295 resultados para Hymenoptera venom
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In a previous study, we showed that the Polybia paulista wasp venom causes strong myonecrosis. This study was undertaken to characterize the myotoxic potency of mastoparan (Polybia-MPII) isolated from venom (0.25 mu g/mu l) and injected in the tibial anterior (TA) muscle (i.m.) of Balb/c mice. The time course of the changes was followed at muscle degenerative (3 and 24 h) and regenerative (3, 7, and 21 days) periods (n = 6) after injection and compared to matched controls by calculation of the percentage of cross-sectional area affected and determination of creatine kinase (CK) activity (n = 10). The results showed that although NIP was strongly myotoxic, its capacity for regeneration was maintained high. Since the extent of tissue damage was not correlated with the CK serum levels, which remained very low, we raised the hypothesis that the enzyme underwent denaturation by the peptide. Evidence suggested that MP induced the death of TA fibers by necrosis and apoptosis and had the sarcolemma as its primordial target. Given its amphiphilic polycationic nature and based on the vast spectrum of functions attributed to the peptide, we suggest that MP interaction with cell membrane impaired the phosphorylation of dystrophin essential for sarcolemma mechanical stability, and disturbed Ca2+ mobilization with obvious implications on sarcoplasmic reticulum and mitochondrial functioning. (c) 2007 Elsevier Ltd. All rights reserved.
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Biochemical studies revealed that the activity of some hydrolytic enzymes from the venom glands of honey bee Apis mellifera was higher in workers of 14 days of age than in those of 40 days. Among these enzymes, the highest activity was recorded for acid phosphatase, which was cytochemically detected throughout the length of the secretory filament and surrounding the canaliculi of the distal region of the reservoir. The acid phosphatase was considered to be a typical secretion product, since it was present in the cytoplasm as well as in the canaliculi of the secretory cells. (c) 2009 Elsevier Ltd. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Cytochemistry studies of the nuclei of the venom glands' cells of worker bees of Apis mellifera indicated that there is a higher activity in the young workers while there is a predominance of degenerative characteristics in the older workers. In addition, we demonstrated that there is an occurrence of differential nuclear synthetic activities between the cells of the distal and the proximal regions of the secretory filament and of the venom reservoir. Signs of a higher nuclear activity were evidenced at the distal regions of this gland in 14-day old workers, while at the more proximal regions of the venom gland of 40-day old workers we identified the most obvious signs of degeneration. Therefore, it was evident that the process of glandular degeneration begins at the distal region of the venom gland instead of beginning at the proximal region as had been established previously. In addition, characteristics of nuclear synthetic activities were noted in the cells of the proximal region of the reservoir; these cells were thought to be non-secretory.
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The biochemical and functional characterization of wasp venom toxins is an important prerequisite for the development of new tools both for the therapy of the toxic reactions due to envenomation caused by multiple stinging accidents and also for the diagnosis and therapy of allergic reactions caused by this type of venom. PLA(1) was purified from the venom of the neotropical social wasp Polybia paulista by using molecular exclusion and cation exchange chromatographies; its amino acid sequence was determined by using automated Edman degradation and compared to the sequences of other vespid venom PLA(1)'s. The enzyme exists as a 33,961.40 da protein, which was identified as a lipase of the GX class, liprotein lipase superfamily, pancreatic lipases (ab20.3) homologous family and RP2 sub-group of phospholipase. P. paulista PLA(1) is 53-82% identical to the phospholipases from wasp species from Northern Hemisphere. The use restrained-based modeling permitted to describe the 3-D structure of the enzyme, revealing that its molecule presents 23% alpha-helix, 28% beta-sheet and 49% coil. The protein structure has the alpha/beta fold common to many lipases; the core consists of a tightly packed beta-sheet constituted of six-stranded parallel and one anti-parallel beta-strand, surrounded by four alpha-helices. P. paulista PLA(1) exhibits direct hemolytic action against washed red blood cells with activity similar to the Cobra cardiotoxin from Naja naja atra. In addition to this, PLA(1) was immunoreactive to specific IgE from the sera of P. paulista-sensitive patients. (c) 2007 Elsevier Ltd. All rights reserved.
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The venom gland of queens of Apis mellifera was examined through light and transmission electron microscopy and subjected to electrophoretic analyses. Virgin queens exhibited prismatic secretory cells containing large amounts of rough endoplasmic reticulum with dilated cisternae, open secretory spaces, numerous vacuoles and granules scattered in the cytoplasm, and spherical nuclei with numerous nucleoli. The secretion produced was non-refringent under polarized light and the electrophoretic analysis of glandular extracts revealed five main protein bands. In mated queens, the venom gland exhibited a high degree of degeneration. Its secretion was refringent under polarized light and one of the main bands was absent in the electrophoretic pattern obtained. The morphological aspects observed are in agreement with the function of this gland in queens, given that virgin queens use venom in battles for the dominance of the colony, a situation that occurs as soon as they emerge, while fertilized queens rarely use venom. (c) 2006 Elsevier Ltd. All rights reserved.
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The present paper aimed at testing the action of non-lyophilized venom of Africanized bees Apis mellifera through topical applications on Diatraea saccharalis egg masses. The CL50, DL50 and the most susceptible age of eggs to the venom topic application were also determined. Three-day-old eggs were the most susceptible to the venom action with CL50 equal to 8.6 mg/ml and DL50 equal to 0.173 mg/mass. The venom loses its action after being stored for 15 days.
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Histological analyses were made in order to evaluate the effects of the topic application of a synthetic juvenile hormone (JH-III Sigma) on the development of the venom glands in workers of Apis mellifera. Three experimental groups were used: the first received 1 μl of a dilution of the juvenile hormone in hexane (2μg/μl); the second group received 1 μl of hexane; and the third group, the control, did not receive any kind of treatment. The application was made on larvae at the beginning of the fifth instar and the glands were collected at different developmental stages. The results showed that the application of the diluted hormone, as well as the hexane alone, accelerated gland development in relation to the control group at all developmental stages studied. These data suggest that the juvenile hormone acts on the development of the venom gland; nevertheless, this action could be amplified by the effect of the solvent used in the present work, as well as in other studies concerning this matter.
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The present investigation analyzed the influence of Juvenile Hormone (JH) on the venom glands of Apis mellifera workers through protein dosage and electrophoresis of venom gland extracts of newly emerged workers which were treated with 1 μl JH dissolved in hexane, in concentration of 2μg/μl. Newly emerged workers non-treated and treated with 1 μl hexane were the controls. Both JH and hexane provoke quantitative changes on the gland protein titre and on the protein electrophoretic profile. The disappearance of protein bands in the venom gland extracts of 14 day-old treated workers, a situation normally found only in 35 day-old non-treated workers, suggests that the JH treatment induces a precocious maturation of the worker venom gland.
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The venom glands of worker ants of the species Ectatomma quadridens morphologically resemble an elongated sac or reservoir ending in a narrower portion that has the function of releasing the secretion to the exterior. Two external secretory filaments are individually inserted into the proximal portion of the gland and end inside the convoluted gland. The venom gland of workers of E. quadridens is, therefore, morphologically subdivided into four distinct portions: a) sac-shaped reservoir measuring approximately 1mm in length; b) excretory duct, proximal portion of the reservoir that joins the gland to the sting apparatus; c) convoluted gland, final portion of the external secretory filaments located inside the reservoir; and d) two secretory filaments measuring about 2 mm in length; their free extremities end blindly and are individually inserted into the reservoir wall at the proximal region of the venom gland. The histological data showed that the filaments and the convoluted gland are composed of cubic cells of secretory function. The reservoir consists of a simple cubical epithelium externally surrounded by muscle fibers. A thick cuticle internally coats the epithelium of the reservoir. The application of histochemical tests allowed us to establish that the final secretion of the venom gland of Ectatomma quadridens is of glycoproteic nature. This secretion undergoes several modifications at the secretory filaments, at the convoluted gland, and in the reservoir before reaching the excretory duct, the point at which the secretion is released in its final composition, namely the venom. Based on the differences among various Ponerinae species we propose a hypothesis suggesting a probable evolutionary process that the venom glands of members of this subfamily might have undergone.
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This paper describes the ultramorphology and histology of the venom reservoir in 14-day old workers of Apis mellifera, immediately before and after the application of electrical shocks with the object of causing venom elimination and reservoir collapse. The external epithelial surface of the reservoir was differentiated according to its morphological aspects into posterior, median, and proximal or duct regions at the ventral surface and into anterior and posterior regions at the dorsal surface. While the epithelium of the proximal region forms a ventral infolding, a dorsal salience is formed at this region. These structures and the epithelial regions persist both in full and empty reservoirs. The reservoir appeared full and distended before the electrical shocks were applied and became empty and withered afterwards due to the elimination of the secretion, without any reductions in length. Nevertheless, some secretion was kept inside the lumen, thus suggesting a possible role for the reservoir in the modification of the secretion.
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Fire ants are aggressive Neotropical ants that are extensively similar in general biology and morphology, making species identification difficult. Some fire ant species are top-rated pests spreading throughout the world by trade vessels. Many researchers attempted to sort between invasive and native species by using chemical characters, including patterns of venom alkaloids. The present study is the first to report intraspecific variation in some chemical characters, namely, cuticular hydrocarbons and venom alkaloids, within the Brazilian fire ant species Solenopsis saevissima and also reports on within-nest variations among members of different castes. Two different haplotypes (cryptic species) of S. saevissima were clearly identified, one presenting a predominant combination of the venom alkaloids cis- and trans-2-methyl-6-undecylpiperidine with the cuticular hydrocarbons C23, 3-Me-C23, 10-C 25:1, C25, and 3-Me-C25, and the other a predominant combination of cis- and trans-2-methyl-6-tridecenylpiperidine with predominance of 12-C25:1, C25, 11-Me-C25, 3-Me-C25, 13-C27:1, C27, and 13-Me-C 27. Intranest variations revealed that the proportions among these compounds varied sensibly among workers of different sizes, gynes, and males (no alkaloids were detected in the latter). Larva contained vestiges of the same compounds. The recorded chemical profiles are quite different from previous reports with S. saevissima samples from So Paulo. The finds thus support other recent claims that S. saevissima includes cryptic species; the study, moreover, adds the find that they can occur in the same geographical location. © 2012 Eduardo Gonalves Paterson Fox et al.
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In this study, we describe the cDNA cloning, sequencing, and 3-D structure of the allergen hyaluronidase from Polybia paulista venom (Pp-Hyal). Using a proteomic approach, the native form of Pp-Hyal was purified to homogeneity and used to produce a Pp-specific polyclonal antibody. The results revealed that Pp-Hyal can be classified as a glycosyl hydrolase and that the full-length Pp-Hyal cDNA (1315 bp; GI: 302201582) is similar (80-90%) to hyaluronidase from the venoms of endemic Northern wasp species. The isolated mature protein is comprised of 338 amino acids, with a theoretical pI of 8.77 and a molecular mass of 39,648.8 Da versus a pI of 8.13 and 43,277.0 Da indicated by MS. The Pp-Hyal 3D-structural model revealed a central core (α/β)7 barrel, two sulfide bonds (Cys 19-308 and Cys 185-197), and three putative glycosylation sites (Asn79, Asn187, and Asn325), two of which are also found in the rVes v 2 protein. Based on the model, residues Ser299, Asp107, and Glu109 interact with the substrate and potential epitopes (five conformational and seven linear) located at surface-exposed regions of the structure. Purified native Pp-Hyal showed high similarity (97%) with hyaluronidase from Polistes annularis venom (Q9U6V9). Immunoblotting analysis confirmed the specificity of the Pp-Hyal-specific antibody as it recognized the Pp-Hyal protein in both the purified fraction and P. paulista crude venom. No reaction was observed with the venoms of Apis mellifera, Solenopsis invicta, Agelaia pallipes pallipes, and Polistes lanio lanio, with the exception of immune cross-reactivity with venoms of the genus Polybia (sericea and ignobilis). Our results demonstrate cross-reactivity only between wasp venoms from the genus Polybia. The absence of cross-reactivity between the venoms of wasps and bees observed here is important because it allows identification of the insect responsible for sensitization, or at least of the phylogenetically closest insect, in order to facilitate effective immunotherapy in allergic patients. © 2013 Elsevier Ltd.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)