RNAi-Mediated Functional Analysis of Bursicon Genes Related to Adult Cuticle Formation and Tanning in the Honeybee, Apis mellifera

Author(s)

Costa, Claudineia Pereira ; Elias-Neto, Moyses ; Falcon, Tiago ; Dallacqua, Rodrigo Pires ; Martins, Juliana Ramos ; Gentile Bitondi, Marcia Maria

• Document type: Journal article
• Source: PLoS One; v. 11, n. 12 DEC 1 2016.
• Web of Science Citations: 2

Abstract

Bursicon is a heterodimeric neurohormone that acts through a G protein-coupled receptor named rickets (rk), thus inducing an increase in cAMP and the activation of tyrosine hydroxylase, the rate-limiting enzyme in the cuticular tanning pathway. In insects, the role of bursicon in the post-ecdysial tanning of the adult cuticle and wing expansion is well characterized. Here we investigated the roles of the genes encoding the bursicon subunits during the adult cuticle development in the honeybee, Apis mellifera. RNAi-mediated knockdown of AmBurs a and AmBurs beta bursicon genes prevented the complete formation and tanning (melanization/sclerotization) of the adult cuticle. A thinner, much less tanned cuticle was produced, and ecdysis toward adult stage was impaired. Consistent with these results, the knockdown of bursicon transcripts also interfered in the expression of genes encoding its receptor, AmRk, structural cuticular proteins, and enzymes in the melanization/sclerotization pathway, thus evidencing roles for bursicon in adult cuticle formation and tanning. Moreover, the expression of AmBurs a, AmBurs beta and AmRk is contingent on the declining ecdysteroid titer that triggers the onset of adult cuticle synthesis and deposition. The search for transcripts of AmBurs a, AmBurs beta and candidate targets in RNA-seq libraries prepared with brains and integuments strengthened our data on transcript quantification through RT-qPCR. Together, our results support our premise that bursicon has roles in adult cuticle formation and tanning, and are in agreement with other recent studies pointing for roles during the pharate-adult stage, in addition to the classical post-ecdysial ones. (AU)

• FAPESP's process: 10/16380-9 - Molecular genetics and hormonal regulation of exoskeleton differentiation in an insect model, Apis mellifera
• Grantee: Marcia Maria Gentile Bitondi
• Support Opportunities: Regular Research Grants
• FAPESP's process: 14/13136-0 - RNA-seq for characterization of the genes involved in the construction and differentiation of the insect exoskeleton using bees as a model
• Grantee: Marcia Maria Gentile Bitondi
• Support Opportunities: Regular Research Grants
• FAPESP's process: 09/15635-6 - Characterization of genes encoding bursicona and research function of the product as possible heterodimeric regulator of differentiation of the exoskeleton of adult Apis mellifera
• Grantee: Claudinéia Pereira Costa
• Support Opportunities: Scholarships in Brazil - Scientific Initiation