Worm Breeder's Gazette 2(2): 16

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.

A Temperature Sensitive Intersex Mutant of C. elegans

G.A. Nelson, K.K. Lew, S. Ward

A recessive temperature-sensitive mutant has been isolated which 
produces a sexually dimorphic phenotype at 25 C-hermaphrodites are 
sterile and males become intersexes.  The mutant is designated tsH17; 
gene intersex-1 (isx-1), and maps 4.8+1.0% to the right of dumpy-13 on 
chromosome IV.
At 16 C tsH17 hermaphrodites produce nearly wild-type numbers of 
progeny (250) and are morphologically normal.  Males are also 
morphologically normal, produce fertile sperm and mate properly.
At 25 C mutant hermaphrodites produce no sperm but are otherwise 
normal and make oocytes which may be fertilized by wild-type males.  
In the absence of mating, however, only a few oocytes are made (10-15 
per animal) and these are laid as endoreduplicated, unfertilized eggs.
Restrictively grown animals with a single X chromosome are 
intersexes rather than males.  These animals have normal male somatic 
structures including: bursae, diagonal muscles and anterior sensory 
nerves and exhibit a rudimentary mating behavior.  Intersex gonads are 
variable in morphology from male-like to hermaphrodite-like and 
contain oocytes or abortive gametes but usually no sperm.  Vulvas or 
abortive vulvas are present in nearly half of all intersexes.  Their 
frequency of appearance and degree of normality correlate with the 
degree of 'hermaphrodicity' of the underlying gonad in a manner 
consistent with an inductive mechanism of vulva formation.
The various phenotypes of tsH17 have not been separated by 
recombination and a revertant has been isolated which partially 
corrects all of the mutant phenes examined.  Thus the pleiotropic 
effects all appear to be due to a single lesion.
The temperature sensitive periods for the various phenes differ but 
overlap.  All precede the last moult.
Experiments are now in progress to examine the interactions between 
intersex and mutant alleles of the two transformer genes tra-1, and