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.     

肾素-血管紧张素系统在调节肾脏活动和慢性肾功能不全中的作用

一、肾内RAS的组成、生物学特征及肾内分布;(一)有关RAS的研究进展;(二)肾脏组织局部的RAS;(三)AngⅡ受体的亚型及其在肾内的分布;二、AngⅡ对肾脏血流动力学的影响;三、AngⅡ对肾脏的非血流动力学效应;(一)AngⅡ的促生长作用及促纤维生成效应;(二)AngⅡ作为促炎症因子的作用;四、有关RAS在肾功能不全中的临床研究     

Inhibition of adenylate cyclase by transglutaminase-catalyzed reactions in pigeon erythrocyte ghosts

We report the occurrence in pigeon erythrocytes of a soluble Ca2+-dependent transglutaminase (TGase) activity. The effect of the erythrocyte ghost protein modifications, determined by TGase-catalyzed reactions, on adenylate cyclase, phospholipid methyltransferase I and II activities and on the lipidic matrix fluidity of the membrane was investigated by using a purified guinea pig liver TGase preparation. The results showed a significant inhibitory effect of such modifications both on the basal and on the variously stimulated (by NaF, Gpp(NH)p alone or in the presence of 1-isoproterenol) adenylate cyclase activity. By contrast, both the phospholipid methylation and the fluidity of the lipidic matrix of the membrane were unaffected by TGase-mediated reactions. These data suggest a new possible inhibitory mechanism of the cyclic AMP synthesis which might be triggered by the enhancement of the cytosolic Ca2+ concentration.     

贵州六盘水发现东阳江麝鼩

在贵州省六盘水市杨梅乡慕尼克村,利用陷阱法捕捉到3号麝鼩属(Crocidura)标本。本次采集标本的体形较小,头体长(49.0 ± 0.8)mm,尾长[(41.8 ± 4.2)mm]略短于头体长(尾长/头体长为85%)。背毛呈浅灰褐色,腹毛颜色浅于背毛,呈灰色。尾部双色,背侧黑褐色,腹侧淡于背侧。前足背部白色,后足则为淡灰色。尾近乎裸露,尾基约1/3着生稀疏白色长毛。颅全长(15.92 ± 0.55)mm,脑颅高(4.75 ± 0.18)mm。上门齿1枚,有一长而大的前尖和一小而矮的后尖。上单尖齿3枚,第1单尖齿最大,第2单尖齿略大于第3单尖齿,1枚第四前臼齿(P4),3枚臼齿。上述特征与东阳江麝鼩(C. dongyangjiangensis)模式标本的描述和鉴定特征基本一致,因此将3号采集标本鉴定为东阳江麝鼩。基于Cyt b基因进行分子系统发育分析,采集标本与麝鼩属物种中的东阳江麝鼩遗传距离最近,在0.004 ~ 0.027之间。系统发生树显示,3号标本与东阳江麝鼩构成一个单系进化分支,进一步证实本次采集的3号标本是东阳江麝鼩,为贵州省分布新记录种。     

纤维蛋白溶酶原相关生长因子家族的结构与功能

ＨＧＦ作为对肝细胞具有刺激作用的因子,已为人广泛认识。近几年有关ＨＧＦ结构－功能相互关系方面的研究结果以及与其组成,结构均相似的ＭＳＰ的发生,将视线引向与此相关的一类蛋白－纤溶酶原相关生长因子家族。ＭＳＰ的出现以及ＭＳＰ和ＨＧＦ结构与功能的特性,使得人们不再单纯地研究某一因子／蛋白的结构和功能,而更关注结构与功能间的相互关系、结构作为进化结果的意义,更重要的是在此基础上实现对相关因子／蛋白的功能预     

A sensitive signal-on assay for MTase activity based on methylation-responsive hairpin-capture DNA probe

This work develops a simple, sensitive and signal-on electrochemical sensor for methyltransferase (MTase) activity analysis. The sensor is composed of a methylene blue-modi?ed "signaling DNA probe" and a "capture DNA probe" tethered methylation-responsive hairpin DNA (hairpin-capture DNA probe). The thiol- modified hairpin-capture DNA probe at 5' end was firstly self-assembled on gold electrode via Au-S bonding. Methylation-induced scission of hairpin-capture DNA probe would displace the hairpin section and remain the "capture DNA probe" section on the gold electrode. Subsequently, the remained "capture DNA probe" on the gold electrode can hybridize with the methylene blue-modi?ed "signaling DNA probe", mediating methylene blue onto the gold electrode surface to generate redox current. It was eT on state. The developed facile signal-on electrochemical sensing system showed a linear response to concentration of Dam MTase range from 0.1 to 1.0 U/mL. The detection limit of Dam MTase activity was determined to be 0.07 U/mL and the total detection time is 7h. The sensor also has the ability to provide information about the dynamics of methylation process. Furthermore, we demonstrated that this sensor could be utilized to screen inhibitors or drugs for Dam MTase.     

A new method for the determination of critical polyethylene glycol concentration for selective precipitation of DNA fragments

Separation strategies based on size-selective precipitation of DNA fragments with polyethylene glycol (PEG) have been used for achieving desired DNA interval in automated sample preparation for next-generation sequencing. By varying PEG concentration, DNA fragments of different sizes can be precipitated onto surfaces of carboxyl-coated paramagnetic particles selectively, and therefore, the desired DNA interval can be obtained. However, one of the crucial points in this approach is to determine the critical PEG concentration for DNA fragment of a certain size. The aim of this work was to develop a convenient and reliable method for accurately determining the critical PEG concentration. In our method, at a fixed concentration of sodium chloride (NaCl), recovered DNA samples obtained with different PEG concentrations were directly quantified, and their concentrations as a function of the PEG concentration were fitted by the logistic function. The critical PEG value was easily and accurately determined from the fitted logistic function. The repeatability and stability of the critical PEG value were assessed, showing an excellent reliability of the method. Based on this method, critical PEG values of different-size DNA fragments were determined at different NaCl concentrations. The effectiveness of the method was also demonstrated by selective precipitation of DNA fragments.     

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。     

昆虫保幼激素促进家蚕杆状病毒系统的基因表达

杆状病毒表达载体系统(Baculovirus Expression VecterSvstem,BEVS)的一个最大优点是外源基因的高效表达(Hy-perexpression).但是,不同的外源基因在BEVS系统中的表达水平相差很大,较低的如α-干扰素,表达量为1～5mg/L培养细胞;高的如β-半乳糖苷酶,表达量可达600mg/L培养细胞.外源基因在BEVS系统中表达量受到诸多因素的影响,如细胞的类型与质量,外源基因蛋白的性质,启动子序列的完整性,是否为融合蛋白等[1].如何使外源基因在BEVS系统中高效表达,是近年来该领域中研究最活跃的方向之一.已证实家蚕杆状病毒的表达量受宿主遗传型的影响,最低和最高的遗传型相差达7倍以上[2].林水中等发现家蚕饲料中添食适当浓度的硫酸铜可提高外源基因单位表达量10%左右[3].杆状病毒在复制循环中表现出两种类型:芽生病毒和包涵体病毒,其中芽生病毒引起宿主体内不同组织间的感染,包涵体病毒则引起宿主之间感染[1].杆状病毒基因组中蜕皮激素尿苷二磷酸葡萄糖基转移酶(egt)基因影响激素在宿主体内的平衡[4],egt基因通过糖基化作用使蜕皮激素失活,打破宿主体内的激素平衡,延长幼虫期,以利于病毒的增殖[5].家蚕血淋巴中保幼激素(Juvenile hormone,JH)的滴度同样决定着幼虫发育的进程[6],本文通过体表使用保幼激素,以研究保幼激素对家蚕核型多角体病毒和宿主之间的相互关系及对外源基因表达量的影响.