Worm Breeder's Gazette 10(3): 18

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.

Update on her-1 Transcripts

Carol Trent and W.B. Wood

Genomic DNA from the region of the her-1 locus was obtained by: (i) 
transposon-induced reversion of the dominant,gf allele her-1(n695) to 
generate the recessive lf allele her-1(ct50n695), (ii) identification 
of a Tc1 insertion, ctP3, tightly linked to the ct50 mutation, (iii) 
cloning of ctP3 and unique flanking sequences, and (iv) identifying a 
contig of cosmids (courtesy of A.  Coulson and J.  Sulston) spanning 
the ctP3 site (C.  elegans Meeting Abstracts, 1987, p.  32).  This 
contig, of >200 kb, was oriented with respect to the genetic map using 
polymorphisms between DH424 and N2 strains.
Using a cDNA mapping technique, transcribed regions in the vicinity 
of ctP3 have been identified, and one of them has been further 
characterized as follows.  Orientation and rough mapping experiments 
indicate that the ctP3 site is about 3 kb upstream from the start of 
transcription.  A 1.4-kb HindIII fragment containing almost all of the 
transcribed sequence hybridizes to two bands on gel blots of RNA from 
mixed population him-8 (XX and XO) animals: an abundant 0.9-kb and a 
less abundant 1.3-kb transcript.  Both transcripts are also present in 
gravid him-8 hermaphrodites (containing XX and XO embryos), but are 
greatly reduced or absent in RNA of mixed population or gravid N2 XX 
hermaphrodites.  Two strong her-1 (lf) alleles, ct50n695 and y10  
result in disappearance of the larger transcript, but do not appear to 
affect the smaller one; two other recessive her-1 mutations, ct22n695  
do not appear to affect either transcript.  Both transcripts are 
present in her-1(n695) XX hermaphrodites (which are variably 
masculinized), but absent from tra-1(e1099) XX animals (which are 
essentially completely masculinized).  These findings are consistent 
with earlier genetic analysis and with the Hodgkin model, which 
predicted that for wild-type sex determination, her-1 activity should 
normally be high in XO animals and low or absent in XX animals, and 
that this activity should not be required for the masculinization of 
XX animals caused by tra-1(lf) mutations.  Furthermore, our results 
strongly suggest that the sex-specific activity of her-1 is controlled 
at the level of transcription, in contrast to the post-transcriptional 
mechanisms that control autosomal sex-determining genes in Drosophilia.
Transcript mapping and sequencing of her-1 genomic and cDNA clones 
are in progress.