Norepinephrine uptake into cerebral cortical synaptosomes after one fight or electroconvulsive shock

Membrane affinity for the neurotransmitter norepinephrine is rapidly but reversibly decreased in nerve terminals of the cerebral cortex by intense nervous stimulation. This should adaptively facilitate alerting during acute emergency and stress. The Michaelis constant (K(m)) for the high-affinity active uptake of norepinephrine into crude synaptosome-rich homogenates of the cerebral cortices of mice was increased 68 percent after 15 minutes of intense fighting and 110 percent 5 minutes after a single electroconvulsive shock. These changes were no longer evident 18 to 20 hours later.     

ACETOPHENAZINE AND FIGHTING BEHAVIOR IN MICE

Assuming fear to be a variable of importance in the inhibition of aggressive behavior, we used acetophenazine to try to facilitate fighting in mature male C57BL mice. Drugged pairs did not differ significantly from controls in fighting latency; however, the time lapse from the first fight to submission and the actual fighting time to submission were significantly longer for drugged pairs. An attempt is made to relate what is known of the action of the drug with research on the neural correlates of aggressive behavior.     

水浮莲(Pistia stratiotes L．)对NH_4~+-N和NO_3~--N吸收动力学研究

水体中的营养元素过多（特别是氮、磷）所导致的富营养化现象已是全球性的环境问题。近来利用大型维管束植物对富营养化水体的修复已备受关注。然而,水体中氮的去除受到包括氮的离子形态及其在水体中浓度等各种因素的影响。研究通过Michaelis—Menten动力学方程来研究植物根系表面氮的浓度与植物吸收氮的相互关系。该方程包括2个参数：吸收最大速率（Vmox）和米氏常数（Km）,其分别表示植物吸收不同氮形态的最大速率和对不同氮形态亲和力的高低。利用加权回归分析结果表明,生长在不同浓度营养液水浮莲（Pistia stratiotes L．）吸收速率拟和Michaelis—Menten方程。水浮莲对NH4^＋LN的Km很高。表明其对NH4^＋-LN亲和力高;在NO3^--N单一氮源提供下,水浮莲对NO3^--N的吸收动力学与NH4^＋-N相似。然而,在营养液中同时存在NH4^＋-N和N03^--N时,NO3^--N吸收的最大速率明显降低,但对其Km的影响不大,这种抑制作用看来属于非竞争性的。在NH4^＋-LNN和NO3^--N的同时存在下,由于植物吸收NO3^--N能力的降低可能导致植物对氮的利用率下降。     

不同条件下小麦根系吸收菲的动力学参数变化

为揭示植物根系吸收多环芳烃(PAHs)的生物化学机制,建立疏水性有机污染物的植物根系吸收数学模型,并为科学预测农作物的污染风险提供依据,采用水培方法研究了不同温度、pH、培养时间以及地上部分去除与否条件下小麦根系吸收菲的动力学参数的变化规律。结果表明,在15~30℃范围内,小麦根系菲吸收的Km(米氏常数)、Vmax(最大吸收速率)随着温度的升高而增大,Km、Vmax与温度的关系满足指数函数关系;当温度达到35℃时,Km和Vmax的值均出现了下降;在pH为3.00~8.00时,小麦根系对菲的亲和力随着pH的升高而降低,pH为5.50时Vmax达到最大值;幼苗期小麦根系对菲的亲和力随着苗龄的增加而增大,Vmax随着苗龄的增加而减小;活体根和离体根的菲吸收动力学差异不明显。研究显示,温度、pH、苗龄均能显著影响小麦根系菲吸收的动力学参数。     

不同品种花生耐盐性及Na~+吸收动力学特性

为了探究不同品种花生(花育20、花育25和花育36)幼苗的Na~+吸收动力学特性与耐盐性的关系,采用水培试验,研究了不同盐胁迫浓度下,不同花生品种幼苗的干物质积累变化、Na~+吸收动力学特性、Na~+吸收速率、Na~+排斥率与其耐盐性的关系。结果表明:花生对Na~+的吸收可分为高亲和、低亲和2个吸收阶段。低盐胁迫下,花生的Na~+亲和力常数(K_m)小,选择性强,Na~+排斥率平均值在85%左右;在高盐胁迫环境下为低亲和系统,K_m值大,Na~+最大吸收速率(V_(max))大,同时其排斥率较低。低盐胁迫下,花育20、花育25和花育36对Na~+的吸收速率较小,排斥率较高,Na~+积累慢,盐害轻;高盐胁迫下,花育20的Na~+吸收速率高于花育25和花育36,而Na~+排斥率低于花育25和花育36。因此高盐胁迫下,较高的Na~+吸收速率和较低的Na~+排斥率可能是花育20耐盐性弱于花育25和花育36的主要原因。     

Rat fighting behavior: serum dopamine- -hydroxylase and hypothalamic tyrosine hydroxylase

Male Sprague-Dawley rats were subjected to 4 weeks of daily periods of immobilization stress. One of two experimental groups was allowed 1 month of recovery. After 4 weeks of stress, there was a significant increase in shockinduced fighting, in the activity of serum dopamine-beta-hydroxylase, and in the activity of hypothalamic tyrosine hydroxylase. The concentration of hypothalamic norepinephrine was not decreased. After 4 weeks of recovery, only serum dopamine-betahydroxylase activity returned to normal; it therefore appears that longterm stress may increase central catecholamine synthesis. possibly resulting in a persistent increase in aggressive behavior.     

Narcotic drugs: effects on the serotonin biosynthetic systems of the brain

The effects of short- and long-term administration of morphine on the activity of two measurable forms of rat brain tryptophan hydroxylase were studied. Morphine administration produced an immediate decrease and a longterm increase in the nerve ending (particulate) enzyme activity but did not change the cell body (soluble) enzyme activity. Cocaine administration demnonstrated a short-term decrcease in measurable nerve eniding enzyme activity that was due to the inhibition of the high affinity uptake (the Michaelis constant, K(m) is 10-(5) molar) of trytophan, the serotonin precursor. Cocaine did not aflect the low affinity uptake K(m) = 10-(5) molar) of tryptophan. Both the uptake of the precursor and the enizymiie activity appeared to be drug-sensitive regullatory processes in the biosynthlesis of serotonin.     

Evidence from cassette mutagenesis for a structure-function motif in a protein of unknown structure

The three-dimensional structure of most enzymes is unknown; however, many enzymes may have structural motifs similar to those in the known structures of functionally related enzymes. Evidence is presented that an enzyme of unknown structure [Ile-transfer RNA (tRNA) synthetase] may share a functionally important structural motif with an enzyme of related function (Tyr-tRNA synthetase). This approach involves (i) identifying segments of Ile-tRNA synthetase that have been unusually conserved during evolution, (ii) predicting the function of one such segment by assuming a structural relation between Ile-tRNA synthetase and Tyr-tRNA synthetase, and (iii) testing the predicted function by mutagenesis and subsequent biochemical analysis. Random mutations were introduced by cassette mutagenesis into a ten-amino-acid segment of Ile-tRNA synthetase that was predicted to be involved in the formation of the binding site for isoleucine. Few amino acid substitutions appear to be tolerated in this region. However, one substitution (independently isolated twice) increased the Michaelis constant Km for isoleucine in the adenylate synthesis reaction by greater than 6000-fold, but had little effect on the Km for adenosine triphosphate, the apparent Km for tRNA, or the rate constant kcat.     

Pharmacologic effects in man of a specific serotonin-reuptake inhibitor

Fluoxetine (Li-ly 110140) caused a 63 percent inhibition of [3H]serotonin uptake into platelets obtained from normal volunteers to whom the drug was administered daily for 7 days. This dose had no effect on the usual pressor response produced by injections of norepinephrine or tyramine.     

Catecholamine uptake in cerebral cortex: adaptive change induced by fighting

The name of the senior author of "Catecholamine uptake in cerebral cortex: an adaptive change induced by fighting" (8 June 1973, page 1050) was misspelled. It should be Edith D. Hendley and not Edith D. Henley.     

有机物料对平邑甜茶根系32P吸收动力学参数的影响

 研究了3种有机物料对平邑甜茶实生苗吸收根、生长根、褐色木质根磷吸收的影响。结果表明，3类根对磷的吸收均符合离子吸收动力学模型。有机物料的加入均不同程度地提高了Imax，而Km有所降低。不同处理间根系磷吸收动学力学参数有差异：在夏季各类根的Imax表现为鸡粪处理>羊粪处理>花生秧处理，秋季为羊粪处理>鸡粪处理>花生秧处理（Km值的大小顺序与之相反）。3类根的磷吸收动力学参数差异较大，吸收根其Imax是褐色木质根的7.4～8.7倍，生长根是褐色木质根的4.7～5.8倍。而褐色木质根的Km值是吸收根的1.1～1.5倍，是生长根的1.0～1.2倍。说明吸收根和生长根对磷的吸收潜力、与磷的亲和力均大于褐色木质根。夏季根系对磷的最大吸收速率与植株生物量呈极显著正相关，秋季未达到显著水平（褐色木质根除外）。     

Uptake of tritium-labeled norepinephrine in brain and other tissues of cat in vitro

Slices of cat cerebral cortex, heart, and spleen that have been incubated in media containing approximately 5 to 25 mmicrog of dl-norepinephrine-7H(8) per milliliter contain levels of isotopic amine greater than those in the medium. The effects of norepinephrine concentration, reserpine, and ouabain on the uptake suggest that the amine enters cells both by diffusion and by a concentrating miechanism that is saturated at low levels of norepinephrine. The drugs inhibit the latter.     

玉米幼苗根系吸收硫酸盐(Na_2~(35)SO_4)效率与产量杂种优势的关系

本文以来源不同的９个自交系及其按双列杂交组成的３６个正交Ｆ１组合为材料， 研究了玉米幼苗根系吸收硫酸盐（Ｎａ３５２ＳＯ４）的动力学参数（Ｋｍ和Ｖｍａｘ）与产量杂 种优势（Ｈ）的关系·结果表明，Ｖｍａｘ与Ｈ无明显的数量关系，Ｋｍ与Ｈ间呈显著的 直线相关（ｒ＝－０．３３３１，Ｐ＜０．０５）．Ｋｍ可作为早期预测产量杂种优势的一个生理 参考指标。     

Ammonium Effects on Nitrate Uptake by Roots of Upland and Paddy Rice Seedlings Related to Membrane Potential Differences

Nitrate uptake characteristics and ammonium effects on nitrate uptake were compared between upland rice （Brazilian upland rice） and paddy rice （Wuyujing 3 and Yangdao 6） through the glass microelectrode technique and the concentration gradient method of uptake kinetics.Results indicated that nitrate uptake by rice seedlings and ammonium effects were depending on membrane potential of root cells.And upland rice and paddy rice presented obviously different responses.For all cultivars,the nitrate treatments induced rapid depolarization and then slow repolarization of membrane potential in root epidermal cells,and even hyperpolarization was observed when nitrate concentration was low.The membrane potential of epidermal cells in Brazilian upland rice roots was larger and its response to NO3- was bigger than those of two paddy rice cultivars.Depolarization of membrane potential was amplified when ammonium was simultaneously added with nitrate into the measure medium,but repolarization was reduced,even disappeared.Brazilian upland rice seedlings had high Vmax of nitrate uptake and low Km,furthermore,Vmax and Km were little affected by ammonium,but Vmax of Wuyujing 3 was reduced significantly.Therefore,inhibition of NH4＋ differed obviously between upland rice and paddy rice.     

赤拟谷盗乙酰胆碱酯酶生化及毒理学特性研究

为了阐明赤拟谷盗[Triboliumcastaneum(Herbst)]体内乙酰胆碱酯酶(AChE)在其各虫态间的变化关系,以期为该虫的综合治理提供一定的理论依据,本试验采用微量滴度酶标板法,分别对其10d龄和20d龄幼虫、蛹及成虫体内AChE的生化及毒理学特性进行了较为系统的研究。结果表明,赤拟谷盗各虫态AChE酶源蛋白含量、酶活力和比活力差异显著,酶源蛋白含量从低到高依次为:10d龄幼虫<20d龄幼虫<成虫<蛹;AChE活力和比活力依次为:成虫<蛹<10d龄幼虫<20d龄幼虫。酶动力学分析发现,AChE米氏常数Km值大小依次为:蛹<成虫<10d龄幼虫<20d龄幼虫,但成虫和蛹之间的差异不显著。此外,幼虫AChE的最大反应速度Vmax亦显著高于成虫和蛹。通过对幼虫AChE离体抑制作用测定表明,毒扁豆碱、马拉氧磷和西维因对20d龄幼虫的抑制中浓度I50均高于10d龄幼虫,说明20d龄幼虫体内的AChE对3种抑制剂的抑制作用更不敏感。     

不同烤烟基因型钾吸收特性及其根皮层细胞内向钾电流差异研究

对4个烤烟基因型进行了根系钾吸收动力学特性研究,并对其根皮层细胞质膜内向跨膜钾电流进行了全细胞记录.结果表明,农大202与NC 89的Vmax明显高于净叶黄及NC 2326,而它们的Km值则低于净叶黄及NC2326.全细胞内向跨膜钾电流的记录表明,NC 89的电流密度(pA/pF)最高,其次为农大202及净叶黄,而以NC2326的电流密度最小.结果还表明,基因型对K 亲和力及吸收能力是影响烤烟钾营养效率高低的重要因素.     

牦牛乳酸脱氢酶A的分离纯化、酶学性质及其基因的克隆

 【目的】分离纯化牦牛骨骼肌中的乳酸脱氢酶-A（LDH-A）,并克隆其cDNA。通过比较牦牛与普通牛的LDH-A的酶学性质和cDNA序列,为研究牦牛适应高海拔、低氧环境,在分子水平上找到一些线索。【方法】采用染料亲和层析和DEAE-Sephadex离子交换层析等方法,分别从牦牛和普通牛骨骼肌中纯化LDH-A,并对其酶学性质进行比较;通过RT-PCR方法克隆牦牛LDH-A的cDNA序列,并与GenBank登录的普通牛LDH-A的cDNA序列进行比对。【结果】纯化的牦牛LDH-A比活力为103.9 U•mg-1蛋白,纯化倍数为18.2。SDS-PAGE和PAGE分析均显示一条带。酶动力学参数测定显示,牦牛LDH-A的Km NADH为0.097,Km 丙酮酸钠为1.897,均不同程度高于普通牛,其中对丙酮酸钠的Km大约是普通牛的2倍。根据牦牛LDH-A的cDNA序列预测的氨基酸序列与普通牛LDH-A的氨基酸序列比较,只有2个氨基酸残基的改变（257Val-Ala和315Tyr-Cys）。【结论】牦牛LDH-A对丙酮酸的高Km可避免骨骼肌中产生过多的乳酸,是适应进化的结果;这种升高可能与其氨基酸序列变化导致的空间结构微小改变有关。     

Physiological variation in alpha-adrenoceptor-mediated arterial sensitivity: relation to agonist affinity

Vascular smooth muscle from different arteries of the rabbit varies in sensitivity to norepinephrine, even when factors known to contribute to this variation are excluded. Sensitivity to norepinephrine mediated through the alpha-adrenoceptor is linearly related to the agonist dissociation constant, but is not significantly related to receptor reserve. These results suggest that agonist affinity is the primary determinant of sensitivity to norepinephrine, at least in these arteries, and that this is a locally regulated characteristic which may account for regional sensitivity changes.     

Selective chemical catalysis by an antibody

The immunoglobulin MOPC167, which binds the transition state analog p-nitrophenylphosphorylcholine with high affinity, catalyzed the hydrolysis of the corresponding carbonate 1. MOPC167 catalysis displayed saturation kinetics with catalytic constant (kcat) = 0.4 min-1 and Michaelis constant (Km) = 208 microM, showed substrate specificity, and was inhibited by p-nitrophenylphosphorylcholine. The rate of the reaction was first order in hydroxide ion concentration between pH 6.0 and 8.0. The lower limit for the rate of acceleration of hydrolysis by the antibody above the uncatalyzed reaction was 770. This study begins to define the rules for the generation of catalytic antibodies.     

Purification and reconstitution of chloride channels from kidney and trachea

Chloride channels mediate absorption and secretion of fluid in epithelia, and the regulation of these channels is now known to be defective in cystic fibrosis. Indanyl-oxyacetic acid 94 (IAA-94) is a high-affinity ligand for the chloride channel, and an affinity resin based on that structure was developed. Solubilized proteins from kidney and trachea membranes were applied to the affinity matrix, and four proteins with apparent molecular masses of 97, 64, 40, and 27 kilodaltons were eluted from the column by excess IAA-94. A potential-dependent 36Cl- uptake was observed after reconstituting these proteins into liposomes. Three types of chloride channels with single-channel conductances of 26, 100, and 400 picosiemens were observed after fusion of these liposomes with planar lipid bilayers. Similar types of chloride channels have been observed in epithelia.