Worm Breeder's Gazette 12(3): 64 (June 15, 1992)

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Progress Toward Cloning mes-3

Janet Paulsen, Elizabeth Capowski, Susan Strome

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Department of Biology, Indiana University

A number of loci have been identified that are required for proper germ-line development in C. elegans. The mes-3 locus, identified by five mutant alleles, shows a strict maternal-effect sterile or "grandchildless" phenotype (Capowski et. al. Genetics 129: 1061-1072). The main defect observed in progeny of mutant mothers is a severe reduction in postembryonic germ-line proliferation.

To better understand the role of mes-3 in germ-line development, we have initiated cloning and molecular characterization of the gene. mes-3 maps between unc-38 and , dpy-5 ,a region spanned by a contig. We have been taking two approaches toward cloning mes-3 :defining a smaller interval which contains mes-3 and transformation rescue using YACs and cosmids.

To establish a leftward boundary, we used the polymorphism mapping technique described by H. Browning (WBG vol. 12 #2) to map the endpoint of hDf6 .a deficiency that uncovers unc-38 ,but does not uncover mes-3 or dpy-5 ,to the cosmid F14A9 .A rightward boundary for the mes-3 region was established by Bristol/Bergerac polymorphism mapping. The cosmid C30F8 detects Ava I and Hinc II polymorphisms between the two strains. Recombination mapping of these polymorphisms relative to unc-73 , mes-3 .and dpy-5 ,placed them to the right of mes-3

We have obtained transformation rescue of mes-3 with the YACs Y55F5 and Y72E2 ,and more recently with the cosmid B0231 .Using B0231 as a probe, we were able to detect polymorphic fragments (EcoR I, Hind III, and Sst I) in Southern analysis of the mutant allele bn35 .

To narrow down the mes-3 -containingregion, we are currently screening for phage that hybridize with B0231 and attempting rescue with restriction fragments of B0231 .

Literature Cited:

Capowski et. al. Genetics 129: 1061-1072

H. Browning (WBG vol. 12 #2)

Figure 1