Worm Breeder's Gazette 5(2): 51
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.
With the elucidation of DNA repair in the nematode as our long-range goal, we have begun to isolate and characterize radiation sensitive mutants of C. elegans. Twenty-four well microtiter dishes were employed in a fashion similar to that of Hirsh and Vanderslice (1976. Develop. Biol. 49, 220) to screen 4,057 and 2,377 individual F2 progeny from EMS-mutagenized animals for UV and X-ray hypersensitivity, respectively. Seven UV and three X-ray hypersensitive mutants have been obtained. At present, all ten rad (for abnormal radiation sensitivity) mutants have been backcrossed at least once to N2; three have been assigned to linkage groups. Eggs, collected by the hypochlorite method, have been employed to quantitate UV and X-ray sensitivities. Most mutants are approximately 2 to 4 times more sensitive than N2; however, one isolate is over 30- fold more sensitive to X-rays. Cross sensitivity is common, although one UV-sensitive mutant exhibits wild-type X-ray sensitivity. Certain preexisting mutants, which might be expected to exhibit radiation hypersensitivity, were also quantitatively tested for UV and X-ray sensitivities. Included were him-1, 2, 3, 5-10, unc-86, ignificantly more sensitive than N2. The above 6,434 clones were additionally screened for the presence of him mutants. Fourteen were isolated, with thirteen backcrossed at least once to N2. All but one are recessive. In addition to continuing the above genetic analyses, we plan to: (1) develop positive selections to isolate more rad mutants; (2) test N2 and all rad mutants for their sensitivities to various DNA damaging agents; (3) determine epistatic relationships by constructing multiple rad mutants; and (4) examine the effect of various rad mutations on recombination, mutagenesis, and duplication loss. Finally, we are studying a number of interesting properties of the one dominant him mutation, including its ability to change to a lethal state at a frequency of about 0.3 per generation.