Revista de Biología Tropical Vol.34 (2)
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Ítem Estudios sobre la estabilidad del virus del rayado fino del maíz por degradación enzimática del ARN viral y microscopia electrónica de las partículas(1986) Pereira Reyes, Reinaldo; León Azofeifa, PedroThe stability of "Maize Rayado Fino Virus" capsids was studied correlating enzymatic degradation analysis of the RNA in full capsids with electron microscopy of negatively stained particles. The great thermal stability of pancreatic ribonuclease A, combined with the strong change in absorbance of the nucleic acids upon hydrolisis, provide a convenient assay for RNA release, which correlates with quantitative observations of the particles in the electron microscope. A repeatable transition between 75° and 80°C is observed with MRFV, presumably due to cooperative opening of the closed shell, followed by the release of the encapsidated RNA.Ítem Una doble infección viral en orquídeas del género Cymbidium(1986) Velasco, Ana Cecilia; Hernández Chavarría, Francisco; Gámez Lobo, RodrigoA double -viral infection in Cymbidium hybrids is described. Virions were discovered by negative staining of sick plant sap, which showed a rigid type and a flexible virus. Two types of viral-cytoplasmatic inclusions, corresponding to both viruses, were observed in the ultrafine cuts of injured foliar areas. In one cell two types of inclusions were found together. By ultracentrifugation in sacharose gradients, these two types of virions could not be completely separated, probably due to their fragmentation and aggregation. The rigid virus was related to the orchid race of tobacco mosaic virus, the flexible to the cymbidium mosaic virus. They affect orchids by producing a clinical case, which includes chlorotic and necrotic striate mosaics.Ítem Inflammatory infiltrate in skeletal muscle injected with Bothrops asper venom(1986) Gutiérrez, José María; Chaves Mora, Fernando; Cerdas Fallas, LuisThe time-course and composition of inflammatory infiltrate in mouse gastrocnemius injected with Bothrops asper venom was studied. The venom induced myonecrosis, and a prominent decrease in muscle levels of creatine kinase (CK) as early as 3 hr after envenomation. Inflammatory infiltrate was scarce by 6 hr. but increased markedly at 24, 48 and 72 hr. Samples of infiltrate obtained at 6 and 24 hr contained polymorphonuclear leucocytes as the predominant cell type, whereas at 48 hr and 72 hr the relative number of macrophages increased. Inflammatory cells were located within necrotic muscle cells, as well as in the interstitial space, but there were some necrotic areas devoid of inflammatory cells even one week after envenomation. When correlating the presence of inflammatory cells with degradation of myofibrillar proteins, it was observed that at 6 hr there was little muscle protein degradation. By 48 hr a decrease in "non collagen" proteins was observed, together with a reduction in some myofibrillar components, as judged by electrophoresis. Proteolytic enzymes of inflammatory cells may play an important role in myofibrillar protein degradation after myonecrosis induced by B. asper venom.