Worm Breeder's Gazette 8(3): 41
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.
We have sought suppressors of dpy-26(n199) as a means of obtaining mutations in genes that interact with dpy-26 or that are involved in general with regulating the expression of X-linked genes. dpy-26(n199) is a maternal-effect, hermaphrodite-specific lethal mutation. XX animals derived from XX animals heterozygous for the dpy mutant allele are slightly Dpy; XX animals derived from homozygous animals are usually dead (occasionally there are escapers). dpy-26 mutations also result in a recessive Him phenotype producing 5% XO animals; these males are essentially wild type. In order to obtain suppressors of n199 we selected for hermaphrodite survivors from animals homozygous for n199. In particular we mutagenized the strain dpy-26(n199) )/nT1 (IV:V) n752 with EMS, picked F1 animals displaying the unc-22 twitcher phenotype and scored their progeny for viable hermaphrodites. In this procedure s7 is used as a visible marker to identify animals homozygous for n199. nT1 balances the right side of chromosome IV. The most frequent class of putative suppressors turned out to be animals which had acquired a new unc-22 mutation on the nT1 chromosome. However, one mutant was isolated which acts as a dominant suppressor of all the dpy-26-associated phenotypes. This mutation has the following additional properties: 1) It also suppresses the closely- linked mutation unc-31(e169). 2) A true breeding suppressed strain cannot be isolated. 3) When suppressed and nonsuppressed hermaphrodites are stained with DAPI and their chromosomes examined a very large free duplication appears in the oocytes of the suppressed hermaphrodites but is absent from the oocytes of the nonsuppressed hermaphrodites. The duplication (yDp1) is probably a breakdown product of nT1 and may contain portions of both chromosomes IV and V. We are presently mapping the chromosomal location and extent of yDp1.