The molecular characteristics of two metallothioneins in Ostrinia furnacalis and expression under conditions of heavy metal stress

Abstract

• Two metallothionein genes from Ostrinia furnacalis were cloned and identified. • Cd, Cu and Zn inhibit the expression of OfMT1 of Ostrinia furnacalis . • Cd and Cu induce the expression of OfMT2 of Ostrinia furnacalis . Metallothioneins are ubiquitously-expressed metal-binding proteins. Despite their potential ecological relevance, no prior reports have identified any metallothioneins in Ostrinia furnacalis or other Lepidoptera species. A better understanding of the molecular characteristics and regulatory dynamics of metallothionein genes in O. furnacalis under heavy metal stress conditions would enable future studies of the roles played by these proteins in the context of heavy metal detoxification. Herein, we identified and characterized two metallothionein ( OfMT ) genes in O. furnacalis, including the 147 bp OfMT1 gene encoding a 48 amino acid protein containing 10 cysteine residues, and the 141 bp OfMT2 gene encoding a 46 amino acid protein containing 12 cysteine residues. The expression of OfMT2 was found to be related to Cu and Cd concentrations in a dose-dependent manner but was unaffected by Zn exposure. Overall, these results indicate that OfMT genes likely encode metal-binding proteins consistent with their potential role in the maintenance of heavy metal homeostasis.