Identificação e caracterização de genes e seus produtos protéicos do sistema olfatório e morfologia de antena da abelha sem ferrão Melipona scutellaris (Apidae: Meliponini)

Abstract

The main role of bees in nature is pollination of angiosperms, because of it bees are responsible for biological diversity maintenance and food production as well. Brazilian stingless bees (Meliponini) pollinate 40-90% of native trees and are found worldwide, wherein Brazil is the main representative of these bees. The Melipona scutellaris species (popularly known as the uruçu do nordeste ) is distributed geographically from Bahia to Rio Grande do Norte State, in the Zona da Mata region. The understanding of caste differentiation in Melipona scutellaris is extremely important for conservation and management of this bee. In 1950, Kerr proposed the model two genes/two-locus to explain the caste differentiation in Melipona; when well fed double heterozygous larvae develop into queens and underfed larvae or homozygous for these genes become workers, as a result of low production of Juvenile Hormone. Antennae is the main organ of bee olfactory system playing an important role in mantaining of colony social organization and in the performance of caste and sexes as well. The antennae houses a great diversity of sensilla, which are very important to bee chemical communication as receptors of compounds in the air such as pheromones, leading to typical behavioral responses of individuals, species, genera or families. The second chapter we show the results from scanning electron microscopy which demonstrates a heterogeneous distribution pattern of sensilla along the antenna. The main types of sensillum found in the antennae of M. scutellaris were: trichodea, basiconica, placodea, coeloconica, ampullacea and campaniformia. The most abundant sensilla found were trichodea and placoid in both castes and sexes. The ampullacea and coeloconica sensilla were found only in the distal flagellomeres of females and campiniformes and basiconica sensilla were not found in the analyzed antennae male. Larvae pre-defecant showed structures that are morphologically similar to sensilla. These structures has pores at its base and were found in many parts of the head area, which may represent an important gateway of volatile compounds from the larval food. xvii These compounds, possibly can activate genes involved in caste differentiation of Melipona scutellaris. The third chapter introduces the detection, cloning and sequencing of transcripts of the MscuCSP2, MscuCSP6, MscuOBP4 and MscuOBP8 genes from Melipona scutellaris larvae. We detected the MscuOBP8 protein in the L2, L3 (1-3), LPD LD larval stages of development using a monoclonal antibody selected by phage display. The 3D structure of the MscuOBP8 protein showed an internal cavity composed of hydrophobic amino acids confirming its binding function to hydrophobic compounds such as volatile substances. According to our data, the morphology of the head and especially adult antenna of the pre-defecating larvae (stage responsive to the action of juvenile hormone) and also the caracterization of genes and proteins of olfactory system in larvae of Melipona scutellaris can be correlated with caste differentiation mechanism in Melipona scutellaris proposed by Kerr.