bluuebunny/crossref_metadata_2025 huggingface dataset:
Ribosomal proteins in halobacteria
Authors: Kimura Makoto , Arndt Evelyn , Hatakeyama Tomomitsu , Hatakeyama Tamiko , Kimura Junko
Published: November 2009

The amino acid sequences of 16 ribosomal proteins from archaebacterium Halobacterium marismortui have been determined by a direct protein chemical method. In addition, amino acid sequences of three proteins, S11, S18, and L25, have been established by DNA sequencing of their genes as well as by protein sequencing. Comparison of their sequences with those of ribosomal proteins from other organisms revealed that proteins S14, S16, S19, and L25 are related to both eukaryotic and eubacterial ribosomal proteins, being more homologous to eukaryotic than eubacterial counterparts, and proteins S12, S15, and L16 are related to only eukaryotic ribosomal proteins. Furthermore, some proteins are found to be similar to only eubacterial proteins, whereas other proteins show no homology to any other known ribosomal proteins. Comparisons of amino acid compositions between halophilic and nonhalophilic ribosomal proteins revealed that halophilic proteins gain asparatic and glutamic acid residues and significantly lose lysine and arginine residues. In addition, halophilic proteins seem to lose isoleucine as compared with Escherichia coli ribosomal proteins.Key words: halobacteria, ribosomal proteins, amino acid sequence.
The effects of amphotericin B on the interaction of Candida albicans with fibroblast cultures
Authors: Merkel Glenn J. , Phelps Charles L.
Published: November 2009

Sublethal amounts of amphotericin B inhibited the interaction of Candida albicans with cultured fibroblasts. Different C. albicans clinical isolates exhibited varying degrees of sensitivity to the drug, but those isolates that were the most infective in control cultures appeared to be the most resistant to amphotericin B mediated infection inhibition. Although amphotericin B inhibited germ tube formation at the sublethal concentration of 0.3 μg/mL, lower concentrations inhibited infection without preventing germination. The extent of this latter activity varied with the isolate and amphotericin B concentration and appeared to be related to sublethal effects on germinated yeasts. While amphotericin B effectively prevented new fibroblast infection, it did not dissociate those yeasts which had established an infection before its addition.Key words: yeast, Candida, amphotericin B, polyene antibiotics.
Conditions affecting the amphotericin B mediated inhibition of Candida albicans attachment to cell cultures
Authors: Merkel Glenn J. , Phelps Charles L.
Published: November 2009

Sublethal amounts of amphotericin B inhibited the attachment of Candida albicans to cultured mammalian cells. The extent of inhibition was influenced by the concentration of serum and the growth phase of the yeasts used to inoculate the cell cultures. Yeasts which were in their exponential phase of growth or had formed germ tubes were the most sensitive to amphotericin B. Equivalent amounts of amphotericin B inhibited yeast – mammalian cell interactions to different degrees depending upon the culture's tissue origin.Key words: Candida, amphotericin, polyenes, attachment, yeasts.
Characterization of cross-reacting serotypes of Campylobacter jejuni
Authors: Preston Martin A. , Penner J. L.
Published: November 2009

Some strains of Campylobacter jejuni react with more than one reference antiserum from the serotyping scheme based on heat-stable lipopolysaccharide antigens. To investigate the molecular basis of these cross-reactions, lipopolysaccharides from the reference strains for serotypes 4, 13, 16, 43, and 50 and isolates recovered during two different outbreaks of C. jejuni enteritis were analyzed by passive haemagglutination and sodium dodecyl sulphate – polyacrylamide gel electrophoresis coupled with silver staining or immunoblotting. The results showed that lipopolysaccharides from the reference strains and the isolates reacted with antisera prepared against heterologous strains in various combinations and that both silver-stainable, low Mr and non-silver-stainable, high Mr lipopolysaccharide components provided the antigenic determinants associated with the cross-reactions. There were strain-to-strain differences in the structural and antigenic properties of these macromolecules and shared antigenic determinants were not always provided by a common structure. Analysis of the silver-stained lipopolysaccharide profiles, outer membrane protein patterns, and chromosomal DNA restriction patterns indicated that strains with the same lipopolysaccharide profile could have the same outer membrane protein pattern and the same DNA restriction pattern. These results provided evidence for the presence of clones within this antigenic complex and implicated antigenic variation in some strains as the phenomenon responsible for the multiplicity of cross-reactions.Key words: Campylobacter, serotypes, cross-reaction.
The characterization and ultrastructure of two new strains of Butyrivibrio
Authors: Cheng K.-J. , Phillippe R. C. , McLean R. J. C. , Costerton J. W.
Published: November 2009

Strains B-385-1 and 2-33 are numerically important components of rumen bacterial populations, but they have remained (taxonomically) undefined. In spite of some resemblance to Selenomonas ruminantium in their cell size and in their formation of tufts of flagella, they more closely resemble Butyrivibrio fibrisolvens in the subpolar location of their flagella, in their guanine + cytosine content, and in most biochemical characteristics, including butyrate formation. Cells of these strains stain Gram negative, as do both Selenomonas and Butyrivibrio, but their cell walls closely resemble those of Butyrivibrio in their Gram-positive type of molecular architecture and in their cleavage pattern in freeze-etching. Cells of these strains and of B. fibrisolvens have a very thin (ca. 12 nm) peptidoglycan cell wall; thus, they fail to retian the crystal violet complex of the Gram stain and stain Gram negative. This important structural characteristic of their cell walls places strains B-385-1 and 2-33 within the genus Butyrivibrio and certain morphological and biochemical characteristics distinguish them from B. fibrisolvens.Key words: Butyrivibrio, characterization, ultrastructure.
The use of metronidazole to study pyridine nucleotide reduction in vivo in Azotobacter vinelandii
Authors: Peterson Jay B.
Published: November 2009

Flavins of the particulate and supernatant fractions from nitrogen-fixing Azotobacter vinelandii cells were examined by fluorescence spectroscopy for reduction by NAD(P)H in the absence and presence of the low potential electron acceptor metronidazole. The objective was to determine if reduction of metronidazole-oxidized flavin in vivo results from NAD(P)H generation. Flavin was almost completely reduced by NADH, but NADPH gave less reduction. Most of the flavin was reduced in the presence of metronidazole. Menadione bisulfite prevented reduction. In whole-cell studies, mannitol-generated NAD(P)H reduced flavin in the presence of menadione bisulfite. These results establish that reduction of metronidazole-oxidized cell flavin in vivo is an indicator of NAD(P)H production.Key words: metronidazole, NAD(P)H reduction, Azotobacter vinelandii.
A comparison of the three dinitrogenase reductases expressed by Azotobacter vinelandii
Authors: Premakumar R. , Chisnell John R. , Bishop Paul E.
Published: November 2009

Dinitrogenase reductase-2 was purified from Azotobacter vinelandii under conditions used for the purification of nitrogenase-3 and was compared with dinitrogenase reductases-1 and -3 from A. vinelandii. Dinitrogenase reductase-2 was a dimer with a subunit Mr of 34 000 Da. It contained 4 Fe and 4 acid-labile S2− per molecule. The specific activities (acetylene reduction) of dinitrogenase-1 with dinitrogenase reductase-2 and dinitrogenase reductase-3 were found to be 58 and 0.8% of that with dinitrogenase reductase-1, respectively. The dinitrogenase reductases were found to be antigenically similar in an immunodiffusion experiment using anti-dinitrogenase reductase-1 serum. Peptide mapping of the dinitrogenase reductases suggested that there was greater amino acid sequence homology between dinitrogenase reductases-1 and -2 (81%) than between dinitrogenase reductases-1 and -3 (50%).Key words: nitrogenase, Azotobacter, dinitrogenase reductases.
Isolation and characterization of cadmium-resistant mutants of Neurospora crassa
Authors: Levine Wendy B. , Marzluf George A.
Published: November 2009

This study identified and characterized four cadmium-resistant mutants of Neurospora crassa. One of these mutants maps to linkage group II and the other three map to linkage group VII, whereas a naturally occurring resistant trait in a strain from Japan resides at a distinct but unmapped locus. Transport of cadmium into Neurospora cells occurs by more than a single uptake system and involves both energy-dependent and -independent components. The resistant mutants transport cadmium in the same manner as does the cadmium-sensitive wild-type strain. Cadmium resistance in these mutants does not appear to result from an increase in cytosolic heat-stable cadmium-binding proteins. Cadmium does not induce the typical heat-shock response in conidia. Under various growth conditions, each of the mutants exhibited morphological alterations, possibly involving the cell wall or plasma membrane.Key words: cadmium, Neurospora, transport, resistant mutants.
Stage-specific changes in cytoplasmic protein synthesis in Entomophaga aulicae protoplasts
Authors: Nolan Richard A.
Published: November 2009

The patterns of protein synthesis associated with three sequential stages in protoplast morphogenesis (spindle-shaped, early fusion sphere, and late fusion sphere protoplasts) of the fungus Entomophaga aulicae were studied using both one-dimensional gels with general protein staining and two-dimensional gels with [35S]methionine protein labelling and fluorography. A total of 332 proteins were observed with 63.5% (211) common to all three developmental stages. Of the individual totals, 3.3% (8 out of 245), 7.3% (22 out of 301), and 4.5% (13 out of 286) of the proteins were unique to the spindle-shaped, early fusion sphere, and late fusion sphere protoplasts, respectively. The molecular mass and pI distribution profiles for early fusion sphere protoplast proteins are discussed.Key words: protein synthesis, stage-specific proteins, fungal protoplasts, Entomophaga aulicae.
Influence of prior growth conditions on low nutrient response of Escherichia coli in seawater
Authors: Gauthier Michel J. , Munro Patrick M. , Breittmayer Violette A.
Published: November 2009

By use of experimental microcosms, it was demonstrated that the survival of Escherichia coli in nutrient-free seawater depended on the age of cells and on some physicochemical conditions during their prior growth. Cells grown in a bacteriological medium, with an acid or an alkaline pH, at high temperature (44 °C), or in the absence of oxygen were more sensitive to exposure to seawater of low nutrient content. In contrast, some complex media allowed production of cells adapting more rapidly to seawater. Cells grown in urine were far more sensitive than those grown in all bacteriological media tested. The sensitivity of all cells was highest when they were harvested during the early exponential phase of growth.Key words: Escherichia coli, seawater, growth, survival.
Development of the cellulolytic microflora in the rumen of lambs transferred into sterile isolators a few days after birth
Authors: Fonty G. , Gouet P. , Nebout J. M.
Published: November 2009

Seven lambs, separated from their dam 24 h after birth, were kept in a conventional environment until transferred to sterile isolators between 1 and 9 days of age: two on day 1 (IA and IB), two on day 4 (IVA and IVB), one on day 8 (VIIIA), and two on day 9 (IXA and IXB). The lambs were reared in these isolators until 120 days of age. Lambs IA, IB, IXA, and IXB were free of cellulolytic bacteria when they were placed in the isolators. They were then inoculated with Bacteroides succinogenes S85 which became established in the four lambs. Until the age of 2 months, the population of this strain fluctuated and then stabilized at a high level (108–109 cells/mL). Cellulolytic bacteria were present in the rumen of lambs IVA, IVB, and VIIIA when they were transferred to the isolators. In IVA, and IVB, the cellulolytic population slowly increased with the animal age. In contrast, in VIIIA, the cellulolytic bacteria disappeared within a few days. Bacteroides succinogenes S85 inoculated thereafter became established rapidly and reached a level comparable to that observed in lambs IA and IB. The total number of viable rumen bacteria in the isolated lambs was similar to that observed in conventionally raised animals, but differences were observed in the selective enumeration of bacteria utilizing specific energy sources.Key words: rumen, isolated lambs, cellulolytic bacteria.
The use of Tween 20 in a sensitive turbidimetric assay of lipolytic enzymes
Authors: Tigerstrom Richard G. von , Stelmaschuk Sheilah
Published: November 2009

A turbidimetric esterase assay was developed using a Tween 20 solution in the presence of CaCl2 and Lysobacter enzymogenes esterase (EC 3.1.1.1) as the enzyme source. The reaction was followed by measuring the increase in the optical density at 500 nm (OD500) due to the hydrolytic release of the fatty acids from Tween 20 and their precipitation as the calcium salts. Concentrations of 1.8% Tween and 3 mM CaCl2 were found to be optimal for the assay of 0.036 to 0.15 esterase units in a 4-mL reaction mixture over a 30-min period. The esterase reactions were linear with time at least up to 1.2 OD500 and die rate of increase in the ODS00 was proportional to the enzyme concentration. Low initial reaction rates were seen with low esterase activity, presumably because of the limited solubility of the fatty acid – calcium salt in a 1.8% Tween solution. This turbidimetric method is much simpler and at least 36 times more sensitive than the titrimetric assay with Tween 20, and at least four times more sensitive than a spectrophotometric assay with p-nitrophenyl palmitate. This assay has been used to determine the activities of cell-associated and excreted esterases produced by Lysobacter enzymogenes and Pseudomonas aeruginosa, and of lipolytic enzymes from porcine liver, Chromobacterium viscosum, Candida cylindracea, and wheat germ.Key words: esterase, lipase, Tween detergents, Lysobacter.
Adenine salvage enzymes and intracellular nucleotide triphosphate content in Physarum flavicomum amoebae during growth and development
Authors: Cumaraswamy Arunthathi , Henney Jr. Henry R.
Published: November 2009

The specific activity of adenine phosphoribosyltransferase (APRT) (EC 2.4.2.7) and adenosine phosphorylase (EC 2.4.2.-), two enzymes involved in the utilization of exogenous adenine, was measured in extracts of myxamoebae-swarm cells of Physarum flavicomum undergoing growth, microcyst formation (control), and during adenine inhibition of encystment. Both enzymes showed a higher specific activity in adenine-inhibited cells (AIC) compared to normal control (NC) or growing cells (GC). These experiments revealed that the specific activity of APRT was 7.1-, 5.3-, and 1.7-fold higher than that of adenosine phosphorylase in AIC, GC, and NC, respectively. This suggests a predominant role for the enzyme APRT in the salvage of adenine in this organism. The major route for the utilization of adenine thus seems to be by its direct conversion to AMP rather than via its riboside adenosine. HPLC analysis of the ribonucleotide triphosphates in cell extracts of GC, NC, and AIC revealed a 2.6- and a 3.3-fold increase in the ATP and GTP content, respectively, in the AIC compared with the NC cells. The ATP content in the GC was higher by a factor of 2.2 compared with the NC cells, while the GTP content in the GC was only 0.6 times that in the NC cells. UTP levels in AIC and GC were 1.3- and 1.4-fold higher than in the NC cells. In contrast, the CTP level in AIC was lower than in NC cells and was not detectable in the growing cells.Key words: adenine phosphoribosyltransferase, ATP, GTP, amoebae, Physarum.
Morphology and fine structure of the trophozoites of Theratromyxa weberi (Protozoa: Vampyrellidae) predacious on soil nematodes
Authors: Sayre Richard M. , Wergin William P.
Published: November 2009

Trophozoites of Theratromyxa weberi, a vampyrellid amoeba, were reared on prey nematodes, Aphelenchoides rutgersi. The early stages of contact and encystment were observed with light, scanning, and transmission microscopy. Light microscopy revealed that the amoebae appeared to envelop their prey with a continuous multinucleate protoplast in less than 3 h. However, when this process was observed with scanning electron microscopy, the trophozoites appeared as numerous interwoven protoplasmic strands that systematically contacted, covered, and enfolded the nematode larvae. Only after total engulfment did the strands of the amoeba coalesce to form a continuous membrane around the nematode. Transmission electron microscopy revealed the presence of numerous organelles typical of eukaryotes. Nuclei, mitochondria, and particulate helices were the predominant organelles present during the contact stage whereas lipid bodies, lysosomes, and osmiophilic bodies predominated during the formation of the digestive cyst.Key words: fine structure, soil amoeba, plant-parasitic nematodes, soil ecology, biological control.
Interaction between hydrogenase, nitrogenase, and respiratory activities in a Frankia isolate from Alnus rubra
Authors: Murry Marcia A. , Lopez Mary F.
Published: November 2009

H2 uptake and H2-supported O2 uptake were measured in N2-fixing cultures of Frankia strain ArI3 isolated from root nodules of Alnus rubra. H2 uptake by intact cells was O2 dependent and maximum rates were observed at ambient O2 concentrations. No hydrogenase activity could be detected in [Formula: see text], undifferentiated filaments cultured aerobically indicating that uptake hydrogenase activity was associated with the vesicles, the cellular site of nitrogen fixation in Frankia. Hydrogenase activity was inhibited by acetylene but inhibition could be alleviated by pretreatment with H2. H2 stimulated acetylene reduction at supraoptimal but not suboptimal O2 concentrations. These results suggest that uptake hydrogenase activity in ArI3 may play a role in O2 protection of nitrogenase, especially under conditions of carbon limitation.Key words: Frankia, hydrogenase, nitrogenase, O2 protection.
Populations of Rhizobium leguminosarum biovars phaseoli and viceae in fields after bean or pea in rotation with nonlegumes
Authors: Kucey R. M. N. , Hynes M. F.
Published: November 2009

Populations of Rhizobium leguminosarum bv. phaesoli and bv. viceae in southern Alberta soils were measured over a period of 4 years using a most probable number method. Five fields cropped to bean (Phaseolus vulgaris L.), five fields cropped to pea (Pisum sativum L.), and two fields cropped to wheat were used as test sites. Legume crops had received appropriate legume inoculants. Fields were sampled in the fall of the crop year and in the spring of the following 3 years during which fields were cropped to nonlegumes or left fallow. Numbers of R. leguminosarum bv. phaseoli were 100 to 1000 times higher in fields that had been planted to bean than in fields that had been planted to pea or wheat. Fields that had been planted to pea maintained populations of R. leguminosarum bv. viceae 10 to 100 times higher than fields that had been planted to bean or wheat. Wheat fields, which had never had legumes grown in them, contained between 1 and 100 rhizobia per gram of soil of both biovars of R. leguminosarum, indicating that both biovars are native to southern Alberta soils. The numbers of rhizobia did not decrease in proportion to the population of other bacteria in the soil over the duration of the experiment. Plasmid profiles of soil Rhizobium isolates obtained in the last year of the experiment showed that none of the isolates had plasmid profiles similar to those of strains added as inoculants in the 1st year of the experiment. These results show that fields cropped to legumes and receiving rhizobial inoculants in this study maintained high populations of rhizobia for several years after harvest of the legume crop.Key words: Rhizobium leguminosarum bv. phaseoli, Rhizobium leguminosarum bv. viceae, nodule, plasmid profiles, inoculum potential, rhizobium competition.
Survival of and plasmid stability in Pseudomonas and Klebsiella spp. introduced into agricultural drainage water
Authors: Trevors J. T. , Elsas J. D. Van , Starodub M. E. , Overbeek L. S. Van
Published: November 2009

Cell survival and plasmid stability in Pseudomonas fluorescens R2f and Pseudomonas putida CYM 318 containing respectively, plasmid RP4 and pRK2501, and Klebsiella aerogenes NCTC 418 harboring plasmid pBR322 were studied in sterile and nonsterile agricultural drainage water under both aerobic and anaerobic conditions and in the absence and presence of added nutrients. Both Pseudomonas strains survived well in sterile drainage water incubated aerobically, with or without added nutrients. However, Klebsiella aerogenes NCTC 418 (pBR322) only survived in the presence of added nutrients. Pseudomonas fluorescens R2f (RP4) and K. aerogenes NCTC 418 (pBR322) did not survive under anerobic conditions without added nutrients, but showed good survival in the presence of nutrients. Survival of all three strains was negatively affected in nonsterile agricultural drainage water when compared with survival in sterile water. Maintenance of the three plasmids was host, plasmid, and environment dependent. Plasmid pBR322 was not stably maintained in K. aerogenes NCTC 418 under all conditions used in the study, and pRK2501 was readily lost from P. putida CYM 318. Maintenance of RP4 by P. fluorescens R2f was markedly influenced by added nutrients, which caused a loss of the plasmid from cells. The results of the present study demonstrate the influence of nutrients, O2, and native microorganisms on the survival of introduced bacterial strains and plasmid stability in agricultural drainage water.Key words: bacteria, survival, stability, plasmids, water.
Changes in proton efflux of intact wheat roots induced by Azospirillum brasilense Cd
Authors: Bashan Yoav , Levanony Hanna , Mitiku Girma
Published: November 2009

Inoculation of wheat seedings with Azospirillum brasilense Cd increased proton efflux from the roots. Inoculation of seeds or young seedlings using bacterial cultures at the logarithmic phase of growth caused the strongest proton extrusion. The increased effect lasted up to 20 h. No difference was detected between inoculated and noninoculated plants 20 h after inoculation. Both inoculated and noninoculated plants decreased the final pH of the nutrient solution to 3.2 and had an average proton extrusion of 4.3 μmol H+ ∙ (g fresh weight)−1∙h−1. Azospirillum brasilense Cd inoculation of wheat roots in which proton efflux was inhibited by the addition of either nitrate, dicyclohexylcarbodiimide, or orthovanadate resulted in partial recovery of proton efflux activity in these roots. Inoculation of wheat seedlings also changed the regular pattern of root proton efflux over prolonged periods of time. It is suggested that A. brasilense Cd inoculation influenced membrane activity and subsequent proton efflux in roots of wheat seedlings.Key words: Azospirillum, plant–bacteria interaction, proton efflux, rhizosphere bacteria, Triticum aestivum, wheat.
Characterization of the biocontrol activity of Debaryomyces hansenii in the control of Penicillium digitatum on grapefruit
Authors: Droby S. , Chalutz E. , Wilson C. L. , Wisniewski M.
Published: November 2009

Interactions between Debaryomyces hansenii and Penicillium digitatum were studied in culture and on fruit to better characterize the observed biological control of green mold on grapefruit by the yeast. The antagonist did not produce antibiotic substances in culture and was ineffective in protecting against the disease when killed by heat or chemicals. Incidence of green mold was dependent upon the concentration of both the pathogen spores and the antagonist yeast cells. Control of green mold was most effective at 109 cfu/mL of D. hansenii. The role of available nutrients in the biological control activity of D. hansenii was assessed. Significant inhibition of spore germination and hyphal growth of P. digitatum in culture was achieved by the addition of the yeast cells to a minimal synthetic growth medium. Inhibition of P. digitatum by the antagonist in culture and on the fruit peel could be overcome by the addition of exogenous nutrients. Our results indicate that competition for nutrients may play a role in the biocontrol of P. digitatum by D. hansenii on grapefruit.Key words: biological control, Penicillium digitatum, Debaryomyces hansenii, grapefruit.
The apparent infection of NA-C1300 cell cultures by nucleocapsid material of the Canadian Arctic strain of rabies virus
Authors: Webster W. A. , Charlton K. M.
Published: November 2009

Murine neuroblastoma (NA-C1300) and baby hamster kidney (BHK-21/C13) cell cultures were infected with the Canadian Arctic strain of rabies virus. Subcultures were passed following incubation for 3 to 4 days at 35 °C. The supernatant fluids from the BHK cultures demonstrated increasing infectivity in both NA and BHK cells concomitantly with an increase in the number of parent cells staining with an anti-glycoprotein stain. On the other hand, the supernatant fluids from the NA cultures initially showed higher infectivity in NA cells than in BHK cells. This feature was related to a low production of glycoprotein-staining cells in the parent NA cultures. The reduction of infectivity in NA cells of some NA supernatant fluids (and brain suspensions) by anti-nucleoprotein antibodies suggests that nucleocapsid material is, in some manner, capable of infecting NA cells. Infectivity of this virus strain in experimental mice is also related to the production of glycoprotein and may not be correlated with the degree of infection in NA cell cultures.Key words: rabies, nucleocapsid, infection, cells.
Correlation of enhanced surfactin production with decreased isocitrate dehydrogenase activity
Authors: Roubin Marie-Renée de , Mulligan Catherine N. , Gibbs Bernard F.
Published: November 2009

The activity of an enzyme in the tricarboxylic acid cycle, isocitrate dehydrogenase EC 1.1.1.42 (ICD), was followed during the production of a biosurfactant, surfactin, by Bacillus subtilis. A mutant suppressed the activity of the enzyme 30 times more than the parent strain and simultaneously produced three and a half times more surfactin. Decreased ICD activity could also be achieved by (i) decreased oxygen concentration, (ii) increased growth rates, and the addition of (iii) citric acid or (iv) ammonium nitrate to the production medium. The nitrogen source (namely, ammonium nitrate) was critical as neither ammonium chloride nor sodium nitrate could individually enhance biosurfactant production. Initiation of surfactin production occurred as redox values increased and ICD activity decreased. Increased surfactin yields correlated with low levels of ICD activity.Key words: biosurfactant, surfactin, Bacillus subtilis, isocitrate dehydrogenase, mutant.
Effects of iron binding agents on Saccharomyces cerevisiae growth and cytochrome P450 content
Authors: Wright Gerard D. , Honek John F.
Published: November 2009

The yeast Saccharomyces cerevisiae Y222 was studied in the presence of the following iron-binding agents: Desferal, dipyridyl, and human and bovine transferrins. We report that cell growth and lanosterol 14 α-demethylase cytochrome P450 are not affected by Desferal but that dipyridyl and serum transferrins decrease the cytochrome P450 content of the yeast. Paradoxically, while both human and bovine transferrins reduce cytochrome P450 content, only bovine transferrin appears to affect cell growth in this strain. No evidence for siderophore production by this strain was found under low iron conditions.Key words: Saccharomyces cerevisiae, iron, cytochrome P450, transferrin.
Use of a bacteriophage-encoded glycanase enzyme in the generation of lipopolysaccharide O side chain deficient mutants of Escherichia coli O9:K30 and Klebsiella O1:K20: role of O and K antigens in resistance to complement-mediated serum killing
Authors: McCallum Kirk L. , Laakso Dayle H. , Whitfield Chris
Published: November 2009

Coliphage K30 lysates contain free and phage-associated forms of a bacteriophage-encoded capsule depolymerase (glycanase) enzyme, active against the serotype K30 capsular polysaccharide of Escherichia coli. The free glycanase has been purified to apparent homogeneity. The molecular weight of the enzyme was estimated at 450 000, and when heated in SDS at 100 °C, the enzyme dissociated into two subunits of 90 000 and 52 000. The glycanase enzyme was used as a reagent to reversibly degrade the capsular layers on cells of Escherichia coli O9:K30 and Klebsiella O1:K20. This treatment rendered these bacteria sensitive to their respective lipopolysaccharide-specific bacteriophages, coliphage O9-1 and Klebsiella phage O1-3. This novel approach facilitated isolation of lipopolysaccharide O antigen side chain deficient mutants which retained the ability to synthesize the capsule. The response of defined mutants, O+:K−, O−:K+, and O−:K−, to exposure to nonimmune rabbit serum was measured. Results showed that the primary barrier against complement-mediated serum killing in both Esherichia coli O9:K30 and Klebsiella O1:K20 was the O antigen side chains of the lipopolysaccharide molecules. In both strains, the capsule played no role in the determination of serum resistance.Key words: bacteriophage, glycanase, lipopolysaccharide, serum resistance, capsular polysaccharide.
Isolation of marine bacteria with antiviral properties
Authors: Girones Rosina , Jofre Juan T. , Bosch Albert
Published: November 2009

We report in this study the isolation of marine bacteria with antiviral properties that have been tentatively classified as Moraxella. These bacteria retained their virucidal capacity after prolonged subcultivation in the laboratory. The virus-inactivating agent could not be separated from the viable marine bacteria, indicating that the active agent(s) either remains associated to the microorganisms or has a very short lifetime, or both. The antiviral capacity of the isolated microorganisms was highly specific for poliovirus. No virucidal effect was observed against other strains of enteroviruses, such as Coxsackie and ECHO virus, rotavirus SA11, or bacteriophages proposed as indicators of the virological quality of water, such as coliphage f2 and bacteriophage B40-8, which infects Bacteroides fragilis.Key words: enterovirus, rotavirus, coliphages, bacteriophages, seawater, marine bacteria, antiviral activity, virus survival.
Bacterial colonization of domestic reverse-osmosis water filtration units
Authors: Payment Pierre
Published: November 2009

We have analyzed the bacterial content of water from the reservoirs of 300 reverse-osmosis units installed in households. The heterotrophic plate counts on R2A medium (20 and 35 °C) ranged from 0 to 107 colony forming units per millilitre (cfu/mL). Most reservoirs contained water with bacterial counts between 104 and 105 cfu/mL. The bacteria identified were Pseudomonas (not aeruginosa), Alcaligenes or Moraxella, Acinetobacter, Flavobacterium, and Chromobacterium. This report emphasizes the importance of bacterial colonization by heterotrophic bacteria in water reservoirs from domestic reverse-osmosis units.Key words: drinking water, bacteria, reverse-osmosis filter, regrowth.
Use of electron microscopy to characterize the surfaces of flocculent and nonflocculent yeast cells
Authors: Johnson Byron F. , Sowden L. C. , Walker Teena , Yoo Bong Y. , Calleja Gode B.
Published: November 2009

The surfaces of flocculent and nonflocculent yeast cells have been examined by electron microscopy. Nonextractive preparative procedures for scanning electron microscopy allow comparison in which sharp or softened images of surface details (scars, etc.) are the criteria for relative abundance of flocculum material. Asexually flocculent budding-yeast cells cannot be distinguished from nonflocculent budding-yeast cells in scanning electron micrographs because the scar details of both are well resolved, being hard and sharp. On the other hand, flocculent fission-yeast cells are readily distinguished from nonflocculent cells because fission scars are mostly soft or obscured on flocculent cells, but sharp on nonflocculent cells. Sexually and asexually flocculent fission-yeast cells cannot be distinguished from one another as both are heavily clad in "mucilaginous" or "hairy" coverings. Examination of lightly extracted and heavily extracted flocculent fission-yeast cells by transmission electron microscopy provides micrographs consistent with the scanning electron micrographs.Key words: flocculation, budding yeast, fission yeast, scanning, transmission.
Polymorphisms in the nuclear DNA of Achlya species: some taxonomic implications
Authors: Horton J. Stephen , Horgen Paul A.
Published: November 2009

Within the genus Achyla, which belongs to the class of fungi known as the Oomycetes, taxonomic judgments have traditionally been made using a variety of sexual criteria. We have used restriction fragment length polymorphisms as a new taxonomic character to examine intra- and inter-specific variation within this genus. Using a cDNA clone coding for the Achlya 18S rRNA gene as a hybridization probe, a 10-kb fragment of ribosomal DNA (rDNA) from Achlya ambisexualis strain E87 was cloned and then mapped for selected restriction enzyme sites. In Southern blot hybridizations, both this rDNA fragment and cloned 18S cDNAs revealed differences in the rDNA organization of A. ambisexualis E87 (male) and a female isolate of A. ambisexualis strain 734. No differences in the rDNAs were detected between the two heterothallic isolates A. ambisexualis E87 and A. bisexualis 65-1. Southern blot hybridizations suggested that two different rDNA organizations may exist within the genome of the homothallic strain A. heterosexualis B14. cDNA clones coding for two different hormonally regulated genes revealed the same relationships between the four isolates studied as those determined with rDNA probes. Two homothallic Achlya strains recently isolated from nature were found to have additional DNA polymorphisms not detected in the laboratory strains. Phenetic analysis distinguished the same similarities that were evident upon inspection of the hybridization data. Taken together, these data suggest different relationships between the isolates examined than do the previous taxonomic criteria by which species have been delimited within this genus.Key words: Achlya; restriction fragment length polymorphisms; ribosomal DNA; taxonomy.
A NOTE ON CONSTANT CURVATURE SOLUTIONS IN CYLINDRICALLY SYMMETRIC METRIC f(R) GRAVITY
Authors: MOMENI D. , GHOLIZADE H.
Published: November 2009

In the previous work we introduced a new static cylindrically symmetric vacuum solution in Weyl coordinates in the context of the metric f(R) theories of gravity.1 Now we obtain a two-parameter family of exact solutions which contains a cosmological constant and a new parameter as β. This solution corresponds to a constant Ricci scalar. We proved that in f(R) gravity the constant curvature solution in cylindrically symmetric cases is only one member of the most generalized Tian family in GR. We show that our constant curvature exact solution is applicable to the exterior of a string. The sensibility of stability under initial conditions is discussed.
FRICTION AND WEAR BEHAVIOR OF SELECTED DENTAL CERAMICS
Authors: PARK JONGEE , PEKKAN GUREL , OZTURK ABDULLAH
Published: November 2009

The purpose of this study was to determine the friction coefficients and wear rates of six commercially available dental ceramics including IPS Empress 2 (E2), Cergo Pressable Ceramic (CPC), Cercon Ceram (CCS) and Super porcelain EX-3 (SPE). Bovine enamel (BE) was also tested as a reference material for comparison purposes. Samples of the dental ceramics were prepared according to the instructions described by the manufacturers in disk-shape with nominal dimensions of 12 mm × 2 mm. The wear tests were performed by means of a pin-on-disk type tribometer. The friction coefficients and specific wear rates of the materials were determined at a load of 10 N and rotating speed of 0.25 cm/s without lubrication. Surface morphology of the wear tracks was examined using a scanning electron microscope. Statistical analyses were made using one-way ANOVA and Turkey's HSD (P < 0.05).
MG63 OSTEOBLAST-LIKE CELLS RESPONSE OF SiC COATING FOR CARBON/CARBON COMPOSITES
Authors: ZHANG LEI-LEI , LI HE-JUN , LI KE-ZHI , LU JIN-HUA , SHEN XUE-TAO , LAN FENG-TAO
Published: November 2009

A SiC coating for carbon/carbon ( C/C ) composites was produced by pack cementation to use as a bonding and buffer layer between C/C composites and bioactive ceramic for application in orthopaedic implants. The microstructure and MG63 osteoblast-like cell responses of the coating were investigated. The results confirmed that the SiC coating displayed a dense and uniform microstructure. MG63 cells attached and spread favorably on SiC coating, and cell proliferation was better on SiC coating than on uncoated C/C composites surface. The SiC coated C/C composites have the potential to be used in artificial implants.
EFFECT OF IONIC SIZES OF HALIDE ANIONS OF POTASSIUM SALTS ON SURFACE AND INTERFACIAL TENSIONS OF BENZENE AND WATER INTERFACES FOR MUTUAL MIXING
Authors: SINGH MAN , MATSUOKA HIDEKI
Published: November 2009

Surface tension (γ, mN/m) of potassium halide salts with water and interfacial tension (IFT) (±0.01 mN/m) of benzene interfaces with water are reported at 298.15 K temperature. The 0.1, 0.5 and 1.0 mol kg-1 potassium fluoride ( KF ), chloride ( KCl ), bromide ( KBr ) and potassium iodide ( KI ) solutions were studied. The KCl, KBr, KF and KI increased the surface tension by 5.2, 4.0, 3.1 and 3.0%, respectively, with salt–water interaction influence by anionic sizes. The surface tension of water from air–water to benzene–water interfaces is decreased by 51% due to the benzene–water mutual interaction with dipolar and π-conjugation. The KI, KF, KCl and KBr salts decrease the IFT by 63, 61, 61 and 56%, respectively, because of larger differences in sizes of the anions and the K + with individual salt. The KI developed stronger interactions with an induced potential of a large sized I - anion that held the water engaged and integrated the aqueous phase with higher interfacial tension. The dipolar and π-conjugation interaction model is proposed with biphasic systems.
PREPARATION OF BIOACTIVE FILM ON Ti6Al4V
Authors: WANG QIANG , ZHANG YANG , YANG KE , TAN LILI
Published: November 2009

Titanium oxide films were prepared using an anodic oxidation method in sulfuric acid solution on the surface of Ti6Al4V alloy at room temperature. The surface energy was obtained by the measurement of contact angles and the calculation with Owens–Wendt–Kaeble's equation. Ti6Al4V with anodic film after chemical treatment with NaOH aqueous solution showed excellent apatite-forming ability and produced a compact apatite layer covering all the surface of titanium after soaking in three times concentration (SBF × 3) for three days. A bioactive titania-CaP film was obtained on Ti6Al4V . Scanning electron microscopy, X-ray diffraction and Fourier Transform Infra-Red were used to analyze composition changes of the bioactive film. It is concluded that the acceleration of the apatite nucleation on the anodized Ti6Al4V with chemical treatment in a modified simulated body fluid was attributed to the novel surface characteristics and the formation of sodium titanate hydrogel layer during chemical pretreatment. The treatment of Ti6Al4V by anodic oxidation and subsequently in NaOH is a suitable method for providing the metal implant with bone-bonding ability.
X-RAY INVESTIGATION OF Ti-DOPED HYDROXYAPATITE COATING BY MECHANICAL ALLOYING
Authors: HANNORA A. , MAMAEVA A. , MANSUROV Z.
Published: November 2009

Ti -addition to hydroxyapatites [Ca10(PO4)6(OH)2–HA] with 5.0 wt.% Ti content, was successfully deposited on titanium substrate by mechanical alloying (MA) method. The X-ray Diffraction (XRD) data indicated that some changes take place in the HA lattice as well as in the Ti substrate. The coating thickness of the as-synthesized sample was about 91.1 μm. Ti incorporation into the apatite structure caused lattice shrinkage. The heat treated sample shows that dominant phase was HA up to 600°C. The Ti -doped HA steadily transformed to β- and α-tricalcium phosphate at 800°C. Scanning Electron Microscopy (SEM) observations revealed cracks above the temperature of 600°C. The presence of cracks could be due to the difference in coefficients of thermal expansion of Ti -doped HA and Ti -alloy substrate.
Temporal responses to intrinsically coupled calcium and zinc dyshomeostasis in cardiac myocytes and mitochondria during aldosteronism
Authors: Kamalov German , Ahokas Robert A. , Zhao Wenyuan , Shahbaz Atta U. , Bhattacharya Syamal K. , Sun Yao , Gerling Ivan C. , Weber Karl T.
Published: November 2009

Intracellular Ca2+overloading, coupled to induction of oxidative stress, is present at 4-wk aldosterone/salt treatment (ALDOST). This prooxidant reaction in cardiac myocytes and mitochondria accounts for necrotic cell death and subsequent myocardial scarring. It is intrinsically linked to increased intracellular zinc concentration ([Zn2+]i) serving as an antioxidant. Herein, we addressed the temporal responses in coupled Ca2+and Zn2+dyshomeostasis, reflecting the prooxidant-antioxidant equilibrium, by examining preclinical ( week 1) and pathological ( week 4) stages of ALDOST to determine whether endogenous antioxidant defenses would be ultimately overwhelmed to account for this delay in cardiac remodeling. We compared responses in cardiomyocyte free [Ca2+]iand [Zn2+]iand mitochondrial total [Ca2+]mand [Zn2+]m, together with biomarkers of oxidative stress and antioxidant defenses, during 1- and 4-wk ALDOST. At week 1 and compared with controls, we found: 1) elevations in [Ca2+]iand [Ca2+]mwere coupled with [Zn2+]iand [Zn2+]m; 2) increased mitochondrial H2O2production, cardiomyocyte xanthine oxidase activity, and cardiac and mitochondrial 8-isoprostane levels, counterbalanced by increased activity of antioxidant proteins, enzymes, and the nonenzymatic antioxidants that can be considered as cumulative antioxidant capacity; some of these enzymes and proteins (e.g., metallothionein-1, Cu/Zn-superoxide, glutathione synthase) are regulated by metal-responsive transcription factor-1; and 3) although these augmented antioxidant defenses were sustained at week 4, they fell short in combating the persistent intracellular Ca2+overloading and marked rise in cardiac tissue 8-isoprostane and mitochondrial transition pore opening. Thus a coupled Ca2+and Zn2+dyshomeostasis occurs early during ALDOST in cardiac myocytes and mitochondria that regulate redox equilibrium until week 4 when ongoing intracellular Ca2+overloading and prooxidants overwhelm antioxidant defenses.
The enzymatic degradation of hyaluronan is associated with disease progression in experimental pulmonary hypertension
Authors: Ormiston Mark L. , Slaughter Graham R. D. , Deng Yupu , Stewart Duncan J. , Courtman David W.
Published: November 2009

Hyaluronan (HA) degradation fragments have been linked to inflammation in a wide range of lung diseases. In idiopathic pulmonary arterial hypertension, HA accumulation has been associated with advanced disease. In this study, we investigated the potential role of HA degradation in the early stages of disease by examining HA distribution, molecular mass, synthesis, and enzymatic degradation at different stages of disease progression in a rat model of monocrotaline (MCT)-induced pulmonary hypertension (PH). At 28 days post-MCT, severe PH was associated with increased total lung HA ( P = 0.04). In contrast, a significant decrease in total lung HA was observed on day 10, before the onset of PH ( P = 0.02). Molecular mass analysis revealed a loss of high molecular mass (HMM) HA at 10 and 24 days post-MCT, followed by an increase in HMM HA at 28 days. Expression of HA synthase 2 ( HAS2) was elevated in MCT-challenged animals at 24 and 28 days, consistent with increased synthesis of HMM HA. Analysis by Morgan Elson assay and zymography demonstrated increased hyaluronidase-1 activity in the lungs of MCT-challenged rats, indicating that the observed increases in HAS2 expression and HA synthesis were counterbalanced, in part, by enhanced degradation. The present data demonstrate that, in the MCT model, early-stage PH is associated with enhanced hyaluronidase-1 activity, while both degradation and synthesis are increased at later stages. Thus an early increase in the generation of proinflammatory HA fragments may play a role in the onset and progression of pulmonary arterial hypertension.
Amphiregulin attenuates bleomycin-induced pneumopathy in mice
Authors: Fukumoto Jutaro , Harada Chika , Kawaguchi Tomonobu , Suetsugu Saiko , Maeyama Takashige , Inoshima Ichiro , Hamada Naoki , Kuwano Kazuyoshi , Nakanishi Yoichi
Published: November 2009

Amphiregulin, an EGF receptor (EGFR) ligand, is essential for epithelial development in various organs. A recent report suggested that amphiregulin acts as a protective factor in a liver injury model. Little is known about the roles of amphiregulin in lung injury and pulmonary fibrosis. The purpose of the present study was to investigate the role of amphiregulin in an experimental model of bleomycin-induced pneumopathy in mice. C57BL/6 mice were administered a bleomycin hydrochloride solution intratracheally. Recombinant human amphiregulin was injected intraperitoneally at 6, 8, 10, and 12 days after the bleomycin instillation. The grades of inflammation and fibrosis were assessed histologically and biochemically, and the numbers of apoptotic cells were counted after TdT-mediated dUTP nick end labeling (TUNEL) staining in the lung tissues. We also examined downstream survival signals of EGFR, namely phosphorylated Akt and phosphorylated Erk, in lung tissues by Western blotting analysis and immunohistochemistry. Expression of intrinsic amphiregulin was increased in murine lung tissues after bleomycin instillation. Administration of recombinant amphiregulin improved the survival rate and suppressed the degrees of inflammation and fibrosis and the number of TUNEL-positive cells in lung tissues. Amphiregulin treatment enhanced the activation of Akt and Erk in lung epithelial cells. Amphiregulin may play a protective role in bleomycin-induced pneumopathy in mice, probably through the activation of survival signals. Administration of amphiregulin may be a novel therapeutic strategy against lung injury and fibrosis.