Expression of a Drosophila melanogaster amber suppressor tRNA(Ser) in Caenorhabditis elegans

The purpose of this study was to test a cloned amber-suppressing tRNA(Ser) gene derived from Drosophila melanogaster for its ability to produce amber suppression in the nematode Caenorhabditis elegans. To date, all characterized nonsense suppressors in C. elegans have been derived from tRNA(Trp) genes. Suppression was assayed by monitoring the reversal of a mutant tra-3 phenotype among individuals transformed with the cloned Drosophila suppressor gene. An amber allele of tra-3 results in masculinization of XX animals with accompanying sterility. Complete suppression was observed among the transformants. The presence of the heterologous transgene, in both suppressed experimental animals and controls injected with a non-suppressing wild-type Drosophila tRNA(Ser) gene, was verified by PCR amplification of DNA from single worms using primers flanking the tRNA(Ser) gene. Suppression by the heterologous transgene was comparable in quality to that produced by endogenous C. elegans suppressors, and, in frequency as well as quality, to that produced by a transgenic C. elegans tRNA(Trp)-derived suppressors. Thus, a heterologous suppressor gene will function in C. elegans, and it need not be based on tRNA(Trp).