植物叶片在衰老期间膜结构变化研究进展

引起生物体的器官或某一部分最终走向死亡的变化即为衰老(senescence),所有高等植物在其生活史上的任何阶段,或在任何结构水平上,衰老均可发生。衰老作为植物生长发育中的重要事件,受到研究者们的极大关注。1908年minot首先对植物的衰老进行了研究,对植物器官衰老研究最多的是叶片和子叶,一般地,子叶的衰老与叶片的衰老没有本质的差异。     

植物Whirly蛋白调控叶片衰老的研究进展

植物衰老是植物细胞生长发育的最后一个阶段,其启动的早晚对植物生物量和品质的形成有很大影响。叶片衰老是植物衰老的主要形式,受到内外环境因素的诱导,并被多种转录因子介导的信号传导途径所调控。对叶片衰老调控机制的研究一直是植物衰老研究中的重点。Whirly蛋白作为一类广泛存于植物中的特异转录因子小家族,能与单链DNA分子结合,双定位于细胞器(线粒体或叶绿体)与细胞核中,在植物细胞核和细胞器中发挥多种功能,参与对植物叶片衰老的调控。本文概述了植物Whirly蛋白的结构和定位,重点阐述了Whirly蛋白的功能与细胞衰老关系及其对叶片衰老调节机理的研究进展等,并对未来的研究方向进行了展望。     

植物衰老期间生理生化变化的研究进展

植物衰老是受内外因素控制的细胞有序降解并最终导致死亡的过程,衰老期间会出现与正常生长阶段不同的生理生化变化。植物衰老引起的各种功能的下降极大地限制了作物产量潜力的发挥,种子贮存过程中的衰变、逆境条件下植株的早衰、果蔬采后贮藏衰老导致货架寿命的缩短等均会造成极大的经济损失。研究植物衰老的生理机制及其调控具有十分重要的意义。综述了有关植物衰老时生理生化变化方面的近期研究进展,以利于人们对植物衰老生理的更深入的了解。     

植物衰老中的编程性细胞死亡

本文通过对植物衰老和动植物中编程性细胞死亡(PCD)的研究,阐述了植物衰老中PCD存在的依据,澄清了植物衰老和PCD的关系,提出了植物衰老中可能的PCD发生途径,为调控植物衰老的遗传操作提供依据。     

植物衰老中的编程性细胞死亡

本文通过对植物衰老和动植物中编程性细胞死亡(PCD)的研究,阐述了植物衰老中PCD存在的依据,澄清了植物衰老和PCD的关系,提出了植物衰老中可能的PCD发生途径,为调控植物衰老的遗传操作提供依据.     

谈谈植物的衰老

植物的衰老是指一个器官或整个植株的生命功能衰退、最终导致自然死亡的一系列变化的过程。衰老和死亡是植物的必然终结,认识衰老的原因,设法推迟衰老的进程是可能的。例如,水稻、小麦、棉花和油菜等作物的生长后期,由于肥水条件不良,常出现不同程度的早衰现象,影响...     

不同制剂在月季切花保鲜中的效果研究

以月季为材料,通过各种微生物保鲜剂的保鲜,了解其保鲜效果,并观察衰老过程中微生物与植物材料自身的生理变化,以探讨衰老原因。     

表观遗传调控植物叶片衰老的研究进展

植物叶片衰老是一个非常重要的发育过程,涉及大分子的有序分解从而将营养物质从叶片转移到其他器官,对植物的生存和适应至关重要。叶片衰老主要受植物的发育调控,但同时也受内部和外部环境因素的影响,涉及高度复杂的基因调控网络和多层级的调控。近年来的研究表明表观遗传是调控植物叶片衰老的一种重要调控方式。该研究综述了植物叶片衰老过程中的表观遗传调控机制,包括组蛋白修饰、DNA甲基化、ATP依赖的染色质重塑和非编码RNA介导的调控,并对该领域今后的发展方向进行了展望。     

一氧化氮与植物成熟衰老的关系

植物体可以通过依赖于类似哺乳动物的一氧化氮合成酶或硝酸还原酶的酶促合成途径和非酶促合成途径产生一氧化氮。植物内源一氧化氮可以通过抑制乙烯的生物合成和调控环化核苷酸在植物组织中的水平,来延缓植物组织的成熟和衰老,延长果蔬等组织的货架期。     

4—PU和6—BA对萝卜离体子叶衰老的延缓和脂质过氧化的影响

自70年代在植物衰老研究中引入自由基假说后,国内外不少研究表明在叶片衰老过程中确有自由基的参与,并导致脂质过氧化。近年来,许多研究者在植物生长调节物质延缓或加速植物衰老作用机理的研究中也非常重视自由基的作用。Leopold和Kriedemann〔1〕指出激动素有“基于自身氧化的刹车作用”。Leshem等〔2〕和Dhindsa等〔3〕报告细胞分裂素在延缓植物衰老方面的作用与它能清除自由基、阻止自由基的形成有关。李伯林等〔4〕用燕麦叶片为材料,发现6BA和2,4D在植物体内可作为直接和间接的自由基清除剂而延缓植物的衰老。早在50年代中后期就有报…     

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.     

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     

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.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various     

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

<正>Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However, there is limited genome information of IBDV