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851.
Siegfried Brunner Erik Eppinger Stefanie Fischer Janosch Gröning Andreas Stolz 《World journal of microbiology & biotechnology》2018,34(7):91
The conversion of aliphatic nitriles by the arylacetonitrilase from Pseudomonas fluorescens EBC191 (NitA) was analyzed. The nitrilase hydrolysed a wide range of aliphatic mono- and dinitriles and showed a preference for unsaturated aliphatic substrates containing 5–6 carbon atoms. In addition, increased reaction rates were also found for aliphatic nitriles carrying electron withdrawing substituents (e.g. chloro- or hydroxy-groups) close to the nitrile group. Aliphatic dinitriles were attacked only at one of the nitrile groups and with most of the tested dinitriles the monocarboxylates were detected as major products. In contrast, fumarodinitrile was converted to the monocarboxylate and the monocarboxamide in a ratio of about 65:35. Significantly different relative amounts of the two products were observed with two nitrilase variants with altered reaction specifities. NitA converted some aliphatic substrates with higher rates than 2-phenylpropionitrile, which is one of the standard substrates for arylacetonitrilases. This indicated that the traditional classification of nitrilases as “arylacetonitrilases”, “aromatic” or “aliphatic” nitrilases might require some corrections. This was also suggested by the construction of some variants of NitA which were modified in an amino acid residue which was previously suggested to be essential for the conversion of aliphatic substrates by a homologous nitrilase. 相似文献
852.
作为换代产品,流行性感冒裂解疫苗的研制已取得突破性进展,根据WHO有关规程的规定和大量的试验研究结果。完整建立了该疫苗的生产工艺和生产质量控制系统,完成了“流行性感冒裂解疫苗制造及检定规程”等规定性文件的起草和审核工作,以中试规模连续生产了三批疫苗并全部自检合格,通过疫苗稳定性试验,效力试验,异常毒性试验及过敏性试验等观察。进一步肯定了疫苗的质量。 相似文献
853.
To investigate the regulatory mechanisms of sex expression in cucumber, morphological observations and biochemical analyses were carried out on inappropriate stamen development of female flowers of cucumber. It was found that developmental arrest of the inappropriate stamen mainly occurs at the anther primordium. This arrest is closely correlated with DNA damage, as detected by TUNEL assay, and might result from anther-specific DNase activation. It was also found that the DNA damage does not lead to cell degeneration, although chromatin condensation is observed in the anther primordia.Abbreviations DAPI 4,6-diamidine-2-phenylindole dihydrochloride - MTT 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide - PCD programmed cell death - TUNEL TdT-mediated dUTP nick-end labeling 相似文献
854.
855.
Yanming Sun Ruofeng Yan Charles I. Muleke Guangwei Zhao lixin Xu Xiangrui Li 《International journal of peptide research and therapeutics》2007,13(3):387-392
The effect of Haemonchus contortus galectin peptides rHco-gal-m/f to induce apoptosis in the peripheral blood lymphocytes (PBLCs) of goats was investigated. Analysis of apoptosis was
carried out with agarose gel electrophoresis, flow cytometry and transmission electron microscopy. The results indicated that
there were visible apoptosis bodies and typical DNA ladders by genomic DNA fragmentation. The quantitative analysis of apoptosis
by flow cytometry indicated that rHco-gal-m/f peptides induced apoptosis was time and dose dependent. Ultrastructural studies of the PBLCs revealed that a large
number of apoptotic cells were present in galectin-treated cells, which had the typical morphologic changes of apoptosis such
as reduction of the cytoplasmic volume, loss of cell surface microvilli, chromatin condensation and fragmentation of the apoptotic
cells into small apoptotic bodies. 相似文献
856.
DGGE fingerprinting of bacteria in soils from eight ecologically different sites around Casey Station,Antarctica 总被引:3,自引:0,他引:3
C. W. Chong G. Y. Annie Tan Richard C. S. Wong Martin J. Riddle Irene K. P. Tan 《Polar Biology》2009,32(6):853-860
Bacterial community structures in soils collected from eight sites around Casey Station, Antarctica, were investigated using
denaturing gradient gel electrophoresis (DGGE) of amplified 16S rRNA gene fragments. Higher bacterial diversity was found
in soils from protected or relatively low human-impacted sites in comparison to highly impacted sites. However, the highest
diversity was detected in samples from Wilkes Tip, a former waste disposal site that has been undisturbed for the last 50 years.
Comparison of community structure based on non-metric multidimensional scaling plots revealed that all sites, except the hydrocarbon-contaminated
(oil spill) site, were clustered with a 45% similarity. A total of 23 partial 16S rRNA gene sequences were obtained from the
excised DGGE bands, with the majority of the sequences closely related to those of the Cytophaga–Flexibacter–Bacteroides group. No significant correlation was established between environmental variables, including soil pH, electrical conductivity,
carbon, nitrogen, water content and heavy metals, with bacterial diversity across the eight study sites. 相似文献
857.
Background
Profile hidden Markov models (profile-HMMs) are sensitive tools for remote protein homology detection, but the main scoring algorithms, Viterbi or Forward, require considerable time to search large sequence databases. 相似文献858.
In this study, an aqueous extract of leaves from Melothria maderaspatana was tested for in vitro antioxidant activity. Free radical scavenging assays, such as hydroxyl radical, hydrogen peroxide, superoxide anion radical
and 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2’-azinobis-(3-ethyl-enzothiazoline-6-sulfonic acid) (ABTS) radical scavenging,
and reducing power assay, were studied. The extract effectively scavenged hydroxyl radical, hydrogen peroxide and superoxide
anion radicals. It also scavenged DPPH and ABTS radicals. Furthermore, it was found to have reducing power. All concentrations
of leaf extract exhibited free radical scavenging and antioxidant power, and the preventive effects were in a dose-dependent
manner. The antioxidant activities of the above were compared to standard antioxidants such as butylated hydroxytoluene (BHT),
ascorbic acid, and α-tocopherol. The results obtained in the present study indicate that the M. maderaspatana extract could be considered a potential source of natural antioxidant. 相似文献
859.
Valiallah Khalaji-Pirbalouty Johann-Wolfgang Wägele 《Organisms Diversity & Evolution》2010,10(2):135-145
Two new species of Ligia are described, L. persica sp. nov. from the Persian Gulf and L. yemenica sp. nov. from the Gulf of Aden. Ligia persica occurs along the northern coasts of the Persian Gulf and around some Iranian islands such as Qeshm and Kish. A comparison
of SEM micrographs shows that the shape and ornamentation of distal parts of the appendix masculina are reliable characters
for the identification of morphologically similar Ligia species. They are species-specific and of great importance in the taxonomy of the genus. 相似文献
860.
Helicobacter pylori, a microaerophilic Gram-negative bacterium, is known to cause chronic gastritis, peptic ulcer and gastric cancer. Genes that are present in certain isolates may determine strain-specific traits such as disease association and drug resistance. In order to understand the pathogenic mechanisms of gastric diseases, identify molecular markers of the diseases associated with H. pylori strains and provide clues for target treatment of H. pylori-related diseases, a subtracted DNA library was constructed from a gastric cancer-associated H. pylori strain and a superficial gastritis-associated H. pylori strain by suppression subtractive hybridization. The presence of gastric cancer-specific genes was identified by dot blot hybridization, DNA sequencing and PCR-based screening. Twelve gastric cancer-specific high-copy genes and nine low-copy genes were found in gastric cancer compared with the superficial gastritis strain. These genes were confirmed by PCR analysis of H. pylori isolates. Notably, peptidyl-prolyl cis-trans isomerase (PPIase) was detected positively in 11 out of 22 (50%) gastric cancer-associated H. pylori strains. In contrast, <24% of the H. pylori strains from superficial gastritis showed positive results. Given the potential role of PPIases in cell growth, apoptosis and oncogenic transformation, our results suggest that PPIase may represent a novel marker and potential therapeutic target for gastric cancer. 相似文献