不同林龄马尾松人工林林下植物多样性与土壤理化性质

为了解长江上游低山丘陵区不同林龄的马尾松(Pinus massoniana)人工林植物物种多样性与土壤特性的变化特征及其联系,选取不同林龄的马尾松人工林作为研究对象,对林下植物多样性和土壤理化性质进行研究。结果表明:(1)3年生马尾松林下喜光植物较多,随林龄增加人工林郁闭度增大,耐阴植物增多。(2)林下物种丰富度指数中龄林最大,成熟林略有下降但明显高于幼龄林。草本层、灌木层的Simpson指数和Shannon指数随林龄增加均呈现早期波动、中期下降、后期增加的变化趋势。(3)随林龄增加,土壤各理化指标的变化不尽相同,但到成熟林时期,土壤有机质、全氮、全磷含量均有所升高,说明马尾松林到成熟林阶段其土壤肥力状况得到一定的提升。(4)群落演替过程中物种多样性变化与土壤因子存在一定相关性,土壤pH、土壤含水量、全磷与植物多样性的关系最为密切。土壤理化性质影响着物种更新和演替进程,同时林下植物群落的演替导致土壤水分和养分发生变化,使得土壤基质的稳定性提高,为更多物种的生存、定居、生长发育提供良好的条件。     

巴丹吉林沙漠南缘植被物种多样性及其与土壤特性的关系

通过对巴丹吉林沙漠南缘地区植被的野外调查,探讨了植被物种组成与物种多样性对样地沿距沙漠中心的距离变化的响应,以及物种多样性与土壤因子间的关系。结果表明:(1)研究区主要物种共计10科18属20种,植物种类以沙漠旱生植物为主,样地的植被群落类型都是灌木与草本植物群落。(2)随着样地向沙漠外缘的延伸,植物种类和数量逐渐增多,群落结构更加复杂化和多样化;样地Shannon-Wiener指数和Simpson指数呈上升趋势,优势度指数逐渐下降;灌木层与样地的α多样性指数变化趋势一致,草本层变化幅度较小;β多样性指数中BrayCurtis指数呈下降趋势,说明植物群落之间的物种替换速率降低。(3)物种多样性指数与土壤因子的相关关系及逐步回归分析表明土壤有机质和土壤全氮含量对植被的影响显著,土壤表层20~40cm中的土壤速效磷与样地物种多样性和草本层物种多样性之间具有显著相关关系。     

昆阳磷矿不同植被恢复模式对土壤理化性质和细菌群落的影响

土壤微生物在物质循环过程中具有重要作用且对环境变化敏感,是衡量土壤质量的重要指标．在恢复生态学研究中具有重要意义。为探究不同植被恢复模式对土壤理化性质和细菌群落的影响以及土壤细菌群落差异的原因,本研究以云南省昆阳磷矿为研究对象,运用PCR-DGGE技术和理化指标测定分析了三种植被恢复模式（芒草丛、旱冬瓜藏柏麻栎混交林、藏柏旱冬瓜混交林）下土壤细菌群落多样性、物种组成及土壤理化性质。结果表明：（1）植被恢复有助于改善土壤养分,不同植被恢复模式下土壤理化性质以及细菌群落多样性和物种组成均存在差异。（2）土壤细菌多样性与植被恢复模式之间具有显著相关性,但与土壤理化指标均无显著相关性。（3）土壤细菌群落物种组成与土壤碱解氮含量以及植被恢复模式间具有极显著相关性,与其他土壤理化指标间无显著相关性。本研究表明磷矿区不同植被恢复模式下土壤理化性质和细菌群落均具有差异,土壤细菌群落多样性差异的主要原因为植被恢复模式不同,物种组成差异的主要原因为土壤碱解氮含量不同,其次为植被恢复模式不同。     

单户与联户经营对高寒草甸土壤理化性质与植物多样性的影响

在甘南高寒草甸单户经营草场与联户经营草场进行野外群落学调查,分析其物种多样性和功能多样性的变化,以揭示不同经营方式下土壤理化性质对植物多样性的影响机制。结果显示：（1）联户草场内植物群落的Margalef指数、Simpson指数、Shannon-Winener指数较大,而Pielou指数在不同放牧经营方式下的差异并不显著。（2）不同经营方式下,土壤含水量、土壤全氮、土壤全磷和土壤有机碳质量分数表现为联户大于单户的趋势且差异显著（P<0.05）;单户草场土壤电导率与土壤pH大于联户草场;随着土层的加深土壤含水量、土壤全氮质量分数、土壤全磷质量分数、土壤有机碳质量分数和土壤电导率增加,而土壤pH在土层之间的差异并不显著。（3）联户经营方式下的功能丰富度、功能均匀度与功能离散度显著大于单户草场（P<0.05）。（4）相关性分析表明,植物群落物种多样性和功能多样性与土壤含水量、土壤全氮质量分数和土壤全磷质量分数存在正相关关系,土壤电导率和土壤pH与植物群落物种多样性和功能多样性存在负相关关系。冗余分析表明,联户经营方式下土壤理化性质对植物多样性的影响更显著,且0＜h≤10 cm土层土壤理化性质与植物多样性的相关性更高。单户经营方式下,土壤全氮和土壤有机碳是植物多样性的显著影响因子,联户经营方式下,土壤全氮和土壤全磷是植物多样性的显著影响因子。     

长白山不同演替阶段针阔混交林群落物种多样性及其影响因子

基于长白山3个5.2hm²针阔混交林永久监测样地的野外调查数据,以胸径(DBH)≥1cm的乔木树种为对象,运用R4.0.3软件计算物种多样性指数以及进行物种多样性相关性分析和多元回归分析,以探讨生物和非生物因素对不同演替阶段针阔混交林物种多样性的影响。结果表明：(1)3个典型针阔混交林的4个物种多样性指数均随演替的正向进行而下降,其中物种丰富度、Shannon-Wiener指数和Simpson指数在3个演替阶段存在显著性差异,而Pielou均匀度指数在次生杨桦林与次生针阔混交林阶段差异不显著。(2)胸径结构变量是影响物种多样性变化的主要驱动因子,随着演替的进行,林分密度对物种多样性产生的影响越来越大。(3)所有土壤因子在针阔混交林阶段对物种多样性指数均表现出显著的影响,而在次生杨桦林只有土壤全氮与物种多样性指数存在显著相关关系,土壤全磷在原始椴树红松林阶段是影响物种多样性的主要因素。综上,研究认为在各演替阶段,生物和非生物因素均影响着森林群落的物种多样性,胸径结构和林分密度是影响群落物种多样性的主要因素,林分中的土壤因子受到不同群落特征的影响产生不同变化,从而对群落的物种多样性产生影响也有所不同。     

陕北黄土丘陵区撂荒草地群落生物量及植被土壤养分效应

为了明确植被演替过程中植被与土壤的互动效应，为植被恢复提供依据。根据陕北黄土丘陵区36块不同年限（时间尺度为2—45a）的撂荒样地地上生物量、土壤养分和水分的测定结果，及4块典型撂荒群落样地地上／地下生物量，7种撂荒群落主要植物生长特性的测定，分析了撂荒演替过程中群落生物量与土壤养分的变化过程、趋势及其相互关系，进而探讨了撂荒演替过程中群落生物量对土壤养分的作用效应，并利用多元回归和通径分析法分析了土壤养分对群落生物量的作用。结果表明：（1）除速效磷外，撂荒演替过程中群落地上生物量和土壤有机质、全氮、全磷、全钾、NO3-N、NH4-N和速效钾都呈先减少后增加的趋势，步调基本一致。（2）从撂荒年限与土壤养分的相关性来看，0—20cm土壤有机质含量、速效磷含量和0—20、20—40cm土壤层NO3-N含量与撂荒年限相关显著，说明演替过程中有机质、速效磷和NO3-N有较为明显的植被土壤效应，而其它土壤养分与撂荒年限相关不显著，不能排除演替初始条件和植物暂时固定的影响；从群落生物量与土壤养分的相关性来看，群落生物量对土壤有机质、全氮、磷、钾、NO3-N、速效钾和速效磷含量具有正效应，而对NH4-N具有负效应，但都不显著。（3）通径分析说明撂荒年限、土壤全氮、全钾、速效钾和土壤水分变异量对生物量表现为正的直接作用，其中以撂荒年限和土壤水分波动量作用较大，土壤养分对群落地上生物量的作用以土壤全氮最大，全钾和速效钾影响较小；演替过程中群落地上生物量的变化主要是由于植被盖度和群落组成种的生态学特性造成的（撂荒年限较大的直接作用），其次是由于撂荒演替过程中土壤水分的波动造成的（撂荒年限通过土壤水分的间接负作用）。（4）随着土层深度的加深植物根系生物量呈幂函数递减过程，演替后期群落根冠比有增加的趋势，演替后期序列种根冠比和根长也有增加的趋势，这些在一定程度上会影响到生物量积累和有机质分解等，进而会影响到植被土壤效应。     

高原湿地沼泽化草甸土壤真菌与理化性质的关系

以高原湿地纳帕海沼泽化草甸为研究对象, 采用稀释培养结合形态鉴定比较分析0—20 cm、20—40 cm土层的土壤真菌多样性及群落结构组成, 以及土壤理化性质对土壤真菌多样性及群落结构组成的影响。结果表明: 0—20 cm和20—40 cm土层中的真菌数量、Shannon-Wiener多样性指数(H')、均匀度指数(JSW)和丰富度指数(DMA)均表现为0—20 cm土层> 20—40 cm土层; 分别分离得到土壤真菌12属和10属, 其中木霉属、青霉属、腐霉属、曲霉属同为沼泽化草甸两个土层的优势类群, 表现出较高的相似性, 同时20—40 cm未发现枝孢菌属和壳囊孢属, 又表现出一定的差异性。经RDA冗余分析, 土壤有机质、全氮、速效钾、速效磷、pH、容重和自然含水率可能是影响沼泽化草甸土壤真菌群落结构组成的主要因子。     

海南琼北地区不同植被类型物种多样性与土壤肥力的关系

研究海南岛琼化弃荒坡耕地不同植被类型植物多样性与土壤肥力演变的相互关系的结果表明,不同植被类型的α－多样性指数的增加和土壤肥力（有机质含量和氮含量）的增加正相关明显,β－多样性指数在草本植物群落与灌丛的过渡区变化较强烈,而土壤有机质含量变化较大的地方则是在疏灌丛与密灌丛之间,表现出在植被恢复的同时,土壤有机质含量也会有所增加,但后者一般稍滞后一段时间。在对土壤肥力与植被性状的关系进行多元回归分析后发现,土壤有机质含量主要与演替后期植物种类的发展有关;而土壤全氮则与群落覆盖度,木本植物种数和演替后期植物种数等多个因素有关;全磷稍与物种多样性有关。土壤全钾和pH变化比较复杂,与植物组成性状的关系没有选择项。     

新疆塔里木河下游土壤特性及其对物种多样性的影响

结合塔河下游大西海子至台特玛湖区段的8个地下水监测断面、31个土壤剖面的217个土样分析数据,利用非参数检验、单因素方差分析和灰色关联方法,分析了塔河下游土壤特性及其对物种多样性变化的影响.研究结果表明,塔河下游土壤除全磷外,有机质等指标存在垂直分布差异,出现显著差异的土层深度为50cm.塔河下游上段的土壤养分含量相对较高,下段较低;物种多样性指数自上段至下段的下降趋势与有机质等的变化相同,而植物群落退化则表现为从复合群落到单一群落的演变趋势,即从乔(胡杨为主)、灌(柽柳为主)、草复合群落演变到单一的柽柳灌丛群落.灰色关联分析表明塔河下游上层(0～50cm)土壤有机质、全氮、全磷、全钾含量与物种多样性的相关性较高.塔河下游土壤有机质、全氮、全磷、全钾等在一定程度上对物种多样性变化有一定影响.     

喀斯特植被演替过程土壤丛枝菌根真菌(AMF)多样性

喀斯特生态系统维持了丰富的微生物多样性,丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)结构和组成会随喀斯特植被演替而改变。以贵州贵阳花溪、毕节织金和关岭花江典型喀斯特区域按时空替代法采集了乔木林、灌木林和草本群落样地土壤,采用Illumina HiSeq分子测序技术,通过OTU聚类分析、物种注释及数据库比对,探索了喀斯特不同演替阶段土壤AMF物种多样性。结果表明:(1)喀斯特生境土壤获得球囊菌门Glomeromycota OTU为275个,分属于4目8科13属19种,属水平上AMF丰度表明根内根孢囊霉属Rhizophagus为优势属,花江拥有最高AMF丰富度,缩隔球囊霉Septoglomus constrictum、根内根孢囊霉Rhizophagus intraradices、Claroideoglomus sp. MIB8381和稀有内养囊霉Entrophospora infrequens均分布于各样地的不同植被演替阶段,为常见种。(2)AM真菌多样性Shannon指数与Simpson指数在不同演替阶段表现为花溪:乔木≈灌木草本(P0.05)、花江:灌木≈草本乔木(P0.05)、织金:乔木灌木草本,但差异不显著,Chao1和Abundance-based coverag estimator(ACE)指数表现为花江灌木≈草地乔木(P0.05)。(3)Spearman相关性分析表明土壤全磷与AMF ACE指数显著负相关,且与Chao1指数极显著负相关;速效磷与Shannon和Simpson指数显著负相关。(4)典范对应分析(Canonical Correlation Analysis,CCA)表明土壤全氮、速效氮、有机质、全磷和速效钾与AMF群落分布有显著相关性。结果表明喀斯特植被演替过程中土壤丛枝菌根真菌多样性随着演替进行或升高或降低,无一致变化规律,并与土壤理化性质关系密切,其中以磷的影响最大。     

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.     

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。     

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。     

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。     

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.     

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.     

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.