Worm Breeder's Gazette 12(3): 94 (June 15, 1992)

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.

Isolation and Characterization of Balancers for LG III

Ann Marie Howell, Helen I. Stewart, Heather-Ann Nethery, David L. Baillie

Institute of Molecular Biology and Biochemistry, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada

As part of the genetic toolkit project, we have been isolating and characterizing balancers for LG III. These will be used in screens for recessive lethal mutations and the generation of deficiencies. The translocation eT1 (711,V) balances most of the right half of LG III, so we concentrated our attention on the left half.

sDp3 is a free duplication of an approximately 20 map unit interval which includes at least half of the gene cluster of LG III. A strain with the genotype sDp3 / dpy-17 unc-32 +/ dpy-17 + lin-12 was constructed and used to screen for EMS-induced lethals. Fifty-four lethal mutations induced on the dpy-17 unc-32 chromosome were isolated after screening 2836 mutagenized chromosomes. Mapping of these lethals is in progress. So far, six map to the left of dpy-17 and eleven map to the right of dpy-17 .This is consistent with the position of the gene cluster on LG III. This strain has also been used to isolate lethals induced with 2000R of gamma radiation.

In order to balance the left end of LG III, we screened for suppression of crossing over between unc-45 and dpy-1 after treatment with 2000R of gamma radiation. We have recovered two homozygous viable crossover suppressors, sC1 and sC2 . sC1 eliminates recombination in this region. We are currently determining the boundaries of crossover suppression of sC1 and plan to induce markers on it to make it useful for lethal screens.

Funded by the NIH National Center for Research Resources.