细胞因子在免疫反应和病毒相互作用中的机能

本文介绍了细胞因子信号传导及其产生的调节作用，着重介绍了干扰素以及几个炎性细胞因子的特性、信号传导途径及生物学功能，论述了病毒逃避宿主防御的机制以及细胞因子在免疫反应和病毒相互作用中的机能     

植物防御信号分子β-罗勒烯的研究进展

植物为了适应复杂的生活环境,在长期的进化过程中,发展起来了一套与动物免疫系统相似的、高度复杂的防御系统。研究表明,众多的信号分子在调控植物防御反应中起着重要作用。β-罗勒烯是一种与植物防御启动密切相关的信号分子。本文综述了信号分子罗勒烯的结构组成、自然分布、化学合成、植物防御以及信号途径等方面的研究进展,为其进一步的理论研究及农业应用提供了有益参考。     

外源茉莉酸和茉莉酸甲酯诱导植物抗虫作用及其机理

综述了茉莉酸(jasmonic acid, JA)和茉莉酸甲酯(methyl jasmo nate, MJA)的分子结构和应用其诱导的植物抗虫作用及其机制。植物受外源茉莉酸或茉莉酸甲酯刺激后,一条反应途径是由硬脂酸途径激活防御基因,另一条途径是直接激活防御基因。防御基因激活后导致代谢途径重新配置,并可能诱导植物产生下列4种效应：（1）直接防御,即植物产生对害虫有毒的物质、抗营养和抗消化的酶类,或具驱避性和妨碍行为作用的化合物;（2）间接防御,即产生吸引天敌的挥发物;（3）不防御,即无防御反应;（4）负防御,即产生吸引害虫的挥发物。     

虫害诱导的植物挥发物代谢调控机制研究进展

长期受自然界的非生物/生物侵害,植物逐步形成了复杂的防御机制,为防御植食性昆虫的为害,植物释放虫害诱导产生的挥发性化合物(herbivore-induced plant volatiles,HIPVs)。HIPVs是植物-植食性昆虫-天敌三级营养关系之间协同进化的结果。HIPVs的化学组分因植物、植食性昆虫种类的不同而有差异。生态系统中,HIPVs可在植物与节肢动物、植物与微生物、虫害植物与邻近的健康植物、或同一植株的受害和未受害部位间起作用,介导防御性反应。HIPVs作为寄主定位信号,在吸引捕食性、寄生性天敌过程中起着重要作用。HIPVs还可以作为植物间信息交流的工具,启动植株的防御反应而增强抗虫性。不论从生态学还是经济学角度来看,HIPVs对于农林生态系中害虫综合治理策略的完善具有重要意义。前期的研究在虫害诱导植物防御的化学生态学方面奠定了良好基础,目前更多的研究转向阐述虫害诱导植物抗性的分子机制。为了深入了解HIPVs的代谢调控机制,主要从以下几个方面进行了综述。因为植食性昆虫取食造成的植物损伤是与昆虫口腔分泌物共同作用的结果,所以首先阐述口腔分泌物在防御反应中的作用。挥发物诱导素volicitin和β-葡萄糖苷酶作为口腔分泌物的组分,是产生HIPVs的激发子,通过调节伤信号诱发HIPVs的释放。接着阐述了信号转导途径对HIPVs释放的调节作用,并讨论了不同信号途径之间的交互作用。就HIPVs的代谢过程而言,其过程受信号转导途径(包括茉莉酸、水杨酸、乙烯、过氧化氢信号途径)的调控,其中茉莉酸信号途径是诱发HIPVs释放的重要途径。基于前人的研究,综述了HIPVs的主要代谢过程及其过程中关键酶类的调控作用。文中的HIPVs主要包括萜烯类化合物、绿叶挥发物和莽草酸途径产生的芳香族化合物,如水杨酸甲酯和吲哚等。作为化学信号分子,这些化合物中的一部分还能激活邻近植物防御基因的表达。萜烯合酶是各种萜烯类化合物合成的关键酶类,脂氧合酶、过氧化氢裂解酶也是绿叶挥发物代谢途径中的研究热点,而苯丙氨酸裂解酶和水杨酸羧基甲基转移酶分别是合成水杨酸及其衍生物水杨酸甲酯的关键酶类。这些酶类的基因在转录水平上调控着HIPVs代谢途径。最后展望了HIPVs的研究前景。     

昆虫取食诱导的植物防御反应

植物被昆虫取食后可产生直接防御或间接防御。直接防御通过增加有毒的次生代谢产物或防御蛋白对昆虫生理代谢产生不利的影响,但对植物的消耗较大。间接防御通过释放挥发性化合物吸引天敌昆虫,并以此控制植食性昆虫。特异性的昆虫激发子(insect specific elicitors)能够诱导挥发性化合物的释放。多种信号途径参与昆虫取食诱导的植物防御反应,它们之间的相互作用协同或拮抗。了解昆虫取食诱导的植物防御反应,对于害虫综合治理策略的完善具有重要的意义。     

神经生长因子作用机理研究进展

神经生长因子在临床上具有重大的应用价值,它能通过多种信号传递途径起作用,对其机理的研究具有重要的理论意义。本就ＮＧＦ作用的早期效应阶段所涉及的激素作用途径进行综述,并讨论其中尚解决或存在争议的几个重要问题。     

植物间挥发物信号的研究进展

植物VOCs信号是植物间进行信息交流的"语言",可由多种生物和非生物因素诱导产生。非寄生植物释放的VOCs信号可影响其所在群落中其它植物的种子萌发与幼苗生长;而寄主植物释放的VOCs信号却是诱导寄生植物种子萌发和幼苗生长的信号物质。VOCs作为植物间的伤害信息可以诱导临近的同种或异种植物做好防御准备,从而通过主动或间接防御以减少外界的伤害。植物间通过VOCs信号进行信息交流,从而实现其繁衍与防御。该文通过对VOCs信号的种类、诱导产生因素、传递及作用进行综述,以期对VOCs信号的研究有所帮助。     

植物间挥发物信号的研究进展

植物VOCs信号是植物间进行信息交流的“语言”, 可由多种生物和非生物因素诱导产生。非寄生植物释放的VOCs信号可影响其所在群落中其它植物的种子萌发与幼苗生长; 而寄主植物释放的VOCs信号却是诱导寄生植物种子萌发和幼苗生长的信号物质。VOCs作为植物间的伤害信息可以诱导临近的同种或异种植物做好防御准备, 从而通过主动或间接防御以减少外界的伤害。植物间通过VOCs信号进行信息交流, 从而实现其繁衍与防御。该文通过对VOCs信号的种类、诱导产生因素、传递及作用进行综述, 以期对VOCs信号的研究有所帮助。     

ROS信号对植物抗性的调控作用研究进展

活性氧(reactive oxygen species,ROS)是植物体代谢所产生的小分子化合物,既是生长发育和防御途径的关键调节因子,又是需氧代谢的有毒副产物。植物细胞的生理过程受一个被活性氧调节的氧化还原网状途径的调控,本文从植物体内ROS产生的部位与时空特异性、ROS信号与NO和Ca2+波信号的互作等方面综述了ROS信号对植物抗性的调控作用研究进展。     

调控小鼠软骨细胞增生的分子机制

软骨细胞的增生受到多种信号的调控,阐述了调控软骨细胞增生的几个信号途径,包括TGF-β1、IHH/PTHrP、FGFs等几个信号途径。     

Study on the extraction, purification and quantification of jasmonic acid, abscisic acid and indole-3-acetic acid in plants

Introduction  – Jasmonic acid (JA), abscisic acid (ABA) and indole‐3‐acetic acid (IAA) are important plant hormones. Plant hormones are difficult to analyse because they occur in small concentrations and other substances in the plant interfere with their detection. Objective  – To develop a new, inexpensive procedure for the rapid extraction and purification of IAA, ABA and JA from various plant species. Methodology  – Samples were prepared by extraction of plant tissues with methanol and ethyl acetate. Then the extracts were further purified and enriched with C₁₈ cartridges. The final extracts were derivatised with diazomethane and then measured by GC‐MS. The results of the new methodology were compared with those of the Creelman and Mullet procedure. Results  – Sequential elution of the assimilates from the C₁₈ cartridges revealed that IAA and ABA eluted in 40% methanol, while JA subsequently eluted in 60% methanol. The new plant hormone extraction and purification procedure produced results that were comparable to those obtained with the Creelman and Mullet's procedure. This new procedure requires only 0.5 g leaf samples to quantify these compounds with high reliability and can simultaneously determine the concentrations of the three plant hormones. Conclusion  – A simple, inexpensive method was developed for determining endogenous IAA, ABA and JA concentrations in plant tissue. Copyright © 2008 John Wiley & Sons, Ltd.     

Biosynthesis of the polysialic acid capsule inEscherichia coli K1

The extracellular polysaccharides elaborated by most or all bacterial species function in cell-to-cell and cell-substratum adhesion, cell signaling, and avoidance or inhibition of noxious agents in animal hosts or free-living environments. Recent advances in our understanding of exopolysaccharide synthesis have been facilitated by comparative approaches in both plant and animal pathogens, as well as in microorganisms of industrial importance. One of the best understood of these systems is thekps locus for polysialic acid synthesis inEscherichia coli K1. The genes for sialic acid synthesis, activation, polymerization and translocation have been identified and assigned at least tentative functions in the synthetic and export pathways. Initial studies ofkps thermoregulation suggest that genetic control mechanisms will be involved which are distinct from those already described for several other exopolysaccharides. Information about the common as well as unique features of polysialic acid biosynthesis will increase our knowledge of microbial cell surfaces which in turn may suggest novel targets for therapeutic or industrial interventions.     

New insights into the regulation of plant immunity by amino acid metabolic pathways

Besides defence pathways regulated by classical stress hormones, distinct amino acid metabolic pathways constitute integral parts of the plant immune system. Mutations in several genes involved in Asp‐derived amino acid biosynthetic pathways can have profound impact on plant resistance to specific pathogen types. For instance, amino acid imbalances associated with homoserine or threonine accumulation elevate plant immunity to oomycete pathogens but not to pathogenic fungi or bacteria. The catabolism of Lys produces the immune signal pipecolic acid (Pip), a cyclic, non‐protein amino acid. Pip amplifies plant defence responses and acts as a critical regulator of plant systemic acquired resistance, defence priming and local resistance to bacterial pathogens. Asp‐derived pyridine nucleotides influence both pre‐ and post‐invasion immunity, and the catabolism of branched chain amino acids appears to affect plant resistance to distinct pathogen classes by modulating crosstalk of salicylic acid‐ and jasmonic acid‐regulated defence pathways. It also emerges that, besides polyamine oxidation and NADPH oxidase, Pro metabolism is involved in the oxidative burst and the hypersensitive response associated with avirulent pathogen recognition. Moreover, the acylation of amino acids can control plant resistance to pathogens and pests by the formation of protective plant metabolites or by the modulation of plant hormone activity.     

植物脂肪酸调控基因工程研究

脂肪酸代谢是植物最重要的代谢途径之一,脂肪酸在人们日常生活及工业生产上有重要用途,作者阐明了植物脂肪酸代谢的基本途径,并对近些年来植物脂肪酸代谢的遗传调控及基因工程的研究进展做了较为详细的总结,同时对植物脂肪酸调控基因工程发展提出了展望。     

Where does indolylacrylic acid come from

Summary In addition to the main catabolic routes of tryptophan (Trp), there exist minor and less thoroughly investigated pathways; one of these leads to indolylacrylic acid (IAcrA). IAcrA is a plant growth hormone, whereas its biological role in animals is still obscure, as is the way and site where it is formed in the organism. A two-stage production is likely: Intestinal microorganisms catabolize Trp to indole derivatives which are then absorbed and converted to IAcrA and its glycine conjugate, indolylacryloylglyeine (IAcrGly). Our finding of IAcrGly in the urine of proven germ-free piglets points to the possibility that Trp can be converted to IAcrA without the intervention of intestinal microorganisms. Seasonal and age variations, influence of light and connection with photodermatoses have been reported. Besides other pathological conditions the differences in IAcrGly excretion relative to normal controls were especially pronounced in some myopathies, namely in boys with Duchenne muscular dystrophy.     

Jasmonic acid and salicylic acid activate a common defense system in rice

Jasmonic acid (JA) and salicylic acid (SA) play important roles in plant defense systems. JA and SA signaling pathways interact antagonistically in dicotyledonous plants, but, the status of crosstalk between JA and SA signaling is unknown in monocots. Our rice microarray analysis showed that more than half of the genes upregulated by the SA analog BTH are also upregulated by JA, suggesting that a major portion of the SA-upregulated genes are regulated by JA-dependent signaling in rice. A common defense system that is activated by both JA and SA is thus proposed which plays an important role in pathogen defense responses in rice.     

Acetylsalicylic acid induces programmed cell death in Arabidopsis cell cultures

Acetylsalicylic acid (ASA), a derivative from the plant hormone salicylic acid (SA), is a commonly used drug that has a dual role in animal organisms as an anti-inflammatory and anticancer agent. It acts as an inhibitor of cyclooxygenases (COXs), which catalyze prostaglandins production. It is known that ASA serves as an apoptotic agent on cancer cells through the inhibition of the COX-2 enzyme. Here, we provide evidences that ASA also behaves as an agent inducing programmed cell death (PCD) in cell cultures of the model plant Arabidopsis thaliana, in a similar way than the well-established PCD-inducing agent H(2)O(2), although the induction of PCD by ASA requires much lower inducer concentrations. Moreover, ASA is herein shown to be a more efficient PCD-inducing agent than salicylic acid. ASA treatment of Arabidopsis cells induces typical PCD-linked morphological and biochemical changes, namely cell shrinkage, nuclear DNA degradation, loss of mitochondrial membrane potential, cytochrome c release from mitochondria and induction of caspase-like activity. However, the ASA effect can be partially reverted by jasmonic acid. Taking together, these results reveal the existence of common features in ASA-induced animal apoptosis and plant PCD, and also suggest that there are similarities between the pathways of synthesis and function of prostanoid-like lipid mediators in animal and plant organisms.     

Salicylic acid and its function in plant immunity

The small phenolic compound salicylic acid (SA) plays an important regulatory role in multiple physiological processes including plant immune response. Significant progress has been made during the past two decades in understanding the SA-mediated defense signaling network. Characterization of a number of genes functioning in SA biosynthesis, conjugation, accumulation, signaling, and crosstalk with other hormones such as jasmonic acid, ethylene, abscisic acid, auxin, gibberellic acid, cytokinin, brassinosteroid, and peptide hormones has sketched the finely tuned immune response network. Full understanding of the mechanism of plant immunity will need to take advantage of fast developing genomics tools and bioinformatics techniques. However, elucidating genetic components involved in these pathways by conventional genetics, biochemistry, and molecular biology approaches will continue to be a major task of the community. High-throughput method for SA quantification holds the potential for isolating additional mutants related to SA-mediated defense signaling.     

Rosmarinic acid and its derivatives: biotechnology and applications

Rosmarinic acid (RA) is one of the first secondary metabolites produced in plant cell cultures in extremely high yields, up to 19% of the cell dry weight. More complex derivatives of RA, such as rabdosiin and lithospermic acid B, later were also obtained in cell cultures at high yields. RA and its derivatives possess promising biological activities, such as improvement of cognitive performance, prevention of the development of Alzheimer’s disease, cardioprotective effects, reduction of the severity of kidney diseases and cancer chemoprevention. The TNF-α-induced NF-κB signaling pathway has emerged as a central target for RA. Despite these impressive activities and high yields, the biotechnological production of these metabolites on an industrial scale has not progressed. We summarized data suggesting that external stimuli, the Ca²⁺-dependent NADPH oxidase pathway and processes of protein phosphorylation/dephosphorylation are involved in the regulation of biosynthesis of these substances in cultured plant cells. In spite of growing information about pathways regulating biosynthesis of RA and its derivatives in cultured plant cells, the exact mechanism of regulation remains unknown. We suggest that further progress in the biotechnology of RA and its derivatives can be achieved by using new high-throughput techniques.     

植物激素ABA调控植物根系生长的研究进展

脱落酸（abscisic acid,ABA）是一种重要的植物激素,在调控种子发育、种子休眠与萌发、抑制生长、促进落花落果、参与植物应对外界环境胁迫等过程中发挥着重要的生理功能。ABA还能与其他植物激素（如生长素、乙烯等）互作进而精细调控植物根系的生长。本文以模式植物拟南芥（Arabidopsis thaliana（L.）Heynh）为主要对象,对近年来国内外在ABA调控植物根系生长方面的研究成果、ABA与其他植物激素（如GA等）互作调控根系生长及调控非生物逆境下根系发育的机理等进行综述,并对其未来的研究方向进行了展望。