Worm Breeder's Gazette 12(3): 44 (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.
As part of our laboratory' s ongoing efforts to characterize the gene content and genomic organization of defined regions in the Caenorhabditis elegans genome, we are examining the small (0.05 map unit) interval between let-56 and unc-22 ,in the sDf2 region of Linkage Group IV. It was previously shown (Prasad and Baillie, Genomics 5: 185-198, 1989) that the let-56 - unc-22 region contained transcribed sequences. In addition, the unc-22 sequence (Benian et al., Nature: 342, 45-50, 1989; Benian et al., WBG 11(4):42) includes approximately 13 kilobases of sequence 3' of the unc-22 gene. Analysis of this 3' sequence has identified four predicted open reading frames, including a glucose transporter-like gene (Fields et al., WBG 11(4):43) and a GABA transporter-like gene (Fields, WBG 12(1):38). However previous mutagenesis screens conducted in our laboratory have failed to identify essential genes in this interval. In order to determine whether these putative coding elements are required for C. elegans development, we designed primers specific for each of the four coding elements immediately 3' of unc-22 ,and used PCR (the Barstead and Waterston method) to screen a set of 27 formaldehyde induced unc-22 mutations (17 homozygous viable and 10 homozygous inviable) for deficiencies with breakpoints that subdivide the let-56 - unc-22 interval. Two such deficiencies were recovered. One of these, sDf88 ,is viable as a homozygote. The other, sDf83 ,is inviable as a homozygote. PCR analysis of sDf88 reveals this deficiency deletes unc-22 and three potential coding regions immediately to its left, including the glucose transporter-like gene and the GABA transporter-like gene. We deduce that there are no essential genes within the region of DNA deleted by this deficiency. PCR analysis of sDf83 reveals this deficiency deletes four putative coding elements to the left of unc-22 .Individuals homozygous for this deficiency are arrested late in larval development or as sterile adults. Complementation tests demonstrate that let-56 falls within sDf83 .The breakpoints of sDf83 lie between let-653 and let-56 to the left, and unc-22 and let-52 to the right.
This work was funded by NSERC and MDA of Canada.
Benian et al., Nature: 342, 45-50, 1989
Benian et al., WBG 11(4):42
Fields et al., WBG 11(4):43
Fields, WBG 12(1):38