Alkaloidal components in the poisonous plant,Ipomoea carnea (Convolvulaceae)

Natural intoxication of livestock by the ingestion of Ipomoea carnea (Convolvulaceae) sometimes occurs in tropical regions of the world. Polyhydroxylated alkaloids were isolated from the leaves, flowers, and seeds of the poisonous plant and characterized. Chromatographic separation of the leaf extract resulted in the isolation of swainsonine (1), 2-epi-lentiginosine (2), calystegines B(1) (3), B(2) (4), B(3) (5), and C(1) (6), and N-methyl-trans-4-hydroxy-l-proline (7). The contents of 1 in the fresh leaves and flowers were 0.0029 and 0.0028%, respectively, whereas the contents of 1, 3, and 4 in the seeds were approximately 10 times higher than those in the leaves and flowers. Alkaloids 3, 4, and 6 showed a potent inhibitory activity toward rat lysosomal beta-glucosidase, with IC(50) values of 2.1, 0.75, and 0.84 microM, respectively, and alkaloid 5 was a moderate inhibitor of alpha- and beta-mannosidases. Although alkaloid 1 is known as a powerful inhibitor of lysosomal alpha-mannosidase (IC(50) = 0.02 microM), alkaloid 2, which has been thought to be an intermediate in the biosynthesis of 1, was also a potent inhibitor of alpha-mannosidase with an IC(50) value of 4.6 microM.     

Alkaloids from the poisonous plant Ipomoea carnea: effects on intracellular lysosomal glycosidase activities in human lymphoblast cultures

There is natural intoxication of livestock by the ingestion of Ipomoea carnea (Convolvulaceae) in Brazil and other parts of the world. The alkaloidal glycosidase inhibitors swainsonine, 2-epi-lentiginosine, and calystegines B(1), B(2), B(3), and C(1) have been identified as constituents of this plant. Swainsonine is a potent inhibitor of rat lysosomal alpha-mannosidase, with an IC(50) value of 0.02 microM, whereas calystegines B(1), B(2), and C(1) are potent inhibitors of rat lysosomal beta-glucosidase, with IC(50) values of 2.1, 0.75, and 0.84 microM, respectively. The action of swainsonine results in a lysosomal storage disorder that closely mimics alpha-mannosidosis in humans. To determine whether the toxicity of I. carnea to livestock is due to purely swainsonine or due to a combination of effects by swainsonine and calystegines, intracellular lysosomal glycosidase activities in normal human lymphoblasts grown with inhibitors in the medium were examined. Incubation of lymphoblasts with 0.1 microM swainsonine for 3 days resulted in approximately 60% reduction of alpha-mannosidase activity. On the other hand, calystegines B(2) and C(1) showed no inhibition of beta-glucosidase up to 1 mM; instead inclusion of calystegines B(2) and C(1) at 100 microM in the culture medium increased its activity by 1.5- and 1.6-fold, respectively. Calystegines B(2) and C(1) seem to act as chemical chaperones, enhancing correct folding of the enzyme and enabling smooth trafficking to the lysosome. The lysosomal beta-glucosidase inhibitory calystegines seem to have little risk of inducing intoxication of livestock.     

Potential therapeutic applications of some antinutritional plant secondary metabolites

Plant-based formulations have been used since ancient times as remedial measures against various human and animal ailments. Over the past 20 years interest in traditional medicines has increased considerably in many parts of the world. Whereas modifications in lifestyles, including diet, have had a profound effect on the increased risks of various diseases, there is considerable scientific evidence, both epidemiological and experimental, regarding vegetables and fruits as key features of diets associated with reduced risks of diseases such as cancers and infections. This has led to the use of a number of phytometabolites as anticarcinogenic and cardioprotective agents, promoting a dramatic increase in their consumption as dietary supplements. There are changing perceptions regarding the therapeutic potential of various plant secondary metabolites (PSMs), some of which have also been known to possess certain antinutritional qualities. The knowledge gained at the cellular and molecular levels, and biological activities of PSMs including tannin-polyphenols, saponins, mimosine, flavonoids, terpenoids, and phytates, would be useful in planning for future epidemiological studies and human cancer prevention trials, especially when a large pure dosage is not the option to deliver the active compounds to many tissues. It is well observed that alteration of cell cycle regulatory gene expression is frequently found in tumor tissues or cancer cell lines, and studies have suggested that the herbal-based or plant-originated cell cycle regulators might represent a new set of potential targets for anticancer drugs. The recent upsurge of interest in this area of research and advances made therein indicate that the impact of a number of diseases affecting humans and animals may be lessened, if not prevented, by simple dietary intake of PSMs with putative therapeutic properties.     

Evaluation of the potential of fungal and plant laccases for active-packaging applications

Laccases from Trametes versicolor (TvL), Myceliophthora thermophila (MtL), and Rhus vernicifera (RvL) were investigated with regard to their potential utilization as oxygen scavengers in active packages containing food susceptible to oxidation reactions. The substrate selectivity of the laccases was investigated with a set of 17 reducing substrates, mainly phenolic compounds. The temperature dependence of reactions performed at low temperatures (4-31 °C) was studied. Furthermore, the laccases were subjected to immobilization in a latex/clay matrix and drying procedures performed at temperatures up to 105 °C. The results show that it is possible to immobilize the laccases with retained activity after dispersion coating, drying at 75-105 °C, and subsequent storage of the enzyme-containing films at 4 °C. TvL and, to some extent, MtL were promiscuous with regard to their reducing substrate, in the sense that the difference in activity with the 17 substrates tested was relatively small. RvL, on the other hand, showed high selectivity, primarily toward substrates resembling its natural substrate urushiol. When tested at 7 °C, all three laccases retained >20% of the activity they had at 25 °C, which suggests that it would be possible to utilize the laccases also in refrigerated food packages. Coating and drying resulted in a remaining enzymatic activity ranging from 18 to 53%, depending on the drying conditions used. The results indicate that laccases are useful for active-packaging applications and that the selectivity for reducing substrates is an important characteristic of laccases from different sources.     

植物营养生物学研究方向探讨

植物营养生物学是重点研究植物活化、吸收、转运与利用养分的生理、分子及遗传机制的科学。在过去的30年,我国植物营养生物学研究取得了长足的发展,但从国家自然科学基金资助情况分析,与相关学科相比,近10多年来植物营养生物学总体研究力量相对薄弱,缺乏新一代领军人才。一些研究更接近于“纯”植物生物学,与植物营养应用研究出现脱节,对农业绿色发展及化肥产业升级的支撑不够。植物营养生物学研究者应该重视与作物育种、耕作栽培、生态环境、植物保护及化肥产业的合作,跟踪这些领域的研究现状及生产中面临的技术需求,围绕这些领域的技术“瓶颈”开展植物营养基础研究,在提供解决途径的同时创新植物营养生物学机理,从而丰富植物营养学理论。在研究内容上,建议重视控制养分响应度的生理与遗传机制,养分信号与环境信号互作,养分×土壤×管理互作及其对根系生长的影响,养分供应与抗生物胁迫,高产高效的植物营养生理学基础,特种作物的营养机理,化肥产品升级的生物学途径等方向的研究。     

中国农业科学院植物营养与肥料研究60年

中国农业科学院植物营养与肥料研究经历了60年的发展历程。按照研究的重点,可大致可分为四个阶段,第一阶段为1980年之前的单一肥料肥效研究阶段,该阶段主要研究单一养分的肥料效应,为我国化学肥料工业发展提供了依据;第二个阶段是1980年至1990年,该阶段主要研究了氮磷钾营养元素的配合肥效与主要配合方式,为我国复合肥料的引进和发展提供了理论基础;第三阶段是1990年至2000年,该阶段主要进行平衡施肥技术研究,同时研究了中微量元素的肥料效应;2000年以后是第四阶段,该阶段可称为养分综合管理阶段,该阶段重点研究了精准施肥技术、测土配方施肥支撑技术、施肥与环境、新型肥料及节肥增效关键技术等,这些研究为保证我国粮食安全作出了重大贡献。     

植物系统获得抗病性研究进展

简述了近年来国内外植物系统获得抗病性的研究现状，特别对系统性抗病性的生理生化机理及信号传导机理进行了评价，展示了新的化学诱导物质的应用研究状况与前景。     

A survey of plant analysis interpretations and applications in the United States

Abstract

A survey was conducted of 55 state and 371 commercial laboratories throughout the United States in order to document the current applications of plant analyses and the extent of application of the diagnosis and recommendation integrated system (DRIS) and to identify factors that have hindered or facilitated the implementation of the DRIS. State labs listed “research”; and commercial labs listed “diagnosis of nutrient deficiencies”; as the most common uses for plant analyses. Plant analysis results were widely used in combination with soil tests when diagnosing nutrient deficiencies and recommending corrective action (96% of state labs and 92% of commercial labs diagnosing nutrient deficiencies). Nationwide, the sufficiency range was the most commonly identified method of interpreting plant analyses (61% of the state and 58% of the commercial labs). The DRIS was used more extensively in the North Central region (14 labs) than in any other region. The two most commonly identified factors hindering the implementation of the DRIS were 1) lack of field verification and/or calibration and correlation data and, 2) unfamiliarity with the system. Computer availability appears to be the most important factor facilitating the implementation of the DRIS.     

铜胁迫对植物生长发育影响与植物耐铜机制的研究进展

铜(Cu)是植物生长发育必需的微量营养元素,在光合作用、呼吸作用、抗氧化系统及激素信号转导等多种生理过程中发挥至关重要的作用,其在植物体内含量过高或不足均会影响植物的正常生理代谢。近年来由于含铜杀菌剂的广泛使用及工业含铜污染物的排放,铜污染对植物生长发育的危害备受关注。研究铜离子对植物生长发育的影响以及植物响应铜胁迫的分子机制,对人们了解植物的耐铜性和铜污染区的植物修复具有重大意义。本文从植物对铜离子的吸收转运及积累,铜胁迫对植物生长发育的影响及植物对铜胁迫的抗性机制3个方面,系统总结了国内外关于植物铜胁迫的研究进展,并提出了需要进一步加强铜胁迫分子调控机制及植物修复方面的研究。     

碳纳米管在作物研究中的应用进展与分析

碳纳米管在农作物研究中的应用对象已经涵盖了大米、玉米、小麦、番茄、葡萄等常见的农作物。由于研究目的不同,使用的碳纳米管种类、分散方式、浓度也不同,导致文献中出现了试验结果多样化的问题。为了建立一个较为统一的碳纳米管试验框架,该研究首先以作物培育、抗逆、生理指标监测和农业基因工程为纲,对碳纳米管在作物研究中的应用进展进行了综述,并归纳了文献中使用的碳纳米管参数及其应用效果。通过综合分析,论证了作物研究中存在碳纳米管有效浓度未知、特异性作用不明显、间接生物毒性研究不足的问题,并针对性地给出了作物研究中的碳纳米管试验方案建议,包括碳纳米管的选型、培养基的制备以及表征方法。最后,与以往利用原始和共价修饰的碳纳米管进行作物培育不同,在未来,利用非共价修饰的碳纳米管或碳纳米管的非共价堆积作用进行作物研究是重要的发展方向。     

植物磷转运子 PHT1 家族研究进展

【目的】磷是植物生长发育所必需的大量营养元素。植物 PHT1 磷转运蛋白家族在植物磷吸收、运转及再利用等过程中发挥了重要作用。迄今已在多种高等植物中相继分离出大量 PHT1 家族基因。本文综述了国内外关于植物 PHT1 家族的主要研究进展,详细阐述了植物 PHT1 家族的表达模式、功能及可能的调控途径。 主要进展植物 PHT1 家族属于 MFS (major facilitator superfamily) 超家族,不同物种 PHT1 家族蛋白的结构非常保守,通常具有 12 个亲脂跨膜结构域,形成“6 螺旋–亲水大环–6 螺旋”式的结构镶嵌于质膜当中。同时,该家族具有 H₂PO₄–/nH+ 共运子、糖转运子和 MFS 通用转运子等特征结构域和一段保守的氨基酸特征序列 GGDYPLSATIMSE。一般情况,植物 PHT1 家族基因吸收转运 1 个无机磷需要 2～4 个质子协同进入质膜,并伴随膜电位的变化。植物 PHT1 家族的磷转运特性差异较大,其动力学参数 Km 值差别较大。高等植物 PHT1 家族成员众多。在拟南芥、水稻、大豆、茄科植物及其他物种中的研究发现,PHT1 家族各成员间的时空表达模式存在差异,多数成员受低磷信号调控且主要在根部表达,少部分成员在除根以外的其他器官中表达,并行使相应的磷转运功能。已有研究表明,植物 PHT1 家族基因的转录水平受到多因素的调控,例如外界环境中的无机磷浓度,转录因子如 MYB 家族、WRKY 家族以及 ZAT6 等基因能与 PHT1 家族基因启动子区的特殊调控元件如 MYCS 元件、P1BS 元件及 W-box 元件等结合,调控基因的转录。此外,部分 PHT1 家族基因的转录水平受丛枝菌根真菌 (arbuscular mycorrhizal fungi,AMF) 的调控。除了转录水平的调控,关于植物 PHT1 家族转录后水平的调控途径同样取得了较大进展。PHF1 基因、含 SPX 结构域的蛋白家族、MicroRNA、蛋白磷酸化与去磷酸化、染色质修饰及其他等一系列调控途径均参与到 PHT1 家族基因的转录后调控及信号转导。植物激素如生长素、乙烯和细胞分裂素等也参与这一调控过程。 建议与展望植物对磷吸收利用的分子调控机理及信号转导途径十分复杂,因此,培育磷高效利用基因型作物任重而道远。关于植物 PHT1 家族基因的研究已从模式植物向作物及其他高等植物中扩展,然而对该家族蛋白的生化及结构生物学等研究还待进一步深入。同时,对于一些基因组较复杂的多倍体物种如甘蓝型油菜、小麦、大麦及棉花等,仍有待开展进一步研究。     

大型有毒真菌的资源及其抗虫活性的研究进展

大型有毒真菌是指子实体被食用后对人类或动物产生中毒反应的大型真菌。许多大型有毒真菌具有抗虫活性．在未来新型生物源农药的研制与开发中具有巨大的潜力。文章对具有抗虫活性的大型有毒真菌资源及其抗虫活性的研究现状进行综述，并提出了目前研究中存在的问题和需要重点突破的关键技术。     

植物耐盐生理生化研究进展

综述了近年来耐盐植物地上部分K /Na ,SNa ·K 渗透调节 ,光合作用 ,盐激蛋白 ,Na /H 逆向转运蛋白 ,激素调节 ,膜抗氧化酶和ATP酶等方面耐盐性生理生化研究进展及其对选育培育耐盐植物新品种的重要性。     

纳米材料在土壤与植物营养领域的应用进展

将纳米技术应用于土壤与植物营养领域是该领域研究的一个新的突破,有可能解决肥料利用率、作物增产与环境污染等诸多问题.在总结了国内外纳米技术在土壤与植物营养领域应用研究的基础上,重点分析了纳米材料在土壤环境、抗菌及肥料方面的应用现状、分析方法和机理,指出了优点和不足,并进行了展望,以期对纳米技术在土壤肥料与植物营养领域上的应用有一个总体认识,也为该领域进行深入研究拓展新的思路.     

植物试管苗离体生根研究进展

综述了植物试管苗生根机理方面的基因表达和遗传转化,内源激素和酶类活性与生根的关系;培养基组成物矿物盐类、附加有机成分(维生素和氨基酸)、生长调节物质、蔗糖、琼脂、活性碳、酚类物质,及pH值,培养条件、通气、湿度、温度和光照对试管苗生根的影响;外植体基因型与插条生理和发育状态与生根的关系,为植物组织培养试管苗生根研究提供一定的参考.     

植物吸收利用钾素研究的某些进展

钾的研究是植物营养研究中最重要的内容之一。本综述了植物营养研究在K^ 吸收机理，K^＋吸收影响因素及植物钾素营养基因型差异等方面的研究进展。     

白头叶猴采食植物的再研究

2006年使用了较先进的录像设备,结合单筒望远镜对白头叶猴进行了全天候的跟踪观察和录像,使我们有可能更准确地仔细鉴定白头叶猴采食的植物及采食部位,也为动物生态的研究提供一个可重复验证的方法。经统计分析发现:白头叶猴属热带分布的灵长类动物,全以植物的各部分器官为食;被采食的植物大多数为热带分布的物种,是当地植被重要的建群种或优势种;在白头叶猴采食的物种中,有一部分是人类使用的药用植物;其中落叶成分和喜钙植物都较多;初步认为白头叶猴对不同的植物其喜食程度有明显不同。     

Basic strategies of molecular biological research in plant nutrition - a review

A review is given on basic methodical strategies of molecular biological research in plant nutrition. Membrane transport protein identification and analysis by the use of cDNA libraries and functional expression in yeast mutants and Xenopus oocytes is demonstrated. The various methods of gene isolation and analysis, including molecular data of model plants, are pointed out. The significance of research on transgenic plants permitting overexpression of introduced genes, antisense technique and analysis of promoter/reporter gene constructs is emphasized. The numerous examples of recent research simultanously indicate contemporary and future topics for molecular biological research in plant nutrition.     

沙棘“柔性坝”对土壤水分调控作用的试验研究

沙棘植物“柔性坝”拦沙淤积效果明显，为了探求沙棘“柔性坝”对土壤水分的调控作用，在内蒙古准格尔旗西召沟东一支沟小流域内对5座沙棘“柔性坝”开展了野外试验研究，同时在东一支沟左岸一未种植沙棘“柔性坝”的小支沟进行了对比试验。沿沟道及“柔性坝”坝体纵向设置若干断面，每个断面设2～3个采样点，每个采样点在1 m深度范围内分9层采集土样测定土壤含水率。试验结果表明：降雨后，沙棘“柔性坝”坝体土壤水分的垂向分布呈现降低型(土壤含水率随土层深度的增加而降低)；而对比沟各断面的土壤含水率的垂向分布则为增长型或波动型。这表明沙棘“柔性坝”有利于雨水下渗和增加土壤含水率，进而起到保水固土和促进植被生长的作用。从“柔性坝”坝体中部至上游淤积体，平均土壤含水率呈现纵向递增趋势；并基于达西定律探讨了断面平均土壤含水率与纵向距离之间的关系。