Molecular characterization of an Apolipophorin-III gene from the Chinese oak silkworm, Antheraea pernyi (Lepidoptera: Saturniidae).

Abstract

Apolipophorin-III (ApoLp-III) acts in lipid transport, lipoprotein metabolism, and innate immunity in insects. In this study, an ApoLp-III gene of Antheraea pernyi pupae (Ap-ApoLp-III) was isolated and characterized. The full-length cDNA of Ap-ApoLp-III is 687 bp, including a 5'-untranslated region (UTR) of 40 bp, 3'-UTR of 86 bp and an open reading frame of 561 bp encoding a polypeptide of 186 amino acids that contains an Apolipophorin-III precursor domain (PF07464). The deduced Ap-apoLp-III protein sequence has 68, 59, and 23% identity with its orthologs of Manduca sexta, Bombyx mori, and Aedes aegypti, respectively. Phylogenetic analysis showed that the Ap-apoLp-III was close to that of Bombycoidea. qPCR analysis revealed that Ap-ApoLp-III expressed during the four developmental stages and in integument, fat body, and ovaries. After six types of microorganism infections, expression levels of the Ap-ApoLp-III gene were upregulated significantly at different time points compared with control. RNA interference (RNAi) of Ap-ApoLp-III showed that the expression of Ap-ApoLp-III was significantly downregulated using qPCR after injection of E. coli. We infer that the Ap-ApoLp-III gene acts in the innate immunity of A. pernyi.