Characterization of a β-Adrenergic-Like Octopamine Receptor in the Oriental Fruit Fly, Bactrocera dorsalis (Hendel)

Abstract

The biogenic amine octopamine plays a critical role in the regulation of many physiological processes in insects. Octopamine transmits its action through a set of specific G-protein coupled receptors (GPCRs), namely octopamine receptors. Here, we report on a β-adrenergic-like octopamine receptor gene (BdOctβR1) from the oriental fruit fly, Bactrocera dorsalis (Hendel), a destructive agricultural pest that occurs in North America and the Asia-Pacific region. As indicated by RT-qPCR, BdOctβR1 was highly expressed in the central nervous system (CNS) and Malpighian tubules (MT) in the adult flies, suggesting it may undertake important roles in neural signaling in the CNS as well as physiological functions in the MT of this fly. Furthermore, its ligand specificities were tested in a heterologous expression system where BdOctβR1 was expressed in HEK-293 cells. Based on cyclic AMP response assays, we found that BdOctβR1 could be activated by octopamine in a concentration-dependent manner, confirming that this receptor was functional, while tyramine and dopamine had much less potency than octopamine. Naphazoline possessed the highest agonistic activity among the tested agonists. In antagonistic assays, mianserin had the strongest activity and was followed by phentolamine and chlorpromazine. Furthermore, when the flies were kept under starvation, there was a corresponding increase in the transcript level of BdOctβR1, while high or low temperature stress could not induce significant expression changes. The above results suggest that BdOctβR1 may be involved in the regulation of feeding processes in Bactrocera dorsalis and may provide new potential insecticide leads targeting octopamine receptors.

Phenyl imidazolidin‐2‐ones antagonize a β‐adrenergic‐like octopamine receptor in diamondback moth (Plutella xylostella)

“…At present, OA2B1 receptor genes have been cloned in insects such as Apis mellifera, 43 Drosophila melanogaster 44 and Bactrocera dorsalis. 18 These studies further evaluated the gene expression patterns and pharmacological features of the OA2B1 gene in the individual insect species. However, OA2B1 from P. xylostella has not been cloned.…”

“…showed the highest expression in 3-day-old adults. 18 The tissuespecific expressions of the OA2B1 genes of several Lepidopterans, such as Trichoplusia ni, Pseudaletia unipuncta and Pieris rapae, have been evaluated using RT-qPCR. 45 Earlier studies have shown that the expression of OA2B1 genes of these species is higher in the Malpighian tubule but lower in the nervous system and oviduct.…”

“…In addition, a typical OAR motif (F × × × W × P) was identified, followed by two phenylalanine residues on TM6, which act as biogenic amines to facilitate ligand binding. 18 Twenty-one OAR and TAR amino acid sequences were downloaded from GenBank, and MEGA7 was further applied for multiple sequence alignment. TM1-TM7 sequences were used to construct the neighbor-joining phylogenetic tree of OARs and TARs.…”

“…The three classes are OA2B1, OA2B2 and OA2B3 receptors, also called Oct⊎R1, Oct⊎R2, and Oct⊎R3. 17,18 Among the three ⊎-OARs, OA2B1 receptors mediate various life processes in insects, such as locomotion and learning. 19,20 Octopamine (OA) and tyramine (TA) are natural ligands to insect OARs; however, OA acts on OARs more actively than TA.…”

Role of Biogenic Amines in Oviposition by the Diamondback Moth, Plutella xylostella L

“…As the efficiency of RNA interference in Lepidoptera is low, different amine receptor antagonists were used in this experiment to corroborate the roles of amines in mating-induced oviposition and to identify the specific receptors involved in this process. Mianserin has commonly been used as a non-specific antagonist of octopamine receptors in insects (Farooqui et al, 2003;Maqueira et al, 2005;Fussnecker et al, 2006;Li et al, 2016). Phentolamine and epinastine have also been reported as specific antagonists for octopaminergic receptors in insects (Evans, 1984;Lange and Orchard, 1986;Degen and Gewecke, 1998;Roeder et al, 1998;Wu et al, 2017).…”