Worm Breeder's Gazette 3(1): 17
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.
Among 28,647 F1 progeny of X-irradiated N2 males, we have found 17 deficiencies of the unc-3 region, and have used these in mapping the lethals. Thirteen of these deficiencies fail to complement all mutants in the region. The map shown is based on the remaining four deficiencies and on three-point crosses involving unc-3, lethals; the positions found by recombination are consistent with the deficiency map. [See Figure 1] These fourteen essential genes are defined by twenty-three lethals; a fifteenth gene, let-5, is either to the left of unc-3 or to the right of let-2. Three of the lethals have been sent to us by other labs; one of these, e1471, provided by Andras Fodor, is the only allele of let-15. The other two alien lethals, e1470 and b246ts, provided by Andras and by Judy Kimble respectively, are alleles of let- 2. Counting these two, we have six alleles of let-2, all of which are temperature-sensitive. For five of the six, the restrictive temperature is 20 C; for the sixth, b246, it is 25 C. Complementation at 20 C is complex, with each mutant complementing at least one other; all fail to complement at 25 C. We have also looked at the epistatic interaction between the hermaphrodite specific lethal let-7 and the transformer mutants tra-1 and tra-2. Homozygotes for let-7 die at about L3, while hemizygous males live to adulthood. Since hemizygous hermaphrodites of the genotype unc-3 f1 also die as juveniles, the male survival does not appear to be due to having just one let-7 gene. We then checked if the survival was male-specific by using 2X transformer males; that is, we made tra/+; unc-3 and looked for Unc male self-progeny. They die at about the same stage as the homozygous hermaphrodites, suggesting that the interaction of let- 7 with the transformers is similar to that reported by Hodgkin and Brenner for the sex-influenced mutants dpy-21 and dpy-22. We conclude that the action of let-7 is on 2X individuals regardless of sexual phenotype, but that the critical region of the X is not the let-7 gene itself nor, in fact, any gene in the region deficient in mnDf1.