bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracellular accumulation of L-glutamate in adenylyl cyclase deficient or cyclic AMP receptor protein deficient mutants of Escherichia coli
Authors: Leung Kwok-Luen , Yamazaki Hiroshi
Published: May 2010

An Escherichia coli cya mutant deficient in adenylyl cyclase and an E. coli crp mutant deficient in cyclic AMP receptor protein (CRP) accumulate substantial amounts of L-glutamate extracellularly when entering stationary phase of growth. The cya mutant grown in the presence of cyclic AMP accumulates little glutamate whereas the addition of cyclic AMP has no effect on glutamate accumulation in the crp mutant. It is proposed that an E. coli cell entering stationary phase requires a change in cell envelope structure which involves a cyclic AMP – CRP dependent process, and without this process the permeability of the cell membrane increases.
Evidence of thermonuclease production by Bacillus spp. and enterococci in naturally contaminated cheese
Authors: Bissonnette N. , Lachance R. A. , Goulet J. , Landgraf M. , Park C. E.
Published: May 2010

Of 105 thermonuclease-positive (TNase-positive) cheese samples comprising 13 types, 92 (87.6%) contained coagulase-positive staphylococci, whereas 9 (8.6%) contained microorganisms other than staphylococci as the major contaminants. Of the latter group, six samples contained Bacillus spp. comprising three species (B. cereus, B. licheniformis, and B. subtilis), and three contained mainly enterococci (Streptococcus faecalis), which were proven to be TNase producers. The organisms responsible for TNase production in the other four samples (3.8%) are not known, because isolates from these samples failed to produce the enzyme. Unlike staphylococcal TNase, a greater part of nonstaphylococcal TNase remains in the cheese homogenate after extraction of the enzyme at pH 3.8 instead of pH 4.5.
Clearance of inflammatory cells from the microcirculation of endotoxin-resistant C3H/HeJ mice
Authors: Walker Richard I. , Parker George A.
Published: May 2010

We studied the deposition of platelets and leukocytes in resistant (C3H/HeJ) and sensitive (C3Heb/FeJ) strains of mice challenged intraperitoneally with 1 mg of Salmonella typhi endotoxin, a dose lethal only for the sensitive strain. Comparable degrees of leukopenia and thrombocytopenia were evident at all time periods observed, but in contrast to sensitive mice, leukocytes and platelets were quickly cleared from the pulmonary microcirculation of resistant mice.
Cellulase production by Acetivibrio cellulolyticus
Authors: Saddler J. N. , Khan A. W.
Published: May 2010

Acetivibrio cellulolyticus, an isolate from an established sewage sludge culture, degraded cellulose powder, Avicel cellulose, and cellobiose. The organism showed maximum cellulose degradation in a medium containing 10 g/L of cellulose and it could also degrade cellulose in media containing up to 75 g/L of cellulose. During the exponential growth phase, large quantities of cellulolytic enzymes were found extracellularly whereas cellobiase activity was cell associated. The crude culture supernate contained endo- and exo-glucanase activities with a pH optimum at 5.0 and a temperature optimum at 50 °C. Maximum cellulase activities were detected in 2- to 3-day-old cultures grown on 1 g/L of cellulose. Cellulose concentration above 10 g/L caused the adsorption of these enzymes to the substrate and consequently lowered their detection in the supernate. The activities at 50 °C for endoglucanase, exoglucanase, and filter paper degrading ability, expressed as micrograms of glucose equivalents released per minute per milligram of protein culture supernate, were 510, 135, and 40 respectively.
The isolation, identification, and bioassay of the antifungal metabolites produced by Monocillium nordinii
Authors: Ayer William A. , Lee Sing Ping , Tsuneda Akihiko , Hiratsuka Yasuyuki
Published: May 2010

The metabolites produced when Monocillium nordinii (Bourchier) W. Gams, a destructive mycoparasite of pine stem rusts, is grown in liquid culture have been separated and identified. The metabolites include the known compound monorden (1) and five new substances, monocillin I (2), monocillin II (4), monocillin III (3), monocillin IV (5), and monocillin V (6). Structural assignments and chemical correlations of the five new compounds are reported and the absolute configuration of monorden is assigned. The antifungal spectra of the three major metabolites are reported. Monorden and monocillin I show pronounced activity against a wide variety of fungi, including Ceratocystis ulmi, the cause of Dutch elm disease. Extraction of the mycelium yielded averufin (13), along with a pigment C18H12O6, as yet unidentified.
Taxonomie numérique de 46 souches dénitrifiantes et mésophiles de Bacillus isolées à partir du sol par culture élective en présence de nitrite
Authors: Pichinoty F. , Garcia J. -L. , Mandel M.
Published: May 2010

Thirty-one denitrifying strains of Bacillus were isolated from soils of diverse origin by anaerobic enrichment culture at 32 °C in peptone medium containing nitrite. One strain was isolated when nitric oxide was provided as the sole terminal acceptor of electrons. All 32 belong to the second morphological group of the genus Bacillus. They denitrify NO3− and NO2−, are mesophilic, auxotrophic, and oxidase-positive. The numerical taxonomy of these 32 strains plus that of 15 strains isolated previously under the same conditions from tropical soils was done on the basis of 108 morphological, physiological, and biochemical characters. It reveals great heterogeneity. The DNA base composition, on the other hand, varies little from one strain to the other: the mean percentage of guanine + cytosineis40.5 ± 1.1. Two strains are related to Bacillus azotoformans. The other strains are clearly distinct from that species as well as from B. brevis. These results do not allow us to draw any final taxonomic conclusion. They are of some ecological interest because such bacteria seem to be ubiquitous in both temperate and tropical soils.
The effect of selected antineoplastic agents on the morphology of Candida albicans 5865
Authors: Land G. A. , Hulme K. L. , Chaffin W. L.
Published: May 2010

When examined in an amino acid supplemented inorganic salts – glucose medium, the morphological development of Candida albicans 5865 is inhibited or delayed by several drugs common to cancer chemotherapy protocols. Yeast phase growth is inhibited by actinomycin D (100 μg/mL), bleomycin (500 μg/mL), 5-fluorouracil (1000 μg/mL), and hydroxyurea (1000 μg/mL). Germ tube formation was also inhibited by actinomycin D (100 μg/mL), and vincristine (100 μg/mL), doxorubicin and bleomycin (each at 500 μg/mL), and 5-fluorouracil, cyclohexamide, hydroxyurea, and vinblastine at 1000 μg/mL, respectively. Following a 3-h exposure to the above drugs supplemented with sublethal concentrations of amphotericin B (AMB), yeast germination and chlamydospore formation were delayed 60–96 h. Culturing yeasts for 24 h in the presence of both AMB and actinomycin D resulted in a 90% loss in viability. Two antimetabolites not common to chemotherapeutic protocols also showed fungistatic and fungicidal activity. At 24 h, pentamidine isethionate (100 μg/mL) alone had a 90% kill rate which increased to greater than 99.99% when combined with AMB. A cyclic hydroxaneic acid, 7-chloro-3,4-dihydro-1-hydroxycarbostyril (7-Cl ADHC), demonstrated the lowest minimum germ tube inhibitory concentration (1 μg/mL). A 90% kill rate was obtained after culturing yeasts for 24 h in 7-Cl ADHC (100 μg/mL) supplemented with AMB.
Isolation and partial characterization of a lipopolysaccharide from phase II Coxiella burnetii
Authors: Baca Oswald G. , Martinez Irene L. , Aragón Adam S. , Klassen David
Published: May 2010

A lipopolysaccharide (LPS) was isolated by hot phenol–water extraction from phase II Coxiella burnetii. The LPS was isolated from organisms that had a history of 95 serial yolk sac passages and others that were cloned. The chemical composition of the LPS was partially determined and compared with that of LPS previously isolated from phase I organisms. Most of the sugars present in phase I LPS were detected in phase II LPS; however, there were some quantitative and qualitative differences. The fatty acid profiles of phase I and II LPS were identical. The amount of LPS extracted from phase II organisms was about [Formula: see text] the amount extracted from phase I C. burnetii. Limulus lysate gelation was observed with subnanogram amounts of both phase I and II LPS. In complement fixation tests, both LPSs reacted only with antisera containing antibodies versus phase I antigen. Ouchterlony immunodiffusion tests demonstrated immunological identity of the two LPSs.
Extracellular alkaline phosphatase from marine bacteria: purification and properties of extracellular phosphatase from a marine Pseudomonas sp.
Authors: Kobori Hiromi , Taga Nobuo
Published: May 2010

Extracellular alkaline phosphatase produced by a marine Pseudomonas was purified to electrophoretic homogeneity. The molecular weight of the enzyme was estimated to be 100 000. The enzyme had maximal activity at pH 11.5. The enzyme was completely inhibited by 1 mM EDTA. However, divalent cations reversed the enzyme inhibition and their order of effectiveness on the reaction was Zn2+ > Ca2+ > Mn2+ > Mg2+ > Sr2+ > Co2+. The enzyme activity was affected by the species of anion whose order of effectiveness was demonstrated to follow the lyotrophic series, Cl− > Br− > NO3−> ClO4− > SCN−. The activity of phosphatase was accelerated linearly by increased pressure until up to 1000 atm (1 atm = 101.325 kPa), and the enzyme activity at 1000 atm was 3.2 times higher than that at 1 atm.
Augmentation of clostridial partial haemolysis by some bacterial species
Authors: Smith John A. , Ngui-Yen John H.
Published: May 2010

One hundred and fifty-six strains of bacteria representing 12 genera were tested for augmented haemolysis in the presence of an alpha-toxin-producing strain of Clostridium perfringens. Synergistic haemolysis was produced by Aeromonas hydrophila, Acinetobacter calcoaceticus, Serratia marcescens. Staphylococcus aureus, and Staphylococcus epidermidis. The pattern of synergistic haemolysis by S. ureus differed from that observed with S. epidermidis, although they both correlated with delta-lysin production. In the case of A. hydrophila, A. calcoaceticus, and S. marcescens, lipase production correlated with augmented haemolysis. Synergistic haemolysis by all strains tested was inhibited by clostridial antitoxin.
Protein component of Pseudomonas aeruginosa slime glycolipoprotein in relation to laboratory-induced resistance to gentamicin
Authors: Lambris J. , Papavassiliou J. , Dimltracopoulos G.
Published: May 2010

Isoelectric focusing of the slime glycolipoprotein of a gentamicin-sensitive Pseudomonas aeruginosa strain showed the presence of four protein bands at a pH range of 5.45–6. Two additional protein bands at about pH 5.62 and pH 5.3 appeared in the slime glycolipoprotein of a laboratory-induced gentamicin-resistant variant.
Growth and survival of antibiotic-resistant denitrifier strains in soil
Authors: Smith M. Scott , Tiedje James M.
Published: May 2010

Using rifampicin-resistant denitrifier strains added to soil we found that some denitrifier strains were more competitive with indigenous soil microbes under aerobic conditions than under conditions which favored denitrification. Relative growth rates of denitrifiers in soil were unrelated to growth rates in pure cultures.
A new approach to the study of yeast ecology of natural substrates
Authors: Martini A. , Federici F. , Rosini G.
Published: May 2010

The yeast flora associated with the surface of various natural materials have been studied on the assumption that individual cells and microcolonies are strongly retained by gummy and mucous secretions. Preisolation treatments based on vigorous shaking, percolation with an excess of water, and the sonication of samples allowed the recovery of a much higher number of species than did traditional isolation procedures. Results confirmed that a sequence of aggressive and disruptive actions on samples, together with an enrichment culture, is necessary to obtain an exhaustive picture of the actual yeast flora.
Glucose-6-phosphate dehydrogenase from Neisseria gonorrhoeae: partial characterization of the enzyme and inhibition by long-chain fatty acid acyl-coenzyme A derivatives
Authors: Cacciapuoti Anthony F. , Morse Stephen A.
Published: May 2010

The glucose-6-phosphate dehydrogenase from Neisseria gonorrhoeae was inhibited by long-chain fatty acid acyl-coenzyme A derivatives. The inhibition was increased at low concentrations of glucose 6-phosphate and was greater with the NAD-linked activity (ca. 0.05 mM inhibitor required for 50% inhibition) than with the NADP-linked activity (ca. 0.2 mM required for 50% inhibition). Bovine serum albumin and spermine could prevent the inhibition by the acyl-coenzyme A derivatives, but neither of these compounds nor high concentrations of cofactors or substrate could reverse the effect. Dilution of enzyme–inhibitor preincubation mixtures appeared to reverse the inhibition. The inhibition by stearoyl-coenzyme A was of the mixed type, and the inhibitor appeared to have a greater affinity for the free enzyme (Ki = 0.016–0.05 mM) than for enzyme bound to cofactor or substrate (Kis = 0.07–0.08 mM). Glucose-6-phosphate dehydrogenase activity was also inhibited competitively by adenosine 5′-triphosphate and was strongly regulated by adenylate energy charge values between 0.9 and 1.0. Kinetic and other characteristics of the enzyme are presented, and the possible role of glucose-6-phosphate dehydrogenase as a target for fatty acid toxicity in gonococci, mediated in the form of the acyl-coenzyme A derivatives, is discussed.
Viability and depletion of cell constituents of Methanospirillum hungatii GP1 during starvation
Authors: Breuil C. , Patel G. B.
Published: May 2010

The viability of Methanospirillum hungatii GP1 cells dropped rapidly when starved in a pH 7.0 phosphate buffer under 100% N2 or 90% N2 – 10% H2 gas phase. The presence of H2 during starvation tests resulted in a more rapid and an ultimately greater reduction of the number of initially viable cells than in the presence of N2 only. The decrease in viability was observed concurrently with the decline of the ATP pool and the RNA content of the cells. The cell protein, carbohydrate, and amino acid pool also decreased. The cellular DNA content which increased initially under both gas phases subsequently decreased under N2–H2 gas phase. However, there was no net decline in the DNA content of the cells. The results indicate that M. hungatii would not survive prolonged periods of starvation.
Relationship of primer specificity of fatty acid de novo synthetase to fatty acid composition in 10 species of bacteria and yeasts
Authors: Kaneda Toshi , Smith E. J.
Published: May 2010

Fatty acid compositions of lipids from six bacteria and four yeasts were determined. Fatty acid de novo synthetases were investigated with respect to chain length specificity towards acyl-CoA primers of various chain lengths.Four species of bacteria (Bacillus subtilis, Corynebacterium cyclohexanicum, Micrococcus luteus, and Pseudomonas maltophilia) possess branched-chain fatty acids of the iso and anteiso series as the major acids. De novo synthetases from these organisms exhibited specificity towards the chain length of the primer in the order butyrl-CoA > propionyl-CoA [Formula: see text] acetyl-CoA. The remainder, two bacteria and all four yeasts, have the straight-chain type of fatty acids only and fall into two groups: (1) Eschericia coli B, Pseudomonas fluorescens, and Saccharomyces cerevisiae, which utilize the primers in the order acetyl-CoA > propionyl-CoA [Formula: see text] butyryl-CoA; and (2) Candida sake, Candida tropicalis, and Rhodolorula glutinis, which show the order propionyl-CoA > acetyl-CoA [Formula: see text] butyryl-CoA.L-α-Keto-β-methylvalerate, a precursor of the branched-chain primers, can be used as a source of primer for fatty acid synthesis by the organisms with branched-chain acids but not by those with the straight-chain type.The results indicate that organisms having straight-chain fatty acids lack the branched-chain equivalents for two reasons: first, their enzymes are not active toward primers with more than three carbons, and second, they lack a system of supplying suitable branched-chain primers.It appears that activities of de novo synthetases from the organisms having straight-chain fatty acids generally have much higher activities than those from the organisms possessing branched-chain fatty acids.
Influence of S-adenosylmethionine on DAPI-induced fluorescence of polyphosphate in the yeast vacuole
Authors: Allan R. A. , Miller J. J.
Published: May 2010

Use of the fluorochrome 4′,6-diamidino-2-phenylindole∙2 HCl (DAPI) in ultraviolet microscopy revealed fluorescent objects in Brownian motion within the vacuoles of seven species of yeast. The abundance of these bodies increased when cells of Saccharomyees cerevisiae were transferred from growth medium to a glucose–phosphate solution, indicating that they contain polyphosphate. In addition, the effect on vacuolar fluorescence of supplementing a defined growth medium with amino acids provided evidence that they also contained S-adenosylmethionine. These deductions were supported by in vitro studies of the interaction and fluorescence of polyphosphate, S-adenosylmethionine, and DAPI. Vacuolar fluorescence of cells in suspension in glucose–phosphate solution was less after addition of exogenous arginine, lysine, or glutamine but not after addition of alanine, aspartic acid, or methionine.Mithramycin was superior to DAPI as a fluorochrome for ultraviolet demonstration of yeast nuclei since it stained the nuclei much more intensely and did not fluoresce with other material in the cells.
DNA-mediated transformation in mutants of phage group 2 Staphylococcus aureus
Authors: Martin Scott M. , Rogolsky Marvin
Published: May 2010

A large pool of antibiotic resistant and auxotrophic mutants was isolated from the Staphylococcus aureus phage group 2 strains UT0002-19 and UT0017 by (1) antibiotic gradient plates, (2) trimethoprim selection, and (3) nitrosoguanidine mutagenesis, which sometimes was coupled by enrichment with either penicillin or methicillin. Strain UT0002-19 has a chromosomal determinant for exfoliative toxin (ET), which causes "scalded skin syndrome" in man. A few mutants were isolated from the phage group 1 strain UT0080, which also produces ET. Two transformation regimens, called the broth and plate methods, were devised for the phage group 2 strains. They employed 80α as helper phage, and recipient cells were incubated with transforming DNA in the presence of Ca2+. Strain UT0080 was transformed using phage 55 as helper. Maximum competence of the phage group 2 strains occurred during early logarithmic growth in trypticase soy broth, but cells grown overnight on heart infusion agar were also competent. Transformation frequencies of all markers ranged from 10−6 to 10−8. For phage 80α, a multiplicity of infection of 4 was optimal in transforming a mutant of strain UT0002-19. Transformation of gly, lin, met, ole, rif, and ser markers in S. aureus is reported for the first time. Ery and ole markers in all three strains exhibited cross-resistance. Mapping studies, similar to those performed by DNA-mediated transformation in the phage group 3 strain 8325, can now be commenced for phage group 2 strains of S. aureus in order to elucidate the molecular genetics of this medically important bacterium.
Extracellular nucleases of Lysobacter enzymogenes: production of the enzymes and purification and characterization of an endonuclease
Authors: Tigerstrom Richard G. von
Published: May 2010

Lysobacter enzymogenes produced a nonspecific extracellular nuclease and an extracellular RNAase when grown in tryptone broth. Both enzyme activities appeared after the exponential growth phase of the organism. The addition of RNA to the medium specifically inhibited the production of the nuclease and the addition of phosphate prevented the synthesis of the RNAase. DNA had no effect on the enzyme production. The Lysobacter nuclease was purified 274-fold and its molecular weight was estimated to be between 22 000 and 28 000. Freshly purified nuclease showed one major protein band and one major activity band on polyacrylamide gels, whereas two major bands were seen after prolonged storage of the enzyme. The nuclease was most active at pH 8.0 and required Mg2+ or Mn2+. Little activity was obtained in the presence of Ca2+. The enzyme degraded double-stranded DNA more rapidly than single-stranded DNA or RNA and was essentially inactive with poly(A) or poly(C) as the substrate. Extensive hydrolysis of double-stranded DNA by the enzyme yielded oligodeoxyribonucleotides with terminal 5′-phosphate groups. The Lysobacter RNAase appeared to have a molecular weight approximately twice that of the nuclease and was specific for ribonucleotide polymers.
Thiobacillus acidophilus: a study of its presence in Thiobacillus ferrooxidans cultures
Authors: Arkesteyn G. J. M. W. , Bont J. A. M. de
Published: May 2010

A study had been undertaken to account for the presence of Thiobacillus acidophilus in iron-grown cultures of Thiobacillus ferrooxidans. Attempts to adapt T. acidophilus to ferrous iron were not successful but the facultative autotroph grew to a limited extent in the spent medium of T. ferrooxidans and was able to grow oligotrophically. Possible oligotrophic substrates were methanol, ethanol, and sulphide. Thiobacillus ferrooxidans may benefit from the presence of T. acidophilus because in mixed cultures some inhibiting organic compounds such as alcohols, organic acids, and amino acids were utilized by T. acidophilus. The number of T. acidophilus cells in heterogeneous cultures with T. ferrooxidans was of the same order of magnitude as the number of T. ferrooxidans cells as revealed by fluorescent-labelled antibodies.
The formation of microcolonies by rumen bacteria
Authors: Cheng K.-J. , Costerton J. W.
Published: May 2010

When rumen fluid is fixed for electron microscopy, without centrifugation, a large amount of material sediments spontaneously and ruthenium red staining shows this material to be partially composed of bacterial microcolonies in which morphologically similar sister cells are enclosed in an extensive fibrous exopolysaccharide glycocalyx. The exopolysaccharide matrix condenses, to variable degrees, during the dehydration steps of specimen preparation for electron microscopy but some fibers are stabilized by their attachment to solid surfaces at multiple points and the extent of this matrix can be deduced from morphological data. Even after condensation, the glycocalyces of rumen bacteria occupy more space than the cells themselves and they completely surround most cells with a fibrous matrix, whose chemical composition dictates an ion-exchange function, that must be assumed to be protective against some bacteriophage and antibacterial agents.
Sequential nitrification by an Alcaligenes sp. and Nitrobacter agilis
Authors: Castignetti Domenic , Gunner Haim B.
Published: May 2010

The ecological importance of heterotrophic nitrification has been difficult to assess because of low levels of nitrification associated with this phenomenon. Nitrification by a soil isolate, an Alcaligenes sp., which oxidizes pyruvic oxime to produce up to 1867 mg nitrite-nitrogen/L, is described. Sequential nitrification with the chemoautotroph Nitrobacter agilis, ATCC 14123, resulted in nitrate accumulation and a concomitant decrease of the nitrite produced by the Alcaligenes sp. when the bacteria were jointly cultured. The ecological significance of such a sequential system is discussed.
Lytic enzymes in the autolysis of Schizophyllum commune with special reference to 1,3-α-glucanase
Authors: Reyes Fuensanta , Lahoz R. , Vazquez Covadonga
Published: May 2010

In the autolytic phase of growth Schizophyllum commune lost 62% of its dry weight in 70 days of incubation. The variations in the activity of some lytic enzymes were studied in the culture fluid and mycelial extracts during growth and autolysis of this fungus. The enzymes 1,3-β-glucanase (exoglucanase), 1,3(4)-β-glucanase (endoglucanase), α-amylase, and invertase behaved in the same way inculture fluid and mycelial extract, but their activities were much higher in the culture fluid. The enzyme activities increased during autolysis, but then decreased at the end of this period except in the case of α-amylase which remained high. It was only possible to detect 1,6-β-glucanase, cellulase, and polygalacturonase activities at certain times during the autolytic phase of growth. The enzyme chitinase was not detected and 1,3-α-glucanase (S-glucanase) occurred in the mycelial extract at a higher concentration than in the culture fluid. A decrease in the activity of this enzyme in the mycelial extract and an increase in the culture fluid occurred during autolysis. The enzyme 1,3-α-glucanase exhibited two optima pH, one at 6.0 and the other at 8.0. The Km value for the latter was 0.02 M at pH 5.5 in borate–citrate–phosphate buffer.
Hyphal tip growth in Achlya. I. Cytoplasmic organization
Authors: Hill T. W. , Mullins J. T.
Published: May 2010

Growing apices of Achlya ambisexttalis Raper hyphae were examined by electron microscopy using cytochemical techniques. Apical vesicles can be grouped into two major classes based upon size and cytochemical reactions. Vesicles of the most prominent class are about 150 nm in diameter and possess contents which appear fibrous in thin section. This fibrous material reacts positively with the periodic acid – silver methenamine (PASM) cytochemical test for polysaccharides. Most of these same vesicles also display IDPase activity, and a smaller number display acid phosphatase activity. Vesicles of the second class are about 80 nm in diameter, and include coated vesicles and others which react positively for IDPase activity. They show a negative PASM reaction in contrast with the larger vesicles. Some of these smaller vesicles are stained by the phosphotungstic acid – chromic acid (PTA–CrO3) stain, whereas 150-nm vesicles are not. The source of at least some vesicles of both major classes appears to be the Golgi apparatus. It is proposed that the IDPase activity and carbohydrate content of the 150-nm cytoplasmic vesicles could serve as useful markers in their isolation.
The preparation of transforming DNA from Mycoplasma hominis strain Sprott tetr and quantitative studies of the factors affecting the genetic transformation of Mycoplasma salivarium strain S9 tets to tetracycline resistance
Authors: Cerone-McLernon Anna M. , Furness Geoffrey
Published: May 2010

DNA extracted by a standard method from Mycoplasma hominis Sprott, resistant to 100 μg tetracycline, permitted the quantitative genetic transformation of tetracycline-sensitive Mycoplasma salivarium to resistance. The yield was 1 μg DNA/109 cells. This DNA enabled determination of the optimum conditions for making M. salivarium competent with CaCl2 and for studying some factors affecting transformation. Mycoplasma salivarium was transformed to resistance to 10, 20, and 30 μg tetracycline but not to 40 μg. The optimum DNA concentration for transforming resistance to 10, 20, and30 μg tetracycline was the same, i.e., 50 μg DNA/108 viable cells. Treatment with DNase indicated that DNA uptake took 30 min. Competition between transforming DNA and DNA from calf thymus and M. salivarium tets inhibited transformation.
Ultrastructure of sporulating cells of Clostridium perfringens type A grown in the presence of raffinose
Authors: Labbe Ronald G. , Rufner Robyn
Published: May 2010

Seven-hour sporulating cells of Clostridium perfringens type A strain NCTC 10240 grown in the presence of raffinose versus starch were larger, produced a thicker cortex, and were altered in spore coat structure. Strain NCTC 8798 possessed an expanded subcoat region and (or) produced coat fragments when grown in the presence of raffinose.
Growth of yeasts on D-xylulose
Authors: Wang Patrick Y. , Schneider Henry
Published: May 2010

Nine of eleven yeasts of different species or genera grew in the presence of air on the intermediate of D-xylose catabolism, D-xylulose (D-threo-pentulose). Growth on this substrate was efficient as judged by the optical density in stationary phase being generally similar to that after growth on glucose. Yeasts which grew on D-xylose also did so on D-xylulose, but among those which grew are included several which utilise neither D-xylose nor xylitol: Saccharomyces cerevisiae, Saccharomyces carlsbergensis, and Schizosaccharomyces pombe. Since catabolism of a sugar generally requires an initial phosphorylation step, growth of these strains suggests that they contain an enzyme which can function as a D-xylulose kinase. The D-xylulose-5-phosphate formed thereby is considered to enter the pentose phosphate pathway. Glucose-grown inocula of S. carlsbergensis and Schizosaccharomyces pombe, and of several other yeasts, began to grow logarithmically when placed on D-xylulose with no apparent delay, or one which was minimal, suggesting that the D-xylulose kinase was already present in such cells, or was rapidly induced. Petites of S. cerevisiae did not grow on D-xylulose indicating that, in this species, mitochondria are involved in its utilisation.
Evidence that antibodies to polysaccharide alter platelet responses to endotoxin in tolerant rabbits
Authors: Walker Richard I. , Beasley William J.
Published: May 2010

When rabbits are made resistant (tolerant) to Salmonella typhi endotoxin by administration of five intraperitoneal injections of small amounts of endotoxin on consecutive days, a plasma factor appears which accelerates the in vitro aggregation response of platelets to endotoxin. Furthermore, in contrast with the reaction in normal animals, this aggregation is often quickly reversible. The present study was undertaken to determine some characteristics of this plasma factor. The humoral factor responsible for altering the platelet aggregation–disaggregation response to endotoxin is apparently antibody against polysaccharide antigen rather than an endotoxin-degrading substance because (1) appearance of the factor correlated with presence of antibodies to polysaccharide, (2) the factor was stable at 56 °C for 1 h, (3) its effect only took a few seconds to occur, and (4) plasma from tolerant animals reacted only with complete endotoxin, obtained from smooth bacteria, but not lipid A. In fact, lipid A did not induce platelet aggregation unless its specific antibody was also present.
Resistance to trimethoprim and other antibiotics in shigellae isolated in the Province of Ontario
Authors: Bannatyne Robert M. , Toma Sandu , Cheung Rose , Hu Gerard
Published: May 2010

Antimicrobial susceptibility determinations for three commonly used and seven seldom used antibacterial drugs against 482 strains of shigellae isolated in Ontario during 1977 and 1978 were carried out. Resistance to the first-line treatment drugs, ampicillin and tetracycline, occurred in 20.5 and 39.2% of strains, respectively. The emergence of trimethoprim–sulfamethoxazole resistance was noted for the first time in 3.2% of the strains in 1978. All strains retained their susceptibility to gentamicin, nalidixic acid, and polymyxin but were variably susceptible to chloramphenicol, cephalexin, and rifampin.
Cytochrome oxidase of Nitrobacter agilis: isolation by hydrophobic interaction chromatography
Authors: Chaudhry Ghulam R. , Suzuki Isamu , Lees Howard
Published: May 2010

Cytochrome oxidase has been purified from Nitrobacter agilis using hydrophobic interaction chromatography. The purified preparation contained 3–5% phospholipid and migrated as a single band during polyacrylamide gel electrophoresis under nondissociating conditions, but appeared as three bands in the presence of sodium dodecyl sulfate and 6 M urea. These three bands corresponded to molecular weights of 37 000, 25 000, and 13 000.The absorption spectra of cytochrome oxidase isolated from Nitrobacter were similar to those reported for a-type cytochrome oxidase from other sources and exhibited absorption maxima at 420 and 600 nm when oxidized and 443 and 606 nm when reduced. The purified enzyme reacted both with horse heart and Nitrobacter cytochrome c.The enzymatic activity depended upon the pH of reaction mixture, with the maximum activity at pH 6.5 and 7.5 for Nitrobacter and horse heart cytochrome c, respectively. The activity of the purified enzyme was inhibited by cyanide, azide, and diethyl dithiocarbamate.
Dinitrogen-fixing bacteria: computer-assisted identification of soil isolates
Authors: Rennie R. J.
Published: May 2010

Dinitrogen-fixing (acetylene-reducing) bacteria may be readily isolated from soils but extensive biochemical or immunological testing, or both, are required to identify them absolutely. A computer-assisted scheme for identification of nine genera of dinitrogen-fixing bacteria was developed and tested. The computer program is based on interpretation of the 70 biochemical tests of the API 20E and 50E, supplemented with tests for acetylene reduction, nitrate and nitrite reduction, catalase, oxidase, motility, and growth on MacConkey's bile salt medium. Dinitrogen-fixing Enterobacteriaceae (Klebsiella pneumoniae, Enterobacter cloacae, and Erwinia herbicola) were accurately identified using the data base in the API analytical profile index. Nonenteric dinitrogen-fixing bacteria (Azotobacter spp., Azospirillum spp., Derxia sp., Rhodospirillum sp., Clostridium sp., and Bacillus spp.) were subjected to these tests to form a new data base for these bacteria. The API tests agreed with standard biochemical tests commonly used to identify these bacteria, were reproducible with time, and were sufficiently unique to permit accurate identification of each species. The use of the API 20E and 50E tests plus the additional seven tests with these known data bases permitted rapid and precise identification of acetylene-reducing bacteria from various agricultural ecosystems.
Strategies of response to copper, cadmium, and lead by a blue-green and a green alga
Authors: Laube V. M. , McKenzie C. N. , Kushner D. J.
Published: May 2010

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 concentration of Cu(NO3)2 (10−5 M) most of the Cu was found outside the cell, in a 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 blooms of such algae might have on the mobilization of these metals from sediments in natural waters are discussed.
Concentration and purification of rubella virus hemagglutinin by hollow fiber ultrafiltration and sucrose density centrifugation
Authors: Trudel M. , Payment P.
Published: May 2010

Large volumes of rubella virus were produced in Vero cell monolayers which were grown in the Corbeil-Bellco TM system. Infectious tissue culture fluids were concentrated at least 600 times in less than 4 h by ultrafiltration on hollow fibers with a molecular weight cutoff of 100 000. Recovery of the hemagglutinating activity was 75%. Rubella virus was purified by three successive sucrose density gradient centrifugations using a combination of discontinuous and linear gradients. Specific activity was increased 1000-fold.
DNA homology among diverse spiroplasma strains representing several serological groups
Authors: Lee I.-M. , Davis R. E.
Published: May 2010

Deoxyribonucleic acid (DNA) homology among 10 strains of spiroplasma associated with plants and insects was assessed by analysis of DNA–DNA hybrids with single strand specific S1 nuclease. Based on DNA homology, the spiroplasmas could be divided into three genetically distinct groups (designated I, II, and III), corresponding to three separate serogroups described previously. DNA sequence homology between the three groups was ≤5%. Based on DNA homology, group I could be divided into three subgroups (A, B, and C) that corresponded to three serological subgroups of serogroup I. Subgroup A contained Spiroplasma citri strains Maroc R8A2 and C 189; subgroup B contained strains AS 576 from honey bee and G 1 from flowers; subgroup C contained corn stunt spiroplasma strains 1-747 and PU 8-17. There was 27–54% DNA sequence homology among these three subgroups. Group II contained strains 23-6 and 27-31 isolated from flowers of tulip tree (Liriodendron tulipifera L.). Group III contained strains SR 3 and SR 9, other isolates from flowers of tulip tree. Based on thermal denaturation, guanine plus cytosine contents of DNA from five type strains representing all groups and subgroups were estimated to be close to 26 mol% for group I strains, close to 25 mol% for group II strains, and close to 29 mol% for group III strains. The genome molecular weights of these five type strains were all estimated to be about 109.
An estuarine agar medium for enumeration of aerobic heterotrophic bacteria associated with water, sediment, and shellfish
Authors: Weiner Ronald M. , Hussong David , Colwell Rita R.
Published: May 2010

A plate count agar was formulated for use in bacteriological analysis of estuarine samples and was tested together with standard plate count agar and an estuarine salts yeast extract agar for growth of aerobic, heterotrophic bacteria in water, sediment, and oysters. The estuarine agar was found to be efficient for enumerating aerobic, heterotrophic bacterial populations of water, sediment, and oysters, and is recommended for plate counts of estuarine samples.
CORRELATIONS BETWEEN OXY-HEMOGLOBIN AND RESPIRATORY EXCHANGE RATIO IN THE QUADRICEPS DURING THE EARLY PHASE OF EXERCISES
Authors: XU GUODONG , YE YANJIE
Published: May 2010

The early stage of exercises is crucial in sports training; however, its physiological mechanism is still unclear. The hemodynamic response was reported to be associated with respiratory exchange. Here, we aimed to explore the relationship between oxy-hemoglobin concentration change ( HbO2 ) and respiratory exchange ratio (RER) during the early phase of exercises. Sixteen athletes of middle-distance race were selected from Wuhan Institute of Physical Education to conduct intermittent exercises on MERCURY4.0 at 80% VO2peak intensity. Multiple physiological parameters were acquired by use of a near-infrared spectroscopy muscle oxygen monitor, a Cardiopulmonary Function MAX-II and a P-Lar, including HbO2 , RER and others. A significant correlation was found between RER and HbO2 in quadriceps muscle in the thigh during the early phase of exercises. Thus, NIRS is capable of supervising sports training in terms of HbO2 , which actually acted as an interpreter of RER change.
RESEARCH ON WATER QUALITY TESTS BASED ON OPTICAL WAVEGUIDE SURFACE PLASMON RESONANCE TECHNOLOGY
Authors: YUAN XIUHUA , ZHAO MING , ZENG YAN'AN
Published: May 2010

The water quality testing principle by surface plasmon resonance (SPR) is introduced. Using the scanning mode angular spectral testing and the CCD angular spectral testing, a kind of high-resolution, wide-range, and portable optical waveguide SPR angular spectral testing system is studied, the method of improving the testing accuracy is discussed, and a long-life surface plasmon optical waveguide transducer is also proposed. Utilizing the SPR testing system, we contrastively tack some test for several sorts of solution, the results presented that significant differences of SPR peaks observed in different sorts of liquid, which indicated the effectiveness of SPR technology used in water quality testing and analysis.
Enhanced Nucleation of Microcrystalline Silicon Thin Films Deposited by Inductively Coupled Plasma Chemical Vapor Deposition with Low-Frequency Pulse Substrate Bias
Authors: Furuta Mamoru , Hiramatsu Takahiro , Hirao Takashi
Published: May 2010

Microcrystalline silicon (µc-Si) films were deposited by inductively coupled plasma chemical vapor deposition with a low-frequency and low-duty pulse substrate bias (PSB). The crystallinity of the films was significantly improved by the PSB. In the case of the low-frequency and low-duty PSB, the duty ratio affected the crystallinity more than the negative peak voltage. Cross-sectional transmission electron microscopy measurements revealed that the nucleation density at the µc-Si/glass interface was increased by the PSB. This technique will be useful in fabricating high-performance bottom-gate µc-Si thin-film transistors for large-area electronics.
Piezoelectric Wind-Energy-Harvesting Device with Reed and Resonant Cavity
Authors: Ji Jun , Kong Fanrang , He Liangguo , Guan Qingchun , Feng Zhihua
Published: May 2010

A wind-energy-harvesting device utilizing the principle of a harmonica was created. A reed in a resonant cavity vibrated efficiently with the blowing wind, and a piezoelectric element stuck on the reed generated electricity. The dimensions of the wind inlet were approximately 30×20 mm2. The device was investigated with a wind speed ranging from 2.8 to 10 m/s. An output power of 0.5–4.5 mW was obtained with a matching load of 0.46 MΩ. The energy conversion efficiency of the device could reach up to 2.4%.
Athermal Wavelength Characteristics of Si Slot Ring Resonator Embedded with Benzocyclobutene for Optoelectronic Integrated Circuits
Authors: Atsumi Yuki , Inoue Keita , Nishiyama Nobuhiko , Arai Shigehisa
Published: May 2010

An athermal Si-slot-waveguide ring resonator embedded with benzocyclobutene (BCB), a low-k material used in electronics, was proposed. By controlling the width of the BCB-filled gap to 90 nm, the temperature coefficient of equivalent index of a Si slot waveguide could be reduced to 3.70×10-6, which is two orders of magnitude smaller than that of a conventional Si waveguide. The dependences of peak wavelength shift on temperature in the fabricated devices of a conventional Si wire waveguide with SiO2 cladding, Si wire waveguide with BCB cladding, and Si slot waveguide with BCB cladding were 26, 17, and -0.6 pm/K, respectively.
Fabrication of Epitaxial Silicon Thin Films for Solar Cells by Low-Temperature Reactive Thermal Chemical Vapor Deposition Technique
Authors: Minowa Akihisa , Kondo Michio
Published: May 2010

Low temperature reactive thermal chemical vapor deposition (RT-CVD) with a mixture of SiH4 and F2 gases has been developed to obtain silicon films with a relatively thick epitaxial layer for solar cell applications. It was found that an epitaxial layer with good crystallinity and a “2×1 structure” can be grown at approximately 400 °C up to a thickness of 3.0 µm and that the epitaxial growth shows a sudden breakdown at 3.2 µm to result in an amorphous phase. The growth mechanism, which determines the crystallinity for thicker layers, is discussed on the basis of hydrogen content and lattice distortion.
Efficient controls for finitely convergent sequential algorithms
Authors: Chen Wei , Herman Gabor T.
Published: May 2010

Finding a feasible point that satisfies a set of constraints is a common task in scientific computing; examples are the linear feasibility problem and the convex feasibility problem. Finitely convergent sequential algorithms can be used for solving such problems; an example of such an algorithm is ART3, which is defined in such a way that its control is cyclic in the sense that during its execution it repeatedly cycles through the given constraints. Previously we found a variant of ART3 whose control is no longer cyclic, but which is still finitely convergent and in practice usually converges faster than ART3. In this article we propose a general methodology for automatic transformation of finitely convergent sequential algorithms in such a way that (1) finite convergence is retained, and (2) the speed of convergence is improved. The first of these properties is proven by mathematical theorems, the second is illustrated by applying the algorithms to a practical problem.
Efficient and formally proven reduction of large integers by small moduli
Authors: Rutten Luc , Van Eekelen Marko
Published: May 2010

On
w
-bit processors which are much faster at multiplying two
w
-bit integers than at dividing 2
w
-bit integers by
w
-bit integers, reductions of large integers by moduli
M
smaller than 2

w
-1

are often implemented suboptimally, leading applications to take excessive processing time.

We present a modular reduction algorithm implementing division by a modulus through multiplication by a reciprocal of that modulus, a well-known method for moduli larger than 2

w
-1

. We show that application of this method to smaller moduli makes it possible to express certain modular sums and differences without having to compensate for word overflows.

By embedding the algorithm in a loop and applying a few transformations to the loop, we obtain an algorithm for reduction of large integers by moduli up to 2

w
-1

. Implementations of this algorithm can run considerably faster than implementations of similar algorithms that allow for moduli up to 2

w

. This is substantiated by measurements on processors with relatively fast multiplication instructions.

It is notoriously hard to specify efficient mathematical algorithms on the level of abstract machine instructions in an error-free manner. In order to eliminate the chance of errors as much as possible, we have created formal correctness proofs of our algorithms, checked by a mechanized proof assistant.