Worm Breeder's Gazette 14(1): 57 (October 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.


Margaret Sedensky, Phil Morgan

Departments of Anesthesiology and Genetics, Case Western Reserve University, Cleveland, OH, 44106

      Since around the turn of the century, we have been interested in the
gene unc-79.  Mutations in this gene alter sensitivity in C. elegans to
some volatile anesthetics but not to others, which has led to the
postulation of multiple sites of action for these drugs.  unc-79 would
then occupy an upstream position in a pathway controlling sensitivity to
volatile anesthetics.
      unc-79 maps near the middle of chromosome III, between unc-93 and
dpy-17.  By mapping relative to polymorphisms we narrowed the region down
to the cosmid C24F11 on the left and the gene mab-21 on the right.  (King
Chow had earlier shown that unc-79 was to the left of mab-21).  Therefore
we started to try to rescue the phenotype with cosmids in the region.
Several  combinations of cosmids on the left end of this region rescued
the phenotype (won't bore you with details), and the common cosmid between
them was C03E7.  So guess what....we tried C03E7 alone and it rescued the
unc-79 phenotype.
      At the same time we collected spontaneous unc-79 animals from a
RW7097 background using a precomplimentation screen.  We identified 6 new
alleles of unc-79 .  After 10 outcrosses 5 of these spontaneous alleles
have a transposon in C03E7.  One has no identifiable insertion.  The
flanking cosmids show no insertions.  All of the insertions map to a 6.5
kb EcoR1 fragment on C03E7.  Subcloning and sequencing this fragment show
it to contain exclusively, and almost all of, the predicted gene, E03A3.6,
identified by the sequencing project.  This is a good news, bad news
answer since this gene shows no overwhelming homologies to anything really
      One interesting aside to all this, is that the first predicted
intron in this gene has a bunch of telomeric sequences in it and there is
at least one such sequence in the region before the first exon.  Could
these represent the internal sequences for meiotic lining up postulated by
Ann Rose?  Using these regions as a query sequence, multiple other cosmids
with similar regions turn up in a homology search.  They may also cause
the difficulty we had obtaining a subclone of this region of the gene.
      Obviously, we have to prove this is the unc-79 gene.  The usual
cDNAs, polyA blots and rescue with small pieces containing only E03A3.6
are worked on.  Things are looking up, though.