A total of 1500 environmental strains of Vibrio parahaemolyticus, isolated from the aquatic environment of Bangladesh, were screened for the presence of a major V. parahaemolyticus virulence factor, the thermostable direct haemolysin (tdh) gene, by the colony blot hybridization method using a digoxigenin-labeled tdh gene probe. Of 1500 strains, 5 carried the tdh sequence, which was further confirmed by PCR using primers specific for the tdh gene. Examination by PCR confirmed that the 5 strains were V. parahaemolyticus and lacked the thermostable direct haemolysin-related haemolysin (trh) gene, the alternative major virulence gene known to be absent in pandemic strains. All 5 strains gave positive Kanagawa phenomenon reaction with characteristic beta-haemolysis on Wagatsuma agar medium. Southern blot analysis of the HindIII-digested chromosomal DNA demonstrated, in all 5 strains, the presence of 2 tdh genes common to strains positive for Kanagawa phenomenon. However, the 5 strains were found to belong to 3 different serotypes (O3:K29, O4:K37, and O3:K6). The 2 with pandemic serotype O3:K6 gave positive results in group-specific PCR and ORF8 PCR assays, characteristics unique to the pandemic clone. Clonal variations among the 5 isolates were analyzed by comparing RAPD and ribotyping patterns. Results showed different patterns for the 3 serotypes, but the pattern was identical among the O3:K6 strains. This is the first report on the isolation of pandemic O3:K6 strains of V. parahaemolyticus from the aquatic environment of Bangladesh. 相似文献
Abstract The syntheses of three classes of adenosine analogues involving cyclosubstitution at the 6-position and functionalization at the 2-position are reported. The target molecules synthesized are stable with respect to hydrolytic deamination by mammalian adenosine deaminase, and, because of major structural changes at the 2- and 6-positions, these compounds are expected to be poor phosphorylation substrates for the kinases. Adenosine receptor binding data reveal that several of the compounds synthesized show excellent A1 receptor affinity and A2/A1 selectivity. 相似文献
Journal of Biological Physics - The paper delves into the plausibility of applying fractal, spectral, and nonlinear time series analyses for lung auscultation. The thirty-five sound signals of... 相似文献
In insects infections trigger hemocyte-mediated immune reactions including degranulation by exocytosis; however, involvement of mediator enzymes in degranulation process is unknown in insects. We report here that in silkworm Bombyx mori, infection by endoparasitoid Exorista bombycis and microsporidian Nosema bombycis activated granulation in granulocytes and promoted degranulation of accumulated structured granules. During degranulation the mediator lysosomal enzyme β-hexosaminidase showed increased activity and expression of β-hexosaminidase gene was enhanced. The events were confirmed in vitro after incubation of uninfected hemocytes with E. bombycis larval tissue protein. On infection, cytotoxicity marker enzyme lactate dehydrogenase (LDH) was released from the hemocytes illustrating cell toxicity. Strong positive correlation (R2?=?0.71) between LDH activity and β-hexosaminidase released after the infection showed parasitic–protein-induced hemocyte damage and accompanied release of the enzymes. Expression of β-hexosaminidase gene was enhanced in early stages after infection followed by down regulation. The expression showed positive correlation (R2?=?0.705) with hexosaminidase activity pattern. B. mori hexosaminidase showed 98% amino acid similarity with that of B. mandarina showing origin from same ancestral gene; however, 45–60% varied from other lepidopterans showing diversity. The observation signifies the less known association of hexosaminidase in degranulation of hemocytes induced by parasitic infection in B. mori and its divergence in different species.
The synthesis of Zinc oxide nanoparticles using a plant-mediated approach is presented in this paper. The nanoparticles were successfully synthesized using the Nitrate derivative of Zinc and plant extract of the indigenous medicinal plant Cayratia pedata. 0.1 mM of Zn (NO3)2.6H2O was made to react with the plant extract at different concentrations, and the reaction temperature was maintained at 55 °C, 65 °C, and 75 °C. The yellow coloured paste obtained was wholly dried, collected, and packed for further analysis. In the UV visible spectrometer (UV–Vis) absorption peak was observed at 320 nm, which is specific for Zinc oxide nanoparticles. The characterization carried out using Field Emission Scanning Electron Microscope (FESEM) reveals the presence of Zinc oxide nanoparticles in its agglomerated form. From the X-ray diffraction (XRD) pattern, the average size of the nanoparticles was estimated to be 52.24 nm. Energy Dispersive Spectrum (EDX) results show the composition of Zinc and Oxygen, giving strong energy signals of 78.32% and 12.78% for Zinc and Oxygen, respectively. Fourier Transform - Infra-Red (FT-IR) spectroscopic analysis shows absorption peak of Zn–O bonding between 400 and 600 cm?1. The various characterization methods carried out confirm the formation of nano Zinc oxide. The synthesized nanoparticles were used in the immobilization of the enzyme Glucose oxidase. Relative activity of 60% was obtained when Glucose oxidase was immobilized with the green synthesized ZnO nanoparticles. A comparative study of the green synthesized with native ZnO was also carried out. This green method of synthesis was found to be cost-effective and eco-friendly. 相似文献
A comparative performance evaluation of DNA extraction methods from anti-diabetic botanical supplements using various commercial kits was conducted, to determine which produces the best quality DNA suitable for PCR amplification, sequencing and species identification. All plant materials involved were of suboptimal quality showing various levels of degradation and therefore representing real conditions for testing herbal supplements. Eight different DNA extraction methods were used to isolate genomic DNA from 13 medicinal plant products. Two methods for evaluation, DNA concentration measurements that included absorbance ratios as well as PCR amplifiability, were used to determine quantity and quality of extracted DNA. We found that neither DNA concentrations nor commonly used UV absorbance ratio measurements at A260/A280 between 1.7 and 1.9 are suitable for globally predicting PCR success in these plant samples, and that PCR amplifiablity itself was the best indicator of extracted product quality. However, our results suggest that A260/A280 ratios below about 1.3 and above 2.3 indicated a DNA quality too poor to amplify. Therefore, A260/A280 measurements are not useful to identify samples that likely will amplify but can be used to exclude samples that likely will not amplify reducing the cost for unnecessarily subjecting samples to PCR. The two Nucleospin® plant II kit extraction methods produced the most pure and amplifiable genomic DNA extracts. Our results suggest that there are clear, discernable differences between extraction methods for low quality plant samples in terms of producing contamination-free, high-quality genomic DNA to be used for further analysis. 相似文献
Abstract In the search for inhibitors of HIV integrase, the enzyme involved in the integration of viral DNA into host DNA, we have synthesized and studied a number of analogs of the heterocyclic molecule, chloroquine. 相似文献