Sensitivity of Partially Purified Ice Nucleation Activity of Fusarium acuminatum SRSF 616

Factors that affect bacterial ice nucleation, including growth medium, growth phase, nutrient deprivation, and cold-temperature exposure, were investigated in the ice nucleation active (INA) fungus Fusarium acuminatum SRSF 616. Ice nucleation activity remained relatively constant throughout the growth cycle, and the cell-free culture supernatant consistently displayed higher ice nucleation activity than the hyphal pellet. Although nutrient starvation and low-temperature exposure enhance bacterial ice nucleation activity, reducing the concentration of C, N, or P in synthetischer nährstoffarmer broth (SNB) did not increase fungal ice nucleation activity, nor did exposure to 4°C or 15°C. From the SNB supernatant, selected INA chromatography fractions were obtained that demonstrated increased sensitivity to proteinase K and heat compared with culture supernatant. We propose that partial purification of the fungal ice nuclei resulted in removal of low-molecular-weight stabilizing factors.     

Genetic variation in Beauveria bassiana populations associated with the darkling beetle, Alphitobius diaperinus

A study was conducted to assess genetic variation within and among populations of Beauveria bassiana (Deuteromycotina: Hyphomycetes) associated with the darkling beetle, Alphitobius diaperinus (Coleoptera: Tenebrionidae), using RAPD markers. A hierarchical collection of samples (strains from the same insect specimen, from insects from the same location, and from insects from different locations) was obtained from infected beetles from North Carolina (NC) and West Virginia (WV), USA. Ten primers resolved 81 strains into 80 distinct multiband phenotypes reflecting the substantial amount of variation that was present. Variation present within populations was evident not only in the separation of each strain as a distinct multiband phenotype but also in the separation of strains within a population into separate clusters. Among populations, a group sharing more than 89% similarity was observed among all the strains from Martin Co. and Greene Co., NC and 61% of the strains collected from WV. Some genetic differentiation was present among the other populations but the separation was not distinct with a few strains from some populations showing greater affinity to strains from other collection sites.     

Biology of two members of the Euwallacea fornicatus species complex (Coleoptera: Curculionidae: Scolytinae), recently invasive in the U.S.A., reared on an ambrosia beetle artificial diet

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An optimized protocol for metabolome analysis in yeast using direct infusion electrospray mass spectrometry

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Identification of ice-nucleating active Pseudomonas fluorescens strains for biological control of overwintering Colorado potato beetles (Coleoptera: Chrysomelidae)

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