Worm Breeder's Gazette 7(1): 83

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.

Phenotypic Suppression of TRA-3 by Microinjection of SUP-7 tRNA

J. Kimble, J. Hodgkin, J. Smith

tra-3 mutants have a maternal defect that causes XX selfprogeny to 
develop as pseudomales.  Two alleles have been identified.  One is 
suppressible by sup-5 and sup-7, and one is not.  Recently, sup-5 and 
sup-7 tRNAs have been shown to have amber suppressor activity (
Waterston and Gesteland, personal communication).  We have therefore 
extracted sup-7 tRNA (a crude eluate including all tRNA plus 5S RNA) 
and attempted to rescue the maternal amber tra-3 mutant.  Suppressor 
tRNA was microinjected into the distal arm of a tra-3 homozygous 
hermaphrodite (derived from a heterozygous mother).  60% of the 
parents injected ( 6 out of 10 animals) gave rise to hermaphrodite 
progeny, albeit only 3 hermaphrodites per parent.  The average brood 
size of the injected animals was 100 and most progeny were pseudomales 
confirming the genotype of the mother.  The hermaphrodite progeny were 
shown to be homozygous tra-3 animals because all were fertile and 
produced only pseudomales.
Control experiments show that the background of hermaphrodites 
produced by tra-3 homozygotes is zero.  Wild type tRNA was injected 
into 10 amber tra-3 animals, the average brood size was 100, but no 
hermaphrodite progeny were made.  Sup-7 tRNA was injected into 10 non-
amber tra-3 animals, the average brood size was about 100, but again 
no hermaphrodites were made.  4000 progeny have been screened from 
uninjected animals, and none was hermaphrodite.