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D J Kushner

Publications and source records attributed to D J Kushner.

At least 37 records · Page 2Linked to original sources
PubMed1982

Polar lipids in phototrophic bacteria of the Rhodospirillaceae and Chromatiaceae families.

The polar lipids of photosynthetic purple bacteria of the genera Chromatium, Thiocapsa, Thiocystis, Ectothiorhodospira, Rhodopseudomonas, Rhodospirillum, and Rhodomicrobium were analyzed. Characteristic compositions of the polar lipids were found for most of the Rhodospirillaceae and Chromatiaceae species. Phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin were the major phospholipids in most species. Phosphatidylcholine was present as a major component in all species of the genus Ectothiorhodospira, but was not detected in the remaining Chromatiaceae. It was also present in most of the Rhodospirillaceae species. No glycolipids were found in any of the Ectothiorhodospira species. In the Rhodospirillaceae, the glycolipids mono- and digalactosyl diglycerides were generally absent. Sulfoquinovosyl diglyceride was present in significant amounts in at least three species of the Rhodospirillaceae and may have been present in most of them, but only in traces. All of the Chromatiaceae species contained several glycolipids, one of which was similar to monogalactosyl diglyceride. Ornithine lipids were found in large amounts in most Rhodospirillaceae, but were absent in Ectothiorhodospira and in the other Chromatiaceae. The species examined could be divided into three groups on the basis of their lipid composition: (i) the genus Ectothiorhodospira; (ii) the remaining Chromatiaceae; and (iii) the Rhodospirillaceae. The data presented are compared with those available in the literature, and differences from other phototrophic organisms are discussed.

Chromatiaceae↗
PubMed1981

Purification and properties of 5'-nucleotidase from the membrane of Vibrio costicola, a moderately halophilic bacterium.

Two different Mg2+-dependent adenosine 5'-triphosphate-hydrolyzing activities were detected in membranes of Vibrio costicola, a novel 5'-nucleotidase and an N,N'-dicyclohexylcarbodiimide-sensitive adenosine triphosphatase. The former and the latter had different requirements for Mg2+ and were selectively assayed in the membranes by using, respectively, 20 and 2 mM Mg2+. The two enzymes were extracted with a combination of Triton X-100 and octylglucoside, separated on a diethylaminoethyl cellulose column, and purified on glycerol gradients. The purified 5'-nucleotidase consisted of one major polypeptide of 70,000 daltons when analyzed on polyacrylamide gels in the presence of sodium dodecyl sulfate. The purified 5'-nucleotidase was similar in substrate specificities, divalent cation specificities, and pH profiles to the membrane-bound N,N'-dicyclohexylcarbodiimide-insensitive nucleotide-phosphohydrolyzing activity. The enzyme hydrolyzed nucleoside 5'-tri, 5'-di, and 5'-monophosphates at comparable rates. Inorganic pyrophosphate, p-nitrophenyl phosphate, glucose 6-phosphate, beta-glycerophosphate, adenosine 5'-diphosphate glucose, adenosine 3'-monophosphate, and cyclic adenosine 3',5'-monophosphate were not hydrolyzed, either im membranes or by the purified 5'-nucleotides. Actions of NaCl and KCl on the activity of the 5'-nucleotidase were studied. The enzyme was activated by both NaCl and KCl; the activation profiles however, were different for the membrane-bound and purified 5'-nucleotidase. The purified enzyme, unlike the membrane-bound enzyme, was markedly stimulated by high concentrations of NaCl (up to 3 M).

5'-Nucleotidase↗
PubMed1980

Comparison of nine brands of membrane filter and the most-probable-number methods for total coliform enumeration in sewage-contaminated drinking water.

Nine different brands of membrane filter were compared in the membrane filtration (MF) method, and those with the highest yields were compared against the most-probable-number (MPN) multiple-tube method for total coliform enumeration in simulated sewage-contaminated tap water. The water was chlorinated for 30 min to subject the organisms to stresses similar to those encountered during treatment and distribution of drinking water. Significant differences were observed among membranes in four of the six experiments, with two- to four-times-higher recoveries between the membranes at each extreme of recovery. When results from the membranes with the highest total coliform recovery rate were compared with the MPN results, the MF results were found significantly higher in one experiment and equivalent to the MPN results in the other five experiments. A comparison was made of the species enumerated by these methods; in general the two methods enumerated a similar spectrum of organisms, with some indication that the MF method was subject to greater interference by Aeromonas.

Chlorine↗
PubMed1980

Strategies of response to copper, cadmium, and lead by a blue-green and a green alga.

The toxic metal ions Cu2+, Cd2+, and Pb2+ inhibited growth of the green alga Ankistrodesmus braunii and the blue-green alga (Cyanobacterium) Anabaena, strain 7120. Some concentrations of Cu lysed Anabaena 7120 at early, but not late, stages of growth. The other metals inhibited growth without causing lysis. Adding the chelating agent nitrilotriacetic acid (NTA) did not reduce, and in some cases increased, metal toxicity to Anabaena 7120. This suggests that these metals do not act on this alga only in the ionic form. When Anabaena 7120 grew in a sublethal concentrations of Cu(NO3)2 (10(-5)M) most of the Cu was found outside the cell, in nonionic form. About half the Cd was found to be cell associated when these algae grew in the presence of 10(-5)M Cd(NO3)2. Ankistrodesmus braunii bound substantial amounts of both Cd and Cu when growing in their presence. At certain Cu levels, the amount bound per cell remained virtually constant during growth. In Cd, the amount bound per cell was highest at the beginning of growth and then fell. Cell-associated metals were found in both wall plus membrane and cytoplasmic fractions of A. braunii after mechanical lysis. When these algae grew over dialysis sacs containing sediment loaded with Cd or Cu, substantial amounts of these metals left the sediment and entered the algal cultures. They were found both cell associated and in the culture medium of A. braunii. In cultures of Anabaena 7120, Cd removed from the sediment was found in both cells and culture medium, but Cu was found almost entirely in the culture medium. The effects that bloom of such algae might have on the mobilization of these metals from sediments in natural waters are discussed.

Cadmium↗
PubMed1979

Inhibition of the growth of Neisseria meningitidis by reduced ferritin and other iron-binding agents.

Serogroups of N. meningitidis were characterized as virulent or avirulent according to their capacity to establish meningococcal infection in mice. An agar plate diffusion technique demonstrated that iron had a definite growth-supporting role for both of these meningococcal types. The avirulent strains could use ionic or chelated iron as well as the virulent strains. Iron-reversible growth inhibition occurred to the same extent for both bacterial types in the presence of the synthetic iron-chelating agents Desferal and ethylenediamine-di-orthohydroxy phenylacetic acid. A difference in response was demonstrated for these bacterial types when grown in the presence of various iron-binding proteins from animal body fluids and tissues. The growth of the avirulent strain was inhibited to a greater degree by egg white conalbumin. The humoral iron-binding protein transferrin showed a significant inhibitory capacity only when used in conjunction with bicarbonate. Under conditions of increased iron saturation of this protein, the avirulent strain was inhibited to the furthest extent. In the presence of ferritin, the cellular iron-binding protein, which had been reduced, inhibition of the growth of either strain type did not occur on iron-poor media (less than 5 micrograms/100 ml). However, with the incorporation of iron into the media, the inhibitory effect of the protein became evident. As the concentration of iron increased, the inhibition increased to a certain level and subsequently declined. A substantial difference in the ability of the avirulent type to grow in the presence of reduced horse spleen ferritin was observed. For this microorganism, a correlation appears to exist between the capacity to grow by utilizing the available iron in the presence of reduced ferritin and the ability to establish infection. The host protein ferritin, in the reduced state, apart from simply being a storage protein for iron, can prevent the growth of a procaryotic organism. Our experiments suggest a role for ferritin in the prevention of emningococcal disease. A cehmotherapeutic potential for Desferal is also implied.

Conalbumin↗
PubMed1978

Stimulation of lipase production during bacterial growth on alkanes.

Acinetobacter lwoffi strain O(16), a facultative psychrophile, can grow on crude oil, hexadecane, octadecane, and most alkanes when tested at 20 but not at 30 degrees C. Growth occurred on a few alkanes at 30 degrees C but after a longer lag than at 20 degrees C. Cells grown on alkanes as sole carbon sources had high levels of cell-bound lipase. In contrast, previous work has shown that those grown on complex medium produced cell-free lipase and those grown on defined medium without alkanes produced little or no lipase. Low concentrations of the detergent Triton X-100 caused the liberation of most of the lipase activity of alkane-grown cells and increased total lipase activity. When ethanol and hexadecane were both present in a mineral medium, diauxic growth occurred; until the ethanol was completely used up, hexadecane was not utilized, and the lipase activity was very low. When growth on hexadecane began, lipase activity increased, reaching a level 50- to 100-fold higher than that of cells growing on ethanol. A similar pattern of lipase formation and hexadecane utilization was observed with Pseudomonas aeruginosa. Whenever A. lwoffi and other bacteria degraded alkanes they exhibited substantial lipase activity. Not all bacteria that produced lipase, however, could attack alkanes. Bacteria that could not produce lipase did not attack alkanes. The results suggest that a correlation may exist between lipase formation and alkane utilization.

Acinetobacter↗
PubMed1977

Penicillinase (beta-lactamase) formation by blue-green algae.

Beta-Lactamase (penicillinase) activity was found in a number of strains of blue-green algea. In some cases, this enzyme permitted algae to overcome the inhibitory effects of penicillin. Production and localization of beta-lactamase were studied in a unicellular species, Coccochloris elabens (strain 7003), and in a filamentous, nitrogen-fixing Anabaena species (strain 7120). When cells were grown in a neutral medium with NaNO3 as N source, the pH rose during growth; at a pH of about 10, most of the enzyme was expressed equally well in intact or disrupted cells. If the pH was kept near neutrality during growth by gassing with CO2 in N2 or by growth under conditions of N2 fixation, the enzyme remained cell-bound and cryptic for most of the growth phase, being measurable only after cells were disrupted. The enzymes from strains 7003 and 7120 had greater activity on benzyl penicillin and other penicillins than on cephalosporins. Some differences were observed in the "substrate proliles" of penicillinases from the two strains against different penicillins.

Cyanobacteria↗
PubMed1977

Cell-bound cations of the moderately halophilic bacterium Vibrio costicola.

Over most of the range of salt concentrations in which the moderately halophilic bacterium Vibrio costicola could grow, the sum of the cell-associated Na+ + K+ ions was at least as high as in the external medium. This is in contrast to other moderate halophiles, which have substantially lower internal than external salt concentrations for most of their growth range. The relative amounts of Na+ and K+ in V. costicola varied with environmental conditions. The K+/Na+ ratio fell during anaerobic incubation or when cells were poisoned. As Na+ ions left the cells, K+ ions entered. However, movement of these ions was not tightly coupled, since K+ content of cells could increase without a corresponding decrease in Na+ content. The Mg2+ contents of cells varied little with environmental conditions.

Culture Media↗
PubMed1977

Effects of temperature on the macromolecular composition and find structure of psychrophilic Arthrobacter species.

A facultatively psychrophilic bacterium, Arthrobacter SI 55, grows at 20 degrees C, but growth, as measured by increase of viable cell count, is inhibited at 32 degrees C. Corresponding temperatures for an obligate psychrophile, Arthrobacter glacialis SI 137, are 10 degrees C and 19-20 degrees C. At the higher temperatures for each organism increases of cell mass, as measured by turbidity and of DNA, RNA, and protein, were not inhibited. At the upper temperatures, fewer septa were formed in Arthrobacter SI 55, and cells appeared as distorted filaments with irregular brancehs. Arthrobacter glacilis grew as single cells at the lower temperature, but as clumps of coccoid cells with well marked septa at the higher temperature. It appears that in Arthrobacter SI 55 septum formation may be inhibited at the higher temperature. In contrast, in A. glacialis septation occurs but the cells do not separate.

Arthrobacter↗
PubMed1977

The effect of proflavine on pyruvate kinase I of Escherichia coli B.

Proflavine (PF) inhibited glucose use in sensitive but not resistant Escherichia coli B. Glucose transport (as measured by alpha-methylglucoside accumulation) was only partly inhibited by PF concentration that completely blocked glucose use. Fructose 1,6-diphosphate-(FDP)-regulated pyruvate kinase (PK1) (EC 2.7.1.40), the only glycolytic enzyme affected by PF, was completely inhibited by a dye concentration of 0.8 mM. The inhibition curve for PF was sigmoidal, suggesting that PF was acting as an allosteric inhibitor. PF increased the K 1/2 for phosphoenolpyruvate (PEP) and lowered the V; however, it had no effect on the Hill number for PEP. PF inhibition was partially reversed by FDP but not by cyclic AMP, AMP, ATP, fuctose 6-phosphate, or dithiothreitol. Studies with a variety of acridines indicated that those substituted at the 3-position are the most effective inhibitors and also that hydrophobic interactions may be involved in PF inhibition of PK I. PK I for E. coli B/Pr was also strongly inhibited by PF, indicating that PF resistance does not lie at the level of this enzyme. Ribose-5-phosphate-regulated pyruvate kinase (EC 2.7.1.40) was much less sensitive that PK I to the inhibitory effects of PF. A role for PF as a molecular probe for PK I has been proposed.

Acridines↗
PubMed1976

Tubular structures of Vibrio psychroerythrus.

The marine bacterium Vibrio psychoerythrus, an obligate psychrophile, contains uniformly dense rod-shaped organelles 10-15 nm wide and up to 1.3 mum long. These structures were frequently seen crossing the septum of dividing cells.

Cell Division↗
PubMed1976

Cellulase induction and the use of cellulose as a preferred growth substrate by Cellvibrio gilvus.

Cellvibrio gilvus produced cellulase when grown in the presence of cellulose or carboxymethyl cellulose (CMC) but not when grown in the presence of glucose or cellobiose. This was so whether or not these compounds were the sole carbon sources present. Repeated addition of small amounts of glucose prevented cellulase formation in the presence of cellulose. It is concluded that cellulose and CMC induce cellulase formation and glucose and cellobiose repressit. Cellulose stimulated growth when added to organic media. Physical contact between cells and cellulose fibres was necessary for both cellulase induction and growth stimulation. If cellulase induction was prevented by glucose, cellulose did not stimulate growth.

Bacterial Proteins↗