38 resultados para Invasion
Resumo:
我国的蕨类植物资源十分丰富,约有2600多种,占全世界12000种的1/5强,其中许多种具有很高的观赏价值。在欧美的一些国家,蕨类植物已经成为花卉行业的一个重要组成部分,早已进入家庭居室、宾馆、商场、办公楼和其它公共场所,绿化和美化人们的生活环境。到目前为止,全世界共已栽培成功观赏蕨类植物700多种(品种),而我国仅有十多种投入花卉市场作为盆景和切花配叶,尚未形成一定的规模。繁殖技术不过关是造成蕨类植物在我国花卉市场难以迅速发展的障碍之一。目前国内对蕨类植物的需求主要靠野外采挖得以满足,对野生蕨类植物资源造成严重的破坏,再加上自然生态环境的恶化,致使许多物种濒临灭绝。因此,加强相关的基础研究、繁殖技术和外界环境对蕨类植物影响的研究,对蕨类植物资源的利用和保护具有重要的研究价值和现实意义。 作者在近五年的研究过程中,建立了蕨类植物孢子无菌培养技术,观察记录了蕨类植物配子体的形态发育,为建立蕨类植物快速有效的繁殖技术体系打下了良好的基础。在此研究基础上,探讨了对蕨类植物生长发育构成威胁的外界环境之一—外来入侵植物紫茎泽兰对蕨类植物的生长发育的化感作用。紫茎泽兰为目前国际上研究的热点入侵植物之一,对我国农业、林业等已造成很大破坏,并对蕨类植物资源构成一定威胁。蕨类植物配子体发育过程是蕨类植物生活史中相对脆弱的环节,最容易受化感作用的影响。但迄今为止,国际上尚未开展任何紫茎泽兰对蕨类植物(包括孢子体阶段和配子体阶段)的化感作用的研究。为保护蕨类植物自然资源,填补这一研究领域的空白,开展了紫茎泽兰对蕨类植物配子体发育过程的化感作用的研究。实验结果如下: (1)建立了金毛狗(已被列入《濒危野生动植物种国际贸易公约》(CITES)附录II 名单)、凤尾蕨属植物如傅氏凤尾蕨、剑叶凤尾蕨、蜈蚣草、银脉凤尾蕨、溪边凤尾蕨、疏裂凤尾蕨、西南凤尾蕨等多种蕨类植物的孢子无菌培养技术体系。 (2)采用无机培养基培养、土壤培养和滤纸培养三种培养方法,显微镜下观察傅氏凤尾蕨、剑叶凤尾蕨、蜈蚣草、银脉凤尾蕨、溪边凤尾蕨、疏裂凤尾蕨、西南凤尾蕨、三角鳞毛蕨、乌毛蕨、普通针毛蕨、金毛狗的孢子萌发及配子体形态发育的整个过程,研究了上述蕨类植物孢子萌发的类型、配子体各发育阶段的形态特征以及到达每个发育阶段所需的时间,为蕨类植物的繁殖技术提供了科学的依据,同时为蕨类植物系统进化和形态分类学研究提供了重要的基础资料。 (3)以金毛狗、普通针毛蕨、疏裂凤尾蕨为受体植物,研究了紫茎泽兰对这三种蕨类植物的配子体发育的化感作用。选择蕨类植物孢子萌发、假根生长、配子体形态、配子体发育各阶段及所占比例为测定指标,结果表明:紫茎泽兰根、茎、叶提取液可以对这三种蕨类植物的配子体发育产生不同程度的化感作用。表现为:延迟这三种蕨类植物的孢子萌发,降低其孢子萌发率,抑制假根的伸长,并且上述抑制作用随紫茎泽兰提取液浓度的升高而增强。随着紫茎泽兰叶水提液浓度的升高,金毛狗配子体发育阶段会滞后。在紫茎泽兰根提取液处理下,普通针毛蕨配子体上的假根发生畸变。随着时间的推移,这种现象削弱或基本消失。随着根和叶提取液的浓度升高,普通针毛蕨配子体发育阶段将会滞后。高浓度的紫茎泽兰根提取液能改变疏裂凤尾蕨的配子体的形态,并使疏裂凤尾蕨的配子体发育阶段滞后,浓度越高效果越显著。这三种蕨类植物在受到紫茎泽兰化感作用的影响后表现不同,推测与它们对紫茎泽兰所含有的化感物质的不同敏感度有关。
Resumo:
本文比较系统地综述了生物入侵研究的主要领域的最新发展,以使读者对入侵生态学的研究内容和研究范畴有比较完整的了解。生物入侵涉及到遗传学、种群生态、群落生态、景观生态、区域生态乃至全球生态各个尺度的生态学问题,同时由于生物入侵而暴露出来的问题为各个生态和生物学科的研究范围扩展和理论体系的补充都提供了极其重要的机会,从这方面讲,不宜将入侵生态学研究与其他生态学分支分离开来;然而,从生物入侵对全球生物系统和人类社会的影响范围和程度看,它应当受到政府、各行业人士和学者的重视超出一般的生态学理论研究,因此应当认为它是一个新的应用生态学分支,把它称为入侵生态学并作为一个学科来描述其理论框架和研究内容,也是为了唤起更多人对这一全球环境变化组成之一的重视。 本文分10章,由生物入侵的发生过程这一主线贯穿始终。第一章对生物入侵有关概念和入侵生态学的主要研究内容做介绍;第二章概述全球生物入侵发生的程度和一些典型生境的入侵情况:第三章分析了影响生物入侵成功的各类生物的、非生物的因素,并介绍了一些有关生物入侵的学说;第四章总结了生物入侵涉及的遗传学问题,尤其是快速进化的发生基础和影响;第五章分析了目前入侵研究中植物群落的多样性和可入侵性关系的研究中存在的主要问题和未来应当改进的地方;第六章重点介绍了入侵种扩散的主要模型类型和各自的特点及选择标准;第七章讨论了入侵种在区域尺度的扩散历史重建中存在的数据获得途径、空间格局分析、长距离传播估计几方面的问题。第八章简要介绍入侵种在生态系统水平的影响和生态系统服务评价,并举例说明如何评价入侵种造成的生态系统服务评价,及生物入侵的经济分析程序。第九章重点介绍了建立综合性的生物入侵预警系统的主要理论基础,并总结了对付外来入侵种的策略。第十章提出生物入侵在全球范围内的作用和全球生物同质化后果,并初步总结了全球变化的各主要成分间的相互作用。 全文尽量采用小标题的方式将相关内容归纳到一处,以便于读者理解。当涉及到一些即使在其他生态学分支中也称得上比较前沿内容,尽量做简要的介绍,感兴趣的读者可以进一步查阅相关文献。作者希望更多地采用最新的参考文献,但目前文献增长速度之快,要穷尽所有新观点和新方法等是不可能的,因此,希望能得到多方面的反馈信息,也期望相关人员有机会不断对本文进行补充了修改。
Resumo:
生物入侵作为全球变化的一部分,已经引起广泛的关注;而群落可入侵性是生物入侵研究的核心和热点问题之一。本文以原产墨西哥,广泛入侵我国西南地区的紫茎泽兰(Eupatorium adenophorum)为例:首先,对西南地区被紫茎泽兰入侵的群落和生境进行了分类;然后,就地形、本地植物物种多样性、环境梯度等对群落可入侵性的影响进行了探讨;最后,对紫茎泽兰的空间分布格局进行了模拟和预测。 在小尺度上,紫茎泽兰入侵与本地植物物种多样性呈负相关,表明资源的可利用性可能是调节群落可入侵性的主导因素;本地植物物种多样性在群落演替过程中和入侵的早期抑制紫茎泽兰入侵;在大的尺度上,物理环境的变异超过了内在生物因子的重要性,本地植物物种多样性与紫茎泽兰入侵成功呈正相关。 紫茎泽兰主要通过公路和河流在我国西南地区入侵和扩散;资源的可利用性是影响公路和河流两侧群落可入侵性的关键因子。 紫茎泽兰分布中心主要在沧源、元江和西昌;位于分布区边缘的乐业、重庆和泸定有可能成为新的分布中心,并对邻近地区,尤其北面和东面的区域形成繁殖体压力;紫茎泽兰整体上有向东和向北扩散的趋势。目前主要分布在云贵高原,将来的分布区还将以云贵高原为核心。
Resumo:
城市化是引起生物多样性降低的主要原因之一,因此,应特别注意城市区域和城市化过程中的生物多样性保护。北京近三十年来经历了最为持久的城市化过程,城市的迅速扩张,人口的快速增加和经济的蓬勃发展给北京的生态环境带了巨大的压力,也给生物多样性工作带来了巨大的挑战。为有效开展生物多样性保护工作,迫切需要开展北京生物多样性现状及保护对策的研究。北京市以前在生物多样性方面作过大量工作,但缺乏系统的整理。本文通过深入的现场调查和对已有文献资料的整理,对当前北京市维管植物多样性现状及问题作了分析,并提出相应对策,以期为北京生物多样性保护工作提供参考。主要内容如下: 1.北京市自然生态系统主要有森林生态系统、灌丛生态系统、草甸生态系统和湿地生态系统4种类型。在人类长期干扰下,各生态系统多为次生。目前森林生态系统面积逐步扩大,而草甸生态系统和湿地生态系统受人为活动破坏严重,呈现严重退化趋势。 2.整理关于北京物种新纪录的各种文献,结合野外调查,构建了北京维管植物多样性数据库。北京维管植物多样性比较丰富,已知维管植物有2276种,然而特有性不强,严格属于北京特有维管束植物仅有5种。境内共分布有25种国家重点保护植物,包括野大豆、紫椴、河北梨以及22种野生兰科植物。根据调查资料初步评估,确定40种植物在北京处于受威胁状态。 3.根据北京人口密度、城市人口比例以及建设土地比例,将北京市按城市化程度的高低划分为城区,近郊区、远郊区三个区域。物种丰富度以远郊区最高,城区次之,近郊区最低,而外来物种比例则以城区最高,远郊区最低。城区分布有北京市93%以上的外来种,是其物种丰富度较近郊区为高的原因之一。对北京市特有植物、受危植物、国家保护植物和北京市保护植物的分布的分析表明,远郊区分布有93%以上的上述植物,是北京市生物多样性的重点保护区域,而城区和近郊区也分别分布有近1/4和1/3,说明保护稀有濒危物种方面,城区和近郊区也不容忽视。 4.对北京市外来植物作了分析,认为北京有126种归化植物,其中47种为入侵植物。菊科、禾本科、大戟科和苋科在入侵植物中占优势,美洲为最大起源地,其次为欧洲。园艺苗木引种是入侵物种的主要侵入途径,导致海淀、丰台、西城、朝阳等城区分布有较多的入侵种。 5.对外来物种火炬树的地理分布格局和入侵潜力作了研究。火炬树在人为大力推广下已遍布各风景区,在公路两侧也常见分布并侵入农田,甚至出现在某些自然保护区。火炬树在贫瘠和肥沃生境下均具有较高的繁殖速度,在3年内靠克隆繁殖扩散距离已超过6米,并能行成郁闭度很高的单优群落,其物种丰富度、个体密度以及物种多样性指数均显著低于本地荆条灌丛群落。由于其强阳性生长特性,使其不能侵入森林,然而却能对灌丛生态系统构成危害,其克隆繁殖的特点也使其难以根除,在北京地区具有潜在的入侵能力,不适合继续作为绿化北京的主要树种。 6.北京市生物多样性面临的主要问题包括城区本土生物多样性低、生态系统退化、湿地萎缩、污染严重、强度的旅游开发和外来物种入侵等。本文对这些问题作了分析,提出在城区大力应用本地种构建自然群落,对退化生态系统因势利导结合人工和自然力进行恢复,规范旅游活动向生态旅游方向发展,加强公众教育,促进全社会参与生物多样性保护工作。
Resumo:
在云南省澜沧县对草地、以紫茎泽兰群落以及次生林地中的土壤动物一步甲和蚯蚓群落进行动态取样调查,来探讨紫茎泽兰入侵后对群落结构、生物多样性的影响。 在紫茎泽兰和草地群落中共捕获2253头步甲,35个种,其中草地上捕获1574头步甲,28个种,紫茎泽兰样地中有679头步甲,34个种;紫茎泽兰群落中步甲个体数量少,但物种数多,多样性也比较高;草地中步甲优势物种为Harpalus indicus和Tetragonoderus arcuatus占总数的59%;而紫茎泽兰中的优势物种比较分散;紫茎泽兰群落中步甲个体体型较大,而草地中体型小的步甲所占比例较高;步甲分布与落叶层厚度、土壤全磷含量、植被高度、地上生物量及土壤pH和土壤全钾含量有一定的相关性;紫茎泽兰群落与草地中的指示物种也不同,Hyphaereon masumotoi和Cosmodiscus sp.是紫茎泽兰的指示物种,而草地的指示物种有Aephnidius adelioides,Tetragonoderus arcuatus,Harpalus indicus,Harpaliscus birmanicus,Chlaenius cambodiensi。 受紫茎泽兰入侵的林地边缘步甲群落的分布规律表明,步甲个体数量排序:林地内部>紫茎泽兰群落>林地边缘:三者步甲优势种的组成,既有交叉也有区别;三者的步甲物种数及多样性指数差异不显著,步甲群落的时间动态也相似;林地边缘、内部及紫茎泽兰群落在步甲个体体型结构上差异不大,具有指示作用的步甲种少。 在草地、紫茎泽兰及次生林地三种植被类型中,共采集到3546条蚯蚓,8个种。其中,紫茎泽兰群落有1663条蚯蚓,远高于次生林及草地。多裂远盲蚓和娇小远盲蚓是当地蚯蚓群落的优势种;紫茎泽兰入侵地的蚯蚓物种数、Shannon-Wiener多样性指数大于草地及次生林地;蚯蚓数量及生物量的时间动态受月份降雨量的影响很大,体型大小不同的蚯蚓受降雨变化影响的程度不同:蚯蚓的分布与落叶层厚度、土壤全氮含量、土壤pH及有机质含量相关性较强;蚯蚓群落中只有大唇远盲蚓是紫茎泽兰样地中的指示物种。 在紫茎泽兰控制实验样地内,步甲的数量及物种数的排序是原始紫茎泽兰>半密度紫茎泽兰>去除处理。优势物种都为Anisodactylus karennius,所占比例高,其在原始紫茎泽兰群落中的分布数量远高于半密度及去除样地;步甲群落多样性指数(H’)和物种数差异不显著;三种处理的步甲群落时间动态不同,表现出不同的高峰期;Galeritula feoe和Nanodiodes piceus是原始和半密度紫茎泽兰样地中的指示物种。 总之,紫茎泽兰入侵相对单一草地后,会引起步甲个体数量下降,物种数和多样性上升,群落结构发生很大变化;紫茎泽兰入侵的林地边缘及外部草地后,林地边缘的环境变化幅度减小,林地的边际效应趋于不明显;紫茎泽兰单优群落有利于蚯蚓生存于生活,与草地及林地相比,能增加蚯蚓鲜重及多样性水平。
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存在明显的季节性干旱的实验地的自然生境(无遮荫不补水处理)对于1年生紫茎泽兰来说具有胁迫作用,而对于本地草本植物群落来说,这样的季节性干旱并不存在胁迫作用;在单层遮荫不补水的处理中,紫茎泽兰具有竞争优势,而单层遮荫补水处理对紫茎泽兰的竞争不利。在双层遮荫补水的处理中,紫茎泽兰表现出对本地植物较大的相对竞争优势,但双层覆盖对于二者的生长均构成了较严重的胁迫。 在无覆盖不补水的处理中,紫茎泽兰定居期的死亡率最高,而定居后的生长指标(平均高和平均单株干重)在补水和不补水条件之间没有明显差异;在双层覆盖条件下,紫茎泽兰存活率在补水和不补水条件下,绝对值都较高,而平均单株干重在补水和不补水条件下都比较低;在单层覆盖条件下,紫茎泽兰存活率在补水和不补水条件下都较高,紫茎泽兰的平均高和平均单株干重在不补水处理都显著高于补水处理,而且明显高于其他不覆盖、双层覆盖的补水和不补水处理。说明在实验地的自然生境中,本地群落对紫茎泽兰早期(侵入定居)具有一定的抵抗力,但在这样的生境中的本地植物群落对紫茎泽兰的后期(定居之后)的发展的抵抗力较低;双层覆盖条件(相当于郁闭度高的林下生境)对紫茎泽兰的早期侵入定居虽然抵抗力较差,但是对紫茎泽兰的后期(定居之后)的发展具有较强的抑制作用;单层覆盖条件(相当于受到人畜干扰的郁闭度较低的林下生境)下,本地群落对紫茎泽兰早期侵入定居和后期(定居之后)的发展抵抗力都很低,这一结果提醒我们,紫茎泽兰易于侵入受到过人为干扰的郁闭度较低的林下生境并产生严重危害。 刈割干扰对紫茎泽兰的入侵具有明显的促进作用,高强度刈割的促进作用主要体现在促进紫茎泽兰的个体生长速度和群体生物量上,但低强度刈割的促进作用主要体现在入侵定居的个体数量和群体生物量上。低强度刈割处理中的紫茎泽兰的密度为高强度刈割处理的5倍,单位面积上的紫茎泽兰的生物量最高,达到高强度刈割处理的2.5倍,可见对于紫茎泽兰的入侵而言,低强度的刈割干扰比高强度刈割干扰具有更大的促进作用。 本地植物雀麦、豆科植物、鱼眼草和香薷在与紫茎泽兰混栽后,它们的根际土壤微生物群落结构与紫茎泽兰根际土壤微生物相似性更高,而偏相关分析结果表明,豆科植物和鱼眼草的根际土壤微生物群落结构的变化与它们的生物量生长具有一定的关联性,而对于雀麦和香薷的根际土壤微生物群落结构的变化与它们的生物量生长的关联性不明显,说明紫茎泽兰入侵本地植物群落后可以对生态系统的土壤微生物群落结构造成较大的影响,而微生物的改变并不是对所有的本地植物来说都是非常严峻的。虽然我们实验中的4种本地植物中只有2种本地植物的生长表现出与其根际土壤微生物变化的显著相关性,但这对于本地植物群落已经是非常严重的威胁。
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By Sephadex G-50 gel filtration, Resource Q anionic exchange and C4 reversed phase liquid high performance liquid chromatography, a proteinase inhibitor protein (Ranaserpin) was identified and purified from the eggs of the odour frog, Rana grahami. The protein displayed a single band adjacent to the molecular weight marker of 14.4 kDa analyzed by SDS-PAGE. The inhibitor protein homogeneity and its molecular weight were confirmed again by MALDI-TOF mass spectrometry analysis. The MALDI-TOF mass spectrum analysis gave this inhibitor protein an m/z of 14422.26 that was matched well with the result from SDS-PAGE. This protein is a serine proteinase inhibitor targeting multiple proteinases including trypsin, elastase, and subtilisin. Ranaserpin inhibited the proteolytic activities of trypsin, elastase, and subtilisin. It has an inhibitory constant (K-i) of 6.2 x 10(-8) M, 2.7 x 10(-7) M and 2.2 x 10(-8) M for trypsin, elastase, and subtilisin, respectively. This serine proteinase inhibitor exhibited bacteriostatic effect on Gram-positive bacteria Bacillus subtilis (ATCC 6633). It was suggested that ranaserpin might act as a defensive role in resistance to invasion of pests or pathogens. This is the first report of serine proteinase inhibitor and its direct defensive role from amphibian eggs. (C) 2007 Elsevier Inc. All rights reserved.
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The Global Invasive Species Database, GISD, comprises 27 species of the most significant invasive alien insects in the world (through November, 2005), 6 of which are originally native to China, 11 are established in China, and 10 have a potential invasion
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While it has been widely suggested that freshwater fishes from East Asia invaded the western Palaearctic, details about this process are largely unknown. Here, using the cytochrome b gene, we evaluated the phylogenetic relationships of a small group of Eurasian primary freshwater fishes (Cobitidae), which are widely distributed and species rich in East Asia and Europe, with the purpose of inferring their invasion process of Europe from East Asia. Though phylogenetic relationships of cobitids were not well resolved, our analysis could identify three sister groups formed by the European and East Asian cobitids, which brought new insights into the biogeography of the genera Cobitis, Misgurnus, and Sabanejewia. The present results support the view that Asian cobitid fishes may have invaded Europe at least five times independently, and once reverse colonization of European cobitids to East Asia could also be found. Ancestral Sabanejewia might have been the first cobitids to cross Siberia and invade the EMZS (Euro-Mediterranean zoogeographic subregion) about 33.54 million years ago (MYA). One lineage of Cobitis and the ancestor of Misgurnus fossilis (Linnaeus) almost in the same time invaded the Europe, responding to 16.71 MYA and 16.59 MYA, respectively. Three different lineages of Cobitis were found to have invaded the EMZS from East Asia, and once reverse invasion to East Asia occurred to one subclade of European Cobitis. And our data also suggest that the diversity of East Asian cobitid fishes, especially of the genus Cobitis, is greatly underestimated.
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We studied diet composition and overlap of the exotic noodlefish (Neosalanx taihuensis) and the endemic fish Anaborilius grahami in a deep, oligotrophic lake in the Yunnan Plateau. A. grahami dominated the fish community in Lake Fuxian before the invasion of N. taihuensis in 1982, but it is now in the process of extinction, corresponding with an explosive increase in N. taihuensis population. Schoener's index (alpha=0.773) indicate that N. taihuensis and A. grahami have significant diet overlap, with both fish feeding mainly on zooplankton. An increased proportion of littoral prey, such as Procladius spp., Coleoptera, and epiphytes, in the diet of A. grahami indicated that this endemic fish shifted its main habitat from the off-shore zone in the late 1980s to the littoral zone at the present. A difference in reproduction between the two fishes, along with the overfishing, may have exacerbated the occupation of A. grahami's pelagic niche by N. taihuensis. The endemic species has shown large competitive disadvantage for food and space in the presence of N. taihuensis.
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Antimicrobial peptides (AMPs) are important components of the host innate immune response against microbial invasion. In addition to the previously known four classes of antimicrobial peptides, a fifth class of antimicrobial peptides has been recently identified to include NK-lysins that have a globular three-dimensional structure and are larger with 74-78 amino acid residues. NK-lysin has been shown to harbor antimicrobial activities against a wide spectrum of microorganisms including bacteria, fungi, protozoa, and parasites. To date, NK-lysin genes have been reported from only a limited number of organisms. We previously identified a NK-lysin cDNA in channel catfish. Here we report the identification of two noveltypes of NK-lysin transcripts in channel catfish. Altogether, three distinct NK-lysin transcripts exist in channel catfish. In this work, their encoding genes were identified, sequenced, and characterized. We provide strong evidence that the catfish NK-lysin gene is tripled in the same genomic neighborhood. All three catfish NK-lysin genes are present in the same genomic region and are tightly linked on the same chromosome, as the same BAC clones harbor all three copies of the NK-lysin genes. All three NK-lysin genes are expressed, but exhibit distinct expression profiles in various tissues. In spite of the existence of a single copy of NK-lysin gene in the human genome, and only a single hit from the pufferfish,genome, there are two tripled clusters of NK-lysin genes on chromosome 17 of zebrafish in addition to one more copy on its chromosome 5. The similarity in the genomic arrangement of the tripled NK-lysin genes in channel catfish and zebrafish suggest similar evolution of NK-lysin genes. (c) 2005 Elsevier Ltd. All rights reserved.
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UV-inactivated grass carp hemorrhage virus (GCHV) can induce high titer of interferon in cultured CAB (crucian carp (Carassius auratus L.) blastulae) cells, and thus defend host cells against the virus invasion. The mechanism is proposed that an antiviral state should be established in the host cells by activating expression of a set of antiviral-relevant genes. In this study, suppressive subtractive hybridization is applied to constructing a subtracted cDNA library with mRNAs isolated from UV-inactivated GCHV infected and mock-infected CAB cells. 272 differential cDNA fragments are identified by both PCR and dot blot from the subtractive cDNA library. Sequencing analysis reveals 69 genes, including 46 known gene homologues, and 23 unknown putative genes. The known genes include the genes involved in interferon signaling pathways, such as Stat1 and Jak1, the antiviral genes, such as Mx and Viperin, and a set of interferon-stimulated genes observed in mammalian cells. Most of the unknown putative genes contain AU-rich element in their sequences. Differential expressions of these genes are further confirmed by virtual Northern blot and RT-PCR. The data imply that UV-inactivated GCHV is not only able to induce production of interferon in the infected CAB cells, but also leads to the expression of a series of antiviral-relevant genes or immune-relevant genes, and therefore reveals that the signaling pathway of interferon system and antiviral mechanism in fish are similar to those in mammals.
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本文简要地阐释了化感作用的含义、基本特征以及作用机制,并结合生物多样性理论,综述了化感作用研究中化感物种的多样性、化感物质的多样性及其释放途径的多样性,具体讨论了化感作用对物种多样性、遗传多样性及生态系统多样性中的种群生态、协同进化、土壤生境、生态系统功能和生物入侵等方面的可能影响。文中提出了化感作用的利用、管理应与生物多样性保护相统一的看法,并指出对化感作用与生物多样性的关系以及相互影响机制进行本质的探索,特别是对植物化感作用的生态服务功能与价值评估与探讨,可为保护生物学和系统生态学提供理论基础,这也是今后工作开展的一个重要方向。
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Antimicrobial peptides (AMPs) are important components of the host innate immune response against microbial invasion. They are usually characterized by their small-size, heat-stability and broad range of antimicrobial activity. This review covers research advances on marine mollusc AMPs, specifically those isolated from mussels, scallops, oysters, venerid clams and abalone, which mainly include MGD, mytilin, myticin, mytimycin, big defensin, and RPD-1. Their structural characteristics, antibacterial activity, and expression pattern as well as peptide distribution and their release following microbial challenge are also discussed. In addition, the prospect of the application of AMPs as food additives or their use in immunostimulation to prevent diseases of aquatic animals, as well as their potential hazards, are also discussed.
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Peritrophin, one of the components of the peritrophic matrix, was first isolated from the intestine of insects. It is thought to protect insects from invasion of microorganisms and to stimulate digestion of food. Peritrophin-like proteins have also been found in crustaceans, as a component of the egg layer. In this study, one fragment of the peritrophin-like gene was obtained from fleshy prawn (Chinese shrimp) (Fenneropenaeus chinensis) by panning the T7 phage display library constructed with the shrimp hemocyte cDNA. The total sequence of the peritrophin cDNA was cloned by modified SMART cDNA and LD-PCR methods. The full cDNA is 1048 bp and the deduced protein is composed of 274 amino acids, including 21 amino acid signal peptide, and four peritrophin A domains and the latter three forming three chitin-binding domains. Similarity analysis results showed that the peritrophin-like protein from F chinensis has significant similarities with peritrophin-like and cortical rod proteins from other shrimp. It was inducing expression in hemocytes, heart, stomach, gut, and gills of the infected shrimp, and constitutive expression in the ovaries. No expression signal was detected in the hepatopancreas of either infected or noninfected shrimp. The recombinant peritrophin-like protein has the activity of binding Gram-negative bacteria and strong binding activity to chitin. Therefore, the bacteria and chitin binding activities of the peritrophin-like protein suggest that it may plays a role in immune defense and other physiological resposes. (c) 2005 Elsevier Ltd. All rights reserved.