Worm Breeder's Gazette 9(3): 31

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.

Tc1-Induced Lethal Mutations on LGIV (Right) and LGV (Left)

D.V. Clark, K. McKim and D.L. Baillie

As part of our ongoing genetic analysis into the organization of 
essential genes on LGIV (right) and LGV (left), we have conducted a 
screen for Tc1-induced lethal mutations in these regions. A strain was 
constructed with the mutator activity on LGI (derived from RW7037, 
Moerman and Waterston, 1984, Genetics, 108:859-877) and the balancer, 
nT1 (Ferguson and Horvitz, 1985, Genetics, 110:170-72), which 
suppresses recombination on LGIV from almost unc-17 to dpy-4 and on 
LGV from unc-60 to at least sma-1 [approximately 40 m.u. overall). The 
genotype of the strain used for our screen was mut-4/mut-4 (I?;unc-
We screened 3503 F1 'chromosomes' and 35 lethal mutations were 
recovered: a rate of 1%. In order to reduce the likelihood of 
reversion or further Tc1-induced mutations, each strain was outcrossed 
and the 'mutator' chromosome was segregated out. This was done by 
using a dpy-5 marked chromosome [see Mori et al., WBG 9(1), p. 25].
So far, 7 lethals have mapped to LGIV and 23 to LGV. Comparison with 
EMS mutagenesis data [4.4% lethals on LGIV, 3.4% lethals on LGV; see 
WBG 9(2), p. 82] indicates that there is probably a mutational hotspot 
for Tc1 on LGV. The deficiency mapping and inter se complementation 
tests of these lethals, now in progress, will indicate if this is the 
Tc1-tagged essential genes will be extremely useful for 
characterization and positioning of cloned sequences with respect to 
the genetic maps of LGIV(right) and LGV(left).