xol-1 acts as an early switch in the C. elegans male/hermaphrodite decision

Cell. 1995 Jan 13;80(1):71-82. doi: 10.1016/0092-8674(95)90452-2.


xol-1 is the earliest-acting gene in the known hierarchy that controls C. elegans sex determination and dosage compensation. We show that the primary sex-determining signal (the X/A ratio) directs the choice of sexual fate by regulating xol-1 transcript levels: high xol-1 expression during gastrulation triggers male development, whereas low expression at that time permits hermaphrodite development. Inappropriately high xol-1 expression causes hermaphrodites to activate the male program of development and die from a disruption in dosage compensation. These results demonstrate that xol-1 functions as an early developmental switch to set the choice of sexual fate and suggest that assessment of the X/A ratio occurs only early in embryogenesis to determine sex. Moreover, sdc-2, a gene that must be repressed by xol-1 to ensure male development, may be a direct target of negative regulation by xol-1.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alternative Splicing
  • Amino Acid Sequence
  • Animals
  • Caenorhabditis elegans / embryology
  • Caenorhabditis elegans / genetics*
  • Caenorhabditis elegans Proteins*
  • Cloning, Molecular
  • Disorders of Sex Development / genetics
  • Dosage Compensation, Genetic
  • Embryo, Nonmammalian / metabolism
  • Gastrula / metabolism
  • Gene Expression Regulation, Developmental*
  • Genes, Helminth*
  • Helminth Proteins / chemistry
  • Helminth Proteins / genetics*
  • Helminth Proteins / physiology
  • Male
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • RNA, Helminth / genetics
  • RNA, Helminth / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Recombinant Fusion Proteins / biosynthesis
  • Sex Determination Analysis*


  • Caenorhabditis elegans Proteins
  • Helminth Proteins
  • RNA, Helminth
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • XOL-1 protein, C elegans

Associated data

  • GENBANK/L35129