title: Evolution of a higher intracellular oxidizing environment in Caenorhabditis elegans under relaxed selection.
abstract: We explored the relationship between relaxed selection, oxidative stress, and spontaneous mutation in a set of mutation-accumulation (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 (ΔM) 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.
authors.affiliation: Department of Biology, Eastern Washington University, Cheney, Washington, United States of America. jmatos@ewu.edu
authors.forename: Joanna
authors.initials: J
authors.lastname: Joyner-Matos
authors.forename: Kiley A
authors.initials: KA
authors.lastname: Hicks
authors.forename: Dustin
authors.initials: D
authors.lastname: Cousins
authors.forename: Michelle
authors.initials: M
authors.lastname: Keller
authors.forename: Dee R
authors.initials: DR
authors.lastname: Denver
authors.forename: Charles F
authors.initials: CF
authors.lastname: Baer
authors.forename: Suzanne
authors.initials: S
authors.lastname: Estes
mesh_terms: D000818:Animals; D005075:Biological Evolution; D017173:Caenorhabditis elegans / Q000378:metabolism*; D009154:Mutation; D018384:Oxidative Stress / Q000502:physiology; D012641:Selection, Genetic