et al., 2014).</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><strong><span style="color:black">Sex</span></strong><span style="color:black">: This linkage is independent of sex.</span></span></span></span></p>
<p> </p>
<h4>Key Event Relationship Description</h4>
<p><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Increased mortality in the reproductive population may lead to a declining population. This depends on the excess mortality due to the applied stressor and the environmental parameters such as food availability and predation rate. Most fish species are r-strategist, meaning they produce a lot of offspring instead of investing in parental care. This results in natural high larval mortality causing only a small percentage of the larvae to survive to maturity. If the excess larval mortality due to a stressor is small, the population dynamics might result in constant population size. Should the larval excess be more significant, or last on the long-term, this will affect the population. To calculate the long-term persistence of the population, population dynamic models should be used.</span></span></span></span></p>
<h4>Evidence Supporting this KER</h4>
<p><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Survival rate is an obvious determinant of population size and is therefore included in population modeling (e.g., Miller et al., 2020).</span></span></span></span></p>
<strong>Biological Plausibility</strong>
<ul>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif">Survival to reproductive maturity is a parameter of demographic significance. Assuming resource availability (i.e., food, habitat, etc.) is not limiting to the extant population, sufficient mortality in the reproductive population may ultimately lead to declining population trajectories.</span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif">Under some conditions, reduced larval survival may be compensated by reduced predation and increased food availability, and therefore not result in population decline (Stige et al., 2019).</span></span></li>
</ul>
<strong>Empirical Evidence</strong>
<ul>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif">According to empirical data, combined with population dynamic models, feeding larvae are the crucial life stage in zebrafish (and other r-strategists) for the regulation of the population. (Schäfers et al., 1993)</span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif">In fathead minnow, natural survival of early life stages has been found to be highly variable and influential on population growth (Miller and Ankley, 2004)</span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif">Rearick et al. (2018) used data from behavioural assays linked to survival trials and applied a modelling approach to quantify changes in antipredator escape performance of larval fathead minnows in order to predict changes in population abundance. This work was done in the context of exposure to an environmental oestrogen. Exposed fish had delayed response times and slower escape speeds, and were more susceptible to predation. Population modelling showed that this can result in population decline.</span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif">In the context of fishing and fisheries, ample evidence of a link between increased mortality and a decrease of population size has been given. Important insights can result from the investigation of optimum modes of fishing that allow for maintaining a population (Alekseeva and Rudenko, 2018). Jacobsen and Essington (2018) showed the impact of varying predation mortality on forage fish populations.</span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif">Boreman (1997) reviewed methods for comparing the population-level effects of mortality in fish populations induced by pollution or fishing.</span></span></li>
</ul>
<strong>Uncertainties and Inconsistencies</strong>
<ul>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">The extent to which larval mortality affects population size could depend on the fraction of surplus mortality compared to a natural situation.</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">There are scenarios in which individual mortality may not lead to declining population size. These include instances where populations are limited by the availability of habitat and food resources, which can be replenished through immigration. Effects of mortality in the larvae can be compensated by reduced competition for resources (Stige et al., 2019).</span></span></span></li>
<li><span style="font-size:12pt"><span style="font-family:Calibri,sans-serif"><span style="color:black">The direct impact of pesticides on migration behavior can be difficult to track in the field, and documentation of mortality during migration is likely underestimated (Eng 2017).</span></span></span></li>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Beaudouin, R., Goussen, B., Piccini, B., Augustine, S., Devillers, J., Brion, F., Pery, A.R., 2015. An individual-based model of zebrafish population dynamics accounting for energy dynamics. PloS one 10, e0125841.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Boreman J. 1997. Methods for comparing the impacts of pollution and fishing on fish populations. Transactions of the American Fisheries Society. 126(3):506-513.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Eng, M.L., Stutchbury, B.J.M. & Morrissey, C.A. Imidacloprid and chlorpyrifos insecticides impair migratory ability in a seed-eating songbird. Sci Rep 7, 15176 (2017)</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Hazlerigg, C.R., Lorenzen, K., Thorbek, P., Wheeler, J.R., Tyler, C.R., 2012. Density-dependent processes in the life history of fishes: evidence from laboratory populations of zebrafish Danio rerio. PLoS One 7, e37550.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Jacobsen NS, Essington TE. 2018. Natural mortality augments population fluctuations of forage fish. Fish and Fisheries. 19(5):791-797.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">MacArthur, R., Wilson, E., 1967. The Theory of Island Biogeography. Princeton: Princeton Univ. Press. 203 p.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Miller, D.H., Ankley, G.T., 2004. Modeling impacts on populations: fathead minnow (Pimephales promelas) exposure to the endocrine disruptor 17β-trenbolone as a case study. Ecotoxicology and Environmental Safety 59, 1-9.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Miller, D.H., Clark, B.W., Nacci, D.E. 2020. A multidimensional density dependent matrix population model for assessing risk of stressors to fish populations. Ecotoxicology and environmental safety 201, 110786</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Pinceel, T., Vanschoenwinkel, B., Brendonck, L., Buschke, F., 2016. Modelling the sensitivity of life history traits to climate change in a temporary pool crustacean. Scientific reports 6, 29451.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Rearick, D.C., Ward, J., Venturelli, P., Schoenfuss, H., 2018. Environmental oestrogens cause predation-induced population decline in a freshwater fish. Royal Society open science 5, 181065.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Schäfers, C., Oertel, D., Nagel, R., 1993. Effects of 3, 4-dichloroaniline on fish populations with differing strategies of reproduction. In: Braunbeck, T. , Hanke, W and Segner, H. (eds) Ecotoxicology and Ecophysiology, VCH, Weinheim, 133-146.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Stige, L.C., Rogers, L.A., Neuheimer, A.B., Hunsicker, M.E., Yaragina, N.A., Ottersen, G., Ciannelli, L., Langangen, Ø., Durant, J.M., 2019. Density‐and size‐dependent mortality in fish early life stages. Fish and Fisheries 20, 962-976.Hazlerigg, C.R.E., Tyler, C.R., Lorenzen, K., Wheeler, J.R., Thorbek, P., 2014. Population relevance of toxicant mediated changes in sex ratio in fish: An assessment using an individual-based zebrafish (Danio rerio) model. Ecological Modelling 280, 76-88.</span></span></span></span></p>
<p style="text-align:start"><span style="font-size:medium"><span style="font-family:Calibri,sans-serif"><span style="color:#000000"><span style="color:black">Stige, L.C., Rogers, L.A., Neuheimer, A.B., Hunsicker, M.E., Yaragina, N.A., Ottersen, G., Ciannelli, L., Langangen, O., Durant, J.M., 2019. Density- and size-dependent mortality in fish early life stages. Fish and Fisheries 20, 962-976.</span></span></span></span></p>