空心莲子草对南京春季杂草群落组成和物种多样性的影响

空心莲子草(Alternanthera philoxeroides)是目前我国危害最为严重的外来植物之一。利用样方法调查了南京市春季有空心莲子草分布的不同生境下杂草的种类和分布情况,用主成分分析及聚类分析法进行数据处理分析,目的是研究空心莲子草对杂草群落组成和物种多样性的影响。结果表明,南京市春季有空心莲子草分布的样点杂草有36科142种,其中禾本科、菊科、蓼科最多;影响空心莲子草及伴生杂草分布、发生的主要因素是土壤水分条件和人为干扰强度。依据这两个因素的不同,可将样点划分为4个聚类群,比较了各聚类群物种多样性指数,结果显示:各聚类群里随着空心莲子草重要值的升高,Simpson优势度指数也逐步上升,表明空心莲子草的优势度得到加强;Shannon-Weiner指数和Pielou均匀度指数均逐渐下降,说明了群落的物种多样性持续降低,原来的优势种危害加大,空心莲子草的入侵影响群落结构,使物种多样性降低。     

不同温度对七种外来杂草生理指标的影响及其适应意义

加拿大一枝黄花(Solidagocanadensis)、小飞蓬(Conyzacanadensis)、野塘蒿(Conyzabonarinsis)、钻形紫菀(Astersublatus)、一年蓬(Erigeronannuus)、马缨丹(Lantanacamara)和金鸡菊(Coreopsislanceolata)是我国东南地区有分布的7种外来杂草。测定了38°C、25°C和5°C处理下它们的可溶性糖、脯氨酸、丙二醛含量和过氧化物酶活性。结果表明,7种杂草对高温的耐受能力,由大到小分别为野塘蒿、小飞蓬、钻形紫菀、加拿大一枝黄花、马缨丹、一年蓬和金鸡菊,对低温的耐受能力,由大到小则分别为野塘蒿、小飞蓬、马缨丹、一年蓬、钻形紫菀、加拿大一枝黄花和金鸡菊。分析了四种生理指标变化的生态适应意义。     

温度对六种外来杂草过氧化物酶同工酶谱的影响

应用聚丙烯酰胺垂直板凝胶电泳 ,比较了加拿大一枝黄花 (Solidagocanadensis)、小飞蓬 (Conyzacanadensis)、野塘蒿 (Conyzabonarinsis)、钻形紫菀 (Astersublatus)、一年蓬 (Erigeronannuus)和马缨丹 (Lan tanacamara)等 6种外来杂草在 3 8、2 5、5°C处理 60h后的过氧化物酶同工酶谱差异 ,分析了酶谱差异与对温度适应的关系。结果表明 ,温度变化对一年蓬、小飞蓬、钻形紫菀过氧化物酶同工酶谱的影响相对较小 ,野塘蒿通过增加酶带、调整同工酶的组成来适应温度的变化 ,反映出这 4种杂草对温度变化具有较强的适应能力 ;加拿大一枝黄花表现出对高温的适应能力较弱 ,对低温适应性较强 ,马缨丹对温度变化表现出相反的适应特点。     

喜旱莲子草沿河岸带不同生境的盖度变化及形态可塑性

喜旱莲子草(Alternanthera philoxeroides)原产南美洲,是中国国家环保总局公布的9种危害最大的外来入侵植物之一。该文比较了分布于河岸带4种小生境中,喜旱莲子草和它的同属土著植物莲子草(Alternanthera sessilis)的盖度和生长特征变化,以了解影响喜旱莲子草入侵的生境和生长特征。按照距水体的距离远近,这些小生境依次为:废弃农田、沼泽、河边沙石滩及河间卵石滩。 结果表明,这4种生境在基质性质、土壤养分和生产力方面存在显著的差异。在生产力较高的生境中(如废弃地和沼泽),喜旱莲子草是优势种,但在生产力较低的生境中(即河边砾石滩及河间卵石滩)土著种莲子草的相对盖度大于喜旱莲子草。随着生境土壤养分的增加,喜旱莲子草表现出明显的形态可塑性。喜旱莲子草与觅光相关的几个形态指标,如茎的长度、节间长度和节的数目以及单叶面积都显著增加;同时,那些着生叶片的分枝也从匍匐状转变成直立生长。在生产力较高的生境中,喜旱莲子草的植冠高度和茎干密度成正相关,表明喜旱莲子草对极度密集的种群环境有很强的适应能力。这些结果说明,较高的形态可塑性和优先占据具有较高土壤养分的小生境是喜旱莲子草沿河岸带入侵的基本特征,可能也是促成其入侵的重要的内部(植物自身)和外部(生境)条件。     

10种菊科植物水提液对小麦幼苗生长的影响

用小白酒草、黄鼠草、刺儿菜、一年蓬、苍耳、苦苣菜、旋覆花、紫菀、黄花蒿、野塘蒿等10种菊科植物的水提液,对小麦进行不同浓度的皿内沙培实验,分别对小麦的根长、苗高及鲜重等三项指标进行测定的统计结果表明：10种菊科植物水提液对小麦幼苗生长的影响依种类有差异,其中旋覆花、黄花蒿、野塘蒿、紫菀对小麦表现出明显克生作用,而小白酒草、黄鼠草则表现出一定的促生作用;刺耳菜、一年蓬、苍耳对小麦幼苗生长的影响不明显。     

城市郊区外来杂草生态位特点及对生物多样性影响研究

采用样方法调查金华市郊春夏季节非农田生境的外来杂草和主要"土著性"杂草的种类和分布,分析外来杂草和其他主要杂草的生态位关系,定量分析了外来杂草对城市郊区植物多样性的影响。结果表明:(1)50个样地中共出现21种外来杂草,其中以野塘蒿、一年蓬、北美车前的生态位宽度最大,分别达到0.7819、0.6915、0.5237;(2)大致可将50种杂草分成3大类,其中21种外来杂草根据其对环境资源利用的差异又可分为4组;(3)人为干扰因素和土壤水分条件是影响外来杂草分布、危害的主要因素;(4)样地聚类群VI、I、III、II的外来杂草丰富度递增,并与物种丰富度成正比,说明外来杂草在一定程度上丰富了局部环境的物种多样性;(5)外来杂草重要值与物种丰富度呈线性显著负相关,表明金华市郊外来杂草的入侵对生物多样性有不利的影响;(6)外来杂草重要值较外来杂草丰富度更为适合衡量外来杂草对生物多样性的影响。     

南京市春季外来杂草调查及生态位研究

利用样方法调查了南京市不同生境下外来杂草的种类、盖度、密度情况,探讨了不同生境中外来杂草对杂草群落的影响,同时分析了10种主要外来杂草和本地伴生种的生态位特点.结果表明,南京市春季外来杂草有36种,在74个样点中外来杂草出现的频率达到98.65%;外来杂草的入侵对生物多样性有不利影响;外来杂草平均优势度在不同生境中大小次序为:水边>菜地>荒地>路旁>景区>田埂>草坪>果茶园>墙缝>农田>宅旁>山坡.生态位的研究结果表明:野塘蒿 Conyzabonariensis L. Cronq. 、野老鹳草 GeraniumcarolinianumL. 和阿拉伯婆婆纳 VeronicapersicaPoir. 是生态位宽度最高的外来杂草,其入侵性最强;具有较高生态位宽度的外来杂草与其它杂草的生态位重叠较大,具有相似形态特征的杂草间的生态位重叠较大.     

东苕溪江流域喜旱莲子草分布特征及其与水质的相关性研究

利用样方法对东苕溪江流域喜旱莲子草(Alternanthera philoxeroides)群落分布特征进行调查的同时在调查点周围监测水体中的总氮(TN)、总磷(TP)、化学需氧量(COD)、pH 等参数, 探讨喜旱莲子草的分布特征及其与水质的相关性。结果表明: 喜旱莲子草的重要值和盖度的变化与TN 和COD 的变化存在显著正相关性, 而水体的TP 含量对喜旱莲子草的分布无显著影响。同时, 当地人的干扰几乎无科学防治措施, 加剧了其分布扩散。     

苏南丘陵茶园秋季杂草群落多样性分析

为揭示不同生境茶园秋季杂草的物种组成、生物多样性及其危害性,于2011和2012年的10月,调查了江苏金坛不同自然环境、不同管理措施、不同种植时间茶园的秋季杂草种类、数量、高度,进而基于聚类分析以及生境特点,将茶园分成5个不同生境类群,分析了不同生境类群杂草群落的结构特征及生物多样性。结果表明:由于生境类型和管理水平导致的资源差异的影响,不同杂草群落的杂草科、属、种组成差异显著,群落结构存在明显分化,1年生与多年生杂草比例不同。类群Ⅲ为牛筋草(Eleusine indica)+小旱稗(Echinochloa crusgalli var.austro-japonensis)+马唐(Digitaria sanguinalis)杂草群落,类群Ⅳ为马唐+爵床(Rostellularia procumbens)+铁苋菜(Acalypha australis)+牛筋草+一年蓬(Erigeron annus)+小飞蓬(Conyza canadensis)+酢浆草(Oxalis corniculata)杂草群落,这2种类群的杂草群落物种丰富度、物种多样性与均匀度大,主要种较多,群落的结构复杂且稳定,对环境的变化或来自物种群落内部种群波动的缓冲作用强;类群Ⅱ为虮子草(Leptochloa panicea)+小飞蓬+地锦(Euphorbia humifusa)+一年蓬杂草群落,类群Ⅴ为麦冬(Ophiopogon japonicus)+小飞蓬+井栏边草(Pieris multifida)+叶下珠(Phyllanthus urinaria)+爵床杂草群落,这两种类群的杂草群落稳定性次之,杂草危害的严重性较低;类群Ⅰ为马唐+一年蓬+小旱稗+牛筋草+酢浆草+铁苋菜杂草群落,群落生物多样性各项参数值基本与其他类群相反,群落中优势种突出,极容易发生严重危害。     

不同水陆生境下入侵种喜旱莲子草与土著种莲子草表型变异和细胞渗透势调节能力的比较研究

喜旱莲子草(Alternanthera philoxeroides(Mart.)Griseb.)能成功入侵不同水陆生境,而其同属近缘种莲子草(A.sessilis(Linn.)DC.)适于生长在潮湿的陆地环境中。为揭示两物种生态幅差异的机理及与其入侵潜力的关系,我们在模拟不同水陆生境的同质园环境下,比较了喜旱莲子草和莲子草的形态特征、细胞渗透势变异状况和细胞内溶质物质合成相关基因(蛋氨酸合成酶基因)的表达水平。结果表明:喜旱莲子草对环境变异更敏感,表型变异幅度更大,具有更有效的渗透势调节能力;蛋氨酸合成酶基因在喜旱莲子草进入水生环境的早期阶段表现出短暂上调的特殊表达趋势。这说明有效的细胞渗透势调节机制与喜旱莲子草对不同水陆生境的广泛适应性和较强的表型可塑性能力可能有关,从而帮助其在不同生境中成功入侵。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

2018年中国植物科学若干领域重要研究进展

2018年中国植物科学继续呈现快速发展的态势, 我国科学家在国际植物科学主流学术刊物发表论文数量大幅增加, 取得了多项具有重要影响的成果。调控植物生长-代谢平衡实现可持续农业发展入选2018年度中国科学十大进展; 中国被子植物区系进化历史研究入选2018年度中国生命科学十大进展。以水稻为代表的农作物和果蔬等经济作物研究在国际上已呈现出明显的优势, 若干领域已从“追赶”状态跨越到“领跑”地位。该文对2018年中国科学家在植物科学若干领域取得的重要研究成果进行了概括性评述, 旨在全面追踪和报道当前中国植物科学领域的发展前沿和热点, 展示中国科学家所取得的杰出成就。     

2017年中国植物科学若干领域重要研究进展

2017年中国植物科学继续保持高速发展态势, 重大成果频出, 具体表现在中国植物学家在国际顶级学术期刊发表的文章数量平稳上升。中国植物科学领域的研究工作者成果精彩纷呈, 如新型广谱抗病机制的发现、水稻广谱抗病遗传基础及机制和疫霉菌诱发病害成灾机制研究等。2017年中国生命科学领域十大进展评选中, 有两项植物科学领域的研究成果入选。水稻生物学、进化与基因组学和激素生物学等领域学科发展突出。另外, 值得一提的是, 长期从事高等植物与代谢途径调控分子网络研究和水稻品种设计育种的李家洋院士的研究成果“水稻高产优质性状形成的分子机理及品种设计”荣获2017年国家自然科学一等奖。这一具有重大国际影响的开创性贡献标志着中国植物科学在该领域的国际科学前沿居于引领和卓越地位。该文对2017年中国本土科学家在植物科学若干领域取得的重要研究成果进行了系统梳理, 旨在全面追踪和报道当前中国植物科学领域发展的最新前沿动态, 与广大读者共同分享我国科学家所取得的辉煌成就。     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.     

2018年中国植物科学若干领域重要研究进展

2018年中国植物科学继续呈现快速发展的态势, 我国科学家在国际植物科学主流学术刊物发表论文数量大幅增加, 取得了多项具有重要影响的成果。调控植物生长-代谢平衡实现可持续农业发展入选2018年度中国科学十大进展; 中国被子植物区系进化历史研究入选2018年度中国生命科学十大进展。以水稻为代表的农作物和果蔬等经济作物研究在国际上已呈现出明显的优势, 若干领域已从“追赶”状态跨越到“领跑”地位。该文对2018年中国科学家在植物科学若干领域取得的重要研究成果进行了概括性评述, 旨在全面追踪和报道当前中国植物科学领域的发展前沿和热点, 展示中国科学家所取得的杰出成就。     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义.综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望.     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。     

Changes in aquatic vegetation in Rhine floodplain streams in Alsace in relation to disturbance

Abstract. Changes are described in aquatic vegetation in oligotrophic, groundwater-fed Rhine floodplain streams in Alsace (eastern France), resulting from disturbance. Disturbance factors include changes in nutrients, either permanent ones - effluent from a waste water treatment plant or trout hatcheries - or periodic ones: flooding. Regular inputs of high levels of phosphate and ammonia modified the macrophyte vegetation in these streams. The floristic composition, which was characteristic of oligotrophic waters upstream of the eutrophicated sector, changed to that of a eutrophic situation as originally found downstream. Periodic disturbance by floods which normally occur once a year, irregularly eutrophicates the small streams, causing the development of a mixture of eutrophic and oligotrophic species. Six macrophyte communities are distinguished, indicating different trophic levels. The aquatic vegetation is adapted to the variations of phosphate and ammonia levels. Hence, aquatic macrophytes can be used as bio-indicators of fluctuations in water nutrient levels in relation to the type of disturbance.     

Apoptosis in experimental myocardial infarction in situ and in the perfused heart in vitro

We report the appearance of apoptotic cells in experimental myocardial infarction (rabbit heart) in in situ and in vitro preparations. Apoptosis was recognized by intravital staining with Hoechst 33342 (Ho342), by nick-end labeling (TUNEL) and by DNA laddering. A steady rise in the relative number of apoptotic cardiomyocytes (apoptotic index) was noted in in situ preparations. Apoptosis was first noted 6 h after the onset of ischemia with its highest value occurring after 72 h. Apoptotic nuclei were absent in remote areas of the left and right ventricles. Apoptotic nuclei within the infarcted area showed diminished intensity of Ho342 fluorescence. Three days after ischemia, a border zone adjacent to the infarcted area consisting of apoptotic macrophages was recognized. A novel finding was the appearance of apoptotic cardiomyocytes in the isolated perfused ischemic heart. Occurring as early as 50 min after the onset of ischemia, a high apoptotic index was present adjacent to the ligature placed around the coronary artery. This observation provides the opportunity to selectively examine factors leading to apoptosis in the ischemic heart under controlled experimental conditions.     

Morphine-potentiated platelet aggregation in in vitro and platelet plug formation in in vivo experiments

The detailed mechanisms underlying morphine-signaling pathways in platelets remain obscure. Therefore, we systematically examined the influence of morphine on washed human platelets. In this study, washed human platelet suspensions were used for in vitro studies. Furthermore, platelet thrombus formation induced by irradiation of mesenteric venules with filtered light in mice pretreated with fluorescein sodium was used for an in vivo thrombotic study. Morphine concentration dependently (0.6, 1, and 5 microM) potentiated platelet aggregation and the ATP release reaction stimulated by agonists (i.e., collagen and U46619) in washed human platelets. Yohimbine (0.1 microM), a specific alpha(2)-adrenoceptor antagonist, markedly abolished the potentiation of morphine in platelet aggregation stimulated by agonists. Morphine also potentiated phosphoinositide breakdown and intracellular Ca(2+) mobilization in human platelets stimulated by collagen (1 microg/ml). Moreover, morphine (0.6-5 microM) markedly inhibited prostaglandin E(1) (10 microM)-induced cyclic AMP formation in human platelets, while yohimbine (0.1 microM) significantly reversed the inhibition of cyclic AMP by morphine (0.6 and 1 microM) in this study. The thrombin-evoked increase in pH(i) was markedly potentiated in the presence of morphine (1 and 5 microM). Morphine (2 and 5 mg/g) significantly shortened the time require to induce platelet plug formation in mesenteric venules. We concluded that morphine may exert its potentiation in platelet aggregation by binding to alpha(2)-adrenoceptors in human platelets, with a resulting inhibition of adenylate cyclase, thereby reducing intracellular cyclic AMP formation followed by increased activation of phospholipase C and the Na(+)/H(+) exchanger. This leads to increased intracellular Ca(2+) mobilization, and finally potentiation of platelet aggregation and of the ATP release reaction.