<Emphasis Type="Italic">Actinopolyspora xinjiangensis</Emphasis> sp. nov., a novel exteremely halophilic actinomycete isolated from a salt lake in Xinjiang,China

A novel halophilic, filamentous actinobacterium, designated TRM 40136^T, was isolated from a hypersaline habitat in Xinjiang Province, north-west China. The strain is aerobic, Gram-positive, halophilic, and the optimum NaCl concentration for growth is 10–15% (w/v). The whole-cell sugar pattern consists of xylose, glucose and arabinose. The predominant menaquinone is MK-6 (51.2%) and the major fatty acids are anteiso-C15:0 (35.2%), anteiso-C17:0 (15.9%) and iso-C15:0 (13.7%). The phospholipid pattern consists of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine and two unknown phospholipids. The G + C content of the genomic DNA is 68.9 mol%. Phylogenetic analysis showed that strain TRM 40136^T had 16S rRNA gene sequence similarity of 96.1% with the closest described species Actinopolyspora mortivallis, and it can be distinguished from all species in the genus Actinopolyspora by using these data of polyphasic taxonomy study. On the basis of the polyphasic evidence, the strain TRM 40136^T should be designated as a novel species of the genus Actinopolyspora for which the name Actinopolyspora xinjiangensis sp.nov. is proposed. The type strain is TRM 40136^T (=CCTCC AA 209080^T = KCTC 19656^T).     

Determination of clindamycin in human plasma by liquid chromatography–electrospray tandem mass spectrometry: application to the bioequivalence study of clindamycin

A simple, sensitive and specific liquid chromatography–electrospray tandem mass spectrometry (LC–MS–MS) method for the determination of clindamycin (I) was developed. Both I and verapamil (II, internal standard) were analyzed using a C₁₈ column with a mobile phase of 80% acetonitrile–0.01% trifluoroacetic acid. Column eluents were monitored by electrospray tandem mass spectrometry. Multiple reaction monitoring (MRM) using the parent to daughter combinations of m/z 425→126 and 455→165 was used to quantitate I. A limit of quantitation of 0.0500 μg/ml was found. The assay exhibited a linear dynamic range of 0.0500–20.0 μg/ml and gave a correlation coefficient (r²) of 0.998 or better. The chromatographic run time was approximately 2 min. The intra-batch precision and accuracy of the quality controls (QCs, 0.0500, 0.150, 1.50, 15.0 and 20.0 μg/ml) were characterized by coefficients of variation (CVs) of 5.13 to 13.7% and relative errors (REs) of −4.34 to 4.58%, respectively. The inter-batch precision and accuracy of the QCs were characterized by CVs of 4.35 to 8.32% and REs of −10.8 to −4.17%, respectively. The method has successfully been applied to the analysis of samples taken up to 12 h after oral administration of 300 mg of I in healthy volunteers.     

Tunable Charge Transfer and Dual Plasmon Resonances of Au@WO3−x Hybrids and Applications in Photocatalytic Hydrogen Generation

Plasmonics - We synthesized Au@WO3−x hybrids with dual plasmon resonances in visible and near-infrared (NIR) regions induced by two counterparts for enhancing photocatalytic activity. Au...     

siRNA-mediated gene silencing of MexB from the MexA-MexB-OprM efflux pump in Pseudomonas aeruginosa

To gain insights into the effect of MexB gene under the short interfering RNA (siRNA), we synthesized 21 bp siRNA duplexes against the MexB gene. RT-PCR was performed to determine whether the siRNA inhibited the expression of MexB mRNA. Changes in antibiotic susceptibility in response to siRNA were measured by the E-test method. The efficacy of siRNAs was determined in a murine model of chronic P. aeruginosa lung infection. MexB-siRNAs inhibited both mRNA expression and the activity of P. aeruginosa in vitro. In vivo, siRNA was effective in reducing the bacterial load in the model of chronic lung infection and the P. aeruginosa-induced pathological changes. MexB-siRNA treatment enhanced the production of inflammatory cytokines in the early infection stage (P ＜ 0.05). Our results suggest that targeting of MexB with siRNA appears to be a novel strategy for treating P. aeruginosa infections. [BMB Reports 2014; 47(4): 203-208]