Cecropin A (CA) fungicidal properties were explored. Nongerminated and germinated Aspergillus spp. and Fusarium spp. conidia were treated with CA. CA achieved complete lethality at < or = 25 microM (99 micrograms/ml) for germinating, but not nongerminating, conidia of Aspergillus spp. CA achieved total lethality for nongerminated and germinating conidia of Fusarium spp at 1.5 microM (6 micrograms/ml). MIC and minimal lethal concentration assays in buffered RPMI medium gave similar results.
Cleavage of the lactone ring of aflatoxin B1 results in a nonfluorescent compound that has greatly reduced biological activity. Mutagenicity, as measured by the Ames test, is reduced 450-fold compared to that of B1, and toxicity, as measured by the chick embryo test, is reduced 18-fold.
During a 2-year study, samples of various types of soils were collected from 115 fields that had not previously been tested with Bacillus thuringiensis and which were remote from any large-scale aggregations of lepidopterous insects in rearing or grain-storage areas. An average of about 400 isolates were examined from each soil, and, of 46 373 isolates examined, only 250 (0.5%) were identified as B. thuringiensis. While it was almost impossible to insure that a field had never been treated with B. thuringiensis or that drift from some nearby application had not reached the field, it is noteworthy that of the 250 isolates, 156 (62.4%) were not var. kurstaki, the only variety that has been used commercially in the United States in about 10 years. This is a strong indication that the B. thuringiensis isolates observed were present naturally. To verify the procedures used, samples were taken from two adjacent experimental plots which had been treated about 12 months previously with formulations of var. kurstaki and var. galleriae, respectively. With practically no exception, the variety recovered from each plot was the variety applied, indicating that the varietal status of B. thuringiensis is stable in the soil.
Nanocrystalline cellulose is an amphiphilic, high surface area material that can be easily functionalized and is biocompatible and eco-friendly. It has been used singularly and in combination with other nanomaterials to optimize biosensor design. The attachment of peptides and proteins to nanocrystalline cellulose and their proven retention of activity provide a route to bioactive conjugates useful in designs for point of care biosensors. Elastase is a biomarker for a number of inflammatory diseases including chronic wounds, and its rapid sensitive detection with a facile approach to sensing is of interest. An increased interest in the use of elastase sensors for point of care diagnosis is resulting in a variety of approaches to elsastase sensors utilizing different detection technologies. Here elastase substrate peptide-celluose conjugates synthesized as colorimetric and fluorescent sensors on cotton cellulose nanocrystals are compared. The structure of the sensor peptide-nanocellulose crystals when modeled with computational crystal structure parameters demonstrates the spatio-stoichiometric features of the nanocrystalline surface that allows ligand to active site protease interacttion. An understanding of the structure/function relations of enzyme and conjugate substrate of the peptides covalently attached to nancellulose has implications for enhancing the biomolecular transducer. The potential applications of both fluorescent and colorimetric detection to markers like elastase using peptide cotton cellulose nanocrystals as a transducer surface to model point of care biosensors for protease detection are discussed.
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