Worm Breeder's Gazette 10(1): 78

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.

Rearrangements of Linkage Group I

K.S. McKim, A.M. Howell and A.M. Rose

Our genetic analysis of LG I requires rearrangement breakpoints to 
accurately map a large number of mutations.  We have been analyzing 
gamma radiation induced lethal mutations balanced by sDp2 and szT1(I:X)
for deficiencies.  So far only one deficiency (hDf6) has been found.  
hDf6 maps entirely within sDf4 and was isolated with szT1.  We have 
found hDf6/hDf6/sDP2 worms are adult steriles.  Three explanations 
that have occurred to us are:  1) the amount of gene product produced 
by the wild type alleles on sDp2 is not equal to the amount produced 
by the allele on the normal homologue,  2) sDp2 has a sterile mutation 
in the region deleted by hDf6, or  3) duplication of other loci 
results in sterility in combination with hDf6.  The last possibility 
is not likely considering hDf6/hDf6/szT1(X) worms are viable.  sT1(X) 
is a duplication of the left half of LG I (unc-13 to the bli-3 end) 
and the left end of LG X (from the lon-2 region to the unc-1 end).
A second approach to isolating LG I rearrangements has been to 
shorten sDp2.  dpy-5 dpy-5 
sDp2 hermaphrodites are phenotypically wild type (
sDp2 carries the wild type alleles of dpy-5 and unc-11) and segregate 
only 'Wt' and DpyUnc progeny.  There is no recombination between sDp2 
and the normal homologues.  From 16000 chromosomes treated with 1500 
rads, 1 Dpy and 5 Unc F1 progeny were recovered.  In a smaller 
experiment where 8000 chromosomes were treated with 3000 rads, 4 Dpy 
and 4 Unc F1 progeny were recovered.  These are currently being 
characterized.  Some events which we expected to recover in addition 
to shortened duplications are unlinked suppressors and point mutations 
or deletions within the duplication.  At present, 4 of 5 analyzed have 
been found to be shortened derivatives of sDP2.In addition a new 
translocation between LG I and LG V (hT1) has been isolated.  hT1(I;V) 
suppresses recombination from unc-42 to the left end of LG V (like eT1)
and from unc-13 to the left end of LG I (like szT1).