GABAA-receptor function in hippocampal cells is maintained by phosphorylation factors

Gamma aminobutyric acid (GABA) mediates fast synaptic inhibition in the central nervous system by activating the chloride-permeable GABAA channel. The GABAA conductance progressively diminishes with time when the intracellular contents of hippocampal neurons are perfused with a minimal intracellular medium. This "run down" of the GABA-activated conductance can be prevented by the inclusion of magnesium adenosine triphosphate and calcium buffer in the intracellular medium. The amount of chloride conductance that can be activated by GABA is determined by competition between a calcium-dependent process that reduces the conductance and a phosphorylation process that maintains the conductance.     

Nitric oxide reduction coupled with carbon monoxide oxidation in the presence of soluble metal catalysts

Solutions of RhCl(3).xH(2)O in ethanol and Ru(NO)(2)[P(C(6)H(5))(3)](2) in benzene catalyze the reduction of nitric oxide to nitrous oxide concomitant with the oxidation of carbon monoxide to carbon dioxide at ambient temperature and atmospheric pressure. The reaction, which is followed by gas chromatography and by the decrease in pressure of the system, proceeds to 47 percent conversion of the reactants after 63 hours.     

Redox signaling in chloroplasts: cleavage of disulfides by an iron-sulfur cluster

Light generates reducing equivalents in chloroplasts that are used not only for carbon reduction, but also for the regulation of the activity of chloroplast enzymes by reduction of regulatory disulfides via the ferredoxin:thioredoxin reductase (FTR) system. FTR, the key electron/thiol transducer enzyme in this pathway, is unique in that it can reduce disulfides by an iron-sulfur cluster, a property that is explained by the tight contact of its active-site disulfide and the iron-sulfur center. The thin, flat FTR molecule makes the two-electron reduction possible by forming on one side a mixed disulfide with thioredoxin and by providing on the opposite side access to ferredoxin for delivering electrons.     

Sclerotinia sclerotiorum virulence is affected by mycelial age via reduction in oxalate biosynthesis

Sclerotinia sclerotiorum is one of the most devastating necrotrophic phytopathogens. Virulence of the hyphae of this fungus at different ages varies significantly. Molecular mechanisms underlying this functional distinction are largely unknown. In this study, we confirmed the effect of mycelial culture time/age on virulence in two host plants and elucidated its molecular and morphological basis. The virulence of the S. sclerotiorum mycelia in plants dramatically decreases along with the increase of the mycelial age. Three-day-old mycelia lost the virulence in plants. Comparative proteomics analyses revealed that metabolism pathways were comprehensively reprogrammed to suppress the oxalic acid(OA) accumulation in old mycelia. The oxaloacetate acetylhydrolase(OAH), which catalyzes OA biosynthesis, was identified in the S. sclerotiorum genome. Both gene expression and protein accumulation of OAH in old mycelia were strongly repressed. Moreover, in planta OA accumulation was strikingly reduced in old mycelia-inoculated plants compared with young vegetative mycelia-inoculated plants. Furthermore, supply with 10 mmol L~(–1) OA enabled the old mycelia infect the host plants, demonstrating that loss of virulence of old mycelia is mainly caused by being unable to accumulate OA. Additionally, aerial mycelia started to develop from 0.5-day-old vegetative mycelia and dominated over 1-day-old mycelia grown on potato dextrose agar plates. They were much smaller in hypha diameter and grew significantly slower than young vegetative mycelia when subcultured, which did not maintain to progenies. Collectively, our results reveal that S. sclerotiorum aerial hyphae-dominant old mycelia fail to accumulate OA and thereby lose the virulence in host plants.     

毛细管电泳联用电化学发光法测定食品中泰乐菌素的研究

基于泰乐菌素能增强联吡啶钌[Ru(bpy]32+]电化学发光信号的现象,结合毛细管电泳分离技术,建立了动物组织和蜂蜜中泰乐菌素测定的新方法.分别对检测和分离条件进行了优化,在优化的试验条件下,泰乐菌素在浓度为0.05～10.00 μg/mL范围内具有良好的线性关系,检测限为0.02 μg/mL,用于实际样品中泰乐菌素的测定,回收率为80.0%～95.0%.     

The Fos protein complex is associated with DNA in isolated nuclei and binds to DNA cellulose

The properties of the viral and cellular fos proteins (Fos) were investigated as a first step toward understanding the function of the fos gene. Treatment of nuclei with salt and nonionic detergents solubilized a complex that contained Fos together with several other cellular proteins. The majority of the Fos protein complex was released from isolated nuclei incubated in the presence of deoxyribonuclease I or micrococcal nuclease but not with ribonuclease A, suggesting that Fos is associated with chromatin. This hypothesis is supported by the finding that Fos protein from native or denatured nuclear extracts exhibited DNA-binding activity in vitro. These results suggest that Fos is involved in the regulation of gene expression.     

微波辅助提取-高效液相色谱-电感耦合等离子体质谱法测定水产品中甲基汞和乙基汞

建立了水产品中甲基汞和乙基汞的微波辅助提取-高效液相色谱-电感耦合等离子体质谱（HPLC-ICP -MS）测定方法。为保证样品中汞的各形态能完全提取并准确分析,通过条件优化,使用5 mol/L盐酸溶液微波辅助提取样品中的甲基汞和乙基汞,流动相为0.01 mol/L乙酸氨、0.12%(V/V) L-半胱氨酸、8% (V/V) 甲醇-水溶液。提取液在液相色谱中分离后,进入电感耦合等离子体质谱检测,5 min内完成甲基汞和乙基汞的定量分析。在优化的检测条件下,甲基汞和乙基汞检出限分别可达到0.024、0.042 μg/L吗,在0.05~20 μg/L范围内均具有良好的线性关系,相关系数均为0.9999,平均加标回收率为84.0%~94.5%。两种汞形态的批内和批间相对标准偏差分别在2.1%~4.1%和2.6%~4.3%的范围内。该方法具有简单、快速、灵敏度高和定性准确等优点,满足汞形态定量分析的要求。     

Benzodiazepines: anxiety-reducing activity by reduction of serotonin turnover in the brain

The anxiety-reducing effects of minor tranquilizers in the rat conflict test were mimicked by serotonin antagonists and by p-chlorophenylalanine, an inhibitor of serotonin synthesis; the depressant effects of the minor tranquilizers were mimicked by norepinephrine antagonists. Intraventricular injections of serotonin led to a suppression of behavior, and also antagonized the anxiety-reducing action of benzodiazeprines. Intraventricular injections of norepinephrine led to a release of punished behavior from suppression, and also antagonized the depressant action of benzodiazepines. The anxiety-reducing activity, and the decrease in serotonin turnover induced by benzodiazepines, were maintained over repeated doses, whereas depressant activity, and the decrease induced in norepinephrine turnover, both rapidly underwent tolerance. Tranquilizers may exert their anxiety-reducing effects by a reduction of serotonin activity in a behaviorally suppressive punishment system, and they may exert their depressant effects by a reduction of norepinephrine activity in a behaviorally facilitatory reward system.     

液相-电喷雾质谱法测定饲料中脱氧雪腐镰刀菌烯醇的残留量

建立了液相-电喷雾串联质谱法检测饲料中的脱氧血腐镰刀菌烯醇(DON)。样品用磷酸盐缓冲液(pH 7.0)提取,经C18固相萃取净化、5%甲醇再溶解后进行LC-MS/MS分析。质谱采用电喷雾离子源,正离子多重反应监测模式进行定量和定性分析。色谱柱采用Phenomenex Luna 5μC18(2),流动相为甲醇-0.1%甲酸溶液(30:70)。方法的检测限为20μg/kg,定量限为50μg/kg;在50、250、500μg/kg等3个浓度水平,回收率为75.4%~93.2%,相对标准偏差为5.74%～7.62%。     

gamma-Glutamyl transpeptidase in isolated brain endothelial cells: induction by glial cells in vitro

The endothelia of microvessels isolated from mouse brain by mechanical means are rich in gamma-glutamyl transpeptidase; however, the enzyme often disappears when the cells migrate or proliferate from the microvessel isolates. In an endothelial cell line derived from similar isolates and negative for gamma-glutamyl transpeptidase, the enzyme could be induced in the endothelial cells when they were cocultured with glial cells. Thus there may be a requirement for continuous induction of gamma-glutamyl transpeptidase in brain microvessels by adjacent glial cells.     

高效液相色谱原子荧光联用技术测定大米中无机砷

采用高效液相色谱-氢化物发生-原子荧光光谱法建立了大米中无机砷的检测方法,研究了大米研磨粒径、提取剂、提取温度、提取方式对大米中砷提取效率的影响,As(Ⅲ)转化为As(V)的方法,并对流动相进行了对比和优化.结果表明:大米研磨过孔径0.45 mm筛,采用0.02 mol/L的硝酸甲醇水溶液(V∶V=50∶50)作为提取剂,95℃水浴60 min,5 mmol/L丙二酸或15 mmol/L磷酸氢二铵水溶液为流动相,提取效率可达到85％以上,加标回收率为85％～ 110％,相对标准偏差(RSD)小于10％,无机砷的方法检出限(LOD)为8μg/lg.该方法可以应用于大米样品标准物质和市售大米中无机砷的检测.     

腐殖酸键合硅胶固相萃取-气相色谱法快速测定玉米油中拟除虫菊酯类农药残留

为建立适用于玉米油中常见拟除虫菊酯类农药的快速分析方法,以腐殖酸键合硅胶作为固相萃取介质,建立固相萃取富集净化、气相色谱电子捕获检测器检测玉米油中氯氟氰菊酯、氟胺氰菊酯、氟氯氰菊酯、氰戊菊酯、溴氰菊酯、氟氰戊菊酯和氯氰菊酯7种拟除虫菊酯类农药的分析方法.结果表明,在优化好的条件下,上述7种农药在0.01～0.60 mg...     

Rare-Earth manganites: catalysts with low ammonia yield in the reduction of nitrogen oxides

Rare-earth manganites such as La(1-x) Pb(x)MnO(3), with 0.3 x 0.6, and their perovskite-like homologs are active catalysts for the reduction of nitric oxide to molecular nitrogen. At low temperatures, innocuous nitrous oxide rather than anmmonia is the main side product. The activity of single crystalline catalysts and of ceramic catalysts of this type is substantially improved by etching with dilute acids.     

Fast determination of multi-mycotoxins in corn by dispersive solid-phase extraction coupled with ultra-performance liquid chromatography with tandem quadrupole time-of-flight mass spectrometry

A fast analytical method for the simultaneous determination of 9 mycotoxins, including aflatoxins(B_1, B_2, G_1, and G_2), fumonisins(B_1, B_2 and B_3), zearalenone, and deoxynivalenol in corn using dispersive solid-phase extraction method and ultra-performance liquid chromatography coupled to tandem quadrupole time-of-flight mass spectrometry(UPLC-Q-TOFMS) was developed and validated. Samples were extracted with acetonitrile-water(84:16, v:v, containing 1% acetic acid) using ultrasonic extraction. The extracts were purified with a dispersive SPE method using C18 as a cleaning agent. The final clear extracts were dried by nitrogen blowing and subsequently redissolved in methanol-water(5:5, v:v). The samples were then analyzed by UPLC-Q-TOF-MS with 0.1% formic acid in ammonium acetate-methanol as mobile phase. The mean recoveries were ranged from 68.0 to 120.0%, and the relative standard deviation(RSD) ranged from 0.18 to 6.29%. Limits of detections ranged from 0.05 to 50 μg kg~(-1), and limits of quantification ranged from 0.1 to 200 μg kg~(-1), which were below the legal limits set by the European Union for the legislated mycotoxins. The developed method was applied to 130 corn samples. Among the mycotoxins studied, aflatoxins B_1 and fumonisins B_1, B_2 and B_3 were the most predominant mycotoxins, and their concentrations were 0–593.12, 0–2.01×10~4, 0–6.94×10~3 and 0–3.05×10~3 μg kg~(–1), respectively.     

加速溶剂提取-固相萃取净化-双柱双检测器气相色谱法测定大气中多种有机氯农药

选择大流量采样器采集大气样品,采用加速溶剂萃取仪进行样品萃取,弗洛里硅土固相萃取柱进行净化,以双柱双电子捕获检测器-气相色谱法测定环境空气中23种有机氯农药.采用内标法定量,23种有机氯农药和回收率指示物在10～300 μg·L-1的质量浓度范围内呈现良好的线性关系(相关系数均大于0.997),加标回收率在60.1％～...     

基于离子液体的分散液相微萃取-高效液相色谱法测定水中三唑类农药

应用分散液相微萃取(DLLME)技术,建立水体中三唑醇(Triadimenol)、腈菌唑(Myclobutanil)、氟硅唑(Flusilazole)、戊唑醇(Tebuconazole)、己唑醇(Hexaconazole)、烯唑醇(Diniconazole)等6种三唑类农药的高效液相色谱(HPLC)分析方法,观察了萃取剂种类、萃取体积、萃取时间、涡旋速度、盐浓度和溶液pH值对萃取效率的影响,确定了最佳萃取条件:以100μL 1-丁基-3-甲基咪唑六氟磷酸盐(1-butyl-3-methylimidazoliumhexafluorophosphate,[BMIM]PF6)离子液体为萃取剂,在涡旋速度为2 500r/min的条件下,对pH 4、NaCl质量分数为4%的5mL水溶液涡旋萃取3min。检测结果表明:6种三唑类农药在0.03～20.00mg/L质量浓度范围内呈良好的线性关系,线性相关系数为0.999 6～0.999 9;检出限为0.002～0.006mg/L(S/N=3);对自来水、湖水和稻田水的加标回收率为69.7%～101.0%,变异系数为2.7%～8.6%。     

8种木本植物木质部栓塞变化与生理生态指标间关系的研究(II)——与光合生理生态指标的关系

选取西北农林科技大学西林校区校园内自然状况下生长良好的耐旱树种刺槐(Robin iap seudoacacia)、元宝枫(A cer truncatum)、沙棘(H ippophae rhamnoid es)、白榆(U lmus pum ila)、油松(P inus tabu laeform is)、白皮松(P inus bungeana)及中生树种女贞(L igustrum lucidum)、柳树(S a lix m atsud ana K o idz.f.pendu la)为研究对象,测定了它们3个季节内的木质部栓塞日变化规律及其与光照强度、大气温度、气孔导度、蒸腾速率等生理生态指标的关系。结果表明:光照强度、大气湿度和大气温度主要是通过对植物气孔运动、蒸腾作用和体内水分关系的调节对木质部栓塞起作用的;木质部栓塞是植物一天生长过程中不可避免的“平常事件”,与植物的光合速率、蒸腾速率、气孔导度和水分利用效率间存在一定的相关关系;它的发生和恢复可能是某些植物适应水分胁迫的一种机制。     

8种木本植物木质部栓塞变化与生理生态指标间关系的研究(Ⅱ)--与光合生理生态指标的关系

选取西北农林科技大学西林校区校园内自然状况下生长良好的耐旱树种刺槐（Robinia pseudoacacia）、元宝枫（Acer truncatum）、沙棘（Hippophae rhamnoides）、白榆（Ulmus pumila）、油松（Pinus tabulae formis）、白皮松（Pinus bungeana）及中生树种女贞（Ligustrum lucidum）、柳树（Salix matsudana Koidz．f．pendula）为研究对象，测定了它们3个季节内的木质部栓塞日变化规律及其与光照强度、大气温度、气孔导度、蒸腾速率等生理生态指标的关系。结果表明：光照强度、大气湿度和大气温度主要是通过对植物气孔运动、蒸腾作用和体内水分关系的调节对木质部栓塞起作用的；木质部栓塞是植物一天生长过程中不可避免的“平常事件”，与植物的光合速率、蒸腾速率、气孔导度和水分利用效率间存在一定的相关关系；它的发生和恢复可能是某些植物适应水分胁迫的一种机制。