Worm Breeder's Gazette 1(2): 21
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We are continuing to study sperm morphology and the process of fertilization in order to characterize temperature sensitive fertilization defective mutants. We have begun studying the process of male fertilization. When wild-type males are mated to young wild- type adult hermaphrodites, the male sperm are deposited in the region of the vulva amidst the hermaphrodite zygotes. Within five hours all the male sperm migrate to the region of the spermatheca. Most surprisingly, five hours after mating some hermaphrodites will begin producing only outcross progeny. Thus not only can male sperm reach the spermatheca rapidly, but when they do so they fertilize oocytes preferentially in spite of the presence of hermaphrodite sperm. We are investigating the basis of both the male sperm motility and the mechanism of preferential fertilization. Sam will get back to studying chemotaxis yet. The temperature sensitive sterility of Che 1 mutants, E1034 and E1035, is not due to deficient sperm production. At 25 C spermatogenesis is normal and the mutant sperm have normal morphology by light and scanning electron microscopy. The sperm contact the oocytes in the hermaphrodite but fertilization does not take place. The mutant sperm are swept into the uterus and expelled when oocytes are laid. We are pursuing the nature of this defect by further scanning and transmission electron microscopy and by immunological and biochemical study of sperm membrane proteins. Several other temperature sensitive sterile mutants in different genes also make sperm that fail to function. We have not been able to resolve the question of whether the sterile defect in these strains is due to the same genetic defect as the behavioral and anatomical defects. Neither the behavioral nor the anatomical defects are temperature sensitive; we have been unable to revert the sterile phenotype and we have been unable to separate the phenotypes by recombination. Other alleles of the behavioral locus isolated in our lab and obtained from Dave Dusenbery are not sterile at 25 C. Perhaps we have a small deletion that alters two linked genes. Does anyone have direct evidence for EMS inducing deletions in C. elegans or any other organism? Does anyone know of a deletion that gives a temperature sensitive phenotype?