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

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.