固氮生化遗传学研究进展Ⅰ.

人类需要蛋白质食物。蛋白质可来自植物,也可来自动物,但最终还是来自植物。蛋白质由氨基酸组成。植物吸收土壤中氮化物同化成氨基酸,然后合成蛋白质。在耕作区为植物利用的氮有限,必须施加大量人工合成氮肥。近年来,世界能源危机,用当前高温高压方法合成氮肥受到很大限制。其实,地球上氮肥主要来源于生物。有些微生物可将空气中不能为植物直接利用的氮气转化为氨,称为生物固氮。固氮生物有自生固氮的克氏肺炎杆菌(K.pneumoniae)     

固氮生化遗传学研究进展Ⅱ(续)

二、共生固氮的生化遗传学共生固氮是固氮生物和宿主植物两者相互作用和协调的结果。前者将固定的氮供宿主植物合成氨基酸和蛋白质,后者将光合作用部分产物输送到根瘤,为细菌进行固氮提供能量。共生固氮的生化遗传学更为复杂。涉及到细菌和植物各自的遗传学和它们之间的相互作用,其研究比较困难。但由于分子     

联合固氮研究进展

联合固氮研究进展李久蒂安千里（中国科学院植物研究所,北京１０００９３）ＡＤＶＡＮＣＥＳＩＮＡＳＳＯＣＩＡＴＥＤＮＩＴＲＯＧＥＮＦＩＸＡＴＩＯＮＲＥＳＥＡＲＣＨＬｉＪｉｕ－ｄｉＡｎＱｉａｎ－ｌｉ（ＩｎｓｔｉｔｕｔｅｏｆＢｏｔａｎｙ,ＣｈｉｎｅｓｅＡｃ...     

海洋生物固氮研究进展

海洋生物固氮因可以支持初级生产所需的氮而在全球碳氮循环中具有重要作用。从二十世纪九十年代分子生物学和15N2同位素示踪法应用于固氮研究领域以来, 逐渐发现了单细胞固氮蓝藻和异养固氮细菌的重要性, 是近年来海洋固氮研究领域的最大进展之一, 表明以前基于束毛藻为主要固氮生物估算的固氮量可能低估了生物固氮在全球海洋生物地球化学循环中的地位。另一方面, 传统的海洋生物固氮研究仅局限于热带亚热带的寡营养盐区域, 对高营养盐区域如上升流、河口等高营养盐区域较少关注, 因此有必要对这些区域的生物固氮进行重新评估和再认识。综述了国际固氮研究的最近进展, 主要包括固氮生物多样性及分布特征、生物固氮的限制性因素、研究方法以及存在的问题。同时综述了南海生物固氮方面的最新进展和问题。     

人类生化遗传学和疾病

人类生化遗传学是一门边缘学科;它研究人类遗传物质的生化性质及其对人体蛋白质合成和代谢的调节控制;从而揭示人类遗传性状的发育和遗传疾病的生化本质。     

固氮螺菌的固氮分子调控研究进展

本文对巴西固氮螺菌周氨基因的结构和调控进行综述。其固氮基因的调控可分为两种水平：通过DRAT-DRAG系统的翻译后水平和通过NifA蛋白的转录水平。通过NifA活性进行调控的机理目前尚不明了。     

联合固氮的研究进展

1975年,Dbereiner实验发现与禾本科植物联合共生的固氮菌并提出根际联合固氮的概念。近年来,随着一些新的研究手段包括化学分析、遗传工程、分子生物学、免疫学等方法的运用,推进了联合固氮领域的研究深度。综述了近年来发现的联合固氮菌的种类;联合固氮体系的形成过程（趋化、结合和侵入）;影响联合固氮的主要因素：自然条件、土著微生物的竞争、植物基因型差异和环境条件的变化、结合态氮（氨、亚硝酸盐、硝酸盐等）和氧。并从固氮联合作用测定方法、联合固氮菌的资源筛选、联合固氮工程菌的研究、联合固氮分子生态学研究方法4个方面,论述了联合固氮的研究现状。     

根瘤菌共生固氮的遗传学研究(一)

根瘤菌是一种重要的固氮微生物,由于它和植物形成独特的共生关系,所以可固定较大量的氮,据估计每年出于根瘤菌共生所固定的氮量可达139×10~6吨之多,约占地球上正个固氮总量的四分之一。在农业上根瘤菌共生固氮也是一个重要的氮素来源。     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Synthesis and antimicrobial studies of hydrazone derivatives of 4-[3-(2,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid and 4-[3-(3,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid

Microbial resistance to antibiotics is an unresolved global concern, which needs urgent and coordinated action. One of the guidelines of the Centers for Disease Control and Preventions (CDC) to combat antibiotic resistance is the development of new antibiotics to treat drug-resistant bacteria. In our effort to find new antibiotics, we report the synthesis and antimicrobial studies of 30 new pyrazole derivatives. These novel molecules have been synthesized by using readily available starting materials and benign reaction conditions. Some of these molecules have shown activity with MIC values as low as 0.78?µg/mL against four bacterial strains; Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, and Acinetobacter baumannii. Furthermore, active molecules are non-toxic to mammalian cell line.