Primary sex determination in the nematode C. elegans.
Most nematodes have XO male/XX female sex determination. C. elegans is anomalous, having XX hermaphrodites rather than females. The hermaphrodite condition appears to result from the modification of a basic male/female sex-determination system, which permits both spermatogenesis and oogenesis to occur within a female soma. This modification is achieved by a germ-line-specific control acting at one step in a cascade of autosomal regulatory genes, which respond to X-chromosome dosage and direct male, female, or hermaphrodite development. Mutations of one of these genes can be used to construct artificial strains with ZZ male/WZ female sex determination. Primary sex determination normally depends on the ratio of X chromosomes to autosomes, as in Drosophila, and there appear to be multiple sites on the X chromosome that contribute to this ratio. Also, as in Drosophila, X-chromosome expression is compensated to equalize gene activity in XX and XO animals. Interactions between dosage compensation and sex determination are described and discussed.
D000818:Animals; D002107:Caenorhabditis / Q000235:genetics*; D002874:Chromosome Mapping; D012734:Disorders of Sex Development; D004303:Dosage Compensation, Genetic; D005260:Female; D008297:Male; D009154:Mutation; D010641:Phenotype; D011123:Polyploidy; D012732:Sex Determination Analysis; D014960:X Chromosome