Differential response to paraquat induced oxidative stress in two rice cultivars on antioxidants and chlorophyll a fluorescence

The responses of antioxidative system and photosystem II photochemistry of rice (Oryza sativa L.) to paraquat induced oxidative stress were investigated in a chilling-tolerant cultivar Xiangnuo no. 1, and a chilling-susceptible cultivar, IR-50. Electrolyte leakage and malondialdehyde (MDA) content of Xiangnuo no. 1 were little affected by paraquat, but they increased in IR-50. After paraquat treatment, superoxide dismutase (SOD) activity remained high in Xiangnuo no. 1, while it declined in IR-50. Activities of catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) declined with oxidative stress in both cultivars, but Xiangnuo no. 1 had higher GR activity than IR-50. Under paraquat induced oxidative stress, ascorbic acid (AsA) and reduced glutathione (GSH) concentrations remained high in Xiangnuo no. 1, but decreased in IR-50. The results indicated that higher activities of SOD and GR and higher contents of AsA and GSH in Xiangnuo no. 1 under paraquat induced oxidative stress were associated with its tolerance to paraquat, while paraquat induced damage to IR-50 was related to decreased activities of SOD, APX and GR and contents of AsA and GSH. F _v/F _m, Φ _PSII, and qP remained high in Xiangnuo no. 1, while they decreased greatly in IR-50 under paraquat induced oxidative stress.     

观察导管和筛管的两种简便方法

采用将徒手切片煮沸透明的方法改进了两种观察导管和筛管的方法     

Genetic consequences of group living in Mongolian gerbils

Social behavior can shape the local population genetic structure of mammals. Group living can increase pairwise genetic relatedness of mammals at a local level but differentiate the genetic structure at a population level through offspring philopatry and nonrandom mating. Our study aimed to test the hypothesis that social groups of Mongolian gerbils (Meriones unguiculatus) would consist of genetically related individuals due to offspring philopatry and would have distinct genetic structures because of restricted gene flow among social groups and nonrandom mating. We genotyped 327 wild gerbils, live captured from 28 social groups in Inner Mongolia, China, using nine microsatellite loci. The within-group pairwise genetic relatedness coefficient averaged 0.28 ± 0.14 (standard deviation), whereas the average pairwise genetic relatedness coefficient of the whole gerbil population was 0.0 ± 0.2. Additionally, the value of the global F statistic (F(st)) was 0.21, suggesting a substantial genetic differentiation among social groups of Mongolian gerbils. The Bayesian clustering divided the 327 gerbils into 23 distinct genetic clusters. Therefore, our results show that high within-group genetic relatedness and among-group genetic differentiation are the genetic consequences of group living in social mammals because of restricted gene flow, female philopatry, and nonrandom mating within social groups.     

miR‐10a restores human mesenchymal stem cell differentiation by repressing KLF4

miRNAs have recently been shown to play a significant role in human aging. However, data demonstrating the effects of aging‐related miRNAs in human mesenchymal stem cells (hMSCs) are limited. We observed that hMSC differentiation decreased with aging. We also identified that miR‐10a expression was significantly decreased with age by comparing the miRNA expression of hMSCs derived from young and aged individuals. Therefore, we hypothesized that the downregulation of miR‐10a may be associated with the decreased differentiation capability of hMSCs from aged individuals. Lentiviral constructs were used to up‐ or downregulate miR‐10a in young and old hMSCs. Upregulation of miR‐10a resulted in increased differentiation to adipogenic, osteogenic, and chondrogenic lineages and in reduced cell senescence. Conversely, downregulation of miR‐10a resulted in decreased cell differentiation and increased cell senescence. A chimeric luciferase reporter system was generated, tagged with the full‐length 3′‐UTR region of KLF4 harboring the seed‐matched sequence with or without four nucleotide mutations. These constructs were cotransfected with the miR‐10a mimic into cells. The luciferase activity was significantly repressed by the miR‐10a mimic, proving the direct binding of miR‐10a to the 3′‐UTR of KLF4. Direct suppression of KLF4 in aged hMSCs increased cell differentiation and decreased cell senescence. In conclusion, miR‐10a restores the differentiation capability of aged hMSCs through repression of KLF4. Aging‐related miRNAs may have broad applications in the restoration of cell dysfunction caused by aging. J. Cell. Physiol. 228: 2324–2336, 2013. © The Authors. Published by Wiley Periodicals, Inc.     

A Segment of 97 Amino Acids within the Translocation Domain of Clostridium difficile Toxin B Is Essential for Toxicity

Clostridium difficile toxin B (TcdB) intoxicates target cells by glucosylating Rho GTPases. TcdB (269 kDa) consists of at least 4 functional domains including a glucosyltransferase domain (GTD), a cysteine protease domain (CPD), a translocation domain (TD), and a receptor binding domain (RBD). The function and molecular mode of action of the TD, which is the largest segment of TcdB and comprises nearly 50% of the protein, remain largely unknown. Here we show that a 97-amino-acid segment (AA1756 – 1852, designated as ?97 or D97), located in the C-terminus of the TD and adjacent to the RBD, is essential for the cellular activity of TcdB. Deletion of this segment in TcdB (designated as TxB-D97), did not adversely alter toxin enzymatic activities or its cellular binding and uptake capacity. TxB-D97 bound to and entered cells in a manner similar to TcdB holotoxin. Both wild type and mutant toxins released their GTDs similarly in the presence of inositol hexakisphosphate (InsP₆), and showed a similar glucosyltransferase activity in a cell-free glucosylating assay. Despite these similarities, the cytotoxic activity of TxB-D97 was reduced by more than 5 logs compared to wild type toxin, supported by the inability of TxB-D97 to glucosylate Rac1 of target cells. Moreover, the mutant toxin failed to elicit tumor necrosis factor alpha (TNF-α) in macrophages, a process dependent on the glucosyltransferase activity of the toxin. Cellular fractionation of toxin-exposed cells revealed that TxB-D97 was unable to efficiently release the GTD into cytosol. Thereby, we conclude the 97-amino-acid region of the TD C-terminus of TcdB adjacent to the RBD, is essential for the toxicity of TcdB.     

四种提取芸芥基因组DNA方法的比较

以芸芥为材料 ,分别用CTAB法、SDS法、尿素法、NaOH法四种方法对芸芥基因组DNA进行了提取 ;并用紫外光分光光度计法、琼脂糖电泳法和RAPD分析法对所提取的DNA进行检测 ,将它们在DNA的产量、质量和耗时、耗费等方面的优缺点进行比较 ,以便在实际工作中根据不同的试验条件选取最合适的提取方法。通过四种方法的比较 ,研究认为尿素法是芸芥基因组DNA的最佳提取方法。     

Determination of cefaclor in human plasma by a sensitive and specific liquid chromatographic-tandem mass spectrometric method

A sensitive and specific liquid chromatographic-tandem mass spectrometric method is described for the determination of cefaclor in human plasma. The plasma samples were treated by two sample preparation procedures, i.e. protein precipitation (PPT) and solid-phase extraction (SPE). The pretreated samples were analyzed on a C(18) HPLC column interfaced with a triple quadrupole tandem mass spectrometer. Positive electrospray ionization (ESI) was employed as the ionization source. The analyte and internal standard ampicillin (for PPT) or cefetamet (for SPE) were detected by use of selected reaction monitoring (SRM) mode. The lower limit of quantitation obtained as a result of the PPT procedure was 100 ng/ml. The intra- and inter-run precision, calculated from quality control (QC) samples was less than 12% for cefaclor. The accuracy as determined from QC samples was within +/-3% for the analyte. The SPE procedure could provide the lower limit of quantitation of 2 ng/ml. The precision and accuracy were measured to be below 7.1% and between -3.6% and 1.1%, respectively, for all QC samples. The method was applied for the evaluation of the pharmacokinetic profiles of cefaclor sustained-release formulation.     

MicroRNA-30c serves as an independent biochemical recurrence predictor and potential tumor suppressor for prostate cancer

MicroRNA-30c (miR-30c) acts as a tumor suppressor or a tumor promoter in various human malignancies. However, the involvement of miR-30c in prostate cancer (PCa) is still unclear. The aim of this study was to investigate the molecular function and the clinical significance of miR-30c in PCa. Expression levels of miR-30c in PCa tissues and cells were detected by quantitative real-time-PCR (qRT-PCR). Additionally, the associations of miR-30c expression with clinicopathological features and prognosis in PCa patients were analyzed. The potential role of miR-30c in tumorigenesis of PCa cells was further evaluated by in vitro cell assays. MiR-30c was significantly down-regulated in PCa tissues and cells compared with the corresponding controls (P < 0.05). In addition, the downregulation of miR-30c in PCa tissues was significantly associated with higher Gleason score (P = 0.009), advanced pathological stage (P = 0.016) and biochemical recurrence (P = 0.034). Moreover, Kaplan–Meier survival analysis showed that the reduced expression of miR-30c was correlated with shorter biochemical recurrence-free survival (P = 0.023). The multivariate analysis also identified miR-30c as an independent prognostic predictor for biochemical recurrence-free survival in patients with PCa. Furthermore, the enforced expression of miR-30c suppressed proliferation, migration and invasion of PCa cells in vitro. Our data indicated the involvement of miR-30c in PCa progression and suggested its potential role as an independent predictor of biochemical recurrence in PCa. On cellular level, miR-30c may function as a tumor suppressor for PCa cells by inhibiting tumor cell proliferation, migration and invasion.     

Endoscopic Biopsy in Gastrointestinal Neuroendocrine Neoplasms: A Retrospective Study

Background

Gastrointestinal neuroendocrine neoplasms (GI-NENs) are often located in the deep mucosa or submucosa, and the efficacy of endoscopic biopsy for diagnosis and treatment of GI-NENs is not fully understood.

Objective

The current study analyzed GI-NENs, especially those diagnosed pathologically and resected endoscopically, and focused on the biopsy and cold biopsy forceps polypectomy (CBP) to analyze their roles in diagnosing and treating GI-NENs.

Methods

Clinical data of all GI-NENs were reviewed from January 2006 to March 2012. Histopathology was used to diagnose GI-NENs, which were confirmed by immunohistochemistry.

Results

67.96% GI-NENs were diagnosed pathologically by endoscopy. Only 26.21% were diagnosed pathologically by biopsies before treatment. The diagnostic rate was significantly higher in polypoid (76.47%) and submucosal lesions (68.75%), than in ulcerative lesions (12.00%). However, biopsies were only taken in 56.31% patients, including 51.52% of polypoid lesions, 35.56% of submucosal lesions and 100.00% of ulcerative lesions. Endoscopic resection removed 61.76% of GI-NENs, including six by CBP, 14 by snare polypectomy with electrocauterization, 28 by endoscopic mucosal resection (EMR) and 15 by endoscopic submucosal dissection (ESD). 51.52% polypoid GI-NENs had infiltrated the submucosa under microscopic examination. CBP had a significantly higher rate of remnant (33.33%) than snare polypectomy with electrocauterization, EMR and ESD (all 0.00%).

Conclusions

Biopsies for all polypoid and submucosal lesions will improve pre-operative diagnosis. The high rate of submucosal infiltration of polypoid GI-NENs determined that CBP was inadequate in the treatment of GI-NENs. Diminutive polypoid GI-NENs that disappeared after CBP had a high risk of remnant and should be closely followed up over the long term.