The
tbc-2 gene encodes for a putative Rab GTPase activating protein. Mutations in
tbc-2 result in the accumulation of large late endosomes in the intestine, as well as trafficking phenotypes in oocytes and coelomocytes (see abstract by Chotard et al.). To identify genes required for the
tbc-2(-) intestinal phenotype we performed a pilot genetic screen for suppressors of the large late endosome phenotype. One of the suppressor mutations,
vh8, is male in character. The
vh8 animals lack a hermaphrodite vulva and have a male tail displaying varying degrees of development. The somatic gonad appears to be male, however it develops both sperm and oocyte-like cells. Loss of function mutations in the tra genes (
tra-1, -2, and -3), "Transform" XX hermaphrodites into phenotypic males, and hypomorphic
tra-1 XX pseudo-males can develop oocytes similar to
vh8. To determine if
vh8 could be an allele of one of the tra genes, we tested if
vh8 is balanced by the translocations hT2 I; III and nT1 IV;V, or the chromosomal inversion mIn1 II, which balance
tra-1,
tra-3 and
tra-2 respectively. We found that
vh8 is balanced by hT2, but not nT1 or mIn1, suggesting that
vh8 might be an allele of
tra-1. Consistent with this idea we found that
tra-1(
e1099) could also suppress the
tbc-2(
tm2241) intestinal phenotype. Finally, we found that
vh8 fails to complement
tra-1(
e1099) for the Tra male tail phenotype and thus
vh8 is likely a new allele of
tra-1. TRA-1 is a GLI-type transcription factor, suggesting that it acts indirectly to regulate the
tbc-2(-) endocytic phenotype in the intestine. In hermaphrodites TRA-1 functions to suppress male traits and thus promotes hermaphrodite specific development. Therefore, a simple explanation would be that the
tbc-2(-) phenotype is hermaphrodite specific. However we find that
tbc-2(-) males also display the large intestinal endosome phenotype indicating that the phenotype is not sex specific and suggesting that
tra-1 might function independently of sex determination to affect trafficking in the intestine. It has previously been shown that
tra-1 is involved in the development of the somatic gonad in both males and hermaphrodites and therefore could regulate other aspects of animal development/physiology in both sexes. We are keen to determine if mutations in other tra genes can also suppress the
tbc-2(-) intestinal phenotype, or if TRA-1 is functioning independently of the sex determination pathway to affect endocytic trafficking in the intestine.