TWO FORMS OF NEURONAL ACTIN

Abstract— —Cultures of neurons essentially free of non-neuronal cells were prepared from chick sympathetic neurons and from sensory neurons that had been enriched on a simple density gradient. The proteins of these cultures were examined by two-dimensional gel electrophoresis and two species found in each type of nerve cell that ran close to, but not precisely with, muscle actin. They comigrated with the β and γ actins previously seen in developing myoblasts (W halen et al. , 1976). Peptide patterns obtained from the two neuronal proteins by limited papain digestion, as well as from three analogous proteins of cultured fibroblasts and purified chicken muscle actin, were extremely similar. The same two species, in similar amounts, were found in soluble and residual fractions of cultured neurons produced by brief detergent treatment; in fractions enriched for neuronal processes or cell soma from cultured sensory ganglia; and in purified actin recovered from material released upon gentle homogenisation of embryonic chick brains.     

SEPARATION OF APPARENT MULTIPLE FORMS OF HUMAN BRAIN CHOLINE ACETYLTRANSFERASE BY ISOELECTRIC FOCUSING

Abstract— Choline acetyltransferase (acetyl-CoA: choline O -acetyl transferase; EC 2.3.1.6; ChAc) purified from human brain (basal ganglia) and sciatic nerve were separated into apparent multiple enzyme forms by the method of isoelectric focusing (pH gradient 3-10) on acrylamide gel. A preparative separation of enzyme forms of human brain was accomplished by the column method, by using a sucrose gradient. When each separated form was re-electrofocused, only a portion of the ChAc activity was observed in its original pH region while more than one-half of the recovered activity for each fraction appeared at pH 7.8-8. Gel filtration and kinetic studies of separated forms indicated that the more acidic forms might be aggregates, while more basic forms might be configurational isomers. Human ChAc of sciatic nerve did not exhibit acidic forms on electrofocusing, but otherwise yielded an electrofocusing profile similar to that of human brain. ChAc of rabbit brain and sciatic nerve each exhibited only a single form at pH 7.1 ± 0.2. Although ChAc differs among species, the enzyme of brain and sciatic nerve of the same species cannot be clearly distinguished by electrofocusing.     

COMPARATIVE STUDIES ON THE DEGRADATION OF GABA and TAURINE IN THE BRAIN

Abstract— The degradation of taurine and GABA in mammalian brain was studied in vivo and in vitro. Small amounts of [³⁵S]isethionate (10–20 pmol/g brain wet weight) and [³⁵S]sulphate (about 2 pmol/g) were detected in mouse brain after intramuscular injection of [³⁵S]taurine. Taurine also produced isethionate in rat brain homogenates (about 20 nmol/h/g protein) and subcellular fractions (about 40 nmol/h/g protein in synaptosomes and about 300 nmol/h/g in mitochondria), but the reaction was not stimulated either by external electrical pulses or by the addition of various cofactors (NAD and NADP in both oxidized and reduced forms, riboflavin, glutathione. pyridoxal-5'-phosphate, ATP) to the incubation medium. [¹⁴C]GABA was readily metabolized to [¹⁴C]succinate both in vivo and in vitro. Isethionate formation activity was concentrated in the mitochondrial fraction, as was also GABA-T activity. Partially purified GABA-T from calf brain also slightly catalysed the formation of [³⁵S]isethionate (about 1.3 μmol/min/g protein) from [³⁵S]taurine. It appears that the slight formation of isethionate from taurine is coupled to GABA-T activity. The formation of isethionate from taurine is so small, that it apparently has no role in the control of the brain taurine pool.     

五味子科两个种的核型比较研究

本文报道二色五味子和盘柱五味子两种的染色体核型,均为首次报道．结果表明两种的核型公式相同,２ｎ＝２８＝２８ｍ,但根据Ｓｔｅｂｂｉｎｓ的核型不对称性的分类它们之间存在着明显的差异,二色五味子为１Ａ型;盘柱五味子为１Ｂ型。１Ｂ型是首次在被子植物中发现．也许它显示了原始类群中的一种进化特点。另外染色体相对长度组成表明二色五味子２ｎ＝２８＝１２Ｍ２＋１４Ｍ１＋２Ｓ;盘柱五味子２ｎ＝２８＝２Ｌ＋１２Ｍ２＋１２Ｍ１＋２Ｓ．由此南五味子属的核型较二色五味子进化。     

两种长臂猿染色体的C带和Ag－NORs的比较研究

本文对长臂猿属（Ｈｙｌｏｂａｔｅｓ）中白眉长臂猿（Ｈ．ｈｏｏｌｏｃｋ）２ｎ＝３８和白颊长臂猿（Ｈ．ｌｅｕｃｏｇｅｎｙｓ）２ｎ＝５２的染色体Ｃ带和Ａｇ－ＮＯＲｓ进行了比较研究。结果表明,两种长臂猿的Ｃ带核型中除多数染色体有着丝点Ｃ带外,一些染色体上还出现插入Ｃ带和着丝点Ｃ带弱化或减少现象;白眉长臂猿有全异染色质臂;白颊长臂猿有较多的端位Ｃ带。白眉长臂猿有两个Ａｇ－ＮＯＲｓ,而白颊长臂猿的Ａｇ－ＮＯＲｓ雌体有４个,雄体有５个,Ｙ染色体上有ＮＯＲ．本文对长臂猿的核型进化作了讨论。     

STUDIES ON THE INHIBITION OF BRAIN PHOSPHO-FRUCTOKINASE BY OLEATE AND THE DETERMINATION OF FATTY ACIDS IN NORMAL AND HYPOXIC BRAIN

Abstract— Oleate inhibited phosphofructokinase activity in the brain in a way which was similar to known surface-active protein denaturants. Experimental hypoxia produced an increase in the level of fatty acids in the microsomal, but not in the cytosol fraction of the brain. It is suggested that under hypoxic conditions the influence of fatty acids on the activity of phosphofructokinase (if any) is of non-specific character.     

黑龙江流域两种细鳞鲑的形态学比较及其分类地位初探

对比研究了分布于我国黑龙江流域具钝吻和尖吻两种形态特征的细鳞鲑,其主要形态学性状的显著差异达到种间分化水平.细鳞鲑属Brachymystax在中国应有两个种,分别为图们江细鳞鲑B.tumensis(具钝吻特征)和细鳞鲑B.lenok(具尖吻特征).     

TWO FORMS OF ALANINE AMINOTRANSFERASE IN RAT BRAIN DURING ONTOGENY

Abstract— Alanine aminotransferase activity in subcellular fractions of rat brains was investigated during ontogenic development. The activity rose from the prenatal period until adulthood, the highest increase being observed during the period of morphological metabolic and functional maturation of the brain. The rise of the total activity was due predominantly to a rise in the activity of the cytosblic enzyme; the activity of the mitochondrial enzyme did not change markedly during ontogeny. CI-ions and elevated temperature (55°C) inhibited the activity only of the mitochondrial enzyme. Raised temperature stimulated the activity of the cytosolic enzyme while CI-ions did not influence its activity. Our results indicate that 2 alanine aminotransferase isoenzlmes are already present in the rat brain in the prenatal period. It is assumed that the cytosolic enzyme is involved in the regulation of tissue glycol)sis and alanine formation, while the mitochondrial enzyme plays a role in the amino nitrogen transport between mitochondria and cytosol.     

COMPARATIVE BIOCHEMICAL STUDY OF TWO ALLELIC FORMS OF A GENE AFFECTING LEAF-SHAPE IN THE TOMATO

Through successive selfing of lanceolate, a leaf-shape mutant in the tomato, the 3 leaf-shape forms, namely, normal (La⁺/La⁺), lanceolate (La⁺/La), and homozygous lanceolate (La/La), were obtained in a uniform genetic background. The mutant allele lanceolate causes the increase in activities of the following oxidative enzymes: tyrosinase, laccase, peroxidase and catalase. The lanceolate gene exhibits a dosage effect with respect to these enzymes; the homozygous lanceolate shows the highest activity, heterozygous lanceolate is intermediate, and normal shows the lowest activity. The relative differences in activity of these enzymes between the 3 genotypes persist at all stages of development and in all organs examined.     

STUDIES ON THE MONOAMINE OXIDASE OF MONKEY BRAIN

Abstract— A study of the enzyme monoamine oxidase (MAO) was carried out in the monkey brain. From the monkey brain mitochondrial fraction a lysolecithin-soluble form of the enzyme (MAO_s and an insoluble form (MAO_p) were isolated. The latter required freezing, thawing and sonication for solubilization. Both these forms of MAO had identical electrophoretic mobilities, a pH optimum of 7 and comparable thermal stabilities. The enzyme which could not be solubilized and which remained membrane-bound also gave the same pH optimum of 7 and a similar thermal stability profile. Both MAO_s and MAO_p had comparable K _m values of 2.2 × 10⁻⁵ m and 5.0 ×^105- m respectively when using tyramine as substrate and 7.4 ×⁻⁵ M and 7.7 × 10⁻⁵ m respectively with benzylamine as substrate. The K _m values of the membrane-bound enzyme were 1.0 × 10"⁵m with tyramine as substrate 2.5 × m with benzylarnine as substrate. The MAO inhibitors, tranylcypromine, isocarboxazid and iproniazid inhibited both MAO_s and MAO_p to approximately the same extent. The extent of inhibition of the membrane-bound enzyme however, was relatively different with all three inhibitors. Immunodiffu-sion techniques using anti-MAO_p indicated the immunological identity among MAO_p, MAO_s and the mitochondrial fraction. Substrate specificity and substrate competition experiments as well as the use of the selective inhibitor pargyline indicated the presence of both the 'A' and 'B' type of activity in the MAO isolated from monkey brain.     

猕猴桃属植物生物学特征特性观测

观测了猕猴桃属４１个种或变种、变型及２个种间杂交后代的幼苗、成年植株、花器、果实及种子等的植物学特征及物候期、开花结果习性等生物学特性,为该属植物的系统发育、杂交育种选择亲本、定向培育以及制定相应的栽培技术措施等研究提供了科学依据．     

聚丙烯腈纤维固定化青霉素酰化酶性质的研究

将巨大芽孢杆菌（Bacillusmegaterium）青霉素酞化酶连接到聚丙烯腈纤维载体上,制成固定化青霉素酰化酶。其表现活力约为2000u／g。水解青霉素G的最适温度为50℃;最适PH为9．0;在PHS．5～10．3、温度50℃以下酶的活力稳定;表观米氏常数Ka为1．33×10-8mol／L;最大反应速度Vm为2．564mmol·min-1;苯乙酸为竞争性抑制剂,抑制常数为0．16mol／L。水解10％的青霉素G钾盐溶液,使用20批,保留酶活力80％。     

COMPARATIVE PEPTIDE MAPPING AND ISOELECTRIC FOCUSING OF ISOLATED SUBUNITS FROM CHICK EMBRYO BRAIN TUBULIN

The α- and β-subunits of chick embryo brain tubulin have been isolated under denaturing conditions and compared with respect to their molecular weight, amino acid composition, tryptic peptide maps, amide content and isoelectric focusing properties. An 8 M-Urea-containing polyacrylamide gel system with varying acrylamide concentrations was used for calculation of the retardation coefficients (K_R) of the tubulin subunits. A molecular weight of 53,000 was estimated for each subunit by comparison to K_R values for standard proteins. Amide contents of approx 41% of the carboxyl groups of α-tubulin and 48% of the carboxyl groups of β-tubulin were calculated using the average PI value, the pK_intrinsic for the ionizable side chains of the amino acids and the amino acid composition of each subunit. Comparative peptide maps of trypsin digested α- and β-tubulin demonstrated 16 peptides unique to each subunit and 23 peptides which comigrate. Both subunits give rise to multiple species on electrofocusing gels. The average isoelectric points for the α- and β-subunits are 5.4 and 5.2, respectively.     

COMPARATIVE STUDIES ON GLUTAMYL-tRNA SYNTHETASES ISOLATED FROM CYTOPLASM AND MITOCHONDRIA OF CALF BRAIN

Preparations of glutamyl-tRNA synthetase (EC 6.1.1.17) were isolated from cytoplasm and mitochondria of calf brain and purified by 14 and 9.5 times respectively. The effect of pH and that of the concentration of basic incubation mixture components on glutamyl-tRNA formation were estimated. The two preparations showed differences in response to optimum ration of Mg²⁺/ATP which is 6 for cytoplasmic system and 1 for mitochondrial system in aminoacylation reaction and a considerable difference in sensibility to concentration change of monovalent cations. Dithiotreitol not only protected both enzymatic preparations against thermal inactivation but even increased their activity.     

草珊瑚属两个新变种与海南草珊瑚的比较研究

对广东海南岛、广西、云南产的海南草珊瑚Sarcandra hainanensis(Pei)Swamy et Bailey进行形态学和茎的组织比较研究结果表明,Swamy等描述的海南草珊瑚是一个混杂的种群。本文对海南草珊瑚的描述作了修订,分出两个新变种:屏边草珊瑚S.hainanensis(Pei)Swamy etBailey var.pingbianensis C.Z.Qiao et Q.H.Zhang和陵水草珊瑚S.hainanensis(Pei)Swamy et Bailey var.lingshuinensis C.Z.Qiao et Q.H.Zhang.     

两种异养性鞭毛虫实验种群数量动态的比较研究

1999年4－8月从武昌东湖PFU样本中分离纯化了两种异养性鞭毛虫,对四种不同浓度Ceraphyl培养液中的种群增长进行了比较研究,结果表明这两种异养性鞭毛虫种群的数量动态显著不同,聚滴虫在四种浓度Ceraphyl培养液中均呈逻辑斯谛增长;而舞行波豆虫在四种浓度Ceraphyl培养液中的增长曲线均为抛物线。拟合组建了种群增长方程,并论证了方程可信度及其参数的生态学意义。     

改性酵母葡聚糖—CMG的结构特征

本文采用凝胶过滤色谱法,对两种不同工艺方法制备的羧甲基酵母葡聚糖(MA和MW)的分子量进行了测定。采用~(13)C-NMR光谱,研究了酵母葡聚糖和羧甲基葡聚糖的主链的连接方式和羧甲基在葡聚糖分子中的分布。研究结果发现,MA的分子量略大于MW,它们的分子量均在10~5数量级。酵母葡聚糖是以β-(1-3)连接为主的。羧甲基化取代主要发生在C_5位的羟基上。     

COMPARATIVE STUDIES ON RESPIRATION : V. THE EFFECT OF ETHER ON THE PRODUCTION OF CARBON DIOXIDE BY ANIMALS.

1. The experiments on frog tadpoles show that with 0.15, 0.37, and 0.55 per cent ether solutions there is a decrease in CO₂ output. The effect is reversible. With these concentrations the breathing movements and body movements remained normal during the experiment. In 3.65 and 7.3 per cent ether there is a decrease of respiration followed by an increase which in turn is followed by a decrease. The increase may reach about three times the normal rate. The increase in the CO₂ output is accompanied by the peeling of the skin. The effect is irreversible. 2. Experiments on an aquatic insect, Dineutes assimilis Aube, show that in 7.3 per cent ether there is a decrease followed by an increase which in turn is followed by a decrease. There is no apparent disintegration of structures in the organism accompanying the increase. The effect is irreversible. 3. The experiments on frog eggs with 7.3 per cent ether show a result similar to that found in aquatic insects. 4. Experiments on Fundulus embryos show that with 0.73 per cent ether there is a reversible decrease in the rate of CO₂ production. In 3.65 per cent ether there is a temporary decrease followed by an increase, after which the rate begins to fall off. In 7.3 per cent ether there is an immediate increase amounting to 307 per cent which is followed by a decrease. The increase in the 3.65 and 7.3 per cent ether is accompanied by irreversible changes leading to death. The decrease found in 0.73 per cent ether is not sufficient to cause narcosis, as is shown by experiments on which the same decrease is produced by lowering the temperature. 5. These experiments show that narcosis is not due to asphyxia. The action of anesthetics is due to some other cause than the effect on respiration. There is a difference between the animals studied and the plants described in this series of articles, since in animals the increase in the CO₂ output is accompanied by irreversible changes leading to death, while this is not necessarily the case in plants. The reversible (narcotic) action of ether on the animals studied was accompanied by a decrease in the carbon dioxide output; in plants this is not ordinarily the case. These facts are of considerable interest, but their interpretation must be left to future investigation.     

用相关分析法研究家兔两类膈神经单位电活动差异的起源

家兔25只,乌拉坦静脉麻醉(1g/kg),三碘季铵酚制动,人工通气,切断双侧颈迷走神经干。分离双侧膈神经,右侧记录神经干放电;左侧分离细束,同时记录一对单位的放电。共记录到36对单位。神经电活动经放大后输入磁带记录仪,备作脱机处理;或将信号放大、限幅后输入计算机,作连机处理。单纤维根据其放电时程同神经干放电的关系分为时相性单位(PU)和紧张性单位(TU)。分别在TU同TU之间、PU同PU之间、PU同TU之间作相关分析。 在总共36对膈运动神经单位对中,有21对的互相关直方图上出现有显著意义的中心峰,表明它们之间存在着同步化活动,是接受共同的中枢传入所致。其中8对为2PU,,11对为2TU,2对为1PU和1TU。同步化活动的类型有短时程同步化、宽峰同步化和高频振荡同步化三种。在同类单位对(2PU或2TU)与不同类单位对(1PU和1TU)出现同步化的频数之间作x~2检验,结果表明同类单位对中出现同步化的比例显著高于不同类的单位对。 据此,我们认为膈运动神经元紧张性单位和时相性单位放电特性的不同可能是由于它们接受不同的中枢支配所致。