Worm Breeder's Gazette 8(2): 38
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.
I have been using two strategies to clone the lin-12 locus. The first strategy has been to 'walk' from eP7, a restriction fragment length polymorphism (see map and last Newsletter). To date, I have walked some 100 kb in John Sulston's cosmid library (with the invaluable assistance of John Sulston and Alan Coulson), but I have not yet oriented these clones with respect to the genetic map. The second strategy has been to look for lin-12 null mutations ['lin-12(0)'] in a Bergerac genetic background, with the hope (based on the suggestive genetic phenomenology described by Scott Emmons and coworkers and Don Moerman) that Tc1 transposition would be responsible for some of these mutations. To facilitate the isolation of lin-12(0) alleles, I constructed a strain that was predominantly Bergerac but containing the lin-12(n137) mutation: n137/n137 hermaphrodites are egg-laying defective, but some n137/lin-12(0) hermaphrodites lay eggs, which are easy to spot. I isolated six revertants in the initial search; three from animals grown at 20 C and three from animals treated at 27 C for 18 hours then grown at 20 C. (The frequency seems to be lower than that seen with EMS, but higher than the spontaneous Bristol rate). To see if any of these lin-12(0) mutants were associated with a Tc1 transposition event, I placed them in a Bristol background (to eliminate most of the Tc1's from Bergerac) by a backcross regime that included a three-factor cross. DNA's from the backcrossed strains were digested with several restriction enzymes and Southern blots were probed with Tc1. One revertant, lin-12(n137e1979), obtained after heat-shock treatment, had a novel 2.9 kb band in the HindIII digest; further mapping showed that this band is tightly linked to lin-12.