Identification and characterization of an Apis cerana cerana nucleoside diphosphate kinase (AccNDPK) associated with oxidative stress

Abstract

Nucleoside diphosphate kinases (NDPKs) are widespread nucleotide-metabolizing enzymes that are involved in a variety of biological processes, including responses to oxidative stress. Although studies have been conducted on NDPKs in mammals and some plants, there is scant research on insect NDPKs, especially in honey bees. In the present study, we isolated AccNDPK from Apis cerana cerana. Sequence analysis showed that AccNDPK has high homology with many NDPKs and contains a highly conserved NDPK active site motif. Based on phylogenetic analysis, AccNDPK has a relatively recent evolutionary relationship with NDPKs in other hymenopteran insects. AccNDPK was found to be highly expressed in newly emerged honey bees and muscle tissues, and RT-qPCR analysis and bacteriostatic assays showed that the expression level of AccNDPK is affected by abnormal temperature, UV light, H₂O₂, heavy metals, and various pesticides. After AccNDPK knockdown, antioxidant-related genes, including AccCAT, AccCYP4G11, AccGSTS4, AccTpx1 and AccMsrA, were upregulated, whereas AccGSTD, AccGST1, AccHSP22.6 and AccTrx1 were downregulated. Furthermore, catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) activities were significantly increased, and the tolerance of bees to oxidative stress caused by cyhalothrin was reduced by silencing of AccNDPK. Given these findings, we speculate that AccNDPK plays an important role in the oxidative stress response of A. cerana cerana.

Keywords: Apis cerana cerana; Expression pattern; NDPK; Oxidative stress; RNAi.