title: A Role of Corazonin Receptor in Larval-Pupal Transition and Pupariation in the Oriental Fruit FlyBactrocera dorsalis(Hendel) (Diptera: Tephritidae).
abstract: Corazonin (Crz) is a neuropeptide hormone, but also a neuropeptide modulator that is internally released within the CNS, and it has a widespread distribution in insects with diverse physiological functions. Here, we identified and cloned the cDNAs ofBactrocera dorsalisthat encode Crz and its receptor CrzR. MatureBdCrzhas 11 residues with a unique Ser11substitution (instead of the typical Asn) and a His in the evolutionary variable position 7. TheBdCrzRcDNA encodes a putative protein of 608 amino acids with 7 putative transmembrane domains, typical for the structure of G-protein-coupled receptors. When expressed in Chinese hamster ovary (CHO) cells, theBdCrzRexhibited a high sensitivity and selectivity for Crz (EC50≈ 52.5 nM). With qPCR, the developmental stage and tissue-specific expression profiles inB. dorsalisdemonstrated that bothBdCrzandBdCrzRwere highly expressed in the larval stage, andBdCrzRpeaked in 2-day-old 3rd-instar larvae, suggesting that theBdCrzRmay play an important role in the larval-pupal transition behavior. Immunochemical localization confirmed the production of Crz in the central nervous system (CNS), specifically by a group of three neurons in the dorso-lateral protocerebrum and eight pairs of lateral neurons in the ventral nerve cord. qPCR analysis located theBdCrzRin both the CNS and epitracheal gland, containing the Inka cells. Importantly, dsRNA-BdCrzR-mediated gene-silencing caused a delay in larval-pupal transition and pupariation, and this phenomenon agreed with a delayed expression of tyrosine hydroxylase and dopa-decarboxylase genes. We speculate that CrzR-silencing blocked dopamine synthesis, resulting in the inhibition of pupariation and cuticular melanization. Finally, injection of Crz in head-ligated larvae could rescue the effects. These findings provide a new insight into the roles of Crz signaling pathway components inB. dorsalisand support an important role of CrzR in larval-pupal transition and pupariation behavior.
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University Chongqing, China.
authors.forename: Qiu-Li
authors.initials: QL
authors.lastname: Hou
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University Chongqing, China.
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University Chongqing, China.
authors.forename: Shun-Hua
authors.initials: SH
authors.lastname: Gui
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University Chongqing, China.
authors.forename: Er-Hu
authors.initials: EH
authors.lastname: Chen
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University Chongqing, China.
authors.forename: Dan-Dan
authors.initials: DD
authors.lastname: Wei
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University Chongqing, China.
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Li
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University Chongqing, China.
authors.forename: Jin-Jun
authors.initials: JJ
authors.lastname: Wang
authors.affiliation: Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest UniversityChongqing, China; Department of Crop Protection, Ghent UniversityGhent, Belgium.
authors.forename: Guy
authors.initials: G
authors.lastname: Smagghe
keywords: Bactrocera dorsalis; RNA interference; corazonin; corazonin receptor; expression pattern; larval-pupal transition; neuropeptide; pupariation behavior