bluuebunny/crossref_metadata_2025 huggingface dataset:
A new nitrogen-fixing species of pseudomonad: Pseudomonas diazotrophicus sp. nov. isolated from the root of wetland rice
Authors: Watanabe I. , So Rolando , Ladha J. K. , Katayama-Fujimura Y. , Kuraishi H.
Published: May 2010

A new rod-shaped, Gram-negative, polarly flagellated, and facultatively chemolithotrophic nitrogen-fixing bacterium isolated from the roots of rice (Oryza sativa) was described. The bacterium fixed nitrogen (N2), used at least 55 organic compounds as sole carbon source, and did not require growth factors. It consisted of at least two distinct serogroups. The deoxyribonucleic acid base composition was 65.1–67.3 mol% G+C. The quinone system consisted of coenzyme Q10 as a major ubiquinone and coenzyme Q9 as a minor component. Cellular fatty acids consisted of 63–85% cw-9-octadecenoic acid, 7–10% octadecanoic acid, and 1–7% 3-hydroxytetradecanoic acid. These isolates are considered typical of a new species in the genus Pseudomonas and the proposed name is Pseudomonas diazotrophicus sp. nov.
Sexual co-flocculation and asexual self-flocculation of heterothallic fission-yeast cells(Schizosaccharomyces pombe)
Authors: Johnson Byron F. , Walker Teena , Miyata Machiko , Miyata Hisao , Calleja G. B.
Published: May 2010

Culturing conditions have been found that engender flocculation of strains 975h+ and 972h− of the fission yeast Schizosaccharomyces pombe Lindner. Both strains separately exhibit asexual self-flocculation and together, sexual co-flocculation. Flocculation is glucose repressible, but that repression is leaky, because self-flocculation can occur during the late logarithmic phase of growth before either of the C or N sources are depleted.
California serogroup and Powassan virus infection of cats
Authors: Keane D. P. , Parent J. , Little P. B.
Published: May 2010

One hundred and seventy five sera from cats in Ontario, Canada, were tested for hemagglutination inhibition (HI) antibodies to three arboviruses; namely, Powassan (POW) of the Flavivirus serogroup, and Snowshoe hare (SSH) and Jamestown Canyon (JC) viruses of the California (CAL) serogroup. All sera were negative for antibodies to POW virus. Twelve cats possessed CAL serogroup antibodies including 3 with antibodies to SSH alone, 6 with antibodies to JC alone, and 3 with antibodies to both SSH and JC antigens. POW virus was inoculated into seven cats, one intracerebrally and six intravenously. Neurologic signs were not detected in any of the cats. Histologic lesions of a nonsuppurative encephalitis and encephalomyelitis were observed in the intracerebrally inoculated cat and in one of the intravenously inoculated cats, respectively. POW virus was not isolated from the brain or spinal cord of either of these two cats. HI antibodies were detected in the sera of all inoculated animals. HI antibodies were not detected in the CSF of any animal.
Acquisition of Salmonella flora by turtle hatchlings on commercial turtle farms
Authors: Izadjoo Mina J. , Pantoja Carmen O. A. , Siebeling R. J.
Published: May 2010

A commercial turtle pond in South Louisiana was studied to identify the mechanism by which turtle hatchlings acquire Salmonella flora. The visceral organs and mature eggs removed from 31 adult gravid female turtles over the course of two egg-laying seasons and from 37 adult females during one winter dormant period were examined bacteriologically for Salmonella. Pond water, egg nest soil, and hatchlings produced by eggs removed from the oviducts and nest soil were also tested. Eighty-eight turtles hatched from eggs removed from the oviducts of 15 turtles at necropsy did not excrete or harbor systemically Salmonella, nor were these pathogens isolated from ovarian tissue or immature eggs. The findings suggest transovarian transmission of these pathogens does not occur frequently. Turtles hatched from eggs retrieved from soil nests 1 to 2 h after deposition harbor and excrete these organisms. This result coupled with the isolation of these pathogens from the cloaca, colon contents, and bursal fluid from 18 females captured in the act of egg laying supports the cloaca to egg and nest soil to egg mode for salmonellae infection in the resultant hatchling. Salmonella arizonae and Salmonella serogroups B, C2, and E1 were isolated from the cloaca, colon contents, pond water, and nest soil, and were excreted by hatchlings produced from eggs removed from the soil nests. These same serogroups were isolated from the colon contents of 19 of 37 females tested during the dormant period, suggesting the salmonellae persist in the pond environment in the adult throughout the year.
Derivation and molecular characterization of symbiotically deficient mutants of Rhizobium meliloti
Authors: Selvaraj G. , Hooper I. , Shantharam S. , Iyer V. N. , Barran L. , Wheatcroft R. , Watson R. J.
Published: May 2010

A collection of symbiotically defective mutants of Rhizobium meliloti JJ1c10 was derived by Tn5 mutagenesis using the suicide vector pGS9. They include two Nod− and about 250 Fix− mutants. The mutants were found to be heterogenous in acetylene reduction activity and in the morphology and ultrastructure of the nodules which they induced. Over 90% were found to contain bona fide Tn5 insertions in a variety of DNA restriction fragments. When Tn5-carrying DNA segments cloned from 24 of the mutants were introduced into the equivalent location in the genome of the wild-type strain by recombination-mediated replacement, only eight produced a symbiotically defective phenotype similar to that of the original mutant. This result indicated that many of the symbiosis mutations were not directly caused by Tn5 insertion. DNA segments apparently containing mutated fix genes but not containing Tn5 were found in eight mutants by identifying cosmids carrying wild-type DNA which complemented their symbiosis defects. Probing of the DNA of these mutants with their complementing cosmids revealed no detectable physical alteration of the homologous DNA. A segment of DNA including the hsn and nifHDK genes was favoured for these non-Tn5 mutations. Three regions of the genome in which Tn5 caused fix mutations were identified. One of these was the known megaplasmid nod-nif region. The other two regions, designated fix-e5 and fix-h21, were found to be chromosomal. Mutants in one of these chromosomal regions fluoresced more intensely on calcofluor plates than the wild type.
Biosynthesis of trans fatty acids from acetate in the bacterium Pseudomonas atlantica
Authors: Guckert James B. , Ringelberg David B. , White David C.
Published: May 2010

The cis configuration in fatty acids is the only known product of bacterial biosynthetic pathways of monounsaturated membrane fatty acids. The trans configuration is considered "nonphysiologic" or "unnatural." This research shows that in vivo synthesis of trans-monounsaturated membrane fatty acids from acetate occurs in the bacterium Pseudomonas atlantica. The saturated, trans, and cis phospholipid fatty acids (PLFA) of P. atlantica grown in the presence of [14C]acetate were physically separated as the corresponding fatty acid methyl esters (FAME) and the presence of trans FAME was verified by infrared spectroscopy. The FAME isomers were quantified by gas chromatography and 14C incorporation into these isomers was counted. The specific activities of trans and saturated PLFA were found to be equivalent, indicating that P. atlantica has the in vivo biosynthetic capabilities to synthesize trans PLFA from acetate. From these results, a biosynthetic pathway is hypothesized and the suggestion is made that P. atlantica would be a preferred test organism to elucidate this pathway as well as to test the ecological implications of these trans PLFA in terms of starvation survival and the initial biofouling–adhesion process.
Separation of various Frankia strains in the Alnus and Elaeagnus host specificity groups using sugar analysis
Authors: St-Laurent L. , Bousquet J. , Simon L. , Lalonde M.
Published: May 2010

To confirm the role of glycosides in the taxonomy of Frankia, 79 strains initially isolated from Alnus spp., Myrica spp., Comptonia sp., Elaeagnus spp., Shepherdia spp., and Hippophaë sp. host plants were tested for relative sugar content after 2 and 8 weeks of growth. Gas chromatography was used to separate the trimethylsilyl derivatives of sugars present in whole-cell hydrolysates of the Frankia strains; six sugars were quantitatively analyzed including 2-O-methyl-D-mannose, a sugar ubiquitous in the genus Frankia. The separation of the Frankia strains into their appropriate host specificity group (Alnus or Elaeagnus), based only on the sugar content, was achieved using statistical analyses of observations at 2 and 8 weeks. All statistical analyses correlated together and showed a significant separation between both host specificity groups. 2-O-Methyl-D-mannose, the concentration of which varied greatly between the Alnus and Elaeagnus host specificity groups, was the most discriminant sugar. Moreover, it was constant at both ages. From discriminant analysis, the separation of the various Frankia strains tested into their respective host specificity group was more precise at 2 weeks with a classification success of 97%, as compared with 78% at 8 weeks. The Myrica gale isolates that nodulated host plants from both host specificity groups were generally intermediate in their sugar content between the Alnus and Elaeagnus host specificity groups.
Changes in the hydrophobic characteristics of Clostridium perfringens spores and spore coats by heat
Authors: Craven S. E. , Blankenship L. C.
Published: May 2010

The hydrophobic characteristics of Clostridium perfringens NCTC 8679 spores were demonstrated by adherence to toluene in a toluene–aqueous partition system. Spores and spore coat preparations were hydrophobic. Vegetative cells and spores extracted with a dithiothreitol – sodium dodecyl sulfate treatment known to remove spore coats were not hydrophobic. A heat activation treatment (75 °C for 20 min) which promotes more rapid spore germination increased the hydrophobicity of intact spores and decreased that of isolated spore coats. The hydrophobic changes were reversed by washing and stabilized by 0.5% glutaraldehyde. Heat-induced hydrophobic changes were observed in spore coats prepared from spores that were preheated and washed before rupturing in a buffer containing glutaraldehyde. These results suggest the occurrence of a heat-induced change in the spore coat (possibly in the conformation of a macromolecule) which was stable only within the architectural confines of the intact spore.
Survival of human rhinovirus type 14 dried onto nonporous inanimate surfaces: effect of relative humidity and suspending medium
Authors: Sattar Syed A. , Karim Yasmin G. , Springthorpe V. Susan , Johnson-Lussenburg C. M.
Published: May 2010

To study the survival of human rhinovirus 14 on environmental surfaces, each stainless steel disk (1 cm in diameter) was contaminated with 10 μL (about 105 plaque-forming units) of the virus suspended in either 1χ tryptose phosphate broth (TPB), 5 mg/mL of bovine mucin in normal saline, or undiluted human nasal discharge. The inoculum was dried in a laminar flow cabinet for 1 h under ambient conditions. The disks were then placed in a glass chamber (20 ± 1 °C) with the relative humidity at either low (20 ± 5%), medium (50 ± 5%), or high (80 ± 5%) level. At appropriate intervals, the disk to be tested was placed in 1 mL of tryptose phosphate broth and the eluate titrated in A-5 HeLa cells. When the virus was suspended in either tryptose phosphate broth, mucin, or the nasal discharge and subjected to initial drying, there was a 3.0 ± 1.0, 82.0 ± 6.7, and 89.0 ± 3.0% loss in virus infectivity, respectively. The half-life of the TPB-suspended virus was about 14 h at the high relative humidity as compared with < 2 h at the other two relative humidity levels. The half-lives for the mucin-suspended virus at the high, medium, and low relative humidity were 1.42, 0.55, and 0.24 h, respectively; the corresponding values for the nasal discharge suspended virus being 0.17, 0.25, and 0.09 h.
Microstage development for protoplasts of the fungus Entomophaga aulicae
Authors: Nolan Richard A.
Published: May 2010

During morphogenesis the fungus Entomophaga aulicae produces both normal size (designated macrostages) and a smaller size class (designated microstages) of the spindle-shaped, early fusion sphere, and late fusion sphere protoplasts. Two additional stages (which lack macrostage counterparts), the granular microstage and the solid microstage (which can germinate to form a hypha), are also produced. The sizes, developmental sequences, and growth rates of the macro- and micro-stages are compared. The microstages are produced in both highly enriched and minimal growth media and by several isolates and are, therefore, considered normal components of E. aulicae protoplast morphogenesis. Some possible implications of microstage occurrence are mentioned.
Antibiotic resistance and plasmid pattern of enterotoxigenic ST-a strains of Escherichia coli isolated in Puebla, México
Authors: Martínez L. Y. , Arenas M. M. P. , Montes M. Y. R. , Martínez L. J. , Baca B. E.
Published: May 2010

Antibiotic susceptibilities of 22 strains of Escherichia coli isolated from children from 0 to 3 years old at the University Hospital of Puebla were determined. Almost all strains were resistant to ampicillin, tetracycline, streptomycin, and kanamycin. Gel electrophoresis of DNA from 10 clinical strains of E. coli revealed a heterogeneous plasmid population. Plasmid DNA, ranging in molecular mass from 1.8 to 120 megadaltons, was demonstrated in 10 strains. Moreover, the frequency of antibiotic transfer ranged from 1.6/108 to 2/10, and the simultaneous transfer of the gene encoding heat-stable enterotoxin was also determined. Six out of 10 strains tested were able to cotransfer ST-a as demonstrated by the suckling mouse test. It is possible that antibiotic selective pressure may increase the isolation of enterotoxigenic E. coli strains.
Characterization of Azomonas macrocytogenes strains isolated from Alberta soils
Authors: Page William J. , Collinson S. Karen
Published: May 2010

Five strains of Azomonas macrocytogenes were identified from a collection of aerobic nitrogen-fixing organisms obtained from Alberta soils. The cell morphology, colony appearance, and growth conditions of these five isolates and their use of nitrogen and carbon sources were in good agreement with four standard Azomonas macrocytogenes strains. The new strains did not produce N,N,N′,N′-tetramethyl-p-phenylenediamine-dependent cytochrome oxidase, were unable to form true cysts, formed blue–white fluorescent compound(s) under iron-limited conditions, and excreted 3,4-dihydroxybenzoic acid into culture fluids. The detection of this catechol proved to be more reliable and convenient than the observation of the red–violet colour of its ferrated form, which was a variable occurrence in older cultures. Four of the new strains were antagonistic to Agrobacterium tumefaciens and two strains stimulated Erwinia carotovora growth. The new strains also demonstrated nitrogen fixation under molybdate-deficient conditions, which suggested the presence of an alternative molybdate-independent nitrogenase.
Alteration in glyceollin synthesis and antigenic patterns after chemical induction of resistance in soybean to Macrophomina phaseolina
Authors: Chakraborty B. N. , Purkayastha R. P.
Published: May 2010

Sodium azide was found to be most effective of the six metabolic inhibitors tested in reducing charcoal rot disease of soybean (cv. Soymax) caused by Macrophomina phaseolina. Glyceollin production also increased significantly after induction of resistance by sodium azide treatment. Cross-reactive antigens were detected in purified preparations from mycelia of M. phaseolina with antisera of soybean roots by immunodiffusion and immunoelectrophoretic tests. An antigenic dispartity was noticed in the susceptible cultivar (cv. Soymax) after chemical induction of resistance. The changes in antigenic pattern and their involvement in induced resistance of soybean to M. phaseolina are discussed.
An epifluorescent microscopy study of enzymatic hydrolysis of fluorescein diacetate associated with the ectoplasmic net elements of the protist Thraustochytrium striatum
Authors: Coleman Nancy K. , Vestal J. Robie
Published: May 2010

Thraustochytrium striatum, grown in slide culture, was examined for hydrolytic enzymatic activity using epifluorescence microscopy and fluorescin diacetate. Enzyme activity was noted in the thallus, ecoplasmic nets, and the culture medium when cells were present. Various carbon sources were used to determine the optimal nutritional conditions for enzyme production within the nets. In a seawater medium, glucose and pine pollen provided the best enzyme activity in ecotoplasmic nets, followed by glucose, then sucrose, chitin, carboxymethylcellulose, yeast extract, and yeast nitrogen base. It was concluded that the ecotoplasmic nets contained active hydrolytic enzymes which could be either excreted into the surrounding medium or remain attached to the net surface and thus serve to help degrade complex substrata.
Creation of artifactual internal membranes during fixation of Methanobacterium thermoautotrophicum
Authors: Aldrich Henry C. , Beimborn Dieter B. , Schönheit Peter
Published: May 2010

Methanogenic bacteria chemically fixed for electron microscopy contain internal membranes in the form of mesosomes and nucleoid vesicles, and the function of these membranes in methanogenesis and ATP synthesis has been speculated upon. Cells of Methanobacterium thermoautotrophicum fixed in phosphate-buffered 2.5% glutaraldehyde, 0.1% osmium tetroxide, or 0.5% glutaraldehyde – 2.5% formaldehyde always contain internal membranes. Cells freeze-fractured, freeze-substituted, or fixed in cacodylate-buffered 1% osmium tetroxide, 2.5% glutaraldehyde, or simultaneous glutaraldehyde–osmium lack internal membranes. We conclude that internal membranes in this species are artifacts arising during suboptimal fixation conditions.
Biocontrol of seed-borne Alternaria raphani and A. brassicicola
Authors: Vannacci G. , Harman G. E.
Published: May 2010

Forty-two microorganisms were tested as biological control agents against Alternaria raphani and A. brassicicola. Tests were conducted for in vitro antagonistic ability, for ability to control the pathogens on naturally infected seeds germinated on moistened blotters, and in planting mix in growth chamber studies, and for their ability to reduce pod infection. The organisms tested were obtained from cruciferous seeds or were strains already identified as being effective against soil-borne Pythium species. The blotter test indicated that six organisms increased both the number of healthy seedlings and the number of seedlings produced from A. raphani infected radish seeds. An additional seven strains improved either germination or increased the number of healthy seedlings. Twenty-nine organisms increased the number of healthy cabbage seedlings from A. brassicicola infected seeds, but total germination was not modified by any treatment. Experiments in planting mix showed that five antagonists (Chaetomium globosum, two strains of Trichoderma harzianum, T. koningii, and Fusarium sp.) increased the number of healthy plants in both radish samples tested, while four additional antagonists provided a significant increase in only one of the samples tested. The five antagonists that consistently increased numbers of healthy radish seedlings also decreased pod infection by A. raphani. None were as effective as iprodrone, however. Several effective antagonists were found to be mycoparasitic against Alternaria spp. Some strains of Trichoderma previously found to be effective against Pythium spp. were also effective against Alternaria spp., indicating that these strains have a wide host range.
Purification of urease from Ureaplasma urealyticum
Authors: Stemke G. W. , Robertson J. A. , Nhan M.
Published: May 2010

We have purified urease from the Mollicutes, Ureaplasma urealyticum, using high performance liquid chromatography methods and DEAE-Sephadex chromatography. While only small amounts of material could be utilized in these methods, urease was purified at least 180-fold, to yield a major band on SDS–PAGE of 660 00 daltons, a minor band of 64 000 daltons, and several faint bands of lower molecular mass. These results suggest that the 380 000 dalton intact urease is a pentamer or hexamer of these two larger subunits. The highly purified urease from DEAE-Sephadex retained full activity for at least 20 days at 4 °C in sodium phosphate buffer (pH 7.2) with 1% bovine serum albumin. The estimated specific activity of the DEAE peak fractions, 180 IU/μg, is at least 90-fold greater than that of jack bean urease.
Recovery of β-lactamase producing bacteria in pediatric infections
Authors: Brook Itzhak
Published: May 2010

The presence of β-lactamase producing bacteria (βLPB) was investigated in specimens obtained from 1469 children who presented with infections of the skin and soft tissue (648), upper respiratory tract (514), pulmonary sites (137), surgical sites (113), and other (57). Of 4989 bacterial isolates recovered, 910 (18%) were βLPB, 492 (54%) aerobes, and 418 (46%) anaerobes. The βLPB were recovered in 751 (51%) of the children. The most frequently recovered βLPB was Staphylococcus aureus, which was recovered in 356 (47%) patients. Most isolates were recovered from patients with skin and soft-tissue infections (68% of patients), upper respiratory tract infections (49%), and pulmonary infections (35%). Bacteroides fragilis group was isolated in 35% of patients with βLPB, mostly from surgical infections (98% of patients), pulmonary infections (36%), skin and soft-tissue infections (25%), and upper respiratory tract infections (20%). Twenty-five percent of the Bacteroides melaninogenicus group produced β-lactamase. These organisms were recovered in 15% of patients with βLPB. They were recovered in upper respiratory tract infections (38% of patients), pulmonary infections (22%), and skin and soft-tissue infections (7%). Other βLPB were Pseudomonas aeruginosa (8% of total patients with βLPB), Escherichia coli (4%), Bacteroides oralis (3%), Klebsiella pneumoniae (3%), Haemophilus influenzae (2%), Proteus (1%), and Branhamella catarrhalis (1%). The role of βLPB in the failure of penicillin to eradicate many of the infections is discussed.
Growth of Verticillium dahliae Kleb. hyphae and of bacteria along the roots of rape (Brassica napus L.) seedlings
Authors: Olsson Stefan , Bååth Erland , Söderström Bengt
Published: May 2010

Bacterial density and the hyphal density of Verticillium dahliae were determined along the roots of sand-grown rape seedlings. Verticillium dahliae microsclerotia were trapped in nylon nets which were placed in front of the growing root tip. The growing hyphae on the nets were stained with fluorescein diacetate and rhodamine B isothiocyanate. Bacteria on the petri dish lids adjacent to the nets were stained with acridine orange. Both fungal and bacterial densities increased exponentially over a distance of 15–20 mm from the root tip. Further back along the root, the densities of microorganisms stabilized, but in some cases the fluorescein diacetate active hyphal density increased. The hyphal densities stopped increasing before bacterial densities, suggesting an increasing bacterial competition for root exudates as their population grew. The hyphal activity, measured as the proportion of flurescein diacetate to rhodamine B isothioicyanate stained hyphae, increased during the exponential growth phase of the bacteria, then decreased, and finally increased again as the lateral roots appeared.
Murine cytomegalovirus – Pseudomonas synergistic infections: comparison of virulent and attenuated virus
Authors: Kournikakis B. , Babiuk L. A.
Published: May 2010

The synergistic interactions between Pseudomonas aeruginosa and virulent or attenuated murine cytomegalovirus (MCMV) were compared in vivo. Virulent MCMV challenge at a dose of 5 × 105 pfu/mouse intraperitioneally, followed by intranasal superinfection with 5 × 106 cfu/mouse of Pseudomonas aeruginosa after 48 h resulted in greater than 80% mortality, apparently owing to a failure of pulmonary clearance mechanisms. Single infections, or the use of attenuated MCMV in synergistic infections, did not result in significant morbidity or mortality. Infection with virulent MCMV in vivo resulted in the rapid spread of virus to the lung, liver, and spleen, followed later by spread to the salivary glands. Attenuated virus was detected in salivary glands only. Virulent MCMV was more effective in adsorbing to, or infecting, spleen cells in vitro than attenuated virus. Viral neutralization experiments using anti-viral serum, rabbit complement, and anti-mouse IgG confirmed the presence of a nonneutralizing antibody on the surface of the virulent virus. Our results suggest that the presence of the nonneutralizing antibody on virulent MCMV allows the virus to preferentially infect, or adsorb to, Fc+ cells in the peritoneum. These cells may then carry the virus, via the lymphatic circulation, to other areas of the body, resulting in the replication of virus in multiple organs. Virus replication in the lung may, in part, be the cause of the observed suppression of pulmonary clearance.
Dégradation d'un tensio-actif commercial, en présence d'une source complémentaire de carbone, par une communauté bactérienne sélectionnée en milieu marin
Authors: Sigoillot J.-C. , Nguyen M.-H.
Published: May 2010

Bacterial communities that can degrade surfactants have been selected from coastal seawaters contaminated by urban sewages. Only the linear fraction of commercial anionic surfactants was quickly degraded, and a residual fraction representing 10% of the initial concentration always remained. The highest concentrations of surfactant tolerated by these communities depend on the nature of the co-substrate and on the degree of adaptation of the selected bacteria.[Traduit par la revue]
A study of predominant aerobic microflora of black bears (Ursus americanus) and grizzly bears (Ursus arctos) in northwestern Alberta
Authors: Goatcher L. J. , Barrett M. W. , Coleman R. N. , Hawley A. W. L. , Qureshi A. A.
Published: May 2010

Swab specimens were obtained from nasal, rectal, and preputial or vaginal areas of 37 grizzly and 17 black bears, captured during May to June of 1981 to 1983, to determine the types and frequency of predominant aerobic microflora. Bacterial genera most frequently isolated from bears were Escherichia, Citrobacter, Hafnia, Proteus, Staphylococcus, and Streptococcus species, comprising about 65% of the isolates. Erwinia, Xanthomonas, Agrobacterium, Rhizobium, and Gluconobacter/Acetobacter were also isolated but at lower frequencies (< 5%). Comparison of bacterial generic composition using similarity quotient values showed no appreciable differences between grizzly and black bear flora. Also, no outstanding differences in bacterial generic composition were observed among grizzly bear samples; however, differences were noted among black bear samples. Fungal genera most commonly encountered included Cryptococcus, Rhodotorula, Cladosporium, Penicillium, Sporobolomyces, and Candida. In general, the microflora of both bear types were marked by generic diversity and random distribution. The majority of microorganisms isolated from the plant samples in the study area were also found in bear samples. This observation and the presence of certain water and soil bacteria in samples from bears suggest that the predominant microflora of both grizzly and black bears were transient and probably influenced by their foraging habits and surrounding environments.
Biochemical and immunochemical analyses of detergent solubilized antigens from membrane vesicles of Aspergillus fumigatus
Authors: Piechura James E. , Riefel Randall S. , Daft Laureen J.
Published: May 2010

A membrane vesicle fraction isolated from exponentially growing Aspergillus fumigatus strain Ag 507 cultures was obtained by mechanical disruption of intact Aspergillus cells under specific osmotic conditions followed by a pH fractionation technique. Electron micrographs of the membrane vesicles indicated unit membrane structures free from cell wall material. High glucose-6-phosphatase and low lactate dehydrogenase activities verified the relative purity of the membrane vesicle fraction. Allergic broncopulmonary aspergillosis (ABPA) patient and normal human sera were incubated with the membrane vesicle fraction followed by colloidal gold tagged rabbit antiserum to human IgG or IgE. Electron micrographs indicated ABPA patient sera possessed specific IgG and IgE antibodies to membranous components. The detergent octyl-β-D-glucopyranoside was used to extract membrane vesicle components (MC). The enzyme profile of MC compared with cell sap components (CS) showed differences in types of enzymes. Two-dimensional polyacrylamide gel electrophoretic analyses of MC and CS detected components shared as well as unique to each fraction. In crossed immunoelectrophoresis using both rabbit antisera raised to MC and ABPA patient sera, 5 peaks were detected, while analysis of CS using rabbit antisera raised to CS produced 20 major peaks. Immunoelectrophoresis and double immunodiffusion data supported the crossed immunoelectrophoretic data: MC differed from CS. Enzyme-linked immunosorbent assay indicated high specific IgG and IgE antibody levels to MC in ABPA patient sera. Crossed immuno-affinoelectrophoresis with concanavalin A partially characterized the MC, which consist of components which have glycoprotein elements (i.e., containing α-D-glucose or α-D-mannose).
Conversion of viridin to viridiol by viridin-producing fungi
Authors: Jones Richard W. , Hancock Joseph G.
Published: May 2010

The fungistatic compound viridin, produced by the fungus Gliocladium virens, was found to be irreversibly reduced to the phytotoxin viridiol in liquid culture. Conversion occurred only in the presence of viridin-producing fungi and was subsequent to viridin production. Radiolabelled viridin was rapidly taken up by the mycelium of G. virens and reduced to radiolabelled viridiol, while labelled viridiol was not taken up to any significant extent by the mycelium. Reduction of viridin to viridiol was independent of culture pH, carbon source, and nitrogen source or quantity. A simple production system consisting of peat moss amended with dextrose and calcium nitrate and inoculated with G. virens supported production of 86 μg viridiol/g peat. This production system, when applied to soil, may have value as a herbicide.
Nuclear behaviour accompanying ascus formation in Debaryomyces polymorphus
Authors: Forrest Sharon I. , Robinow Carl F. , Lachance Marc-André
Published: May 2010

Nuclear behaviour in growing, dividing, and ascospore-forming cells of a strain of Debaryomyces polymorphus, a member of the "Torulaspora group" of yeasts, has been studied by light microscopy of fixed Giemsa-stained preparations. Many of the images seen were compatible with the suggestion, advanced by certain earlier students, that meiosis in this type of yeast is preceded by a process of self-diploidization involving the nucleus of a bud that, despite its small size, is already separated from the parent cell by a cross wall. Diploidization, in this view, is achieved by the return of the bud nucleus to the parent cell via a channel in the cross wall. The bud nucleus next fuses with the nucleus of the parent cell. Self-diploidization in D. polymorphus is thus achieved in the guise of heterogamous conjugation. This in turn is followed by meiosis. A lesser number of cell associations suggestive of isogamous conjugation has been encountered also.
Analysis of a hybrid between Kluyveromyces marxianus and Kluyveromyces thermotolerans by physiological profile comparison, isoenzyme electrophoresis, DNA reassociation, and restriction mapping of ribosomal DNA
Authors: Vaughan-Martini Ann , Sidenberg Deborah Gayle , Lachance Marc-André
Published: May 2010

A hybrid yeast strain (LAC/MAL), obtained by Johannsen and van der Walt (1978. Arch. Microbiol. 118:45–48) by growing together strains of Kluyveromyces marxianus (LAC/mal) and Kluyveromyces thermotolerans (lac/MAL), was studied. The nutritional profiles of the hybrid and of some segregants derived from the hybrid indicated that they were more similar to K. marxianus than to K. thermotolerans. This was confirmed by the electrophoretic analysis of isoenzymes, by DNA/DNA reassociation studies, and by restriction endonuclease mapping of ribosomal DNA cistrons. These analyses further indicated that the parent strain identified as K. thermotolerans was atypical of that species. The accumulated evidence ruled out the possibility that the hybrid strain was the result of Mendelian recombination but suggested that some form of transformation might have taken place.
Identification of the A and M antigens of Brucella as the O-polysaccharides of smooth lipopolysaccharides
Authors: Cherwonogrodzky John W. , Perry Malcolm B. , Bundle David R.
Published: May 2010

Rabbit antisera, cross-absorbed serotype-specific for the Brucella A and M antigens, precipitated respectively the smooth lipopolysaccharides from B. abortus 1119-3 and B. melitensis 16M. The anitgenic A and M activity of these lipopolysaccharides was shown to reside within the O-chain region of the smooth lipopolysaccharides by inhibition experiments. Homologous O-polysaccharides showed the highest inhibitory activity in ELISA, although both the A and M antigens were active as heterologous inhibitors, showing that the antigenic determinants of the classical A and M antigens are therefore within the respective O-polysaccharide structures. Their cross-serological activity may be explained in terms of the distinct but related chemical structures of these polysaccharides.
Binding of the Bacillus sphaericus mosquito larvicidal toxin to cultured insect cells
Authors: Davidson Elizabeth W. , Shellabarger Constance , Meyer Marian , Bieber Allan L.
Published: May 2010

Using both fluorescent labelled toxin and antibody – secondary antibody techniques, the Bacillus sphaericus toxin was found to bind strongly to susceptible Culex quinquefasciatus cells, but far less strongly to cells of insensitive insects. An insensitive clone of the C. quinquefasciatus cell line was discovered which bound toxin efficiently. The toxin was bound in the cold to sensitive cells and these cells could be rescued from cytotoxicity for ca. 15 min after warming, by which time toxin appeared to be internalized. Binding was saturable. This toxin is apparently internalized by receptor-mediated endocytosis, probably involving a glycoprotein receptor containing N-acetyl-D-glucosamine. Evidence for toxin binding to lipids was not found. Antibody appeared to detect internalized toxin, and high concentrations of sugars inhibited cytotoxicity; these results along with evidence from a recent ultrastructural study suggest that this toxin may form pores in the cell membrane.
Intra- and inter-specific competition in Rhizobium fredii and Bradyrhizobium japonicum as indigenous and introduced organisms
Authors: Dowdle Stephen F. , Bohlool B. Ben
Published: May 2010

We studied the competition between Bradyrhizobium japonicum and Rhizobium fredii isolates for nodulation of soybean (Glycine max L. Merrill) cultivars Williams and Ai Jiao Zao grown in three different soils in pots. Two of the soils were from People's Republic of China, one from a soybean field in Honghu with no history of Rhizobium inoculation, and one from a rice field in Wuhan with no history of soybean cultivation. The Honghu soil contained B. japonicum and R. fredii (log total number g−1 = 5.82 ± 0.58); whereas the Wuhan soil only contained B. japonicum (log total number g−1 = 2.80 ± 0.52). Inoculation did not result in a significant increase in nodule number on plants in either soil. Uninoculated plants of both cultivars harbored only R. fredii in the Honghu soil and only B. japonicum in the Wuhan soil. Even when B. japonicum were inoculated into the Honghu soil, R. fredii occupied the majority of the nodules on both cultivars. In the Wuhan soil, B. japonicum serogroups USDA110 and USDA136b (= CB1809) occupied the majority of the nodules except when an isolate of R. fredii from the soybean soil was added in high numbers. In a Hawaiian soil devoid of B. japanicum or R. fredii, when soybeans were inoculated with isolates of both species, most of the nodules were formed by B. japonicum. The R. fredii isolate could form up to 20% of nodules in this soil, but only on the Ai Jia Zao cultivar. In the Wuhan but not the Hawaiian soil, peat pelleting of seeds with equal numbers of two B. japonicum and one R. fredii isolates increased nodule occupancy by B. japonicum USDA136b serogroup significantly as compared with when the same isolates were inoculated into the soil. The results reported here highlight the critical importance of being indigenous to the competitive success of B. japonicum and R. fredii in nodulation of their soybean host.
Pronuclear migration, swelling, and fusion during sexual development in Dictyostelium discoideum
Authors: McConachie David R. , O'Day Danton H.
Published: May 2010

In mixed mating type cultures (strains NC4 × V12) of Dictyostelium discoideum, gametes fuse to produce binucleate cells which differentiate into zygote giant cells. As pronuclei move together their volumes increase dramatically. Measurements of pronuclear volumes revealed that there is a direct, linear, and statistically significant relationship between pronuclear size and proximity. Juxtaposition of the swollen pronuclei is followed by their fusion. Ultrastructural studies indicate that pronuclear fusion involves intact pronuclear envelopes.
Bacteria and actinomycetes associated with pot cultures of vesicular–arbuscular mycorrhizas
Authors: Secilia Jean , Bagyaraj D. J.
Published: May 2010

The bacteria and actinomycetes associated with pot cultures of the vesicular–arbuscular (VA) mycorrhizal fungi Glomus fasciculatum, Gigaspora margarita, Acaulospora laevis, Sclerocystis dussii, and of a control without VA mycorrhizal fungus were studied. Total bacterial populations and numbers of nitrogen fixers were significantly higher in the pot cultures of G. fasciculatum, G. margarita, and S. dussii. There were more gram-negative bacteria in these three pot cultures. Spore formers decreased and urea hydrolysers increased in all four pot cultures. The pot cultures of A. laevis harboured fewer bacteria compared with the control. The occurrence of amino acid requiring bacteria increased in all the pot cultures, except that of A. laevis. Pot cultures of G. fasciculatum and A. laevis had significantly more actinomycetes than the control. Streptomyces, series Rectus flexibilis, was selectively stimulated. These two pot cultures also had more actinomycetes antagonistic to the pathogens Fusarium solani and Pseudomonas solanacearum than the control. Glomus margarita pot cultures harboured more actinomycetes antagonistic to the phytopathogenic bacterium Xanthomonas campestris pv. vignicola.
The fate of field-inoculated Azospirillum brasilense Cd in wheat rhizosphere during the growing season
Authors: Bashan Yoav , Levanony Hanna , Ziv-Vecht Orit
Published: May 2010

Following inoculation of wheat grown under field conditions with Azospirillum brasilense Cd, the bacterial population in the plants rhizosphere during the winter growth season was monitored. Seven field experiments were conducted during 3 years, in five soil types, and the bacteria were counted using two different methods of enumeration. Azospirillum brasilense Cd were detected in the wheat fields up to 105 days after inoculation at a level of 104 to 5 × 105 cells/g fresh weight roots, with a very small variation between colonized plants, regardless of the inoculation method. Only a small negligible decrease in the bacterial population occurred during the coldest period of the growing season. Later, the population increased again to the initial level and remained constant. Although inoculated twice, a part of the plant population had not been colonized by A. brasilense Cd. We propose that A. brasilense Cd colonized, although in relatively small numbers, the root system of wheat during the winter season, under suboptimal temperatures for this bacterial species.
Individual reaction requirements of two enzyme activities, isolated from Aspergillus parasiticus, which together catalyze conversion of sterigmatocystin to aflatoxin B1
Authors: Cleveland Thomas E. , Bhatnagar Deepak
Published: May 2010

Individual reaction requirements were determined for each of two enzyme activities present in Aspergillus parasiticus mycelia which together catalyze conversion of sterigmatocystin (ST) to aflatoxin B1 (AFB1). A postmicrosomal activity (PMA) catalyzed conversion of ST to O-methylsterigmatocystin (OMST) and a microsomal activity (MA) catalyzed conversion of OMST to AFB1. PMA was stimulated two- to three-fold in the presence of S-adenosylmethionine. Addition of NADPH promoted the maximum MA; this activity was not detected when FAD, FMN, NAD, or NADH were utilized individually as cofactors in reaction mixtures. A substantial amount (62%) of MA was lost during isolation of the microsomal fraction, but the activity was completely restored by reconstitution with a heat-treated (100 °C) postmicrosomal fraction. The reaction catalyzed by MA was optimum at pH 7.0 and at 17–23 °C, whereas the PMA reaction was optimum at pH 8.0–8.5 and at 35–40 °C. Apparent Km values of approximately 2.6 × 10−6 M (for ST) and 6.6 × 10−7 M (for OMST) were determined for PMA and MA, respectively.
Lipid profiles of conidia of Aspergillus niger and a fatty acid auxotroph
Authors: Chattopadhyay Panchanon , Banerjee Santu Kumar , Sen Kalyani , Chakrabarti Parul
Published: May 2010

Conidial lipids of the wild-type (V35) Aspergillus niger and its unsaturated fatty acid auxotroph (UFA2) were compared. The wild type contained lower levels (7.6%) of phospholipids and higher levels (28.4%) of glycolipids than the mutant (16.5 and 22.2%, respectively). Oleic (33.4%), linoleic (22.5%), palmitic (12.8%), stearic (7.4%), and linolenic (6.2%) were the main fatty acids of the wild type (V35). The mutant grew only in the presence of unsaturated fatty acid having at least one Δ9cis double bond, and its conidial fatty acid profile was influenced by the exogenous acid. Analyses of the fatty acids of UFA2 grown in the presence of different fatty acid supplements support the original view that the mutant is defective in Δ9-desaturase activity.
Chloroquine inhibits cell fusion during sexual development in Dictyostelium discoideum
Authors: Rivera Jiji , O'Day Danton H.
Published: May 2010

Chloroquine inhibits sexual cell fusion and macrocyst formation in heterothallic Dictyostelium discoideum in a dose-dependent manner. As judged by cell morphology, the effect of chloroquine is not due to nonspecific toxicity, and normal macrocyst development ensues upon the removal of the drug. The mode of action of chloroquine on both receptor recycling and protease activity is discussed in terms of current knowledge of sexual cell fusion in D. discoideum.
The specificity of growth inhibition of methanogenic bacteria by bromoethanesulfonate
Authors: Sparling Richard , Daniels Lacy
Published: May 2010

The growth of a wide variety of eubacteria, three nonmethanogenic archaebacteria, and a yeast was not significantly inhibited by 25 mM bromoethanesulfonate, whereas three methanogenic bacteria were completely inhibited by this compound. We conclude that bromoethanesulfonate is a specific and effective inhibitor of methanogenic bacteria, even when used at this high concentration.
Amikacin disrupts the cell envelope of Pseudomonas aeruginosa ATCC 9027
Authors: Walker S. G. , Beveridge T. J.
Published: May 2010

Amikacin, an aminoglycoside known to inhibit protein synthesis, was found to perturb the outer membrane of a sensitive Pseudomonas aeruginosa strain (ATCC 9027). This perturbation was monitored using electron microscopy and biochemical analyses. Following exposure to 20 μg amikacin/mL for 15 min, the outer membrane of exponentially growing cells lost 15% of its protein, 18% of its lipopolysaccharide, and 18% of its phosphate. Sodium dodecyl sulphate – polyacrylamide gel electrophoresis showed that the whole spectrum of outer membrane protein and lipopolysaccharide was affected. Similarly, atomic absorption spectrophotometry revealed that magnesium and calcium were also lost. When cells were treated with amikacin, electron microscopy of negative stains showed a substantial increase in outer membrane blebbing. Freeze fractures revealed changes in membrane fracture pattern and particle distribution, and thin sections revealed a sequential disruption of the cell envelope beginning at the outer membrane and ending at the plasma membrane. This study supports the proposal that aminoglycoside antibiotics cross the outer membrane of Pseudomonas aeruginosa by displacing metal cations necessary to stabilize the organic constituents of the membrane. Their removal results in loss of the outer membrane and the formation of transient small holes which permit the antibiotic access to the cytoplasmic membrane where it is transported into the cytoplasm.
Non-encapsulated mutants of Azospirillum brasilense and Azospirillum lipoferum
Authors: Bastarrachea Fernando , Zamudio Marcela , Rivas Rubi
Published: May 2010

A procedure is described for the isolation of mutants of Azospirillum brasilense strains Sp7 (ATCC 29145) and Sp245 and Azospirillum lipoferum Br1702, which are unable to differentiate from vegetative vibrioids into encapsulated C forms. It is based on the characteristic of mutants, designated Enc−, to develop into white colonies in a background of wild-type red colonies (Enc+) on the surface of Congo Red plates. This behavior was ascribed to an inability of Enc− mutants to synthesize one or more as yet unidentified polysaccharides. The frequency of mutation from Enc+ to Enc− was a function of the particular strain and of the culture conditions employed. Enc− mutants from A. brasilense and A. lipoferum were at least as efficient as wild-type ancestors in adhering to and causing deformations of root hairs of germinated wheat seedlings.
In vitro stabilization of 6-methylsalicylic acid synthetase from Penicillium urticae
Authors: Lam Kin S. , Neway Justin O. , Gaucher G. Maurice
Published: May 2010

In continuing studies of patulin biosynthesis, the first enzyme of the pathway, 6-methylsalicylic acid synthetase, was found to be far more labile than were the later enzymes of the pathway. Attempts were made to stabilize 6-methylsalicylic acid synthetase in vitro. The combined addition of the cofactor NADPH, the substrates acetyl-CoA and malonyl-CoA, the reducing agent dithiothreitol, and the proteinase inhibitor phenylmethylsulfonyl fluoride to cell-free extracts was found to prolong the half-life of the enzyme as much as 12-fold. This suggested that proteolysis and the conformational integrity of the enzyme may play an important role in controlling the duration of antibiotic biosynthesis in vivo. This was in agreement with the finding that the intracellular proteinase content of antibiotic-producing cells of Penicillium urticae rapidly increased just before the loss of 6-methylsalicylic acid synthetase content. These in vitro stabilization studies have provided some insight into the metabolic conditions that may stabilize these enzymes in vivo, and into possible ways of extending the life of these catalysts.