脱春化对冬小麦幼芽中可溶性蛋白质组成及植株个体发育状态的影响

Tomita 曾证明冬小麦经长时间低温诱导之后有新的蛋白质形成;Dévay 观察到在低温下合成一种核糖核酸酶Ⅰ;Sasaki 证明,冬小麦幼苗的染色质中有一种耐低温的核糖核酸酶.但这些在低温下形成的蛋白质是否与发育过程有关,尚未得到证明。应用蛋白质合成的专一性抑制剂的实验表明,在低温诱导的中期,氯霉素能抑制春化过程的进行,而在这之前或之后都没有抑制作用。说明在春化过程中期,植株体内的蛋白质合成     

冬小麦幼苗春化期间过氧化物酶的变化

研究了冬小麦幼苗在春化过程中过氧化物酶同工酶谱、过氧化物酶活性和可溶性蛋白质含量的变化。在冬小麦春化过程的中期,过氧化物酶同工酶谱存在着较显著的变化,第二条主要谱带逐渐减弱和接近消失,靠近正极的第四条主要酶带有所加强。而舂小麦正相反,第四条及第五条酶带都因春化处理而减弱。同时观察到春化21天以后冬小麦幼苗可溶性蛋白质含量迅速增加。     

春化处理控制冬小麦的小穗发育

春化作用是决定冬性及二年草本植物成花和穗化的一个关键生理过程,通过用不同时间的前期低温处理,观察对冬小麦（Triticum aestivum L.)后期形态建成中穗分化启动,小花发育及结实率的影响,发现前期低温处理对穗启动分化的早晚具有决定作用,春化时间越长,穗分化启动越早,较长时间低温有利于促进穗分化,在实验室低温处理条件下,促进小花分化和提高结实率的最佳春化处理时间是45d左右,实验观察表明,春化处理促进小麦生长锥分化启动时间和分化速率,减少小穗退化,这一结果表明了春化处理不仅是冬小麦开花启动过程所必需的,而且是花序正常发育过程和顶部与基部小穗完全结实所不可缺少的。     

冬小麦春化过程中低温诱导的与花芽分化相关的mRNA和蛋白质的合成

应用SDS电泳及高分辨双向电泳技术,分析了冬小麦经春化、脱春化及超期春化处理后茎类蛋白质组分的变化。发现52.5,38kD和16.2kD蛋白质与冬小麦开花诱导密切相关。mRNA体外翻译结果表明,春化作用中低温诱导与开花紧密相关的mRNA的出现有一定的顺序性。因此推测:春化诱导开花是低温导致某些特定基因表达的结果,而表达的调节主要发生在转录水平上。     

冬小麦春化相关基因cDNA(verc203)片段序列的分析

春化作用是高等植物发育的重要环节之一,它是受遗传控制的生理过程,人们对此现象已作了生态、生理和生化方面的研究（谭克辉1983）。认为植物茎尖生长点接受低温诱导后,会引起体内许多代谢途径和方式的顺序改变（种康和谭克辉1993）,可能导致春化相关基因启动表达。有人（Burn等1993）提出春化相关基因启动表达可能是基因脱甲基化结果的观点。但这一假说尚缺乏直接的强有力证据。违斌和谭克辉（199）系统地研究了冬小麦春化过程中核酸、蛋白质代谢与春化作用的直接相关关系和春化特异蛋白质代谢与特异性rnRNA出现的重要意义,确信春化…     

植物同源结构域指蛋白在拟南芥等十字花科植物春化作用途径中的功能

春化低温处理可以使拟南芥等十字花科植物提前开花,该过程中涉及到一个重要的植物同源结构域指(PHD-finger)蛋白VERNALIZATION INSENSITIVE3(VIN3)。PHD-finger结构域是真核生物中一种进化保守的锌指结构域,通常参与蛋白质之间的相互作用,特别是对核小体组蛋白进行甲基化、乙酰化、磷酸化等修饰。在春化处理过程中,VIN3及其同源基因编码的蛋白都具有PHD-finger结构域,该结构域通过对开花抑制基因FLOWERING LOCUS C染色质组蛋白进行H3K9、H3K27甲基化、H3K9和H3K14去乙酰化等修饰,调节FLC染色质结构状态,使其从松弛状态转变为高度凝缩状态而关闭其功能,从而影响FLC转录活性进而促进开花。以下综述了拟南芥等十字花科植物春化作用途径中PHD-finger蛋白的功能,并且概述了春化作用机制。     

植物如何消除春化的记忆——ELF6阻止春化状态遗传给下一代

<正>植物能够感知周围环境,控制和协调自身的发育,使其在合适的时间开花结果。春化过程就是一个很好的例子,植物通过感受冬天连续的低温环境,逐渐抑制开花抑制因子的表达,并且能够在冬季之后保持该基因的抑制状态,即植物通过表观修饰可以在随后的发育过程中记住基因的表达状态,从而促进开花。春化对于许多冬性作物(如小麦、大麦)的高产、稳产也具有重要作用。模式植物拟南芥和作物通过不同的开花抑制因子(例如:拟南芥中FLC和小麦及大麦中VRN2)响应春化过程,但研究认为它们具有类似的调节机制。认识拟南芥中FLC的调节对     

玉米赤霉烯酮在冬小麦短日春化中的作用

应用酶联免疫技术,研究了冬小麦品种燕大１８１７ 在不同光周期条件下,体内内源玉米赤霉烯酮（ＺＥＮ） 和ＡＢＡ 含量的变化。结果表明,冬小麦品种燕大１８１７ 具有短日春化性,苗期经４ 周ＳＤ 处理后转到ＬＤ 下能正常抽穗。ＳＤ 诱导春化的幼苗茎尖和叶片中ＺＥＮ 含量高于未经诱导的ＬＤ 幼苗,而在两种光周期条件下生长的幼苗中ＡＢＡ 含量变化趋势并无明显差异。马拉硫磷（ ＭＡＬ） 抑制ＳＤ 幼苗体内ＺＥＮ 含量高峰的出现,也部分抑制抽穗;外源ＺＥＮ 可部分抵消ＭＡＬ对植株的影响,降低茎尖内源ＡＢＡ 含量,并有促进小麦拔节的作用。说明在冬小麦短日春化过程中,ＺＥＮ 具有促进作用,而ＡＢＡ 没有直接影响。     

冬小麦春化作用相关cDNA克隆Vrc79的分子克隆

在低温需求型植物的发育过程中,春化作用是诱导植物成花的必要因子。在冬小麦春化进程中存在着一个核酸代谢的关键期,为了探讨春化作用的分子机理,以不春化及脱春化的冬小麦京冬1号（Ｔｒｉｔｉｃｕｍ　ａｅｓｔｉｖｕｍＬ．ｃｖ．Ｊｉｎｄｏｎｇ　Ｎｏ．１）胚芽的ｍＲＮＡ为对照,通过减法杂交构建了富集冬小麦春化相关基因的ｃＤＮＡ文库,经过差异筛选分离到了一个仅在春化２１ｄ这一关键期表达,而在不春化、春化４ｄ、脱春化不表达的春化相关。ｃＤＮＡ克隆Ｖｒｃ７９。Ｎｏｒｔｈｅｍ杂交及同源性分析表明它是一个在植物中新发现的不同于低温胁迫诱导基因的春化特异克隆,其对春化需求型植物的成花诱导可能起重要的调控作用。     

冬小麦品种DS1号生育进程的温光效应

DS1号是适于 2 2 .5 kg/hm2 播种量的秋播冬小麦品种。为了掌握其温光反应特性 ,为确定它的适宜种植范围提供试验依据 ,2 0 0 1年和 2 0 0 2年 ,用这个小麦品种在人工气候箱内进行了 8种不同温光组合的生态模拟试验。参试品种是 DS1号。每台气候箱的体积为 5 0× 5 0× 1 0 0 cm3。试验过程中 ,箱内相对湿度是70 %～ 78%。光照强度为 90 0 0 lx。试验结果显示 ,在不同处理中 ,出苗至抽穗过程中 ,≥ 5℃积温和天数差异极大。结果表明 ,低温不是唯一的春化条件。在 8种不同的处理中 ,植株抽穗前 ,表现了不同的温光效应。在生育前期 5℃的处理中 ,可以完成春化 ,与之配合的 1 6h光照的长日条件或 8h光照的短日条件均可。在2 0℃和 8h光照的处理中 ,未表现出短日春化效应 ,或抽穗期显著拖长。短日春化可能要有一定的光照强度相配合。生育前期或直至抽穗前 ,在 2 0℃和 1 6h长日条件下 ,可以通过“非春化途径”完成抽穗前的生育进程 ,出苗～生理拔节和出苗～抽穗阶段并不拖长或略长     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

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.

     

Novel compounds with potent CDK9 inhibitory activity for the treatment of myeloma

Cyclin-dependent kinases (CDKs) and Polo-like kinases (PLKs) play key role in the regulation of the cell cycle. The aim of our study was originally the further development of our recently discovered polo-like kinase 1 (PLK1) inhibitors. A series of new 2,4-disubstituted pyrimidine derivatives were synthesized around the original hit, but their PLK1 inhibitory activity was very poor. However the novel compounds showed nanomolar CDK9 inhibitory activity and very good antiproliferative effect on multiple myeloma cell lines (RPMI-8226).