Properties of somatic cell hybrids between mouse cells and simian virus 40-transformed rat cells

Hybrids between mouse cells and simian virus 40 (SV40)-transformed rat cells were made, and their properties and chromosome constitution were investigated over many generations. Their hybrid nature was confirmed by enzyme studies. During a period of 1 year a loss of 10 to 20% of the total number of chromosomes was observed. The SV40 tumor antigen was present and remained present in the hybrids. The parental and hybrid cells were studied for agglutination with concanavalin A, for growth in soft agar, and for serum requirement. These growth and surface characteristics of the transformed cells appeared in the hybrids.

Mode of action of oxathiin systemic fungicides. V. Effect on electron transport system of Ustilago maydis and Saccharomyces cerevisiae

The systemic fungicide carboxin (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide) at 100 mum inhibited succinate cytochrome c reductase in mitochondria from Ustilago maydis and Saccharomyces cerevisiae. It did not have any effect on reduced nicotinamide adenine dinucleotide (NADH) cytochrome c reductase. Succinate coenzyme Q reductase was also inhibited, but NADH coenzyme Q reductase was not. When dichlorophenolindophenol (DCIP) was used as the terminal acceptor of electrons from the oxidation of succinate, carboxin was very effective in inhibiting succinate-DCIP reductase. Carboxin was inhibitory to succinic dehydrogenase assayed with phenazine methosulfate plus DCIP when intact mitochondria were used as the enzyme source but not when solubilized enzyme was used. The main site of action of carboxin, therefore, appears to lie between succinate and coenzyme Q. The dioxide analogue of carboxin was also effective in inhibiting succinate-cytochrome c reductase, succinate-coenzyme Q reductase, or succinate-DCIP reductase, whereas the monoxide analogue was less effective in inhibiting these enzymes.

The uptake of ascorbic acid by the tissues of ascorbic acid-deficient guinea-pigs

The uptake of ascorbic acid by the organs of near-scorbutic guinea-pigs was examined. Tissue saturation was achieved in the liver, spleen, heart and adrenals 24 h after the administration of 1 % ascorbic acid in the drinking water; saturation of the eye lens, testes and brain was less rapid. A transient ‘supersaturation’ of 5 days’ duration occurred in the liver, spleen and heart. It is suggested that supersaturation, if it occurs in man, could effect a partial invalidation of the classical ‘saturation test’ for ascorbic acid insufficiency.

Chemical and physical characteristics of the deoxycholate-soluble and magnesium-reaggregated membrane nicotinamide adenine dinucleotide (reduced form) oxidase of Bacillus megaterium

The inactive components of the nicotinamide adenine dinucleotide (reduced form) (NADH) oxidase present in the 0.4% deoxycholate-soluble fraction obtained from Bacillus megaterium KM membranes were reaggregated into active NADH oxidase by dilution in the presence of Mg(2+). The reaggregated oxidase was different from the original membrane with respect to sedimentation behavior in a sucrose gradient and morphological appearance. The deoxycholate-insoluble portion of the membrane had membrane-like structure whereas the reaggregated oxidase appeared to be a filamentous aggregate of small particles. The reaggregated oxidase and the deoxycholate-insoluble membrane residue were similar to the original membrane with respect to total protein and total lipid content. The inactive components of the NADH oxidase system exist in deoxycholate as two molecular species which were separable by sucrose density gradient centrifugation or gel filtration in deoxycholate-containing solutions. Both components and dilution in the presence of Mg(2+) were necessary for restoration of oxidase activity. The smaller-molecular-weight component contained all of the NADH-2,6-dichlorophenolindophenol oxidoreductase activity of the original membrane.

Separation of the primary dehydrogenase from the cytochromes of the nicotinamide adenine dinucleotide (reduced form) oxidase of Bacillus megaterium

A selective extraction procedure was developed for sequentially extracting a fraction containing the primary dehydrogenase and a fraction containing the cytochromes of the nicotinamide adenine dinucleotide (reduced form) (NADH) oxidase of Bacillus megaterium KM membranes. The primary dehydrogenase (NADH-2,6-dichlorophenolindophenol oxidoreductase) activity was extracted from sonically treated membranes with 0.4% sodium deoxycholate for 30 min at 4 C. The insoluble residue was extracted with 0.4% sodium deoxycholate in 1 m KCl for 30 min at 25 C. A combination of the two extracts and dilution in Mg(2+) gave good recovery of the original membrane NADH oxidase activity. The primary dehydrogenase fraction contained 41% of the membrane protein, no cytochromes, flavine adenine dinucleotide as the sole acid-extractable flavine, and most of the membrane ribonucleic acid (RNA). The cytochrome-containing fraction had 16% of the membrane protein, 61% of the membrane cytochrome with the same relative amounts of cytochromes a and b as the original membrane, no acid-extractable flavine, little RNA, and no oxidoreductase activity. The oxidoreductase fraction remained soluble after removal of deoxycholate whereas the cytochrome fraction became insoluble after removal of deoxycholate-KCl, but the precipitated fraction could be redissolved in 0.4% sodium deoxycholate. Treatment of both fractions with ribonuclease to destroy all of the RNA present did not affect the ability of the fractions to recombine into a functional oxidase unit. Treatment of either fraction with phospholipase A prevented restoration of a functional oxidase when the oxidoreductase and cytochrome fractions were treated in solution, but no affect on restoration of oxidase was observed when the phospholipase A treatment was carried out with the soluble oxidoreductase fraction and the insoluble cytochrome fraction.