Worm Breeder's Gazette 10(1): 15
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.
We are attempting to clone age-1 by the congenic strategy of Ruvkun, et al. The age-1 gene confers a phenotype of long life span and low hermaphrodite self fertility (Hsf). The gene cosegregates with fem-15 and thus maps to a region of linkage group II between dpy-10 and unc-4. Deficiency mapping using the Hsf phenotype supports this map location and we are continuing our mapping of the long-life phenotype itself to confirm these locations. Nine congenic strains were constructed by crossing age-1 to Bergerac BO, then backcrossing to the mutant strain nine more times. The object was to incorporate the wild- type Bergerac DNA around age-1 into the Bristol background of the mutant strain. In order to construct these lines, we took advantage of the low fertility of age-1 males and the fact that the Ts and Hsf phenotypes are closely associated with age-1, since constructing these lines by assaying life span at each generation would take about three years. When age-1 males are crossed to Bergerac BO hermaphrodites (the first generation) the progeny males are 100% heterozygous for age-1 and therefore wild type for the male sterility phenotype. When these F1 males are successively backcrossed to sterilized age-1 hermaphrodites, the 50% age-1 males expected in each generation cross poorly compared to the heterozygotes, yielding more progeny of the desired genotype from the backcross than of the undesirable genotype. After the backcrosses, the lines were selfed for five generations at 20 C. Strains were checked at the fifth and tenth backcross for the Ts and Hsf phenotypes, and again after homozygosis, when 50% were Ts+ ( as expected). The final strains were checked for life span and all of the nine that were wild type for Ts and Hsf also demonstrated a wild type life span. We have grown up these congenic strains in mass liquid culture by a modification of the method of Sulston and Brenner, and isolated DNA. Southern blots probed with Tc1 show the appearance of several new Tc1 bands in the congenic lines. We are continuing our molecular analysis of these lines using other restriction enzymes, and are currently constructing recombinants in the dpy-10 o define which Tc1 elements map most closely to the right and the left of age-1.