Toxicity of 2-mercaptobenzothiazole towards bacterial growth and respiration.

Active sludge systems containing benzothiazoles may be intoxicated by 2-mercaptobenzothiazole (MBT). This toxicity towards several bacteria is now confirmed and is situated at around 100 mg MBT l-1. Octanol-water partition coefficients indicated that MBT might interact with membrane-bound systems. This was confirmed through experiments showing that bacterial cell respiration was inhibited using lactate or succinate as substrates. Using these substrates and also NADH, it was found that their oxidation was also inhibited using isolated membrane fragments of Escherichia coli and Paracoccus denitrificans. Methylene blue reduction was also found to be inhibited. The oxidation of ascorbate was not inhibited in P. denitrificans. From these results it is suggested that MBT might interact with the respiratory chain at the level of flavoproteins or quinones and Fe-S clusters.

Nerve growth factor stimulates rapid metabolic responses in PC12 cells.

Research into the effects of nerve growth factor (NGF) has involved study of either the signal transduction process or the morphological result of growth factor treatment (cell proliferation and/or differentiation). The Cytosensor Microphysiometer, a silicon-based biosensor system that allows the continuous and real-time monitoring of extracellular acidification rate changes of cells, was used to study the response of PC12 cells to NGF. Stimulation resulted in a rapid increase in the acidification rate of cells in a concentration-dependent fashion (0.1-200 ng/ml NGF; mean effective concentration value of 153 +/- 54 pM). Inhibition of the NGF receptor-linked protein tyrosine kinase by either genistein or K252a attenuated the acidification rate response to NGF. In addition, the acidification response to NGF could be modified by inhibiting Na+/H+ exchange and, separately, glycolysis. This implicates these processes in the metabolic response of PC12 cells to NGF stimulation.