Composition and Distribution of Free Amino Acids in Flatpea (Lathyrus sylvestris L.) as Influenced by Water Deficit and Plant Age

Drought-stressed flatpea (Lathyrus sylvestris L.) plants from8 to 22 weeks old were analysed for nitrogen, soluble proteinand free amino acids. An increase in nitrogen and free aminoacid concentrations and a decrease in soluble protein levelwere observed in roots of plants up to 16 weeks old. The cumulativeconcentration of free amino acids increased with drought stress.Tissue concentrations of 2, 4-diaminobutyric acid (1.6–2.6%of the dry weight) were highest in leaves. Levels increasedsteadily, nearly doubling, in leaves and stems between weeks10 and 16. Levels in drought-stressed leaves were, on average,11.9% higher than those of controls. Estimated concentrationsof a mixture of 4-aminobutyric acid and an unknown amino acidwere highest in stems, increased in this tissue with age andtended to increase in stems and leaves and decrease in rootsin response to water deficit. Levels of the mixture of homoserineand another unidentified amino acid were not influenced by ageor water status of the plants. Root concentrations of asparagine,arginine, glutamine, aspartate, and another prominent, unidentifiedamino acid increased with plant age and reached a peak at thetime of flowering (14 to 18 weeks). Only the concentration ofthe unknown compound was elevated following drought stress.Concentrations of valine, isoleucine, leucine, phenylalanine,and methionine also increased during this period and were elevatedin drought-stressed plants. Proline levels increased with plantage and drought stress, but proline accounted for only about10% of the total free amino acids in the drought-stressed plants. Key words: 2, 4-Diaminobutyric acid, drought, flatpea     

厚壳贻贝whirlin类贝壳基质蛋白的重组表达与功能分析

贝壳历来是生物工程和材料学研究的重要对象。贝壳中的贝壳基质蛋白质在贝壳的形成与发育过程中具有重要的调控作用。Whirlin类蛋白质(Whirlin-like protein,WLP)是一种从厚壳贻贝(Mytilus coruscus)中鉴定的新型贝壳基质蛋白质。序列分析结果显示,该蛋白质含有PDZ(postsynaptic density/Discs large/Zonula occludens)结构域,而该结构域对贝壳生物矿化的影响目前尚无报道。为深入了解WLP在贝壳形成中对碳酸钙晶体的影响,在序列分析基础上,采用密码子优化结合原核重组表达,获得其重组表达产物后,开展了重组WLP对碳酸钙晶体形貌及晶型的影响研究,结晶速度抑制以及碳酸钙晶体结合分析。分析结果表明,重组WLP能诱导文石型碳酸钙晶体的形貌和方解石型碳酸钙晶体的晶型发生改变;同时重组WLP对碳酸钙晶体具有结合作用,且能抑制碳酸钙晶体的结晶速度。上述结果表明,WLP对贝壳的形成及发育具有重要影响,并可能在贝壳肌棱柱层的形成中发挥了重要作用。     

艾菲属吸虫一新种（复殖目：鳞肉科）

艾菲属(Aephnidiogenes)吸虫在我国为首次报道,文中记述了采自海南岛一种胡椒鲷(Plectorhynchus pictus)体内的海南艾菲吸虫,新种(Aephnidiogenes hainanensis sp. nov.),对其形态特征进行了描述,并与相近种作了比较。虫体11.641—17.425mm,卵巢为不规则三角形,卵子66—69×33—45μm。     

长非编码RNA PVT1与消化系统肿瘤

长非编码RNA（long non-coding RNAs, lncRNAs）在肿瘤发生、发展进程中承担重要角色,是近年来的研究热点之一。大量研究表明,浆细胞瘤变异易位基因1（plasmacytoma variant translocation 1, PVT1）可通过多种分子机制参与调控消化系统肿瘤的增殖凋亡、迁移侵袭、细胞自噬、血管生成、多药耐药及肿瘤代谢等过程,从而发挥致癌作用。本文主要就PVT1在消化系统肿瘤中的表达水平变化,及其与临床病理特征和预后的关系,以及PVT1对消化系统肿瘤的致癌作用机制和多药耐药机制等研究进展作一综述。     

过氧化心肌线粒体产生的脂类自由基及（－）－EGCG的抑制作用

本文利用ＥＳＲ技术研究了心肌线粒体酶修饰下的脂质过氧化和脂类自由基,以及（－）－ＥＧＣＧ的抑制作用。结果表明：４－ＰＯＢＮ能捕集ｌｉｐｏｘｙｇｅｎｇｓｅ诱发心肌线粒体产生的自由基,得到６条线谱的脂类自由基和４条线谱捕集物,（－）－ＥＧＣＧ对该体系中使用的１ｉｐｏｘｙｅｎａｓｅ活性无影响,对所产生的自由基有明显的清除作用,并呈量效关系。对脂质过氧化的抑制作用,在本试验浓度范围内随浓度增加变化不大,最大抑制率约２０％。     

玉米叶绿体atpB及atpE基因在大肠杆菌中的表达

本实验构建了在大肠杆菌中能表达玉米叶绿体ＣＦ１完整β亚基、缺失Ｎ端２３个氨基酸残基的β亚基以及完整ε亚基的表达质粒。ＳＤＳ－聚丙烯酰胺凝胶电泳及Ｗｅｓｔｅｒｎｂｌｏｔ实验表明,在分别含这些表达质粒的细菌中β、ε亚基蛋白的合成量在诱导３ｈ后即达到饱和,其含量各占细菌体总蛋白的１０％左右。这些表达产物在细菌体中形成不溶性的包含体。可通过对菌体蛋白的分级分高,将表达产物溶于５ｍｏｌ／Ｌ的尿素溶液中。     

湖羊瘤胃微生物GH9家族葡聚糖酶基因IDSGLUC9-25的表达与功能表征

【目的】葡聚糖酶是饲用添加剂的重要成分,本研究旨在从湖羊消化道微生物中挖掘性质优良的GH9家族葡聚糖酶基因,用于研发新型饲用酶制剂。【方法】从湖羊瘤胃微生物cDNA中扩增IDSGLUC9-25基因,在大肠杆菌中进行异源表达,对重组蛋白进行诱导表达和纯化,研究重组蛋白的酶学性质和底物水解模式。【结果】IDSGLUC9-25基因编码527个氨基酸,包含一个CelD_N结构和一个GH9家族催化结构域;重组蛋白rIDSGLUC9-25分子量约为62.7 kDa,最适反应温度和pH分别为40℃和6.0,在30-50℃下活性较高,在pH 4.0-8.0范围内能够保持较高的稳定性,经pH 4.0-8.0缓冲液处理1 h后残余活性均大于90%;底物谱分析表明,rIDSGLUC9-25能催化大麦β-葡聚糖、苔藓地衣多糖、魔芋胶和木葡聚糖,比活性分别为(443.55±24.48)、(65.56±5.98)、(122.37±2.85)和(159.16±7.73) U/mg;利用薄层色谱法(thin layer chromatography, TLC)和高效液相色谱法(high performance liquid chromatography, HPLC)分析水解产物发现,rIDSGLUC9-25降解大麦葡聚糖主要生成纤维三糖(占总还原糖64.19%±1.19%)和纤维四糖(占总还原糖26.24%±0.12%),催化地衣多糖主要生成纤维三糖(占总还原糖78.46%±0.89%)。【结论】本研究报道了一种来自密螺旋体属细菌的内切β-1,4-葡聚糖酶IDSGLUC9-25 (EC 3.2.1.4),能高效催化多糖底物生成纤维三糖和纤维四糖,为研发饲用酶制剂和制备低聚寡糖建立基础。     

G2 phase cell cycle disturbance as a manifestation of genetic cell damage

The predominant cell cycle change induced by X-rays and clastogens in peripheral blood mononuclear cells is the accumulation of cells in the G2 phase of the cell cycle. We show that this accumulation consists of cells that are either delayed or arrested within the G2 phase. Since both X-rays and DNA crosslinking chemicals are known to damage DNA, the G2 phase inhibition caused by these agents is thought to be one of the primary manifestations of (unrepaired) DNA damage. This interpretation is supported by two additional findings. (1) Older individuals have elevated baseline levels of mononuclear blood cells that are delayed and/or arrested in the G2 phase of the cell cycle. This coincides with the increased chromosomal breakage rates reported for older individuals. (2) Irrespective of their age, individuals with inherited genetic instability syndromes (such as Fanconi anemia and Bloom syndrome) exhibit elevated G2 phase cell fractions. We show that the method used to detect such induced or spontaneous cell cycle changes, viz. BrdU-Hoechst flow cytometry, is a rapid and highly sensitive technique for the assessment of genetic cell damage.Dedicated to Professor Ulrich Wolf on the occasion of his 60th birthday