Computer assisted learning in science education: Edited by Graham Beech. Pp. 185. Pergamon Press, Oxford. 1979. £17.50

Abstract

The recent reduction in stratospheric ozone has led to speculation that marine organisms may be harmed by increased exposure to midultraviolet radiation (UVB). Elysia tuca Marcus, Bursatella leachii Rang and Haminaea antillarum d'Orbigny are opisthobranch slugs which dwell in shallow marine waters and are exposed to different amounts of biologically damaging solar UVB. As adults, E. tuca are exposed to the highest levels 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 larvae, the planktotrophic B. leachii are probably exposed to the most solar UVB, followed by the lecithotrophic larvae of E. tuca and then the direct developing larvae of H. antillarum, which have no planktonic stage of development. In this study, the capacity of photolyase-mediated DNA repair for each species was determined to examine interspecific variation in the ability of these marine slugs to repair UV-induced DNA damage. A DNA repair assay involving incubation of a UV-damaged plasmid with slug extracts containing photoreactivating enzyme was used.Partially purified E. tuca photolyase extracts repaired 19.82 ± 7.15% (mean ± sd) of the damaged plasmid DNA; B. leachii photolyase extracts repaired 4.59 ± 1.92% of the damaged plasmid DNA; H. antillarum photolyase extracts repaired 20.32 ± 9.22% of the damaged plasmid DNA. The results of nonorthogonal planned comparisons tests between species showed a statistically significant difference (p < 0.05) in the comparison between the photorepair capacities of B. leachii and E. tuca photolyase extracts, and in the comparison between the photorepair capacities of B. leachii and H. antillarum photolyase extracts, but no significance in the comparison between the photorepair capacities of E. tuca and H. antillarum photolyase extracts.