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41.
Kenji Kinoshita Satoshi Yaginuma Mitsuo Hayashi Kazumi Nakatsu 《Nucleosides, nucleotides & nucleic acids》2013,32(5):661-668
Abstract The molecular and crystal structure of neplanocin C(3), C11H13N5O4 M.W. = 279.26, has been determined by X-ray anlys?s. The space group is P21 with a=16.381(2), b=8.210(1), c=9.127(1) Å, β=105.31(1)° and z=4. The structure was solved by direct method, and least-squares refinement using 2093 reflections with |Fo|>3σ(F) led to the final R value of 0.0772. The sugar puckering of the two crystal-lographically independent molecules is C(2′)-exo-C(3′)-endo, and the torsion angles about the N(9)-C(1′) bond are 22.8(6) and 28.7(6)°, respectively (anti conformation). 相似文献
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Matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been shown to be a rapid and sensitive method for characterization of bacteria, but it has not yet become a routine microbiological procedure. Currently there are no standardized protocols that would allow development of large libraries of reproducible protein profiles from a broad range of microorganisms to use for identification purposes. Important variables that may affect spectrum quality are MALDI matrices, solvents, cell growth condition, and culture age. In the present study our aim was to: (1) to determine optimal sample preparation and MALDI conditions for discrimination at the strain level; (2) to determine if changes in growth cycle correlated with MALDI spectrum changes; and (3) to compare level of isolate discrimination based on their MALDI spectra versus their 16S rRNA gene sequence. Using 16 strains of the Gram positive bacterium Arthrobacter, optimal spectra were obtained using two-layer sample application of intact cells grown on solid surface overlaid with a matrix consisting of sinapinic acid (SA) or alpha-cyano-hydroxy-cinnaminic acid (CHCA) in 50:50 acetonitrile:water solvent with 2% trifluoroacetic acid. Spectrum changes paralleled the coccus-rod-coccus growth cycle indicative of Arthrobacter. Strain differences based on their MALDI profiles (using Pearson coefficient and UPGMA) corresponded with their 16S rRNA gene phylogeny but it had greater discrimination. 相似文献
44.
Bacterial Activity, Community Structure, and Centimeter-Scale Spatial Heterogeneity in Contaminated Soil 总被引:5,自引:0,他引:5
In an anthropogenically disturbed soil (88% sand, 8% silt, 4% clay), 150-mg samples were studied to examine the fine-scale
relationship of bacterial activity and community structure to heavy metal contaminants. The soils had been contaminated for
over 40 years with aromatic solvents, Pb, and Cr. Samples from distances of <1, 5, 15, and 50 cm over a depth range of 40–90 cm
underwent a sequential analysis to determine metabolic potential (from 14C glucose mineralization), bacterial community structure [using polymerase chain reaction-denaturing gradient gel electrophoresis
(PCR-DGGE)], and total extractable Pb and Cr levels. Metabolic potential varied by as much as 10,000-fold in samples <1 cm
apart; log–log plots of metal concentration and microbial metabolic potential showed no correlation with each other. Overall,
metal concentrations ranged from 9 to 29,000 mg kg−1 for Pb and from 3 to 8500 mg kg−1 for Cr with small zones of high contamination present. All regions exhibited variable metal concentrations, with some soil
samples having 30-fold differences in metal concentration in sites <1 cm apart. Geostatistical analysis revealed a strong
spatial dependence for all three parameters tested (metabolic activity, Pb, and Cr levels) with a range up to 30 cm. Kriging
maps showed that in zones of high metal, the corresponding metabolic activity was low suggesting that metals negatively impacted
the microbial community. PCR-DGGE analysis revealed that diverse communities were present in the soils with a random distribution
of phylotypes throughout the sampling zones. These results suggest the presence of spatially isolated microbial communities
within the soil profile. 相似文献
45.
Background
Two-dimensional data colourings are an effective medium by which to represent three-dimensional data in two dimensions. Such "color-grid" representations have found increasing use in the biological sciences (e.g. microarray 'heat maps' and bioactivity data) as they are particularly suited to complex data sets and offer an alternative to the graphical representations included in traditional statistical software packages. The effectiveness of color-grids lies in their graphical design, which introduces a standard for customizable data representation. Currently, software applications capable of generating limited color-grid representations can be found only in advanced statistical packages or custom programs (e.g. micro-array analysis tools), often associated with steep learning curves and requiring expert knowledge. 相似文献46.
We have made xeroderma pigmentosum group A gene (XPA)-knockout mice (XPA(-/-) mice). The XPA(-/-) mice had no detectable activity for nucleotide excision repair (NER) and showed a high incidence of UVB-induced skin tumorigenesis. We have also found that cell lines derived from skin cancers in UVB-irradiated XPA(-/-) mice become tolerant to UV-irradiation and showed abnormal UV-induced cell cycle checkpoints and decreased mismatch repair (MMR) activity. These results suggested that the MMR-downregulation may help cells escape killing by UV-irradiation and thus MMR-deficient clones are selected for during the tumorigenic transformation of XPA(-/-) cells. In this report, we examined whether the incidence of UVB-induced skin tumorigenesis is enhanced in XPA(-/-)MSH2(-/-), XPA(-/-) and MSH2(-/-) mice when compared with that in wild-type mice. Our results indicate that the MSH2-deficiency caused a high incidence of spontaneous and UVB-induced skin tumorigenesis and the XPA and MSH2 genes have additive roles in the UV-induced skin tumorigenesis. 相似文献
47.
Heme plays a critical role in blood pressure regulation because it is required by a number of enzymes that synthesize vascular modulators, including nitric oxide (NO), carbon monoxide (CO), guanosine 3',5'-cyclic monophosphate (cGMP), endothelium-derived hyperpolarizing factor (EDHF), and prostacyclin. The goal of this study was to examine the vascular effects of a short-term depletion of heme achieved through administration of the heme-synthesis inhibitor succinylacetone (SA), an irreversible inhibitor of aminolevulinic acid dehydratase (ALAD). Rats were depleted of heme by using a 4-day treatment with SA. This treatment impacted hemoenzyme function, decreasing renal nitric oxide synthase (NOS) activity (as indicated by decreased in vitro NOS activity), and increasing kidney microsomal heme oxygenase (HO) activity by 27%. SA treatment also resulted in enhanced reduction in blood pressure after infusions of exogenous NO donor MAHMA NONOate (at high dose) and acetylcholine (at low doses). Nevertheless, this SA treatment was insufficient to produce an overt elevation of basal arterial pressure. This latter lack of effect may be the result of multiple compensatory mechanisms for the regulation of blood pressure. 相似文献
48.
Anacardic acid-mediated changes in membrane potential and pH gradient across liposomal membranes. 总被引:1,自引:0,他引:1
Masaaki Toyomizu Katsuyuki Okamoto Yukio Akiba Tetsuo Nakatsu Tetsuya Konishi 《Biochimica et biophysica acta》2002,1558(1):54-62
We have previously shown that anacardic acid has an uncoupling effect on oxidative phosphorylation in rat liver mitochondria using succinate as a substrate (Life Sci. 66 (2000) 229-234). In the present study, for clarification of the physicochemical characteristics of anacardic acid, we used a cyanine dye (DiS-C3(5)) and 9-aminoacridine (9-AA) to determine changes of membrane potential (DeltaPsi) and pH difference (DeltapH), respectively, in a liposome suspension in response to the addition of anacardic acid to the suspension. The anacardic acid quenched DiS-C3(5) fluorescence at concentrations higher than 300 nM, with the degree of quenching being dependent on the log concentration of the acid. Furthermore, the K(+) diffusion potential generated by the addition of valinomycin to the suspension decreased for each increase in anacardic acid concentration used over 300 nM, but the sum of the anacardic acid- and valinomycin-mediated quenching was additively increasing. This indicates that the anacardic acid-mediated quenching was not due simply to increments in the K(+) permeability of the membrane. Addition of anacardic acid in the micromolar range to the liposomes with DeltaPsi formed by valinomycin-K(+) did not significantly alter 9-AA fluorescence, but unexpectedly dissipated DeltaPsi. The DeltaPsi preformed by valinomycin-K(+) decreased gradually following the addition of increasing concentrations of anacardic acid. The DeltaPsi dissipation rate was dependent on the pre-existing magnitude of DeltaPsi, and was correlated with the logarithmic concentration of anacardic acid. Furthermore, the initial rate of DeltapH dissipation increased with logarithmic increases in anacardic acid concentration. These results provide the evidence for a unique function of anacardic acid, dissimilar to carbonylcyanide p-trifluoromethoxyphenylhydrazone or valinomycin, in that anacardic acid behaves as both an electrogenic (negative) charge carrier driven by DeltaPsi, and a 'proton carrier' that dissipates the transmembrane proton gradient formed. 相似文献
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50.
Joint Report of the First International Comparison Test on Swine Lymphocyte Alloantigens (SLA) 总被引:5,自引:0,他引:5
CH. RENARD B. KRISTENSEN C. GAUTSCHI V. HRUBAN M. FREDHOLM M. VAIMAN 《Animal genetics》1988,19(1):63-72
The first international comparison test on swine lymphocyte alloantigens (SLA) was held in Helsinki, Finland in July 1986. The results reported were based on a comparison of 157 alloantisera originating from six laboratories. The antisera were tested against a selected panel of 264 lymphocyte samples belonging to four laboratories. The most common breeds in Europe were chosen for this first comparison test (Landrace and Large White). Eighteen of the 31 previously known specificities were confirmed and a new nomenclature was established. 相似文献