The Caenorhabditis elegans gene sdc-2 controls sex determination and dosage compensation in XX animals.
We have identified a new X-linked gene, sdc-2, that controls the hermaphrodite (XX) modes of both sex determination and X chromosome dosage compensation in Caenorhabditis elegans. Mutations in sdc-2 cause phenotypes that appear to result from a shift of both the sex determination and dosage compensation processes in XX animals to the XO modes of expression. Twenty-eight independent sdc-2 mutations have no apparent effect in XO animals, but cause two distinct phenotypes in XX animals: masculinization, reflecting a defect in sex determination, and lethality or dumpiness, reflecting a disruption in dosage compensation. The dosage compensation defect can be demonstrated directly by showing that sdc-2 mutations cause elevated levels of several X-linked transcripts in XX but not XO animals. While the masculinization is blocked by mutations in sex determining genes required for male development (her-1 and fem-3), the lethality, dumpiness and overexpression of X-linked genes are not, indicating that the effect of sdc-2 mutations on sex determination and dosage compensation are ultimately implemented by two independent pathways. We propose a model in which sdc-2 is involved in the coordinate control of both sex determination and dosage compensation in XX animals and acts in the regulatory hierarchy at a step prior to the divergence of the two pathways.
Nusbaum
C
C
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Meyer
B J
BJ
D000818:Animals; D002107:Caenorhabditis / Q000235:genetics*; D012734:Disorders of Sex Development / Q000235:genetics; D004303:Dosage Compensation, Genetic; D005260:Female; D005796:Genes; D005804:Genes, Lethal; D008040:Genetic Linkage; D008957:Models, Genetic; D009154:Mutation; D010641:Phenotype; D012732:Sex Determination Analysis; D014960:X Chromosome