CODON USAGE PATTERNS AMONG GENES FOR LEPIDOPTERAN HEMOLYMPH-PROTEINS

Patterns in codon usage were examined for the coding regions of the 23 known lepidopteran hemolymph proteins. Coding triplets are GC rich at the third position and a significant linear relationship between GC c ontent of silent and nonsilent (replacement) sites was demonstrated. I ntron GC content was significantly lower than in coding regions and no relationship between intron GC content and the same at silent and non silent sites was found. Though hemolymph proteins are all produced by the same tissue-fat body-significantly less bias was observed when all moth sequences were pooled than when sequences of the two major speci es were analyzed separately, as predicted by the genome hypothesis. In cases where no statistically significant bias was observed, polar or acidic/basic amino acids were almost exclusively involved. Calculation of codon adaptation indices (CAI) was of limited value in quantifying the degree of codon bias and probably reflects the complexity of mult icellular-organism life cycles and the changing patterns of gene expre ssion over different developmental stages.