A CYTOGENETICAL ANALYSIS OF STERILE MUTANTS INCAENORHABDITIS ELEGANS

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Abstract
The regulation of gametogenesis in the hermaphrodite and proterandrous nematode C. elegans was studied through the analysis of nonconditional sterile mutants. To investigate the mechanisms which allow the 2 gametogenetic phases to succeed each other in the same ovotestis, 3 mutants were studied cytogenetically. Two of the mutants exhibit only the spermatocyte phase and the 3rd shows a greatly reduced and disturbed oogenesis. These 3 mutations all produce large decreases in ovotestis size and gonocyte number. Each of the 3 is monofactorial, recessive, autosomal and independent. Homozygous mutant males are also sterile. The gametogenesis phases which could be disturbed by mutation were determined by cytological analysis of the ovotestis of 12 other sterile strains. These phases occur during mitotic divisions of the genital primordium, zygotene chromosome pairing, male meiosis and spermiogenesis, oogenesis induction and oocyte maturation. These steps of gametogenesis need a wild-type genic activity to occur normally. Spermatogenesis and oogenesis are 2 genetically independent processes. Oogenesis is rather autononmous and its induction depends on a hormonal factor.