Cofilin promotes actin polymerization and defines the direction of cell motility

A general caging method for proteins that are regulated by phosphorylation was used to study the in vivo biochemical action of cofilin and the subsequent cellular response. By acute and local activation of a chemically engineered, light-sensitive phosphocofilin mimic, we demonstrate that cofilin polymerizes actin, generates protrusions, and determines the direction of cell migration. We propose a role for cofilin that is distinct from its role as an actin-depolymerizing factor.     

Local actin polymerization and dynamin recruitment in SV40-induced internalization of caveolae

Simian virus 40 (SV40) utilizes endocytosis through caveolae for infectious entry into host cells. We found that after binding to caveolae, virus particles induced transient breakdown of actin stress fibers. Actin was then recruited to virus-loaded caveolae as actin patches that served as sites for actin "tail" formation. Dynamin II was also transiently recruited. These events depended on the presence of cholesterol and on the activation of tyrosine kinases that phosphorylated proteins in caveolae. They were necessary for formation of caveolae-derived endocytic vesicles and for infection of the cell. Thus, caveolar endocytosis is ligand-triggered and involves extensive rearrangement of the actin cytoskeleton.     

氟吡菌胺及其代谢物在黄瓜中的残留

为评价氟吡菌胺及其代谢物在黄瓜上的安全性,建立了同时检测氟吡菌胺及其代谢物2,6-二氯苯甲酰胺的高效液相色谱-串联质谱法。前处理采用以乙腈提取,无水硫酸镁、石墨化碳（GCB）和乙二胺-N-丙基硅烷（PSA）为分散净化剂的QuEChERS方法,应用高效液相色谱-串联质谱仪在多反应监测（MRM）模式下进行检测。结果表明,在0.05~5 mg·kg^-1的加标范围内,氟吡菌胺和2,6-二氯苯甲酰胺的平均回收率分别为82%~98%和90%~100%,相对标准偏差（RSD,n=5）分别为1.6%~7.9%和3.2%~9.4%,定量检出限（LOQ）为0.05 mg·kg^-1。最终残留试验表明：在氟吡菌胺推荐剂量（735 g·hm^-2）下,施药3次,距最后一次施药间隔1、3 d和5 d时采收,氟吡菌胺及2,6-二氯苯甲酰胺在黄瓜上的最高残留量均小于0.05 mg·kg^-1,低于我国规定的氟吡菌胺在黄瓜中的最大残留限量0.5 mg·kg^-1。该方法前处理过程简单、方便、快速,灵敏度、准确度和精密度均满足残留分析的要求,可用于氟吡菌胺及代谢物2,6-二氯苯甲酰胺在黄瓜中的残留检测。     

豌豆肌动蛋白异型体PEAc3的原核表达及其聚合特性分析

植物肌动蛋白在植物顶端生长、细胞分裂分化和细胞信号转导等多种生命活动中发挥着重要作用.豌豆中存在多种肌动蛋白异型体.研究豌豆肌动蛋白异型体PEAc3与组氨酸标签(His-tag)及绿色荧光蛋白(GFP)的融合表达,并分析了融合蛋白的聚合特性.采用RT-PCR的方法克隆PEAc3基因,构建原核表达载体pET30a-His-PEAc3-GFP.用DNAman生物学软件分析表明,PEAc3融合蛋白全长675个氨基酸,分子量74.74 ku,等电点5.81.将pET30a-His-PEAc3-GFP转入大肠杆菌BL21中,优化的诱导表达条件为:25℃,当菌液OD600达到0.8时加入IPTG(浓度0.1 mmol/L),诱导表达4 h.采用尿素变性复性、镍柱亲和层析的方法从包涵体中纯化获得高纯度融合蛋白.融合蛋白His-PEAc3一GFP能够体外聚合,聚合临界浓度为0.5 μmol/L.单体His-PEAc3-GFP对DnaseⅠ有抑制作用,聚合后对肌球蛋白Mg-ATPase活性有一定的激活作用.上述结果表明,原核表达的His-PEAc3-GFP可能具有类似于一般肌动蛋白的聚合特性.     

桃中腈苯唑残留及其代谢产物的测定方法研究

腈苯唑(RH7592)是三唑类杀菌剂,在自然环境中有两种互为光学异构体的代谢产物RH99129和RH99130。本实验应用气相色谱法测定桃中残留腈苯唑及其代谢产物,结果表明:腈苯唑回收率86.6%~96.7%,RH99129回收率80.1%~94.4%,RH99130回收率80.1%~93.1%。本方法简单、定量准确,能够满足对桃中残留腈苯唑(RH7592)及其代谢产物的测定要求。     

高效液相色谱法检测黄瓜中涕灭威及其代谢物的残留量

建立了测定黄瓜中涕灭威及其代谢物残留量的高效液相色谱—荧光检测方法。样品经乙腈提取,固相萃取柱净化,用流动相溶解后,柱后衍生化,用高效液相色谱—荧光检测器在激发波长(ex)为339nm、发射波长(em)为445 nm处测定。结果在0.01~0.5 mg/kg添加水平,回收率为83.1%~89.6%,相对标准偏差为2.3%~4.9%,其检出限为0.005 mg/kg。     

杨梅中灭蝇胺及其代谢物检测方法与风险评估

杨梅是我国南方地区重要经济作物,因其登记农药种类少,裸果食用的质量安全问题备受关注.果蝇是杨梅果实成熟期最为重要的虫害,对于果蝇防治药剂的残留风险评估十分必要.生产调研中发现,灭蝇胺在生产中被用于防治果蝇,但灭蝇胺及其代谢产物三聚氰胺有较强的水溶性,为其检测方法的开发带来了困难.本研究采用固相萃取-高效液相串联质谱仪(...     

湖北贝母活性成分与内生菌次级代谢产物研究

为探究湖北贝母不同组织贝母素乙含量、内生菌组成及其次级代谢产物的抑菌活性,采用气相色谱法测定湖北贝母鳞茎、花、叶的贝母素乙含量,分别利用16S rDNA和ITS测序技术鉴定内生细菌和真菌,并通过琼脂扩散法、微量二倍稀释法研究内生菌次级代谢产物对10株供试菌的抑菌活性。结果表明:湖北贝母叶中贝母素乙含量最高,达(3.99±0.10) mg/g,其含量是鳞茎的1.78倍、花的4.24倍;从湖北贝母中分离鉴定了4株内生菌,分别为Pseudomonas sp. BM-X-6、Arthrinium sp. BM-Z-5、Aspergillus sp. BM-Z-1、Aspergillus sp. BM-Z-3;3株内生真菌次级代谢产物抑菌活性均优于细菌Pseudomonas sp. BM-X-6,其中Arthrinium sp. BM-Z-5的次级代谢产物抑菌谱最广,对肺炎克雷伯菌、金黄色葡萄球菌、藤黄微球菌、鲍曼不动杆菌、耐甲氧西林金黄色葡萄球菌有中度抑制活性。     

Pathogen effectors target Arabidopsis EDS1 and alter its interactions with immune regulators

Plant resistance proteins detect the presence of specific pathogen effectors and initiate effector-triggered immunity. Few immune regulators downstream of resistance proteins have been identified, none of which are known virulence targets of effectors. We show that Arabidopsis ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1), a positive regulator of basal resistance and of effector-triggered immunity specifically mediated by Toll-interleukin-1 receptor-nucleotide binding-leucine-rich repeat (TIR-NB-LRR) resistance proteins, forms protein complexes with the TIR-NB-LRR disease resistance proteins RPS4 and RPS6 and with the negative immune regulator SRFR1 at a cytoplasmic membrane. Further, the cognate bacterial effectors AvrRps4 and HopA1 disrupt these EDS1 complexes. Tight association of EDS1 with TIR-NB-LRR-mediated immunity may therefore derive mainly from being guarded by TIR-NB-LRR proteins, and activation of this branch of effector-triggered immunity may directly connect to the basal resistance signaling pathway via EDS1.     

丁氟螨酯及其代谢物对大型溞的毒性效应

为评价丁氟螨酯及其代谢物[A-2、AB-1 dimer、AB-1、AB-11、B-1、B-3、Target 1(B-2)、Met-1]对水生生物的生态风险,采用半静态法测定丁氟螨酯及其8种代谢物对大型溞48 h暴露的急性毒性效应,以及丁氟螨酯对大型溞的21 d慢性毒性效应.结果表明:丁氟螨酯、Target 1(B-2)...     

动物源性食品中呋喃唑酮及其代谢物的检测

简述了呋喃唑酮主要代谢物3-氨基-2-唑酮(AOZ)的稳定特性和致癌特性,介绍了动物源性食品中呋喃唑酮残留物原药分子和代谢物AOZ的检测技术,指出我国相关检测标准的不足,提出以检测代谢物来反映硝基呋喃类的真实残留量,并对今后我国呋喃唑酮的监管工作提出建议。     

Significance of nitrogen oxide and its metabolites in the development of embryos

A high content (about a millimole) of compounds, nitrogen oxide (NO) donors, is found in the amniotic fluid of chicken embryos and bovine placenta. Their high content is found also in the blood of newborn calves and chicks before hatching. The possible role of NO and its metabolites in embryogenesis is discussed.     

菌株518鉴定及其次生代谢产物的生防特性与分离

经形态学与分子生物学鉴定,菌株518为淡紫拟青霉。对其进行液体发酵处理,发酵产物对番茄灰霉病有很好的防治效果,同时起到一定的促生长作用。菌体固体发酵后,从中分离得到4种化合物。初步鉴定分别为麦角甾醇、D-甘露糖醇、麦角甾-7,22（E）-二烯-3β,5α,6β-三醇（又称酵母甾醇）、白僵菌素。     

L酪氨酸印迹聚合物的本体聚合法制备及性能

运用本体聚合法制备L-酪氨酸分子印迹聚合物,并考察了聚合物的性能.在单因素试验考察功能单体的种类及用量、交联剂的种类及用量、溶剂种类和反应温度对制备分子印迹聚合物影响的基础上,进一步以3水平4因素的正交试验优化反应条件.利用傅立叶红外光谱分析聚合物的结构,通过荧光分光光度法分析聚合物对L-酪氨酸的选择性吸附、萃取效率和...     

植物内生菌及其代谢产物在生物农药创制中的应用

基于植物内生菌在生物农药创制中的重要性和实践意义,综述植物内生菌的多样性及其在植物不同部位中的分布,不同内生真菌、细菌和放线菌及其代谢物在抑菌杀虫中的生物活性.并就植物内生菌在生物农药创制中的应用展望,提出今后研究的重点和方向.     

硫丹及其主要代谢产物对紫色土中酶活性的影响

采用室内避光培养,研究了硫丹及其主要代谢产物(硫丹硫酸盐和硫丹二醇)在紫色土中的质量浓度变化及其对土壤酶活性的影响。结果表明,α-、β-硫丹在紫色土中的消解过程符合一级反应动力学方程,半衰期分别为32-99d和69-116 d。代谢产物硫丹硫酸盐浓度在前20 d增加较快,30 d后基本趋于稳定;硫丹二醇浓度先增加后减小,15 d时达到最大。5 mg/kg的硫丹处理5 d时对脲酶和硝酸还原酶活性起激活作用,随着培养时间的增加,硫丹处理对脲酶活性从无显著影响逐渐转向抑制,第60天时抑制作用达到最大;高浓度处理(100 mg/kg)强烈抑制脲酶活性,最大降幅达到94.5%。硫丹处理(除5 mg/kg外)对硝酸还原酶活性起抑制作用,浓度越大,抑制作用越强,最大降幅达到89.9%。5 mg/kg的处理抑制多酚氧化酶活性,10-20 mg/kg的处理30 d后由激活逐渐转向抑制;100 mg/kg的处理起激活作用,第15天时酶活性达到最大,随后持续下降,第60天时恢复到对照水平。偏相关分析表明,脲酶、硝酸还原酶活性与硫丹硫酸盐浓度呈显著负相关,硫丹硫酸盐抑制这两种酶的活性;多酚氧化酶活性与α-、β-硫丹、硫丹硫酸盐和硫丹二醇浓度的偏相关性不显著。     

呋虫胺及其代谢物在甘蓝上残留检测及膳食风险评估

为研究呋虫胺在甘蓝上的消解动态规律及评价呋虫胺在甘蓝上长期膳食摄入风险,分别于2015、2016年在湖北、安徽和河北进行规范残留试验,建立高效液相色谱-质谱法(HPLC-MS)检测呋虫胺及其代谢物在甘蓝中残留的分析方法,并评估呋虫胺在甘蓝上的长期慢性膳食暴露风险.样品经乙腈-乙酸溶液超声提取,盐析离心,上层清液经QuEChERS法净化后,用HPLC-MS检测.结果 表明:呋虫胺及其代谢物1-甲基-3-(四氢-3-呋喃甲基)脲(UF)和1-甲基-3-[(3-四氢呋喃)甲基]二氢胍盐(DN)在甘蓝中平均回收率为56％～97％,相对标准偏差(RSD)为3％～16％,呋虫胺在甘蓝上最低检测浓度为0.05 mg·kg-1.呋虫胺在甘蓝中降解半衰期为1.8～4.4 d.膳食摄入风险评估结果显示,我国各类人群的呋虫胺国家估计每日摄入量(NEDI)为0.706～1.604 μg·kg-1,风险商值(RQ)为0.008～0.321,表明呋虫胺在甘蓝上的长期膳食摄入风险较低.     

肌原纤维蛋白凝胶研究进展

肌原纤维蛋白质是肌肉中一类重要的结构蛋白质群,它对于肉食制品的品质和特性具有非常重要的影响.综述了肌原纤维蛋白质的性质、成胶机制,影响其成胶的重要因素及其胶凝性在肉制品加工中的应用,为其以后在肉制品加工中更为广泛的应用提供了理论指导作用.     

Chlorpromazine: direct measurement of differential behavioral effect

A retarded child with a high stereotyped rocking rate was conditioned to pull a ball on a reinforcement schedule in which the fixed ratio aof rewarded to nonrewarded responses was 100. Results show no rocking movements during ball-pulling; but when ball-pulling was on extinction, rocking returned to its original rate. Chlorpromazine blocked rocking movements during extinction, but had no effect on ball-pulling. Delivery of one free reinforcer was sufficient to reinstate ball-pulling after extinction, but the stimulus properties of the free reinforcer were not affected by the drug.