COMPARATIVE SENSITIVITY OF SPERM AND EGGS TO ULTRAVIOLET RADIATIONS

Abstract

Sperm of Strongylocentrotus purpuratus, Arbacia punctulata, Dendraster excentricus, and Pateria miniata are more sensitive than eggs as judged by the delay in cleavage of untreated eggs fertilized with such sperm as compared to cleavage of irradiated eggs fertilized with untreated sperm. Sperm and eggs of Urechis caupo, Chaelop-terus pergamentaceus, Nereis limbata and Mactra sp. have a resistance to ultraviolet light of a similar order of magnitude. No satisfactory explanation has been found for the differences observed in those 2 groups of spp. The action spectrum for such delayed cleavage resembles nucleoprotein absorption in the case of irradiated sperm and unconjugated proteins such as albumin in the case of eggs. It is thought that these substances act as the absorbing molecules whose alteration leads to the cleavage delays observed.