A reexamination of the leucine tRNAs and the leucyl-tRNA synthetase in developing Tenebrio molitor

The translational control mechanism previously proposed for the synthesis of adult cuticular proteins in Tenebrio molitor is dependent upon the appearance of a major, novel leucine tRNA and a change in leucyl-tRNA synthetase activity just prior to adult emergence. The properties of the leucyl-tRNA synthetase extracted from pupae were reexamined. Under optimal aminoacylation conditions, no new leucine isoaccepting tRNAs were observed during development. However, under suboptimal conditions, a differential charging of the leucine tRNA species was noted. The chromatographic profiles of leucyl-tRNAs aminoacylated in vivo in both early and late pupae were found to be the same and were identical to the profiles obtained by charging tRNAs in vitro. Previous evidence for a translational control system operating in Tenebrio is discussed in relation to these results.