Control of the sperm-oocyte switch in Caenorhabditis elegans hermaphrodites by the fem-3 3' untranslated region

Nature. 1991 Jan 24;349(6307):346-8. doi: 10.1038/349346a0.


In the Caenorhabditis elegans hermaphrodite germ line, sperm and then oocytes are made from a common pool of germ-cell precursors. The decision to differentiate as a sperm or an oocyte is regulated by the sex-determining gene, fem-3. Expression of fem-3 in the hermaphrodite germ line directs spermatogenesis and must be negatively regulated to allow the switch to oogenesis. In adult hermaphrodites (which are producing oocytes), most fem-3 RNA is found in the germ line, consistent with both the requirement for fem-3 in hermaphrodite spermatogenesis and the maternal effects of fem-3 on embryonic sex determination. Whereas loss-of-function mutants in fem-3 produce only oocytes, hermaphrodites carrying any of nine fem-3 gain-of-function (gf) mutations make none; instead sperm are produced continuously and in vast excess over wild-type amounts. Genetic analyses suggest that fem-3(gf) mutations have escaped a negative control required for the switch to oogenesis. Here we report that all nine fem-3(gf) mutants carry sequence alterations in the fem-3 3' untranslated region (3' UTR). There is no increase in the steady-state level of fem-3(gf) RNA over wild-type, but there is an increase in the polyadenylation of fem-3(gf) RNA that is coincident with the unregulated fem-3 activity. Results of a titration experiment support the hypothesis that a regulatory factor may bind the fem-3 3' UTR. We speculate that fem-3 RNA is regulated through its 3' UTR by binding a factor that inhibits translation, and discuss the idea that this control may be part of a more general regulation of maternal RNAs.

Publication types

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

MeSH terms

  • Animals
  • Base Sequence
  • Caenorhabditis / genetics*
  • Cell Differentiation / genetics
  • Disorders of Sex Development*
  • Gene Expression Regulation*
  • Male
  • Molecular Sequence Data
  • Mutation
  • Oocytes / cytology*
  • Oogenesis / genetics
  • Plasmids
  • Protein Biosynthesis
  • RNA / genetics
  • Sex Determination Analysis
  • Spermatogenesis / genetics
  • Spermatozoa / cytology*
  • Transformation, Genetic


  • RNA

Associated data

  • GENBANK/X52371
  • GENBANK/X52372
  • GENBANK/X53984
  • GENBANK/X57181
  • GENBANK/X57182
  • GENBANK/X57183
  • GENBANK/X57184
  • GENBANK/X57657
  • GENBANK/X58548
  • GENBANK/X61719