The
gld-1 tumor suppressor locus is involved in multiple aspects of C. elegans germline development [1,2]. First, the gene is absolutely required for oogenesis. In the absence of
gld-1 activity, germ cells that would normally develop as oocytes enter the meiotic pathway at the appropriate time but then exit pachytene and undergo ectopic proliferation. If
gld-1 function is partially reduced, presumptive female germ cells arrest at the pachytene stage of meiosis or develop as small, defective oocytes. Second, the gene plays a nonessential role in repressing premeiotic germ cell proliferation. Third,
gld-1 promotes, but is not necessary for, adoption of the male fate by germ cells in the hermaphrodite. The
gld-1 gene encodes two proteins (differing by the insertion of three amino acids) that show homology to a family of RNA binding proteins [3]. GLD-1 is most similar to Sam-68/GAPap62, a protein which associates with Src in a cell-cycle dependent manner. Since GLD-1 is localized to the cytoplasm (see abstract by Jones, et al.) it may regulate mRNA stability or translation. To gain insight into the biochemical role(s) of GLD-1, we are screening for suppressors and enhancers of
gld-1 alleles. Our goal is to identify cofactors, regulators and targets of GLD-1. Attempts to recover mutations that suppress either of two nonconditional
gld-1 alleles were unsuccessful. 400,000 mutagenized haploid genomes were screened for dominant suppressors, and 10,000 haploid genomes for recessive suppressors, of the pachytene- arrest phenotype shown by
oz116 ; 700,000 haploid genomes were screened for dominant suppressors, and 50,000 haploid genomes for recessive suppressors, of the abnormal oocyte phenotype produced by
q266. Because these screens employed worm strains that carry
gld-1(+) on a duplication, we used a PCR assay to distinguish true suppressor mutations from rearranged duplications, gene conversion events and other "false positives". We are now trying to isolate temperature-sensitive
gld-1 alleles, which may be more suitable for suppression. Noncomplementation screens have been designed to allow the recovery of dominant enhancers of
gld-1.