bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature-dependent structural properties of a solid urea inclusion compound containing chiral guest molecules: 2-bromotetradecane/urea
Authors: Yeo Lily , Harris Kenneth DM
Published: April 2011

Periodic structural properties of the 2-bromotetradecane/urea inclusion compound have been investigated as a function of temperature. Differential scanning calorimetry between 298 and 98 K identified three well-defined regimes, denoted the high-, intermediate-, and low-temperature phases. The structural properties of each phase (at 293, 207, and 142 K, respectively) have been investigated by single crystal X-ray diffraction. In the high-temperature phase, the inclusion compound has the hexagonal urea tunnel structure (P6122) characteristic of the conventional urea inclusion compounds, with substantial orientational disorder of the guest molecules. In the intermediate-temperature phase, the symmetry is lowered to orthorhombic (C2221), although the host structure remains close to the hexagonal tunnel structure of the high-temperature phase and there is no clear evidence for increased orientational ordering of the guest molecules. In the low-temperature phase, the urea tunnel structure is monoclinic (P21), and is based on a 2 × 2 × 1 supercell of the hexagonal cell of the high-temperature structure. There are four independent types of tunnel, three of which are strongly distorted from hexagonal geometry. Within these distorted tunnels, there is a comparatively narrow distribution of guest molecule orientations, which correlate well with the observed distortions of the tunnels. The 2-bromotetradecane/urea inclusion compound highlights several issues of wider relevance concerning the structural properties of solid inclusion compounds.Key words: urea inclusion compounds, X-ray diffraction, phase transitions, chiral recognition, incommensurate solid, 2-bromotetradecane/urea.
Assisted hydrolysis of cis-2-(3-phenylthioureido)cyclo pentane-carbonitrile in alkaline solution. Solvent dependent switch from hydrolysis to rearrangement of the iminothiooxopyrimidine intermediate
Authors: Atay Ergun , Blagoeva Iva B , Chubb Francis L , Edward John T , Pojarlieff Ivan G , Toteva Maria M
Published: April 2011

The cis and trans isomers of 2-(3-phenylthioureido)cyclopentanecarbonitrile, 1, and the respective carboxamides, 3, and acids, 4, have been prepared. Acid cyclization of both nitriles, faster with the cis isomer, gave the more stable cis-2-thiooxo-cyclopenta[d]pyrimidin-4-one, 7. In base cis-1 formed the cis 4-imino-2-thiooxopyrimidine 2 which in aqueous alkali broke down via 3 to the acid 4; while in the presence of 66% acetonitrile 2 rearranged to the 4-phenyliminopyrimidine 5 to give as final product the thioureido acid 6 carrying no phenyl group. The 1H NMR data for imino and phenylimino derivatives 2 and 5 showed strong bias for conformation A with 1-N pseudoaxial in the cyclopentane ring. Spectra of the E andZ isomers of the iminopyrimidine 2 under slow exchange could be recorded in DMSO-d6. The phenylimino tautomer of 5 is observed in CD3OD and in CDCl3 with the E and Z isomers in a 1:1 ratio. In DMSO-d6 the phenylamino tautomer 5a is also detected. The first process in aqueous KOH, the conversion of nitrile cis-1 into the imino intermediate 2, reaches an equilibrium which shifts towards the nitrile at higher alkalinities because of ionization of the phenylthioureido group (Ke = [2]/[1] = 2.43 and pKAH = 12.74). The cyclization of 1 to 2 is first order in [OH-] while the slower breakdown of 2 is pH independent. The latter is 104 times faster than the hydrolysis of acetonitrile evidencing substantial anchimeric assistance. The change in the reaction route towards the rearranged phenyliminopyrimidine 5 upon addition of acetonitrile can be caused by the lower dielectric constant favouring the elimination step leading to the intermediate isothiocyanate, and by increased activity of OH- accelerating the (presumably) second order elimination step as opposed to the pH-independent hydrolysis of the imino derivative 2. Key words: anchimeric assistance, phenylthioureido nitriles, iminothiooxopyrimidine tautomers, alkaline hydrolysis, solvent effects.
Aqueous nonelectrolyte solutions. Part XVI. Formula of deuterium sulfide D-hydrate and its dissociation thermodynamic functions
Authors: Clarke Colin W , Glew David N
Published: April 2011

A method has been devised to approximate both the hydrate formula number n and the standard thermodynamic functions for hydrate dissociation from the temperature change of the hydrate former fugacity along a univariant three-phase (hl1g) equilibrium line. Thermodynamic equations are derived, their validity discussed, and an iterative method for their solution is described. The univariant (hl1g) equilibrium dissociation of deuterium sulfide D-hydrate (D2S·nD2O phase h) into gaseous deuterium sulfide (g) and liquid deuterium oxide (l1) has been treated to give approximate formulae and dissociation constants at 58 temperatures from 2.798 to 30.666°C. Dissociation equilibrium constants Kp(h–> l1g) have been represented as a function of temperature by a four-parameter equation which yields both values and standard errors (i) for ΔHot(h–> l1g) and ΔCpot(h–> l1g) the standard enthalpy and heat capacity changes for D-hydrate dissociation and (ii) for n = r the approximate formula number of the D-hydrate at each experimental temperature. The formula D2S·6.115D2O with standard error 0.018D2O is found for deuterium sulfide D-hydrate at lower quadruple point Q(hs1l1g) 3.392°C; an approximate formula D2S·5.840D2O with SE 0.019D2O is found at upper quadruple point Q(hs1l2g) 30.770°C.

Key words: clathrate D-hydrate of deuterium sulfide, deuterium sulfide D-hyfrate, formula of deuterium sulfide D-hydrate, thermodynamics of clathrate hydrate dissociation, dissociation equilibrium constant of deuterium sulfide D-hydrate, standard enthalpy, and heat capacity changes for dissociation of deuterium sulfide D-hydrate.
Synthesis and X-ray structures of amidinate, oxoamidate, and thioamidate complexes of boron
Authors: Blais Pierre , Chivers Tristram , Downard Andrew , Parvez Masood
Published: April 2011

The reactions of PhBCl2 with Li[CE(NtBu)(nBu)] or Li[CS(NtBu)(NHtBu)] (1:1 molar ratio) in toluene at 23°C produced the heterocycles Ph(Cl)B(μ-NtBu)(μ-E)C(nBu) (1a, E = NtBu; 1b, E = O; 1c, E = S) or Ph(Cl)B(μ-NtBu)(μ-S)C(NHtBu) (2), which were characterized by 1H, 11B and 13C NMR and by mass spectra. X-ray structural determinations revealed that 1a, 1c and 2 contain four-membered rings. In 2 the thioamidate ligand adopts an N,S bonding mode. Crystal data: 1a, monoclinic, space group P21, a = 8.816(3), b = 11.311(2), c = 10.168(3) Å, β = 98.86(3)°, V = 1001.7(5) Å3, Z = 2, R = 0.042, and Rw = 0.020; 1c, monoclinic, space group P21/n, a = 7.617(2), b = 11.200(1), c = 19.568(2), β = 90.74(2)°, V = 1669.1(5) Å3, Z = 4, R = 0.046, and Rw = 0.059; 2, monoclinic, space group P21/a, a = 11.357(2), b = 12.289(2), c = 12.620(3) Å, β = 95.43(2)°, V = 1753.4(5) Å3, Z = 4, R = 0.043, and Rw = 0.027. Key words: boron, amidinate, oxoamidate, thioamidate, X-ray structures.
On chirality measures and chirality properties
Authors: Weinberg Noham , Mislow Kurt
Published: April 2011

It is shown that chiral zeroes are integral to all pseudoscalar functions, and that these functions, and thus the chirality properties that are described by them, are therefore normally unsuitable as chirality measures. The multidimensional nature of chirality properties is explored. Chirality measures for nonrigid objects and stochastic systems are discussed. It is shown that if the chirality of a nonrigid object is described as a time average of the chirality measures of its instant configurations, this time average is nonzero not only for chiral but also for achiral molecules. This paradox can be resolved if chirality measures are properly applied to nonrigid objects.Key words: chirality, chiral zeroes, chirality measures, chirality properties.
Investigations on nonradiative transitions in different environments using excited (or ground state) 1,2,3,4-tetrahydroquinoline (THQ) as donor and ground state (or excited) 9-fluorenone (9FL) or 2-nitro-9-fluorenone (2N9FL) as acceptors
Authors: De Avijit K , Ganguly Tapan
Published: April 2011

By using steady state and time resolved spectroscopic techniques, investigations were made on the nature and mechanisms of different nonradiative processes involved within the excited donor (or acceptor) and ground state acceptor (or donor) in nonpolar n-heptane (NH), polar protic ethanol (EtOH), and polar aprotic acetonitrile (ACN) solvents at the ambient temperature as well as in EtOH rigid glassy matrix at 77 K. The bicyclic molecule 1,2,3,4-tetrahydroquinoline (THQ) was used as a donor (D) in the present investigation whereas 9-fluorenone (9FL) and 2-nitro-9-fluorenone (2N9FL) were chosen as electron acceptors (A). When the donor chromophore was excited in presence of an acceptor, highly exothermic electron transfer (ET) reactions seemed to occur from observed large negative driving energy (deltaG0) values, measured by electrochemical techniques, Förster's type energy transfer, static quenching, etc. An attempt was made to estimate separately the contributions of static and dynamic quenching modes in the overall quenching mechanism of donor fluorescence by using a model of modified Stern-Volmer (SV) relation. From this relation it seemingly indicated that the major contribution in quenching originated from the static mode. When excited acceptors react with the ground state donor THQ it is primarily ET reactions that seem to occur. Observations of the transient absorption spectra, by laser flash photolysis techniques, of contact ion-pairs of the present D-A systems along with the triplet absorption spectra of the monomeric acceptor (9FL and 2N9Fl) corroborate our views regarding the occurrence of photoinduced ET reactions within the present reacting systems. At 77 K the combined effect of Förster type energy transfer and static quenching seems to be responsible for observed lowering of donor fluorescence emission intensity in presence of acceptors (9FL or 2N9FL). However, the phosphorescence lifetime measurements reveal that the triplet donor might be involved in photoinduced ET reaction with the unexcited acceptor in rigid glassy matrix at 77 K and this possibly causes the reduction in the phosphorescence band intensity of the donor THQ in presence of the latter one. Key words: electron transfer, static quenching, fluorescence quenching, phosphorescence, energy transfer.
Characterization of phosphorus chemical shielding tensors in a phosphole tetramer: a combined experimental and theoretical study
Authors: Gee Myrlene , Wasylishen Roderick E , Eichele Klaus , Wu Gang , Cameron T Stanley , Mathey F , Laporte F
Published: April 2011

Phosphorus-31 1D NMR spectra of a stationary powder sample of a phosphole tetramer containing two phosphorus spin pairs have been obtained at 4.7 T and 9.4 T. In order to separate 31P-31P spin-spin coupling from anisotropic chemical shielding, 2D spin-echo NMR spectra have been acquired. Phosphorus-31 CPMAS NMR experiments indicate that the two spin pairs of the tetramer are equivalent and each may be treated as an isolated spin pair. Within a given spin pair, the difference between the isotropic chemical shifts of two directly bonded phosphorus nuclei is 1.7 ppm. As well, they are spin-spin coupled by both the indirect and direct interactions, 1J(31P, 31P) = -362 Hz and RDD = 1.80 kHz, respectively. The principal components and relative orientation of the two phosphorus chemical shielding tensors have been determined using the dipolar-chemical shift technique; however, since the dipolar tensor is axially symmetric, ambiguities in the chemical shielding tensor orientation relative to the molecular framework result. Using ab initio calculations and simulations of the 2D spin-echo spectra, many of these ambiguities have been resolved. The spans and skews of the phosphorus shielding tensors for all four three-coordinate phosphorus nuclei are the same within experimental error, 115 ppm and 0.70, respectively. Combined experimental and theoretical results indicate that the phosphorus shielding tensor orientations are dictated by the local environment. For both shielding tensors, the most shielded component, δ33, is approximately 78° from the P-P bond and in the phosphole ring plane. The relative orientation of the δ33 components is described by a dihedral angle of 82°, similar to the dihedral angle of approximately 76° defining the twist of the phosphole rings about the bridging P-P bond.Key words: solid-state 31P NMR, phosphorus chemical shielding tensors, phosphole tetramer, 31P31P spin pairs, ab initio calculations.
Solubility of the pesticide diuron in organic nonelectrolyte solvents. Comparison of observed vs. predicted values based upon Mobile Order theory
Authors: De Fina Karina M , Sharp Tina L , Spurgin Michael A , Chuca Ivette , Acree, Jr. William E , Green Caroline E , Abraham Michael H
Published: April 2011

Experimental solubilities are reported at 25.0°C for diuron (also called 3-(3,4-dichlorophenyl)-1,1-dimethyl urea) dissolved in 49 different organic nonelectrolyte solvents containing ether-, chloro-, hydroxy-, ester-, methyl-, and tert-butyl-functional groups. Results of these measurements are used to test the applications and limitations of expressions derived from Mobile Order theory. For the 28 nonalcoholic solvents for which predictions could be made computations show that Mobile Order theory does provide fairly reasonable estimates of the saturation mole fraction solubilities. Average absolute deviation between predicted and observed values is 60.1%. Diuron solubilities in the alcohol solvents are used to calculate stability constants for presumed solute-solvent hydrogen bonds that are believed to occur in solution.Key words: pesticide, diuron solubilities, organic nonelectrolyte solvents, solubility predictions.
Efficient synthesis of optically active 2-amino-2'-diphenylphosphino-1,1'-binaphthyl and its derivatives
Authors: Sumi Kenzo , Ikariya Takao , Noyori Ryoji
Published: April 2011

Optically active 2-amino-2'-diphenylphosphino-1,1'-binaphthyls having various functional groups, such as amino, alkoxycarbonylamino, acylamino, mono- and dialkylamino, and sulfonylamino at C2 position were prepared. The key intermediate of the above aminophosphines was 2-carbamoyl-2'-diphenylphosphinyl-1,1'-binaphthyl synthesized from optically active 2-cyano-2'-diphenylphosphinyl-1,1'-binaphthyl. The transformation of the carbamoyl group to an amino group was effected by the Hofmann reaction.Key words: aminophosphine ligand, Hofmann reaction, optically active phosphine ligand.
Characterization of a gene locus from Erwinia amylovora with regulatory functions in exopolysaccharide synthesis of Erwinia spp.
Authors: Aldridge Phillip , Bernhard Frank , Bugert Peter , Coplin David L , Geider Klaus
Published: April 2011

In a genomic library of Erwinia amylovora, a locus has been identified that can suppress an Erwinia stewartii rcsA mutant. In addition, the locus induced a mucoid sticky phenotype of colonies in a wild-type strain of Erwinia stewartii and increased exopolysaccharide synthesis in several species of bacteria belonging to the genus Erwinia. An open reading frame was identified at this locus encoding a 225 amino acid protein that contained a helix-turn-helix motif typical of transcriptional regulators. The corresponding gene was subsequently named rcsV (regulator of capsular synthesis affecting viscosity). A mutant of rcsV in wild-type Erwinia amylovora had no detectable phenotype and produced typical levels of amylovoran under laboratory conditions. The rcsV gene on a high copy number plasmid under the control of its own promoter did not alter amylovoran production, in contrast to in-frame fusions of the structural gene in expression vectors. Since even the lac promoter was inert in the expression of rcsV, a DNA-binding protein could inhibit transcription of the gene in Erwinia amylovora. On the other hand, an Erwinia amylovora rcsA mutant was suppressed by rcsV when its promoter was replaced and the structural gene fused in-frame with lacZ' or malE. Northern blots, with total RNA from Erwinia amylovora, or promoter analysis using the GUS reporter gene did not show expression of rcsV in Erwinia amylovora, although primer extension analysis did. RcsV could be a component involved in the regulation of amylovoran synthesis, and gene expression may require an unknown external signal during the life cycle or pathogenesis of Erwinia amylovora. Key words: amylovoran, fire blight, rcsA-like activator, fusion protein.
Synergistic anti-Newcastle disease virus activity of pokeweed antiviral protein, ribavirin, and guanidine
Authors: Weaver Eric , Aron Gary M
Published: April 2011

Pokeweed antiviral protein (PAP), in combination with either guanidine or ribavirin, exhibited both synergy and antagonism toward the replication of Newcastle disease virus. Low, medium, and high effective concentrations of both PAP and guanidine were synergistic when used in combination. High effective concentrations of ribavirin in combination with PAP were antagonistic, whereas low and medium effective concentrations were synergistic. Key words: pokeweed antiviral protein, Newcastle disease virus, ribavirin, guanidine, synergy.
Gene sequences of the pcpB gene of pentachlorophenol-degrading Sphingomonas chlorophenolica found in nondegrading bacteria
Authors: Saboo Vandana M , Gealt Michael A
Published: April 2011

Bacteria isolated from a pentachlorophenol (PCP) contaminated site grew in the presence of 50 µg PCP/mL but were not able to degrade it in either liquid medium or the presence of 1% sterile potting soil as a solid support. Probes developed using the gene sequence of PCP-4-monooxygenase (pcpB) from Sphingomonas chlorophenolica sp.nov hybridized to two separate isolates. Identification based on fatty acid methyl ester profiles (Sherlock), substrate utilization (BIOLOG), and 16S rRNA showed that the two strains were different from each other and from Sphingomonas chlorophenolica. Sequences from these isolates, amplified by polymerase chain reaction, confirmed the homology with pcpB. The presence of pcpB sequences in these nondegraders indicated that growth and hybridization data alone were insufficient for predicting degradation capability. Key words: pentachlorophenol, Sphingomonas chlorophenolica, pcpB gene, pentachlorophenol-4-monooxygenase.
Susceptibility of three strains of conventional adult mice to intestinal colonization by an isolate of Escherichia coli O157:H7
Authors: Conlan J Wayne , Perry Malcolm B
Published: April 2011

Three mouse strains were assessed for their susceptibility to intestinal colonization by a strain of the enteric bacterial pathogen Escherichia coli O157:H7. Following intragastric inoculation of E. coli O157:H7, the intestines of young adult female CD1, BALB/c, and C57BL/6 mice became colonized, as evidenced by faecal shedding of the pathogen for periods of up to 5 weeks. None of the three mouse strains examined developed overt disease in response to colonization by the organism. Following clearance of the primary inoculum, BALB/c mice, but not CD1 or C57BL/6 mice, appeared to acquire enhanced resistance to recolonization by E. coli O157:H7, as evidenced by a decreased faecal shedding period. This enhanced resistance correlated with the presence and persistence of immunoglobulin A, but not immunoglobulin G, in the serum and faeces directed against the O157 antigen. The implications of these findings to vaccine development against E. coli O157:H7 are discussed.Key words: E. coli O157:H7, CD1 mice, BALB/c mice, C57BL/6 mice, faecal shedding.
The abp locus of Streptococcus uberis encodes a protein homologous to polar amino acid and opine binding proteins of Gram-negative bacteria
Authors: Jiang Min , MacLachlan P Ronald , Babiuk Lorne A , Bolton Alexandra J , Potter Andrew A
Published: April 2011

A gene locus abp was identified immediately upstream of the CAMP factor gene cfu in Streptococcus uberis. An open reading frame capable of coding for a 277-residue protein was identified. On the basis of sequence characteristics, the abp gene product is potentially a polar amino acid and opine binding component of an ATP-binding cassette type (ABC-type) transport system similar to those of Gram-negative bacteria. This membrane protein is likely lipid modified at its amino terminus and was present in five S. uberis strains and one Streptococcus parauberis strain examined.Key words: bovine mastitis, Streptococcus uberis, amino acid transport.
Thermophilic heterotrophic nitrifiers isolated from Mid-Atlantic Ridge deep-sea hydrothermal vents
Authors: Mével Geneviève , Prieur Daniel
Published: April 2011

Thermophilic heterotrophic nitrifiers were isolated for the first time from deep-sea hydrothermal vents. Fluid and chimney samples were taken at Snakepit (Mid-Atlantic Ridge) and nitrifiers were isolated from various parts of the hydrothermal ecosystem. However, most of these isolates originated from chimney samples and seemed to be mainly located in the inner and outer parts of the upper layers. All of them were rod-shaped cells, with or without spores, that grew aerobically at 65°C. Under aerobic conditions, they were able to produce nitrite from organic matter via ammonia (heterotrophic nitrification) but also from nitrate (reduction). Thus, they could largely contribute to the nitrogen cycle. These thermophilic heterotrophic nitrifiers were characterized by a considerable diversity and a phenotypic study has shown that they were closely related to the genera Thermus and Bacillus.Key words: thermophilic bacteria, heterotrophic nitrification, hydrothermal vents, deep-sea.
Quantitative relationships among thaxtomin A production, potato scab severity, and fatty acid composition in Streptomyces
Authors: Kinkel Linda L , Bowers John H , Shimizu Kyoko , Neeno-Eckwall Eric C , Schottel Janet L
Published: April 2011

Thaxtomin A production in culture, potato common scab severity (percentage of tuber surface infected or number of lesions per tuber), and fatty acid profiles were determined for 78 Streptomyces isolates. Only pathogenic Streptomyces spp. (n = 17) produced thaxtomin A in culture. Thaxtomin A production in culture (µg/mL) was significantly positively correlated with the percentage of tuber surface infected (R = 0.60; p = 0.017) but not with the number of lesions per tuber (R = 0.37; p = 0.17). An increase of 1 µg/mL in thaxtomin A production corresponded to an 11% increase in disease severity (percentage of tuber surface infected). The data indicate that quantitative information on the ability of a particular pathogen isolate or population to produce thaxtomin A may be critical to understanding and predicting the disease potential of that population. Using cluster analysis of fatty acid data, 94% of 67 unknown field isolates grouped with other field isolates having the same pathogenicity (plus or minus).Key words: thaxtomin A, phytotoxin, potato scab.
Bacillus subtilis BS 107 as an antagonist of potato blackleg and soft rot bacteria
Authors: Sharga B M , Lyon G D
Published: April 2011

Antimicrobial substances were produced by Bacillus subtilis BS 107 in a defined medium and isolated from culture filtrate by precipitation at pH 2.5. Active fractions were extracted in ethyl acetate, acetone, and 80% ethanol and purified by thin-layer chromatography (TLC) on silica gel plates developed with an ethanol-water mixture (2:1, v/v). In each case, a band with a Rf of 0.75 formed an inhibitory zone when the TLC plates were placed in contact with agar seeded with test cultures of the Erwinia spp. The antibiotic was released into the culture medium during early stages of growth of Bacillus subtilis BS 107 but higher amounts were released in older cultures. The antibiotic was resistant to the action of nucleases, proteases, and lipase. It was stable when autoclaved twice for 35 min at 2 atm (1 atm = 101.325 kPa) in acidic, neutral, and alkaline solutions. It remained active over the pH range of 1-14 during 1 month of observation and exhibited no loss of antimicrobial activity when stored at 4°C for over 1 year. Bacillus subtilis BS 107 showed activity in vitro and in vivo against Erwinia carotovora subsp. atroseptica and Erwinia carotovora subsp. carotovora, the causal agents of potato blackleg and tuber soft rot. The application of an antagonist or its antibiotic to cut potato tissues prevented or reduced symptoms of the diseases. The antibiotic was active in vitro against a broad spectrum of bacterial and fungal species.Key words: antagonist, Bacillus subtilis BS 107, Erwinia carotovora, potato.
Isolation of bacteria that decompose major polysaccharides in the cell wall of the marine red alga Porphyra yezoensis and their application for protoplast production
Authors: Yamasaki Takashi , Miyazaki Yuka , Kamei Yuto
Published: April 2011

We attempted to screen for bacteria that could decompose major polysaccharides in the cell wall of the marine red alga Porphyra yezoensis from Porphyra-culturing farms to enable simple and high-yield preparation of protoplasts with the crude enzyme from a single bacterial origin. A total of 275 positive bacterial strains were isolated by enrichment culture supplemented with Porphyra powder or xylan. Nine strains were capable of producing protoplasts from Porphyra thalli in a 10-fold concentrated culture broth. These strains were identified as two Flavobacterium spp., one Alteromonas sp., four Acinetobacter spp., and two Vibrio spp. The crude enzymes of these bacteria could release 106 protoplast cells from 0.1 g of Porphyra thalli. The crude enzyme from Alteromonas sp. strain ND137 produced the most protoplasts among the nine strains tested. Moreover, an assay of the crude enzymes from the nine bacterial strains for glycosidase activity against four major polysaccharides (xylan, mannan, porphyran, and cellulose) of P. yezoensis revealed strong decomposing activity against these polysaccharides. Xylanase activity was highest in these glycosidases, suggesting that xylanase might be a very important factor in producing protoplasts from Porphyra thalli.Key words: Porphyra, cell wall, bacteria, decomposing polysaccharide.
Differential gene expression in Azospirillum brasilense Cd under saline stress
Authors: Jofré Edgardo , Rivarola Viviana , Balegno Héctor , Mori Gladys
Published: April 2011

Previous studies in our laboratory demonstrated that the attachment of Azospirillum brasilense Cd to maize and wheat roots was altered when the bacteria were grown under saline stress. The aim of this work was to analyze the interaction when either the plant or both components were exposed to saline conditions. We demonstrated that this stress altered the early stages of development, in this plant model, leading to an inadequate colonization. The effect of saline stress on the expression of A. brasilense N2 fixation gene promoters was also studied. While nifA expression was increased in stressed bacteria, nifH transcription was diminished, suggesting an alteration in the NifA activation process. The induction of the nif gene transcription by root exudates was investigated, and the results suggest that they could be modulating certain bacterial processes, such as nitrogen fixation. However, stressed bacteria did not respond to the exudate's action. This could be related to the modified membrane composition resulting from changes in proteins, glucans, and capsular, exo- and lipopolysaccharides. We conclude that saline stress alters the Azospirillum brasilense Cd - maize interaction, the normal colonization, and the nitrogen fixation process.Key words: Azospirillum brasilense, saline stress, Azospirillum-root interaction, exudates, nif genes.
Partial characterization of an extracellular β-fructofuranosidase from Clavibacter michiganensis subspecies sepedonicus
Authors: Baer Debra , White Alan R , Gudmestad Neil C
Published: April 2011

Clavibacter michiganensis subsp. sepedonicus, a phytopathogenic bacteria isolated from potato and sugar beet, produces an extracellular β-fructofuranosidase inducible by sucrose, glucose, fructose, mannose, galactose, and raffinose. This enzyme, also known as invertase or sucrase (β-D-fructofuranoside fructohydrolase, EC 3.2.1.26), is found in the supernatant of C. michiganensis subsp. sepedonicus broth cultures. The maximal sucrase activity in the culture medium was observed after 96 h of incubation. Very little of this enzyme was associated with the cells. The enzymatic activity in the supernatant was concentrated by ethanol precipitation and further purified by a procedure that included polyethylene glycol 1450 aqueous phase partition and preparative isoelectric focusing as the main steps. Enzyme preparations were separated into two fractions (I and II) by gel-filtration chromatography. The preparative isoelectric focusing of the native enzyme showed that most activity was concentrated in the pI range of 4.0-5.0. The enzyme hydrolyzed sucrose, raffinose, and stachyose but hydrolyzed very little inulin, levan, cellobiose, lactose, maltose, or melezitose. The enzyme demonstrated glucosyltransferase activity toward [U-14C]sucrose, cleaving the disaccharide into glucose and fructose, with a small amount incorporated into a trisaccharide.Key words: levansucrase, glucosyltransferase, sucrase, dextransucrase, Solanum tuberosum
Kytococcus sedentarius (formerly Micrococcus sedentarius) and Dermacoccus nishinomiyaensis (formerly Micrococcus nishinomiyaensis) produce monensins, typical Streptomyces cinnamonensis metabolites
Authors: Pospísil S , Benada O , Kofronová O , Petrícek M , Janda L , Havlícek V
Published: April 2011

The environmental isolate Kytococcus sedentarius TR-2 was found to be a new producer of the oligoketide antibiotics monensin A and B. Electron microscopic studies demonstrated that the TR-2 strain had coccoid cells and DNA analysis revealed no close relationship to Streptomyces cinnamonensis, a typical monensin producer. Production of monensins was also proven with six culture collection K. sedentarius strains and three Dermacoccus nishinomiyaensis strains. The secondary metabolism of micrococci demonstrates a high degree of instability. Biosynthesis of monensins by micrococci endorses a phylogenetic relationship to Streptomyces spp.Key words: Kytococcus sedentarius, Dermacoccus nishinomiyaensis, Streptomyces cinnamonensis, monensins, phylogenesis.
Isolation of an Aureobasidium pullulans polysaccharide that promotes adhesion of blastospores to water-borne paints
Authors: Bardage Stig L , Bjurman Jonny
Published: April 2011

A polysaccharide composed of maltotriose units was isolated from a liquid culture of Aureobasidium pullulans (De Bary) Arnaud blastospores incubated for 4 h, by precipitation with tetrahydrofuran on solvent-resistant membranes. The concentration of polysaccharide obtained from the liquid cultures after incubation of approximately 106 spores/mL was estimated to be 2 μg/mL of culture filtrate. This polysaccharide seems to be pullulan, as judged by degradation with pullulanase. Newly harvested blastospores resuspended in water did not adhere to the surface of painted wood. However, suspensions of purified culture extract enhanced the adhesion of newly harvested blastospores to the surface of painted wood. It is therefore concluded that pullulan is released by blastospores and contributes to the adhesion of blastospores to surfaces.Key words: adhesion, spores, polysaccharide, pullulan, coatings, blue stain.
Effects of two diamine biocides on the microbial community from an oil field
Authors: Telang Anita J , Ebert Sara , Foght Julia M , Westlake Donald WS , Voordouw Gerrit
Published: April 2011

The effects of diamine (R1-NH-R2-NH2) biocides A and B on the microbial population from an oil field were investigated with reverse sample genome probing (RSGP), a technique designed to track multiple oil field bacteria in a single assay. RSGP studies of sessile microbial populations scraped from corrosion coupons obtained from biocide-treated oil field installations indicated dominance of Desulfovibrio spp. Lac6 and Eth3, or of selected heterotrophs. RSGP of planktonic production water samples indicated a broad distribution of microorganisms that changed with the addition of medium for the growth of sulfate-reducing bacteria, containing different organic acids as electron donors for sulfate reduction. Use of lactate, propionate, or acetate enriched Desulfovibrio spp., Desulfobulbus sp. Pro4, or Desulfobacter spp., respectively. Treatment of lactate- or mixed organic acid-fed planktonic populations with biocides indicated resistance of Lac6 and Eth3 to 400 ppm of biocide B and 40 ppm of biocide A. The dominance of these two Desulfovibrio spp. in many sessile field samples is, therefore, likely caused by biocide selection.Key words: Desulfovibrio, sulfate reduction, microbial corrosion, souring, biocide.
Turning on and turning off the arginine deiminase system in oral streptococci
Authors: Curran Timothy M , Ma Yousheng , Rutherford Glen C , Marquis Robert E
Published: April 2011

The arginine deiminase system in oral streptococci is highly regulated. It requires induction and is repressed by catabolites such as glucose or by aeration. A comparative study of regulation of the system in Streptococcus gordonii ATCC 10558, Streptococcus rattus FA-1, and Streptococcus sanguis NCTC 10904 showed an increase in activity of the system in S. sanguis of some 1467-fold associated with induction-derepression of cells previously uninduced-repressed. The activity of the system was assayed in terms of levels of arginine deiminase, the signature enzyme of the system, in permeabilized cells. Increases in enzyme levels associated with induction-derepression were less for the other two organisms, mainly because of less severe repression, especially for S. rattus FA-1, which was the least sensitive to catabolite repression or aeration. Regulation of the arginine deiminase system involving induction and catabolite repression was demonstrated also with monoorganism biofilms composed of cells of S. sanguis adherent to glass slides. Fully uninduced-repressed cells from suspension cultures or biofilms were compromised in their abilities to catabolize arginine to protect themselves against acid damage. However, it was found that the system can be rapidly turned on or turned off, although induction-derepression did appear to require cell growth. Still, the system could respond rapidly to the availability of arginine to reestablish high capacity for alkali production.Key words: arginine deiminase, oral streptococci, induction-derepression, acid damage, biofilms.
Use of yellow-pigmented enterococci as a specific indicator of human and nonhuman sources of faecal pollution
Authors: Bahirathan Mahesan , Puente Lawrence , Seyfried Patricia
Published: April 2011

Antibiotic susceptibility tests and restriction enzyme analysis (REA) of genomic DNA were performed to characterize the relationship between sources of isolates of yellow-pigmented enterococci. Antibiotic susceptibility tests were conducted with 10 therapeutic antibiotics and 54 isolates grouped by source (wild and other) depending on their origin. In three antibiotics, cephalothin, erythromycin, and vancomycin, there was a significant (p =< 0.05) association between susceptibility and source. Vancomycin resistance was significantly (p =< 0.001) higher in isolates from wild sources compared with that in isolates from other sources. The REA technique was performed on genomic DNA obtained from 17 Enterococcus mundtii isolates from: human (3), dog (4), horse (4), Canada goose (4), domestic goose (1), and Enterococcus mundtii ATCC 43186. A total of 12 different DNA types (A-L) were identified. Except for type D, 11 DNA types were unique and were distributed among dog (A, B, and C), human (E), horse (F, G, and H), Canada goose (I, J, and K), and domestic goose (L). Results suggested that vancomycin-susceptibility testing of yellow-pigmented enterococci may have potential value in the identification of sources of faecal pollution, especially when combined with traditional quantitative methods.Key words: yellow-pigmented enterococci, faecal pollution, antibiotic susceptibility, DNA typing.
Isolation of an asporogenic (spoOA) protective antigen-producing strain of Bacillus anthracis
Authors: Worsham Patricia L , Sowers Michele R
Published: April 2011

We found that Congo red agar allows identification of sporulation-deficient Bacillus anthracis. Using Congo red agar, we isolated an asporogenic derivative of the protective antigen-producing strain B. anthracis deltaSterne-1(pPA102). Polymerase chain reaction and Southern hybridization analyses of DNA from the asporogenic mutant revealed that a deletion was present in spoOA, an essential gene for the initiation of sporulation. The deletion also encompassed the spoIVB homologue and a portion of the recN homologue. The avirulent spoOA strain deltaSterne-1(pPA102)CR4 is suitable for the safe production of protective antigen without endospore contamination of the vaccine production facility.Key words: Bacillus anthracis, protective antigen, spoOA, vaccine, Congo red.
A basal-defined medium for the study of proteolytic activity of Serratia marcescens
Authors: Bromke Bruno J , Venuti Elaine
Published: April 2011

A simple defined basal medium is presented for the study of proteolytic activity, induction and repression, and protease purification with Serratia marcescens. Since the medium contains no protein, it does not interfere with or present artifact to protein assays, column chromatography, or electrophoresis. The medium consists of the basal salts and buffer medium of Bromke and Hammel (1979) plus a carbon-energy source such as glycerol, calcium chloride for the cation requirement for protease activity, and an amino acid, preferably leucine. Growth parameters and proteolytic activities are presented for unsupplemented medium and for the medium supplemented with each of 18 amino acids. Unsupplemented medium completes the logarithmic phase in 12.5 h of incubation and has a constitutive level of proteolytic activity. Supplementation with any amino acid, except cysteine and tryptophan, increases significantly the proteolytic activity, but has a varied effect on growth parameters.Key words: Serratia marcescens, growth, proteolytic activity, amino acids, leucine.
Isolation and purification of a Campylobacter upsaliensis autolysin
Authors: Santiwatanakul Somchai , Krieg Noel R
Published: April 2011

Autolytic activity in the soluble and sediment fractions of sonicates of the spiral and the coccoid form of Campylobacter upsaliensis could not be demonstrated by native (nondenaturing) polyacrylamide gel electrophoresis (PAGE). Autolysins were detected, however, by using denaturing sodium dodecyl sulfate (SDS) - PAGE gels containing either purified Escherichia coli peptidoglycan or whole cells of Micrococcus luteus (Micrococcus lysodeikticus) as the turbid substrate, with subsequent renaturation by treatment with Triton X-100 buffer. In renaturing gels that contained Escherichia coli peptidoglycan, 14 putative autolytic bands ranging from 200 to 12 kDa were detected. In similar gels containing whole cells of M. luteus, only a single band appeared with a molecular mass of 34 kDa. This band corresponded to one of the bands present in the gels containing Escherichia coli peptidoglycan. This common autolysin was isolated by adsorbing it from Campylobacter upsaliensis soluble fractions onto M. luteus cells and then subjecting these cells to renaturing SDS-PAGE in gels containing Escherichia coli peptidoglycan. The 34-kDa autolysin differed from a single 51-kDa autolysin unique to the M. luteus cells, and when isolated from an SDS-PAGE gel, was pure when tested by isoelectric focusing. The N-terminal amino acid sequence analysis showed the first 15 amino acids of the 34-kDa autolysin to have 67% identity to a part of antigenic protein PEB4 of Campylobacter jejuni. The purified autolysin was used to immunize rabbits and the antibodies produced precipitated autolytic activity from cell lysates. The specificity of the antibodies was shown by Western blotting: only a single specific band occurred, with a molecular mass of 34 kDa, and thus it seems unlikely that the 34-kDa autolysin was derived from any of the other autolysins that were detected.Key words: autolysin, Campylobacter upsaliensis, zymogram, murein hydrolase.
Restriction fragment length polymorphism analysis of psychrophilic and psychrotrophic Vibrio and Photobacterium from the north-western Pacific Ocean and Otsuchi Bay, Japan
Authors: Urakawa Hidetoshi , Kita-Tsukamoto Kumiko , Ohwada Kouichi
Published: April 2011

Typing and identification of 60 marine psychrophilic and psychrotrophic vibrios isolated from the north-western Pacific Ocean and coastal environment of Japan were performed by restriction fragment length polymorphism analysis on the basis of polymerase chain reaction amplified 16S rDNA. We obtained 15 operational taxonomic units (OTUs) by digestion with four restriction endonucleases (HhaI, DdeI, RsaI, and Sau3AI); four large groups were obtained from the neighbor-joining method. Significant differences were observed in OTU composition between isolates from the deep sea and coastal areas. Vibrio marinus and Photobacterium species were the dominant culturable vibrios in the deep sea areas, while Vibrio splendidus like species were the dominant culturable vibrios in a coastal area of Japan.Key words: restriction analysis, Vibrio, Photobacterium, Vibrio marinus (Moritella marina), Vibrio splendidus.
Persistence of suppression effects on peatland black spruce advance regeneration after overstory removal
Authors: Groot Arthur , Hökkä Hannu
Published: April 2011

The persistence of suppression effects on peatland black spruce (Picea mariana (Mill.) BSP) advance regeneration following overstory removal was examined (i) by analyzing post-harvest growth patterns and (ii) by comparing observed post-harvest growth with predictions from an individual-tree growth model. Analysis of growth patterns revealed critical points (inflections or maxima) in annual basal area, diameter, and height growth series, and in specific volume increment. Critical points occurred at different times (ranging from 1 to 29 years after harvest) for different variables and often occurred earlier for trees with greater height at time of harvest. These critical points do not necessarily coincide with the cessation of persisting suppression, however, since post-harvest growth patterns also reflect current influences on growth. The comparison of observed basal area and diameter growth with model predictions isolated persisting suppression effects. The effects of suppression on basal area and diameter growth decline linearly with time since harvest and become negligible 12 years after harvest. The persistence of suppression effects on basal area and diameter growth is largely independent of the height of the tree at the time of harvest.
Bird communities associated with live residual tree patches within cut blocks and burned habitat in mixedwood boreal forests
Authors: Schieck Jim , Hobson Keith A
Published: April 2011

By retaining patches of trees in cut blocks, managers expect to retain some forest birds and create bird communities more similar to those found after fires. We surveyed birds from a range of patch sizes (1 to >3000 live residual trees), at four ages (2, 15, 30, 60 years), following two disturbance types (harvest, fire) in mixedwood boreal forest. Bird communities varied among patch sizes, forest ages, and disturbance types. Immediately post-disturbance, bird communities from large patches (>100 residual trees) were more similar to those from old forest than were communities from small patches ([Formula: see text]10 residual trees). Birds that nest or forage in open or riparian habitats had highest densities in small patches 2 years post-harvest, whereas birds that nest in large snags had highest densities in small patches 2 years post-fire. Throughout the chronosequence following both disturbance types, birds from small patches became more similar to those from old forest. Birds that nest and forage in small trees and shrubs were common 15 and 30 years post-disturbance, and generalist forest birds were common 60 years post-disturbance. Birds associated with old forest were present in all patch sizes 15, 30, and 60 years post-disturbance, although larger patches had higher densities of these species.
Using foliar variables to predict the response of lodgepole pine to nitrogen and sulphur fertilization
Authors: Brockley R P
Published: April 2011

Six-year basal area responses to nitrogen (N) fertilizer, alone and in combination with sulphur (S), in 31 lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) stands in the interior of British Columbia were compared with pre-treatment measures of foliar N and S and first-year increases in fascicle mass to determine the utility of these variables for predicting growth response and for determining appropriate fertilizer prescriptions. Results indicate that pre-fertilization levels of foliar N or inorganic sulphate-S (SO4) may be more reliable than the fascicle mass screening method for predicting whether or not a significant stemwood response will occur following N fertilization. When combined, N and SO4 levels in unfertilized foliage explained 68% of the variation in relative basal area response to fertilization with N alone. Foliar nutrients were also useful for determining whether or not lodgepole pine would respond incrementally to S when added in combination with N. Stands in which pre-fertilization foliar SO4 was [Formula: see text]60 mg/kg and N/S ratio was [Formula: see text]13 did not respond significantly to N alone but always responded significantly to N + S. Conversely, a foliar SO4 level >60 mg/kg combined with a N/S ratio of [Formula: see text]12 always resulted in a favourable response to N with no incremental benefit of added S.
Modeling self-thinning of unthinned Lake States red pine stands using nonlinear simultaneous differential equations
Authors: Turnblom Eric C , Burk Thomas E
Published: April 2011

Forest management demands thorough knowledge of ecological systems. Tree interaction dynamics are one component of these ecological systems. Developing growth models which incorporate ecological "laws" such as the self-thinning rule can lead to better understanding of the laws, to better understanding of what is still unknown, and to what is in need of refinement. To this end a system of simultaneous differential equations incorporating logical, linked hypotheses regarding growth and mortality is proposed and fit to data from red pine (Pinus resinosa Ait.) plantations in the Lake States (Minnesota, Michigan, and Wisconsin). Using this modeling framework it appears that stand initiation history has a large impact on the level of the self-thinning boundary for red pine growing in the Lake States. Stands with initially high density exhibited lower self-thinning boundaries than stands with lower densities. Site quality (as measured by site index) chiefly affected the rate at which stand dynamics progress. Higher quality sites progressed through stand development at faster rates than did sites with lower quality.