Worm Breeder's Gazette 11(4): 55

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.

lin-34/let-60: Dominant Muv Mutations Increase Wild-Type Gene Activity, Dominant Vul Mutations Antagonize Wild-Type Gene Activity

Greg Beitel, Scott Clark and Bob Horvitz

Figure 1

lin-34 mutations can cause a dominant Multivulva (Muv) phenotype, 
while let-60 mutations can cause dominant Vulvaless (Vul), recessive 
lethal or recessive Vul/lethal phenotypes.  lin-34 and let-60 are 
likely to be the same gene because they map very close together and 
the tightly linked lin-34(n1046) suppressor n1981 is a recessive 
lethal mutation that fails to complement let-60 mutations.  
Preliminary molecular data are consistent with this interpretation (
Min Han and Paul Sternberg, personal communication; also our 
unpublished observations).  We investigated the nature of the dominant 
Muv and dominant Vul alleles using a new duplication of chromosome IV, 
nDp5.  Isolated by Saechin Kim, nDp5 appears to be a free duplication 
that spans lin-34/let-60 and extends from at least unc-44 to unc-26, 
covered.  Using this duplication 
and a deficiency that spans the lin-34/let-60 region, we constructed 
strains containing varying doses of the wild-type and mutant alleles.  
As seen in the table below, the dominant Muv mutations n1046 and n1700 
show an increasingly severe phenotype with increasing copies of the 
wild-type gene.  This result suggests that these mutations cause an 
increase in a wild-type-like gene activity and are therefore 
hypermorphic mutations.  The dominant Vul mutations n1631 and n2031 
seem to antagonize the wild-type gene activity and thus are 
antimorphic mutations.  However, the dominant Vul mutations are not 
able to antagonize the activity of the dominant Muv mutations, since 
dominant Muv/dominant Vul heterozygotes have the same phenotype as 
dominant Muv/+ heterozygotes.
Since nDp5 appears to be a free duplication that is lost at a fairly 
high rate during meiosis, we will attempt to do mosaic analysis of the 
lin-34/let-60 locus using nDp5.[See Figure 1]

Figure 1