Polypeptide synthesis in sea urchin embryogenesis: an examination with synthetic polyribonucleotides

After fertilization of the sea urchin egg the rate of protein synthesis by a cell-free ribosomal system increases markedly. This increase can be attributed to newly synthesized messenger RNA, since (i) the rate of polypeptide synthesis elicited by synthetic messenger polyribonucleotides changes only slightly after fertilization, and (ii) the enzymes for the formation of amino acyl transfer RNA's of phenylalanine and leucine and the polymerization of polypeptide are in excess in the unfertilized egg. Polypeptide synthesis has been characterized in development to the gastrula stage.     

Changes of chlorogenic acid content and its synthesis-associated genes expression in Xuehua pear fruit during development

According to synthetic pathway of plant chlorogenic acid(CGA),the expression patterns of genes encoding enzymes that are associated with CGA synthesis were studied in normally developed Xuehua pear fruit. The study demonstrated that CGA content in peel and flesh of Xuehua pear decreased as fruit development progressed,with a higher level in peel. The expression levels of PbPAL1,PbPAL2,PbC3H,PbC 4H,Pb4CL1,Pb4CL2,Pb4CL6,PbHCT1 and PbHCT3 genes decreased in fruit,which was consistent with the pattern of variation in CGA content. That indicated that these genes might be key genes for influencing fruit CGA synthesis in Xuehua pear. However,Pb4CL7 gene expression profile is not consistent with variation of CGA content,hence,it may not be a key gene involved in CGA synthesis.     

植物花青素生物合成途径相关基因研究进展及其基因工程修饰

对植物花青素生物合成及调控基因的研究进展、基因工程在调控花青素合成途径中的应用进行了综述。植物花青素生物合成属次生代谢途径,对该途径关键酶基因的调控可降低或提高目标化合物的产量,可通过调控植物次生代谢的方式对植物进行遗传改良。对植物通过积累花青素来适应紫外线辐射、防卫害虫及真菌侵害的分子机制进行研究,有助于培育抗病、抗逆的植物新品种。     

钾营养水平对番茄氮素代谢的影响

研究了不同水平的钾营养对番茄氮素代谢的影响,结果表明：钾素能明显促进蛋白质合成,防止蛋白质的水解。K＋作为酶的活化剂能促进植株体内硝酸还原酶活性等有关酶活性促进促进硝酸盐的转化,也能促进核酸的合成代谢,加快信息传递和促进蛋白质合成,减少蛋白质的水解。在适钾条件下,蛋白氮含量高而非蛋白氮含量明显降低。     

Chemical and spectroscopic evidence for an FeV-oxo complex

Iron(V)-oxo species have been proposed as key reactive intermediates in the catalysis of oxygen-activating enzymes and synthetic catalysts. Here, we report the synthesis of [Fe(TAML)(O)]- in nearly quantitative yield, where TAML is a macrocyclic tetraamide ligand. Mass spectrometry, M?ssbauer, electron paramagnetic resonance, and x-ray absorption spectroscopies, as well as reactivity studies and density functional theory calculations show that this long-lived (hours at -60 degrees C) intermediate is a spin S = 1/2 iron(V)-oxo complex. Iron-TAML systems have proven to be efficient catalysts in the decomposition of numerous pollutants by hydrogen peroxide, and the species we characterized is a likely reactive intermediate in these reactions.     

油菜角果开裂敏感性形成的研究

从油菜角果发育过程中角果含水量、乙烯合成速率、外切 ＰＧ 酶和内切纤维素酶活性,以及角果裂区切片观察等方面研究了角果开裂敏感性形成的原因⒚花后５０ ｄ 的角果果柄端壳状果瓣和线状果瓣间的裂区薄壁细胞膨大,在高倍光学显微镜下可见胞间空隙开始形成⒚此前６ ｄ 内乙烯合成速率迅速上升并出现第二次合成高峰,与之同步发生外切 ＰＧ酶和内切纤维素酶活性急剧上升,而乙烯合成第二高峰出现于角果含水量低于８０％ 以下⒚由此看来,角果失水引起乙烯合成第二高峰出现,从而导致水解酶活性上升,最终导致果瓣裂区薄壁细胞膨大,分离和胞间空隙形成及角果开裂敏感性产生⒚     

葡聚六糖诱导草莓抗叶枯病对叶片防御酶系活性的影响

感染叶枯病的草莓经喷施人工合成的植物抗病性诱导剂葡聚六糖后,提高了草莓叶片中的苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和多酚氧化酶(PPO)3种防御酶的活性.以0.5%的葡聚六糖稀释50倍液,诱导间隔期为7d,连续诱导3次的效果较好.     

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。     

Biosensors developments and potential applications in the agricultural diagnosis sector

There has been a phenomenal growth in the field of biosensor development in recent years with emerging applications in a wide range of disciplines, including medical analysis, food and the environment. The increase in the number of analytes requiring monitoring and others that require control, and the need for high sensitivity, speed, and accuracy of analytical measurements have stimulated considerable interest in developing sensors as diagnostics tools. A range of molecules with biorecognition powers are available naturally such as antibodies, enzymes, cell receptors and nucleic acids and are used as the sensing receptors in biosensors. The combined approaches of computer (molecular) modelling and combinatorial synthesis or molecularly imprinted polymers are undertaken today as a new method to produce synthetic receptors that can be used in sensor development. A wide range of transducers is also feasible to fulfil the rapid monitoring needs of the diagnostic market. Biosensors can also be incorporated into simple-to-use instruments as an on-line monitoring device or a one-shot sensor. This paper deals with recent developments in biosensors and their potential use in the agricultural diagnostic market.     

荔枝果皮花青苷合成与相关酶的关系研究

以‘妃子笑’荔枝为试材,研究果实成熟过程中,果皮中花青苷含量及其生物合成相关的苯丙氨酸解氨酶(PAL)、查儿酮异构酶(CHI)、二氢黄酮醇还原酶(DFR)和类黄酮糖基转移酶(UFGT)的酶活性变化,同时研究套袋和生长调节剂对花青苷合成和相关酶活性的影响。结果表明,在4种酶中只有UFGT活性与荔枝果皮花青苷合成关系密切。UFGT活性的变化与花青苷含量的变化趋势吻合;随着‘妃子笑’果皮中UFGT活性的增加,花青苷含量上升;套袋处理抑制UFGT活性的同时也抑制花青苷的合成,除袋后UFGT活性和花青苷含量都迅速增加;6-BA处理抑制UFGT酶活性的同时也抑制花青苷合成,ABA和茉莉酸处理提高了UFGT酶活性的同时也促进了花青苷的合成。     

A thiolate-ligated nonheme oxoiron(IV) complex relevant to cytochrome P450

Thiolate-ligated oxoiron(IV) centers are postulated to be the key oxidants in the catalytic cycles of oxygen-activating cytochrome P450 and related enzymes. Despite considerable synthetic efforts, chemists have not succeeded in preparing an appropriate model complex. Here we report the synthesis and spectroscopic characterization of [FeIV(O)(TMCS)]+ where TMCS is a pentadentate ligand that provides a square pyramidal N4(SR)apical, where SR is thiolate, ligand environment about the iron center, which is similar to that of cytochrome P450. The rigidity of the ligand framework stabilizes the thiolate in an oxidizing environment. Reactivity studies suggest that thiolate coordination favors hydrogen-atom abstraction chemistry over oxygen-atom transfer pathways in the presence of reducing substrates.     

Computer-assisted analysis in organic synthesis

The planning of alternative routes for the synthesis of complex organic molecules has been facilitated by the formulation of guiding strategies that can be applied to a broad range of problems. Analysis of organic synthesis can be carried out in the retrosynthetic direction, opposite to the actual process of chemical synthesis, or bidirectionally, that is, as a combined retrosynthetic and synthetic search. An interactive computer program is described which utilizes the general strategies of retrosynthetic analysis and an appropriate database to generate pathways of chemical intermediates for chemical synthesis of a particular target structure. Computer graphics and standard chemical structures are used for man-machine communication.     

苄星邻氯青霉素的研制

对苄星邻氯青霉素的合成,鉴定与含量测定进行了研究,经红外光谱鉴定证实合成品与苄星邻氯青霉素标准品一致,用标准的分析方法测得合成品中苄星邻氯青霉素和二苄基乙二胺的含量均符合1985年版英国兽医药典的规定,试验结果表明本品可以作为一种新的抗菌药物用于奶牛干奶期乳房炎的防治.     

ANTIGENS AND ENZYMES MADE INSOLUBLE BY ENTRAPPING THEM INTO LATTICES OF SYNTHETIC POLYMERS

Biologically active, insoluble products have been prepared from soluble antigens or enzymes by entrapping them into the lattice of an insoluble, highly cross-linked synthetic polymer as it forms. Antigens, made insoluble, removed quantitatively certain or all antibiotics from complex mixtures. Seven enzymes so treated are described.     

Chromatid breakage: cytosine arabinoside-induced lesions inhibited by ultraviolet irradiation

Exposure to ultraviolet light can reduce the frequency of chromatid breaks induced by cytosine arabinoside in the DNA synthetic and post-DNA synthetic phases of the cell cycle. This effect can be correlated temporally with a decrease in the uptake of tritiated thymidine after ultraviolet treatment, implying that the genesis of such breakage is intimately related to DNA synthesis and that such synthesis is not confined to the DNA synthetic phase.     

脐橙果实糖积累与蔗糖代谢相关酶关系的研究

通过对“罗伯逊”脐橙果实发育过程中糖含量以及蔗糖代谢相关酶———蔗糖合成酶 (SS)和蔗糖磷酸合成酶(SPS)活性的测定 ,结果表明 :SS合成与分解方向的活性变化趋势相似 ,SS分解方向活性在果实的整个发育期的两次回升 ,分别是SPS和SS合成方向的活性上升阶段 ,它通过调节果实内蔗糖浓度来影响果实的库强 ;SPS和SS合成方向分别是花后 15 0d之前和花后 15 0d之后影响果实糖积累的主要酶 ,SS分解方向则是通过调节果实的库强来影响糖积累     

植物油脂合成调控与遗传改良研究进展

植物种子油脂储存的主要形式是三酰甘油。在植物生长发育中,脂肪酸和三酰甘油具有重要功能。分析了植物种子油脂合成代谢过程调控研究进展,总结了改良植物种子油脂策略：①调节碳源分配,抑制碳源流入蛋白质合成路径的关键酶编码基因的表达、增强碳源流入脂肪酸合成路径的关键酶编码基因的表达;②干预油脂合成,促进脂肪酸生物合成,提高三酰甘油组装过程的关键酶编码基因的表达水平;③提高种子油脂的品质：改变植物脂肪酸组成,调节脂肪酸脱氢酶基因的表达,引入外源超长链多不饱和脂肪酸合成途径;④调控油脂合成代谢途径的转录因子表达,提高种子油脂含量。还讨论了植物油脂合成的三酰甘油前体转运机制及合成途径多基因共同调节合成途径等。     

Enzymatic modification of transfer RNA

The molecular events leading to the synthesis of mature tRNA are only now becoming amenable to experimental study. In bacterial and mammalian cells tRNA genes are transcribed into precursor tRNA. These molecules, when isolated, contain additional nucleotides at both ends (20) of the mature tRNA and lack most modified nucleosides. Presumably, specific nucleases ("trimming" enzymes) cut the precursor to proper tRNA size. The C-C-A nucleotide sequence of the amino acid acceptor end common to all tRNA's does not seem to be coded by tRNA genes (30), and may be added to the trimmed molecules by the tRNA-CMP-AMP-pyrophosphorylase (71). Modifications at the polynucleotide level of the heterocyclic bases or the sugar residues give rise to the modified nucleosides in tRNA. Although newly available substrates have allowed the detection of more of the enzymes involved in these reactions, there is still no knowledge about the sequence of modification or trimming events leading to the synthesis of active tRNA. Progress in these studies may not be easy because enzyme preparations free of nucleases or other tRNA modifying enzymes are required. The role of the modified nucleosides in the biological functions of tRNA is still unknown. Possibly pseudouridine is required for ribosome mediated protein synthesis; some other modified nucleosides in tRNA are not required for this reaction, but may enhance its rate. What might be the role of the large variety of modified nucleosides in tRNA? One is tempted to speculate that such nucleosides are important in other cellular processes in which tRNA is thought to participate such as virus infection, cell differentiation, and hormone action (2, 3). Mutants in a number of tRNA-modifying enzymes are needed in order to extend our knowledge of their purpose and of tRNA involvement in other biological processes. But unless tRNA-modifying enzymes specific for a particular tRNA species exist, no simple selection procedure can be devised. Possibly some of the regulatory mutants of amino acid biosynthesis may prove to affect tRNA-modifying enzymes (72). Transfer RNA's are macromolecules well suited for the study of nucleic acid-protein interactions. The tRNA molecules are structurally very similar, and they interact with a large number of enzymes or protein factors (2, 3). Each aminoacyl-tRNA synthetase, for instance, very precisely recognizes a set of cognate isoacceptor tRNA's (2, 73). The availability of the tRNA- modifying enzymes adds another dimension to the problem of the nature of specific recognition of tRNA by proteins. There are some tRNA-modifying enzymes, such as the uracil-tRNA methylase, which may recognize all tRNA species, while others, such as the isopentenyl-tRNA transferase, probably recognize only a selected set of tRNA molecules, even with different amino acid accepting capacities. With well-characterized RNA precursor and tRNA molecules we can hope to delineate those features of primary, secondary, and tertiary structure involved in the specific interactions of tRNA with these enzymes.     

鸡肝NADPH生成酶与腹脂关系的研究

利用育成的黄羽鸡新扬州鸡，研究了鸡肝内ＮＡＤＰＨ生成酶与腹脂、屠体性状的关系，结果表明，１７周龄３种ＮＡＤＰＨ生成酶中，苹果酸脱氢酶（ＭＤ）活性最高，６－磷酸葡萄糖脱氢酶（ＧＰ）次之，异柠檬酸脱氢酶（ＩＳ）最小。苹果酸脱氢酶可能是脂肪合成过程中提供氢的最主要的酶，３种酶与腹脂重、腹脂率均呈正相关，与屠体性状呈正或负的弱相关，说明３种ＮＡＤＰＨ生成酶活性低时，鸡的腹脂重（率）降低，产肉性能提高，表明此酶的活性有可能作为选择低脂以鸡的辅助手段