Article Abstract:
Characterization of spores from Bacillus thuringiensis Cry+ strains by fluorescent labeling studies revealed a 65-kDa activated Cry 1Ac toxin. Removal of the exosporia by heat treatment allowed Cry+ spores to bind the toxin receptor from insect gut brush border membranes and increased germination rates threefold. The spores did not exhibit this ability when the Cry toxins were in the soil, suggesting that the exosporium prevents binding to the insect receptors. A model describing the surface localization of these toxins on spores is discussed.
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Article Abstract:
The resistance of certain strains of Bacillus subtilis spores to ultraviolet radiation and dry heat appears to result from the presence of a DNA- binding protein, while resistance to hydrogen peroxide and moist heat seems to decrease with higher core water content. Researchers studied the resistance to these elements of wild type or mutated spores that had normal or elevated core water levels, and the absence or presence of two small, acid-soluble proteins. These proteins seemed to protect spore DNA by binding to it.
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Article Abstract:
Models of spore resistance mechanisms are discussed, focusing on the endospores of Bacillus spp. Spores are one of the hardiest forms of life on Earth and can survive both terrestrial and extra-terrestrial environmental extremes.
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