Worm Breeder's Gazette 10(2): 153

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.

g-ray Mutagenesis - A Few Observations

Monica Driscoll, Elke Bergholz and Marty Chalfie

We have been using gamma-irradiation to induce mutations in the mec 
genes and ben-1 and thought we might share some of our observations.  
The first is that all irradiators are not alike.  Although a number of 
people have cobalt sources, at Columbia we have a cesium source.  
Cesium is a weaker energy source, and we find that standard 
irradiation protocols are not effective.  A dose of 4050 rads is 
needed to reduce brood size by 50%, and a dose of 8100 rads reduces it 
by 80%.
In a screen for touch mutants, irradiating with 4050 rads, we 
identified 27 mutations from 180,000 mutagenized haploid genomes.  
These mutations mapped to the majority of the mec genes, and genes 
that were frequent targets with EMS also appeared to be frequent 
targets of gamma-
We identified five ben-1 mutations by screening F2 progeny for 
benomyl resistance following irradiation with 8100 rads.  The DNA from 
strains with these mutations has been examined by Southern blot 
analysis using ben-1  -tubulin DNA as a probe.  Four harbor large 
deletions in the gene; the fifth strain seems to have a smaller 
deletion.  Since this approach appears to be useful in generating 
substantial deletions within non-essential genes it should be useful 
in determining where genes are within contigs.