Caracterização da glândula de veneno da abelha Xylocopa frontalis (Hymenoptera, Apidae, Xylocopini) para aplicações biotecnológicas e farmacêuticas: uma investigação histológica, histoquímica e de perfil proteico

Abstract

Hymenoptera have an estimated population of over one million species. Their iron and associated structures have been studied since the 17th century, but most research has focused on a few species of social bees. The venoms of non-social bees are still poorly explored, and the only studies on Xylocopa toxins have analyzed foreign species. The bioprospecting of these venoms for the pharmaceutical industry is of biotechnological interest. In this context, the present study focuses on the characterization of the venom gland of native non-social bees of the species Xylocopa frontalis. The general objective of the present study is to perform a histological and histochemical analysis of the venom glands of the non-social bee X. frontalis, in comparison with the eusocial bee Apis mellifera, together with an evaluation of the protein component profile of the venom of X. frontalis. For this purpose, after a collection, carried out in the region of Sorocaba - SP, and anesthetized insects, the venom glands were dissected and subsequently introduced into 4% paraformaldehyde. After fixation, the organs were dehydrated in solutions with increasing concentrations of alcohol, embedded in historesin, and subsequently submitted to microtomy to obtain histological and histochemical slides, stained with hematoxylin-eosin for morphological characterization and to different histochemical stains (P.A.S., Bromophenol Blue, Xylidine Ponceau and Sudam Black) for detection of carbohydrate, protein and lipid macromolecules. A histochemical quantification of proteins by pixel intensity was performed using Xylidine Ponceau, with statistical analysis in the R software. Protein dosage of the venom glands of X. frontalis and A. mellifera was performed using the Bradford method, and the comparison of concentrations was performed via bootstrapping. For protein characterization, SDS-PAGE was used, analyzing the mobility of the bands in gel and determining the molecular mass by linear regression in Excel. In X. frontalis, the venom apparatus is 5 times larger than in A. mellifera, with a reservoir and a gland adapted for defense with greater muscular abundance, which preserves the permanence of the apparatus. Histochemical staining indicates protein predominance in both species, with no presence of lipids. A. mellifera has an 8.5 times higher concentration of proteins in the total extract, while X. frontalis has less technical protein binding in the lumen of the venom gland reservoir, with the presence of proteins with molecular masses indicative of being lectins, serine proteases and multimeric proteins.