The ribosomal proteins of Drosophila melanogaster. V. Analysis by two-dimensional gel electrophoresis of the ribosomal proteins of the temperature-sensitive lethal allele of suppressor of forked, l(1) su(f)ts67g: a putative ribosomal protein mutant.

The possibility that the ribosomes of a temperature-sensitive lethal allele of suppressor of forked, l(1)su(f)ts67g, contain a mutated protein was studied by two-dimensional gel electrophoresis. The results from these analyses revealed no differences in the ribosomal proteins between the mutant and the wild-type strain Ks. It was found, however, that the transition from larval to adult ribosomal protein complement, which occurs mainly during the third instar in Käs, takes place during puparium formation in the mutant at 25 degrees C while it appears to be fatally delayed at 30 degrees C. Thus mutant larvae shifted up to 30 degrees C at 70 hours after oviposition failed to pupate, but reached the third instar and showed an adult ribosomal protein pattern after 4 days. Also, the ribosome content in these larvae was found to be significantly lower compared with late third instar larvae. It was furthermore found that larvae collected within 50 hours of transfer back to 25 degrees C, after a 5 day, 30 degrees C treatment, showed a reversion to a ribosomal protein pattern identical with that of Käs late third instar larvae. The results suggest that the biosynthesis of imaginal ribosomes in l(1)su(f)ts67g is seriously impaired at 30 degrees C and less so at 25 degrees C. Further studies are necessary, however, in order to understand the exact nature of this mutant, which may turn out to be a useful tool in studies on the biosynthesis of ribosomes in D. melanogaster.