植物细胞凋亡的研究进展

大量的实验研究表明细胞凋亡普遍存在于植物中 ,对于植物的正常生长发育及病理过程具有十分重要的生物学意义。植物细胞与动物细胞凋亡有许多相似的特征 ;在凋亡过程中有核酸内切酶的激活以及类caspase的参与 ;尽管植物细胞与动物细胞凋亡具有相似特征和机制 。

植物细胞凋亡研究进展

植物细胞凋亡是植物发育或与环境的相互作用过程中植物体的一些已完成使命或不需要的细胞被选择性消除的过程。介绍了植物细胞凋亡的特点、种类以及研究方法,并与动物细胞凋亡进行了对比分析。

植物细胞凋亡的ELISA检测

本文利用TUNEL方法在单个细胞水平上对苯胺灵诱导的玉米根尖细胞死亡进行了检测。结果表明，一定浓度的苯胺灵能诱导玉米根尖细胞发生主动性的细胞凋亡，具有细胞凋亡典型的形态和生化特征即细胞核浓缩并形成核碎片、染色质边缘化及DNA特异片段化等（Fig.1)。首次利用ELISA方法在群体水平上对这种细胞凋亡进行了进一步检测。结果表明：动物细胞研究常用的ELISA方法同样也适合用于植物细胞凋亡的检测。在凋亡前期，随着凋亡过程的进行，细胞质中的OD值逐渐上升（Fig.2)。剂量实验表明，0．2mg/mL苯胺灵最适合于诱导细胞凋亡（Fig.3)。

Programmed Cell Death in Plants--- A New Emerging Research Field

There is increasing evidence shows that programmed cell death (PCD) can occur underphysiological, pathological or stress conditions in plants. The present review describes themorphological and biochemical characteristics, physiological functions, and the research significance ofplant PCD in detail as well as makes comparison betWeen these aspects with those in animals. Inaddition, this paper is also making exploration of the possible pathway for signal transduction, geneticregulation of plant PCD, origin and evolution of PCD and proposes a tactic for research on plant PCDalthough it is still in a preliminary stage.Compared to PCD in animals, PCD in plants under various conditions has revealed much greaterdifference in morphological and biochemical characteristics, which presents different essence far fromthe definition of apoptosis of animals. Nevertheless, no inflammation, specific fragmentation of DNAand rise of the activities of endonuclease and protease in plant PCD are still typical hallmarks fordistinguishing PCD from necrosis. On view of molecular level, as in animals, PCD in plants is alsoregulated by specific genes and involves signal transduction pathway with the involvement of a varietyof signal molecules.The physiological functions of plant PCD are similar to those in animals too. In the importantphysiological and pathological processes in plants, i.e., during reproduction, development, growth,senescenced disease-resistance, and stress-resistance against adverse circumstance conditions, PCDtakes on functions as important as proliferation throughout the whole life cycle of living organisms.Obviously, the research on PCD in plants is of vital importance that should not be ignored either intheory or in agricultural production.At present, the research on PCD in plants is focusing on collecting morphological and biochemicalevidences. But many molecules of initiation signal participating in plant PCD have been identified andseveral genes directly related to this process were isolated, which provide useful enlightenment forillustrating signal transduction pathway of PCD. Moreover, some conserved signal molecules andregulating genes were found in plant PCD, and caspase-like proteases have been detected in HR celldeath as well as in development-associated PCD. These data provide strong evidence at molecular levelfor conservation and the origin and evolution of PCD.1 The authors want to extend the sincerely thanks to Prof. Michele C. Heath (University of Toronto, Canada),Prof. Niroo Fukuda (University of Tokyo, Japan), Prof. Duran L. Nooden (University of Michigan, USA),Prof. Chris Lamb (Salk institute, California), Prof. Sarah Hake (Agricultural Research Service, USA), Prof.David L. Vaux (The Walter and Eliza Hall insititue of Medical Research, Post Office Royal MelbourneHospital, Australia), Associate Prof. Jeffrey L. Dangl (University of North Carolina, USA), Associate Prof.Eric Lain (The State University of New Jersey, USA), Dr. Maki Katsuhara (Okayama University, Japan),Prof. Sarah Hake (AgricultUral Research Service, USA), Dr. Peter P. Repetti (University of California,USA), Da Blazena Koukalova (Academy of Sciences of the Czech Republic, CZ), Dr. Iona Weir(Horticulture and Food Research Institute of New Zealand, New Zealand), Dr. Thorsten Jabs (Institute forBiology III, Germany), Dr. Hong Wang (University of California, USA) and Dr. Patrick Gallois (Universityof Perpignan, France) for their kind providing their personal latest data of their research concerned andoffering academic exchanges with us.This project is granted by the National Natural Science Foundation of China (No. 39870423) and by StateCommission of Education, Doctorate Spot Foundation.Author for correspondence. E-mail: ycsong@whu.edu.cn.Evidences in various aspects indicate that PCD origins from prokaryote, and various forms of PCD arefound along the phylogenic tree.Conclusion: A variety of endogenous and exogenous signals can break the homeostasis within plantbody and result in differentiation, proliferation, quiescence, or death of cell at length

Induction of apoptosis in purified animal and plant nuclei by Xenopus egg extracts

We have developed a cell-free system that can trigger the nuclei purified from mouse liver and suspensioncultured carrot cells to undergo apoptosis as defined by the formation of apoptotic bodies and nucleosomal DNA fragments. The effects of different divalent cations and cycloheximide on DNA cleavage in this system were assessed.The fact that nuclei of plant cells can be induced to undergo apoptosis in a cell-free animal system suggests that animals and plants share a common signal transduction pathway triggering in the initiation stage of apoptosis.

Effects of Pinus massoniana bark extract on cell proliferation and apoptosis of human hepatoma BEL-7402 cells

AIM: To study the effects of Pinus massoniana bark extract (PMBE) on cell proliferation and apoptosis of human hepatoma BEL-7402 cells and to elucidate its molecular mechanism.METHODS: BEL-7402 cells were incubated with various concentrations (20-200 μg/mL) of PMBE for different periods of time. After 48 h, cell proliferation was determined by 3-(4,5-dimethyl-thiazolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) assay. Apoptosis was evaluated by morphological observation, agarose gel electrophoresis,and flow cytometry analysis. Possible molecular mechanisms were primarily explored through immunohistochemical staining.RESULTS: PMBE (20-200 μg/mL) significantly suppressed BEL-7402 cell proliferation in a time- and dose-dependent manner. After treatment of BEL-7402 cells with 160 μg/mL PMBE for 24, 48, or 72 h, a typical apoptotic 'DNA ladder'was observed using agarose gel electrophoresis. Nuclear condensation and boundary aggregation or split, apoptotic bodies were seen by fluorescence and electron microscopy.Sub-G1 curves were displayed by flow cytometry analysis.PMBE decreased the expression levels of Bcl-2 protein in a time-dependent manner after treatment of cells with 160 μg/mL PMBE.CONCLUSION: PMBE suppresses proliferation of BEL-7402 cells in a time- and dose-dependent manner and induces cell apoptosis by possibly downregulating the expression of the bcl-2 gene.

Antitumor Activities of Apple Extracts

OBJECTIVE To examine the antitumor activities of fresh apple extracts. METHODS Fuji apple extracts were tested for their anti-LS^174T-pro-liferative activities, for their effect on expression of PCNA, and ability to induce apoptosis in a LS-174T cell line. RESULTS Apple extracts inhibited LS-174T cellular proliferation in a concentration and time dependent manner. The apple extracts equivalent to a concentration of 50 mg/ml inhibited the proliferation of the LS-174T cells by 34.5±1.2% after 48 h and 47.5±1.8% after 72 h respectively. Apple extracts inhibited PCNA expression and induced apoptosis of the LS-174T cells at concentrations above 12.5mg/ml. CONCLUSION Apple extracts can inhibit PCNA expression and induction of apoptosis in LS-174T cells which may contribute to their inhibitio-ry effect on cellular proliferation.

Performance of Antoregldatory Senescence-inhibition Gene in Rice

The performance of wxtaraguiatory senescence-inhibition gene PSAG12-IPT in nee has been investigated in the study.422 tranagenic plants from 134 independent resistant calli were obtained from 4 rice varieties through Agrobacterium-mediated transformation.Among them,233 were positive PSAGIZ^IPT tranagenic plants identified by GUS histochemical assay and PCR analysis.Southern analysis showed the transgene was randomly integrated into rice genome,of which 42.29% was single copy.Investigations on photosynthesis function and agronomic characters of Rt generation showed that chlorophy Ⅱ content and photosynthesis rate of flag leaves in tranagenic plants,were 41.23% and 60.24% higher than the control wild-type rice,respectively.The growth duration and plant height of the tranagenic plants were similar to the control.Variations of other characters were dependent on the varieties.For the variety Millin with significant aging phenomenon in China,its total grains per hill,its seed setting rate and 1000-grain weight were increased by 40.44%,8.05% and 8.32% respectively.The results indicated that after leaf senescence of varieties liable to age was delayed,the seed setting rate and the filling degree of seeds were improved,which finally resulted in significantly increased seed yield and taomaas per hill.The new variety Wuyujing 2 without serious aging problem,was also increased in the panicles per hill,the total grains per hill,the seed yield per hill and biomass in different degrees.

植物NRP蛋白在逆境胁迫中的作用

植物体由于本身的固着式生长,当其面临外界的各种环境胁迫时,不断地进化出完善的应对机制来保持自身正常的生长发育.随着对植物抗逆胁迫响应机制的深入研究,许多响应机制被发现,尤其最近一个在植物中高度保守的新的信号分子NRP(N-rich protein)的发现,为植物逆境胁迫响应机制的进一步研究提供了分子基础,从而有助于作物的改良和增产.本文主要对NRP蛋白的发现过程和序列结构分析、参与植物逆境响应相关的信号转导途径以及已知的分子机制研究等方面做一简要的综述.