A green and effective method for the determination of metalaxyl enantiomers in tobacco and soil by supercritical fluid chromatography–tandem mass spectrometry

We reported a new methodology for the stereoselective determination of metalaxyl enantiomers in tobacco and soil. The QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was used for the extraction and clean-up of the tobacco and soil samples. Separation of the metalaxyl enantiomers was performed on an ACQUITY UPC2 Trefoil CEL1 chiral column coupled with supercritical fluid chromatography with tandem mass spectrometry (SFC-MS/MS), and the run time was only 5 minutes. Under the optimized conditions, the recoveries for the enantiomers were between 78.2% and 93.3% with intraday relative standard deviations (RSDs) ranging from 1.1% to 5.4%. The limit of detection (LOD) for the enantiomers in tobacco and soil varied from 0.005 to 0.007 mg/kg, and the limit of quantitation (LOQ) ranged from 0.017 to 0.020 mg/kg. In this method, only a small amount of methanol was consumed to obtain a rapid stereoselective separation. This proposed method showed good accuracy and precision and might be suitable for fast enantioselective determination of metalaxyl in food and environmental samples. The developed method was further validated by application to the analysis of authentic samples.     

基于近红外漫反射光谱快速测定淫羊藿蛋白质含量

采用近红外漫反射光谱技术对淫羊藿(Epimedium)的蛋白质含量进行快速且无损检测。近红外漫反射光谱经二阶导数处理、标准多元离散校正及主成分分析聚类处理后, 采用改进最小二乘法回归得到的定标模型预测效果最佳, 定标决定系数、交互验证标准差及交互验证相关系数分别为0.923、0.554和0.717。近红外光谱分析法的测定结果与用凯氏定氮法所得结果无显著差异, 两种方法测定值的相关性较高(R²=0.933 9)。重复性实验表明, 近红外光谱分析法的相对标准偏差为0.937%。该研究首次采用近红外光谱分析法测定了8种淫羊藿的蛋白质含量。该方法简便、精确, 在淫羊藿资源开发利用和药材质量控制方面具有参考意义。     

Detection and Quantification of Fusarium oxysporum f. sp. niveum Race 1 in Plants and Soil by Real-time PCR

Fusarium wilt caused by Fusarium oxysporum f. sp. niveum (Fon) is the most serious soil-borne disease in the world and has become the main limiting factor of watermelon production. Reliable and quick detection and quantification of Fon are essential in the early stages of infection for control of watermelon Fusarium wilt. Traditional detection and identification tests are laborious and cannot efficiently quantify Fon isolates. In this work, a real-time polymerase chain reaction (PCR) assay has been described to accurately identify and quantify Fon in watermelon plants and soil. The FONRT-18 specific primer set which was designed based on identified specific sequence amplified a specific 172 bp band from Fon and no amplification from the other formae speciales of Fusarium oxysporum tested. The detection limits with primers were 1.26 pg/μl genomic DNA of Fon, 0.2 pg/ng total plant DNA in inoculated plant, and 50 conidia/g soil. The PCR assay could also evaluate the relationships between the disease index and Fon DNA quantity in watermelon plants and soil. The assay was further used to estimate the Fon content in soil after disinfection with CaCN₂. The real-time PCR method is rapid, accurate and reliable for monitoring and quantification analysis of Fon in watermelon plants and soil. It can be applied to the study of disease diagnosis, plant-pathogen interactions, and effective management.     

内皮素—1预处理大鼠心脏Gaq／11和Gia蛋白含量的变化

The present study was undertaken to explore the mechanism of G protein-mediated signal transduction pathway during endothelin-1 (ET-1) pre-treatment and ischemic preconditioning (IP). Rats were divided into four groups: ET-1, IP, ischaemia-reperfusion (IR) and control groups. ET-1 pre-treatment model was prepared by administrating 0.5 nmol/(L.kg) ET-1 into rat left ventricle, whereas IP model was prepared by ligating the left coronary artery for 5 min followed by 30 min reperfusion. All the animals were subjected to 60 min regional ischaemia and 30 min reperfusion alternately and then parameters of ventricular arrhythmia and expression of cardiac Galphaq/11 and Gialpha2 were measured. The results showed that the scores of ventricular arrhythmia decreased significantly in both ET-1 and IP treated groups as compared with IR group. In comparison with control group, Galphaq/11 increased by 77.8% (P<0.05) and 110.6% (P<0.01) in IP and ET-1 group respectively. Gialpha2 showed no significant difference in IP group, while it decreased by 31.0% (P<0.01) in ET-1 group. In conclusion, activation of G alphaq/11 may be related to the protecting mechanism of ET-1 pre-treatment and IP, whereas Gialpha2 may only play a role in ET-1 pre-treatment.     

Determination of genetic relationships among five indigenous Chinese goat breeds with six microsatellite markers

Microsatellite variation was analyzed in five Chinese indigenous goat breeds, which include four Cashmere breeds (Tibetan, Neimonggol, Liaoning, Taihang) and one Hubei local breed (Matou) used for meat production. Five ovine and one bovine microsatellites, selected from eight ovine microsatellites and five bovine microsatellites were suitable for use in this study. With these six microsatellites, allele frequencies, heterozygosity, polymorphism information content (PIC) and effective allele number were calculated. A neighbor-joining tree was constructed using Nei's standard genetic distance (1978). In the tree, Neimonggol and Liaoning were grouped together, then with Taihang; while Tibetan and Matou individually had their own branch. The genetic relationship of five breeds corresponds to their history and geographic origins.     

用鱼血清转氨酶监测水污染的研究

以三硝基甲苯(INT)、六六六、滴滴涕(DDT)、对硫磷(E-605)、氯化汞分别进行白鲢鱼种的急性致毒实验,与对照组相比,鱼血清谷草转氨酶活性显著增加;对硫磷还引起血清谷丙转氨酶活性的升高。血清转氨酶活性增加的程度与氯化汞浓度相关。不同种类的我国淡水鲤科鱼类、不同鱼龄、不同水体以及短期饥饿、惊扰及网箱饲养对血清转氨酶活性没有影响,但水温升高或溶氧低于1ppm会使鱼血清谷草转氨酶活性升高。水温与鱼血清谷草转氨酶活性有相关性。       

NIRF, a novel ubiquitin ligase, interacts with hepatitis B virus core protein and promotes its degradation

Hepatitis B virus (HBV) core protein (HBc) is a major component of viral nucleocapsid and a multifunctional protein involved in viral maturation and release. It is unstable and present in cells at low level because of K96 lysine residue, which is a ubiquitin acceptor site. Np95/ICBP90-like RING finger protein (NIRF) has auto-ubiquitination activity which is the hallmark of a ubiquitin ligase. In the present study, ubiquitin ligase, NIRF, binds to HBc and leads to the proteasome-mediated degradation of HBc in vivo. NIRF down-regulates HBc protein level, resulting in the decrease of the amount of HBV particles in supernatant of HepG2.2.15 cells. However knockdown of NIRF significantly increases endogenous HBc protein level, leading to HBV release. The results reveal that NIRF interacts with HBc and promotes the degradation of HBc in vivo. The pathway of NIRF-mediated ubiquitin–proteasome affects the release of HBV particles by controlling the amounts of HBc. It indicates that NIRF may participate in the maturation of HBV.     

重寄生真菌盾壳霉pH信号通路中Pal相关基因的功能鉴定

【目的】研究pH信号通路(Pal)在重寄生真菌盾壳霉与寄主核盘菌互作过程中的作用。【方法】从盾壳霉全基因组信息中分析获得了6个Pal相关基因CmpalA、CmpalB、CmpalC、CmpalF、CmpalH和CmpalI的全编码序列和氨基酸序列,通过PEG介导的原生质转化技术获得了CmpalA、CmpalB、CmpalC、CmpalF和CmpalH等5个基因的敲除突变体,分析这些敲除突变体与野生型在菌落培养性状、重寄生能力、降解草酸能力、产生抗真菌物质能力等方面的差异。【结果】与野生型相比,在pH 6–8的条件下,5个Pal相关基因敲除突变体的菌丝生长受到显著抑制,这说明缺失Pal相关基因使盾壳霉对高pH值环境更加敏感。菌核重寄生试验发现5个Pal相关基因敲除突变体的重寄生能力均显著低于野生型。qRT-PCR试验结果表明,敲除Pal相关基因之后导致重寄生相关酶基因Cmch1、Cmg1和Cmsp1的表达量显著降低,而且pH信号通路下游的CmpacC基因的表达量也显著降低。Pal相关基因敲除突变体在pH 6条件下对草酸盐的降解能力显著高于野生型,同时这5个突变体在pH 8条件下产生抗真菌物质能力也显著高于野生型。【结论】pH信号通路相关基因的缺失影响盾壳霉对环境pH的响应。pH信号通路在盾壳霉与核盘菌互作中发挥重要作用,不仅影响盾壳霉的重寄生作用,而且还影响盾壳霉的草酸降解作用和抗真菌作用。     

Secretases as therapeutic targets for Alzheimer's disease

Accumulation of amyloid-β (Aβ) is widely accepted as the key instigator of Alzheimer’s disease (AD). The proposed mechanism is that accumulation of Aβ results in inflammatory responses, oxidative damages, neurofibrillary tangles and, subsequently, neuronal/synaptic dysfunction and neuronal loss. Given the critical role of Aβ in the disease process, the proteases that produce this peptide are obvious targets. The goal would be to develop drugs that can inhibit the activity of these targets. Protease inhibitors have proved very effective for treating other disorders such as AIDS and hypertension. Mutations in APP (amyloid-β precursor protein), which flanks the Aβ sequence, cause early-onset familial AD, and evidence has pointed to the APP-to-Aβ conversion as a possible therapeutic target. Therapies aimed at modifying Aβ-related processes aim higher up the cascade and are therefore more likely to be able to alter the progression of the disease. However, it is not yet fully known whether the increases in Aβ levels are merely a result of earlier events that were already causing the disease.