Résumé
Synonymous mutations were thought to be evolutionarily neutral as they do not alter the amino acid sequence of proteins. However, these mutations can alter translation efficiency by affecting mRNA folding and splicing. Thus, the accumulation of these mutations and the selective pressure on them can lead to codon usage bias, a preferred use of one type of codon per amino acid. This bias is related to GC content, a higher or lower GC content in the genome can affect the regulation of gene expression via the methylation mechanism. Since this bias occurred in mRNA in Lysiphlebus fabarum, we focused on transcriptomic sequences of insects to see if this phenomenon is shared between taxa. Moreover, GC content shifts during development in this species, so we investigated the GC content shift in differentially expressed genes between larvae and adults in Diptera, Hymenoptera and Lepidoptera species.In seven species, RNA sequences obtained from databases were analyzed and compared between larvae, adult males and females for GC content distribution. First results showed a higher GC content in larval transcripts compared to adults. An analysis of GC content in differentially expressed genes among gene families of orthologs with representatives in almost all species examined showed that these genes tend to have higher GC content in Hymenoptera and Diptera. Searching for an explanation for poor-GC genomes, a model based on whole genome GC content in insects showed an association between parasitic behavior and a reduction in mean GC content in Diptera and Hymenoptera.
This study allows us to identify shifts in GC content within species during development, despite a shared genome. The underlying adaptations behind this bias need to be investigated with the provided candidate genes.
la date de réponse | 2024 |
---|---|
langue originale | Anglais |
L'institution diplômante |
|
Superviseur | Alice Dennis (Promoteur) |