Worm Breeder's Gazette 9(3): 30

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mut-2 and Spontaneous mec Mutations

P. Brickman, P. Josephson, S. Shaham, C. Savage, M. Penn, C. Ferguson and M. Chalfie

Figure 1

We have continued to isolate and characterize mec mutants in TR679 
[mut- 2(r459)]. Our progress to date 
{Figure 1}
Thus, nine of the 16 genes for which we've obtained touch 
insensitive mutants are represented in this set. (In addition, we have 
isolated two unc-55 mutants and several unc-31 mutants in these TR679 
screens.) The outcrossing and analysis of these mutations is in 
various degrees of completion. We have used these mutations to isolate 
the mec-3 gene (WBG 9 #1 p. 31) and the mec-14 gene (see this issue). 
In addition, a single Tc1-containing fragment cosegregates with the 
one mec-2 mutation so far studied.
As indicated in the table, we have obtained spontaneous revertants 
in a number of the TR679-derived mec strains. Four of these were found 
by screening the original mec isolates before outcrossing. This was 
usually difficult as the strains were often unhealthy and had low 
brood sizes. Recently, however, we have taken advantage of the mut-2 
mutator activity mapped near unc-13 by Mike Finney. By eliminating a 
unc-13(e51) chromosome, we made mut-2:mec doubles using outcrossed 
strains with spontaneous mutations in mec-2, 
lting strains were quite healthy 
and had reasonable brood sizes. All three strains have reverted to 
wild type will relative ease (i.e. a single afternoon's worth of 
screening). One advantage of this method is that Mec and nonMec 
siblings are often healthy enough to grow up to generate DNA for 

Figure 1