Intraspecific transduction in Staphylococcus epidermidis and interspecific transduction between Staphylococcus aureus and Staphylococcus epidermidis

Phages were isolated from Staphylococcus epidermidis after exposure of cultures to mitomycin C. Using certain of these phages, genes controlling resistance to novobiocin, streptomycin, and erythromycin and genes involved in the synthesis of adenine and riboflavin were transferred from donor to recipient strains of S. epidermidis. Interspecific transduction of the Novr marker was accomplished between S. epidermidis and S. aureus. Attempts to transfer penicillin resistance were not successful.

Factors affecting deoxycholate inactivation and Mg++ reactivation of Bacillus megaterium KM membrane nicotinamide adenine dinucleotide (reduced form) oxidase

Decay of the reduced nicotinamide adenine dinucleotide oxidase of Bacillus megaterium KM membranes was prevented by storage in 10% (v/v) glycerol or 0.4% bovine serum albumin. Differential rates of solubilization of components of the oxidase system by 0.4% deoxycholate was demonstrable at 4 C. The amount of Mg(++) necessary for maximal oxidase reactivation increased with increasing amounts of deoxycholate-inactivated oxidase. Mg(++) activation of deoxycholate-inactivated oxidase was partially temperature-dependent. Maximal activation was observed at 37 C, but only partial activation took place at 4 C. A small amount of deoxycholate was required for Mg(++) activation of deoxycholate-inactivated oxidase. Two pH optima were found for Mg(++) activation of deoxycholate-inactivated oxidase, pH 5.3 and 7.3. Significant amounts of activation of the inactive oxidase occurred in the absence of Mg(++) with an optimum at pH 5.0, with essentially no Mg(++)-independent activation demonstrable at pH 7.0.

Masking of Bacillus megaterium KM membrane reduced nicotinamide adenine dinucleotide oxidase and solubilization studies

Solubilization of a reduced nicotinamide adenine dinucleotide (NADH)-2,6 dichlorophenol indophenol (DCIP) oxidoreductase associated with the membrane NADH oxidase system of Bacillus megaterium KM was effected by treatment with 0.2% sodium deoxycholate, 8 m urea, or buffer (pH 9.0) in the presence of ethyl-enediaminetetraacetate. These treatments inactivated membrane NADH oxidase. It was found that membrane NADH oxidase and NADH-DCIP oxidoreductase were masked in membranes. Several procedures, including brief sonic oscillation, treatment with 0.05% deoxycholate, prolonged stirring at 4 C with 10% glycerol, and washing in the absence of Mg(2+), unmasked the oxidase and oxidoreductase activities. It was necessary to study the masking and unmasking of these activities to quantitate adequately the effects of solubilization procedures. Further information on the localization of oxidase and oxidoreductase in subcellular fractions and the effects of electron transport inhibitors on NADH oxidation was also obtained.

Divalent cation activation of deoxycholate-solubilized and -inactivated membrane reduced nicotinamide adenine dinucleotide oxidase of Bacillus megaterium KM

After treating Bacillus megaterium KM membranes with 0.2% sodium deoxycholate, most of the membrane reduced nicotinamide adenine dinucleotide (NADH) oxidase was inactivated, and all of the membrane NADH-2,6 dichlorophenol indophenol oxidoreductase was solubilized. Dilution of the deoxycholate-treated membranes in the presence of divalent cations restored almost all of the original membrane NADH oxidase. The effectiveness of the divalent cation activation decreased in the order Ba(2+) > Ca(2+) > Mg(2+) > Mn(2+). After centrifugation, the deoxycholate-treated membranes at 100,000 x g for 1 hr, all of the NADH oxidase that was activated by a divalent cation was soluble. Cation-activated oxidase, however, was insoluble. The results show that 0.2% deoxycholate at least partially solubilizes the total electron chain from NADH to O(2) in an inactive from which can be reactivated by divalent cations with the formation of active, insoluble NADH oxidase.

Hydrogenase measurement with photochemically reduced methyl viologen

Methyl viologen was reduced photochemically in the presence of proflavine and ethylenediaminetetraacetic acid. The reduced methyl viologen was oxidized by hydrogenase from Vibrio succinogenes. H(2) and oxidized methyl viologen were the products. Hydrogenase activity was determined by spectrophotometric measurement of the disappearance of reduced methyl viologen at 600 nm. The extinction coefficient of reduced methyl viologen was determined and is 8.25 mm(-1) x cm(-1) at 600 nm. Optimal conditions for assaying V. succinogenes hydrogenase were developed. Extracts of Escherichia coli and Desulfovibrio desulfuricans catalyzed reduced methyl viologen oxidation in the assay system, whereas Azotobacter vinelandii extracts were inactive.

An attempt to modify the rewarding characteristics of hypothalamic stimulation

7 rats with chronically implanted electrodes in the lateral hypothalamus were allowed to self-stimulate in a Skinner box until they stabilized. Ss were then given avoidance training in a jumping apparatus. The discriminative stimulus for avoidance was reinforcing brain stimulation. All Ss were returned to the Skinner box after avoidance training and were allowed to self-stimulate. No differences were found in lever-pressing as the result of previous avoidance training.