培养基灭菌方式对细菌分离效率的影响

自然界蕴含大量未/难培养微生物,分离这些微生物对理论研究和资源开发具有重要意义。本研究使用高压灭菌和过滤除菌方式制备培养基,采用稀释涂布方法,从红树林灰泥样品中分离获得123株细菌,通过16S rRNA基因序列分析对其进行鉴定,进而探究培养基灭菌方式对细菌分离效果的影响。结果表明：过滤除菌培养基生长的单菌落数目（339±82）个显著多于高压灭菌培养基生长的单菌落数目（179±65）个;两种培养基分离细菌的群落结构在门、科和属分类水平上总体相似,但优势类群的数目和少数类群存在差异;过滤除菌培养基分离细菌的Shannon Wiener’s指数、均匀度、新种率、基因多样性均高于高压灭菌培养基,而其与近缘模式菌株相似度的平均值和中位数则低于高压灭菌培养基。因此,过滤除菌培养基分离获得细菌的多样性、均匀性和新颖性均高于高压灭菌培养基。本研究首次探究培养基灭菌方式对细菌分离效果的影响,具有更高分离效率的过滤除菌培养基为未/难培养微生物菌株资源获取提供了借鉴。     

Enantioselective Degradation of (2RS, 3RS)‐Paclobutrazol in Rat Liver Microsomes

Paclobutrazol, with two stereogenic centers, but gives only (2R, 3R) and (2S, 3S)‐enantiomers because of steric‐hindrance effects, is an important plant growth regulator in agriculture and horticulture. Enantioselective degradation of paclobutrazol was investigated in rat liver microsomes in vitro. The degradation kinetics and the enantiomer fraction were determined using a Lux Cellulose‐1 chiral column on a reverse‐phase liquid chromatography–tandem mass spectrometry system. The t_1/2 of (2R, 3R)‐paclobutrazol is 18.60 min, while the t_1/2 of (2S, 3S)‐paclobutrazol is 10.93 min. Such consequences clearly indicated that the degradation of paclobutrazol in rat liver microsomes was stereoselective and the degradation rate of (2S, 3S)‐paclobutrazol was much faster than (2R, 3R)‐paclobutrazol. In addition, significant differences between the two enantiomers were also observed in enzyme kinetic parameters. The V_max of (2S, 3S)‐paclobutrazol was more than 2‐fold of (2R, 3R)‐paclobutrazol and the Cl_int of (2S, 3S)‐paclobutrazol was higher than that of (2R, 3R)‐paclobutrazol after incubation in rat liver microsomes. These results may have potential implications for better environmental and ecological risk assessment for paclobutrazol. Chirality 27:344–348, 2015. © 2015 Wiley Periodicals, Inc.     

Correlation of genomic and expression alterations of AS3 with esophageal squamous cell carcinoma

Androgen-induced proliferation shutoff gene AS3, also known as APRIN, is a growth inhibitory gene that is in itially implicated inprostate cancer. This gene is required for androgen-dependent growth arrest and is a primary target for 1,25(OH)2D3 and androgens. Alle-lic loss at AS3 locus has been linked to a variety of cancers. However, the correlation of genomic and expression alterations of AS3 with esophageal squamous cell carcinoma (ESCC) is not well established. In this study, the genomic and expression alterations of AS3 in ESCC and their clinical significance are evaluated. Loss of beterozygosity (LOH) analysis using an AS3 intragenic mierosatellite marker D13S171 revealed 72% allelic loss at AS3 locus in ESCC, which is significantly correlated with higher pathological grade (P=0.042).RT-PCR examination showed that AS3 mRNA obviously decreased in 44% tumors and its down-regulation was correlated with the sex of patients (P=0.03). Furthermore, the correlation between genomic and expression alterations of AS3 gene was analyzed in 18 ESCC specimens, which indicated that the consistency between allelic loss and decreased mRNA expression of AS3 was relatively poor. The results of this study indicate that the aberrant expression of AS3 may be involved in the tumorigenesis of esophagus and is responsible for the male predominance of ESCC.     

折翼蝠冬眠期几项生理常数的测定及分析

折翼蝠(Miniopterus schreibersii chinensis Thomas)在皖南地区数量较多、分布较广,是哺乳类中具冬眠习性的异温动物。这种异温动物的生理生态研究,国内极少报道。我们于1981年10月至1982年5月对折翼蝠冬眠期的几项生理常数做了测定和分析,目的在于了解它们在冬眠期间的生理变化及其与外界环境因子之间的相互关系,从而进一步探讨异温动物冬眠期的代谢规律,为休眠的理论和动物资源的利用提供一点参考资料。     

Prognostic value of IL-27 polymorphisms and the susceptibility to epithelial ovarian cancer in a Chinese population

This study investigated the association between IL-27 gene polymorphisms and susceptibility to epithelial ovarian cancer in a Chinese population and discusses the risk factors associated with survival time. We collected data on 229 patients diagnosed with epithelial ovarian cancer, from 15 to 77 years of age with a long clinical follow-up period. Polymerase chain reaction-restriction fragment length polymorphism was performed to determine the genotype of IL-27 gene polymorphisms. Ovarian cancer-specific survival (OCSS) according to genotype of IL-27 gene polymorphisms was explored by Kaplan–Meier analysis and Cox proportional hazards modeling. Significant differences for genotype frequencies of both SNP sites were found between cases and controls. Both allele G frequencies were significantly greater among the cases (rs153109: 0.404 vs. 0.303, P = 0.001, odds ratio [OR]?=?1.333, 95% confidence interval [CI]?=?1.133–1.567; rs17855750: 0.146 vs. 0.083, P = 0.001, OR?=?1.766, 95% CI?=?1.258–2.481). Haplotype analysis showed haplotypes AG, GT and GG were associated with increased ovarian cancer susceptibility while AT was a protective haplotype. Advanced FIGO stage (stages III?+?IV) and non-optimal cytoreductive surgery (residual tumor ≥1 cm) were poor prognostic factors in the univariate analysis (P = 0.003, P = 0.049). However, FIGO stage was found to be the only independent significant prognostic factor by Cox proportional hazards analysis (P = 0.042). IL-27p28 mRNA expression was significantly decreased in ovarian cancer patients (P?<?0.0001), while no significant relationship was found between IL-27p28 mRNA expression and polymorphism of rs153109 and rs17855750 (P?=?0.193 and P?=?0.146, respectively). Our study suggests that IL-27 gene polymorphisms may be involved in the susceptibility to epithelial ovarian cancer, but not in survival in a clinic-based Chinese population. Haplotype analysis of these two SNPs seems to be an important mark to predict the disease susceptibility. Advanced FIGO stage, as the only significant, independent risk factor, predicts poor clinical outcomes for patients diagnosed with epithelial ovarian cancer. The decreased expression of IL-27p28 mRNA in ovarian cancer might indicate the antitumor activities of this novel cytokine.     

粤蓝链霉菌榴菌素生物合成基因orf20的功能

【目的】在大肠杆菌中,转录因子SoxR作为胞内氧化还原感应器,参与抗氧化胁迫的全局性调控。粤蓝链霉菌榴菌素生物合成基因簇内存在一个类soxR基因orf20,但其生理功能仍不清楚。【方法】将orf20基因在大肠杆菌中进行表达,分析携带重组质粒的大肠杆菌对百草枯抗性的变化。同时通过修改后的PCR-targeting方法构建粤蓝链霉菌orf20删除的突变株,分析突变株的表型变化和对百草枯抗性水平的变化。【结果】重组ORF20在羧基端含有组氨酸标签,并在大肠杆菌中获得可溶性表达,携带重组质粒pET28b-orf20的大肠杆菌对百草枯的抗性水平显著提高。粤蓝链霉菌orf20删除突变株仍具有产孢能力,生长特性没有改变,对百草枯的抗性水平也没有变化,但榴菌素的产量大幅提高,是野生株的3.3倍。【结论】在大肠杆菌中,orf20基因的编码产物能够被百草枯激活,替代SoxR参与抗氧化胁迫的调控。在粤蓝链霉菌中,orf20基因不参与抗氧化胁迫,而对榴菌素的产生有负调控效应。