GENETIC-ANALYSIS OF STERILE MUTANTS IN THE DPY-5 UNC-13 (I) GENOMIC REGION OF CAENORHABDITIS-ELEGANS

Essential genes were identified in the 1.5-map unit dpy-5 unc-13 regio n of chromosome I in the Caenorhabditis elegans genome by rescuing let hal mutations using the duplication sDp2. In this paper, we report the mapping and complementation testing of lethal mutations, 45 of which identify 18 new, essential genes. This analysis brings the number of e ssential genes defined by the sDp2 rescue of lethal mutants to 97; 64 of these map between dpy-5 and unc-13. 61% of these essential genes ar e identified by more than one allele. Positioning of the mutations was done using the breakpoints of six duplications. The mutant phenotypes of 14 loci essential for fertility were characterized by Nomarski mic roscopy and DAPI staining. None of the mutants were rescued by wild-ty pe male sperm. The cytological data showed that four genes produced mu tants with defects in gonadogenesis, let-395, let-603, let-605 and let -610. Mutations in seven genes, let-355, let-367, let-384, let-513, le t-544, let-545 and let-606, affected germ cell proliferation or gameto genesis. Mutants for the remaining three genes, let-370, let-599 and l et-604: produced eggs that failed to develop or hatch, thereby acting as maternal effect lethals. We observed a nonrandom distribution of ar rest phenotypes with regard to map position.