tra-2 is required for development of female cell fates in C. elegans . It encodes a transmembrane protein that must be repressed in order for male cell fate specification to occur in males and hermaphrodites.
tra-2 is translationally regulated via two regulatory elements (TGEs) in its 3' untranslated region. It has been shown that a factor, DRF, binds specifically to the TGEs, and is thought to negatively regulate translation of
tra-2 . The sex determining gene,
laf-1 , is required for negative regulation of
tra-2 translation and may encode a component of DRF.
laf-1(lf) /+ mutations result in the feminization of hermaphrodite and male animals, and disrupt the control of a reporter transgene by the TGEs.
laf-1 homozygous animals die, suggesting that
laf-1 may regulate other mRNAs besides
tra-2 . The molecular identification of
laf-1 should help to elucidate its role in the translational control of
tra-2 and give insight into other potential regulatory functions of
laf-1 in C. elegans development. We are currently using germline transformation rescue of the
laf-1 lethal phenotype to clone
laf-1 . We have mapped
laf-1 to chromosome III by linkage analysis. An 8.5kb cosmid, T02B2, was found to rescue the
laf-1 lethal phenotype. Furthermore, transgenic animals containing a 2.4kb subclone of T02B2 also rescues the
laf-1 lethality. Interestingly, this region of DNA does not appear to contain any large open reading frames or sequence homology to any known genes. Northern Analysis has yielded preliminary evidence that
laf-1 may correspond to a 1.2kb transcript. RT-PCR and sequencing of
laf-1 null embryos is currently underway to identify the molecular lesion.