Role of electrostatics in the binding of charged metallophthalocyanines to neutral and charged phospholipid membranes

Binding of the cationic tetra(tributylammoniomethyl)-substituted hydroxoaluminum phthalocyanine (AlPcN₄) to bilayer lipid membranes was studied by fluorescence correlation spectroscopy (FCS) and intramembrane field compensation (IFC) methods. With neutral phosphatidylcholine membranes, AlPcN₄ appeared to bind more effectively than the negatively charged tetrasulfonated aluminum phthalocyanine (AlPcS₄), which was attributed to the enhancement of the coordination interaction of aluminum with the phosphate moiety of phosphatidylcholine by the electric field created by positively charged groups of AlPcN₄. The inhibitory effect of fluoride ions on the membrane binding of both AlPcN₄ and AlPcS₄ supported the essential role of aluminum-phosphate coordination in the interaction of these phthalocyanines with phospholipids. The presence of negative or positive charges on the surface of lipid membranes modulated the binding of AlPcN₄ and AlPcS₄ in accord with the character (attraction or repulsion) of the electrostatic interaction, thus showing the significant contribution of the latter to the phthalocyanine adsorption on lipid bilayers. The data on the photodynamic activity of AlPcN₄ and AlPcS₄ as measured by sensitized photoinactivation of gramicidin channels in bilayer lipid membranes correlated well with the binding data obtained by FCS and IFC techniques. The reduced photodynamic activity of AlPcN₄ with neutral membranes violating this correlation was attributed to the concentration quenching of singlet excited states as proved by the data on the AlPcN₄ fluorescence quenching.     

Properties of aminoglycoside-3'-phosphotransferases determined by kanamycin transposones Tn 601 and Tn 5

Aminoglycoside-3'-phosphotransferase I and II (APT-3'-I and APT-3'-II) has been purified to homogenity from the cells of E. coli containing the plasmids R6 and JR67, respectively. The purification procedure involved competitive affinity chromatography on neomycin-sepharose and gel-filtration on Sephadex G-100. The specific activity of APT-3'-I with the substrates--lividomycin A, neomycin B, paromycin, ribostamycin, kanamycins A and B--are 4.3, 2.8, 2.1, 1.6, 0.9 and 0.8 mol/min. mg protein, respectively. The specific activity of APT-3'-II with the substrates--ribostamycin, paromycin, kanamycins A and B, neomycin B--are 8.0, 7.2, 4.0, 4.5 and 3.6, respectively. Mg2+ is required for the activity of both enzymes. Co2+, Zn2+ and Mn2+ are active in case of APT-3'-I; however, these cations are less active than Mg2+. The pH-optimum of APT-3'-I and APT-3'-II is 7.0--7.5. High ionic strength is required for the activity of both enzymes. The molecular weights of APT-3'-I and APT-3'-II are about 36 000 and 26 000, respectively. The amino acid composition of APT-3'-I and APT-3'-II was determined. Both enzymes contain tryptophane residues whose fluorescence intensity decreased when ATP, but not amino-glycoside antibiotics, is added. The interrelationship between the molecular weights of these enzymes and the sizes of the loops of transposones Tn 601 and Tn 5, encoding APT-3'-I and APT-3'-II, is discussed.     

正常小鼠高频心电图时域值和功率谱的研究

本文用南京新博公司生产的ＮＨＥ－１０００型心电高频信息检测分析仪研究了正常小鼠（昆明种）高频心电图（ＨＦ－ＥＣＧ）的时域值和ＱＲＳ波群的功率谱。主要结果如下（以正导为例,－Ｘ±ＳＤ）：心率６０３±８８次／ｍｉｎ（ｎ＝７４）;Ｐ－Ｒ间期相对较长。为３４．９±４．７ｍｓ（ｎ＝５８）,占心动周期的３４．９±４．９％,这与人类有很大的不同;ＱＲＳ波宽９．２±１．２ｍｓ,占心动周期的９．２±１．４％（ｎ＝７４）,这一结果与以前的文献报道相差较大。Ｔ波宽１０．３±３．２ｍｓ,占心动周期的１０．３±３．２％;Ｑ－Ｔ间期１９．４±３．２ｍｓ,占心动周期的１９．５±３．６％;ＱＲＳ波群峰－峰值（Ｖｐ－ｐ）为１．４５６±０．４８０ｍＶ;Ｔ波高０．３３６±０．１１５ｍＶ;７３只动物Ⅱ导联高频切迹总数只有３个,扭挫２６个。Ⅱ导联ＱＲＳ波群的功率谱特点：０—８０Ｈｚ的相对能量为４５．４８±１５．３２％;８０—２００Ｈｚ为４３．９７±９．９５％;２００—３００Ｈｚ为８．８９±７．３８％;３００—１０００Ｈｚ为１．６６±２．７４％。     

The effect of concentration of organic substances on the dynamics of accumulation and decomposition of individual amino acids during methane generation of organonitrogen substrates

The content of 17 individual amino acids contained in nitrogen-organic matter of poultry dung was being studied in the course of the dung conversion into biogas. The concentration of organic matter and ammonium ions had no effect on the rate of the amino acid conversion, but influenced the decomposition and accumulation of individual amino acids. The intensive de novo synthesis of some amino acids was observed during methane generation of poultry dung.     

Activity in the myelin fibers of the cat cutaneous nerve in response to heating]

The collision method combined with some techniques improving the signal-to-noise ratio showed that the activation in the nerve fiber group A gamma 1, A delta, A delta 2 and in "mixed" fibers group was changed by hairy skin heating. A relatively great number of nerve fibers of these groups were activated and only an insignificant part of them inhibited their activity in response to the cutaneous receptor heating. A spontaneous activity increase and skin relaxation under heating. were shown.     

17个建兰品种光合特性分析

以17个建兰(Cymbidium ensifolium)品种为材料,采用改良的丙酮法提取叶绿素,再通过Arnon丙酮法公式计算光合色素含量,利用捷克FluorCam开放式叶绿素荧光仪测定不同品种的叶绿素荧光参数。结果表明,17个建兰品种的光合色素和叶绿素荧光参数具有不同程度的差异,其中‘铁骨素’(C. ensifolium ‘Tiegusu’)、‘逸红双娇’(C. ensifolium ‘Yihongshuangjiao’)和‘闽南黄蝶’(C. ensifolium ‘Minnanhuangdie’)的光合色素含量高于其他品种,表明这3个品种具有良好的光合效率,吸收光能的能力较强;‘铁骨素’最大荧光产量(Fm)、Kautsky诱导效应最大荧光(Fp)、PS Ⅱ原初光能转化效率(Fv/Fm)和非光化荧光淬灭系数(NPQ)均为最高。综上可知,‘铁骨素’的光合生理特性优于其他品种,可作为优良建兰品种进行种植推广。     

小叶锦鸡儿天然居群叶形态性状变异研究

为揭示小叶锦鸡儿(Caragana microphylla)天然居群叶形态性状的变异规律及其生态适应性特征,该研究以10个小叶锦鸡儿天然居群为对象,通过多重比较、巢式方差分析、相关性分析、聚类分析和主成分分析等方法,对7个叶形态性状进行分析。结果表明：(1)小叶锦鸡儿叶形态性状在居群内和居群间均存在极显著差异(P < 0.01),平均变异系数为10.13%,不同性状的变异幅度为6.23%~12.78%;平均叶形态性状的表型分化系数为43.62%,居群内变异(30.09%)大于居群间变异(24.91%),说明居群内是其叶形态性状变异的主要来源。(2)相关性分析表明,环境因子对小叶锦鸡儿的叶形态性状变异有很大的影响,在地理空间上主要呈现出沿海拔梯度的变异模式;主成分分析的结果显示,小叶宽、叶柄宽和叶柄长对小叶锦鸡儿叶形态变异起主导作用;利用欧式距离对小叶锦鸡儿居群进行UPGMA聚类分析结果显示,基于叶形态性状和环境因子可分别将小叶锦鸡儿10个居群分为3类和2类,Mantel检验结果表明,小叶锦鸡儿的叶形态性状变异不存在地理连续性。研究结果为小叶锦鸡儿的适应性进化和开发利用提供了理论依据。     

H2S作为下游信号参与SA对低温弱光下黄瓜幼苗光合作用的调控

水杨酸(SA)和硫化氢(H₂S)在调控非生物胁迫下植物生长发育和生理代谢中均起着非常重要的作用,但二者作为信号分子在调控低温弱光下黄瓜光合作用中的互作关系还不清楚。本试验以黄瓜幼苗为试材,分别用SA和硫氢化钠(NaHS,H₂S供体)及其清除剂或抑制剂喷撒叶面,以适宜温光下去离子水处理为对照(CK),研究低温(8 ℃/5 ℃,昼/夜)弱光(100 μmol·m^-2·s^-1)下SA和H₂S对黄瓜幼苗光合作用的调控及互作关系。结果表明: SA可明显增强L-/D-半胱氨酸脱巯基酶(LCD、DCD)活性及其mRNA表达,促进内源H₂S产生;NaHS对苯丙氨酸解氨酶和异分支酸合成酶活性、mRNA表达量及内源SA含量影响不大。SA和NaHS可使低温弱光下黄瓜幼苗的光合速率、气孔导度和蒸腾速率明显提高,胞间CO₂浓度显著降低;同时增强核酮糖-1,5-二磷酸羧化酶、Rubisco活化酶、景天庚酮糖-1,7-二磷酸酯酶和果糖-1,6-二磷酸醛缩酶活性及其mRNA表达,促进光合碳同化;提高光下PSⅡ实际光化学效率和暗下PSⅡ最大光化学效率,从而减轻低温弱光胁迫对黄瓜幼苗的光合机构的损伤和生长量的影响。H₂S清除剂次牛磺酸(HT)可使SA对低温弱光下黄瓜幼苗的光合作用和生长促进效应明显减弱,而SA抑制剂多效唑和氨基茚磷酸对H₂S诱导的黄瓜幼苗光合机构对低温弱光的耐受性无显著影响,说明H₂S作为SA的下游信号,参与调控低温弱光下黄瓜幼苗的光合作用。