RESUMEN
The objective of this study is to determine the role of carbohydrates on the toxic effect of parasporal inclusion proteins isolated from Malaysian mosquitocidal Bacillus thuringiensis (Bt) strains on erythrocytes (human and rat). Dose response analyses on the effect of these parasporal inclusions on human and rat erythrocytes suggest that toxin action is selective depending on bacterial strains and source of erythrocytes. Results from this study suggest Bt toxin is a lectin which recognizes specific plasma membrane glycoconjugate receptor(s) with a terminal residue of either D-mannose (Man), N-acetyl-D-galactosamine (GalNAc), N-acetyl-D-glucosamine (GlcNAc) or even a combination of these monosaccharides.
Asunto(s)
Animales , Bacillus thuringiensis/metabolismo , Proteínas Bacterianas/metabolismo , Relación Dosis-Respuesta a Droga , Eritrocitos/microbiología , Hemólisis , Humanos , Lectinas/metabolismo , Malasia , Monosacáridos/metabolismo , Control Biológico de Vectores/métodos , Ratas , Microbiología del Suelo , Especificidad de la Especie , Esporas Bacterianas/metabolismoRESUMEN
Alkaline activation of the spores of crystalliferous (Cry+) and acrystalliferous (Cry-) strains of Bacillus thuringiensis var israelensis; wild type B. cereus and its transcipient crystalliferous derivatives and wild type B. subtilis was studied. Also the effect of larval (Aedes aegypti) gut fluid on the activation of spores of these strains was studied. Only the spores of the crystal forming strains were found to be activated by 0.1 M K2CO3 (pH 10) and by the larval gut fluid. The process of alkaline activation was independent of whether crystals were present with the spores in the activation solution. This indicates that protoxin in the spore coat is responsible for the alkaline activation process and may have ecological implications for the organism.
Asunto(s)
Aedes/química , Animales , Bacillus thuringiensis/metabolismo , Proteínas Bacterianas/biosíntesis , Toxinas Bacterianas/biosíntesis , Humanos , Concentración de Iones de Hidrógeno , Larva/química , Esporas Bacterianas/metabolismoRESUMEN
En la presente comunicación, se propone una nuerva técnica de coloración para esporas bacterianas. La misma se logra con una mezcla de dos colorantes: Azul Nilo y Crisoidina y el uso de calor, para disminuir la resistencia natural de la espora a la penetración de los colorantes. Para la visualización del soma, se presentan tres alternativas: Una con tinta china negra, otra con Rojo Neutro o con Pironima B. Se detallan la preparación de los reactivos y de la técnica en cuestión y se trata de dar explicación al fundamento de esta nueva coloración