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The physiological consequences of trichloroethylene (TCE) transformation by three butane oxidizers were examined. Pseudomonas butanovora, Mycobacterium vaccae, and Nocardioides sp. CF8 utilize distinctly different butane monooxygenases (BMOs) to initiate degradation of the recalcitrant TCE molecule. Although the primary toxic event resulting from TCE cometabolism by these three strains was loss of BMO activity, species differences were observed. P. butanovora and Nocardioides sp. CF8 maintained only 4% residual BMO activity following exposure to 165 μM TCE for 90 min and 180 min, respectively. In contrast, M. vaccae maintained 34% residual activity even after exposure to 165 μM TCE for 300 min. Culture viability was reduced 83% in P. butanovora, but was unaffected in the other two species. Transformation of 530 nmol of TCE by P. butanovora (1.0 mg total protein) did not affect the viability of BMO-deficient P. butanovora cells, whereas transformation of 482 nmol of TCE by toluene-grown Burkholderia cepacia G4 caused 87% of BMO-deficient P. butanovora cells to lose viability. Together, these results contrast with those previously reported for other bacteria carrying out TCE cometabolism and demonstrate the range of cellular toxicities associated with TCE cometabolism. [ABSTRACT FROM AUTHOR]

The article focuses on issues regarding sociology of education in the U.S. According to the author, radical education historians tend to focus on conflicts over the structure of the educational system. On the other hand, Max Weber suggested that a critical element of the power of dominant groups resides in their capacity to impose educational and cultural ideals on school. Furthermore, the absence in conflict theory of an analysis of educational system has proved damaging to the emergence of a radical theory of educational politics.

The blooming cosmopolitan coccolithophore Emiliania huxleyi and its viruses (EhVs) are a model for density-dependent virulent dynamics. EhVs commonly exhibit rapid viral reproduction and drive host death in high-density laboratory cultures and mesocosms that simulate blooms. Here we show that this system exhibits physiology-dependent temperate dynamics at environmentally relevant E. huxleyi host densities rather than virulent dynamics, with viruses switching from a long-term non-lethal temperate phase in healthy hosts to a lethal lytic stage as host cells become physiologically stressed. Using this system as a model for temperate infection dynamics, we present a template to diagnose temperate infection in other virus–host systems by integrating experimental, theoretical, and environmental approaches. Finding temperate dynamics in such an established virulent host–virus model system indicates that temperateness may be more pervasive than previously considered, and that the role of viruses in bloom formation and decline may be governed by host physiology rather than by host–virus densities. The blooming alga Emiliania huxleyi and its viruses are a model for density-dependent virulent dynamics. However, Knowles et al. show that this host–virus system exhibits temperate dynamics at natural host densities, in a manner dependent on host physiology. [ABSTRACT FROM AUTHOR]