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Altered, Photoreceptor patterning leads to Altered, Visual function
Key Event Relationship Overview
AOPs Referencing Relationship
|AOP Name||Adjacency||Weight of Evidence||Quantitative Understanding||Point of Contact||Author Status||OECD Status|
|Inhibition of retinaldehyde dehydrogenase leads to population decline||adjacent||Moderate||Moderate||Young Jun Kim (send email)||Under Development: Contributions and Comments Welcome||Under Development|
|Thyroperoxidase inhibition leading to altered visual function via altered photoreceptor patterning||adjacent||Lucia Vergauwen (send email)||Under development: Not open for comment. Do not cite||Under Development|
Life Stage Applicability
Key Event Relationship Description
Photoreceptors in the retina of vertebrates and invertebrates are the cells that are responsible for phototransduction. Photoreceptor subtypes are characterized by different opsins (light-sensitive proteins) that respond to light with different wavelengths. The pattern of photoreceptors in the eyes therefore determines visual function. Alterations in photoreceptor patterning could include altered numbers of photoreceptor subtypes leading to an altered ratio of photoreceptor subtypes and/or altered spatial organization.
Evidence Collection Strategy
Evidence Supporting this KER
Since different photoreceptor subtypes have different opsins that allow for perceiving light of different wavelengths, it is plausible to assume that alterations in photoreceptor patterning such as altered ratios of photoreceptor subtypes affect normal visual function.
Uncertainties and Inconsistencies
Known modulating factors
Known Feedforward/Feedback loops influencing this KER
Domain of Applicability
Although there are important taxonomic differences in opsin genes and in photoreceptor patterning across taxa, it is plausible to assume that the importance of proper photoreceptor patterning for normal visual function is applicable across all vertebrates and invertebrates that have eyes.
It is plausible to assume that alterations of photoreceptor patterning would result in altered visual function across all life stages, but such alterations are most likely to occur during the development of the normal photoreceptor pattern, which occurs in the embryonic phase.
Zebrafish are undifferentiated gonochorists since both sexes initially develop an immature ovary (Maack and Segner, 2003). Immature ovary development progresses until approximately the onset of the third week. Later, in female fish immature ovaries continue to develop further, while male fish undergo transformation of ovaries into testes. Final transformation into testes varies among male individuals, however finishes usually around 6 weeks post fertilization. Effects on visual function resulting from altered photoreceptor patterning during early development are therefore expected to be independent of sex.
Flamarique, I.N., 2013. Opsin switch reveals function of the ultraviolet cone in fish foraging. Proceedings of the Royal Society B-Biological Sciences 280.
Frau, S., Flamarique, I.N., Keeley, P.W., Reese, B.E., Munoz-Cueto, J.A., 2020. Straying from the flatfish retinal plan: Cone photoreceptor patterning in the common sole (Solea solea) and the Senegalese sole (Solea senegalensis). Journal of Comparative Neurology 528, 2283-2307.
Houbrechts, A.M., Vergauwen, L., Bagci, E., Van Houcke, J., Heijlen, M., Kulemeka, B., Hyde, D.R., Knapen, D., Darras, V.M., 2016. Deiodinase knockdown affects zebrafish eye development at the level of gene expression, morphology and function. Molecular and Cellular Endocrinology 424, 81-93.
Maack, G., Segner, H., 2003. Morphological development of the gonads in zebrafish. Journal of Fish Biology 62, 895-906.
Vancamp, P., Houbrechts, A.M., Darras, V.M., 2019. Insights from zebrafish deficiency models to understand the impact of local thyroid hormone regulator action on early development. General and Comparative Endocrinology 279, 45-52.