Worm Breeder's Gazette 12(5): 55 (February 1, 1993)
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.
sli-1 is a negative regulator of the vulval induction pathway in C. elegans. Reduction-of-function mutations in let-23 ,a C. elegans homolog of the mammalian EGF receptor, cause a vulvaless (Vul) phenotype. While mutations in sli-1 alone are silent (i.e., wild-type vulva), let-23 ; sli-1 double mutants display a greater responsiveness to the inductive signal, either having a hyperinduced vulval phenotype (Hin) or a less severe Vul phenotype. Thus, the wild-type function of sli-1 appears to be the negative regulation of vulval induction; a sli-1 mutation increases the number of cells forming vulval tissue. We have rescued the sli-1 mutant phenotype by microinjection with the cosmid T18D5 .
Genetic mapping showed that sli-1 lies between egl-17 and unc-1 .The RFLP stP41 was mapped near and to the left of unc-1 (Anne Villeneuve, pers. comm.). We assumed that stP41 was near unc-1 ,that the contig extended to the left end of chromosome X, and that egl-17 was located at the end of the chromosome. We therefore chose the centrally located cosmids F02G3 , T18D5 , F25H6 , F25E2 .These cosmids were injected individually into let-23 ( sy1 ); sli-1 ( sy143 )double mutants along with rol-6 DNA as a transgenic marker, and stable transgenic lines were recovered and scored. Microinjection of the cosmid T18D5 rescued the Hin phenotype of the let-23 ; sli-1 parental strain and yielded transgenic progeny with the Vul phenotype typical of a let-23 mutation. Cosmids F02G3 , F25H6 ,and F25E2 failed to rescue the Hin phenotype in transgenic animals. An additional allele of sli-1 , sy129 ,was also rescued by the cosmid T18D5 in let-23 ( sy1 ); sli-1 ( sy129 )double mutants.