Atomic Force Microscopy of spermidine-induced DNA condensates on silicon surfaces

In the present work, we show that oxidized silicon may be successfully used to image multivalent cation-induced DNA condensates under the Atomic Force Microscope (AFM). The images thus obtained are good enough, allowing us to distinguish between different condensate forms and to perform nanometer-sized measurements. Qualitative results previously obtained using mica as a substrate are recovered here. We additionally show that the interactions between the cation spermidine (the condensing agent) and the DNA molecules are not significantly disturbed by the silicon surface, since the phase behavior of an ensemble of DNA molecules deposited on the silicon substrate as a function of the cation concentration is very similar to that found in solution

Caracterização eletroforética e análise de subgrupo de rotavírus em rebanhos bovinos leiteiros do Estado de São Paulo

Foi realizado um estudo para determinar a ocorrência de infecção por rotavírus em rebanhos bovinos leiteiros. Foram analisadas 375 amostras de fezes de bezerros, na faixa etária 1 a 45 dias, provenientes de animais pertencentes a nove propriedades rurais, situadas em seis municípios da região nordeste do Estado de São Paulo. Destas, 193 pertenciam a animais com diarréia e 182 foram obtidas de animais clinicamente sadios. As técnicas utilizadas para a detecção de rotavírus foram o ensaio imunoenzimático (EIE) e a eletroforese em gel de poliacrilamida (EGPA). Por meio do EIE foram detectadas 11,2% (42/375) de amostras positivas, 15% delas (29/193) obtidas de animais com diarréia e 7,1% (13/182) colhidas de animais sem diarréia. A análise do perfil do genoma indicou a presença de seis eletroferótipos distintos, característicos de rotavírus do grupo A. Um único eletroferótipo foi detectado em três rebanhos, o qual permaneceu constante durante o período de amostragem. em dois rebanhos diferentes eletroferótipos foram detectados, embora com maior prevalência de um dado perfil. A caracterização das amostras positivas em subgrupos foi realizada por meio do EIE com duplo sanduíche, utilizando-se anticorpos monoclonais (MAb) específicos para antígenos de subgrupo (I e II). Foram caracterizadas como subgrupo I 52,4% (22/42) das amostras testadas, nenhuma reagiu com MAb de subgrupo II, enquanto as demais, 47,6% (20/42), não reagiram com nenhum dos dois subgrupos.A study was accomplished to determine the occurrence of rotavirus in feces of calves, in the State of São Paulo, Brazil. A total of 375 samples of feces from calves 1 to 45 day-old were collected. The animals belonged to farms situated in six counties of the northeast region of the State. One hundred and ninety tree out of these samples belonged to animals with a clinical picture of diarrhea and 182 were obtained from clinically healthy animals. The techniques used for the detection of rotavirus were the enzyme immunoassay (EIA) and the polyacrilamide gel electrophoresis (PAGE). By the use of EIA, 11.2% (42/375) of the samples were positive for rotavirus. Among the samples of diarrheic calves, 15% (29/193) were found to be positive for rotavirus, whereas 7.1 (13/182) positive samples were obtained from clinically healthy animals. The PAGE test presented a lower sensitivity than EIA, since from the 42 positive samples in EIA, only 36 presented an electrophoretical profile characteristic of rotavirus. The genome analysis indicated the presence of six distinct electrophoretical types characteristic of group A rotavirus. A unique electropherotype was detected in tree farms, which remained constant during the sampling period. In two farms a second electropherotype was detected. The serological characterization of the positive samples in subgroups was accomplished through EIA with double sandwich, utilizing monoclonal antibodies ( I and II). Twenty two group A rotavirus strains I (52.4%, 22/42) reacted with MAb of subgroup I, none to subgroup II, and the remaining 47.6% (20/42) did not react with the two subgroups

Saposin fold revealed by the NMR structure of NK-lysin.

NK-lysin is the first representative of a family of sequence related proteins--saposins, surfactant-associated protein B, pore forming amoeba proteins, and domains of acid sphingomyelinase, acyloxyacylhydrolase and plant aspartic proteinases--for which a structure has been determined.LetterResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe