Worm Breeder's Gazette 8(3): 42

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.

Dominant Suppressor of fem-1 and fem-2

M.K. Barton, T. Schedl, J. Kimble

Recessive mutations in fem-1 and fem-2 cause XX animals to develop 
as spermless hermaphrodites.  Temperature sensitive mutations in these 
genes have allowed us to revert them by looking for self-fertile 
hermaphrodites at the restrictive temperature.  Specifically, the F1 
of EMS mutagenized parents homozygous for either fem-1(hc17) or fem-2(
b245) was screened for fertile worms.  In this way we have isolated 
ten dominant fem suppressors, three of b245 and seven of hc17.
Dominant suppressors of hc17 appear at a frequency of 1.5x10+E-5.  
The best characterized of these is q20.  This allele, when crossed out 
of the hc17 background, causes a masculinization of the germ line (Mgl)
of XX animals.  No oocytes but only sperm are made in an otherwise 
normal hermaphrodite gonad.  Mature sperm fill up the entire proximal 
arm of the gonad and spermatogenesis extends back into the distal arm.
The q20 allele is temperature sensitive.  Hermaphrodites homozygous 
for q20 are Mgl at 25 C but fertile at 15 C.  At 15 C, animals 
homozygous for q20 have an average brood size of 445 (n=36) indicating 
that more sperm are made even at permissive temperature.  A semi-
dominant effect is observed at 25 C; about half the q20/+ 
hermaphrodite progeny from the cross q20/+ males x unc-5 
hermaphrodites are Mgl (25 C).  Males homozygous for q20 are fertile 
at 25 C.
The map position of q20 (on chromosome IV between unc-5 and dpy-20) 
suggested that it might lie at the fem-3 locus.  Therefore, an F1 
reversion of animals, fertile animals homozygous for q20 was performed.
Revertants segregate Mgl animals, fertile animals and Fem animals.  
We have shown that one of the revertants does not complement a known 
fem-3 allele (e1996).  These results suggest that q20 is in fact at 
the fem-3 locus.  The map positions and/or phenotypes of four other 
alleles (q24, q60, q61 and q62) make it likely that they too are fem-3 
Of the remaining two hc17 suppressors, one, q21, appears to be an 
intragenic revertant.  Another q63, is not linked to chromosome IV.
Dominant suppressors of b245 also occur at a frequency of 1.5x10+E-5.
Two of these, q22 and q23, have been partially characterized.  After 
removal from the b245 background, both are temperature sensitive 
sterile with a Mgl phenotype.  Both also map to chromosome IV.  q22 
has been mapped more closely and lies between unc-24 and dpy-20, 
placing it within 0.5% of fem-3.  These suppressors are probably fem-3 
dominant alleles as well.