Worm Breeder's Gazette 12(3): 45 (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.
The gene let-653 has been previously mapped and found to lie >0.05 map units from unc-22 and to the right of dpy-20 on linkage group IV (Clark 1992). Two mutant alleles have been isolated, one of which causes developmental arrest at the end of the larval stage L1 .The other allele causes developmental arrest within the larval stage L2 .The developmental arrest occurs just after the appearance of a large vacuole just close to the pharynx. The appearance of the vacuole is consistent with the absence or loss function of the excretory cell or of its pore cell. Although it has been previously thought that the role of this excretory apparatus is one predominantly of osmoregulation, altering the salt concentration of the worm media does not suppress lethality nor the appearance of the vacuole.
Germline transformation experiments have demonstrated that the cosmid C29E6 can rescue the lethal phenotype and therefore contains a functional copy of the let-653 gene. The cosmids which overlap C29E6 ,namely B0033 , C11F2 and C46F3 ,are currently being used in germline transformation experiments; the co-injection of a plasmid bearing the dominant rol-6 mutant allele su1006 acting as positive marker for the injected DNA. This will allow us to define more accurately the position of the let-653 gene.