Nucleopolyhedrovirus: scanning electron microscopy technique

A simplified methodology was developed to study the geometric form of multiple Bombyx mori Nucleopolyhedrovirus by scanning electron microscopy. The virus belongs to Baculoviridae family and was isolated from the silkworm Bombyx mori (L.) (Lepidoptera: Bombycidae). The polyhedra of Nucleopolyhedrovirus were obtained from the filtrate, inoculum and hemolymph of the silkworm experimentally infected with nuclear polyhedra. This material was placed on stubs, where a copper tape was previously adhered. After dry at room temperature the virus was covered with carbon and gold. Scanning electron microscopy analysis reveled a well defined morphology for the polyhedra of multiple Bombyx mori Nucleopolyhedrovirus, making possible the mathematical study that identified it as a truncated octahedron. The form of the polyhedron can present taxonomic value, once it is specific for each viral lineage.

Um método simples foi desenvolvido para se estudar a forma geométrica do Bombyx mori Nucleopolyhedrovirus múltiplo, BmMNPV, para microscopia eletrônica de varredura. O vírus, pertencente à Família Baculoviridae, foi obtido do filtrado, do inóculo e da hemolinfa de lagartas de Bombyx mori (L.) (Lepidoptera: Bombycidae) infectadas. O material foi colocado diretamente sobre o suporte de varredura, onde previamente foi aderida uma fita de cobre. Após secagem e metalização com carbono e ouro, o vírus foi analisado ao microscópio de varredura. Os poliedros apresentaram-se com as faces lisas, perfeitamente definidas, possibilitando a análise matemática que o identificou como um octaedro truncado. A forma do poliedro pode apresentar valor taxonômico, uma vez que ela é específica para cada linhagem viral.

Nucleopolyhedrovirus infected central nervous system cells of Bombyx mori ( L. ) ( Lepidoptera: Bombycidae )

O Nucleopolyhedrovirus é um vírus que infecta uma série de insetos, como o bicho-da-seda, Bombyx mori (L.). Um isolado geográfico do vírus, o Bombyx mori Nucleopolyhedrovirus múltiplo (BmMNPV), foi utilizado para se analisar a citopatologia em células do sistema nervoso central (SNC) de lagartas de B. mori. O BmMNPV foi inoculado experimentalmente e segmentos do tecido nervoso foram processados para microscopia de luz e microscopia eletrônica de transmissão. Células do SNC (nervosas, gliais e do perineuro) revelaram indícios de infecção no 5° dia pós-inoculação com o BmMNPV, cujas características citopatológicas foram: hipertrofia nuclear, presença do estroma virogênico, onde são sintetizados os virions, e formação dos poliedros. Não foi observada lise das células do SNC infectadas, uma característica das infecções pelo NPV; contudo, poliedros maduros foram evidenciados em espaços nos gânglios e conectivos nervosos. Esses poliedros possivelmente são oriundos das traquéias que penetram no sistema nervoso, e suas células, susceptíveis ao BmMNPV, sofrem lise após infecção. Os resultados indicam, ainda, que o sistema traqueal é responsável pela dispersão da infecção causada pelo BmMNPV no SNC de lagartas de B. mori. Neste sentido, os ramos que formam o sistema traqueal possibilitam o rompimento da barreira hemolinfa/sistema nervoso, permitindo que os virions tenham acesso 'a matriz extracelular do SNC e, conseqüentemente, às suas células constituintes.

Morphoquantitative effects of acute diabetes on the myenteric neurons of the proximal colon of adult rats

The effects of acute diabetes on the density and size of the myenteric neurons of the proximal colon of adult rats were investigated. The injection of streptozotocin was followed by a period of observation of seven days, during which the diabetic animals showed weight loss, excessive food and water intake, large urinary debt and hyperglicemia. The whole-mounts from the proximal colon were stained with the techniques of Giemsa and of the NADH-diaphorase, and the employment of these techniques made it possible to verify a decrease on the neuronal density and on the cell body size of the myenteric neurons in the colon of the diabetic rats. These observations were discussed in terms of the pathophysiology of the diabetes and the experimental protocol

Evaluation of the areas of neuronal cell bodies and nuclei in the myenteric plexus of the duodenum of adult rats

This study compared the areas of cell body and nucleus profiles of the myenteric neurons in the antimesenteric and intermediate regions of the duodenum of adult rats. Five male rats were used. The duodenum was removed and dissected to whole-mount preparations, which were stained by the Giemsa technique. The areas of cell body and nucleus profiles of 100 neurons, 50 from each region, of each animal, were assessed with image analyser. Based on the global mean +/- SD of the areas of cell body profiles, neurons were labelled as small, medium or large. It was observed that the neurons did not differ significantly in size or incidence between the antimesenteric and intermediate regions. However, the nuclei of the small and medium neurons were significantly smaller in the latter region. It is discussed that the smaller nuclear size could be related to the cell bodies being slightly smaller on this region and to a possible smaller biosynthetic activity which would influence nuclear size.

Number and size of myenteric neurons of the duodenum of adult rats with acute diabetes

This study had as its purpose to assess the effects of acute diabetes induced by streptozotocin (35 mg/kg body weight) on the number and size of the myenteric neurons of the duodenum of adult rats considering equally the antimesenteric and intermediate regions of the intestinal circunference. Experimental period extended for a week. Neuronal counts were carried out on the same number of fields of both regions of the duodenal circunference and measurements of neuronal and nuclear areas on equal numbers of cells. Number and size of the myenteric neurons stained with Giensa were not significantly different between groups. On the other hand, the proportion of NADH-positive neurons increased from 18.54 per cent on the controls to 39.33 per cent on the diabetics. The authors discuss that this increased reactivity probably results from a greater NADH/NAD* ratio, described in many tissues of diabetic animals, which has consequences on the modulation of the enzymes that use these cofactors and whose activity is detected by the NADH-diaphorase technique.

Neuron number in the myenteric plexus of the ascending colon of rats

We carried out this study with the purpose of comparing the neuronal density in antimesocolic and intermediate regions of the colon of rats. We used the ascending colon of ten seven-months of Wistar rats. With the Giemsa method we found 29046 neurons/cm2 on the antimesocolic region and 30968 neurons/cm2 on the intermediate regions. With the NADH-diaphorase technique 12308 neurons/cm2 on the antimesocolic regions and 8798 neurons/cm2 on the intermediate regions were evidenced. The number of NADH-diaphorase positive neurons is significantly less than the number of Giemsa-stained neurons, and that this difference is enhanced on the intermediate regions of the intestinal circumference. Therefore, to compared the number of neurons of an intestinal segment of a same species at the same age, it is necessary to take into consideration the technique employed and the region of the intestinal circumference from where the sample was obtained.

Effect of maternal protein deprivation on morphological and quantitative aspects of the myenteric plexus neurons of proximal colon in rats

We have studied the morphological and quantitative aspects of the myenteric plexus neurons of the proximal colon in rats (Rattus norvegicus of Wistar strain) submitted to a protein deprivation during prenatal and lactation periods. Twenty pregnant dams were divided in four groups labeled according to the kind of nourishment they were given: Group NN, normal diet; Group DN, low protein diet during prenatal period, and normal diet during lactation period;Group ND, normal diet during prenatal period, and low protein diet during lactation period; Group DD, low protein diet during prenatal and lactation periods. Histological analyses were developed with proximal colon segments using the haematoxylin and eosin staining method. Membrane preparations were stained by Giemsa'smethod. The statistical analysis has demonstrated no sgnificant difference amongthe means of neurons found in the four studied groups. It was noticed that the animals under protein deprivation during prenatal and lactation periods presentedgreater quantity of large and strongly basophilic myenteric neurons. This suggests that neurons have accumulated protein in the cytoplasm.

Effects of maternal proteic undernutrition on the neurons of the myenteric plexus of the duodenum of rats

The purpose of this study was to verify the effects of proteic undernutrition on the neurons of the myenteric plexus from the duodenum of Wistar rats. Twenty-four animals at the age of 60 days were divided iii four groups, which were named according to the period their mothers received hypoproteic ration (8 per cent). Some segments of duodenum were subjected to histological treatment and stained with hematoxilin-eosin and some were used for whole mount preparations stained with Giemsa. We observed small, medium-sized and large neurons grouped in ganglia of various shapes. It was concluded that the maternal proteic undernutrition does not affect the organization of the myenteric plexus and that animals submitted to undernutrition does not affect the organization of the myenteric plexus and that animalssubmitted to undernutrition during gestation and lactation, wheil nornlally fed, sliow iielirons with strongly basophilic cytoplasin aiid larger cellul@ir bodies than tliose from control animals.