Characterization of an endo-1,3-beta-D-glucanase produced during the interaction between the mycoparasite Stachybotrys elegans and its host Rhizoctonia solani.

The mycoparasite Stachybotrys elegans produces, in addition to a previously purified 94-kDa 1,3-beta-glucanase, at least three extracellular 1,3-beta-glucanases (75, 110, and 180 kDa) when grown on purified cell wall of Rhizoctonia solani. We purified to homogeneity an endo-1,3-beta-glucanase of 75 kDa which possesses a low K(m) value of 20 micrograms laminarin.mL-1 and is most active at pH 5.0 and 40 degrees C. Polyclonal antibodies raised against both the 75- and 94-kDa 1,3-beta-glucanases indicate that they are immunologically related but do not cross-react with the 110- and 180-kDa glucanases. Exposure of growing hyphal tips of R. solani to the pure 75-kDa 1,3-beta-glucanase caused them to swell and lyse. A transient increase of the 75-kDa 1,3-beta-glucanase with a concomitant decrease of the 94-kDa 1,3-beta-glucanase and the appearance of a 20-kDa protein were observed at the point of interaction between R. solani and Stachybotrys elegans on plates. Evidence suggesting a precursor-product relationship between the two 1,3-beta-glucanases is provided. Our results indicate that the 75-kDa 1,3-beta-glucanase may be involved in Stachybotrys elegans mycoparasitism.

Pleural mesothelioma and exposure to asbestos: evaluation from work histories and analysis of asbestos bodies in bronchoalveolar lavage fluid or lung tissue in 131 patients.

Exposure to asbestos was evaluated in 131 patients with pleural malignant mesothelioma in the Paris area between 1986 and 1992 using data from a detailed specific questionnaire and light microscopy analysis of the retention of asbestos bodies in bronchoalveolar lavage fluid or lung tissue. Probable or definite exposure to significant levels of asbestos dust was identified in only 48 (36.6%) subjects, and significant asbestos body counts (above 1 asbestos body/ml in bronchoalveolar lavage fluid or 1000 asbestos bodies/g of dry lung tissue) were found in only 45 (34.3%) subjects. Overall 50 subjects had experienced exposure to only low levels of asbestos or no exposure at all and showed no significant retention of asbestos bodies in the biological sample analysed. Previous studies have shown that light microscopy may be useful in the identification of subjects with previous exposure to asbestos. In this study, apart from cases with obvious exposure to asbestos, a large group of subjects seemed to have a history of exposure or lung retention of asbestos bodies suggestive of very low levels of cumulative exposure, similar to those described in the general population.

Effects of weight cycling in female rats.

Recent reports indicate that weight cycling (repeated periods of weight gain and loss) cause an organism to become an energy conserver, meaning that the organism gains weight more quickly and loses weight more slowly during subsequent weight cycles. The effects of weight cycling on rates of weight gain and loss, caloric efficiency, and ad lib wheel running were investigated with three groups of adult female rats: 1) cycling (cycled twice); 2) maturity control (cycled once); and 3) chow control (not cycled). The cycled group evidenced weight-gain periods of 36 and 21 days, respectively, and showed a significant increase in food efficiency during the second weight-gain period, relative to the first. There was no evidence that maturation was responsible for this phenomenon. Time required to lose weight and ad lib wheel running were not influenced by weight cycling. These findings suggest that weight cycling may make maintenance of normal weight more difficult and have implications for human weight-control programs.