RESUMO
Samples of the Bacillus thuringiensis (Bt) were collected from soil and insects. Eight isolates were selected from rural soil, 15 from urban soil and 11 from insects. These were evaluated for entomopathogenicity against larvae of Anticarsia gemmatalis and Culex quinquefasciatus. The pathogenicity tests showed that a higher percentage of isolates were active against A. gemmatalis (60%) compared to C. quinquefasciatus (31%). Probit analysis (LC50) indicated that against A. gemmatalis four of the isolates presented values similar to the reference strain against A. gemmatalis, while against C. quinquefasciatus one isolate showed an LC50 similar to the reference strain (IPS-82). SDS-PAGE characterisation of two isolates showed a 27 kDa protein fraction related to the Bt subspecies israelensis cytolytic toxin (cyt) gene. One 130 kDa protein, possibly related to the Bt crystal inclusions (cry1) gene, was identified in the other two isolates, which were more toxic for lepidoptera; another isolate presented a protein of 100 kDa. Some new local Bt isolates had similar LC50 probit values to the reference strains.
Assuntos
Bacillus thuringiensis/patogenicidade , Culex/microbiologia , Lepidópteros/microbiologia , Controle Biológico de Vetores/métodos , Animais , Bacillus thuringiensis/química , Bacillus thuringiensis/isolamento & purificação , Eletroforese em Gel de Poliacrilamida , Larva/microbiologia , Microbiologia do SoloRESUMO
Fragments of ileum from 663 pigs were collected in abattoirs, prepared with the use of standard histological methods and stained with a novel sensitive histochemical method for the detection of porcine proliferative enteropathy. The method is a combination of the following 3 well-known methods, the Warthin-Starry method, alcian blue and hematoxylin-eosin. In 11 cases, mucus-producing cells were completely absent, severe adenomatous proliferation was observed and intracellular bacteria were found in enterocytes. Disappearance of goblet cells and the presence of adenomatous proliferation without any detectable intracellular bacteria were observed in 16 cases. In the remaining 636 cases, histological changes and intracellular bacteria were not found. When comparing the conventional Warthin-Starry method with the modified staining method presented here, the same 16 cases were found. However, the method presented here enables examination of large numbers of sections in a relatively short period of time.