Worm Breeder's Gazette 9(3): 37
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 analysis of the left end of LGV has included the fine structure analysis of the unc-60 gene, in which we found this gene to be approximately 0.007-0.014 mu. across (WBG Vol. 9(2)). We have now analyzed other complementation groups near the unc-60 gene. The basic idea was to screen heterozygous (unc-60/+) worms for closely linked lethal mutations. The dpy-11 marker was positioned cis to unc-60 to facilitate subsequent three factor mapping. This chromosome was balanced over the deficiency sDf26, which deletes most of the region between unc-60 and dpy-11. The deficiency serves two purposes; l) as a balancer suppressing recombination 2) and to select against mutations not tightly linked to unc-60 or to dpy-11We screened 1222 0.012M EMS treated chromosomes and recovered 13 lethal mutations. We positioned the lethals relative to unc-60 and dpy-11 by three factor mapping. The mutations were then balanced over eT1(III,V) and complementation tested against the set of deficiencies for LGV left (see WBG 9(2):81). Only two of the mutations mapped near unc-60. The rest mapped to the right within 1.7 mu. of dpy-11. This agrees with the observation that unc-60 is in a gene 'sparse' region on the recombination map (see CGC map). Of the 11 lethals that mapped to the dpy-11 region, one was a new deficiency (sDf35) in the unc-23-unc-42 region. Five more mapped to previously unidentified genes. Two of these five mapped outside the eT1 balanced region. Another mutation, s833, is the fourth EMS allele of let-333 while s825 is the fourth EMS allele of let-337; which maps close to dpy-11 (<0.5mu.). None of the mutants mapped between sDf-26 and dpy-11.Both of the mutations near unc-60 mapped to its right. One of the mutations (s819) was found to be allelic to emb-29. This allele is the first non-ts allele of this gene and also positions emb-29 0. 4mu. to the right of unc-60. The second mutation defines a new gene, let-426(s826) and maps 1.1 mu. the right of unc-60. This type of screen, with a large deficiency like sDf26, appears to be useful for isolating mutations in a defined region.