Genetic aspects of increase in rat liver aldehyde dehydrogenase induced by phenobarbital

In the supernatant fraction of homogenized rat liver, the activity of aldehyde dehydrogenase that is dependent on nicotinamide adenine dinucleotide (E.C. 1.2.1.3) is increased up to tenfold after administration of phenobarbital for 3 days. The effect is genetically controlled and is inherited as an autosomal dominant characteristic. The mechanism is apparently unrelated to other druginduced increases in enzyme activity such as that which occurs in the hepatic microsomal systems for drug metabolism.     

Protein synthesis: its control in erythropoiesis

Erythropoiesis in the fetal mouse provides a model to study several important aspects of the regulation of cell differentiation and differentiated protein synthesis. Changes in the patterns of hemoglobins formed during fetal and postfetal development are shown to be associated with the substitution of the liver erythroid cell line. In the course of differentiation of yolk sac erythroid cells there are at least two classes of proteins distinguishable with respect to dependence on continued RNA formatoin. The bulk of nuclear proteins, "nondifferentiated" proteins, appear to be dependent on relatively short-lived messenger RNA while synthesis of differentiated proteins, the hemoglobins, proceeds on relatively stable molecules of messenger RNA. Hemoglobin formation occurs in those cells which are actively synthesizing DNA and dividing. On the average, two to three cell divisions may occur after the formation and stabilization of the messenger RNA for globin. Yolk sac erythropoiesis, at least from day 10 of gestation, is unresponsive to erythropoietin. By comparison, in fetal liver erythropoiesis, the hormone, erythropoietin, acts selectively on the most immature erythroid cell precursor to induce differentiation, cell replication, and hemoglobin formation. The erythropoietin responsive cell in the liver is apparently differentiated from the progenitor, pluripotential stem cell and committed to erythroblast formation and hemoglobin synthesis on exposure to the hormone. The initial effects of erythropoietin on macromolecular synthesis are to stimulate RNA synthesis, which temporally is followed by cell replication and the increase in hemoglobin formation. During liver erythropoiesis, there appears to be a transition from hemoglobin synthesis dependent on RNA formation to hemoglobin synthesis directed by relatively stable messenger RNA.     

含S氨基酸对肉仔鸡解毒作用的研究

通过向饲料中添加黄曲霉毒素（AF）和两种含S氨基酸－蛋氨酸及半胱氨酸，根据生化指标的测定情况，研究蛋氨酸及半胱氨酸对雏鸡黄曲霉毒素中毒的解毒作用。结果表明：口服AF组肉仔鸡白细胞数目及血清GPT水平明显升高，而红细胞数目以及肝脏GSH水平和肝脏DNA合成量减少。补加蛋氨酸或半胱氨酸则可减轻AF对雏鸡肝脏的损伤，使上述各指标均与对照组无明显差异。     

New light-sensitive cofactor required for oxidation of succinate by Mycobacterium phlei

Irradiation of the electron transport particles of Mycobacterium phlei with light at a wavelength of 360 manometers resulted in a loss of oxidase activities of succinate and the reduced form of nicotinamide adenine dinucleotide. The lesion in the two pathways caused by irradiation of the particles differs. The succinoxidase pathway was more labile to irradiation than the pathway linked to nicotinamide adenine dinucleotide. Restoration of succinoxidase activity (up to 50 to 60 percent) occurred on addition of a thermostable, water-soluble material obtained from Mycobacterium phlei cells or with an extract of mitochondria from boiled rat liver. Other known cofactors, such as flavine adenine dinucleotide, flavine mononucleotide, benzo- and naphthoquinones, as well as sulfhydryl agents, failed to restore succinoxidase activity after irradiation. Water-soluble material from Mycobacterium phlei appears to function between the flavoprotein and cytochrome b on the succinoxidase pathway. In contrast to the requirements for restoration of the pathway linked to nicotinamide adenine dinucleotide, restoration of succinoxidase does not occur with quinones or other cofactors such as flavine adenine dinucleotide.     

提高豆科植物蛋氨酸含量的基因工程途径

豆科植物普遍缺乏蛋氨酸和半胱氨酸这类含硫氨基酸,影响了其营养品质。采用基因工程手段改造内源蛋白基因,克隆异源高蛋氨酸蛋白基因,人工合成氨基酸平衡的蛋白基因,以及改造或过表达氨基酸代谢通路中的关键酶基因,然后通过转基因手段转化豆科植物,会使蛋氨酸含量均有不同程度提高。另外,利用高蛋氨酸的近缘种质资源进行有性杂交育种,通过化学诱变培育高蛋氨酸突变株,也可获得一些高蛋氨酸新品系。通过对这些方法的比较分析,提出了提高蛋氨酸丰富蛋白表达量和蛋氨酸合成量两方面相结合的研究思路,为豆科植物品质改良研究提供参考。     

Hyperoxaluria in L-glyceric aciduria: possible pathogenic mechanism

The effect of hydroxypyruvate on synthesis of oxalate and glycolate from glyoxylate was studied in in vitro preparations from normal human erythrocytes and leukocytes, rat liver, and with purified lactate dehydrogenase from beef heart. In the presence of reduced nicotinamide adenine dinucleotide, hydroxypyruvate stimulated the oxidation of glyoxylate to oxalate and decreased the reduction of glyoxylate to glycolate. These findings may explain the hyperoxaluria seen in L-glyceric aciduria (type II primary hyperoxaluria).     

Specialization of rabbit reticulocyte transfer RNA content for hemoglobin synthesis

The amount of acceptance of each amino acid per absorbancy unit of rabbit reticulocyte transfer RNA was determined. The results were compared with the amino acid composition of rabbit hemoglobin and with a similar determination of the transfer RNA content of rabbit liver. The histidine and isoleucine transfer RNA content of reticulocytes is specialized for the synthesis of hemoglobin, in which histidine is unusually common and isoleucine unusually scarce compared to most proteins.     

Messenger RNA patterns in rat liver nuclei before and after treat-ment with growth hormone

Like cortisol, growth hormone enhances RNA synthesis in rat liver nuclei. However, DNA-RNA hybridization experiments show that the application of growth hormone does not stimulate the formation of new species of messenger RNA. The latter phenomenon was observed after treatment with cortisol.     

Breakdown of rat-liver ergosomes in vivo after actinomycin inhibition of messenger RNA synthesis

Ribosomes isolated from rat liver occur predominantly in the form of aggregates (ergosomes) corresponding to multiples of 73S particles held together by messenger RNA. After injecting rats with actinomycin, these aggregates gradually break down in vivo to 73S monomers and 113S dimers. We conclude that the observed breakdown results from the degradation of messenger RNA and the prevention by actinomycin of the synthesis of new messenger RNA.     

Methionine adenosyltransferase deficiency: new enzymatic defect associated with hypermethioninemia

A specific deficiency of methionine adenosyltransferase has been demonstrated in the liver of an infant with hypermethioninemia. Since the enzymatic activity was below that in fetal liver and the metabolic abnormality has persisted (the infant now being 1 year of age), there is probably a genetic mutation. Mass screening for hypermethioninemia may uncover more such cases.     

固醇调节元件结合蛋白-1c在肝脂肪合成中转录调节

固醇调节元件结合蛋白 -1c(SREBP -1c)是脂肪合成基因的重要转录调节因子 ,又称脂肪细胞决定和分化因子 1(AdipocyteDetermi nationandDifferentiationfactor -1,ADD1) ,它是动物肝脏中主要的转录物 ,主要调节动物脂肪合成和葡萄糖代谢相关基因的表达。研究发现 ,SREBP -1c的过度表达与肝脏等非脂肪组织的脂质积聚相关。SREBP -1c调节体内的脂肪合成主要是通过改变自身的mRNA水平来实现的 ,即生脂酶的转录调节是由SREBP- 1cmRNA的数量控制的。另一方面 ,LXRs、胰岛素、胰高血糖素等因素对SREBP- 1c的转录有调节作用。     

猪肝脏总RNA快速提取方法

采用CTAB法和改良的Trizol法提取贵州从江香猪(Sus scrofa domestica)新鲜肝脏的总RNA,通过紫外分光光度法和凝胶电泳检测RNA质量。结果表明,改良的Trizol法提取的总RNA的纯度高,完整性好,优于CTAB法。且改良的Trizol法提取的猪肝脏总RNA可用于RT-PCR等后续分子生物学操作。     

不同方法提取狗脊蕨叶片总RNA的比较分析

[目的]为构建狗脊蕨叶cDNA文库,保存珍贵基因资源,克隆和研究与有效成分合成相关的基因等提供技术参考。[方法]以狗脊蕨叶片为材料,采用CTAB法、一步法、酚-SDS法和RNA试剂盒提取分离法提取总RNA,通过比较分析确定最优方法。[结果]这4种方法都能提取出182、8 S的RNA,但CTAB法和试剂盒提取分离法的总RNA质量较高,CTAB法还提取出清晰的5S RNA。一步法和SDS法带型模糊,有降解现象。CTAB法提取的狗脊蕨叶片总RNA质量较好,28S1、8S和5S条带清晰,且无明显降解。CTAB提取法OD260/OD280的值在1.93~2.06,试验中其OD260/OD280值为2.012,接近2.0,纯度较高。一步法和SDS法OD260/OD280>2.0,试剂盒法OD260/OD280<2.0。[结论]CTAB法适合提取的狗脊蕨叶片总RNA,质量较好,可用于cDNA合成、文库构建等后续分子生物学试验。     

Radioisotope uptake as a measure of synthesis of messenger RNA

Exogenously supplied radioactive uracil (or guanine) enters the intracellular pools of RNA precursors in Escherichia coli only as nucleotides are removed from these pools by net synthesis of RNA. Consequently uptake of uracil over a short period does not measure the sum of the synthesis of all forms of RNA, unstable and stable, as is often supposed. Uptake of uracil during changing conditions of growth may be influenced by changes in types of RNA's being made; under such conditions that no stable RNA is being made, the synthesis of unstable forms may be greatly underestimated.     

小鼠肝再生过程中脂质代谢相关通路中基因的表达谱变化

[目的]研究肝再生过程中肝脏内脂质代谢通路相关基因的表达谱变化。[方法]建立CC l4诱导肝再生小鼠模型,从小鼠肝组织中提取总RNA,通过微阵列基因芯片技术检测在不同肝再生期间脂质代谢通路相关基因的表达变化,并进行具体功能分析。[结果]肝再生过程中,有98个脂质代谢相关基因的表达水平发生了变化,根据这些基因表达的变化趋势可以分为8组。整体上看,基因表达前期表现为抑制,后期表现为上调。其中,脂肪酸的合成通路基因表达以上调为主,分解代谢通路变化并不明显;大多数胆汁酸合成通路基因在4.5天之前表现为抑制,在4.5天和7天时表现为上调。[结论]肝再生过程中,脂质代谢相关通路间的基因表达变化并不一致,这些数据为进一步研究脂质代谢相关通路对肝再生的调控作用提供了明确的基因范围。     

甘薯茎总RNA的简易高效提取方法

介绍了一种快速有效的提取甘薯[Ipomoea Batas(L.)Lam]茎总RNA的简易方法,无需特殊试剂和贵重的仪器设备,可有效的去除甘薯中的多酚、多糖类物质.所提取的RNA经过甲醛凝胶电泳和紫外线分光光度计分析,RNA的质量较高,基本没有降解,可直接用于cDNA合成、Northern杂交等多种分子生物学实验.     

蛋氨酸铁螯合物的制备及其性质鉴定

本文介绍了蛋氨酸铁螫合物的制备方法,并用红外光谱、核磁共振、蛋氨酸与铁的摩尔定量比、溶解度分析等方法论证了制得的产物确为蛋氨酸铁螫合物。     

Rapid switching of plant gene expression induced by fungal elicitor

The pattern of messenger RNA synthesis in suspension-cultured bean cells (Phaseolus vulgaris L.) was analyzed by blot hybridization and in vitro translation of newly synthesized messenger RNA. The RNA was separated from preexisting RNA by organomercurial affinity chromatography after in vivo labeling with 4-thiouridine. The elicitor induced the synthesis of messenger RNA's encoding phenylalanine ammonia-lyase, chalcone synthase, and chalcone isomerase, three enzymes of phenylpropanoid metabolism involved in the synthesis of isoflavonoidderived phytoalexins. This is part of a rapid and extensive change in the pattern of messenger RNA synthesis directing production of a set of proteins associated with expression of disease resistance.     

小鼠肝再生过程中脂质代谢相关通路中基因的表达谱变化

1材料与方法 1．1材料 试验动物：9周龄的雄性C57BIV6小鼠，自由采食和饮水，每天光照12h，黑暗12h。试剂：TRIzol试剂（Invitrogen）；RNeasy Total RNA Mini Kit（Qiagen）；基因芯片Genechip mouse genome 43020（Affymetrix）；17启动子引物序列（Affymetrix）。