Worm Breeder's Gazette 1(1): 22
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.
The primary goal of this work is to collect balancer chromosomes to facilitate the maintenance of recessive lethal mutations in heterozygotes. A paper on work done at the MRC-LMB with D. G. Albertson and S. Brenner has been accepted for publication in 'Genetics.' In that work unlinked duplications of a part of the X chromosome were identified by the following procedure: N2 males were X- irradiated (6,000-8,000 r) and mated with unc-3(E151), a sex-linked mutant. The progeny were screened for wild-type males, which were backcrossed to unc-3. One of the duplications derived in this way, Dp1, proved to be translocated to linkage group V, where it suppresses crossing over between the left half of the Dp1-containing chromosome and its homologue. Dp1 homozygotes grow slowly and are sterile. Dp1 should be a useful balancer for the left half of LGV. Four other duplications are associated with chromosome fragments, as observed cytologically by fluorescence microscopy, and tend to be lost. At least some of the loss appears to occur premeiotically. The frequency of loss is higher in strains homozygous for him-1. The recombination frequencies between two of these duplications and the X have been measured: the frequencies are at least 50 times less than for X-X recombination in the same region. I am currently screening for various autosomal translocations. Candidates have been identified and are being tested further.