Worm Breeder's Gazette 8(1): 9

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.

Gamma Radiation-induced Map Expansion in C. elegans

J.S. Kim, A.M. Rose

The genetic map of C.  elegans shows clearly defined clusters of 
genes on the autosomes.  Brenner (1974) suggested the possibility that 
these clusters might be produced by a lower frequency of recombination 
in a defined region of a chromosome.  In D.  melanogaster, treatment 
with ionizing radiation (and other factors) results in large increases 
in recombination frequency across centromeric regions primarily.  
These increases in recombination frequency have been termed 'radiation 
induced map expansion'.  We have investigated the occurrence of 
radiation induced map expansion in C.  elegans.  Previously, some of 
the factors that alter recombination frequency in the dpy-5 
of linkage group I were examined (
temperature, parental age, and rec-1, for example).  Currently, we 
have investigated the effect of gamma radiation on recombination in 
this interval.  We found that treatment with gamma increases: 
recombination frequency two to three-fold, nondisjunction eight-fold, 
and F1 sterility from 0 to 14%.  We are further investigating the 
sensitivity of different meiotic stages.
The existence of 'map expansion' in the dpy-5 
which corresponds to the region of the 
cluster on linkage group I), implies that recombination in this region 
can occur more frequently than it does in control strains.  One 
possibility is that recombination frequency in this region is 
'normally' reduced (as proposed by Brenner).  We are investigating 
this phenomena for other regions of linkage group I.