Worm Breeder's Gazette 13(5): 77 (February 1, 1995)

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.

Spotting homozygous end deficiencies

Kelly Adames, Robert Johnsen and Ann Rose.

Department of Medical Genetics, University of British Columbia,B.C.,V6T

eT1 is a reciprocal translocation between the right end of chromosome III
and the left end of chromosome V. eT1 heterozygotes have a wild-type
phenotype.(Figure 1)
They segregate 16 possible genotypes; 4 wild-type eT1 heterozygotes, 1 
Dpy-18;Unc-46 homozygote, 1 Unc-36 homozygote and 10 aneuploids 
(Rosenbluth and Baillie, 1981. Genetics. 99:415-428.). We are interested 
in trying to identify and correlate the phenotypes of aneuploids with
their genotypes. There are 6 possible genotypes for the aneuploids, shown
below. Note that unlike the other  genotypes, aneuploids C and E lack a
chromosome  end; C lacks LGV left and E lacks LGIII right. (Figure 2)

In the progeny of eT1 heterozygotes, we observed arrested eggs and L1 
larvae. We think the eggs may be homozygous for deletions of the ends of 
the chromosomes. The eggs have a uniform 'blebby' appearance and seem to 
arrest before the comma stage. There are two classes of arrested eggs - 
"spot" and "no spot". The "spot" egg is easy to identify because within 
it is a dark spot that measures approximately 10 mm by 15 mm. This spot 
can be in the middle or at one end of the egg. The other class of egg is 
identified by the lack of a spot. These eggs often have a slightly 
darkened region at one end. Primers for LGIII right and LGV left will be 
used in PCR experiments, to verify the genotypes of the two eggs.

Potentially, this approach, using segregation of reciprocal 
translocations, can be applied to isolate 'end' deficiencies for one  end
of each chromosome.