bluuebunny/crossref_metadata_2025 huggingface dataset:
Addendum: Survie de Staphylococcus aureus au cours de la préparation et de la conservation de lait écrémé en poudre. Problèmes posés par le dénombrement des survivants
Authors: Chopin A. , Tesone Silvia , Vila J.-P. , LeGraet Y. , Mocquot G.
Published: April 2010

Skim milk powders were contaminated with seven strains of Staphylococcus aureus previously isolated from dairy products. These organisms were either added to the concentrated milk before spray-drying or directly to the milk powder. Survival under spray-drying conditions similar to those used in commercial operations was dependent on drying conditions and on the test strain; 1/5 to 1/250 000 of the original populations could be recovered. Survival during storage of milk powder at room temperature depended on the test strain, moisture content, and the method used to contaminate the powder. Our results suggest that powder stored at room temperature for more than 3 months may contain enterotoxin but no detectable surviving S. aureus.Of the different media tested, direct inoculation of Baird–Parker agar and PPSA supplemented with Tweens reliably detected maximal numbers of viable cells. Other selective counting methods gave variable results dependent on the test strain, the age of the powder, and the method by which the powders were contaminated.The nature of cellular damage depended on whether or not the organisms had been exposed to the spray-drying process. Enumeration of populations in spray-dried samples was "superior" when selective media were supplemented with egg yolk or Tweens. [Translated by the journal]
Protection of mammalian cells from diphtheria toxin by exogenous nucleotides
Authors: Middlebrook John L. , Dorland Rebecca B.
Published: April 2010

Exogenous nucleotides were found to protect mammalian cells from the lethal effects of diphtheria toxin. Protective potency of a given nucleotide was base specific and phosphate chain length dependent. Full expression of protective potency required an intact nucleotide, but the effect did not appear to be mediated by nucleotide-induced phosphorylation. Nucleotides antagonized the binding of diphtheria toxin to its cell surface receptor in a manner that correlated with the degree of protection. It was concluded that cellular protection from diphtheria toxin by nucleotides results from inhibition of toxin–receptor binding and that nucleotides therefore may serve as valuable research tools for future studies.
Isolation of a non-tumor-inducing mutant of the Ti plasmid of Agrobacterium tumefaciens strain B6
Authors: Rapp Barbara J. , Kemp John D. , White Frank
Published: April 2010

A nonpathogenic mutant of Agrobacterium tumefaciens strain B6 was isolated and its properties compared with the parental strain in an effort to localize the mutation. Both B6 and its mutant (B6-95) had similar colony color and morphology, were ketolactose positive, utilized octopine, and contained plasmid DNA. Kinetic analysis of DNA reannealing showed that total DNA homology and plasmid DNA homology between B6 and B6-95 was at least 90%. The length of both plasmids was found to be 58 μm. Plasmid DNA from both B6 and the mutant was digested with endonucleases and the fragments separated by agarose gel electrophoresis. In all cases the pattern for B6 was identical with that of B6-95. The Ti plasmid from B6 and the mutant was transferred to an avirulent, plasmidless strain of A. tumefaciens by in vitro conjugation and transformation. All of the B6 transconjugants and transformants were virulent, whereas all of the mutant transconjugants and transformants were avirulent. Electrophoretic patterns of endonuclease-digested plasmid DNA from transformants were identical to those of plasmid DNA from B6. Therefore, we conclude that the virulence mutation lies on the Ti plasmid.
Phenotypic reversion of nitrogenase in pleiotropic mutants of Rhizobium meliloti
Authors: Barabás Ilona , Sik Tibor
Published: April 2010

In two out of three pleiotropic mutants of Rhizobium meliloti, defective in nitrate reductase induced by amino acid utilization in vegetative bacteria and in symbiotic nitrogen fixation, nitrogenase activity could be restored completely by purines and partially by the amino acids L-glutamate, L-aspartate, L-glutamine, and L-asparagine. The compounds restoring effectiveness in nitrogen fixation did not restore nitrate reductase activity in vegetative bacteria. The restoration of effectiveness supports our earlier conclusion that the mutation is not in the structural gene for a suggested common subunit of nitrogenase and nitrate reductase.
Régulation de la synthèse de la catalase chez Proteus mirabilis
Authors: Jouve H. , Sauret G. , Labouré A. M. , Pelmont J.
Published: April 2010

During the log-phase growth of Proteus mirabilis the specific activity of catalase decreases, while at the beginning of or during the stationary phase an increase takes place which is abolished by inhibitors of nucleic acid or protein synthesis. Glucose in the culture medium has no appreciable effect on the level of enzyme synthesis nor does the passage of bacteria to anaerobiosis bring any noticeable change. Successive additions of hydrogen peroxide up to weak final concentrations (0.2–0.5 mM) stimulate catalase synthesis. Determination of the enzyme in vivo reveals but a weak proportion of the total catalase which can only be titrated after the breakdown of cells. The titrable enzyme in vivo represents, as an order of magnitude, the activity found associated with the cell wall, in an easily released form after the mechanical separation of the inner and outer membranes. Thus, bacteria can act upon exogenous peroxide only through a peripheral catalase while they possess in a masked form an important reserve of cytoplasmic enzyme.
Propriétés d'un mutant de Proteus mirabilis résistant au peroxyde d'hydrogène
Authors: Sauret G. , Jouve H. , Pelmont J.
Published: April 2010

A peroxide-resistant mutant (PR) was isolated from Proteus mirabilis using the hydrogen peroxide mutagenic property. Under the same conditions, resistance of mutant PR bacteria to H2O2 was 50 to 100 times greater than that of the wild type. The total amount of catalase produced by P. mirabilis PR was on the average 10 times greater than that of the wild type. When PR bacteria were subjected to high doses of H2O2 (150 mM), the determination of catalasic activity in vivo increased; paradoxically, there was a net decrease in the activity of the solubilized catalase after the breakdown of the cells. The hypothesis of an enzyme transfer from the inside towards the periphery of the cells is discussed. The behavior of a membrane enzyme (L-phenylalanine oxidase) of the PR mutant shows that H2O2 may cause lesions way up to the internal membrane of bacteria.
Production of an extracellular ribonuclease by Pseudomonas maltophilia
Authors: Arella M. , Sylvestre M.
Published: April 2010

As part of a screening program for pseudomonad enzymes having an industrial interest, we selected ribonuclease (RNase) producing strains. Of the 150 pseudomonads screened, 6 were found to produce an extracellular RNase activity when grown on solid medium. In broth culture, the RNase activity from these six species remained bound to the cells unless gelatin was added to the medium. Gelatin was essential for the release of RNase in the broth culture, but the pH of the medium, addition of potential inducers such as nucleic acids, or addition of cations did not affect this release. However, gelatin did not appear to induce the synthesis of the enzyme. Strain B-88, identified as Pseudomonas maltophilia, was selected for further study of the enzyme. The extracellular RNase isolated from B-88 broth cultures could be separated in two fractions on the basis of the molecular weight by the ultrafiltration technique. The low molecular weight fraction reacts optimally at temperatures between 55 and 60 °C and optimal pH values varying from 7.4 to 9.5. At neutral or alkaline pH, the enzyme was stable at temperatures below 37 °C but was inactivated at 55 °C. The RNase was inhibited by mercury and cobalt and stimulated by magnesium.
Plasmid-determined 2-hydroxypyridine utilization by Arthrobacter crystallopoietes
Authors: Weinberger M. , Kolenbrander P. E.
Published: April 2010

Arthrobacter crystallopoietes has the ability to utilize 2-hydroxypyridine (2-HP) as a source of carbon and nitrogen and forms a blue extracellular pigment when grown in the presence of 2-HP. Ultracentrifugal analyses of pigment producing(Pig+) and pigment nonproducing(Pig−) strains of A. crystallopoietes revealed the presence of plasmid material in both strains. Recovery of plasmid DNA from Pig+ strains is two or three times greater than from Pig− strains. The molecular weight of plasmid DNA recovered from Pig+ strains (63 Mdaltons) is slightly higher than the molecular weight of plasmid DNA from Pig− strains. Consistent with the characterization of plasmid DNA from the two strains is that Pig+ strains contain a 63-Mdalton plasmid encoding 2-HP utilization as well as a cryptic plasmid of very nearly equal molecular weight. Pig− strains contain only the cryptic plasmid.
Nitrogen fixation by Rhizobium sp. 32H1. A morphological and ultrastructural comparison of asymbiotic and symbiotic nitrogen-fixing forms
Authors: Brussel A. A. N. Van , Costerton J. W. , Child J.J.
Published: April 2010

The induction of nitrogenase (C2H2) activity in asymbiotically cultured Rhizobium sp. 32H1 was found to be associated with morphological changes in the cells which were more pronounced than those seen in bacteroids. Polyphosphate granules were found in both bacteroids and cultured cells, but poly-β-hydroxybutyrate vesicles were almost absent in bacteroids but were present in cultured cells. Freeze-etching techniques revealed no differences between the asymbiotically cultured nitrogen-fixing forms and bacteroids in that both the cell wall and cytoplasmic membrane cleavage planes were normal for gram-negative bacteria.
Polyadenylate-containing RNA in dormant and germinating Botryodiplodia theobromae pycnidiospores
Authors: Etten James L. Van , Rawn Carroll D.
Published: April 2010

Hybridization of [3H]polyuridylic acid to RNA isolated from Botryodiplodia theobromae pycnidiospores yielded an estimate of about 6.25 × 105 polyadenylate-containing RNA (poly A(+) RNA) molecules per dormant spore. The number increased about fourfold by the time of germ tube emergence at 3 h. The average size of this presumed mRNA was about 4.1 × 105 daltons (1275 nucleotides), with an average polyadenylate segment length of 26 nucleotides. Neither of these values changed significantly during germination. The earliest detectable (first 30 min of germination) de novo synthesized mRNA's were rapidly incorporated into polyribosomes. This newly synthesized, presumably functional, mRNA was composed of both poly A(+) RNA and polyadenylate-lacking RNA. The average sizesof the two polyribosomal mRNA subpopulations and the total poly A(+) RNA population were identical.
Isolation and characterisation of guanine auxotrophs in Saccharomyces cerevisiae
Authors: Gardner W. J. E. , Woods R. A.
Published: April 2010

Mutants of yeast which are auxotrophic for guanine have been isolated from two prototrophic haploid strains, one of which carried the suppressor of purine excretion, su-pur, and the other carried the alternative allele, su-pur+. The mutants were allocated to three genes, gua1, gua2, and gua3, between which no close linkage was demonstrable. Mutants of all three genes were recessive and showed normal Mendelian segregation in crosses. The gene gua1 was shown by an in vivo enzyme assay procedure to specify guanosine 5′-phosphate (GMP) synthetase, the second enzyme involved in the biosynthesis of GMP from inosine 5′-phosphate (IMP). Mutants of this gene excrete large amounts of purine derivatives, predominantly xanthosine, into guanine-free, but not into guanine-supplemented, medium. The gene gua2 is probably involved in the biosynthesis of riboflavin from guanine nucleotides; the phenotype of these mutants suggests a possible interaction between aromatic amino acid metabolism and riboflavin biosynthesis. No role for gua3 can be assigned on the evidence so far available, but it is not involved in the specification of IMP dehydrogenase, the first enzyme involved in the synthesis of GMP and IMP.
In vitro attachment of Treponema hyodysenteriae to mammalian epithelial cells
Authors: Knoop Floyd C. , Schrank Gordon D. , Ferraro Frank M.
Published: April 2010

The interaction between Treponema hyodysenteriae and isolated swine intestinal epithelial cells or mouse adrenal cells in culture was examined. Studies were performed in which treponemes were incubated with each type of animal cell in an atmosphere of 5% CO2 in air. Coincubation was terminated at various time intervals, and the percentage of treponemal attachment evaluated by light microscopy. The extent of attachment was dependent on both incubation time and temperature. The mechanism of attachment to the animal cell surface was examined by scanning electron microscopy. Interaction of the parasite with the host cell did not appear to alter cellular morphology or result in changes of the cell surface at the site of attachment. Preference for a cellular site of attachment was not found.
Isolation and characterization of isogenic E. coli strains with alterations in the level of one or more major outer membrane proteins
Authors: Foulds John , Chai Tuu-Jyi
Published: April 2010

Nearly isogenic Escherichia coli strains which carry mutations leading to altered levels of major outer membrane proteins have been prepared and genetically characterized.
Increase in the in vitro susceptibility of Staphylococcus aureus to antimicrobial agents in the presence of Candida albicans
Authors: deRepentigny J. , Lévesque R. , Mathieu L. G.
Published: April 2010

In experiments with mixed cultures of Staphylococcus aureus and Candida albicans both in the absence and in the presence of 5-fluorocytosine (5-FC), we have observed that (1) there is an inhibition of S. aureus growth in mixed cultures with C. albicans in media supplemented with 1 μg/mL of 5-FC and that 5-FC has no effect on staphylococci in pure cultures; (2) this inhibition occurred with clinically isolated and laboratory strains and could be reversed by specific metabolites; (3) Staphylococcus aureus was inhibited by filtrates of C. albicans cultures treated with 5-FC and this seemed to be favored by some C. albicans filterable product which can affect the cell wall and the permeability of the staphylococcal cells since they become sensitive to 5-FC; (4) nine other commonly used antimicrobials showed an increased inhibitory activity against S. aureus in mixed cultures with C. albicans; and (5) there is a decrease in the number of precipitating antigens of S. aureus and of the activity of alpha toxin when this species was grown with both C. albicans and 5-FC. Our results indicate that the susceptibility of some species to antimicrobials could be significantly modified in the presence of other species. One cannot exclude that a similar phenomenon could happen in hosts under treatment with antibiotics against infection.
Structural and biochemical examination of ghosts derived from a deep rough (heptose-deficient lipopolysaccharide) strain and a smooth strain of Escherichia coli
Authors: Irvin R. T. , Lam J. , Costerton J. W.
Published: April 2010

Outer membrane derived 'ghosts' can be readily generated from both smooth and deep rough (heptose-deficient LPS) strains of Escherichia coli 08. Morphological and biochemical studies confirmed that 'ghosts' of both strains are composed of protein (four major proteins), LPS, and phospholipid (cardiolipin and phosphatidylethanolamine) in the form of a single membrane of roughly the same shape as intact normal cells. The ghost membrane cleaves only slightly in freeze-etch preparations of ghosts derived from the smooth strain as compared to the extensive cleavage plane of ghosts derived from the rough strain. The asymmetrical distribution of ghost proteins was visualized, by critical point drying and shadowing with platinum, as a relatively smooth outer surface with some discernible particles (10–15 nm) and an extremely particulate inner surface (10–15-nm particles). Ghosts derived from the smooth strain retained their structure following chloroform–methanol extraction, while ghosts derived from the rough strain fragmented with chloroform–methanol extraction. Evidence is presented that LPS–protein interactions as well as protein–protein interactions are significant in maintaining the ghost structure.
Ecology and taxonomy of bacteria attaching to wood surfaces in a tropical harbor
Authors: Austin B. , Allen D. A. , Zachary A. , Belas M. R. , Colwell R. R.
Published: April 2010

Water, sediment, and wooden pilings, samples of which were collected from a harbor in Puerto Rico during the course of a long-term study of biofouling of wood treated with creosote and related compounds, were found to support growth of microbial populations, the dominant taxa of which included Hyphomicrobium, Hyphomonas, Pseudomonas, Vibrio, and Bacillus. New wood exposed to the harbor water was rapidly colonized by Hyphomicrobium vulgare. Old pilings in an advanced stage of biodeterioration maintained a diverse bacterial microflora, representatives of which were also found widely distributed in the water column and sediment. Evidence for bacterial species succession was obtained, indicating that microbial interactions are important for attachment to, and subsequent colonization of, wood surfaces in the marine environment.
Etude expérimentale du transfert de Vibrio parahaemolyticus (biotype 2) de l'eau et des sédiments aux organismes des chaînes alimentaires benthiques marines
Authors: Gauthier M. J. , Clement R.
Published: April 2010

Transfer of Vibrio parahaemolyticus (biotype 2) from sediments to water and from water to benthic marine organisms was studied experimentally using a streptomycin-resistant strain. Transmission by trophic pathways was also studied using reconstituted marine food chains (Mytilus edulis, Nereis diversicolor, Carcinus maenas, Scorpaena porcus, Mus musculus).Water colonization by sediments could be observed only at temperatures above 16 °C. Sediments could well constitute a disseminating reservoir for these germs, their cycle in water being dependent of the cycle followed in the sediments.Contamination of animal organisms is essentially effected by a direct mean, either water or sediments; transfer by trophic pathways being negligible. Infection of land consumers (mice) is linked quantitatively to the nature of the last marine organism of the food chain since bacteria can flourish in the digestive tract of certain animals (Carcinus maenas).
Trypsin-uncoupled synthesis and secretion of yeast invertase: implications for the mechanism of secretion
Authors: Holbein Bruce E. , Kidby Denis K.
Published: April 2010

The subcellular distribution of invertase was examined after synthesis and secretion by sphaeroplasts had been uncoupled by the addition of 30 μg mL−1 trypsin. Sphaeroplasts secreted only the high molecular weight invertase during uncoupling by trypsin. The level of low molecular weight, 'small' invertase in the soluble internal pool was found to be elevated by over fivefold, and the membrane-associated pool was found to contain low molecular weight invertase in addition to intermediate molecular weight invertase, after 1.5 h of trypsin treatment. Purified plasma membranes from trypsin-treated sphaeroplasts had no detectable mannan synthetase activity. On the basis of these and previous findings, a working hypothesis wherein invertase is synthesized on the internal surface of the plasma membrane and glycosylated during its transit to the external surface is presented.
Aquarium pets as a source of antibiotic-resistant salmonellae
Authors: Trust T. J. , Bartlett Karen H.
Published: April 2010

Thirteen serotypes of Salmonella isolated from imported ornamental aquarium frogs, snails, and their waters were shown to be multi-drug-resistant. Among the resistances exhibited were resistance to gentamicin, sulfamethoxazole–trimethoprim, cephalothin, and nalidixic acid. Frog isolates displayed eight different patterns and snail isolates had two different resistance patterns. The most common serotype, Salmonella typhimurium, was resistant to 18 antibacterials while other salmonellae were resistant to 9 to 16 antibacterials. Resistances in S. typhimurium and S. bovis-morbificans were conjugative and a number of R plasmids participated in the resistance. The plasmid-mediated resistance in S. typhimurium was stable and the levels of resistance conferred were markedly higher than in the other salmonellae tested. Resistance of other serotypes was non-conjugative and resistance to the β-lactam antibiotics was unstable.
Effects of some platinum IV complexes on cell division of Escherichia coli
Authors: Ferguson C. A. , Murray R. G. E. , Lancy Jr. P.
Published: April 2010

A comparison was made of the effects of cis-tetrachlorodiaminoplatinum (IV) (cis-TCDPt), rans-TCDPt), and hexachloroplatinum (HCP) on growth and cell division of Escherichia coli strains D21 and D22. At or below 40 μg/mL, cis-TCDPt inhibited cell division but not growth, DNA, or protein synthesis, although areas of increased electron density could be demonstrated in treated cells. In contrast, 40 μg/mL of trans-TCDPt or HCP inhibited growth. Trans-TCDPt-treated cells developed condensed nucleoids; HCP-treated cells showed no obvious cytological changes to correlate with growth inhibition. Combination of cis-TCDPt with nalidixic acid, both at one-half the lowest filament-forming concentrations, resulted in formation of filaments, suggesting an additive effect. Combination of cis-TCDPt followed by ampicillin on E. coli B/r resulted in single bulges near the center of the filaments. Cis-TCDPt could therefore inhibit an initial step in the septation sequence, possibly at the level of the regulation of the hydrolytic enzymes. Whether cis-TCDPt exerts its effect by interreaction with DNA or with a membrane target is still uncertain.
Phosphate uptake in chemostat cultures of Escherichia coli K-12 subjected to periodic β-glycerophosphate pulsing: a system for assaying alkaline phosphatase
Authors: Francis J. C. , King S. L.
Published: April 2010

Limiting concentrations of β-glycerophosphate were pulsed into chemostat cultures of Escherichia coli K-12 at intervals equal to the population doubling time. The resultant culture density fluctuations are interpreted in terms of inorganic phosphate uptake which, in this system, is a function of alkaline phosphatase activity. Information concerning in vivo alkaline phosphatase activity at suboptimal (acidic) pH with very low concentrations of substrate (β-glycerophosphate) is obtained from kinetic analysis of uptake data.
Structure of nitrogen-fixing nodules formed by Rhizobium on roots of Parasponia andersonii Planch.
Authors: Trinick M. J.
Published: April 2010

The structure of nitrogen-fixing nodules produced by Rhizobium infection of the non-legume Parasponia andersonii was examined by light and electron (both SEM and TEM) microscopy. Comparisons were made with the nodules previously described on P. rugosa. Like the nodules on different non-legumes formed by other types of endophytes, the Rhizobium nodules on Parasponia resembled modified roots by having a central vascular bundle surrounded by an endophyte-infected zone. The intimate association between the Rhizobium and the host nodule cell was compared with the Rhizobium association found in legumes. The rhizobia were not released from the infection thread as happens in the legume. The infection thread, which propagates the Rhizobium infection to new cells, was transformed within a nodule cell from a darkly stained (light microscopy) or very electron-dense (TEM) structure to a number of thread types. The walls of the threads varied greatly in thickness and often the thread structures were without rigid walls and were only enclosed by a plasma membrane. If the rhizobia are transformed into bacteroids, as in the legumes, it would have to occur when the threads had reached their mature size, when bacterial division had ceased. Nitrogen fixation was considered to occur in all thread types.
Deoxyribonucleic acid relationships among members of the genus Aeromonas
Authors: MacInnes Jan I. , Trust Trevor J. , Crosa Jorge H.
Published: April 2010

Polynucleotide sequences among 24 motile and 11 non-motile aeromonads were studied by analysis of deoxyribonucleic acid – deoxyribonucleic acid (DNA–DNA) duplexes with endonuclease S1. In addition, DNA base composition (mole % guanine and cytosine (G + C) and relative genome sizes were determined for selected strains. Large variations in genome size were found and % GC ranged from 57.1 to 62.9%. On the basis of the strains examined, the Genus Aeromonas consists of two genotypically legitimate groups: a diverse group of motile aeromonads, and the genetically more homogeneous non-motile aeromonads, comprising the species Aeromonas salmonicida. Internal homology groups could not be demonstrated within the motile aeromonads, and significant divergence in related sequences was indicated. This diverse motile group forms the single species Aeromonas hydrophila.
Experimental studies of the pathogenesis of infections due to Pseudomonas aeruginosa: extracellular protease and elastase as in vivo virulence factors
Authors: Holder Ian Alan , Haidaris Constantine G.
Published: April 2010

The effects on mortality of supplemental injections of protease and elastase were determined in burned mice infected with non-lethal inocula of a toxin-producing but non-proteolytic- enzyme-producing strain of Pseudomonas aeruginosa. When a variety of solutions containing proteolytic enzyme were injected under these conditions, the mortality increased significantly. This did not occur when organisms other than P. aeruginosa were used. Injections of the enzyme solutions alone were non-lethal. Injection of a solution of α2-macroglobulin, which was shown to inhibit proteolytic activity, together with a proteolytic enzyme – toxin producing strain of P. aeruginosa caused a significant delay in mortality when compared with controls. It was concluded that protease, elastase, and toxin production were necessary for P. aeruginosa to express full virulence in the burned mouse model.
Mannose transport in Amphora coffeaeformis var. perpusilla (Bacillariophyceae)
Authors: Chansang Hansa , Cooksey Keith E.
Published: April 2010

Amphora coffeaeformis var. perpusilla is able to concentrate but not metabolize mannose. The sugar, which can be accumulated against a concentration gradient, is taken up only after a short lag. Preincubation with glucose allows immediate mannose uptake. Substances that reduce the ATP content of the diatom cells also inhibit mannose uptake, as do sugars of similar stereochemical configuration. Mannose appears to act as a non-metabolizable analogue of glucose in these respects.
Induction et repression de la synthèse de collagénase chez Acinetobacter sp.
Authors: Monboisse Jean-Claude , Labadie Jean , Gouet Philippe
Published: April 2010

The synthesis of collagenase in Acinetobacter sp. was found to be inducible by denatured collagen and by its high molecular weight fragments. The presence in the inducer of part of the tertiary structure appear to be indispensable. On the other hand, an addition of Casamino acids, meat protein hydrolysate, or a mixture of amino acids with a similar composition to gelatin does not stimulate collagenase synthesis.Enzyme production was severely repressed in the early phase of growth by glucose, arabinose, and ribose, single amino acids, proline, hydroxyproline, alanine, glutamic acid, or casein acid hydrolysate. A mechanism of repression similar to catabolite repression was involved in the phenomenon caused by carbohydrates. However, the fact that cyclic adenosine 3′5′-mono-phosphate did not overcome the repression caused by amino acids or Casamino acids, in contrast to classical catabolite repression, suggests that these two forms of repression may be distinct. [Traduit par le journal]
Physiological studies of a temperature-sensitive sporulation mutant of Bacillus cereus T
Authors: Stelma Jr. G. N. , Sadoff H. L.
Published: April 2010

Growth of temperature-sensitive mutant Bacillus cereus T JS22-C occurred normally at the restrictive temperature (37 °C), but sporulation was blocked at stage 0. The production of extracellular and intracellular proteases and of alkaline phosphatase occurred at 37 °C, but the expression of a functional tricarboxylic acid cycle did not. At the permissive temperature (26 °C), the mutant sporulated at a slightly lower frequency (60%) and at a lower rate than the parent strain. The oxidation of organic acids, which accumulate in the growth medium began at T0 in cultures of the parent strain but was delayed until about T3 in cultures of the mutant. Later events in sporulation were also delayed in the mutant by about 3 h. Experiments in which the temperature of growth was shifted from 37 to 26 °C or from 26 to 37 °C at various times showed that the temperature-sensitive event began approximately 1 h after the end of exponential growth and ended when the cells reached the end of stage II (septum formation). The absence of a functional tricarboxylic acid cycle in cells of the mutant grown at 37 °C or shifted from 26 to 37 °C before T1 did not appear to be due to a lesion in one of the structural genes of the tricarboxylic acid cycle but was more likely due to the inability of the cells to derepress the synthesis of some of the enzymes of that cycle.
Influence de la longueur de la chaine saccharidique des lipopolysaccharides bactériens sur la stimulation du système immunitaire
Authors: Lallier R. , Nigam V. N. , Brailovsky C. A.
Published: April 2010

Three lipopolysaccharides (LPS) of different chain length were used as adjuvant. The one of shortest chain length is the most effective in enhancing antibody titer in rats against sheep red blood cells, suggesting that lipid A and KDO were responsible for the stimulatory effect of LPS.
High yields of coatless spores of Clostridium perfringens strain 8–6 in a defined medium
Authors: Sacks L. E. , Thomas R. S.
Published: April 2010

Coatless spores of mutant strain 8–6 of Clostridium perfringens were formed reproducibly at levels exceeding 107/mL in a defined medium. Confirming previous observations, the spores are quite stable in water and resistant to heat, octanol, and ethanol. They also resist 5% phenol. Electron microscopy confirms, with further evidence, the probable absence of any structure exterior to the cortex. The levels of sporulation attained are sufficient to permit recovery and purification for future studies on physicochemical and germination properties. The defined medium makes possible studies on spore coat (and exterotoxin) biosynthesis and coat assembly.
Thymidine incorporation into Rhizobium meliloti
Authors: Behki R. M. , Lesley S. M.
Published: April 2010

Thymidine is rapidly catabolized to thymine, β-aminoisobutyric acid, and carbon dioxide by Rhizobium meliloti cells. The incorporation of labelled thymidine into the DNA of R. meliloti cells can be enhanced by the addition of low concentrations (10–20β μg/mL) of deoxyadenosine or other nucleosides (adenosine, uridine, guanosine). However, at high concentrations (>50 μg/mL) these compounds inhibit thymidine incorporation. Conditions to obtain highly radioactive DNA of Rhizobium are described.
A new plaque system for canine distemper: characteristics of the green strain of canine distemper virus
Authors: Ho C. K. , Babiuk L. A.
Published: April 2010

A Vero cell adapted Green strain of canine distemper virus (CDV) was tested for its plaque-forming capacity in different cell lines. Plaque formation was observed in HEp-2, BS-C-I, and HeLa cells but not in Vero or dog kidney cells even though replication and cytopathology were observed in the latter cell types. In the cells in which the virus was capable of producing plaques, the plaques were observed within 24 h post infection and continued to increase in size with subsequent cellular destruction such that by 72 h postinfection the size of the plaques approached 0.5 mm. With the use of the plaquing technique, it was possible to demonstrate the thermal lability of the virus as well as the kinetics of adsorption. Thus, it was shown that the half-life of the virus was 125 min at 25 °C, 75 min at 35 °C, and 65 min at 37 °C. The rate of adsorption of CDV to HEp-2 cells was 17.2% in 30 min at 37 °C and continued slowly for 4 h before completion. Application of this rapid plaque-forming assay to plaque-reduction tests for CDV antibody and for CDV-infected cells by the infectious center assay are described.
Immunological properties of partially purified material with monocytosis-producing activity from Listeria monocytogenes
Authors: Otokunefor T. V. , Shum D. T. , Galsworthy S. B.
Published: April 2010

A fraction rich in a monocytosis-producing activity (MPA) has been obtained by a two-stage chromatographic separation from a saline extract (SE) of Listeria monocytogenes. Like SE, the purified material elicits monocytosis and decreases the halftime of circulating monocytes. The purification of MPA eliminates the following found in SE: the in vitro mitogenic activity, the in vitro adjuvant activity, the immunosuppressive activity, and the granulocytosis-promoting and the lymphopenia-inducing activities.
Etude d'un groupe nouveau d'Enterobacteriaceae (groupe H1) apparenté à l'espèce Enterobacter cloacae
Authors: Izard D. , Gavini F. , Trinel P. A. , Leclerc H.
Published: April 2010

A DNA–DNA hybridization study was carried out on a new group of enterobacteria (group H1) previously studied by numerical taxonomy work on the genus Enterobacter. This group showed a very high genetic homogeneity since the average relative binding ratio of nine analysed strains is equal to 91%. The taxonomic position of this group into the family of enterobacteria is discussed with the species E. cloacae (37 to 61%), K. pneumoniae (44 to 60%), K. oxytoca (57–58%), L. malonatica (syn. Citrobacter intermedius, a: 46 to 54%), L. amalonatica (syn. C. intermedius, b: 51%), and the group H3 (52–61%). The group H1 is defined on phenotypic and genetic data.
Minute tubular forms in soil
Authors: Casida Jr. L. E. , Liu Kang-Chien
Published: April 2010

Large numbers of minute, flat, long, straight, but often broken structures were observed in aqueous extracts of soil. We have applied the purely descriptive term 'tubules' to these structures, because they apparently became flattened during preparation for electron-microscopic viewing. The tubules appared to be composed of parallel fibers held together by protein. Most of the tubules fell within a range of 10 to 50 nm in width. Lengths (of broken pieces) ranged from 0.2 to 1 μm or more. A few unbroken ends were found. They were rounded. Tubular structures of similar dimensions were found surrounding lysed cells in sectioned preparations of bacteria that had been separated from soil. The tubules were present in surface soils but not a subsurface sample. Their numbers decreased during bacterial multiplication in soil or broth containing soil. No evidence was found of cleared areas or increase in number of tubules when the tubules were plated with a heterogeneous microbial flora from soil.
Influence of soybean inoculation and nitrogen levels on populations and serogroups of Rhizobium japonicum in Ontario
Authors: Semu Ernest , Hume D. J. , Corke C. T.
Published: April 2010

Strains and numbers of Rhizobium japonicum in the soil can influence soybean (Glycine max (L.) Merrill) yields but R. japonicum serogroups and numbers in Ontario soils have not been studied. In 1976 and 1977, the influences of inoculation and fertilizer nitrogen (N) levels on populations, measured by most probable number (MPN) techniques, and serogroups of R. japonicum were studied at three Ontario sites. The locations, near Ridgetown, Elora, and Woodstock, represented areas where soybeans had been grown many times previously, only a few times or not at all, respectively. Treatments were (a) un inoculated + O N; (b–e) inoculated +0, 50, 100 or 200 kg N/ha.At Ridgetown, MPN's, expressed on log10 bases, ranged from 5.17/g soil in 1977 to 7.02 in 1976. At Elora, comparable values were from 3.66 to 6.43. Inoculation did not increase MPN's at either site. At Woodstock, inoculation increased MPN's from 0 to about 2.47 in both years. Nitrogen application did not change the MPN values at any site in either year.Serogroup 110 predominated in the nodules at Ridgetown in both years. At Elora, serogroup 123 was found most frequently in nodules. Serogroups 311b 138 in 1976 and 122 and 125 in 1977 were found most frequently after inoculation at Woodstock. Additions of fertilizer N had only slight effects on the distribution of serogroups in the nodules.
Effect of oxygen on batch and continuous cultures of a nitrogen-fixing Arthrobacter sp.
Authors: Cacciari Isabella , Lippi Daniela , Bordeleau Lucien M.
Published: April 2010

Growth, acetylene reduction, and respiration rate were studied in batch and continuous cultures of Arthrobacter fluorescens at different oxygen partial pressures. The optimum pO2 values for growth and acetylene reduction were 0.05 and 0.025 atm, respectively, but microorganisms can tolerate higher pO2 values. The growth of cultures provided with combined nitrogen was dependent on oxygen availability, and strict anaerobic conditions did not support growth. Acetylene reduction of a population grown in continuous culture and adapted to low pO2 (0.02 atm) was much more sensitive to oxygenation than that of a population adapted to high pO2 (0.4 atm). Their maximum nitrogenase activity, at their optimal pO2 values, were quite different. The respiratory activity of nitrogen-fixing cultures increased with increasing oxygen tensions until a pO2 of 0.2 atm. At higher pO2 values, the respiration rate began to decrease.
Utilization of sea water–urea as a culture medium for Spirulina maxima
Authors: Faucher Onil , Coupal Bernard , Leduy Anh
Published: April 2010

The possibilities of utilization of seawater enriched with urea as the culture medium for a blue-green alga, Spirulina maxima, were investigated. Pretreatment by precipitation with NaHCO3 and (or) Na2CO3 was found essential to remove the excess amounts of Ca2+ and Mg2+ present in seawater prior to cultivation. A culture medium as good as the synthetic medium reported in the literature for the growth of S. maxima was obtained after treating seawater with NaHCO3 (19.2 g/L) at pH 9.2 and 35 °C for 2 h, filtering to remove precipitates, and enriching with K2HPO4 (0.5 g/L), NaNO3 (3.0 g/L), and FeSO4 (0.01 g/L). The same results were obtained by substituting a small amount (0.2 g/L or less) of either crystalline or polymerized urea for the NaNO3 in the above medium. Growth of S. maxima was inhibited at higher concentration s of urea in the culture medium. The inhibition effect was due to the partial decomposition of urea into ammonia in alkali medium. Tests conducted on the 130-L cultivation open pond also confirmed that the seawater–urea medium supports growth of S. maxima as well as the best known synthetic medium.
Age-related physiological studies comparing Candida albicans chlamydospores to yeasts
Authors: Miller Sara E. , Finnerty W. R.
Published: April 2010

From electron-microscopical observations, a decreased metabolic activity in 3-day-old Candida albicans chlamydospores was suggested, and progressive deterioration in chlamydospores aged 2–8 months was shown. Oxygen utilization by chlamydospore–pseudomycelium (CSP) preparations was less than that by yeast, while 3-day-old CSP preparations used significantly less O2 than 24-h CSP preparations. Amino acid incorporation was greater in yeast than in CSP preparations. Leucine incorporation by 20-h yeasts was twice that of 5-day yeasts and 5 times that of 20-h and 5-day CSP. Amino acid decarboxylation was similar in yeasts and CSP and was determined by end-product analyses to be via amino acid oxidase. Light microscopy autoradiography of [14C]leucine incorporation demonstrated that the metabolic activity in CSP preparations was due to the young growing tips of the pseudomycelium and not to mature chlamydospores. Yeasts did not take up trypan blue but could be stained if first autoclaved or treated with 10% acid or 10% base. Young chlamydospores grown in the presence of trypan blue developed unstained and became permeable to the dye at [Formula: see text] days. These data suggest that chlamydospores of C. albicans do not function in the classical role attributed to spores; i.e., mature chlamydospores cannot germinate, but rather age, deteriorate, and die.
Investigation of antibodies against Fasciola hepatica in moose Alces americana
Authors: Brindle Yves , Letarte Robert , Gagnon Jocelyne
Published: April 2010

A serological investigation was carried out to check the presence of antibodies against Fasciola hepatica in a collection of 125 sera of moose Alces americana killed in the Province of Quebec. As revealed by hemagglutination tests, two moose had titers suggesting contact with this parasite.
Fingerprinting bacterial chromosomal DNA with restriction endonuclease EcoRI: comparison of Rhizobium spp. and identification of mutants
Authors: Mielenz Jonathan R. , Jackson L. E. , O'Gara F. , Shanmugam K. T.
Published: April 2010

Total cellular DNA from Rhizobium trifolii, R. meliloti, and R. japonicum strains 110 and 117 were prepared. DNA fragments generated with restriction endonuclease EcoRI from these DNA samples were compared in agarose gels after electrophoresis. DNA cleavage patterns generated from R. japonicum strain 110, R. trifolii, and R. meliloti were clearly distinguishable from each other. Restriction endonuclease cleavage patterns of DNA from R. japonicum strain 110 and presumptive R. trifolii mutant strains that nodulate soybean were found to be similar. Rhizobium trifolii mutant strains were also lysed by a phage specific for R. japonicum strain 110. These results show that "R. trifolii mutant strains" are indeed derivatives of R. japonicum strain 110 and not R. trifolii.
Relationship between carbon source and susceptibility of Cephalosporium acremonium to selected amino acid analogues
Authors: Mehta R. J. , Nash C. H.
Published: April 2010

The susceptibility of Cephalosporium acremonium to selected amino acid analogues was markedly influenced by the carbon source used in the test media. Lysine hydroxamate, β-hydroxy norvaline, and hexafluorovaline were toxic when tested with ribose, ribose or fructose, and ribose or galactose, respectively. In contrast, thialysine and thiaisoleucine inhibited C. acremonium with glucose, fructose, galactose, sucrose, mannitol, sorbitol, and soluble starch. Neither of these analogues was toxic at levels tested when glycerol was used as a carbon source. The minimal inhibitory concentrations (MIC) of thialysine, homoserine, and α-methylserine were > 1000, > 1000, and 250 μg/mL, respectively, with glycerol. In contrast, the MIC values for the same three analogues were 31, 62, and 125 μg/mL, respectively, with mannitol. The matching of the carbon sources with the specific amino acid analogues expands the number of analogues useful for selecting derepressed mutants. Thialysine-resistant mutants (tlysR) of C. acremonium which excrete lysine were isolated on a medium containing mannitol.
Bacterial utilization of a hydrazine derivative as nitrogen source for growth
Authors: LaRue T. A. , Child J. J.
Published: April 2010

The ability of microbes to metabolize the N–N bond seems rare. Pseudomonas sp. from soil can utilize 1,4,5,6-tetrahydro-6-oxo-3-pyridazinecarboxylic acid as C and N source. This appears to be the first report that a microbe can cleave a nitrogen–nitrogen bond in an organic compound and use the products for growth.
The ultrastructure of the major species of an enriched methanogenic culture utilizing acetic acid
Authors: Colvin J. Ross , Sowden L. C. , Berg L. van den
Published: April 2010

The ultrastructure of the cells of the major component of an enriched culture of a presumed methanogen which utilized acetic acid was studied by transmission and scanning election microscopy. The filaments were composed of Gram-positive, rod-shaped cells, 1–2 μm in length and about 0.5 μm in breadth, attached end to end. Septa between cells were complex, with a central, electron-dense sheet which had a spherical enlargement in the center separating the cell walls. The cells walls themselves were of variable thickness with a light, fluffy, thin portion on the outside and a denser, thicker portion within. They contain a series of rings stacked side by side which are composed of material that stains strongly and positively with phosphotungstate ion. The cytoplasmic membrane of these cells had an outer leaflet which stains more densely with uranium and lead ions than the inner leaflet. There were no recognizable organelles in the cytoplasm other than ribosomes. It is shown in these observations that the presumed methanogen may likely be a new species.
Etude des polypeptides de structure du virus iridescent de Chilo suppressalis (Iridovirus type 6)
Authors: Barray Sylvie , DeVauchelle Gerard
Published: April 2010

We report a procedure for the purification of Chilo iridescent virus (Iridovirus type 6), an evaluation of the purification procedure, and the results of analyses of the virion proteins by acrylamide gel electrophoresis. Purity was evaluated in three ways, i.e., by analysis of purified virions from artificial mixtures of infected and labeled uninfected larvae, electrophoresis at neutral pH, and electron-microscopic examination. Analysis of the polypeptides of purified CIV gave the following results: (i) after solubilization with SDS-B-mercaptoethanol, 16 polypeptides could be resolved in Coomassie brillant blue-stained electrophoretograms with molecular weights ranging from 18 000 to 115 000; (ii) after solubilization with SDS-urea, 26 polypeptides could be resolved with molecular weights ranging from 10 000 to 230 000 daltons.
An agar–gel immunodiffusion test for detection of Brucella antibodies in human serum
Authors: McMahon K. J. , Renner E. D. , Allmaras G. W. , Anderson D. K.
Published: April 2010

A comparison was made of results obtained with a Brucella agar–gel immunodiffusion (AGID) test and the standard tube-agglutination test on 612 human sera. Agreement between the tests was 97% when the titer was 1:160 or higher. Of 448 sera that showed no agglutination titer, 447 were negative with the AGID test. Results of the AGID test were also compared to those obtained with the 2-mercaptoethanol (2-ME) agglutination test on 148 sera that demonstrated a standard tube-agglutination titer of 1:20 or higher. All sera with a 2-ME-agglutination titer of 1:40 or higher were positive with the AGID test. Of 123 sera that showed no 2-ME-agglutination titer. 21 were positive with the AGID test. Two of these 21 sera were obtained from patients with bacteriologically proven brucellosis, and eight were from abattoir employees with suspected but not bacteriologically proven brucellosis.
Method for the rapid screening of cellulolytic streptomycetes and their mutants
Authors: Daigneault-Sylvestre N. , Kluepfel D.
Published: April 2010

A method for the rapid screening of cellulolytic streptomycetes and their mutants is reported. The technique consists of a plate assay on media containing filter paper fibres as cellulose substrate. The cellulolytic activity is detected and measured by the formation of clearing zones around the streptomycete colonies. The sensitivity of the method is increased considerably by subjecting the plates to an additional incubation period at 43 °C in the presence of a buffer at pH 5.3. By replicating these colonies on other Petri plates containing the appropriate media, it is possible to assess rapidly, not only the degree of catabolic repression of the cellulase production by glucose, but also, in a semiquantitative way, the amount of enzymes produced.