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Relationship: 202

Title

A descriptive phrase which clearly defines the two KEs being considered and the sequential relationship between them (i.e., which is upstream, and which is downstream). More help

Increase, Mutations leads to Increase, Heritable mutations in offspring

Upstream event
The causing Key Event (KE) in a Key Event Relationship (KER). More help
Downstream event
The responding Key Event (KE) in a Key Event Relationship (KER). More help

Key Event Relationship Overview

The utility of AOPs for regulatory application is defined, to a large extent, by the confidence and precision with which they facilitate extrapolation of data measured at low levels of biological organisation to predicted outcomes at higher levels of organisation and the extent to which they can link biological effect measurements to their specific causes. Within the AOP framework, the predictive relationships that facilitate extrapolation are represented by the KERs. Consequently, the overall WoE for an AOP is a reflection in part, of the level of confidence in the underlying series of KERs it encompasses. Therefore, describing the KERs in an AOP involves assembling and organising the types of information and evidence that defines the scientific basis for inferring the probable change in, or state of, a downstream KE from the known or measured state of an upstream KE. More help

AOPs Referencing Relationship

AOP Name Adjacency Weight of Evidence Quantitative Understanding Point of Contact Author Status OECD Status
Alkylation of DNA in male pre-meiotic germ cells leading to heritable mutations adjacent High Moderate Carole Yauk (send email) Open for citation & comment WPHA/WNT Endorsed

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KER.In general, this will be dictated by the more restrictive of the two KEs being linked together by the KER.  More help
Term Scientific Term Evidence Link
mouse Mus musculus High NCBI
human Homo sapiens High NCBI

Sex Applicability

An indication of the the relevant sex for this KER. More help

Life Stage Applicability

An indication of the the relevant life stage(s) for this KER.  More help

Key Event Relationship Description

Provides a concise overview of the information given below as well as addressing details that aren’t inherent in the description of the KEs themselves. More help

If a mutation arises in spermatogonial stem cells and does not influence cellular function, the mutation can become fixed and/or propagated within the stem cell population. Mutations that do not affect sperm maturation will persist through the succeeding stages of spermatogenesis and will be found in the mature sperm of the organism throughout its reproductive lifespan. Mutations can also occur in differentiating spermatogonia; however, once the sperm generated by these dividing spermatogonia are ejaculated there will be no ‘record’ of the induced mutation. Mutations that impair spermatogenesis or the viability of the cell will be lost via apoptosis and cell death, potentially contributing to decreased fertility. Mutations that do not impact sperm motility, morphology or ability to penetrate the zona pellucida (or other important sperm parameters), and that are present in mature sperm, may be transmitted to the egg resulting in the development of an offspring with a mutation. Thus, increased incidence of mutations in germ cells leads to increased incidence of mutations in the offspring. There is a great deal of evidence demonstrating that exposure to a variety of DNA alkylating agents induces mutations in male spermatogenic cells.

Evidence Collection Strategy

Include a description of the approach for identification and assembly of the evidence base for the KER.  For evidence identification, include, for example, a description of the sources and dates of information consulted including expert knowledge, databases searched and associated search terms/strings.  Include also a description of study screening criteria and methodology, study quality assessment considerations, the data extraction strategy and links to any repositories/databases of relevant references.Tabular summaries and links to relevant supporting documentation are encouraged, wherever possible. More help

Evidence Supporting this KER

Addresses the scientific evidence supporting KERs in an AOP setting the stage for overall assessment of the AOP. More help
Biological Plausibility
Addresses the biological rationale for a connection between KEupstream and KEdownstream.  This field can also incorporate additional mechanistic details that help inform the relationship between KEs, this is useful when it is not practical/pragmatic to represent these details as separate KEs due to the difficulty or relative infrequency with which it is likely to be measured.   More help

Evolution requires heritable mutations that are transmitted to offspring via parental gametes. This is the primary mechanism by which an offspring would have a sequence variant in every single one of its cells that is not found in its parents. Indeed, as stated in a recent review in Science by Shendura and Aikey "Germline mutations are the principal cause of heritable disease and the ultimate source of evolutionary change." Thus, this KER is supported by substantive understanding of genetics and evolution, with heritable germ cell mutations forming the basis for the selective evolution of species.

In addition, in toxicology, a large body of literature demonstrates that exposure to specific genotoxic chemicals during pre-meiotic stages of spermatogenesis leads to mutations in both the sperm and the offspring, supporting that mutations occurring in sperm fertilize the egg and result in offspring with mutations (reviewed in Demarini 2012; Marchetti and Wyrobek 2005; Yauk et al. 2012). Indeed, ENU is used as a tool in genetics to create offspring carrying mutations for the purposes of understanding gene function ( e.g., http://www.riken.jp/en/research/labs/brc/mutagen_genom). In these studies, male mice are mutagenized by exposure to ENU and mated to females. The offspring of these males have a much higher incidence of mutation; the function of new mutations occurring in genes in these offspring is used to study gene function.

Thus, overall this KER is biologically plausible and widely understood.

Uncertainties and Inconsistencies
Addresses inconsistencies or uncertainties in the relationship including the identification of experimental details that may explain apparent deviations from the expected patterns of concordance. More help

There are no inconsistencies in the data for this KER, although the data are limited. There is a possibility that mutations can arise in the early embryo instead of in the spermatogenic cells. However, given the study designs for this type of work (where > 42 days pass prior to sperm collection or mating – see OECD TG488 for the time-series required for transgene mutation analysis in sperm), it is unlikely that this contributes significantly. Limitations in technology currently prevent the analyses required to describe the incidence of mutations in sperm versus offspring, but this is a future research direction. It should be noted that the locations and types of mutations would influence the probably of transmission; this relationship has not been confirmed empirically and limits extrapolation across studies applying different endpoints.

Known modulating factors

This table captures specific information on the MF, its properties, how it affects the KER and respective references.1.) What is the modulating factor? Name the factor for which solid evidence exists that it influences this KER. Examples: age, sex, genotype, diet 2.) Details of this modulating factor. Specify which features of this MF are relevant for this KER. Examples: a specific age range or a specific biological age (defined by...); a specific gene mutation or variant, a specific nutrient (deficit or surplus); a sex-specific homone; a certain threshold value (e.g. serum levels of a chemical above...) 3.) Description of how this modulating factor affects this KER. Describe the provable modification of the KER (also quantitatively, if known). Examples: increase or decrease of the magnitude of effect (by a factor of...); change of the time-course of the effect (onset delay by...); alteration of the probability of the effect; increase or decrease of the sensitivity of the downstream effect (by a factor of...) 4.) Provision of supporting scientific evidence for an effect of this MF on this KER. Give a list of references.  More help
Response-response Relationship
Provides sources of data that define the response-response relationships between the KEs.  More help
Time-scale
Information regarding the approximate time-scale of the changes in KEdownstream relative to changes in KEupstream (i.e., do effects on KEdownstream lag those on KEupstream by seconds, minutes, hours, or days?). More help
Known Feedforward/Feedback loops influencing this KER
Define whether there are known positive or negative feedback mechanisms involved and what is understood about their time-course and homeostatic limits. More help

Domain of Applicability

A free-text section of the KER description that the developers can use to explain their rationale for the taxonomic, life stage, or sex applicability structured terms. More help

Mutation is the underlying source of evolution and occurs in every species. Theoretically, any sexually reproducing organism (i.e., producing gametes) can acquire mutations in their gametes and transmit these to descendants. Thus, the present KER is relevant to any species producing sperm.

References

List of the literature that was cited for this KER description. More help

Barnett, L.B., R.W. Tyl, B.S. Shane, M.D. Shelby and S.E. Lewis (2002), "Transmission of mutations in the lacI transgene to the offspring of ENU-treated Big Blue male mice", Environ. Mol. Mutagen., 40(4): 251-257.

Brooks, T.M. and S.W. Dean (1997), "The detection of gene mutation in the tubular sperm of Muta Mice following a single intraperitoneal treatment with methyl methanesulphonate or ethylnitrosourea", Mutat. Res., 388(2-3): 219-222.

Demarini, D.M. (2012), "Declaring the existence of human germ-cell mutagens", Environ. Mol. Mutagen., 53(3): 166-172.

Dubrova, Y.E., P. Hickenbotham, C.D. Glen, K. Monger, H.P. Wong and R.C. Barber (2008), "Paternal exposure to ethylnitrosourea results in transgenerational genomic instability in mice", Environ. Mol. Mutagen., 49(4): 308-311.

Kong, A., M.L. Frigge, G. Masson, S. Besenbacher, P. Sulem, G. Magnusson, S.A. Gudjonsson, A. Sigurdsson, A. Jonasdottir, W.S. Wong, G. Sigurdsson, G.B. Walters, S. Steinberg, H. Helgason, G. Thorleifsson, D.F. Gudbjartsson, A. Helgason, O.T. Magnusson, U. Thorsteinsdottir and K. Stefansson K. (2012), "Rate of de novo mutations and the importance of father's age to disease risk", Nature, 488(7412): 471-475.

Lewis, S.E., L.B. Barnett, B.M. Sadler and M.D. Shelby (1991), "ENU mutagenesis in the mouse electrophoretic specific-locus test, 1. Dose-response relationship of electrophoretically-detected mutations arising from mouse spermatogonia treated with ethylnitrosourea", 'Mutat. Res., 249(2): 311-315.

Liegibel, U.M. and P. Schmezer (1994), "Detection of the two germ cell mutagens ENU and iPMS using the LacZ/transgenic mouse mutation assay" Mutat. Res., 341(1):17-28.

Marchetti, F. and A.J. Wyrobek (2005), "Mechanisms and consequences of paternally-transmitted chromosomal abnormalities", Birth Defects Res C Embryo Today, 75(2): 112-129.

Mattison, J.D., L.B. Penrose and B. Burlinson (1997), "Preliminary results of ethylnitrosourea, isopropyl methanesulphonate and methyl methanesulphonate activity in the testis and epididymal spermatozoa of Muta Mice", Mutat. Res. 388(2-3): 123-7.

O'Brien, J.M., A. Williams, J. Gingerich, G.R. Douglas, F. Marchetti and C.L. Yauk (2013), "No evidence for transgenerational genomic instability in the F1 or F2 descendants of Muta™Mouse males exposed to N-ethyl-N-nitrosourea", Mutat Res., 741-742:11-7

Paul,C. and B. Robaire (2013), "Ageing of the male germ line", Nat. Rev. Urol., 10(4): 227-234.

Shendura, J. and M. Akey (2015), "The origins, determinants, and consequences of human mutations", Science, 349(6255): 1478-1483.

Sun, J.X., A. Helgason, G. Masson, S.S. Ebenesersdottir, H. Li, S. Mallick, S. Gnerre, N. Patterson, A. Kong, D. Reich and K. Stefansson (2012), "A direct characterization of human mutation based on microsatellites", Nat. Genet., 44(10): 1161-1165.

Swayne, B.G., A. Kawata, N.A. Behan, A. Williams, M.G. Wade, A.J. Macfarlane and C.L. Yauk (2012), "Investigating the effects of dietary folic acid on sperm count, DNA damage and mutation in Balb/c mice", Mutat. Res., 737(1-2): 1-7.

Vilarino-Guell, C., A.G. Smith and Y.E. Dubrova (2003), "Germline mutation induction at mouse repeat DNA loci by chemical mutagens", 'Mutat. Res., 526(1-2): 63-73.

Yauk, C.L., Y.E. Dubrova, G.R. Grant and A.J. Jeffreys (2002), "A novel single molecule analysis of spontaneous and radiation-induced mutation at a mouse tandem repeat locus", Mutat Res., 500(1-2): 147-156.

Yauk, C.L., L.J. Argueso, S.S. Auerbach, P. Awadalla, S.R. Davis, D.M. Demarini, G.R. Douglas, Y.E. Dubrova, R.K. Elespuru, T.M. Glover, B.F. Hales , M.E. Hurles, C.B. Klein, J.R. Lupski, D.K. Manchester, F. Marchetti, A. Montpetit, J.J. Mulvihill, B. Robaire, W.A. Robbins, G.A. Rouleau, D.T. Shaughnessy, C.M. Somers, J.G. Taylor 6th, J. Trasler, M.D. Waters, T.E. Wilson, K.L. Witt and J.B. Bishop (2013), "Harnessing genomics to identify environmental determinants of heritable disease" Mutation Research, 752(1): 6-9.