Morphological alterations induced by boric acid and fipronil in the midgut of worker honeybee (Apis mellifera L.) larvae

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Virus present in the reproductive tract of asymptomatic drones of honey bee (Apis mellifera l.), and possible infection of queen during mating

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mastoparan effects in skeletal muscle damage: An ultrastructural view until now concealed

Animal venoms have been valuable sources for development of new drugs and important tools to understand cellular functioning in health and disease. The venom of Polybia paulista, a neotropical social wasp belonging to the subfamily Polistinae, has been sampled by headspace solid phase microextraction and analyzed by gas chromatography-mass spectrometry. Recent study has shown that mastoparan, a major basic peptide isolated from the venom, reproduces the myotoxic effect of the whole venom. In this study, Polybia-MPII mastoparan was synthesized and studies using transmission electron microscopy were carried out in mice tibial anterior muscle to identify the subcellular targets of its myotoxic action. The effects were followed at 3 and 24 h, 3, 7, and 21 days after mastoparan (0.25 mu g/mu L) intramuscular injection. The peptide caused disruption of the sarcolemma and collapse of myofibril arrangement in myofibers. As a consequence, fibers presented heteromorphic amorphous masses of agglutinated myofilaments very often intermingled with denuded sarcoplasmic areas sometimes only surrounded by a persistent basal lamina. To a lesser extent, a number of fibers apparently did not present sarcolemma rupture but instead appeared with multiple small vacuoles. The results showed that sarcolemma, sarcoplasmic reticulum (SR), and mitochondria were the main targets for mastoparan. In addition, a number of fibers showed apoptotic-like nuclei suggesting that the peptide causes death both by necrosis and apoptosis. This study presents a hitherto unexplored view of the effects of mastoparan in skeletal muscle and contributes to discuss how the known pharmacology of the peptide is reflected in the sarcolemma, SR, mitochondria, and nucleus of muscle fibers, apparently its subcellular targets.

3D reconstruction and scanning electron microscopy of salivary glands of the millipede Rhinocricus padbergi (Verhoef, 1938) (Diplopoda: Spirobolida)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ultrastructural Alterations in the Midgut of Diplopods after Subchronic Exposure to Substrate Containing Sewage Mud

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Molecular and ultrastructural profiles of the symbionts in Cephalotes ants

The molecular and ultrastructural profiles of the symbionts found in the midgut and ileum of Cephalotes atratus, Cephalotes clypeatus, and Cephalotes pusillus were determined using the V3 region of the bacterial 16S rDNA gene and transmission electron microscopy (T.E.M.). Two samples of C atratus, three of C clypeatus, and six of C. pusillus were analyzed. The coefficients of similarity ranged from 80% to 94% for the samples of symbionts from C. clypeatus and C. atratus, despite being collected in geographically distant sites. The variability within symbionts found in the samples of C. pusillus varied from 29% to 55%, in samples geographically close as well as distant. PCR-DGGE was effective for the purpose of this study and can be considered a versatile tool to analyze gut microbiota. Details of the ultrastructural aspect of these bacteria are presented. (C) 2010 Elsevier Ltd. All rights reserved.

Silk formation mechanisms in the larval salivary glands of Apis mellifera (Hymenoptera : Apidae)

The mechanism of silk formation in Apis mellifera salivary glands, during the 5th instar, was studied. Larval salivary glands were dissected and prepared for light and polarized light microscopy, as well as for scanning and transmission electron microscopy. The results showed that silk formation starts at the middle of the 5th instar and finishes at the end of the same instar. This process begins in the distal secretory portion of the gland, going towards the proximal secretory portion; and from the periphery to the center of the gland lumen. The silk proteins are released from the secretory cells as a homogeneous substance that polymerizes in the lumen to form compact birefringent tactoids. Secondly, the water absorption from the lumen secretion, carried out by secretory and duct cells, promotes aggregation of the tactoids that form a spiral-shape filament with a zigzag pattern. This pattern is also the results of the silk compression in the gland lumen and represents a high concentration of macromolecularly well-oriented silk proteins.

A comparative cytochemical study of the dufour gland in the eusocial bee Apis mellifera Linne, 1758 and Melipona bicolor Lepeletier, 1836

Dufour glands of Apis mellifera and Melipona bicolor were studied under light and transmission electron microscopy, using the cytochemical techniques of mercury bromophenol blue for protein detection, imidazole-buffered osmium tetroxide selective staining of unsaturated lipids, lanthanum nitrate for intercellular junction identification and zinc-iodide-osmium tetroxide for cytoplasmic endomembrane visualization. The results in both species corroborated the lipid nature of the gland secretion and showed in A. mellifera the poverty of the synthetic machinery in the worker gland cells in comparison with the queen, as expected by previous biochemical analyses. The pathway of the exogenous compounds of the secretion is intracellular, since substances can penetrate the cell folds and intercellular junctions, but their access to the, gland lumen is barred by the apical intercellular junctions.

Ultrastructural aspects of the mandibular gland of Melipona bicolor Lepeletier, 1836 (Hymenoptera : Apidae, Meliponini) in the castes

The mandibular gland in Melipona bicolor workers and queens was studied by scanning and transmission electron microscopy. There is no difference in the gland anatomy between the castes, but the transmission electron microscopy showed variation of the cellular ultrastructure according to the secretory phase of the gland in both castes. Smooth endoplasmic reticulum was abundant in the secretory cells of physogastric queens, indicating that these cells produce lipid secretion that is stored in granules with multi-lamellar bodies. Mitochondrial variations during the cell secretory cycle indicates their participation in the lipid synthesis. After secretion, release in the reservoir lumen through the collecting canals, the secretory cells contain many myelinic bodies, indicative of cellular regression. (C) 2004 Elsevier Ltd. All rights reserved.

Nuclear activity in Apis mellifera L. (Hymenoptera, Apidae) queen ovary cells demonstrated by silver nitrate impregnation and ultrastructure

Este estudo mostra, por meio de microscopia convencional, impregnação por nitrato de prata e microscopia eletrônica de transmissão, as mudanças que ocorrem na atividade nuclear de células do ovário durante a vitelogênese de Apis mellifera (Linnaeus, 1758). Material impregnado por nitrato de prata foi detectado no núcleo de células nutridoras, na vesícula germinal do ovócito e no núcleo das células foliculares. As maiores quantidades de material impregnado pela prata foram observadas durante as fases de maior atividade dessas estruturas. A impregnação por prata permitiu demonstrar que a vesícula germinal sintetiza ribonucleoproteínas (RNP) durante o início da vitelogênese. A ultraestrutura mostrou que o material impregnado apresenta características morfológicas de nucléolos.

Tissue evidence of the testosterone role on the abnormal growth and aging effects reversion in the gerbil (Meriones unguiculatus) prostate

Prostate differentiation during embryogenesis and its further homeostatic state maintenance during adult life depend on androgens. Abundant biological data suggest that androgens play an important role in the development of the prostate cancer and other prostatic diseases. The objective of this work was to evaluate the effects of the testosterone supplementation in gerbil (a new experimental model) at different ages. Tissues from experimental animals were studied by histological and histochemistry procedures, androgen receptor immunohistochemistry assay, morphometric-stereological analysis, and transmission electron microscopy (TEM). After the treatment were observed increase of prostate weight and epithelium height in all ages studied. In some adult and aged treated animals, hyperplasic and displasic process were observed, including prostatic intraepithelial neoplasias and adenocarcinomas. Increase of the thickness of the smooth muscle cell (SMC) layer was observed in pubescent and adult animals and TEM revealed apparent SMC hypertrophy. An apparent increase in the frequency of blood vessels distributed by the subepithelial stroma in the treated animals was noticed. Reversion of the natural effects of aging on the prostate was observed in the aged treated animals in some acini of the gland. These data demonstrate that the gerbil prostate is susceptible to androgenic action at the studied ages and it can serve, for example, as experimental model to studies of prostate neoplasic process induction and hormonal therapy in aged animals.

Tissue alterations in the Guinea pig lateral prostate following antiandrogen flutamide therapy

The flutamide antiandrogenic effects oil the Guinea pig male prostate morphology in puberal, post-puberal and adult ages were evaluated in the present study. Daily-treated group animals received flutamide Subcutaneous injection at a dose of 10 mg/Kg body weight for 10 days. The control group animals received a pharmacological vehicle under the same conditions. The lateral prostate was removed, fixed and processed for light and transmission electron microscopy. The results revealed all increase of the acinus diameter in the treated puberal animals and straitness in the stromal compartment around the acini. The epithelial cells exhibited cubic phenotype. In the post-puberal and adult animals, a decrease of the acinus diameter was observed, as well as an increase of the smooth muscle layer and presence of the folds at epithelium. The ultrastructural evaluation of the secretory cells in the treated group demonstrated endomembrane enlargement, mainly in the rough endoplasmic reticulum and Golgi apparatus. In addition, a decrease of the microvilli and alterations in the distribution patterns and density of the stromal fibrillar components were observed. In Conclusion, the flutamide treatment exerts tissue effects oil the lateral prostate, promoting stroma/epithelium alterations.

Spontaneous germ cell death by apoptosis in epididymis of the adult bat Artibeus lituratus

Many factors can lead cells to apoptosis during the various stages of cell life. This study was undertaken to characterize germ cell death in the epididymis of the adult Artibeus lituratus by histochemical and immunohistochemical techniques using light microscopy and transmission electron microscopy. The results showed that cells with a nuclear phenotype and ultrastructural characteristics of chromatin compaction were common in apoptosis. The Apoptag test confirmed that the suspected cells were apoptotic. It is suggested that immature germ cells, when released from the germinative epithelium, may be directed towards the epididymis instead of being disposed of in the testicle. Furthermore, intact immature cells can leave the testicle in the initial phases of apoptosis and complete this phenomenon in the epididymis.

Chromatoid body: Remnants of nucleolar proteins during spermatogenesis in triatomine (Heteroptera, Triatominae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cellular changes in the prostatic stroma of glucocorticoid-treated rats

Glucocorticoid hormones (GCs) have been widely used for the treatment of prostate cancer because of their inhibitory property against tumour growth. However, their mechanism of action in the prostate has received little attention. Excess GCs can lead to peripheral insulin resistance resulting in hyperglycaemia and hyperinsulinaemia. Insulin plays an important role as a cellular stimulant and high levels are related to low levels of androgens. Our objective has been to describe the effects of insulin resistance induced by dexamethasone treatment on the morphology of rat ventral prostate. Mate adult Wistar rats received daily intraperitoneal injections of dexamethasone or saline for five consecutive days after which the rats were killed and the ventral prostate was removed, weighed and prepared for conventional and transmission electron microscopy (TEM). Dexamethasone treatment resulted in atrophy and decreased proliferative activity of prostatic epithelial cells. TEM analysis revealed changes in the epithelium-stroma interface, with some interruptions in the basement membrane. Fibroblasts showed a secretory phenotype with dilated endoplasmic reticulum. Smooth muscle cells exhibited a contractile pattern with 50% atrophy, an irregular membrane and twisted nuclei. Mitochondrial alterations, such as enlarged size and high electron density in the mitochondrial matrix, were also detected in smooth muscle cells. Insulin resistance induced by dexamethasone is thus associated with epithelial atrophy similar to that described for diabetic rats. However, GCs are responsible for morphological changes in the stromal cell population suggesting the activation of fibroblasts and atrophy of the smooth muscle cells.