This work was funded by an Eastern Washington University Start Something Big Grant to JJM (http://sites.ewu.edu/foundation/resources/startsomething- big-grant/); National Institutes of Health (http://www.nih.gov/) grant R01 GM072639 to CFB and DRD, National Institutes of Health grant 5 R01 GM087628-02 to DRD and SE; PSU Faculty Enhancement grant to SE (http://www.pdx.edu/oaa/faculty-enhancement-grants) and American Heart Association Predoctoral Fellowship 11PRE4880069 to KAH (http://my.americanheart.org/professional/Research/FundingOpportunities/Funding-Opportunities_UCM_316909_ SubHomePage.jsp).
Caenorhabditis elegans -- Genetics, Oxidative stress -- Molecular aspects, Mutation (Biology)
We explored the relationship between relaxed selection, oxidative stress, and spontaneous mutation in a set of mutationaccumulation (MA) lines of the nematode Caenorhabditis elegans and in their common ancestor. We measured steady-state levels of free radicals and oxidatively damaged guanosine nucleosides in the somatic tissues of five MA lines for which nuclear genome base substitution and GC-TA transversion frequencies are known. The two markers of oxidative stress are highly correlated and are elevated in the MA lines relative to the ancestor; point estimates of the per-generation rate of mutational decay (DM) of these measures of oxidative stress are similar to those reported for fitness-related traits. Conversely, there is no significant relationship between either marker of oxidative stress and the per-generation frequencies of base substitution or GC-TA transversion. Although these results provide no direct evidence for a causative relationship between oxidative damage and base substitution mutations, to the extent that oxidative damage may be weakly mutagenic in the germline, the case for condition-dependent mutation is advanced.
Joyner-Matos, J., Hicks, K. A., Cousins, D., Keller, M., Denver, D. R., Baer, C. F., and Estes, S. (2013). Evolution of a Higher Intracellular Oxidizing Environment in Caenorhabditis elegans under Relaxed Selection. PLOS ONE, 8(6), e65604.