广东省南昆山自然保护区厚叶木莲的群落特征研究

为探讨广东省南昆山濒危植物厚叶木莲(Manglietia pachyphylla)群落的结构特征,采用样方调查法对群落内的物种种类组成、区系、垂直结构和种群年龄结构等进行了研究。结果表明,在2000 m2的样地内共有维管植物236种,隶属于73科136属,以热带成分占绝对优势;优势科为樟科(Lauraceae)、山茶科(Theaceae)、壳斗科(Fagaceae)、冬青科(Aquifoliaceae)、茜草科(Rubiaceae)等。群落中以苗仔竹(Schizostachyum dumetorum)为优势种,重要值为81.09%;群落的生活型谱以中、小高位芽植物为主,占79.23%。群落属于南亚热带常绿阔叶林植被类型。群落成层现象明显,可分为乔木层、灌木层和草本层3层,层间植物丰富。对种群的年龄结构进行分析表明,厚叶木莲种群已处于衰退模式,有即将在群落中消失的可能,属于濒危物种,应加以保护。因此,对厚叶木莲及其群落在就地保护的基础上,同时要进行迁地保护及推广应用。     

四川青城山穗花杉种群和群落特征的初步研究

本文对四川省都江堰市青城山境内的穗花杉群落进行了初步研究,首次揭示了穗花杉群落和种群的基本特征．穗花杉种群具明显的增长型特征,处于良好的发育状态,其空间分布格局为集群型,其生态习性为显著的耐阴性和岩生性．穗花杉植物群落植物区系成分表现为古老性、残遗性和特有性的有机融合,群落内有维管束植物１１１种．其中热带区系成分占优势．生活型话以常绿高位芽植物为主．而其中又以常绿小高位芽和常绿中高位芽植物占优势．群落中植物叶的性质亦与常绿阔叶林相似。由于常绿针叶植物穗花村在群落中居优势地位,因此作者认为该群落是亚热带常绿阔叶林中的一类特殊群落类型。     

江西官山自然保护区巴东木莲群落特征

对江西省官山国家级自然保护区内巴东木莲(Manglietia patungensis)群落特征进行调查和分析,结果表明,保护区内巴东木莲群落物种组成丰富,区系成分复杂,热带分布属明显多于温带分布属。群落组成以高位芽植物为主,地上芽植物次之,植物叶的性质以中小型叶、单叶、革质、非全缘为主。群落地上成层现象明显,下木层物种多样性高于乔木层。巴东木莲种群结构稳定,呈集群分布。     

格氏栲自然保护区常绿阔叶林植物组成特征分析

本文在11000m²样地调查材料的基础上,分析了福建三明格氏栲自然保护区常绿阔叶林群落的植物种类组成、分布区类型和物种多样性特点。结果显示,群落共计有维管植物223种,隶属于80个科159属,其中单种属占总属数的80.5%;地理成分复杂,具有中国15个种子植物属分布区类型中的12个,且以热带亚热带成分为主,其中泛热带分布属的比例最高,其次为热带亚洲分布属,温带成分占有一定比例;群落不同层次多样性指数由大到小的变化规律为:灌木层 >乔木层 >草本层;植物分布区类型与物种多样性指数的分析表明,该群落是介于南亚热带季风常绿阔叶林和中亚热带常绿阔叶林之间的过渡类型。     

格氏栲自然保护区常绿阔叶林群落特征

在11000m²样地调查材料的基础上,分析了福建三明格氏栲自然保护区常绿阔叶林群落的种类组成、乔木种群的重要值、群落外貌、物种多样性、水平结构和垂直结构特征。该群落计有维管植物223种,隶属于80个科159属,其中单种属占总属数的80.5%,包括藤本在内的高位芽植物占总种数的85.2%。重要值高的乔木种群是格氏栲、木荷、米槠、马尾松、刮槠和山黄皮。主要乔木种群均服从聚集分布。群落垂直结构复杂,可分为乔木层、灌木层和草本层。生活型谱和物种多样性指数介于南亚热带季风常绿阔叶林和中亚热带常绿阔叶林之间。     

后河自然保护区常绿落叶阔叶混交林群落学特征研究

研究了后河国家级自然保护区常绿落叶阔叶混交林的区系特点、群落学特征。结果表明 :后河国家级自然保护区常绿落叶阔叶混交林群落物种丰富 ,有 110科 2 88属 5 34种 ,科的分布型以热带类型为主 ,属的分布型温带类型占优势 ,反映该群落区系以温带为主的亚热带区系特点 ;该混交林主要由以单叶、中型叶及非全缘叶为主的常绿、落叶阔叶高位芽植物组成 ,群落层次分明 ,从上至下 ,落叶阔叶树种所占比例逐渐减少 ,常绿阔叶树种比例逐渐增加 ;除两低海拔样地外 ,多样性变化幅度较小 ,各样地的物种多样性指数变化趋势基本一致。     

后河自然保护区常绿落叶阔叶混交林落学特征研究

研究了后河国家级自然保护区常绿落叶混交林的区系特点,群落学特征,结果表明：后河国家级自然保护区常绿叶阔叶混交林群落物种丰富,有110科288属534种,科的分布型以热带类型为主,属的分布型温带类型占优势,反映该群落区系以温带为主的亚热带区系特点;该混交林主要由以单叶,中型叶及非全缘叶为主的常绿,落叶阔叶高位芽植物组成,群落层次分明,从上至下,落叶阔叶树种所占比例逐渐减少,常绿阔叶树种比例逐渐增加,除两低海拔样地外,多样性变化幅度较小,各样地的物种多样性指数变化趋势基本一致。     

峨眉山峨眉栲、华木荷群落研究

 峨眉栲、华木荷群落是我国西南部亚热带山地常绿阔叶林群落的主要代表类型。本文从群落分布区域自然环境、群落植物组成特点、群落外貌和结构特征以及主要种群的结构及动态趋势等方面对该群落进行了较全面的探讨,并将其与我国部分同类或类似群落作了系统的比较分析,阐明了该群落的性质、特征和演变趋势。1．尽管该群落分布于我国中亚热带,但区域性环境独特,使该群落保存了较强的热带残遗性和亚热带雨林特征。2．样地调查统计有维管植物61科116属171种,区系组成复杂,地理成分以热带分布类型居多,物种多样性指数较高。3．群落外貌是由中小型叶、革质与厚革叶、单叶的常绿高位芽植物所决定。群落垂直结构较复杂,地上成层较明显,优势种显著。4．主要种群及其苗木的分布格局多呈集群分布,体现出中亚热带湿性常绿阔叶林种群个体的水平空间配置及分布特点。5．群落主要种群的年龄结构均处于增长和相对稳定状态,各年龄级的分布具有较高的生态结构水平,但仍存在种间竞争替代现象,表明群落尚处于进展演替阶段。6．各样地间种类相似性较高,群落内种类分布相对一致。乔木种间联结性具有一定规律,反映了环境梯度变化和群落种类分布关系。     

湖南大围山杜鹃灌丛的群落组成及结构特征

灌丛是陆地生态系统中最重要的自然植被类型之一, 在植被演替、生物多样性保护和维持生态平衡等方面具有重要作用。本文基于2012年的样地资料, 对湖南大围山杜鹃(Rhododendron simsii)灌丛的物种组成和群落结构进行了分析。结果表明: 群落内共有维管束植物58种, 隶属于36科50属, 其中木本植物19种, 草本植物39种, 缺乏木质藤本; 区系以温带性质为主, 兼受热带亚热带区系的强烈影响; 群落外貌矮平, 灌木层个体集中在1-2 m高度级; 植被分类上, 该群落归属于山地中生落叶阔叶灌丛, 隶属于温性落叶阔叶灌丛群系组; 生活型以地面芽和高位芽植物为主, 反映了亚热带中山山顶温凉湿润的气候特点; 群落各层次优势种明显, 具有较高的稳定性和均匀性; 高度级和基径级分析表明群落内中等大小个体具有保守的生活史策略, 优势种杜鹃为远期衰退种群。综合分析结果表明, 该杜鹃灌丛尚处于群落演替的中期或前中期, 最终将演替为亚热带中山常绿落叶阔叶混交林或常绿阔叶林。     

江西亚热带常绿阔叶林的生态学特征

笔者对江西亚热带常绿阔叶林进行了广泛的实地考察,并对其有关的生态学特征进行了分析,得出如下结果: 1.外貌是由革质,单叶,小型叶为主的常绿中高位芽植物决定的; 2.具有明显的成层现象和复杂的层片结构。常绿高位芽植物层片占优势,也有少量落叶高位芽植物层片; 3.区系成分丰富而复杂,计有维管束植物110余科、370余属、2000余种,具有与澳洲、热带美洲、热带非洲、东南亚、北美所共有的植物区系100余属,与世界各地区联系广泛且密切; 4.种群多样性指数为2—4之间; 5.群落最小面积为900米~2,最少样点为12个; 6.群落类型多,被划分为7个群系组,26个群系。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细