bluuebunny/crossref_metadata_2025 huggingface dataset:
Cache Valley virus: isolations from mosquitoes in Saskatchewan, 1972–1974
Authors: Iversen J. O. , Wagner R. J. , Leung M. K. , Hayles L. B. , McLintock J. R.
Published: April 2010

Eighteen isolations of Cache Valley virus (Bunyaviridae) were obtained from a total of 113 694 mosquitoes collected in Saskatchewan during the summers of 1972 to 1974. Most of the isolations were from mosquitoes collected during August. Culiseta inornata, the most abundant mosquito (38% of total collected), had the highest minimum vector-infection rate (0.83 isolations per 1000 mosquitoes). The virus was also isolated from Culex tarsalis and Aedes texans. It is indicated in the isolations that the prairie grasslands of the province are enzootic for Cache Valley virus.
Bioconversion of wheat straw and wheat straw components into single-cell protein
Authors: Chahal D. S. , Moo-Young M. , Dhillon G. S.
Published: April 2010

Several fungi (Aspergillus niger, A. terreus, Cochliobolus specifer, Myrothecium verrucaria. Rhizoctonia solani, Spicaria fusispora. Penicillium sp., and Gliocladium sp.) were isolated from decomposing wheat straw and tested for their ability to utilize whole straw and its components, holocellulose (hemicellulose and cellulose) and cellulose, for the production of single-cell protein (SCP). It was found that C. specifer was the most efficient fungus for protein synthesis with the three substrates. Using potassium nitrate as N source in mixtures of 0.04 g N/g substrate (0.04% wt./vol.) at pH 4.5, it was found that incubation periods of 3. 4, and 5 days were optimal for protein production on cellulose and holocellulose fractions, and whole straw, respectively. Whole native straw was found to be the most recalcitrant to bioconversion into SCP; however, protein production was almost doubled when the lignin component was removed using a mixture of sodium chlorite and acetic acid.
The effect of phenazine methosulfate-ascorbate on bacterial active transport and adenosine triphosphate formation: inhibition of Pseudomonas aeruginosa and stimulation of Escherichia coli
Authors: Eagon R. G. , Hodge III T. W. , Rake J. B. , Yarbrough J. M.
Published: April 2010

The artificial electron-donor system, phenazine methosulfate (PMS) ascorbate, inhibited active transport of glucose by Pseudomonas aeruginosa irrespective of whether the incubation systems were in air, flushed with oxygen, or gassed with nitrogen under anaerobic denitrifying conditions. Active transport of glucose by P. aeruginosa was also inhibited by reduced 5-N-methyl-phenazonium-3-sulfonate, a membrane-impermeable electron donor. PMS–ascorbate caused rapid depletion of intracellular adenosine triphosphate (ATP) when added to respiring cell suspensions of P. aeruginosa either in the presence or absence of glucose or succinate as oxidizable energy sources. In contrast, under identical conditions, Escherichia coli formed ATP with PMS–ascorbate as the sole oxidizable energy source and ATP formation continued when glucose or succinate was present in addition to PMS–ascorbate in the incubation system.
Regulation of internal solute concentrations of marine Vibrio alginolyticus in response to external NaCl concentration
Authors: Unemoto Tsutomu , Hayashi Maki
Published: April 2010

Slightly halophilic marine Vibrio alginolyticus grown in the range of NaCl from 0.2 to 1.5 M maintained the total internal solute concentration always higher than the external medium by about 0.25 osM. The concentrations of macromolecules such as DNA. RNA, and protein were little affected by the increase in medium NaCl. The internal K+ concentration was kept to about 400 mM in the range of medium NaCl from 0.4 to 0.8 M; it rose to 510 mM when the bacterium was grown in 1.5 M NaCl, indicating that K+ increased only slightly in response to the large increase in medium NaCl. Thus, in contrast to the case of nonhalophilic and extremely halophilic bacteria, K+ was unlikely to act as a major component to regulate the internal solute concentration of marine V. alginolyticus. The internal Na+ and Cl− concentrations were maintained always lower than those in the growth medium, but they increased in response to the increase in medium NaCl. The concentration of internal Na+ was close to that of K+ at the concentration of medium NaCl that supports the optimal growth of this organism. The total amino acid content of V. alginolyticus increased from 76 to 413 mM by the increase in medium NaCl from 0.2 to 1.5 M. The concentrations of glutamic acid and proline were 254 and 72 mM, respectively, when grown in 1.5 M NaCl. These results indicated that Na+, Cl−, and amino acids, especially glutamic acid and proline, contributed to the regulation of internal solute concentration of V. alginolyticus in response to the increased external NaCl.
Chemotactic responses of Vibrio alginolyticus to algal extracellular products
Authors: Sjoblad Roy D. , Mitchell Ralph
Published: April 2010

A capillary assay was used to evaluate the chemotactic responses of Vibrio alginolyticus to three common algal extracellular products. Acrylate and glycolate attracted the motile marine bacterium. The peak response occurred with 10−2 M of each chemical. Acrylic and glycolic acid also attracted V. alginolyticus, with the peak response occurring at 5 × 10−4 M of each chemical. Higher concentrations of the organic acids resulted in a decreased response. The bacteria also displayed positive chemotaxis to dimethyl sulfide.
Properties of Rhizobium trifolii isolates surviving exposure to specific bacteriophage
Authors: Barnet Yvonne M.
Published: April 2010

Six strains of Rhizobium trifolii were exposed to specific bacteriophages and the properties of 10 surviving clones of each studied. Two temperate bacteriophages produced clones which were lysogenic but showed no changes in colony form, symbiotic properties, or somatic antigens. Of forty clones selected by exposure to four other bacteriophages, none were lysogenic although there was some indication of unusually long association of phage with bacteria in infected cultures. Seventeen of these clones were changed in symbiotic properties, 15 in colony morphology, and 13 in somatic cross-reaction with the parent. Unexpectedly, despite stringent selection conditions, 28 were still either partially or completely susceptible to the selecting phage.
Protective effect of polymyxin B sulfate in experimental enterobacterial infection in mice
Authors: Bannatyne Robert M. , Cheung Rose
Published: April 2010

The mouse model of intraperitoneal enterobacterial sepsis was used to evaluate the anti-endotoxic effect of polymyxin B sulfate. Single or multiple therapeutic doses of polymyxin, administered either before or after lethal challenge with Serratia marcescens, produced statistically and clinically significant protective effects.
Factors affecting germination, mycoparasitism, and survival of Sporidesmium sclerotivorum
Authors: Ayers W. A. , Adams P. B.
Published: April 2010

Macroconidia of Sporidesmium sclerotivorum, a mycoparasite of Sclerotinia spp., germinated after 3 days in soil adjacent to sclerotia of S. minor and on membrane filters placed on soil containing sclerotia. Germination increased with time up to 18 days and with concentration of sclerotia. Conidia as distant as 9 mm from single sclerotia germinated. Germination of conidia was maximum on a sclerotial agar medium in the range of pH 5 to pH7. Cultivation of S. sclerotivorum parasitically on living sclerotia proceeded optimally in moist, fine quartz sand amended with 1 to 2% (w/w) sclerotia and 0.07% (w/w) CaCO3, at 25 °C. Infection of sclerotia in sand reached 100% by 5 weeks. Conidia production paralleled infection resulting in logarithmic increase in numbers; a maximum of 3 × 105 to 4 × 105 conidia/g was reached in 6 to 12 weeks. Viability of air-dried sand–sclerotial cultures of S. sclerotivorum was reduced after 1 and 6 days, but viability was undiminished in air-dried soil. Sporidesmium sclerotivorum survived in moist and air-dried soils stored at room temperature for 15 months.
Etude de l'évolution des populations bactériennes d'origine tellurique, entérique et marine dans des systèmes planctoniques soumis à une pollution urbaine, traitement mathématique des données
Authors: Arfi R. , Bianchi A. , Bianchi M. , Blanc F. , Bonin M. C. , Champalbert G. , Cubizolles F. , David P. , Durbec J. P. , Francois A. , Leveau M. , Lizarraga-Partida M. L. , Marty D. , Maurer D. , Patriti G. , Reys J. P. , Romano J. C. , Sautriot D.
Published: April 2010

A study of the comparative distribution of different types of bacterial populations in the sea area where the city of Marseille rejects its waste water shows that, when in contact with the marine environment, a great part of the allochthonic bacterial population undergoes physiological stress expressed by an abrupt reduction of the effectives and by weak values of the energetic charge.The presence of coliforms and streptococci in waste water lens, at important distances from discharging conduits, shows the possibility of a large diffusion for a fraction of the bacterial populations that withstand the initial stress.From mathematical analyses, an inverse correlation is revealed between detergents and the bacterial population as a whole, and between phenols and various allochthonic bacterial populations.The above results were evidenced through a sampling strategy based upon a 24-h-cycle study and a search for mathematical correlations between several biological, chemical, and physical parameters. [Translated by the journal]
Methionine transport in Pseudomonas aeruginosa
Authors: Montie Thomas C. , Montie Diane B.
Published: April 2010

A high-affinity (Km = 2.7 × 10−7 M) energy-requiring methionine-transport system has been characterized in RM 46 and RM 48, two different PAO methionine auxotrophs of Pseudomonas aeruginosa. After 8 s of transport 40–60% of the methionine label in the alcohol extract appears in S-adenosyl-L-methionine (SAM) with the remaining activity in free methionine. Methionine transport required a high degree of structural specificity for transport. Stimulation of transport occurred by addition of glucose or organic acids. The ability of a given substrate to stimulate transport was related to the type of carbon source used for growth. Transport was sensitive to sulfhydryl reagents and required oxidative phosphorylation, as indicated by the inhibitory effects of anaerobiosis, cyanide, and arsenate. The degree of inhibition by arsenate correlated with the level of ATP in the cell. Rapid transport in a SAM-deficient mutant (TM 1) and inhibition by arsenate of transport in this mutant suggested that SAM formation was not directly linked to transport and that ATP supplied energy for transport. Inhibition by arsenate was more severe in glucose- compared to citrate-stimulated cells. This result was also observed with proline transport indicating that this was not a peculiarity of the methionine-transport system. These data emphasize the close link between glucose metabolism, ATP levels, and transport. This ATP level is not so critical for transport in cells metabolizing citrate.
A simple device for uniform inoculation of nutrient surfaces
Authors: Goulet J. , Levesque G. , Moreau J. R.
Published: April 2010

A simple and inexpensive device for uniform surface inoculation is described. Efficiency and uniformity of inoculation were estimated with agar plates exposed to a bacterial suspension, containing 10 different strains, atomized with a spray gun. The fine mist settled, after a fall of 106 cm, upon the agar surfaces at the bottom of a cylindrical chamber. No significant differences were observed with regard to uniformity of inoculation between nine plates.
Further simplification of the Guizotia abyssinica seed medium for identification of Cryptococcus neoformans and Cryptococcus bacillispora
Authors: Salkin Ira F.
Published: April 2010

A simplified Guizotia abyssinica seed-based medium for presumptive diagnosis of Cryptococcus neoformans and C. bacillispora (Paliwal and Randhawa 1978) was further simplified by replacing seed extract with pulverized seeds. This medium gives unambiguous results, avoids false-positive reactions with 13 other yeastlike organisms, and is simple and relatively inexpensive to prepare.
Use of antisera against bovine (NCDV) and simian (SA11) rotaviruses in ELISA to detect different types of human rotavirus
Authors: Bishai F. R. , Spence L. , Goodwin D. , Petro R.
Published: April 2010

Two ELISA systems for the detection of human rotaviruses were developed. In the first system antibodies to Nebraska calf diarrhea virus (NCDV) were used for coating the solid matrix and for the preparation of the enzyme conjugate. In the second system antibodies to human rotavirus and antibodies to simian rotavirus (SA11) were used for coating the solid matrix and for the preparation of the enzyme conjugate respectively. The second ELISA system proved to have a broader spectrum for the detection of human rotaviruses. By using the two ELISA systems, the different types of human rotavirus could be distinguished. The ELISA tests developed were 8 to 64 times as sensitive as electron microscopy (EM) and (or) counterimmunoelectrophoresis (CIEP). The antigen detected by ELISA was shown to be different from that detected by the hemagglutination test.
Effects of sulfide and acetylene on nitrous oxide reduction by soil and by Pseudomonas aeruginosa
Authors: Tam Tat-Yee , Knowles Roger
Published: April 2010

The production and reduction of nitrous oxide (N2O) after the addition of N2O, nitrite (NO2−), or nitrate (NO3−) was studied in non-sterile soil, in sterilized soil inoculated with Pseudomonas aeruginosa, and in washed cell suspensions of this organism. Sodium sulfide (8 μmol S2− mL−1 or g−1) inhibited N2O reduction markedly in cell suspensions and also in soil, an effect which may cause sulfidic habitats to act as sources of N2O. Sodium thiosulfate (up to 64 μmol S2O32− g−1) showed no such effect. Acetylene (0.02 atm C2H2) completely inhibited the reduction of N2O by soil, but the combination of C2H2 with 8 μmol S2− g−1 permitted the complete reduction of 2 μmol added N2O g−1 within 3 days under the most favourable conditions. Under the same conditions, 8 μmol S2O32− g−1 permitted complete reduction of the N2O within 6 days. The rate of such reduction of N2O was decreased, but not inhibited completely, by raising the C2H2 concentration to 0.11 atm. The data have important implications for the effectiveness of the C2H2 inhibition assay of denitrification in highly anaerobic environments.
Nitrate reductase activities of rhizobia and the correlation between nitrate reduction and nitrogen fixation
Authors: Manhart James R. , Wong Peter P.
Published: April 2010

All species of Rhizobium except R. lupini had nitrate reductase activity. Only R. lupini was incapable of growth with nitrate as the sole source of nitrogen. However, the conditions necessary for the induction of nitrate reductase varied among species of Rhizobium. Rhizobium japonicum and some Rhizobium species of the cowpea strains expressed nitrate reductase activities both in the root nodules of appropriate leguminous hosts and when grown in the presence of nitrate. Rhizobium trifolii, R. phaseoli, and R. legnminosarum did not express nitrate reductase activities in the root nodules, but they did express them when grown in the presence of nitrate. In bacteroids of R. japonicum and some strains of cowpea Rhizobium, high N2 fixation activities were accompanied by high nitrate reductase activities. In bacteroids of R. trifolii, R. leguminosarum, and R. phaseoli, high N2 fixation activities were not accompanied by high nitrate reductase activities.
Biochemical studies on pili isolated from Pseudomonas aeruginosa strain PAO
Authors: Paranchych W. , Sastry P. A. , Frost L. S. , Carpenter M. , Armstrong G. D. , Watts T. H.
Published: April 2010

Pseudomonas aeruginosa strains PAO and PAK bear polar pili which are flexible filaments having a diameter of 6 nm and an average length of 2500 nm. Both types of pili are retractile and promote infection by a number of bacteriophages. The present communication describes the partial biochemical characterization of PAO pili isolated from a multipiliated nonretractile mutant of PAO. The observed properties are compared to those of PAK pili which were characterized previously. PAO pili were found to contain a single polypeptide subunit of 18 700 daltons. This is similar to PAK pili which contain a single polypeptide of 18 100 daltons. The amino acid composition of PAO pilin was also similar to that of PAK pilin. Neither protein contained phosphate or carbohydrate residues and both were found to contain N-methylphenylalanine at the amino terminus. Sequencing of 20 amino acid residues at the amino terminal end of PAO pilin revealed the sequence to be identical with that of PAK pilin, while tryptic peptide analyses of PAO and PAK pilin indicated that the two proteins probably contain a number of homologous regions within the polypeptide. It was concluded that PAO and PAK pili are closely related structures.
The binding of fluorescein-labelled staphylococcal alpha toxoid to erythrocytes
Authors: Barei Gary M. , Fackrell Hugh B.
Published: April 2010

Erythrocytes of different animal species have variable hemolytic sensitivity to staphylococcal alpha toxin. Specific and non-specific binding of toxin was measured using fluorescein-labelled toxoid. These studies indicate that toxoid binding to erythrocytes increases with concentration for all species tested. Scatchard plot analyses of 35 animals representing seven species indicate that rabbit, pig, cow, and chicken erythrocytes possess 125 980, 103 920, 82 500, and 41 200 receptors per cell, respectively. The number of receptors remains constant over a period of at least 10 days. No detectable receptors were found for human, rat, and guinea pig erythrocytes. A correlation coefficient of 0.992 exists between receptor number and hemolytic sensitivity for those species having receptors. Variation in hemolytic sensitivity is governed by receptor number and not by variation in the dissociation constant. A threshold sensitivity of 37 000 receptors per cell has been calculated. Since species lacking detectable receptors have considerable sensitivity to hemolysis, it is proposed that two binding mechanisms, specific and non-specific, exist which prepare erythrocytes for destruction.
A broth-disc technique for the assay of antibiotic synergism
Authors: Meyer Margaret , Hofherr Louise
Published: April 2010

A broth-disc technique has been developed to demonstrate the antibiotic synergism of some broad-spectrum penicillins plus an aminoglycoside against Pseudomonas aeruginosa and enterococci. Utilizing the zone sizes obtained from Kirby–Bauer susceptibility tests, approximate minimum inhibitory concentrations of each antibiotic upon individual isolates were derived using standard regression curves. One-fourth of each value was calculated and the approximate desired concentration then prepared in Mueller–Hinton broth through use of the labelled antibiotic disc content. Tubes were inoculated with a standardized suspension of organism and incubated at 35 °C for 18–24 h. Subsequently, inhibitory end points were recorded.This approach to synergy testing showed good correlation with the standard checkerboard method. The broth-disc synergistic assay is also reproducible, financially feasible, and less time-consuming to execute.
Effect of additions of liquid poultry manure on excretion of degradative enzymes by bacteria in forest soil and litter
Authors: Hankin Lester , Stephens George R. , Hill David E.
Published: April 2010

Liquid poultry manure was applied to three forest sites at 35, 70, and 225 metric tonnes (1 tonne = 1000 kg) per hectare (1 ha = 10 000 m2) for 1 to 3 years. Two of the sites were white pine plantations, one dry, one moist, and the third site was mixed hardwoods. Over a period of 35 months the total bacterial population in litter and in soil, in both control and manure plots, was studied as well as the ability of the population to produce extracellular proteases, cellulases, lipases, pectinases, and amylases. Total bacterial counts in litter tended to be higher in the autumn and lower in the spring. Litter always contained about 10-fold more bacteria than soil and the number of bacteria in soil fluctuated little with season or treatment. In white pine litter, bacteria able to excrete protease were more numerous than other enzyme-producing bacteria. More bacteria able to excrete lipases were found on moist than on dry sites, especially on manured plots. At the end of the 35-month test period, all bacterial counts in manured plots had returned nearly to the original level of the control. Statistical analysis revealed significant differences in total bacterial count and counts of specific enzyme producers between manured and control plots. Little difference was seen among rates of manure application. Adding large amounts of poultry manure to these forest plots did not greatly change the bacterial ecology of the soil or litter.
Effect of glycerol on carotenogenesis in the extreme halophile, Halobacterium cutirubrum
Authors: Kushwaha S. C. , Kates M. K.
Published: April 2010

Growth of cells of Halobacterium cutirubrum in complex medium in the presence of 0.1 to 0.5% glycerol was slightly stimulated (about 10%), but the content of the major red pigment, bacterioruberin, was reduced fourfold and that of the minor red pigments, mono- and bisanhydrobacterioruberins, was also reduced but to a lesser extent. The content of the C40 carotenes, β-carotene and lycopene, however, was greatly increased in 0.1 to 0.5% glycerol but was then reduced to negligible amounts at higher glycerol concentrations (1 to 5%). Similar effects of glycerol on carotenogenesis were observed when cells were grown in a chemically defined medium (BSMK), but growth of cells was considerably slower.
Studies of the biosynthesis of C50 carotenoids in Halobacterium cutirubrum
Authors: Kushwaha S. C. , Kates M.
Published: April 2010

Cells of Halobacterium cutirubrum were grown in the presence of [14C]mevalonate with and without 3 mM nicotine. Growth of cells was inhibited to a maximum extent of 25% but overall incorporation of 14C into total, neutral, or polar lipids was only inhibited about 16% during active growth and to a much lesser extent or not at all in stationary phase. Little effect of nicotine on labelling of squalenes, vitamin MK-8, geranylgeraniol, and phytoene was observed. However, labelling of bacterioruberin and monoanhydrobacterioruberin was extensively inhibited while that of lycopene and bisanhydrobacterioruberin was increased reciprocally by growth in the presence of 3 mM nicotine. Reincubation of the labelled nicotine-grown cells in fresh cold medium without nicotine restored the 14C-labelling of bacterioruberin and monoanhydrobacterioruberin at the expense of lycopene and bisanhydrobacterioruberin. These results confirm our previous findings suggesting that the C50 bacterioruberin is made by addition of a C5-isoprene unit to each end of the C40-lycopene chain, followed by introduction of four hydroxyl groups.
Polioviruses and other enteroviruses in urban sewage from Laval (Canada): presence of non-vaccinal strains of poliovirus
Authors: Payment P. , Larose Y. , Trudel M.
Published: April 2010

During a 13-month period (August 1, 1977–August 3 1, 1978) 55 samples of 2–4 L of raw sewage from an urban residential area were collected and studied for the presence of human enteroviruses. Viruses were recovered from 47 (90.5%) of the samples. Of the 201 viral isolates propagated, 180 (89.5%) were identified by the serum neutralization test as poliovirus types 1, 2, or 3; 16 (8%) were identified as coxsackie B viruses; and 5 (2.5%) could not be identified by the methods used. While all polioviruses, types 2 and 3 isolates, were vaccine-like (rct−/d−) or intermediate strains, 14 poliovires, type 1 out of 55 selected isolates, were found to be non-vaccine-like (rct+/d+), 8 were rct−/d−). and 33 were intermediate strains. Out of nine samples submitted to the serodifferentiation (McBride) test, six poliovires, type 1 rct+/d+ and three rct+/d−, were related to wild strains.
Influence of soil texture on survival and saprophytic activity of Rhizoctonia solani in soils
Authors: Lewis J. A.
Published: April 2010

Survival of Rhizoctonia solani in precolonized tablebeet seed was greater in a light-textured sandy loam (SL 1) than in a heavy-textured silty clay loam (SiCL). Reduction in survival as well as competitive saprophytic activity of the pathogen resulted when clays (kaolinite and montmorillonite) were added to SL to prepare soils of heavier texture. Survival and activity R. solani, however, were not increased when sand was added to SiCL (suppressive to R. solani survival) to make this soil lighter in texture. In natural soils of different textures, activity of R. solani was maintained longer in two light-textured sandy loam soils than in a light-textured loamy sand or loam. During investigation of soil chemical and biological influences on R. solani survival, high K2O content in soil was significantly correlated with low saprophytic activity of the pathogen. In all instances where soil microbial activity as determined by a dehydrogenase assay was high, low saprophytic activity was found. Since high microbial activity or K2O content in soil were not associated with any particular soil type, biological or chemical factors may be more important than soil texture in influencing survival and activity of R. solani in soil.
Dissolved organic matter utilization and oxygen uptake in algal–bacterial microcosms
Authors: Tison David L. , Lingg A. J.
Published: April 2010

Under closed laboratory conditions, at non-limiting nutrient levels, the biomass of Anabaena variabilis. Anacystis nidnlans, Chlorella pyrenoidosa. and Selanastrum capricornutum increased with increasing levels of dissolved organic matter (DOM) as a result of bacterially produced carbon dioxide (CO2) and (or) cofactors. Oxygen (O2) produced as a result of algal photosynthesis was sufficient to supply the majority of O2 required by the bacterial community. The percentage of DOM utilized by bacteria which was subsequently incorporated into algal biomass varied with individual species indicating that the association between individual algal species and the bacterial microbiota varied.Under natural conditions bacteria could provide CO2 and (or) cofactors for algal photosynthesis which in turn supplies O2 for bacterial respiration. This mutualistic association in aquatic environments could result in an increase in planktonic and epiphytic algal biomass if other nutrients are available.
The role of temperate bacteriophage SPβ in prophage-mediated interference in Bacillus subtilis
Authors: Rettenmier Carl W. , Gingell Barry , Hemphill H. Ernest
Published: April 2010

Virulent bacteriophage [Formula: see text] grows on a variety of Bacillus subtilis strains. Mutants of this virus which abortively infect the transformable bacillus, B. subtilis 168, while retaining the ability to productively infect related bacteria have been found. In the present study, we demonstrate that the inability of one such variant, [Formula: see text], to develop normally in strain 168 is mediated by cryptic prophage SPβ. The latter is a temperate bacteriophage which is carried by B. subtilis 168 and most strains derived from this bacterium. [Formula: see text] infection of SPβ lysogens begins with apparently normal adsorption, penetration, and initiation of virus-directed syntheses. At about the 20th min of the latent period, however, there is an abrupt cessation of nucleic acid synthesis and cellular respiration, accompanied by a change in cell permeability. This course of events can be altered to a permissive infection by mutation in the mpi gene of SPβ, by mutation in the spo0A gene of the host, or by growing SPβ lysogens at high temperature. In addition, we found a second class of [Formula: see text] mutants which abortively infect B. subtilis 168 derivatives even in the absence of the SPβ prophage.
Indigenous bacteria influence the number of Salmonella typhimurium in the ileum of gnotobiotic mice
Authors: Roach Sally , Tannock Gerald W.
Published: April 2010

Gnotobiotic BALB/c mice associated with indigenous Lactobacillus, Bacteroides, and two fusiform-shaped Clostridium strains had fewer S. typhimurium present in the ileum 3 days after intragastric challenge with the pathogen than did similarly challenged germfree mice. Acetic and butyric acids were detected in the caecal contents of the gnotobiotic mice, but in smaller concentration than was present in conventionalized mice. No difference in the motility of the small intestine was detected between germfree, gnotobiotic, and conventionalized mice.
The function of fimbriae in Myxococcus xanthus. II. The role of fimbriae in cell–cell interactions
Authors: Dobson W. J. , McCurdy H. D. , MacRae T. H.
Published: April 2010

Anti-fimbriae antiserum specifically inhibited swarming but not gliding motility per se in Myxococcus xanthus. However, formation of motile aggregates on agar and clumps in liquid media correlated with the presence of fimbriae. Ethylenediaminetetraacetic acid which inhibited swarming also inhibited fimbriae formation. Direct electron-microscopic observations revealed that fimbriae establish contact with apposing cell surfaces.Intact but not depolymerized fimbriae exhibited hemagglutination activity against guinea pig erythrocytes. This activity was inhibited by mannose, N-acetyl-D-galactosamine, and to a lesser degree by fructose, raffinose. melibiose, and α-methyl-D-mannoside.It is concluded that fimbriae are organelles which function to establish and maintain intercellular contacts, perhaps by a lectin-like function, during the coordinated movement of cell aggregates(swarming) in myxobacteria. This hypothesis is supported by the observations of other workers that genes determining movement of cells in groups also control fimbriation in M. xanthus.
Cellulose degradation by a new isolate from sewage sludge, a member of the Bacteroidaceae family
Authors: Saddler J. N. , Khan A. W.
Published: April 2010

A mesophilic anaerobe, a member of the Bacteroidaceae family (NRC2248), isolated from a cellulose-enrichment culture, digested untreated Whatman cellulose powder and HCl-treated cotton battings while producing hydrogen, carbon dioxide, cellobiose, glucose, and acetic acid as the sole volatile acid. This organism also utilized cellobiose as carbon and energy source but did not utilize glucose. It grew well in synthetic medium containing ammonium salts as nitrogen source and having a pH value of 7.0–7.1 and an Eh value of −160 mV or lower. The nutrient requirements of this organism were found to be similar to those of other anaerobes except for Na2S which inhibited cellulose degradation in concentrations above 0.75 mM. Best cellulose degradation occurred under an atmosphere of 80% N2–20% CO2. Use of H2 or 80% H2–20%CO2 as headspace gas inhibited growth. Although accumulation of acetic acid in about 15–16 mM concentrations inhibited the further formation of H2, CO2, and acetic acid in the broth, it did not stop the degradation of cellulose. The results indicate that this organism has the ability to grow in media containing up to 20 g/L of cellulose and to produce industrially important and easily separable end products from cellulose.
Moyen de prédire le pourcentage de dégradation de la fluorescence induite par impulsions de lumière lasérienne dans la technique d'immunofluorescence FTA-ABS
Authors: Lambert N. G. , Ste-Marie A. R.
Published: April 2010

The force, diameter, and pulse time of laser rays used in the FTA-ABS immunofluorescence technique permit us to calculate and to predict what the percentage of degradation of the emitted fluorescence will be for the operating conditions in which this degradation is produced. [Translated by the journal]
IMPROVED ALGORITHMS FOR UNSUPERVISED DISCRIMINANT PROJECTION
Authors: PARK CHEONG HEE
Published: April 2010

Dimension reduction has been applied in various areas of pattern recognition and data mining. While a traditional dimension reduction method, Principal Component Analysis (PCA) finds projective directions to maximize the global scatter in data, Locality Preserving Projection (LPP) pursues linear dimension reduction to minimize the local scatter. However, the discriminative power by either global or local scatter optimization is not guaranteed to be effective for classification. A recently proposed method, Unsupervised Discriminant Projection (UDP) aims to minimize the local scatter among near points and maximize the global scatter of distant points at the same time. Although its performance has been proven to be comparable to other dimension reduction methods, PCA preprocessing step due to the singularity of global and local scatter matrices may degrade the performance of UDP. In this paper, we propose several algorithms to improve the performances of UDP greatly. An improved algorithm for UDP is presented which applies the Generalized Singular Value Decomposition (GSVD) to overcome singularities of scatter matrices in UDP. Two-dimensional UDP and nonlinear extension of UDP are also proposed. Extensive experimental results demonstrate superiority of the proposed algorithms.
HOMOGENIZATION OF THE MAGNETO-RESISTANCE IN DIMENSION TWO
Authors: BRIANE MARC
Published: April 2010

A general formula for the effective magneto-resistance in a two-dimensional heterogeneous conductor submitted to a low magnetic field is given through H-convergence. In the periodic case, it is proved that the dissipation energy due to the effective magneto-resistance is greater than or equal to the average of the energy due to the local magneto-resistance, and that the equality holds if and only if the local Hall coefficient is constant. This agrees with an anisotropic extension of the Kohler law in the framework of the ordinary magneto-resistance. The result is illustrated by the case of a two-phase rank-one laminate.
ASPHERICAL SYMMETRIES OF GRAPH LINKS
Authors: IKEDA TORU
Published: April 2010

We will classify 2-component non-splittable graph links in S3, each of which is aspherically symmetric, i.e. the exterior admits a periodic homeomorphism which does not extend to a periodic homeomorphism of S3. They can be obtained from spherically symmetric graph links by one or two steps of specific types of iterated cabling. Some of them admit both orientation-preserving and orientation-reversing aspherical symmetries. We will study whether they admit Dehn surgeries which yield 3-manifolds with the induced double symmetries or not.
Composition, Structure, Dynamics, and Evolution of Saturn's Rings
Authors: Esposito Larry W.
Published: April 2010

Cassini observations confirm that Saturn's rings are predominantly water ice. The particles in Saturn's rings cover a range of sizes, from dust to small moons. Occultation results show the particles form temporary elongated aggregates tens of meters across. Some of the ring structure is created by moons, others by various instabilities. Data from future Cassini measurements can help investigators decide if the rings are remnants of the Saturn nebula or fragments of a destroyed moon or comet.
Oceanic Island Basalts and Mantle Plumes: The Geochemical Perspective
Authors: White William M.
Published: April 2010

Mantle plumes—which are usually, but not always, chemically distinct from the mid-ocean ridge basalt (MORB)—may be rooted in the core-mantle boundary and begin with large voluminous heads triggering massive eruptions or be headless and arise in the mid-mantle. Geochemistry provides convincing evidence that mantle plumes are 100–300°C hotter than normal upper mantle and that upwelling rates within the melting region are faster than beneath mid-ocean ridges. 186Os/188Os hints at the possibility of material from Earth's core in the Hawaiian plume, but this is not seen in other oceanic island basalt (OIB) and has not been confirmed by 182W/184W measurements. High 3He/4He in plumes does not require a primordial deep-mantle reservoir. The geochemical signature of mantle plumes originates primarily through melting in the upper mantle, probably through creation and subduction of oceanic lithosphere, but the details remain obscure. Plumes are lithologically heterogeneous, consisting of stringers of mafic material embedded in a more dominant peridotite.
The Origin(s) of Whales
Authors: Uhen Mark D.
Published: April 2010

Whales are first found in the fossil record approximately 52.5 million years ago (Mya) during the early Eocene in Indo-Pakistan. Our knowledge of early and middle Eocene whales has increased dramatically during the past three decades to the point where hypotheses of whale origins can be supported with a great deal of evidence from paleontology, anatomy, stratigraphy, and molecular biology. Fossils also provide preserved evidence of behavior and habitats, allowing the reconstruction of the modes of life of these semiaquatic animals during their transition from land to sea. Modern whales originated from ancient whales at or near the Eocene/Oligocene boundary, approximately 33.7 Mya. During the Oligocene, ancient whales coexisted with early baleen whales and early toothed whales. By the end of the Miocene, most modern families had originated, and most archaic forms had gone extinct. Whale diversity peaked in the late middle Miocene and fell thereafter toward the Recent, yielding our depauperate modern whale fauna.
Oblique, High-Angle, Listric-Reverse Faulting and Associated Development of Strain: The Wenchuan Earthquake of May 12, 2008, Sichuan, China
Authors: Zhang Pei-Zhen , Wen Xue-ze , Shen Zheng-Kang , Chen Jiu-hui
Published: April 2010

The 2008 Wenchuan earthquake occurred on imbricate, oblique, steeply dipping, slowly slipping, listric-reverse faults. Measurements of coseismic slip, the distribution of aftershocks, and fault-plane solution of the mainshock all confirm this style of deformation and indicate cascading earthquake rupture of multiple segments, each with coseismic slip occurring in the shallow crust above a depth range of 10 to 12 km. Interactions among three geological units—eastern Tibet, the Longmen Shan, and the Sichuan basin—caused slow strain accumulation in the Longmen Shan so that measurable preearthquake slip was minor. Coseismic deformation, however, took place mostly within the interseismically locked Longmen Shan fault zone. The earthquake may have initiated from slip on a fault plane dipping 30–40° northwest in a depth range from 15 to 20 km and triggered oblique slip on the high-angle faults at depths shallower than 15 km to form the great Wenchuan earthquake.
Frictional Melting Processes in Planetary Materials: From Hypervelocity Impact to Earthquakes
Authors: Spray John G.
Published: April 2010

Frictional melting is the result of the conversion of mechanical deformation to heat under adiabatic conditions of slip. Within planetary materials, which are mainly natural ceramics, frictional melting occurs at high strain rates (typically >10−2 s−1) and at slip velocities greater than 0.1 m s−1. The pathway to friction melting is controlled by the mechanical properties of a rock's constituent minerals, especially fracture toughness. Minerals with the lowest fracture toughnesses and breakdown temperatures are preferentially comminuted and fused to form the melt. The product is a polyphase suspension comprising mineral and rock fragments enclosed in a liquid matrix. This cools to form the rock type known as pseudotachylyte, and at even higher strain rates, it forms shock veins in meteorites and in impact craters, which may contain high-pressure mineral polymorphs. The generation of melt on sliding surfaces can lubricate earthquake faults, facilitate the post-shock modification of impact craters, and make landslides more hazardous.
Expression of cannabinoid CB1 receptors by vagal afferent neurons: kinetics and role in influencing neurochemical phenotype
Authors: Burdyga Galina , Varro Andrea , Dimaline Rod , Thompson David G. , Dockray Graham J.
Published: April 2010

The intestinal hormone cholecystokinin (CCK) inhibits food intake via stimulation of vagal afferent neurons (VAN). Recent studies suggest that CCK also regulates the expression of some G protein-coupled receptors and neuropeptide transmitters in these neurons. The aim of the present study was to characterize the expression of cannabinoid (CB)1 receptors in VAN and to determine whether stimulation of these receptors plays a role in regulating neurochemical phenotype. Expression of CB1 in rat VAN was detectable by in situ hybridization or immunohistochemistry after 6 h of fasting and increased to a maximum after 24 h when ∼50% of neurons in the mid and caudal regions expressed the receptor. Melanin-concentrating hormone (MCH)1 receptors also increased with fasting, but the changes were delayed compared with CB1; in contrast Y2 receptors (Y2R) exhibited reciprocal changes in expression to CB1. Administration of CCK8s (10 nmol ip) to fasted rats decreased expression of CB1 with a t1/2 of ∼1 h compared with 3 h for MCH1. The action of CCK8s was inhibited by ghrelin and orexin-A. The CB1 agonist anandamide (intraperitoneally) reversed the effect of CCK8s on CB1, MCH1, and Y2 receptor expression. In contrast, in rats fasted for 18 h, administration of a CB1 antagonist/inverse agonist (AM281 ip) downregulated CB1 expression and increased Y2 receptor expression. Activation of vagal CB1 receptors therefore influences the neurochemical phenotype of these neurons, indicating a new and hitherto unrecognized role for endocannabinoids in gut-brain signaling.
Resolvin E1 protects the rat heart against reperfusion injury
Authors: Keyes K. T. , Ye Y. , Lin Y. , Zhang C. , Perez-Polo J. R. , Gjorstrup P. , Birnbaum Y.
Published: April 2010

The purpose of the present study was to assess whether resolvin E1 (RvE1), an anti-inflammatory mediator derived from eicosapentaenoic acid, would limit myocardial infarct size in the rat. The H9c2 cell line was used to assess whether RvE1 has direct protective effects on cardiomyocytes. In in vivo experiments, Male Sprague-Dawley rats underwent 30 min of ischemia/4 h of reperfusion. Before reperfusion, rats received intravenous RvE1 (0, 0.03, 0.1, or 0.3mg/kg). In in vitro experiments, H9c2 cells were incubated with RvE1 (0, 1, 10, 100, or 1000 nM). Cells were subjected to 18 h of incubation under normoxic conditions, 16 h of hypoxia, or 16 h of hypoxia and 2 h of reoxygenation. In vivo, RvE1 dose dependently reduced infarct size (30.7 ± 1.7% of the area at risk in the control group and 29.1 ± 1.6%, 14.7 ± 1.3%, and 9.0 ± 0.6% in the 0.03, 0.1, and 0.3 mg/kg groups, respectively, P < 0.001). In vitro, RvE1 increased viability and decreased apoptosis in a dose-dependent fashion in cells exposed to hypoxia or hypoxia/reoxygenation. A maximal effect was achieved at a concentration of 100 nM. RvE1 augmented phosphoinositide 3-kinase activity, attenuated caspase-3 activity, and augmented calcium-dependent nitric oxide synthase activity in cells exposed to hypoxia or hypoxia/reoxygenation. RvE1 increased Akt, ERK1/2, and endothelial nitric oxide synthase phosphorylation and attenuated the levels of activated caspase-3 and phosphorylated p38 levels. AG-1478, an EGF receptor tyrosine kinase inhibitor, blocked the protective effect of RvE1 both in vivo and in vitro and attenuated the RvE1-induced increase in Akt and ERK1/2 phosphorylation. In conclusion, RvE1, an anti-inflammatory mediator derived from eicosapentaenoic acid, has a direct protective effect on cardiomyocytes against ischemia-reperfusion injury and limits infarct size when administered intravenously before reperfusion.
Effects of normoxic and hypoxic exercise regimens on cardiac, muscular, and cerebral hemodynamics suppressed by severe hypoxia in humans
Authors: Wang Jong-Shyan , Wu Min-Huan , Mao Tso-Yen , Fu Tieh-cheng , Hsu Chih-Chin
Published: April 2010

Hypoxic preconditioning prevents cerebrovascular/cardiovascular disorders by increasing resistance to acute ischemic stress, but severe hypoxic exposure disturbs vascular hemodynamics. This study compared how various exercise regimens with/without hypoxia affect hemodynamics and oxygenation in cardiac, muscle, and cerebral tissues during severe hypoxic exposure. Sixty sedentary males were randomly divided into five groups. Each group ( n = 12) received one of five interventions: 1) normoxic (21% O2) resting control, 2) hypoxic (15% O2) resting control, 3) normoxic exercise (50% maximum work rate under 21% O2; N-E group), 4) hypoxic-relative exercise (50% maximal heart rate reserve under 15% O2; H-RE group), or 5) hypoxic-absolute exercise (50% maximum work rate under 15% O2; H-AE group) for 30 min/day, 5 days/wk, for 4 wk. A recently developed noninvasive bioreactance device was used to measure cardiac hemodynamics, and near-infrared spectroscopy was used to assess perfusion and oxygenation in the vastus lateralis (VL)/gastrocnemius (GN) muscles and frontal cerebral lobe (FC). Our results demonstrated that the H-AE group had a larger improvement in aerobic capacity compared with the N-E group. Both H-RE and H-AE ameliorated the suppression of cardiac stroke volume and the GN hyperemic response (Δtotal Hb/min) and reoxygenation rate by acute 12% O2exposure. Simultaneously, the two hypoxic interventions enhanced perfusion (Δtotal Hb) and O2extraction [ΔdeoxyHb] of the VL muscle during the 12% O2exercise. Although acute 12% O2exercise decreased oxygenation (ΔO2Hb) of the FC, none of the 4-wk interventions influenced the cerebral perfusion and oxygenation during normoxic/hypoxic exercise tests. Therefore, we conclude that moderate hypoxic exercise training improves cardiopulmonary fitness and increases resistance to disturbance of cardiac hemodynamics by severe hypoxia, concurrence with enhancing O2delivery/utilization in skeletal muscles but not cerebral tissues.
Site-specific effects on respiratory rhythm and pattern of ibotenic acid injections in the pontine respiratory group of goats
Authors: Bonis J. M. , Neumueller S. E. , Krause K. L. , Kiner T. , Smith A. , Marshall B. D. , Qian B. , Pan L. G. , Forster H. V.
Published: April 2010

To probe further the contributions of the rostral pons to eupneic respiratory rhythm and pattern, we tested the hypothesis that ibotenic acid (IA) injections in the pontine respiratory group (PRG) would disrupt eupneic respiratory rhythm and pattern in a site- and state-specific manner. In 15 goats, cannulas were bilaterally implanted into the rostral pontine tegmental nuclei (RPTN; n = 3), the lateral (LPBN; n = 4) or medial parabrachial nuclei (MPBN; n = 4), or the Kölliker-Fuse nucleus (KFN; n = 4). After recovery from surgery, 1- and 10-μl injections (1 wk apart) of IA were made bilaterally through the implanted cannulas during the day. Over the first 5 h after the injections, there were site-specific ventilatory effects, with increased ( P < 0.05) breathing frequency in RPTN-injected goats, increased ( P < 0.05) pulmonary ventilation (V̇i) in LPBN-injected goats, no effect ( P < 0.05) in MPBN-injected goats, and a biphasic V̇i response ( P < 0.05) in KFN-injected goats. This biphasic response consisted of a hyperpnea for 30 min, followed by a prolonged hypopnea and hypoventilation with marked apneas, apneusis-like breathing patterns, and/or shifts in the temporal relationships between inspiratory flow and diaphragm activity. In the awake state, 10–15 h after the 1-μl injections, the number of apneas was greater ( P < 0.05) than during other studies at night. However, there were no incidences of terminal apneas. Breathing rhythm and pattern were normal 22 h after the injections. Subsequent histological analysis revealed that for goats with cannulas implanted into the KFN, there were nearly 50% fewer neurons ( P < 0.05) in all three PRG subnuclei than in control goats. We conclude that in awake goats, 1) IA injections into the PRG have site-specific effects on breathing, and 2) the KFN contributes to eupneic respiratory pattern generation.