bluuebunny/crossref_metadata_2025 huggingface dataset:
Accroissement par Staphylococcus aureus de la résistance de la souris envers l'infection par Pseudomonas aeruginosa
Authors: deRepentigny J. , Mathieu L. G. , Coallier-Ascah J.
Published: April 2010

In our study of opportunistic pathogens, we have some indication that Staphylococcus aureus can increase resistance in mice against Pseudomonas aeruginosa. Intraperitoneal injections of sublethal doses of S. aureus had a protective effect in mice against lethal doses of P. aeruginosa, more so if living and coagulase-positive S. aureus strains were injected. This protective effect was obtained both with laboratory and freshly isolated hospital strains. The interval between these infections can be extended from 2 h up to 1 week and it is still possible to observe the resistance phenomenon. The increased resistance was accompanied by a decrease in viable units of P. aeruginosa in the peritoneal cavity of mice 6 h after the injection of this species. There was no protection by S. aureus against Candida albicans in similar experimental conditions. These observations indicate that intermicrobial ecology, understood here as the previous presence of another species in a host, may be a significant factor in the resistance to infection with opportunistic pathogens such as P. aeruginosa.
Effect of volatile inhibitors from natural and amended soils on germination of sclerotia of Macrophomina phaseolina
Authors: Papavizas G. C.
Published: April 2010

Studies on volatile soil fungistasis showed that sclerotia of Macrophomina phaseolina are not sensitive to volatiles liberated by natural soils with varying pH values. Soil amended with alfalfa hay (1%, w/w) liberated volatiles fungistatic to sclerotia only when the assay was performed 2 weeks or less after amendment. Chitin-amended soils liberated fungistatic volatiles from 1 to 3 weeks after amendment. Indirect evidence indicated that ammonia may be the active volatile in amended soil. It was concluded that fungistatic volatiles may not play an important role in the survival of sclerotia in nature.
Etude par immunoélectrophorèse bidimensionnelle de la composition antigénique de la membrane de quelques souches de mycoplasmes
Authors: Wroblewski Henri , Ratanasavanh Damrong
Published: April 2010

Membrane antigenic composition of Acheloplasma laidlawii PG 9, A. granularum BTS-39, and Mycoplasma fermentons PG 18(G) was determined by means of bidimensional immunoelectrophoresis in the presence of sodium desoxycholate 0.5%. Depending upon the mycoplasma species from which membranes were obtained, 7 to 15 antigens were evidenced. Using sodium desoxycholate presents the advantage over non-ionic detergents to dissolve better the mycoplasma membrane antigenic complexes. A comparative study of five strains belonging to the above-noted species confirms the serological heterogeneity of the Mycoplasmatales order and shows variability at the membrane antigenic composition level of Acheloplasma laidlawii. [Translated by the journal]
Site of action of nonheme iron in the malate (flavine adenine dinucleotide) pathway of Mycobacterium phlei
Authors: Tyagi A. K. , Reddy T. L. Prasada , Venkitasubramanian T. A.
Published: April 2010

Irradiation with ultraviolet light (360 nm) of cell-free extracts, electron-transport particles, and soluble components from Mycobacterium phlei resulted in the loss of malate oxidation by the flavine adenine dinucleotide pathway both in cell-free extracts and reconstituted systems. Addition of vitamin K1 restored the loss to the extent of 14% and 11% in cell-free extracts and reconstituted systems respectively. Electron-transport particles from M. phlei upon reduction with malate exhibited electron-paramagnetic resonance signals at g = 2.002 and 1.94, characteristic of napthosemiquinone and nonheme iron protein, respectively. Upon irradiating the particles with ultraviolet light (360 nm) these signals were not observed. Particulate flavine-adenine-dinucleotide-dependent malate dehydrogenase (EC 1.1.1.37) of M. phlei assayed by the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide and phenazine methosulfate–2,6-dichlorophenolindophenol systems, which trap electrons at cytochrome c and at the flavine level respectively, was inhibited by o-phenanthroline. These observations suggest that nonheme iron protein is sensitive to ultraviolet light (360 nm) and participates before or in combination with flavine in the malate (flavine adenine dinucleotide) pathway of M. phlei.
Bacterial degradation of ethylene and the acetylene reduction test
Authors: Debont J. A. M.
Published: April 2010

The basic assumption that ethylene is not degraded during the acetylene reduction test was found to be valid for the systems tested. Acetylene inhibited ethylene degradation by both pure cultures and soil, while acetylene-utilizing bacteria did not co-oxidize ethylene.
Characterization of group A streptococcal M-proteins purified by two methods
Authors: Straus David C. , Lange Charles F.
Published: April 2010

Ten different group A streptococcal M-protein preparations purified by trichloroacetic acid precipitation and three M-protein preparations purified by cellulose chromatography were examined by SDS and polyacrylamide gel electrophoresis, and analyzed for amino acid composition and N-terminal amino acids. Fingerprinting (both tryptic and chymotryptic) was performed on the cellulose-purified preparations of M1, M12, and M29 proteins which showed these proteins to be structurally related. Trypsin produced maps with 37 to 42 peptides, whereas chymotrypsin digestion resulted in 8 to 12 peptides, depending on the M-type. Sequencing was performed on the M12 protein and tentative identification of nine N-terminal amino acids was made. Molecular weights of the cellulose and TCA-purified M-proteins were determined by SDS gel electrophoresis and chromatography on G-200 Sephadex, with comparable results, indicating molecular size of at least 23 000. The amino acid analyses of the 10 TCA-purified proteins followed the patterns established for M-proteins, with high concentrations of lysine, aspartic acid, glutamic acid, alanine, and leucine. All 10 proteins had L-alanine as their N-terminal amino acid. Evidence for a one way cross-reaction between type 1 and type 29 streptococci was also found.
Regulation by zinc and adenosine 3′,5′-cyclic monophosphate of growth and citric acid accumulation in Aspergillus niger
Authors: Wold William S. M. , Suzuki Isamu
Published: April 2010

The citric acid fermentation by Aspergillus niger is divided into two consecutive phases, growth phase when the cells proliferate but do not accumulate citrate, followed by an accumulating phase when they excrete citrate but do not proliferate. The phase alternative was controlled by the concentration of zinc: high zinc (2 μM) maintained growth phase, and a zinc 'deficiency apparently signaled the transition to the accumulating phase. Cyclic AMP affected the rates of growth and acidogenesis when added to cultures growing at low but not at high zinc: that is, cAMP did not induce the phase transition, zinc deficiency did. Cyclic AMP enhanced growth early in the fermentation, but at later stages the response of the mycelia to cAMP changed, and then cAMP inhibited growth. When citrate eventually began to accumulate cAMP augmented its synthesis. The growth and acidogenic responses were quite specific to cAMP, and were sensitive to concentrations of about 1 μM. Cyclic AMP also either promoted or retarded the appearance of an unidentified yellow pigment. It is proposed that the growth and accumulating phases are distinct differentiated states, at least with respect to cAMP metabolism.
The ultrastructure of the Spilocaea state of Venturia inaequalis in vivo
Authors: Corlett Michael , Chong James , Kokko E. G.
Published: April 2010

There are indications that the fungus enzymatically degrades the cuticle and epidermal cell wall. The epidermal cells and to a lesser degree the palisade mesophyll cells beneath a sporulating lesion (susceptible reaction) are killed or seriously disrupted. Various stages of conidiogenesis, including development of the primary conidium, were observed. A conidium is delimited by a two-layered transverse septum. Before conidium secession, a new two-layered inner wall is laid down around the entire conidiogenous cell adjacent to the plasmalemma. The apical region of the new inner wall proliferates beyond the annellation scar left by the seceded conidium and eventually produces another conidium.
A cellulase complex in culture filtrates of Penicillium citrinum
Authors: Olutiola P. O.
Published: April 2010

During growth in a liquid medium that contained a single soluble or an insoluble cellulosic carbon source Penicillium citrinum released a complex of cellulase enzymes into the medium. A temperature of 30 °C was best for cellulase production. Presence of carbon-containing compounds, particularly glucose, inhibited cellulase activity. The enzyme complex was separated by gel filtration followed by ion-exchange chromatography into 11 components, 4 of high molecular weight and 7 of low molecular weight. One of the components (Bb) had the character of C1 cellulase enzyme. When the components were combined they released more reducing sugars from cullulosic substrates than when they were used singly.
Phagocytic and chlamydiae-inhibiting activities of stimulated and nonstimulated peritoneal mouse macrophages
Authors: Kordová Nonna , Wilt John C.
Published: April 2010

Phagocytic and chlamydiacidal properties of nonstimulated and stimulated mouse mononuclear cells for two Chlamydia psittaci 6BC strains were investigated. It was determined that macrophages kept in monolayer culture (i.e. stimulated phagocytes) developed much more efficient chlamydiacidal ability than did cells kept in suspension directly after harvest (i.e. nonstimulated phagocytes). A thousandfold decrease of chlamydial infectivity was observed 60 min after induction of phagocytosis in stimulated macrophages, irrespective of the strain offered. In contrast, the infectivity of both chlamydial strains remained essentially unchanged up to 1 h after phagocytosis by nonstimulated phagocytes. Electron-microscopic examination indicated that chlamydiae were disintegrated within phagolysosomes of stimulated phagocytes within minutes after phagocytosis, although ultrastructurally altered chlamydiae not enclosed in vacuoles were also observed in the cytoplasm of several mononuclear phagocytes at different times after phagocytosis.
Speculations on a possible essential function of the gelatinous sheath of blue-green algae
Authors: Lange Willy
Published: April 2010

Voluminous and often fluffy sheaths surrounding blue-green algal cells are observed (a) in productive natural waters, (b) in bacteria-containing laboratory cultures growing in inorganic nutrient media with added bacteria-assimilable organic matter, and (c) in axenic cultures in the same inorganic media even without added organic matter. The sheaths of bacteria-associated species in inorganic media without added organic matter are, by comparison, thin, and growth is meager. Repeated observations show that voluminous sheaths and vigorous growth of algal species are associated. It is suggested that formation and retention of a voluminous sheath provide a microenvironment around the algal cell where essential nutrients, present at only submarginal levels in the surrounding water, are concentrated and become readily available to the cell. This increase in nutrient concentration above a critical level, in turn, leads to vigorous algal growth. The voluminous sheath produced by the alga is not attacked by alga-associated bacteria when other assimilable organic matter is available: but in the absence of a more suitable food, the bacteria feed on the less desirable gelatinous sheath, markedly reducing its thickness and causing meager algal growth.
Magnesium requirement of Staphylococcus aureus for repair from sublethal heat injury
Authors: Hughes Ashton , Hurst Andre
Published: April 2010

Heating in potassium phosphate buffer causes Staphylococcus aureus to lose its salt tolerance and 30–40% of its cellular Mg2+. Repair from injury (regain of salt tolerance) occurred when injured cells were incubated under optimal conditions in synthetic media containing penicillin to prevent growth. Cells died when phosphates or amino acids were omitted from the medium. Omission of vitamins, glucose, Na+, and K+ had no effect. Omission of Mg2+ diminished repair. In a minimal repair medium (MRM) which contained only 3 × 10−6 M Mg (as an impurity), injured cells rapidly regained their original Mg content. About 20–50% of the cells also regained their salt tolerance provided that less than 109 cells/ml were used. With 1010 cells/ml there was no repair and cellular Mg content was half that of the control. Addition of 10−3 M ethylenediaminetetraacetic acid (EDTA) to MRM also prevented repair. Addition of 10−2 M Mg to MRM + 10−3 M EDTA permitted complete repair.
Polymorph-mediated antibody-dependent cytotoxicity—modulation of activity by drugs and immune interferon
Authors: Wardley Richard C. , Babiuk Lorne A. , Rouse Barry T.
Published: April 2010

Bovine polymorphonuclear leukocytes (PMN) mediated antibody-dependent cell cytotoxicity (ADCC) against erythrocyte and herpes virus-infected target cells. The extent of cytotoxicity was not affected by drugs that inhibited DNA, RNA, or protein synthesis. The effect did not occur in the absence of divalent cations, was suppressed by pretreatment of PMN with silica and cytochalasin B, and was subject to the bidirectional control by cyclic nucleotides: drugs decreasing cyclic AMP or elevating cyclic GMP levels enhanced ADCC. The ADCC phenomena was also enhanced by supernates containing immune interferon activity from antigen-stimulated-immune lymphocyte-macrophage cultures. The possibility that immune interferon(s) might be causing the elevation of ADCC and the relevance of this observation in terms of the part interferon might play in modulating recovery from herpes virus infections was discussed.
Clostridium botulinum type C: 1. Sélection d'une population bactérienne hautement toxinogene au sein d'une culture pure
Authors: Vinet Guy , Daigneault Nicole
Published: April 2010

When transplanted repeatedly at 37 °C, the strain Clostridium botulinum type C exhibits the tendency to lose its toxigenic activity. Two types of colonies are identified on agar medium. The morphology of these colonies is closely related to their ability to synthesize the toxin.
Procedures for obtaining sectional views of fungal fructifications by scanning electron microscopy
Authors: Brown M. F. , Brotzman H. G.
Published: April 2010

Procedures for sectioning fungal fructifications in host tissues or on artificial media are described, which allow observation of internal structures by scanning electron microscopy. Perithecia of Ceratocystis fimbriata and Phyllachora graminis, and telia of Puccinia xanthii showed excellent preservation of exposed structures in sections which were osmium-coated before being dried. While similar preservation was obtained in sectioned acervuli of Lecanosticta acicola and Marssonina juglandis and in pycnidia of Dothiorella ribis and Phomopsis occulta, the mucilaginous substances produced in these fructifications precluded observation of conidiophores. Extraction of mucilage from these sections was accomplished by periodic acid and dilute KOH treatments, followed by an osmium-coating procedure. In such preparations, mucilage was removed, internal structures were preserved, and pertinent characteristics of conidiogenous cells were resolved.
Some properties of p-coumarate decarboxylase from Cladosporium phlei
Authors: Harada T. , Mino Y.
Published: April 2010

The optimal pH and temperature of p-coumarate decarboxylase were 6.0 and 23 °C, respectively. The enzyme activity was reduced to three quarters by heat treatment at 35 °C for 5 min and by half at 25 °C in 24 h, but kept almost unchanged at −20 °C at least for l0 days. The activity was not inhibited by potassium cyanide, sodium diethyldithiocarbamate, ethylenediaminetetraacetic acid disodium salt, or sodium citrate at 10 mM concentration, but was inhibited by p-chloromercuribenzoate or iodoacetate at 0.1 mM, the inhibition by the former being prevented to a great extent by the presence of reduced glutathione or dithiothreitol. The activity was inhibited by maleic acid, cinnamic acid, or p-methoxycinnamic acid, but not by fumaric acid, acrylic acid, p-hydroxystyrene, furcatin, p-hydroxyphenylacetic acid, or phloretic acid. An unsubstituted p-hydroxy group on the benzene ring and an acrylic acid side chain were required for the enzyme activity. Km value for trans- p-coumaric acid was about 6.5 × 10−4 M.
Sexual hormone in the cellular slime mould Dictyostelium purpureum
Authors: Lewis Keith E. , O'Day Danton H.
Published: April 2010

The existence of sexual hormone in Dictyostelium purpureum was revealed when the extracellular medium from certain strains (Dp6 or Dp7) induced macrocyst formation when added to cells of the opposite mating type (Dp2). Our results suggest that mating in cellular slime moulds may involve a secreter–responder system whereby one mating-type strain (Dp6 or Dp7) releases sexual hormone while the opposite strain (Dp2) responds. However, the existence of a hormone released by the responding strain has not been completely ruled out by our experiments. The sexual hormones of cellular slime moulds appear to be species-specific since hormone from D. purpureum cannot induce macrocyst formation in responder strains of D. discoideum and hormone from D. discoideum has no effect on D. purpureum cells.
Bacteriorhodopsin formation in Halobacterium halobium
Authors: Hubbard Jerry S. , Rinehart Clifford A.
Published: April 2010

Systematic examinations were made of factors influencing bacteriorhodopsin formation during the growth of Halobacterium halobium. Light-induced adenosine triphosphate (ATP) production and [14C]proline uptake were used as measures of functional ability of the purple membrane. Maximum bacteriorhodopsin formation occurred under growth conditions of illumination and limited aeration. The purple membrane – ATP production system did not confer an appreciable growth advantage. Growth in the dark or with adequate aeration partially suppressed bacteriorhodopsin formation and the effects were additive. Nicotine effectively inhibited bacteriorhodopsin formation. A rapid synthesis of functional pigment occurred when washed suspensions of cells which had been grown under illumination with nicotine present were incubated under dark, aerobic conditions. The alleviation of this nicotine inhibition was not blocked by chloramphenicol or bacitracin. Bacteriorhodopsin formation was negligible when washed suspensions of cells from dark, limited aeration or light, adequate aeration cultures were incubated in the light with limited aeration. A nutritionally complex medium was needed to elicit appreciable bacteriorhodopsin formation by the cells from the dark or adequately aerated cultures. Bacitracin partially inhibited this bacteriorhodopsin formation by cells from the light, adequately aerated culture.
The isolation and characterization of gliding motility mutants of Myxococcus xanthus
Authors: MacRae Thomas H. , McCurdy Howard D.
Published: April 2010

Nonmotile and motility-altered mutants of Myxococcus xanthus have been obtained by the use of chemical mutagens, ultraviolet irradiation, and a procedure for selecting spontaneous mutants. As judged by their behaviour on a variety of growth media, in both plate and slide culture, the mutants were divided into four groups. One group contains mutants which are truly nonmotile. Myxococcus xanthus NM, previously described as a nonmotile mutant, may be similar to type 3 mutants (described in text).
Deoxyribonucleic acid studies in the genus Caryophanon
Authors: Adcock Kim A. , Seidler Ramon J. , Trentini W. C.
Published: April 2010

The deoxyribonucleic acid (DNA) of 36 isolates of Caryophanon latum and 3 isolates designated Caryophanon tenue, obtained from geographically diverse regions, has been examined for guanine plus cytosine (mol % G + C) base composition, genome size, and for relative reassociation levels. The isolates were found to be homogenous and group-specific in their base composition, with C. latum DNA ranging from 44.0 to 45.6 mol % G + C, and C. tenue from 41.2 to 41.6 mol % G + C. Genome size determined for representative isolates confirmed the distinction of the two groups. The genome size ranged from 1100 to 1200 × 106 daltons for C. latum and from 900 to 1000 × 106 daltons for C. tenue. DNA:DNA hybridization studies revealed relative reassociation levels as follows: C. latum to C. latum, 78–94%, C. tenue to C. tenue, 82–94%; and C. latum to C. tenue, 13–30%. Finally, based on genome size and mol % G + C similarities, DNA:DNA hybridization experiments between two strains of Lactobacillus and C. latum and C. tenue were performed. These experiments revealed essentially no polynucleotide sequence similarity between the Lactobacillus and Caryophanon isolates used.
Respiratory activity as a determinant of radiation survival response
Authors: Bruce A. K. , Berner John D.
Published: April 2010

Respiration is depressed in irradiated bacteria reaching a minimum level in most strains at 1–3 h after exposure when incubated in growth medium. Since a delay in response is observed, direct action on respiratory enzymes is unlikely. The dosage response of respiration varies widely in the strains studied with D0's from 15 kR for Escherichia coli Bs−1 to 1200 kR for Micrococcus radiodurans. All strains exhibit two-component dosage–response curves. Escherichia coli Bs−1 uniquely possesses a positive-sloped second component suggesting a major disruption of respiratory control. A relationship exists between the responses of respiration and survival to a 50-kR exposure in the strains studied. When E. coli B/r is grown in 0.4% glucose reaching a pH of 5.3, a condition known to increase radiation survival considerably, a large increase in radioresistance of respiration is found. 2-Mercaptoethylamine (MEA), a radioprotective agent, also produces proportionate radioprotection of respiration and survival. In M. radiodurans protection is afforded to respiration at doses which produce no measurable effect on survival. These facts suggest that respiration is a major factor in influencing cell survival and may be the principal mechanism through which chemical agents modify radiation response.
Degradation of [14C]photodieldrin by Trichoderma viride as affected by other insecticides
Authors: Tabet J. C. K. , Lichtenstein E. P.
Published: April 2010

Various soil fungi were tested for their capacity to degrade the insecticide [14C]photodieldrin. Of nine species investigated, Trichoderma viride was the only one which degraded the insecticide to an appreciable extent into water-soluble, non-insecticidal compounds within 4–5 weeks. These products amounted to 32–41% of the radiocarbon applied to the culture media. The degradation was a function of live mycelia, which metabolized the insecticide and excreted water-soluble compounds into the culture media. Since soils usually contain a mixture of pesticide residues, the effects of several chlorinated hydrocarbon insecticides on the capacity of the fungus to degrade [14C]photodieldrin were studied. Thus, in fungal cultures treated with compounds structurally similar to photodieldrin, such as aldrin and dieldrin, only 4–17% of the applied radiocarbon was water-soluble and more photodieldrin remained. In controls, however, 35% of the applied radiocarbon was in the form of water-soluble products and less photodieldrin remained. The degradation of [14C]photodieldrin by T. viride, with time, was associated with a continuous decline of hexane-soluble radiocarbon and a steady increase of water-soluble metabolites, which appeared in the fungal media. The amount of hexane-soluble radiocarbon in mycelia was directly related to the fungal mass.
Besoins en phosphore des bactéries métabolisant les hydrocarbures en mer
Authors: Petit J. Le , N'Guyen M.-H.
Published: April 2010

The artificial stimulation of biological purification of sea-pollutant hydrocarbons requires phosphorus supply. The concentrations, corresponding to the optimal bacterial growth, depend, in particular, on ionic strength. They range between 2 and 8 × 10−4 M for waters in which the salinity is close to the mean salinity of an oceanic environment and between 1.5 and 3 × 10−3 M when these waters receive a significant supply of freshwater or when salinity is naturally weak. Inhibition of bacterial development has been observed either with a microflora, or with pure strains for concentrations higher than the upper limits of concentrations so defined.
Roles of low pH, carbon and inorganic nitrogen source use in chlamydospore formation by Fusarium solani
Authors: Griffin Gary J.
Published: April 2010

Citrate and malate were poorer sources of exogenous carbon than several hexose, pentose, or disaccharide sugars for supporting macroconidial germination by Fusarium solani at high conidial density (1 × 105 conidia/ml). Only citrate, however, failed to block chlamydospore morphogenesis to a degree comparable to glucose or other readily used sugars. Mostly immature chlamydospores were formed in the presence of citrate. At low conidial density (5 × 103 conidia/ml), exogenous carbon-independent macroconidial germination and subsequent rapid chlamydospore formation on germ tubes was not inhibited by ammonium or nitrate nitrogen. The citrate–phosphate buffered, low pH (4.0) medium of Cochrane induced more immature chlamydospore formation by F. solani than a pH 6.0 medium, but few mature chlamydospores were formed in either medium. Condensation of hyphal cytoplasm into developing chlamydospores, a character typical of chlamydospore formation, did not occur extensively and macroconidia, hyphae, and immature chlamydospores stained deeply with Sudan III, suggesting lipid biosynthesis. This inhibition of chlamydospore maturation may be due partly to nitrogen deficiency imposed by the high C: N ratio of the medium and to the presence of citrate. Only vesiculate hyphal cells were formed by F. solani f. sp. phaseoli in both media.Field soils to which the clone of F. solani used is indigenous had mean pH values ranging from 5.2 to 6.0.
The effect of gravitational forces on the viability of spheroplasts of mycobacteria
Authors: Ratnam Samuel , Chandrasekhar Saroj
Published: April 2010

Spheroplasts of Mycobacterium smegmatis and Mycobacterium tuberculosis were subjected to a wide range of centrifugal forces ranging from 583 g to 15 000 g after which their viability was determined by plating them on two types of media; one containing stabilizing agents and the other without them. Though there were minor fluctuations in the viable counts, there was no consistent decrease in their viability even in the absence of osmotic stabilizers.
Characterization of a strain of Methanospirillum hungatii
Authors: Patel G. B. , Roth L. A. , Berg L. van den , Clark D. S.
Published: April 2010

The results of morphological, base ratio, nutritional, temperature, and pH studies on a strain of Methanospirillum hungatii, isolated from an anaerobic pear waste digester, are described. The isolate, designated as strain GP 1, was compared with some of the characteristics of type-strain M. hungatii JF 1. Strain GP 1 is Gram-negative, weakly motile, and a strict anaerobe with a guanine plus cytosine (G + C) content of 46.5 mol%. The preferred substrates for methane production are hydrogen, carbon dioxide, and formate. Acetate is used under certain conditions but its specific contribution to cell carbon and (or) methane formation was not established. The optimum temperature for both growth and methane production is 35 °C, but growth and methane production occur over the range 25–45 °C. Methane production is optimal at pH 7.0.
Anomalous aggregation of Clostridium perfringens enterotoxin under dissociating conditions
Authors: Enders Jr. George L. , Duncan Charles L.
Published: April 2010

Polyacrylamide gel electrophoresis of highly purified Clostridium perfringens enterotoxin revealed electrophoretic microheterogeneity of the enterotoxin, apparently because of slight charge differences in the peptides. Detergent gel electrophoresis showed that purified enterotoxin formed high molecular weight aggregates in the presence of both sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide. No conditions capable of inhibiting this phenomenon were found. Although a molecular weight of 35 000 daltons has been reported in the literature, the experimentally determined molecular weight values in the presence of detergents corresponded to multiples of a theoretical subunit molecular weight of 17 500 daltons. Binding studies performed by equilibrium dialysis and ultracentrifugation methods revealed that the enterotoxin bound very small amounts of SDS per gram of protein. The evidence presented indicates possible detergent induced structural alterations of the protein.
Endosymbionts of Sitodrepa panicea
Authors: Bismanis J. E.
Published: April 2010

Morphological and physiological characteristics of seven strains of yeast-like symbionts isolated from Sitodrepa panicea justify their, inclusion into the genus Torulopsis as a new species: T.buchnerii. The symbiotic relationship is mutually beneficial: the symbionts obtain some nitrogenous compounds and carbohydrates, such as proline and trehalose from the host's hemolymph, and synthesize and make available to the host all the essential amino acids and vitamins, except biotin.
The release and characterization of some periplasm-located enzymes of Pseudomonas aeruginosa
Authors: Bhatti A. R. , DeVoe I. W. , Ingram J. M.
Published: April 2010

Pseudomonas aeruginosa (ATCC 9027) releases four periplasm-located enzymes, i.e., ribonuclease (EC 3.1.4.22; EC 3.1.4.23), alkaline phosphatase (EC 3.1.3.1), cyclic-2′, 3′-phosphodiesterase (EC 3.1.4.d), and 5′-nucleotidase (EC 3.1.3.5) into the medium during growth. Ribonuclease and alkaline phosphatase are classed as enzymes which are readily extracted by osmotic shock and spheroplast formation whereas cyclic-2′,3′-phosphodiesterase and 5′-nucleotidase are classed as enzymes which are not readily extracted by these procedures. In view of the relative ease of extraction of the former enzymes it is suggested that the latter enzymes, cyclic-2′,3′-phosphodiesterase and 5′-nucleotidase, are bound and located in the periplasm in a manner different to ribonuclease and alkaline phosphatase.
Extracellular nuclease produced by a marine bacterium. I. Extracellular deoxyribonuclease formation by a marine Vibrio sp.
Authors: Maeda M. , Taga N.
Published: April 2010

Deoxyribonuclease (DNase) activity was found in the culture fluids of numerous marine bacteria isolated from seawater. Among these organisms, marine bacterium, Vibrio sp., strain No. 2, showed the highest deoxyribonucleic acid – hydrolyzing activity. This organism requires salts of seawater for both growth and extracellular DNase formation. The DNase activity could not be detected in the synthetic seawater culture liquid lacking magnesium ion, and DNase activity decreased in a calcium-deficient medium. The optimum temperature for the growth of this organism was between 15 and 25 °C. The formation of extracellular DNase was the greatest at 20 °C and less activity was found at 10 and 30 °C.
Comparison of vesicular stomatitis virus defective interfering particle synthesis in chick embryo and L cells
Authors: Potter Kathleen N. , Stewart Robert B.
Published: April 2010

A comparison of the ability of vesicular stomatitis virus (VSV) to generate and replicate defective interfering (DI) particles in primary chick embryo (CE) and mouse L cells was investigated as a means of analyzing host control over DI-particle synthesis and interfering capacity. Serial undiluted passage of VSV in CE and L cells indicate that VSV-DI particles are generated and (or) replicate with greater efficiency in CE than in L cells. When DI particles accumulate in L cells, they are able to interfere with infectious particle replication. The DI particles from CE cells interfered to the same extent with infectious particle replication in both CE and L cells. L cells, therefore, are not considered 'low-interference' hosts in which DI particles are produced and do not interfere with infectious virus replication, but rather hosts which restrict the production of DI particles.
Long-term cultures of chick embryo fibroblasts transformed by the Schmidt–Ruppin strain (D) of Rous sarcoma virus
Authors: Leblond-Larouche Lorraine , Morais Réjean
Published: April 2010

Attempts have been made to keep in vitro, for extended periods of time, cultures of chick embryo fibroblasts transformed by the Schmidt–Ruppin strain of Rous sarcoma virus, subgroup D. Roller cultures of transformed chick cells kept in serum-deficient medium can be maintained without subcultivation for up to 6 months. The confluent cultures continuously release viruses and viable tumor cells into the medium. The released cells can be plated and have characteristics of growth and morphology which are relatively stable with time until the culture degenerates. Cells released at later stages of the culture produced substantially more viruses than those released earlier, suggesting that cell selection or differentiation occurs during long-term cultivation in low serum concentration. Long-term cultures of untransformed chick embryo fibroblasts can also be maintained in the same way. The release of viable cells by these confluent cultures, however, is negligible.
Isolation and characterization of nocardia-like variants of Mycobacterium smegmatis
Authors: Hawley R. J. , Imaeda T. , Mann Nora
Published: April 2010

Orange-red-pigmented (OR) colonies were isolated from cream-yellow-pigmented Mycobacterium smegmatis after exposure to either mycobacteriophage MC4 or ultraviolet light; these variant strains were designated OR4 and ORuv, respectively. Early subculture of OR-colonies did not show any segregation of parental-type cells. However, colonies resembling the parental strains, possibly representing a back mutant (REV-OR4), were occasionally found during subculture of established OR-colonies or upon treatment with N-nitroso-N′-nitro-N-methylguanidine. The OR-variants were characterized by their lytic response to nocardiophage, but not to mycobacteriophages, presence of α-branched, β-hydroxylated fatty acids of the Nocardia-type, and a guanine plus cytosine value of deoxyribonucleic acid (DNA) between 62 and 64 mol %. They were more resistant to the lethal action of both ultraviolet light and mitomycin C treatment than the parental and back mutant strains.Although the OR-variants in this study possess characteristics common to the genus Nocardia or some of the 'rhodochrous' mycobacteria, evidence is presented that they form a new class of mycobacterial variants.
Lactate dehydrogenase from autotrophic and heterotrophic cells of the marine diatom Cylindrotheca fusiformis Reimann & Lewin
Authors: Darley W. Marshall , Smiley Richard H.
Published: April 2010

Cultures of Cylindrotheca furisormis grown either autotrophically or heterotrophically on lactate contained significant amounts of NAD-dependent L(+)-lactate dehydrogenase (EC 1.1.1.27). Polyacrylamide gel electrophoresis of crude enzyme extracts revealed a single band which was indistinguishable between autotrophic and heterotrophic cells. The Km for lactate of partially purified preparations was lower under heterotrophic conditions. The specific activity in crude extracts was higher under autotrophic than heterotrophic conditions; it dropped precipitously when autotrophic cells were transferred to the dark, increasing again only in the presence of lactate. These and related observations suggest that this enzyme has at most only a minor role in the assimilation of lactate during heterotrophic growth on lactate.
Influence of temperature on growth of lipopolysaccharide-deficient (rough) mutants of Salmonella typhimurium and Salmonella minnesota
Authors: Chatterjee Arun K. , Sanderson Kenneth E. , Ross Helen , Schlecht S. , Lüderitz Otto
Published: April 2010

Smooth strains of Salmonella typhimurium and S. minnesota, and chemotypes Ra, Rb, and Rc, which are deficient in lipopolysaccharide components of the somatic side chains and outer core region, grow normally on nutrient agar and nutrient broth up to 45 °C. However, most mutants with defects in the heptose region of the LPS (chemotypes Rd2 and Re) do not grow on this medium at 42 °C or above; a few grow at 42 °C but not at 45 °C. In liquid medium (nutrient broth, or phosphate minimal medium), growth, measured as turbidity or as colony-forming units, stops 60 to 90 min after shift from 30 to 42 °C; DNA and protein synthesis cease at the same time. Growth does not reoccur at 42 °C; protein synthesis and growth reinitiate upon shift to 30 or 37 °C. Growth cessation does not alter cell morphology in the phase-contrast microscope. Growth of heptose-deficient strains at 42 °C in nutrient broth is restored by MgCl2 (0.5 mM), NaCl (50 mM), or sucrose (100 mM). Sensitivity to smooth-specific and rough-specific phages, and analysis of LPS composition, indicate that heptose-deficient mutants grown at temperatures from 30 to 45 °C, and in the presence or absence of high salt, do not contain heptose or O-specific sugars in their LPS.
Investigations of nitrogenase activity in rheotrophic peat
Authors: Waughman George John
Published: April 2010

Acetylene reduction by the peat microflora was unaffected by light, but was sensitive to temperature, with an optimum of about 30 °C. The nitrogenase was inactivated by exposure to temperatures above about 35 °C. Activity occurred in completely anaerobic conditions; the rate of ethylene production was of the order of 0.5 nmol C2H4 ml−1h−1. Experiments with time courses indicated that exposure to oxygen caused an initial inhibition of activity followed by a period in which ethylene production was stimulated to rates much higher than in the anaerobic tests; both the inhibition and stimulation appeared to be related to the level of oxygenation. It is suggested that these results could be explained by the existence of nitrogen-fixing associations of aerobic and anaerobic bacteria in the peat. The stimulation of activity caused by exposure to air indicates that care must be taken when interpreting results of the assay obtained from waterlogged organic soils.
Physical characteristics of DNA from bacteriophages of Agrobacterium tumefaciens
Authors: Manasse R. J. , Staples R. C.
Published: April 2010

DNA was extracted from isolates of bacteriophages grown on virulent and avirulent strains of Agrobacterium tumefaciens. Molecular weights of DNA from phages isolated from the virulent A. tumefaciens (IIBV7) were about 41.5 × 106 daltons, while those from the avirulent A. tumefaciens (IIBNV6) were about 32.5 × 106 daltons. The buoyant densities of the four DNA's ranged from 1.7086 to 1.7089 g/cm3 values that were not significantly different. DNA–DNA hybridization studies also indicated that the four phages were closely related. Attempts to induce tumors with phage DNA were unsuccessful.
Comparison of four eluents in the recovery of indigenous viruses from raw sludge
Authors: Sattar S. A. , Westwood J. C. N.
Published: April 2010

The efficiency of 3% casein hydrolysate (CH), 3% lactalbumin hydrolysate (LH), 3% beef extract (BE), and 10% fetal calf serum (FCS) was compared for the recovery of viruses from raw sludge. CH and LH proved to be inefficient and were eliminated from the study after initial testing. In tests with 20 different samples of raw sludge, beef extract eluted virus in 15 (75%) and FCS revealed virus in 19 (95%) of the samples using BS-C-1 cells.That different eluents were not eluting different viruses from the same sample was shown by the serologic and electron-microscopic examination of 43% (18/42) of the isolates. The identified viruses included members of the entero- (coxsackie B, and polio) and reo-virus groups.
Evidence for motility-related fimbriae in the gliding microorganism Myxococcus xanthus
Authors: MacRae Thomas H. , McCurdy Howard D.
Published: April 2010

An electron-microscopic examination of negatively stained preparations from cell lysates of Myxococcus xanthus and in situ samples of Myxococcus xanthus, Myxococcus virescens, and Myxococcus fulvus has demonstrated the presence of polar fimbriae, about 8.5 nm in diameter, on motile but not nonmotile cells.
Biosynthesis of lysine in Saccharomyces cerevisiae: properties and spectrophotometric determination of homocitrate synthase activity
Authors: Gray Gary S. , Bhattacharjee J. K.
Published: April 2010

A rapid assay is described for homocitrate synthase (EC 4.1.3.21) of the lysine biosynthetic pathway of Saccharomyces cerevisiae. The α-ketoglutarate-dependent cleavage of acetyl-coA was measured spectrophotometrically as decrease in absorbance at 600 nm in the presence of 2, 6-dichlorophenol-indophenol and enzyme from the wild-type strain X2180. This activity was also present in a citrate synthaseless glutamate auxotroph glu3, and the activity was inhibited by 5 mML-lysine. Radioactive homocitric acid was obtained from a reaction mixture containing [1-14C]acetyl-coA. Homocitrate synthase activity was dependent upon time, both substrates, and enzyme. The activity exhibited a pH and temperature optimum of 7.5–8.0 and 32 °C, respectively, and was inhibited by metal-chelating and sulfhydryl-binding agents.
Differentiation of pathogenic, gram-negative, bacterial genera in the presence of β-2-thienylalanine
Authors: Brown Kurt J. , Lines David R.
Published: April 2010

Described is a fast screening assay for aid in the differentiation of bacterial genera. Salmonella is separated from Escherichia and Shigella, as a generic group on the basis of an inhibition assay incorporating β-2-thienylalanine, and using a defined medium. The assay is also usable for confirmation of taxonomic differences between genera.The inhibition reaction, readable as an 'all-or-none' phenomenon, follows a dose-response relationship for cultures affected by β-2-thienylalanine, and is unaffected by the growth phase of the culture.
Lipid metabolism in Achlya: studies of lipid turnover during development
Authors: Law Simon W. T. , Burton David N.
Published: April 2010

The life cycle of Achlya involves germination of spores to form coenocytic somatic hyphae, followed by differentiation of hyphal tips into sporangia. From germination to release of new spores occupies 27–30 h. Total lipid made up 10% of dry weight in ungerminated spores. After germination, total lipid fell to 6% of dry weight in 15 h, then rose to7.7% at the time of sporangium formation. Half of the initial loss of lipid took place within 2 h of germination. The ability of Achlya to incorporate [1-14C]acetate into lipid was maximal at the time of sporangium formation, and glycerides were the principal component of total lipid to become 14C-labelled at all stages of the life cycle. Fatty acid synthetase activity measured in cell-free extracts was low in spores and in actively elongating mycelium, but increased during differentiation to a level 15-fold greater than that in spores. Fatty acid oxidation, as estimated by the release of 14CO2 from 1-14C-labelled fatty acids, was also maximal at the time of sporangium formation.
Lipid metabolism in Achlya: changes in lipid composition during development
Authors: Law Simon W. T. , Burton David N.
Published: April 2010

Fractionation of total lipid extracted from Achlya sp. at various stages of its developmental cycle revealed that in spores total lipid was composed of 62% neutral lipid, 13% phospholipid, and 25% glycolipid. After germination, the proportion of neutral lipid rose slightly after 2 h then fell sharply to 10% after 8 h, whereupon it rose to 55% of total lipid after 30 h of growth, when sporulation was completed. Conversely, phospholipid rose to 77% of total lipid after 8 h, then declined to 40% after 30 h. Glycolipid was maintained at 10–20% of total lipid throughout the life cycle after spore germination. Quantitative determination of neutral lipid components by photoreflectometry showed that triglycerides accounted for 20% of neutral lipid in spores, and free fatty acids made up 50%. During growth, the absolute levels of both components fell precipitously on germination, remained at low levels throughout vegetative growth, and rose at the time of sporulation.The fatty acid composition of total lipid, phospholipid, neutral lipid, and free fatty acid fractions extracted from vegetative and sporulating Achlya cells was determined. The principal fatty acids present in all fractions at both stages of the life cycle were hexadecanoic and octadecanoic acids. Hydroxyhexadecanoic acid, eicosatetraenoic acid, and an unidentified long-chain acid were completely absent from the phospholipids of vegetative cells, although they were found in significant quantities in lipid fractions from other stages of growth.
Identification of carbon dioxide as a dermatophyte inhibitory factor produced by Candida albicans
Authors: King Robert D. , Dillavou Clayton L. , Greenberg Joseph H. , Jeppsen Jay C. , Jaegar June S.
Published: April 2010

A factor produced by Candida albicans, which inhibits dermatophyte growth and induces arthrospore formation is characterized and identified. Candida dermatophyte inhibitory factor (CDIF) is volatile and fungistatic. Analysis of volatile materials produced by C. albicans was performed by gas chromatography. Only a single volatile substance was detected and was subsequently identified as carbon dioxide. The involvement of carbon dioxide in the inhibition of dermatophytes was demonstrated by: (1) utilization of commercial carbon dioxide to produce dermatophyte inhibition as well as arthrospore formation, and (2) prevention of dermatophyte inhibition by C. albicans through incorporation of soda lime into the incubation atmosphere. The ability of carbon dioxide to inhibit dermatophyte growth was shared with other gases (methane and helium), but arthrospore formation was observed only with carbon dioxide. The possible significance of carbon dioxide's induction of arthrospores, a form occasionally observed in active dermatophyte lesions, is discussed.
Isolation and characterization of a bacteriocin produced by Bacillus stearothermophilus strain NU-10
Authors: Yule Ronald , Barridge B. D.
Published: April 2010

Broth-grown cultures of Bacillus stearothermophilus strain NU-10 produce a bacteriocin which exerts lethal activity on other strains of the bacterium. Optimal production occurs during late maximum stationary phase of growth, at neutral pH, and 55–65 °C. The bacteriocin can be substantially purified by a combination of precipitations, centrifugations, and gel filtrations. The thermocin is composed of protein and carbohydrate. It is partially destroyed by proteolytic enzymes but is resistant to DNase, RNase, and various chemical treatments. The bacteriocin has a small molecular weight and exhibits considerable thermostability.
Dehiscence and active spore release in pathogenic strains of the yeast Metschnikowia bicuspidata var. australis: possible predatory implication
Authors: Lachance Marc-André , Miranda Mary , Miller Martin W. , Phaff Herman J.
Published: April 2010

Strains of Metschnikowia bicuspidata var. australis, pathogenic to brine shrimp (Artemia salina). were observed to form asci which, upon reaching maturity, forcibly expelled their needle-shaped spores. The mechanical force responsible apparently originates from the formation of an ectoplasmic mucilage capable of exerting pressure overall of the ascus contents; when the apex of the peduncle ruptures, the ascospores are violently released. Cytochemical analyses indicated that the gel is a substance highly resistant to chemical and enzymatic hydrolysis. Its chemical nature is not known as yet. The morphogenetic events of this process are described, and its ecological implication, the possibility of active mechanical predation in yeast, is discussed.