Worm Breeder's Gazette 10(1): 70
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
In the last gazette (vol.9 #3,40-41) we reported on our study of spontaneous deletions at the unc-54 locus. One allele, r293, was of particular interest. The deleted material of r293 extends from nucleotide 8217 to 8472 (the base coordinates are from Karn et al. [PNAS 80:4253(1983)]). These 256 nucleotides lie 3' to the amino acid coding sequence. The protein coding sequence of unc-54 ends with a UAA STOP at coordinates 8176-8178. The deletion begins 38 bp downstream of the STOP codon and spans the putative poly-adenylation signal (A2UA3), located at 8344. Although no amino acid coding sequence is missing, the phenotype of a r293 homozygote is that of a typical unc-54 mutant paralyzed, non-egglaying hermaphrodite. The location of the deletion suggested to us that the mutation affects some aspect of mRNA processing such as 3' end formation, message stability, message transport, etc. To investigate the events occurring in this mutant, we have isolated 38 EMS-induced psuedo- revertants. We estimate the frequency of these revertants to be 5X10+E-5 per animal among the F2. This relatively high frequency likely indicates that the gene(s) involved can be mutated in many different ways to give the revertant phenotype, or that more than one gene is involved, or both. Most psuedorevertants contain suppressors that are recessive and unlinked to unc-54: 36 of 37 suppressors are recessive; 35 of 36 suppressors are unlinked to unc-54; one of the revertants is dominant and is closely linked to unc-54. Our suppressors are not sup-3 alleles (sup-3 alleles are semi-dominant suppressors of all unc-54 null alleles). The motility phenotype of the psuedo-revertants is nearly wildtype. Similarily, the phenotype of the suppressors (separated from unc-54(r293)) is approximately wild- type; none appear to be temperature sensitive, but certain suppressors may have a slight defect in vulva morphology. We haven't finished the complementation analysis suppressors, but they comprise at least four complementation groups. We are analyzing mRNA from the various suppressors and unc-54(r293) in order to identify the RNA process being affected.