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Jonathan P Wright

Publications and source records attributed to Jonathan P Wright.

9 recordsLinked to original sources
PubMed2006

ATP level variations in heterotrophic bacteria during attachment on hydrophilic and hydrophobic surfaces.

A survey of the extracellular ATP levels of 86 heterotrophic bacteria showed that gram-negative bacteria of the genera Sulfitobacter, Staleya, and Marinobacter secreted elevated amounts of extracellular ATP, ranging from 6.0 to 9.8 pM ATP/colony forming unit (cfu), and that gram-positive bacteria of the genera Kocuria and Planococcus secreted up to 4.1 pM ATP/cfu. Variations in the levels of extracellular and intracellular ATP-dependent luminescence were monitored in living cells of Sulfitobacter mediterraneus ATCC 700856T and Planococcus maritimus F 90 during 48 h of attachment on hydrophobic (poly[tert-butyl methacrylate], PtBMA) and hydrophilic (mica) surfaces. The bacteria responded to different polymeric surfaces by producing either intracellular or extracellular ATP. The level of intracellular ATP in S. mediterraneus ATCC 700856T attached to either surface was as high as 50-55 pM ATP/cfu, while in P. maritimus F 90 it was 120 and 250 pM ATP/cfu on PtBMA and mica, respectively. S. mediterraneus ATCC 700856T generated about 20 and 50 pM of extracellular ATP/cfu on PtBMA and mica, respectively, while the amount generated by P. maritimus F 90 was about the same for both surfaces, 6 pM ATP/cfu. The levels of extracellular ATP generated by S. mediterraneus during attachment on PtBMA and mica were two to five times higher than those detected during the initial screening. High-resolution atomic force microscopy imaging revealed a potentially interesting correlation between the porous cell-surface of certain alpha- and gamma-proteobacteria and their ability to secrete high amounts of ATP.

Adenosine Triphosphate↗
PubMed2005

High-throughput phase-diagram mapping via powder diffraction: a case study of HEWL versus pH.

44 samples of tetragonal hen egg-white lysozyme (HEWL) were obtained as a series of polycrystalline precipitates at 277 K and room temperature in the pH range between 6.56 and 3.33. The precipitates were investigated by the collection of high-resolution powder X-ray diffraction data at 295 K, which reveal the tetragonal or orthorhombic forms of lysozyme depending on the temperature and pH of crystallization. The use of a new robotic sample changer greatly facilitated these measurements. LeBail analyses of the powder patterns display a characteristic behaviour for the pH dependence of the tetragonal unit-cell parameters of HEWL crystallized at both temperatures. More detailed analysis shows that molecular replacement can give a suitable starting point for structural refinements, illustrating that powder data can be sufficient for this approach. Pawley or Rietveld refinements that fit a single model to four data sets simultaneously from four samples crystallized at pH values across the range studied benefit from improved powder data quality via the anisotropic changes in the unit cell. The Rietveld analysis gave an average structural model with excellent goodness of fit and stereochemistry.

Animals↗
PubMed2005

Synchrotron X-ray powder diffraction study of hexagonal turkey egg-white lysozyme.

The structure of turkey egg-white lysozyme (TEWL) has been refined from high-resolution X-ray powder diffraction data. The sample was rapidly obtained as a polycrystalline precipitate at high protein concentration using 0.5 M NaCl solvent pH 6 and was deposited in the PDB with code 1xft. The diffraction data were collected at room temperature. Molecular replacement was shown to give a suitable starting point for refinement, illustrating that powder data can be sufficient for this approach. Crystallographic models were then refined by combined Rietveld and stereochemical restraint analysis of the powder data (d(min) = 3.35 A), resulting in the extraction of reliable lattice parameters and the refinement of the molecular conformation at room temperature. The structure is hexagonal [space group P6(1)22, unit-cell parameters a = 71.0862 (3), c = 85.0276 (5) A] with 12 symmetry-related molecules in the unit cell, in agreement with previous studies. The results of our analysis are indicative of specific amino acids being disordered at this temperature. Upon cooling, a sudden drop in the lattice parameters at approximately 250 K is observed concurrently with the freezing of the mother liquor. The observation of severe peak broadening below this temperature indicates strain effects accompanying the freezing transition, which are found to be reversible. Finally, a correlation between the unit-cell parameters and the pH of the buffer solution is evident, in a similar manner to earlier observations on HEWL.

Animals↗
PubMed2004

Formosa algae gen. nov., sp. nov., a novel member of the family Flavobacteriaceae.

Four light-yellow-pigmented, Gram-negative, short-rod-shaped, non-motile isolates were obtained from enrichment culture during degradation of the thallus of the brown alga Fucus evanescens. The isolates studied were chemo-organotrophic, alkalitolerant and mesophilic. Polar lipids were analysed and phosphatidylethanolamine was the only phospholipid identified. The predominant cellular fatty acids were 15 : 0, i15 : 0, ai15 : 0, i15 : 1 and 15 : 1(n-6). The DNA G+C contents of the four strains were 34.0-34.4 mol%. The level of DNA relatedness of the four isolates was conspecific (88-98 %), indicating that they belong to the same species. The 16S rDNA sequence of strain KMM 3553(T) was determined. Phylogenetic analysis revealed that KMM 3553(T) formed a distinct phyletic line in the phylum Bacteroidetes, class Flavobacteria in the family Flavobacteriaceae and that, phylogenetically, this strain could be placed almost equidistant from the genera Gelidibacter and Psychroserpens (16S rRNA gene sequence similarities of 94 %). On the basis of significant differences in phenotypic and chemotaxonomic characteristics, it is suggested that the isolates represent a novel species in a new genus; the name Formosa algae gen. nov., sp. nov. is proposed. The type strain is KMM 3553(T) (=CIP 107684(T)).

Base Composition↗
PubMed2003

Marinobacter excellens sp. nov., isolated from sediments of the Sea of Japan.

Five strains of halophilic, Gram-negative marine bacteria (KMM 3809(T), KMM 3814, KMM 3815, KMM 3817 and KMM 3818) were isolated from sediments collected from Chazhma Bay, Sea of Japan. Phylogenetic 16S rRNA gene sequence-based analysis placed these bacteria in a clade within the genus Marinobacter in the gamma-Proteobacteria. KMM 3809(T) showed highest 16S rRNA gene sequence similarity of 97.3 % to Marinobacter litoralis and 96.9 % to Marinobacter hydrocarbonoclasticus and Marinobacter aquaeolei. DNA-DNA hybridization between the five isolates was at the conspecific level (94-96 %) and that among the closest phylogenetic neighbours ranged from 45.0 to 62.5 %. The new organisms were susceptible to polymyxin. Predominant fatty acids were C(16 : 0), C(16 : 1)omega9c, C(16 : 1)omega7c and C(18 : 1)omega9c. Phylogenetic evidence, along with phenotypic and genotypic characteristics, showed that the bacteria constituted a novel species of the genus Marinobacter. The name Marinobacter excellens sp. nov. is proposed for this species, with the type strain KMM 3809(T) (=CIP 107686(T)).

Alteromonadaceae↗
PubMed2002

Detection of coccoid forms of Sulfitobacter mediterraneus using atomic force microscopy.

The adhesion of the marine alpha-Proteobacteria Sulfitobacter pontiacus, Sulfitobacter mediterraneus, Sulfitobacter brevis, and Staleya guttiformis to a poly(tert-butyl methacrylate) (PtBMA) polymeric surface generates unusual cell morphological peculiarities following attachment. While the type strains S. pontiacus and S. brevis failed to attach to PtBMA, the vegetative cells of type strain S. mediterraneus underwent morphological conversion into coccoid forms during the attachment over an incubation period of 24-72 h. Type strain St. guttiformis cells formed a multilayered biofilm on the PtBMA surface, presumably facilitated by bacterial production of extracellular polysaccharides. The attachment behavior and fine structure of these coccoid forms have been described using atomic force microscopy. The impact of polymeric surfaces of defined hydrophobicity on the formation of coccoid bodies is discussed.

Alphaproteobacteria↗
PubMed2002

Hemodilution with albumin, but not Hextend, results in hypercoagulability as assessed by Thrombelastography in rabbits: role of heparin-dependent serpins and factor VIII complex.

UNLABELLED: Isovolemic hemodilution (IVHD) has been advocated as an effective method of reducing the need for transfusion but has been associated with hypercoagulability. We tested the hypothesis that IVHD enhances hemostatic function by decreasing circulating antithrombin activity in rabbits. Furthermore, it was determined whether different replacement solutions would affect hemostasis. Sedated rabbits were randomly assigned to groups that underwent IVHD (40% blood volume removed) with 5% human albumin (n = 10) or a 6% hetastarch solution (Hextend). Antithrombin and Factor VIII complex (VIII:C) activities were determined, and thrombelastography(R) was performed with or without platelet inhibition. IVHD resulted in a significant (P < 0.05) decrease in antithrombin (32%-39%) without fluid-specific differences observed. VIII:C did not change in the albumin group, whereas the hetastarch group had a significant (P < 0.05) decrease (43%) in VIII:C that was also significantly (P < 0.05) less than the albumin group. The time to clot initiation was decreased, and the rate of clot formation increased significantly via thrombelastography(R) in albumin animals. No significant change in clot kinetics was observed in hetastarch animals. In rabbits, the primary determinant of hemostasis after IVHD was the interaction of changes in antithrombin activity and VIII:C. These data serve as a rational basis to determine whether IVHD-mediated hypercoagulability encountered clinically may be attenuated or exacerbated by the choice of colloid administered. IMPLICATIONS: Isovolemic hemodilution (IVHD) is associated with hypercoagulability. Rabbits hemodiluted with albumin, but not Hextend, became hypercoagulable secondary to a loss of antithrombin activity with simultaneous maintenance of Factor VIII complex activity (VIII:C). Hextend-treated animals had proportionate decreases in both antithrombin activity and VIII:C. IVHD-mediated hypercoagulability encountered clinically may be attenuated or exacerbated by the choice of colloid administered.

Animals↗