Worm Breeder's Gazette 9(1): 29
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.
At the meetings in May, we reported the isolation of mutator (mut) strains that exhibit elevated frequencies of spontaneous Tc1 excision and transposition (Abstracts of the 1985 CSH Meeting). These mutants were isolated because they exhibit elevated frequencies of reversion to wild type of an unc-54 ::Tc1 mutant. Southern blots indicate that mutator-induced Unc-54+ revertants contain precise or nearly precise excisions of Tc1 from unc-54. Individual mutator strains (we have 8 independent isolates) have frequencies of Unc-54+ reversion that are increased 10- to 200-fold above their non-mutator parent. Each of the mutator strains also exhibits elevated frequencies of TcI transposition. For individual mutator strains, the frequencies of spontaneous unc-22 mutants (twitchers) obtained was 7- to 50-fold greater than in the non-mutator parent. The strongest of our mutator strains have unc-22 mutation frequencies of approximately 2 x 10+E-3. All tested mutator-induced unc-22 mutants are unstable, reverting to wild type at frequencies in excess of 10+E-3. Southern blots demonstrate that the majority (13/17) of mutator induced unc-22 mutants contain ~1.6 kb insertions in unc-22 (presumed to be Tc1). Of the remaining four, two contain as yet uncharacterized DNA rearrangements in the unc-22 region, and two appear unchanged from wild type. Southern blots also confirm that all tested mutator- induced unc-22+ revertants contain precise or nearly precise excisions of Tc1 from unc-22.Each of the mutators exhibits a semi-dominant Him ( high incidence of males) phenotype. The Him phenotypes of four mutator induced mutants have been mapped. Three are linked to unc-54 I. For one of these three (mut-3(r456), contained in strain TR638) the mutator phenotype is also linked to unc-54 I. (The Mut phenotype is defined as elevated frequencies of reversion of Tc1-induced mutants.) The Him phenotype of the fourth mutator (mut-2(r459), contained in the ever-popular strain TR679) is linked to dpy-10 II. The mutator and the Him phenotype of TR679 generally cosegregate in crosses, so we anticipate that the mutator phenotype will also map to LGII. Experiments to demonstrate this are in progress.