植物细胞中的蛋白体

植物细胞有多种类型的质体,其中的蛋白质体由前质体发育而来,在植物个体发育中形成较早.蛋白质体中常含有大小不等的蛋白颗粒,这种颗粒电子致密度较高,与细胞内其他结构相比有显著差异.较大的蛋白颗粒其体积几乎占据整个质体空间,称之为蛋白体(Pro-tein bodies,简称PB).1967年Newcomob 等首先在蚕豆根尖细胞中发现,质体中存在着     

固定化植物细胞

植物除了为人类提供生命必需的碳水化合物,脂类以及蛋白质外,还为我们提供许多有益的次生代谢物如生物碱、萜类、甾体、酚类以及醌类物质.据统计在三万种已知的天然产物中大约有80%是来自植物界,但是长期以来这些物质的供应仅能依靠整株植物的栽培或野生植物的采集来实现.由于植物的生长和栽培受到气候、地理、季节以及政府禁令等的影响,使得这些物质的供应既不充分又不稳定,因此在植物细胞培养成功不久,人们就     

植物细胞的程序化死亡

细胞程序化死亡(programmed cell death,PCD)是多细胞生物体中一些细胞所采取的一种由自身基因调控的主动的死亡方式。与细胞增殖一样,作为细胞生命活动的一个重要组成部分,PCD的研究越来越受到生物学家的重视。 1972年,Kerr、Wyllie和Currie将他们观察到的一种与细胞坏死(Necrosis)形态特征截然不同的细胞死亡的现象,称之为细胞凋亡     

植物细胞的肌醇磷脂信息传递系统

本文就（1）肌醇磷脂信息传递系统在植物中的存在,（2）肌醇磷脂的代谢途径、特点,（3）肌醇磷脂信息传递系统在外界刺激与生理生化反应之间的联系作用三个方面的研究进展进行介绍,并讨论这一领域研究中存在的问题和遇到的困难。     

植物细胞的水孔蛋白

对近年来发现和研究的转运水分跨膜运输的蛋白—水孔蛋白（aquaporins）,从种类、结构、功能调控及生理意义方面作了介绍。     

微重力植物细胞生理学研究进展

本文介绍1985年以来微重力植物细胞生理学飞行试验和地面模拟研究进展。     

园艺植物细胞的超微结构研究

细胞是生物体最基本的结构和功能单位。综述了园艺植物的器官生长发育过程中细胞的超微结构研究,果实发育过程中的组织及细胞超微结构研究,逆境下不同器官细胞超微结构变化的研究。指出了当前研究中的不足及今后的发展方向。     

PEMT2过表达增强大鼠肝癌细胞cAMP的表达

目的：在大鼠肝癌细胞株CBRH-7919中研究磷脂酰乙醇胺-N-甲基转移酶2（PEMT2）过表达对cAMP表达量的影响。方法：利用基因转染技术建立PEMT2过表达的大鼠肝癌细胞株,用免疫细胞化学法观察cAMP的表达情况,用[^3H]-cAMP掺入法测定cAMP的含量,用流式细胞术分析细胞周期的变化,并与原代培养大鼠肝细胞比较。结果：cAMP在原代培养的肝细胞中表达较高,在肝癌细胞中含量均较低,PEMT2高表达可明显提高肝癌细胞内cAMP的含量。结论：PEMT2表达抑制肝癌细胞的生长可能与cAMP介导的信号转导通路加强有关。     

pH: Signal and Messenger in Plant Cells

Abstract: Since water spontaneously ionizes, protons cannot be removed from the medium: their free concentration in cells must be regulated through actively controlling H⁺‐related transport across membranes, by active and passive buffering, and by setting a certain pH within the metabolic network. Whereas these are the basic tools that provide effective H⁺ homeostasis, cellular compartmentation serves as an intermediate store into which protons can be shifted temporarily and from which protons can be regained when required. On the other hand, intracellular compartments can also serve as a final proton sink. pH regulation is not confined to intracellular spaces, but also comprises the apoplast. Whereas the pH of the cytosol is kept slightly alkaline at 7.2 to 7.5, with an average buffer capacity of 20 to 80 mM H⁺ per pH unit, the apoplastic pH may vary among tissues but is always acidic, with values between pH 5 and 6 and with a buffer capacity in the lower millimolar range per pH unit. pH can be a signal and/or a messenger, a distinction not always clearly made. Here, “signal” should be understood as information about an ongoing or preceding process, whereas “messenger” would be the carrying of certain information that will lead to a change of state. As such, pH would signal light intensity changes, drought, lack of oxygen and the presence of symbiotic partners or microbial attackers. On the other hand, pH would be a messenger in situations where pH changes are preconditions for certain processes, e.g., the gravity response or for activation of certain transporters in stomatal movements, and possibly for growth. The function of pH as a cellular messenger raises the question of whether pH should be understood as a “second messenger” in the way this is done for Ca²⁺. In an effort to give a comprehensive answer to this problem, the different roles of Ca²⁺ and H⁺ in cellular signalling are discussed and a number of Ca²⁺/pH interactions are presented.     

cAMP 参与烟草悬浮细胞的ABA信号转导

ABA诱导型启动子(rd29A)重组到报告基因(GUS)的上游构建表达载体.通过农杆菌介导转化烟草,获得转基因植株.将转基因植株诱导愈伤组织,建立稳定、均一的转rd29A-GUS融合基因的悬浮培养细胞系.用ABA处理悬浮细胞24 h后GUS活性显著升高,说明外源ABA能够诱导rd29A启动子的表达,获得了用于ABA信号转导研究的实用细胞系.在ABA激活表达的细胞介质中加入尼克酰胺(cADPR合成酶的抑制剂)或U73122(PLC抑制剂)只能部分抑制ABA的效应,但如果加入蛋白激酶抑制剂K252a,抑制效果达95%以上.用可跨膜的cAMP的类似物8-Br-cAMP处理细胞发现,它能代替ABA的作用;当介质中加入1 mmol/L IBMX(磷酸二酯酶的抑制剂)增加cAMP的稳定性,发现低浓度的8-Br-cAMP与ABA相同的效应.以上结果表明cAMP参与了烟草悬浮细胞中ABA信号的传递.     

改变大鼠促性腺激素细胞内cAMP含量对卵泡刺激素分泌的影响

目的:分析大鼠卵泡刺激素(FSH)分泌的受体后信号转导机制。方法:将促性腺激素(GTH)细胞用毛喉素(FSK)或腺苷酸环化酶抑制剂SQ22536处理后,用促性腺激素释放激素脉冲刺激,再用酶联免疫吸附法检测其FSH分泌量,并与空白对照组比较。结果:FSK能显著提高GTH细胞中环磷酸腺苷(cAMP)含量,SQ22536能显著降低GTH细胞中的cAMP含量,FSK和SQ22536都不会影响GTH细胞的蛋白激酶C活性,GTH细胞cAMP含量的变化对FSH分泌的影响不显著。结论:cAMP-PKA(蛋白激酶A)不是FSHβ亚基分泌的受体后信号转导途径。     

The Effect of cAMP on Phosphohydrolase Activity of the Barley Root Cells

We studied the effects of cAMP on phosphohydrolase activity in the microsomal fraction and its 0.5 M KCl extract. In both preparations, cAMP inhibited the activity of acid phosphatases. In the microsomal fraction, a 50% inhibition of acid cation-dependent (Mg²⁺, Cu²⁺) phosphatase was induced at pH 6.0 by 10 M cAMP; whereas, for cation-independent phosphatase, this effect was exerted only by 50 M cAMP. In the KCl extract, the sensitivity of both cation-dependent and cation-independent acid phosphatases to cAMP was higher than in the microsomal fraction. Cyclic AMP did not reduce the activity of nucleosidases. Selectivity in the cAMP action on acid phosphatases is assumed to be one of the mechanisms controlling the biochemical activity outside the barley root cells.     

表油菜素内酯对cAMP在植物体内分在和对质膜ATPase活性的影响

植物材料经ｅｐｉＢＲ处理后,ｃＡＭＰ的水平明显提高,比对照增加１～３倍,其变化的时间进程有６ｈ的滞后期。小麦根系质膜ＡＴＰａｓｅ与ｅｎｉＢＲ一起温育,质膜ＡＴＰａｓｅ活性未表现提高,反而明显下降;当ｅｐｉＢＲ浓度提高到２×１０－６ｍｏｌ／Ｌ时,质膜ＡＴＰａｓｅ活性降低过半。在此反应系统中加入５×１０－５ｍｏｌ／Ｌ的ＩＡＡ后,质膜ＡＴＰａｓｅ活性明显提高,并超过了单独使用ＩＡＡ处理的材料。放射自显影表明,油菜素甾酮主要分布在绿豆幼苗上胚轴近真对端１ｃｍ处及黄瓜幼苗生长锥和子叶基部,均为形态生长旺盛的部位。     

双歧杆菌培养滤液中核酸的提取及对肠癌细胞cAMP,cGMP的影响

实验观察了对数期长双歧杆菌、青春双歧杆菌培养滤液中提取的总核酸对肠癌细胞ｃＡＭＰ、ｃＧＭＰ的影响。结果发现,双歧杆菌培养中滤液中存在大量核酸,将双歧杆菌培养滤中的核提取纯化作用于大肠癌细胞ＣＣＬ１８７,ｃＡＭＰ增高,ＣＧＭＰ没有变化,提示核酸可能作为细胞膜外的第一信使物质腺苷环化酶活性。     

cGMP、cAMP及两种cAMP衍生物对大鼠肝细胞核体外转录系统的影响

 本文介绍了以α-鹅膏蕈碱和低浓度KCl为手段建立了RNA聚合酶Ⅰ、RNA聚合酶Ⅱ活性的细胞核转录系统进而研究了cGMP、cAMP、cAMP丁酯及cAMP硫代环磷酰二乙胺对大鼠肝细胞核中RNA聚合酶Ⅰ与Ⅱ活性的影响。结果显示cGMP可以提高RNA聚合酶Ⅰ的活性;cAMP主要提高RNA聚合酶Ⅱ的活极,而cAMP分子结构变化产生的丁酯及硫代环磷酰二乙胺衍生物可增强cAMP的这种作用,为深入研究cAMP的构效关系提供了实验依据。     

Translation of Vesicular Stomatitis Messenger RNA by Extracts from Mammalian and Plant Cells

RNA was isolated from polyribosomes of vesicular stomatitis virus (VSV)-infected cells and tested for its ability to direct protein synthesis in extracts of animal and plant cells. In cell-free, non-preincubated extracts of rabbit reticulocytes, the 28S VSV RNA stimulated synthesis of a protein the size of the vesicular stomatitis virus L protein whereas the 13 to 15S RNA directed synthesis of the VSV M, N, NS, and possibly G proteins. In wheat germ extracts, 13 to 15S RNA also directed synthesis of the N, NS, M, and possibly G proteins. Analysis of extracts labeled with formyl [(35)S]methionine showed that the 28S RNA directed the initiation of synthesis of one protein, whereas the 13 to 15S RNA directed initiation of at least four proteins. It is concluded that the 28S RNA encodes only the L protein, whereas the 13 to 15S RNA is a mixture of species, presumably monocistronic, which code for the four other known vesicular stomatitis virus proteins.