Worm Breeder's Gazette 14(2): 29 (February 1, 1996)

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.

Deletions Targeted on unc-101

Jeong-Yau Ho, Mark Edgley, Ann Rose

Department of Medical Genetics University of British Columbia 6174 University Boulevard Vancouver, BC V6T 1Z3 Canada

Preliminary genetic mapping of a set of EMS-induced lethal mutations
balanced by the inversion hIn1 on LG I placed them in the relatively
marker-poor region around unc-101.  More precise mapping was hampered by
the lack of overlapping deficiencies, so we set out to generate new
deficiencies using unc- 101 as a target in F1 noncomplementation

In this approach, two parental strains were constructed in which the
hIn1 balancer chromosome was marked with both unc-101 and unc-54
mutations, and the balanced chromosome was marked either with unc-75 or
unc-59.  These two strains (KR2730, unc-75/hIn1[unc-101 unc-54], and
KR2731, unc-59/hIn1[unc- 101 unc-54]) were irradiated with UV light and
the F1 progeny were screened for the presence of Unc-101 non-Unc-54
animals.  We hoped that these would carry deficiencies of unc-101.

Three unc-101 animals that gave about 25% unhatched eggs were isolated
from among the progeny of approximately 97,000 screened F1's.  The
unhatched eggs, putative deficiency homozygotes, were subjected to PCR
analysis using primers to sequence-tagged sites (STS) on the unc-101
contig.  The oligonucleotide sequences were derived from the ends of
YACs or cosmids, and were kindly provided by the St. Louis and Cambridge
sequencing groups.  The molecular extents of the three new deficiencies,
hDf15, hDf16 and hDf17, are shown in the figure.  A fourth deficiency
(sy216) that deletes unc-101 and some surrounding DNA was kindly
provided by the Sternberg lab.  The Unc-101 phenotype of hDf16 and
hDf17, which do not delete any of the existing STS fragments in the
unc-101 gene, can probably be attributed to deletion of other exons or
of functional elements such as the promoter.

The four deficiencies were then used to map EMS-induced lethals.  As
shown in the figure, let-45, let-46, let-47 and let-48 complemented
sy216 but failed to complement hDf15, differentiating the right ends of
these two deficiencies.  Five other lethals and unc-75 were mapped
between the left ends of sy216 and hDf16.  Inter se complementation so
far indicates that h1311, h1352 and h1356 are the same gene.

The targeting approach for generating deficiencies in a specific region
worked well, and provided us with previously unavailable tools for
genetic dissection.  These tools will facilitate further alignment of
the genetic and molecular maps in the unc-101 region, and the approach
is easily adapted for use in other regions for which suitable balancers