不同土壤水分和养分条件下喜旱莲子草与同属种生长状况的比较研究

喜旱莲子草(Alternanthera philoxeroides)入侵已在中国造成巨大的生态和经济损失。为揭示喜旱莲子草成功入侵的生态机制并预测其种群扩张趋势及其与环境因子的关系, 作者比较了喜旱莲子草与其同属的外来弱入侵种刺花莲子草(A. pungens)以及土著种莲子草(A. sessilis)在不同土壤水分、养分条件下的生长状况。结果显示: 在高水高肥条件下, 喜旱莲子草的生物量要高于刺花莲子草和莲子草, 而在低水低肥条件下却不如这两个同属种; 弱入侵种刺花莲子草在低水条件下的生物量要高于强入侵种喜旱莲子草和土著种莲子草, 说明植物的入侵性受环境条件的影响。另外, 强入侵种喜旱莲子草形态学性状的可塑性较高, 在各种条件下都具有较高的比叶面积, 暗示这两个指标可作为莲子草属外来植物入侵性的预测指标。     

不同生境下空心莲子草响应模拟昆虫采食的生长和化学防御策略

外来植物往往可以入侵多种生境并受到多种昆虫的采食,而不同生境条件将可能会影响这些入侵植物对昆虫采食的防御策略。以入侵我国的克隆植物——空心莲子草为研究对象,分别选择生长在水生生境、水陆两栖生境和陆生生境中的无性个体(分株),通过50%去叶处理模拟昆虫采食,分析不同生境下空心莲子草对模拟昆虫采食处理的生长及化学防御响应的差异。模拟昆虫采食处理显著抑制了陆生生境、水陆两栖生境以及水生生境下空心莲子草的根、茎、叶和总生物量,但对3种生境下空心莲子草的生物量分配(根冠比、根生物量分配、茎生物量分配和叶生物量分配)均无显著影响。陆生生境下空心莲子草根、茎和总生物量显著高于水陆两栖生境和水生生境,根冠比显著低于水陆两栖生境和水生生境。模拟昆虫采食处理显著降低了空心莲子草的木质素含量,而对单宁和总酚含量影响不显著。生境对木质素含量无显著影响,但陆生生境下空心莲子草单宁含量显著高于水陆两栖生境和水生生境,且总酚含量显著高于水陆两栖生境,表明陆生生境中空心莲子草具有更强的防御能力。空心莲子草木质素含量与总生物量无显著相关性,但在模拟采食情况下,其总酚含量与总生物量呈显著负相关,而无论模拟昆虫采食处理存在与否,空心莲子草单宁含量与总生物量均呈显著正相关。因此,空心莲子草存在昆虫介导的生长和化学防御之间的权衡,在昆虫采食的情况下可通过减少生长来增加对化学防御物质的投入,但生境对空心莲子草这种生长-防御权衡的影响十分有限。     

空心莲子草响应南方菟丝子寄生的生长-防御权衡

为探讨全寄生植物南方菟丝子(Cuscuta australis)防治入侵植物空心莲子草(Alternanthera philoxeroides)的可行性,以二者野外天然生长的种群为研究对象,分析南方菟丝子寄生对空心莲子草生长及防御的影响,阐明空心莲子草在受到寄生胁迫时如何权衡自身生长与防御的关系,进而发展出一套应对南方菟丝子寄生的生长-防御策略。结果显示:(1)南方菟丝子寄生显著改变空心莲子草茎的形态,茎直径和平均节间长均增加,茎直径变化极显著(P0.01);(2)南方菟丝子寄生显著减少空心莲子草叶片数,但同时显著增加后者茎的分枝数,而茎上的节是潜在的无性繁殖体,故有利于空心莲子草的克隆繁殖;此外,南方菟丝子寄生显著降低了空心莲子草的根、茎、叶生物量和总生物量,抑制空心莲子草的生长;(3)南方菟丝子寄生显著增加空心莲子草茎的单宁、总酚、三萜皂苷含量,增强其防御能力;(4)南方菟丝子寄生的空心莲子草的生物量与茎部木质素、三萜皂苷、单宁和总酚含量均呈现显著负相关性(P0.01),对照组则不存在相关性;且寄生组较对照组相比,生物量的相对百分比显著低于对照组(P0.01),而用于防御的次生代谢产物总含量的相对百分比显著高于对照组(P0.01)。以上结果表明,受到南方菟丝子寄生胁迫后,空心莲子草改变自身的生长-防御策略,减少营养生长投入而将更多的资源投向克隆繁殖,同时增强对"防御"物质的投入,增强其防御能力,以利于后代生存和繁衍。     

地上-地下植食性天敌对入侵植物空心莲子草与本地种莲子草种间关系的影响

生物入侵是全球生物多样性的主要威胁,外来种与本地种的种间竞争能力会影响其能否成功入侵。本研究选用入侵植物空心莲子草和其本地同属种莲子草为对象,探究其专食性天敌莲草直胸跳甲与南方根结线虫对空心莲子草与莲子草的生长及种间关系的影响。结果表明: 与无天敌胁迫相比,线虫处理显著降低了莲子草的株高(28.1%),但显著增加了空心莲子草的株高(52.8%)和莲子草的地上生物量(63.7%);跳甲处理显著降低了莲子草的株高(40.7%),对空心莲子草无显著影响;而跳甲与线虫的共同胁迫显著降低了莲子草的株高(35.3%)和空心莲子草的地下生物量(62.2%),显著增加了莲子草的地上生物量(69.1%);天敌胁迫对两种植物的茎粗、分枝数和根长均无显著影响。无天敌作用下,两种植物的相对邻体效应指数(RNE)均为正值,且空心莲子草的RNE比莲子草高21.3%;天敌胁迫下,空心莲子草的RNE均为负值,而莲子草的RNE在线虫或跳甲单独胁迫下为正值,在线虫和跳甲共同胁迫下为负值。表明地上-地下天敌互作可以使两种植物的种间关系发生改变,并可能促进空心莲子草的入侵。     

重金属胁迫条件下空心莲子草的生长和营养特征分析

空心莲子草是一种常见的水生植物,并能在重金属污染的水体或附近土壤中生长.本研究发现,空心莲子草能富集6种常见的重金属元素,其富集能力为:Zn2+>Mn2+>Pb2+>Cu2+>Cd2+>Cr3+.高浓度(1 mmol/L) Cu2+、Mn2+、Zn2+和Cr3+ 等重金属胁迫处理条件下,空心莲子草的根冠比增加,生物干重、总根长和总根表面积都相应降低.此外,高浓度(1 mmol/L) Pb2+、Cd2+、Cu2+或Zn2+分别胁迫处理条件下,空心莲子草的K+、Ca+和Mg+等元素的含量变化差异显著(P＜0.05).以上研究表明,空心莲子草通过改变体内钾钙镁等重要生长元素营养情况来适应重金属污染的胁迫,有很强的富集重金属元素的能力,进而降低污染、净化水体.空心莲子草对重金属污染的生长响应及体内重要矿物元素营养特性之间的相互关系,可能为重金属污染的水土生物修复提供理论依据.     

空心莲子草具有较强抗盐能力的原因初探

为了探讨空心莲子草(Alternantheraphiloxeroides(Mart.)Griseb)的抗盐机理,测定了盐胁迫条件下的空心莲子草和水稻中保护酶活性和渗透调节物质的变化。结果表明,在盐胁迫下,空心莲子草中的脯氨酸、甜菜碱以及SOD、POD等含量增加速度比水稻快,膜脂过氧化产物丙二醛的含量在两种植物中虽亦增加,但在空心莲子草叶中的增加幅度小于水稻。证明盐胁迫下保护酶活性和渗透调节物质含量的迅速增加是空心莲子草具有较强抗盐能力的重要生理学基础。     

干旱胁迫对空心莲子草抗氧化酶活性和组织学的影响

目的:空心莲子草是一种水旱两栖植物,对其抗旱性的研究越来越受到重视。初步探讨空心莲子草的抗旱机理,为进一步的分子生物学实验奠定基础。方法:采用干旱胁迫的方法,测定空心莲子草的根和叶中抗氧化酶类(SOD、POD、CAT等)的活性变化,并对其组织学的变化进行分析比较。结果:在干旱胁迫下,空心莲子草总抗氧化能力一直增大,抗氧化酶活性是先增大后减小。干旱胁迫下根中抗氧化酶的活性比叶中的活性要高,总抗氧化能力也较强。经组织学比较发现,干旱胁迫后根和叶的组织细胞变小,并有少量细胞坏死。结论:空心莲子草具有较强的抗旱性,表现在干旱胁迫时根和叶能合成大量的抗氧化酶以抵抗干旱胁迫给机体带来的伤害作用,并且总抗氧化能力一直处于较高的水平。     

Effects of elevated temperature on chemistry of an invasive plant,its native congener and their herbivores

增温对莲子草属入侵植物与本地同属植物化学物质组成和天敌昆虫的影响 气候变暖影响植物生长和生理活动,然而气候变暖如何改变入侵植物化学物质组成并间接影响其与植食性昆虫互作还少有报道。本研究以入侵植物空心莲子草(Alternanthera philoxeroides)及其本地同属 植物莲子草(A. sessilis)为对象,探究增温对其叶片化学物质组成的影响并进一步检验这些变化如何影响两 种植食性昆虫虾钳菜披龟甲(Cassida piperata)和斜纹夜蛾(Spodoptera litura)的生长发育。通过模拟增温实验,探究增温对空心莲子草和莲子草13个叶片化学物质的影响,并用其饲养两种植食性昆虫,测量它们的生长和发育时间。研究结果显示,增温显著改变了空心莲子草和莲子草叶化学物质组成;增温降低了空心莲子草叶片氮浓度,增加了莲子草叶片总黄酮和总酚浓度;增温对其它营养物质(果糖、蔗糖、总可溶性糖和淀粉)随物种和具体物质发生改变;采用增温处理的莲子草饲养的虾钳菜披龟甲蛹重和斜纹夜蛾幼虫重量,以及增温处理的空心莲子草饲养的斜纹夜蛾幼虫重量,显著低于对照不增温处理;此外,采用增温处理的莲子草饲养的斜纹夜蛾幼虫发育时间显著延长。这些结果表明,增温对植物化学物质组成的影响随物种发生变化,增温对入侵植物和本地植物化学物质组成的影响间接改变了其与植食性昆虫的互作关系。     

Ca~(2+)和K~+对拟南芥幼苗镉毒害的缓解作用

该文探讨了外源钙(Ca)或钾(K)处理对不同程度的镉(Cd)胁迫(0–80μmol·L–1)下拟南芥(Arabidopsis thaliana)幼苗的生长和生理特性的影响。综合Ca和K对不同浓度Cd胁迫下拟南芥幼苗生长、根长以及生物量的影响情况,表明各浓度Cd胁迫下外源Ca2+的最适缓解浓度均为10 mmol·L–1;而K+的最适缓解浓度在低浓度(20和40μmol·L–1)和高浓度(60和80μmol·L–1)Cd胁迫下分别为10 mmol·L–1和20 mmol·L–1。在低浓度Cd胁迫下,添加适宜浓度的Ca2+或K+后幼苗可溶性蛋白和丙二醛(MDA)含量以及超氧化物歧化酶(SOD)活性相比未添加Ca和K的对照组无显著变化,而过氧化物酶(POD)活性和总酚、类黄酮、花色素苷,酸溶性硫醇化合物、谷胱甘肽(GSH)、植物螯合肽(PCs)的含量均下降;高浓度Cd处理下,添加适宜浓度的Ca2+或K+后幼苗的SOD活性升高,POD活性降低,可溶性蛋白、MDA、总酚、类黄酮、花色素苷、酸溶性硫醇化合物、GSH以及PCs的含量也均低于对照组。在各浓度Cd胁迫下,添加外源Ca或K均使拟南芥幼苗根部细胞DNA损伤减弱,表现为TT嘧啶二聚体的累积量显著减少(P0.05)。以上结果表明,在Cd胁迫(尤其是高浓度Cd胁迫)下,外源Ca或K通过调节酚类、金属螯合物质的代谢水平以及提高拟南芥的抗氧化能力来缓解Cd对拟南芥幼苗的毒害效应,缓解细胞DNA损伤。该研究结果不仅能够为深入探讨Ca和K对缓解重金属毒害的分子机理提供实验依据,而且为Ca和K应用于重金属污染的防治提供参考。     

完全水淹条件下空心莲子草的生长、存活及出水后的恢复动态研究

为了判断入侵植物空心莲子草(Alternanthera philoxeroides)能否在河岸带的水淹环境中生存,实验研究了空心莲子草在30、60、90 d和120 d的完全水淹条件下的形态变化、生物量变化、存活及出水后的恢复生长状况.结果发现,空心莲子草在完全水淹条件下分枝的伸长生长加剧,并能快速产生新的叶片,但总生物量及地下部分生物量显著降低.空心莲子草在完全水淹处理后有很高的存活率,淹没120 d后存活率仍高达90%.水淹处理结束后,植株能够迅速地开始恢复生长,但恢复生长能力随着水淹持续时间的延长而逐渐降低.结果表明,空心莲子草有很强的水淹耐受能力,能够在江河河岸带生存,但在水淹持续时间较长的距水面较近的地段可能生长较差.     

Characterization of SSEA-1 glycolipids from the brain of a patient with fucosidosis

Neutral glycolipids from the brain of a patient with Fucosidosis were analyzed and two complex glycolipids containing five and eight sugars were isolated from the cortical grey matter. These two glycolipids reacted with antibodies recognizing the SSEA-1 [Le^x(X)] carbohydrate determinant. SSEA-1 glycolipids are normally expressed in human embryonic brain but are found in only small amounts in postnatal human brain. The accumulation of the two SSEA-1 glycolipids in Fucosidosis brain thus represents a defect which affects the normal developmentally regulated decrease in postnatal, expression of these glycolipids, and may be a contributing factor in the abnormal brain development associated with the disease. Chemical characterization of the two isolated glycolipids by gas chromatographic and mass spectrometric analyses has identified the two glycolipids as lacto-N-fucopentaosylceramide (III) and difucosyl-neolactonorhexaosylceramide.Abbreviations DCl direct chemical ionization - FAB tastatiom bombardment - GC gas chromatography - GSLs glycosphingolipids - MS mass spectrometry - SSEA-1 stage specific embryonic antigen-1 - TLC thin layer chromatographys     

Elucidation of Structure of Lipid A from the Marine Gram-Negative Bacterium Pseudoalteromonas haloplanktis ATCC 14393T

The chemical structure of lipid A, from the marine -proteobacterium Pseudoalteromonas haloplanktis 14393, a main product of lipopolysaccharide hydrolysis (1% AcOH), was determined using chemical methods and NMR spectroscopy. The lipid A was shown to be -1,6-glucosaminobiose 1,4-diphosphate acylated with two (R)-3-hydroxyalkanoic acid residues at C3 and C3 and amidated with one (R)-3-hydroxydodecanoyl and one (R)-3-dodecanoyloxydodecanoyl residue at N2 and N2, respectively.     

Structural Peculiarities of Na+,K+-ATPase Isozymes from the Calf Brain

Functionally active preparations of Na⁺,K⁺-ATPase isozymes from calf brain that contain catalytic subunits of three types (1, 2, and 3) were obtained using two approaches: a selective removal of contaminating proteins by the Jorgensen method and a selective solubilization of the enzyme with subsequent reconstitution of their membrane structure by the Esmann method. The ouabain inhibition constants were determined for the isozymes. The real isozyme composition of the Na⁺ pump from the grey matter containing glial cells and the brain stem containing neurons was determined. The plasma membranes of glial cells were shown to contain mainly Na⁺,K⁺-ATPase of the 11 type and minor amounts of isozymes of the 22(1) and the 31(2) type. The axolemma contains 21 and 31 isozymes. A carbohydrate analysis indicated that 11 enzyme preparations from the brain grey matter substantially differ from the renal enzymes of the same composition in the glycosylation of the 1 isoform. An enhanced sensitivity of the 3 catalytic subunit of Na⁺,K⁺-ATPase from neurons to endogenous proteolysis was found. A point of specific proteolysis in the amino acid sequence PNDNR⁴⁹² Y⁴⁹³ was localized (residue numbering is that of the human 3 subunit). This sequence corresponds to one of the regions of the greatest variability in 1-, 2-, 3-, and 4-subunits, but at the same time, it is characteristic of the 3 isoforms of various species. The presence of the 3 isoform of tubulin (cytoskeletal protein) was found for the first time in the high-molecular-mass Na⁺,K⁺-ATPase 31 isozyme complex isolated from the axolemma of brain stem neurons, and its binding to the 3 catalytic subunit was shown.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Systematic significance of mature embryo of bamboos

The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.     

Identification of novel oocyte and granulosa cell markers

Here we present novel gene expression patterns in the ovary as part of an ongoing assessment of published micro-array data from mouse oocytes and embryos. We present the expression patterns of 13 genes that had been determined by micro-array to be expressed in the mature egg, but not during subsequent preimplantation development. In-situ hybridization of sectioned ovaries revealed that these genes were expressed in one of two distinct patterns: (1) oocyte-specific or (2) expressed in both the oocyte and surrounding granulosa cells. Despite the fact that micro-array data demonstrated expression in the egg, several of these genes are expressed at low levels in the oocyte, but strongly expressed in granulosa cells. Eleven of these genes have no reported function or expression during oogenesis, indicating that this approach is a necessary step towards functional annotation of the genome. Also of note is that while some of these gene products have been well characterized in other tissues and cell types, others are relatively unstudied in the literature. Our results provide novel gene expression information that may provide insights into the molecular mechanisms of follicular recruitment, oocyte maturation and ovulation and will direct further experimentation into the role these genes play during oogenesis.     

N-andO-glycosylation of glycoprotein C synthesized by Herpes simplex virus type 1-infected ricin resistant cells

The progeny of Herpes simplex virus type 1 (HSV-1) grown in ricin-resistant 14 cells (Ric^R14) lackingN-acetylglucosaminyltransferase I was released in the extracellular medium at a very low rate. By using a monoclonal antibody immobilized on Sepharose we purified from HSV-1-infected Ric^R14 cells a viral glycoprotein (gC), which carries bothN-andO-linked oligosaccharides. Glycopeptides obtained from [³H]mannoselabeled gC by Pronase digestion were entirely susceptible to endo--N-acetylglucosaminidase H, and the major oligosaccharide released was Man₄GlcNAc. The accumulation of this high-mannose species was related to the enzymic defect of the host cells and to the long retention of the viral glycoprotein within the cells. The extent ofO-glycosylation evaluated in [¹⁴C]glucosamine-labeled gC from Ric^R14 cells as compared to that of gC from wild type cells did not appear to be significantly modified.Abbreviations Con A concanavalin A - BHK cells baby hamster kidney cells - HSV Herpes simplex virus