Worm Breeder's Gazette 9(2): 100
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.
MK546 has the genotype age-1(hx546) 6) II unc-31( e169) IV; age-1 is a mutation conferring extended life and a 70% reduction in brood size. It is tightly linked to fer-15. By this criterion the age-1 locus has been mapped to linkage group II. MK546 is male sterile, but reisolates from crosses to N2 are male fertile, albeit at a reduced level. An age-1 reisolate, TJ401, carries fer-15 and is Brd (has about 30% of the progeny of N2) as was true for all other long-lived reisolates of age-1. We have performed a series of three-factor crosses both to precisely localize the position of age-1 and to separate by recombination the Brd and Age phenotypes, if possible. A three-factor cross using dpy-10(e128) 44) II was performed by crossing TJ401 males with the double mutant and cloning Unc non-Dpy and Dpy non-Unc F3 progeny; subsequently, assays for Brd, Age, and Fer were performed on their progeny. Among the recombinants were 8 Fer 10 non-Fer Dpy non- Unc, and 1 recombinant non-Fer Unc non-Dpy. The recombinants were scored for Brd by assaying the number of progeny produced by 3 individuals. Parents were allowed to lay on individual plates and were transferred every 2 days until sterile. The progeny were counted 1 day after the removal of the parents. All Fer recombinants were Brd, and all non-Fer recombinants were non-Brd. This places the fer-15 and brd loci 0.5 to 1.5 map units to the right of dpy-10. Scoring of Age proved difficult because unc-52 significantly reduces life-span. A second three-factor cross using dpy-10(e128) 0) II allows more precise mapping. 58 recombinants were analyzed: 25 were Dpy non-Unc and 33 Unc non-Dpy. Brd was scored as before and again showed complete linkage between fer-15 and brd. The following data position brd and fer-15 0.6 map units to the right of dpy-10.[See Figure 1] The dpy-10 and unc-4 loci affect life-span. Since age-1 is recessive with regard to life-span, we have been trying to score life- span on dpy-10 or unc-4 F1 heterozygote males obtained by backcrossing recombinants to TJ401. Controls consisted of N2 males, F1 males of unc-4 by TJ401 males, F1 males of dpy-10 by TJ401 males, and TJ401 males. Our data currently suggests that the age-1 gene may be separable from the brd and fer-15 genes by as much as 0.5 map units, but we remain uncertain of the interpretations of the age-1 genotype derived from the analysis of heterozygotes. A third three-factor cross is underway using a triple heterozygote ( dpy-10 unc-4) male, test-crossed to dpy-10 odites. Wild-type recombinants in the male can be identified and subsequently scored for Age and Brd without the interference of the dpy-10 and unc-4 mutant loci which make difficult the reliable scoring of the life-span phenotype of the age-1 locus.