PHOTOLYASE ACTIVITIES OF ELYSIA-TUCA, BURSATELLA-LEACHII, AND HAMINAEA-ANTILLARUM (MOLLUSCA, OPISTHOBRANCHIA)

The recent reduction in stratospheric ozone has led to speculation tha t marine organisms may be harmed by increased exposure to midultraviol et radiation (UVB). Elysia tuca Marcus, Bursatella leachii Rang and Ha minaea antillarum d'Orbigny are opisthobranch slugs which dwell in sha llow marine waters and are exposed to different amounts Of biologicall y damaging solar UVB. As adults, E. tuca are exposed to the highest le vels of solar UVB, B. leachii are exposed to moderate levels of solar UVB, and H. antillarum are exposed to low levels of solar UVB. As larv ae, the planktotrophic B. leachii are probably exposed to the most sol ar UVB, followed by the lecithotrophic larvae of E. tuca and then the direct developing larvae of H. antillarum, which have no planktonic st age of development. In this study, the capacity of photolyase-mediated DNA repair for each species was determined to examine interspecific v ariation in the ability of these marine slugs to repair UV-induced DNA damage. A DNA repair assay involving incubation of a UV-damaged plasm id with slug extracts containing photoreactivating enzyme was used. Pa rtially purified E. tuca photolyase extracts repaired 19.82 +/- 7.15% (mean +/- so) of the damaged plasmid DNA; B. leachii photolyase extrac ts repaired 4.59 +/- 1.92% of the damaged plasmid DNA; H. antillarum p hotolyase extracts repaired 20.32 +/- 9.22% of the damaged plasmid DNA . The results of nonorthogonal planned comparisons tests between speci es showed a statistically significant difference (p < 0.05) in the com parison between the photorepair capacities of B. leachii and E. tuca p hotolyase extracts, and in the comparison between the photorepair capa cities of B. leachii and H. antillarum photolyase extracts, but no sig nificance in the comparison between the photorepair capacities of E. t uca and H. antillarum photolyase extracts.