Abstract:

Octopamine（OA）is an important biogenic amine in invertebrates. As a neurotransmitter,OA binds to its receptors and co-involves with its receptors in regulating various physiological functions of insects,such as olfactory,oviposition,motion,learning,memory and immune response. To explore the functions of octopamine receptors in Eocanthecona furcellata,and to provide a reference for studying the response mechanism of E. furcellata,a natural enemy of crop pests,to adverse stress,we obtained 2 OctβR genes based on the transcriptome sequencing results and RACE technology. After bioinformatics analysis of its sequence,we analyzed developmental patterns of 2 OctβRs and its expression variations after treated with sub-lethal dose λ-cyhalothrin and chlorpyrifos through the RT-qPCR analysis. Results showed that the open reading frame length and putative protein length of EfOctβ1R and EfOctβ2R genes from amplification were 1 245 and 1 230 bp,and they encoded 414 and 409 amino acids,respectively. They all belonged to hydrophobic protein and proteins’ sequences contained seven transmembrane domain structure and some highly reserved domain structure such as cysteine residues loci,protein kinase C,ligand binding sites and glycosylation sites. They all were typical members of the G protein-coupled receptor superfamily. The results of homology analysis demonstrated that the 2 EfOctβR genes belonged to two distinct branches,Octβ1R and Octβ2R. Two EfOctβR genes were detected at different developmental stages in the whole development cycle of E. furcellata,while the expression level of the genes varied at different developmental stages. The expression was quite high at the adult stage of E. furcellata,and the expression of EfOCTβ2R at the egg stage was higher than that at the nymphal stage,but the expression level of EfOctβ1R at the egg stage was in opposite way. After treated with sub-lethal doses of λ-cyhalothrin and chlorpyrifos,the 2 EfOctβR genes responded strongly,and both presented the increased expressions by over 12 times at 24 and 36 h after the treatment,respectively. The results of this study suggest that EfOctβRs may be involved in the stress response of E. furcellata under insecticide stress.

Key words: Eocanthecona furcellata, octopamine receptor, gene cloning, sequence analysis, stress response