Two chitinase 5 genes from Locusta migratoria: molecular characteristics and functional differentiation

Area of Science:

• * Genomics and Molecular Biology
• * Insect Physiology and Development

Background:

• * Chitinase 5 (Cht5) gene duplication is a known phenomenon in mosquitoes.
• * The functional and evolutionary significance of Cht5 gene duplication in other insect orders remains largely unexplored.

Purpose of the Study:

• * To identify and characterize Cht5 gene duplication in the migratory locust, Locusta migratoria.
• * To investigate the expression patterns, regulation, and functional roles of the duplicated LmCht5 genes during locust development.

Main Methods:

• * Gene identification, structural analysis, and phylogenetic analysis of Cht5 genes.
• * Quantitative real-time PCR (qRT-PCR) for gene expression analysis across tissues and developmental stages.
• * RNA interference (RNAi) to assess gene function and hormonal regulation by 20-hydroxyecdysone (20E) and ecdysone receptor (EcR).

Main Results:

• * Discovery of two Cht5 genes, LmCht5-1 and LmCht5-2, in Locusta migratoria, with LmCht5-1 possessing a chitin-binding domain and LmCht5-2 appearing to be a recent duplication.
• * Both LmCht5 genes are responsive to 20-hydroxyecdysone (20E) and show similar developmental expression patterns, peaking before molting.
• * RNAi-mediated knockdown of LmCht5-1 caused severe molting defects and lethality, while LmCht5-2 knockdown had no significant effect, indicating LmCht5-1's essential role.

Conclusions:

• * The migratory locust exhibits Cht5 gene duplication, with LmCht5-1 being orthologous to known insect Cht5 genes and LmCht5-2 being a potential new duplication.
• * Both LmCht5 genes are regulated by the molting hormone 20E, but only LmCht5-1 plays a critical, non-redundant role in locust molting and survival.