THE GENERATION AND GENETIC-ANALYSIS OF SUPPRESSORS OF LETHAL MUTATIONS IN THE CAENORHABDITIS-ELEGANS ROL-3(V) GENE

The Caenorhabditis elegans rol-3(e754) mutation is a member of a gener al class of mutations affecting gross morphology, presumably through d isruption of the nematode cuticle. Adult worms homozygous for rol-3(e7 54) exhibit rotation about their long axis associated with a left-hand twisted cuticle, musculature, gut and ventral nerve cord. Our laborat ory previously isolated 12 recessive lethal alleles of rol-3. All thes e lethal alleles cause an arrest in development at either early or mid -larval stages, suggesting that the rol-3 gene product performs an ess ential developmental function. Furthermore, through the use of the het erochronic mutants lin-14 and lin-29, we have established that the exp ression of rol-3(e754)'s adult specific visible function is not depend ent on the presence of an adult cuticle. In an attempt to understand r ol-3's developmental role we sought to identify other genes whose prod ucts interact with that of rol-3. Toward this end, we generated eight EMS induced and two gamma irradiation-induced recessive suppressors of the temperature sensitive (ts) mid-larval lethal phenotype of rol-3(s 1040ts). These suppressors define two complementation groups srl-1 II and srl-2 III; and, while they suppress the rol-3(s1040) lethality, th ey do not suppress the adult specific visible rolling phenotype. Furth ermore, there is a complex genetic interaction between srl-2 and srl-1 such that srl-2(s2506) fails to complement all srl alleles tested. Th ese results suggest that srl-1 and srl-2 may share a common function a nd, thus, possibly constitute members of the same gene family. Mutatio ns in both srl-1 and srl-2 produce no obvious hermaphrodite phenotypes in the absence of rol-3(s1040ts); however, males homozygous for eithe r srl-1 or srl-2 display aberrant tail morphology. We present evidence suggesting that the members of srl-2 are not allele specific with res pect to their suppression of rol-3 lethality, and that rol-3 may act i n some way to influence proper posterior morphogenesis. Finally, based on our genetic analysis of rol-3 and the srl mutations, we present a model whereby the wild-type products of the srl loci act in a concerte d manner to negatively regulate the rol-3 gene.