Estudo fitoquímico e biológico das folhas de Banisteriopsis argyrophylla (A. Juss.) B. Gates (Malpighiaceae)

With the increasing fungi resistance compared with existing drugs on the market and the side effects reported by some compounds with antioxidant properties and enzymatic inhibitors, in particular against α-amylase and α-glucosidase, the discovery of new compounds with biological potential, becomes a need. In this context, natural products can be an important source for the discovery of new active molecular architectures. Then, this study aimed to evaluate the antioxidant activity, the enzymatic inhibitory activity of α-amylase and α-glucosidase, the antifungal and cytotoxic activities of ethanolic extract (EE) the leaves of Banisteriopsis argyrophylla (Malpighiaceae) and their fractions, obtained by liquid-liquid extraction using solvents of increasing polarity. The antioxidant activity was evaluated by the free radical DPPH scavenging method (2,2-diphenyl-1-picrylhydrazyl) and the ethyl acetate fractions (FAE) and n-butanol (FB) were the most active, confirmed by the peak current and the oxidation potential obtained by differential pulse voltammetry (DPV). The inhibitory activity of the α-amylase and α-glucosidase was analyzed considering the reactions between substrates α-(2-chloro-4-nitrophenyl)-β-1,4-galactopiranosilmaltoside (Gal-α-G2-CNP) and 4-nitrophenyl-α-D-glucopyranoside (p-NPG), respectively. Initially, it was found that the EE showed considerable activity against α-amylase (EC50 = 2.89±0.1 μg m L–1) compared to the acarbose used as positive control (EC50 = 0.08±0.1 μg mL–1) and that did not showed promising activity against the α-glucosidase. After this observation we evaluated the inhibitory activity of α-amylase fractions, with FAE (EC50 = 2.33±0.1 μg mL–1) and FB (EC50 = 2.57 ± 0.1 μg mL–1) showing the best inhibitions. The antifungal activity was evaluated against Candida species, and the FAE had better antifungal potential (MIC's between 93.75 and 11.72 μg mL–1) compared with amphotericin as positive standard (MIC = 1.00 and 2.00 μg L–1 for C. parapsilosis and C. krusei used as controls, respectively). The EE (CC50 = 360.00 ± 12 μg mL–1) and fractions (CC50's> 270.00 μg mL–1) were considerably less toxic to Vero cells than the cisplatin used as positive control (CC50 = 7.01 ± 0 6 μg mL–1). The FAE showed the best results for the activities studied, this fraction was submitted to ultra performance liquid chromatography coupled with mass spectrometry (UPLC-MS)), and the following flavonoids have been identified: (±)-catechin, quercetin-3-O-β-D-Glc/ quercetin-3-O-β-D-Gal, quercetin-3-O-β-L-Ara, quercetin-3-O-β-D-Xyl, quercetin-3-O-α-L-Rha, kaempferol-3-O-α-L-Rha, quercetin-3-O-(2''-galoil)-α-L-Rha, quercetin-3-O-(3''-galoil)-α-L-Rha and kaempferol-3-O-(3''-galoil)-α-L-Rha,. FAE was submitted to column chromatography using C18 phase, and (±)-catechin was isolated (FAE-A1, 73 mg) and three fractions consisting of a mixture of flavonoids were obtained (FAE-A2, FAE-A3 and FAE-A4). These compounds were identified by thin layer chromatography (TLC) and (–)-ESI-MS. The (±)-catechin fraction showed an MIC = 2.83 μg ml–1 in assay using C. glabrata, with amphotericin as positive control. The fractions FAE-A2, FAE-A3, FAE-A4, showed less antifungal potential in tested concentrations. The identified flavonoids are described in the literature, regarding their antioxidant capacity and (±)-catechin, quercetin-3-O-Rha and kaempferol-3-O-Rha are described as α-amylase inhibitors. Thus, B. argyrophylla is an important species that produces compounds with antioxidant potential that can be related to the traditional use as anti-inflammatory and also has antifungal compounds and inhibitors of α-amylase. Therefore, these leaves are promising resources for the production of new drugs.

Pericarp structure in Banisteriopsis CBRob. and Diplopterys A.Juss. (Malpighiaceae): new data supporting generic segregation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Morfoanatomia e ontogênese das sementes de espécies de Banisteriopsis C.B. Robinson e Diplopterys A. Juss. (Malpighiaceae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influência da variação sazonal da temperatura e umidade do solo na germinação de sementes de espécies do cerrado: Xylopia aromatica (Lam.) Mart. (Annonaceae), Banisteriopsis variabilis B. Gates (malpighiaceae) e Vochysia tucanorum Mart. (Vochysiaceace)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Prospecção química e avaliação biológica de Banisteriopsis laevifolia (Malpighiaceae)

The Banisteriopsis genus is widespread in traditional medicine. This work aims to contribute with information about the chemical composition and on the evaluation of the biological activity of the essential oil, the ethanol extract of the leaves and partitions of the Banisteriopsis laevifolia. The phytochemical screeningtest of ethanol extract and partitions of leaves indicated the presence of flavonoids, terpenoids, saponins, phenols and steroids compounds. Nitrogenous compounds, characteristic of some species of this family, were not detected. Flavonoids were the predominant metabolite, with the highest concentrations on the partitions ethyl acetate and n-butanol. The antibacterial activity, antifungal and cytotoxicity of the essetial oil, ethanol extract and partitions were assyed by microdilution broth method (MBM), where the minimum inhibitory concentrations (MIC) were calculated. The ethanol extract and partitions did not inhibit growth against to Gram positive bacteria tested, with MIC less than 400 mg L-1. For the Gram negative bacteria tested, the hexane and hydroethanol partitios were more effective against F. nucleatum bacteria (MIC 100 ug mL-1). The ethanol extract showed antifungal activity with MIC of 31.2 mg L-1. Ethyl acetate and n-butanol partitions showed MIC 187.5 mg L-1 and 93.7 mg L-1, respectively, arousing interest for isolation studies. The antioxidant activity was evaluated by the DPPH free radical method. The ethanolic extract, ethyl acetate and n-butanol partitions were active, since they showed EC50 values (4.53 ug mL-1, 4.07 and 8.39 ug mL-1, respectively), values equivalent to the BHT (7.3 mg L-1). The analysis by HPLC-MS/MS of the most active fractions (ethyl acetate and n-butanol) identified phenolic compounds (flavonols and phenolic acids) which exert recognized biological activity. The GC-MS analysis of the essential oils from leaves collected in two periods studied (dry and wet), showed a small variation in the number of compounds. The major classes identified for the oil collected in the dry period were aliphatic alcohols (23,4%), terpenoids (18.7%), sterols (10.4%) and long-chain alkanes (9.2%) compounds. Terpenoids (26.8%) were the major class for the rain season. The major compounds (3Z) -hexenol, phytol and untriacontano are present in the two seasons but in different amounts (19.4%, 9.8% and 7.5% during the dry season, and 17.0 %, 14.9% and 15.3% in the rainy season, respectively). The essential oil from rainy season was not effective against to the oral bacteria Gram positive and Gram negative tested. However, showed significant antifungal activity with MIC 1000 mg L-1 against Candidas. Thus, the promising results with respect to biological assays of ethanolic extract and partitions from B. laevifolia contributed to the chemical and biological knowledge of the species B. laevifolia.

银杉的遗传多样性及系统位置的研究一兼论松科的分子系统学

银杉属Cathaya是我国著名植物学家陈焕镛和匡可任建立的松科单型属，该属是否成立及该属在松科中的系统位置至今仍众说不一。银杉Cathazyaargyro phylla是银杉属的唯一幸存种，被誉为第三纪的活化石，并被列为我国一级保护的濒危植物，也是世界植物红皮书所列少数几种濒危裸子植物之一，保护区虽已设立数个，但该物种的濒危原因仍为未解之谜。本文针对上述问题开展了松科植物的分子系统学研究，探讨了银杉属的系统位置及松科的属间关系，并通过遗传多样性的研究探讨了银杉的濒危机制及保护策略。 1．松科的分子系统学研究 为选取合适的分子标记，本文先探讨了ITS-1在松科等裸子植物中的系统学价值。对1 6种裸子植物（其中含松科10属12种）的ITS-1的扩增结果如下：ITS-1在裸子植物属闻存在极大的长度变异(约600-2600bp)，因而不适用于属级以上的系统学研究;在同属种中，ITs-1的长度虽较一致，但与被子植物的ITS-1相比，裸子植物的ITS-1太长(如在松属中超过2600bp)，难以进行大规模研究。银杉属ITS-1的扩增产物中，一个片段的长度与松属ITS-1的长度相当，另一个片段的长度与云杉属ITS-l的长度相当，这三属间的关系值得进一步研究。此外，在松科植物ITS-1的研究中必须注意真菌“污染”这一问题。 由于ITS不适用于裸子植物属间关系的研究，因而本文运用rbcL-accD基因片段及trnK基因的PCR-RFLP分析探讨银杉属的系统位置及松科的属间关系。rbcL和trnK虽然都是叶绿体基因，但位于trnK内含子区的natK基因与rbcL基因在所受的选择压及进化速率上相差甚远，通过这两个基因研究结果的比较有助于评价系统树的可靠性。此外，考虑到松科的10个属中有9个属的rbcL基因序列已被测定，我们补测了银杉属的rbcL基因序列，进而对松科10个属的rbcL基因序列进行了全面分析。PCR -RFLP分析及rbcL基因的序列分析结果如下： A. PCR扩增的松科rbcL-accD基因片段均长约2550bp，属间没有明显的长度变异，1 8种限制性内切酶的单酶切及7种组合双酶切共获得86个酶切位点，其中54个为变异位点。PAUP和MEGA软件分析均表明：银杉属、松属、黄杉属和落叶松属构成一个单系群，且银杉属与松属的关系似乎近于它与另外二属的关系，但这一结果来得到bootstrap分析的较强支持;黄杉属近缘于落叶松属;冷杉属近缘于油杉属。 B．PCR扩增出的松科trnK基因均长约2557bp，在属间也没有明显的长度变异。16种限制性内切酶的单酶切及7种组合双酶切共获得92个酶切位点，其中68个为变异位点。变异位点中的35个具有系统发育信息，其中28个位于matK基因上。分布于整个trnK基因上的informative位点和仅分布于matK基因上的informative位点分别用于PAUP(version 3.1.1)分析，且PAUP分析中分别用Wagner简约法和Dollo筒约法构建系统树。总体看来，Wager简约树和Dono简约树的结构基本一致（Cedrus的位置除外）：Abies、Keteleeria、Tsuga和Pseudolarix分为一支，且这一支在所有的简约树中均得到分辨;Pseudotsuga近缘于Larix,而Abkes相对近缘于Keteleeria; Cathaya与Ables-Keteleeria-Pseudolarix-Tsuga这一支的关系较远，它与松科的其它属聚在一起，但b∞tstrap分析也不支持它与任何一个属有很近的关 系，说明Cathaya是比较孤立的一个属。Cedrus的位置较特殊，在Wagner简约树中它位于松属以外的其它8个属的基部（因松属为外类群），而在Dollo筒约树中它位于Al}ies-Kete~eer uz-Pseudo/zr/x- Tsuga达一支的基部，并且它与这一支的关系得到了bootstrap分析的较强支持。 C．银杉的rbeL基因长1425bp，其序列与松科其它9个属的rbcL基因序列均有较大差异，从遗传距离(Mega软件中的P-distance)上看，银杉属作为一个属是无可非议的。PAUp和Mega软件分析均表现：Abies、Keteleeria、Pseudolter和Tsuga分为一支，且Cathaya与这一支的关系较远;Pseuaiotsuga近缘于Larix,且这二属间的关系得到了bootstrap分析的强烈支持;Abies近缘于Keteleeria，Pseudolarix近缘于Tsuga，且这两支也得到了bootstrap分析的较强支持;Cathaya与Pinus聚为一支，但支持强度不高。Cetirus的位置与trnK基因的PCR-RFLP分析结果极为相似。 根据rbcL-accD基因片段及trnK基因的PCR-RFLP分析以及rbcL基因的序列分析可以得出如下结论：<1> Cathaya作为一个属不仅是成立的，而且是一个较为孤立的属，将它置于其它任何属内都是不正确的，该属与Abies-Keteleer ia-Pseudolarx-Tsuga这一支的关系较远，相对而言Cathaya与Pinus的关系可能稍近一些。<2>松科主要分为两大支：一支含Abies、KeteZeera、Pseudolarx和Tsuga，该支中Abies近缘于KetelaeriaPseudolarix近缘于Tsuga;另一支含Pseudotsuga、Larix、Cathaya、Pinus和Picete，该支中Pseudotsuga明显近缘于Larix;Cedrus可能更近于Abies-Keteleeria-Pseudolarix-Tsuga这一支。 2．银杉的遗传多样性研究 本研究运用随机扩增多态DNA(RAPD)方法对银杉的1 1 3个个体（分别采自现存全部4个居群：金佛山、花坪、大瑶山和八西山)进行了遗传多样性检测。21个1O-mer的寡核苷酸引物共检测11个位点，其中42个位点是多态的，占37%，这一多态位点百分率仅为裸子植物多态位点百分率平均值的一半左右，说明银杉的遗传多样性水平很低。对多态位点的分析发现银杉屠群内发生了十分严重的遗传漂变，因而导致屠群间的强烈分化。AMOVA分析表明：银杉的遗传变异中，34.7%的变异存在于居群闻，这一数值是裸子植物GST平均值(6。8%)的5倍多;在金佛山屠群中，17%的遗传变异存在于亚居群间，这一数值也是裸子植物GsT平均值的两倍多。银杉的这一居群遗传结构与其它裸子植物的居群遗传结构截然不同。此外，我们提出了度量遗传多样性水平的分化指数概念及其计算方法，并发现遗传多样性水平的高低与生境的复杂程度有一定的相关性。 银杉的遗传多样性水平很低，其适应幅必然很窄，且由于严重的遗传漂变导致居群间的强烈分化，使基因流受阻，进而产生严重的近交，近交又使银杉的适应能力进一步下降，并使极为有限的遗传多样性进一步丧失，这种恶性循环会导致银杉濒危程度的加剧，甚至绝灭。 鉴于银杉独特的居群遗传结构，即有相当大一部分遗传变异存在于居群之间，取样保护时，不仅要在每个居群中取足够多的个体，而且要在尽可能多的居群中取样。就原地保护而言，由于每个居群和亚居群都有独特的基因型，因而都具有保护价值。另外，人工加强居群间的基因流（如人工授粉）对提高银杉各居群的适应能力肯定是有益的。

银杉的分子谱系地理学研究

银杉（Cathaya argyrophylla）是中国特有的濒危裸子植物，孤立分布于我国亚热带山地。虽然以往等位酶和RAPD标记的研究表明，银杉群体的遗传多样性水平很低而群体间的遗传分化很高，但迄今对该种群体的动态变化以及物种的进化历史仍缺乏了解，包括影响群体遗传结构的因素以及物种可能的避难所等，对如何有效地保护和恢复银杉群体仍缺乏科学依据。本文根据8个核基因片段和2个线粒体片段的序列数据，运用群体遗传学和谱系地理学方法，探讨了银杉在DNA水平上的多样性和群体的动态历史，探讨了影响银杉特殊的群体遗传结构的各种因素，并推测了银杉第四纪冰期的避难所，对银杉花粉活力及其变异进行检测。在此基础上，提出了保护和恢复银杉群体的具体策略和措施。主要研究结果如下： 　　1. 核甘酸多态性和群体遗传结构 　　从101个核基因片段中筛选了8个适用于银杉的片段，对来自四个地区15个群体共86个个体的胚乳总DNA进行了扩增和测序。8个核基因座位的平均核苷酸多态性（θs＝0.0022，πs＝0.0027）显著低于其它松杉植物遗传多态性的多座位估计值。四个地区中，大瑶山（DY）的多态性最高（θs＝0.0026，πs＝0.0027），八面山（BM）最低（θs＝0.0014，πs＝0.0018），大娄山（DL）和越城岭（YC）介于二者之间。大多数座位内的多态位点间紧密连锁，座位间的连锁只在八面山地区检测到。AMOVA分析表明显著性的多态性比例存在于地区间（20.05％）和地区内群体间（9.37％）。FST分析也显示群体间（FST＝0.294）和地区间（FST =0.131-0.319）存在显著的遗传分化。推测伴随着瓶颈效应而出现的遗传漂变及其有限的基因流（Nm=1.2）是导致银杉群体低水平多态性和群体间强烈分化的主要原因。 　　2．谱系地理学分析 　　利用2个线粒体片段（nad1和nad4）序列以及高变异量的核2009片段序列对银杉的谱系地理进行了探讨。2个线粒体片段的多态位点组合成3种单倍型，将银杉分成大娄山（DL）、八面山（BM）以及越城岭（YC）和大瑶山（DY）3个地区，地区间的单倍型完全不同（GST=1.0），结合核基因呈现的群体遗传结构，推测现存银杉群体至少来源于4个冰期避难所，相当于银杉现存的4个相互隔离的地区。2009座位上12个变异位点组合成8种单倍型，位于单倍型谱系内部节点的4种祖先单倍型分布广泛、出现频率最高，其它7个核基因座位具有类似谱系结构。遗传距离和地理距离没有相关性，NST (0.138)与GST (0.134)没有显著性差异，说明现存的银杉群体是相对较近的时间内片断化的产物。2009片段分离位点的失配分布（mismatch distribution）呈双峰和多峰，表明银杉群体没有经历近期的扩张，与古生物学研究证据相吻合。 　　3. 银杉的基因杂合性和花粉生命力 　　利用2009和cad两个核基因片段，采用多胚乳序列法得到总的杂合体比率为64％（2009）和60％（cad），说明银杉群体中存在高比例的杂合体。大娄山地区的杂合体比率是八面山地区的2倍。银杉杂合体比率的高低可能与其遗传多态性有关，也可能是自然选择的结果。采用TTC染色法对银杉的花粉生命力进行了测定，在干燥低温条件下银杉花粉的活力很稳定，保存一年后有活力的花粉数仍高达80％以上。通过对来自两个地区（DY和YC）7个群体共16个银杉个体花粉活力的测定发现，银杉有活力花粉比例高达93.3％，与其它裸子植物相当。花粉活力在地区间和群体间存在显著差异，花坪地区（95.2%）的花粉活力高于大瑶山（91.3%）。花粉活力在群体内个体间差异不显著。 　　4．银杉的进化历史及其保护 　　银杉的低水平的遗传多样性和独特的群体遗传结构对我们推测其冰川期避难所提供了重要依据。本研究在银杉4个孤立分布区发现了彼此不重叠的线粒体单倍型，同时核基因表现出了4个地理群，说明随着第四纪冰期气候的波动和银杉分布范围的片段化，原来广布的群体逐步萎缩，最后被保留在位于西部大娄山（DL），东部八面山(BM)，中南部越城岭(YC)和南部大瑶山(DY) 4个相互隔离的避难所。银杉独特的群体结构和动态历史对进一步制定相应的保护措施具有重要参考价值。由于遗传多态性很低，群体又小，几乎所有现存的银杉群体都面临由于随机事件导致的物种灭绝。更严重的是，当前该物种的适生环境不断恶化和片段化，以及异常低的生殖和存活率导致银杉与其它物种竞争能力很低。因此，除目前采取的原地保护策略外，迁地保护应给予优先考虑。此外，采用传统的控制授粉策略（在遗传上有显著差异的群体间开展人工杂交）是丰富其遗传多态性、恢复衰退群体的可行措施之一。

银山种群生态学研究

银杉(Cathaya argyrophylla)是我国特有的珍贵植物，被认为处于濒危状态。本文结合前人的研究，通过大量的野外调查，弄清了银杉的种质资源现状，分析银杉的群落特征，在此基础上重点研究了银杉种群的主要特征。 研究表明，现存银杉间断分布于我国亚热带山地，形成4个集结地，资源总量（株高大于1米者）不占4000棵。现有银杉群落处于演替的早、中期阶段，到演替后期，银杉将被组成地带性植被的优势阔叶树种取代。 银杉种群的空间分布格局与银杉的生物学特性及微环境有关。在老龄种群内，容易产生林窗，银杉在林窗形成异龄群聚，以寻求充足的光照和营养支持，种群多表现为集群分布;在群落内微环境异质性较明显时，也导致集群分布。在各种银杉群落中，就银杉种群而言，光因子可能是影响其分布格局的主导因子。银杉种群集群分布的格局规模虽在和群落种群间有明显差异，但大多在面积小于16平方米的较小尺度下发生。 银杉各群落类型中银杉种群年龄化加剧的现象，有些种群在某些龄组出现断层。从年龄结构看，有些银杉种群处于被阔叶树种更替的境地。 林窗干扰对银杉种群的更新意义重大，在林窗内和非林窗银杉群落内，银杉种群的重要值均为最大;银杉幼树在林窗内的高生长量普遍大于荫蔽的林冠下，这些充分说明银杉是典型的林窗更新方式。 银杉结实有明显的大小年之分，一般在2-3个小年之后为1-2个大年，母树结实量不与树龄成正相关，在植株间差别很大。每个球果出种量平均为4.267粒，无种子的球果占比重达12.2%。饱满种子的平均重量仅为0.0197克，远远低于乔木树种种子的平均水平。林地内自然善状况下播种，种子发芽率仅为21%，松土后播种可使发芽率加倍。种子宜于湿沙贮藏，干藏导致种子发芽率大幅度下降。松鼠是长期危害球果的主要动物，其危害率可达15%。 对银杉生长规律的研究发现，幼龄银杉在全光照下和荫蔽林冠下比在林窗内高生长都要缓慢;成年银杉高生长盛期在130年前出现;银杉种群地上部分生物量在大部分群落类型间介于62000-91000千克/公顷之间。 第四纪冰川时期，强烈的气候变迁，造成银杉种群的大尺度减少，并导致其间断分布于我国亚热带山地;冰后期以来的气候波动及近代剧烈的人类活动使已经片断化的银杉种群数量进一步下降。从而导致银杉遗传多样性低和生殖障碍大，后者反过来又进一步引起种群数量下降和分布区缩小，形成恶性循环，造成银杉濒危。

植物对光环境的适应性研究—富贵草对模拟光斑的光合响应——银衫对不同光环境的适应性——大叶黄杨叶片内部光能利用梯度

本文研究了富贵草对模拟光斑的光合响应、银杉对光的适应性以及大叶黄杨叶片内部光能利用梯度三个方面的问题。 1)研制了用于林内光环境调查和研究的光量子计组件。 关键词：光量子计，A/D板 2)以亚热带常绿阔叶林下一种常见的灌木富贵草为研究对象，利用气体交换和叶绿素荧光技术研究了其对模拟光斑的光合响应。在同样辐射通量（非光抑制）的情况下，光合诱导过程中光斑可以提高富贵草对光斑的利用能力（光斑诱导的碳同化量可高出对照48%）。叶绿素荧光测量结果表明：1）光斑与光斑之间的暗期发生了qN弛豫过程;2）暗期之后的光期光化学能量转换效率提高。强光光斑簇可以诱导富贵草光抑制的产生，但程度较连续光低。 关键词：模拟光斑， 叶绿素荧光， 光诱导过程 3)用高效液相色谱(HPLC)和77K低温荧光发射光谱技术来研究快速诱导组分发生的时间内光斑所导致NPQ (qN)降低的生理原因。在非光抑制条件下，光斑造成的NPQ (qN)降低的生理原因包括叶黄素循环的变化及LHCIIs聚集态的变化;此外低温荧光数据还显示光斑导致的PSII/PSI荧光产量比率要高于连续光，说明光斑导致植物对于光的利用增加。以上结果说明模拟光斑诱导了富贵草内囊体膜较低水平的能态。 关键词：模拟光斑，叶黄素，聚集态 4)用气体交换等技术测定了部分银杉幼树的生理生态指标，用鱼眼镜头测定了所测叶片的林冠开度(OP)。研究了沿林冠开度梯度的银杉幼树对光的适应性。银杉幼树在林窗边缘表现出较好的适应性，包括高的ISG（综合地上部分茎生长），高的HG（当年生树高生长速率），较高的LMA（单位叶片面积干物质重），较高的Pns（单位叶片干物质水平的净光合速率），高的单位叶片的碳同化速率，较高的截获光的单位叶片的叶面积等等，可以初步确定银杉属于Gap树种：在所测定的范围内（0. 00139%-0. 0109%）TN（土壤总氮量）明显不如OP对银杉幼树生长的影响大;综合的生态可塑性指标必须考虑具体的实验地情况、选取合适的形态学和生理学的因子、并结合多个相似生长环境下的树种来进行考虑。 关键词：林冠开度，生理生态指标，生态可塑性 5)分析了湖南八面山的银杉的某些光合特性，并比较了极郁闭（ OP<4%）情况下银杉当年生叶片与大树顶端枝条(OP>30%)当年生叶片之间光合特性上的差异。极郁闭情况下银杉叶片生长出现黄化现象，但银杉幼苗又不耐强光。银杉幼苗一天的光合动态变化表明，银杉最大光合速率在早晨8:00左右，当光照超过光饱和点时，净光合速率迅速下降，其后略有回升，呈不太典型的双峰模式。气孔关闭与净光合速率的下降有密切的关系。早晨8:00到11:00间叶黄素循环运转，对光合系统起到一定保护作用。 关键词： 银杉，色素分析，光合作用 6)采用一种新方法来测量大叶黄杨叶片内部的绝对光能利用效率梯度的曲线。该方法基于光声光谱的深度分析(Depth-Analysis)理论，并结合了光纤微探测器的叶片光梯度测量结果。日本小檗(Berberis thunbergii DC.)叶片的光声光谱扫描显示了深度分析的精确性。实验结果表明：叶片内部利用光能效率最低处在栅栏组织和海棉组织之间（入射光能的0.026%-660nm红光）;越靠近叶片的上表皮和下表皮，趋势显示叶片组织利用光能效率有上升的趋势(分别为0.092%，0.036%)。因此，不同叶肉组织绝对光能利用效率是不同的，该实验结果直接证实了Han &Vogelmann 1999b所提出的假设。 关键词： PA深度分析 叶片内部的光梯度 光化学损失 光吸收梯度

Ⅰ濒危植物银杉幼树对生长光强的适应研究、Ⅱ滴灌棉田根区水分对棉花根系生长的调节研究

一． 濒危植物银杉幼树对生长光强的适应研究 银杉（Cathaya argyrophylla）是我国松科中的特有单种属植物，被认为处于濒危状态。在对银杉群落多年调查研究的基础上，针对银杉幼树生长过程对光强的需求特性，开展了银杉幼树对光的适应性研究。试验在人工培育的银杉苗圃地，采用遮荫的方法，设置不同的光环境处理（100%、45%和3%自然光强），利用气体交换技术和叶绿素荧光技术测定了3种光强下银杉叶片光合生理指标的变化，探讨了不同光环境下银杉幼树光合能力在不同季节的变化及对生长光强的响应等。结果表明，在夏季银杉生长旺盛时期，遮荫导致叶片最大光合速率（Pnmax）、羧化效率(CE)明显下降。不同叶龄叶片的下降幅度不同，在3%低光环境下，当年生叶片较1年生叶片降低幅度大。银杉幼树光补偿点(LCP)和光饱和点(L．SP)随生长光强的下降均有所降低，但低光强（3%自然光强）条件下，全晴天时实际的光辐射量高于当年生叶片光补偿点的累积时间约6h，而且距离光饱和的区域相差极大，造成全天碳同化量低，同化物累积少，严重影响了银杉幼树的正常生长：在不同处理中全光强条件下银杉幼树长势最好，45%光强条件下幼树生长减慢。冬季银杉最大光合速率（Pnmax）、羧化效率(CE)值均低于夏季，光补偿点(LCP)和光饱和点(L．SP)也较夏季降低。全光照条件下无论是当年生叶片和1年生叶片，在冬季均出现了轻微光抑制现象，适度遮荫有利于银杉抵御冬季光抑制。无论在遮荫或不遮荫条件下，冬季银杉叶片将所吸收的相对过多光能通过非辐射途经耗散出去，表现出一种光保护策略。 二．滴灌棉田根区水分对棉花根系生长的调节研究 为了探讨膜下滴灌棉花根区土壤水分对棉花根系生长的影响及地上部的关系，揭示膜下滴灌棉花节水高产的生理机理，本试验通过设置不同滴水量处理，控制根区水分供应，研究膜下滴灌棉花根区水分变化对根系生长的调节效应。结果表明，限量滴灌条件下0-40cm土层内相对田间持水率在每次滴水前下降到50%以下，难以满足棉花正常生长对水分的要求;常规滴灌在每次滴水前，根区水分保持在临界水平下限以上，可基本满足棉花根系正常生长的需要，而充分滴灌量处理根区水分偏多。水分对根系生物量的影响表现为，充分滴灌与常规滴灌处理根系生物量差异不显著，两者均显著高于限量滴灌处理。随滴水量的增加，土层中根系分布集中，土壤浅层根量所占比重增加;根系在水平方向上以棉株为中心10cm区域内根量约占总根量的80%以上。根区水分对棉株生理特性也具有一定的调节作用，常规滴灌量的根系活力在生育后期高于充分滴灌量和限量滴灌处理，且深层根系活力所占比例较高。根区水分能够调节棉花根系与地上部生长比例，限量滴灌条件下棉花受到严重的干旱胁迫，虽然根冠比升高，但根系及地上部生物量均明显降低;充分滴灌量条件下单位面积根系总量、总生物学产量在各生育时期均高于常规滴灌量和限量滴灌处理，有较高铃数，但营养器官生物量占总生物量的比例较常规滴灌量处理高，最终实收棉花产量较常规滴灌量处理的低;常规滴灌在各生育时期根冠比适宜，单位重量根系的生产力较高，棉花经济产量高和水分利用效率均较高，增产潜力大。

¿Pluralismo o colonialidad médica? Un estudio alrededor del cáncer en diferentes sistemas médicos colombianos

En esta investigación se realiza un análisis del tipo de relaciones que se establecen entre la medicina alopática y la medicina indígena yagecera en el escenario urbano de Bogotá. Para ello, toma distancia de los estudios ya realizados sobre este tema en el campo de la antropología a partir de dos aspectos: en primer lugar, busca acercarse a esta relación a partir de las trayectorias profesionales de un conjunto de médicos (tanto indígenas como alopáticos); en segundo lugar, se aproxima a estas relaciones a partir de una enfermedad particular: el cáncer.

Alterações da default mode network provocadas pela ingestão de Ayahuasca investigadas por Ressonância Magnética Funcional

Ayahuasca is psychotropic beverage that has been used for ages by indigenous populations in South America, notably in the Amazon region, for religious and medicinal purposes. The tea is obtained by the decoction of leaves from the Psychotria viridis with the bark and stalk of a shrub, the Banisteriopsis caapi. The first is rich in N-N-dimethyltryptamine (DMT), which has an important and well-known hallucinogenic effect due to its agonistic action in serotonin receptors, specifically 5-HT2A. On the other hand, β-carbolines present in B. caapi, particularly harmine and harmaline, are potent monoamine oxidase inhibitors (MAOi). In addition, the tetrahydroharmine (THH), also present in B. caapi, acts as mild selective serotonin reuptake inhibitor and a weak MAOi. This unique composition induces a number of affective, sensitive, perceptual and cognitive changes in individuals under the effect of Ayahuasca. On the other hand, there is growing interest in the Default Mode Network (DMN), which has been consistently observed in functional neuroimaging studies. The key components of this network include structures in the brain midline, as the anterior medial frontal cortex, ventral medial frontal cortex, posterior cingulate cortex, precuneus, and some regions within the inferior parietal lobe and middle temporal gyrus. It has been argued that DMN participate in tasks involving self-judgments, autobiographical memory retrieval, mental simulations, thinking in perspective, meditative states, and others. In general, these tasks require an internal focus of attention, hence the conclusion that the DMN is associated with introspective mental activity. Therefore, this study aimed to evaluate by functional magnetic resonance imaging (fMRI) changes in DMN caused via the ingestion of Ayahuasca by 10 healthy subjects while submitted to two fMRI protocols: a verbal fluency task and a resting state acquisition. In general, it was observed that Ayahuasca causes a reduction in the fMRI signal in central nodes of DMN, such as the anterior cingulate cortex, the medial prefrontal cortex, the posterior cingulate cortex, precuneus and inferior parietal lobe. Furthermore, changes in connectivity patterns of the DMN were observed, especially a decrease in the functional connectivity of the precuneus. Together, these findings indicate an association between the altered state of consciousness experienced by individuals under the effect of Ayahuasca, and changes in the stream of spontaneous thoughts leading to an increased introspective mental activity

Crab spiders (Araneae: Thomisidae) in flowering plants in a Brazilian Cerrado ecosystem

Ainda que aranhas Thomisidae sejam comumente encontradas em flores, as associações desses aracnídeos a espécies de plantas e às suas características florais foram pouco registradas na região neotropical. Observações do hábito das plantas, visitantes florais, e também das características florais, tais como antese, odor, forma, cor e recursos da flor, foram assinaladas para espécies floridas de uma área de cerrado presentes em uma trilha de 2 km de extensão. Misumenops argenteus e Misumenops pallens representaram 62,86% das aranhas habitantes de 22 espécies de plantas floridas. As plantas Senna rugosa (Fabaceae), Styrax ferrugineus (Styracaceae) e Banisteriopsis campestris (Malpighiaceae) abrigaram, individualmente, cerca de 10 a 17% do total das aranhas e, nestas plantas, a antese diurna; flores de coloração atrativa a abelhas, como amarela (S. rugosa), branca (S. ferrugineus) e rosa (B. campestris) e as anteras poricidas, bem como a visita das flores por abelhas reforçou a evidência de síndrome de polinização para melitofilia. Este é o primeiro levantamento de espécies de aranhas Thomisidae associadas a plantas do cerrado brasileiro.

A busca de si numa religião hoasqueira: oralidade, memória e conhecimento na União do Vegetal (UDV)

O presente trabalho apresenta os resultados da pesquisa etnográfica (baseada na perspectiva da participação observante) realizada junto à religião denominada União do Vegetal (UDV), tendo como locus a Região Metropolitana de Belém (PA). Uma religião de origem amazônica, a UDV está classificada como uma das três principais Linhas das Religiões da Ayahuasca, as quais, entre outras similaridades, têm em comum o uso do chá enteógeno derivado da decocção de duas espécies vegetais: o cipó Banisteriopsis caapi (mariri) e a folha Psychotria virídis (chacrona). Apresentando como recorte metodológico questões relativas ao uso da oralidade como modo exclusivo de transmissão dos ensinos, assim como os aspectos e configurações da memória para esse grupo, a pesquisa objetivou investigar de que modo essas categorias e suas inter-relações contribuem para a configuração da cosmovisão desse grupo – como uma forma de contribuir ao quadro das pesquisas sobre religiões e práticas religiosas na Amazônia.

Ayahuasca alters structural parameters of the rat aorta

Ayahuasca is a hallucinogenic brew traditionally used by Northwestern Amazonian indigenous groups for therapeutic purposes. It is prepared by the decoction of Banisteriopsis caapi with the leaves of Psychotria viridis. Banisteriopsis caapi contains β-carbolines that are inhibitors of monoamine oxidase and P. viris is rich in dimethyltryptamine, a 5-HT(1A/2A/2C) agonist. Acute ayahuasca administration produces moderate cardiovascular effects in healthy volunteers, but information regarding long-term use is lacking. This study investigated the effects of ayahuasca (2-4 mL/kg) in the rat aorta after acute and chronic (14 days) administration. Ayahuasca caused flattening and stretching of vascular smooth muscle cells and changes in the arrangement and distribution of collagen and elastic fibers. Chronic treatment with the higher dose significantly increased media thickness and the ratio of media thickness to lumen diameter. More research is needed on the cardiovascular function of long-term ayahuasca consumers.