秦岭山地华山松林群落学特征研究

以秦岭南坡华山松群落为对象,分析了其群落特征,结果表明,华山松群落共容纳种子植物166种,分属51科111属,区系组成丰富;在植物区系地理成分上,属的分布类型以温带性质居多,共65个,占总属数的66．7％,表明了群落植物区系组成的温带亲缘;在群落外貌特征上,华山松群落高位芽植物最多,占75．9％,叶级以中型叶为主,共96种,占57．8％,叶型以单叶为主,共139种,占83．7％;群落可分为乔、灌、草3个层次,亦有层间植物伴生;随年龄增长,群落中华山松种群空间结构呈集群分布→随机分布→集群分布变化,聚块指标变化不大,其聚块面积在100m^2左右波动;种群格局强度随年龄阶段变化缓慢,处于较弱的生境异质性变化状态中;尽管缺失某些年龄阶段的幼数、幼苗现象存在,华山松林作为一个稳定群落在该区域仍占有优势地位。     

濒危植物秦岭冷杉群落数量特征及其动态

对石人山自然保护区秦岭冷杉群落特征和动态进行了研究,结果表明:秦岭冷杉群落共有种子植物61种,分属27科40属,群落垂直结构简单,可分为乔木层、灌木层和草本层。秦岭冷杉和华山松种群大、中胸径的个体占绝对优势,幼苗、幼树较少,属于衰退种群;湖北花楸小、中胸径的个体占优势,属于进展种群。通过聚类分析,将秦岭冷杉群落分为5个群丛类型:①秦岭冷杉 湖北花楸-山刺玫-结缕草群丛;②秦岭冷杉 华山松-秀雅杜鹃-藜芦群丛;③秦岭冷杉 血皮槭-黄刺玫-野菊群丛;④秦岭冷杉 华山松-箭竹-牛蒡群丛;⑤秦岭冷杉 锐齿栎-箭竹-水芹群丛。5个群丛类型均处于动态变化中,种群恢复应实行就地保护,减少人为干扰,促进天然更新。     

峨眉山常绿落叶阔叶混交林的生物多样性及植物区系初探

对峨眉山常绿落叶阔叶混交林的群落结构﹑组成﹑生物多样性及植物区系等几方面进行了研究分析。结果显示峨眉山阔叶混交林由226种维管束植物组成,其中被子植物73科137属207种, 占总种数的91.6%,是峨眉山阔叶混交林的重要组成部分;群落分层现象明显,为乔木层﹑灌木层﹑草本层和层外植物4层,其中草本层发育情况差;科分布型是以热带—亚热带﹑热带—温带为主,各占22.7%, 在属的水平上则以温带分布占绝对优势(52.9%),揭示了峨眉山阔叶混交林的区系性质是以温带为主的亚热带类型;生物多样性指数处于较低的水平,在经过人为干扰后,群落处于稳定的恢复阶段。     

秦岭火地塘林区华山松人工林与天然次生林群落特征比较

采用样地调查法对秦岭火地塘林区处于中龄阶段的华山松人工林与天然次生林群落特征进行比较研究.结果表明:(1)华山松天然次生林群落有维管束植物38科64属82种,人工林群落有维管束植物30科55属71种,两个群落共有种为53种,相似系数为0.55.(2) 华山松人工林群落灌木层和草本层的Maglef指数、Simpson指数、Shanon-Wiener指数和Pielou均匀度指数与天然次生林群落无显著差异,但人工林乔木层的4个多样性指数显著低于次生林.人工林的4个多样性指数表现为灌木层＞草本层＞乔木层的规律,天然次生林表现出灌木层＞乔木层＞草本层的规律.(3)在生活型谱上,人工林与次生林的高位芽、地上芽、地面芽、地下芽和一年生草本的差异均不显著,但是天然次生林的中小高位芽植物比例显著高于人工林,矮高位芽植物相反.(4)在垂直结构上,天然次生林乔木层的树种组成和灌木层的天然更新幼苗量较人工林丰富,两个群落乔木层华山松种群的平均高度以及乔灌草三层的盖度无显著差异.(5)在水平结构上,人工林华山松种群的空间分布格局为均匀分布,胸径一致,为纯林;天然次生林华山松种群空间分布格局为聚集分布,与华椴和锐齿栎等树种水平镶嵌,形成异龄混交林.(6)天然次生林群落的自然构成系数为3.20,顶极树种比例为34.7%,人工林群落的自然构成系数为1.49,顶极树种比例为22.7%,两个群落差异极显著,且天然次生林群落处于先锋群落的中后期阶段,人工林群落尚处于先锋群落的初期阶段.研究表明,经过40年的恢复,两个群落整体上已具有一定程度的相似性,物种组成已比较接近,灌木层和草本层已无显著差异,两者主要差异在乔木层和演替状态上,天然次生林乔木层树种丰富,群落演替速度较人工林快.     

草海国家级自然保护区华山松群落特征及物种多样性研究

为探讨喀斯特地区森林群落的演替动态和生物多样性维持机制,采用样地调查法对草海国家级自然保护区的华山松(Pinusarmandii)群落的物种组成、植物区系特征、种群结构和物种多样性等进行了分析。结果表明,样地内共有种子植物37科69属81种,其中乔木11种、灌木32种、草本38种;群落内植物的科、属区系成分类型多样,以温带成分为主;生活型谱主要以高位芽植物(46.91%)和地面芽植物(27.16%)为主;乔木层华山松的重要值达58%,为群落的单优势种;径级结构呈左偏正态型分布,树高分布集中在12～21 m,冠幅分布呈V型;乔木层与灌木层、草本层间的多样性差异显著(P0.05),物种丰富度指数S和D_M、多样性指数H和D_S均为草本层灌木层乔木层,物种均匀度指数J为灌木层草本层乔木层。因此,草海国家级自然保护区内的华山松群落特征和物种多样性具有明显的地域特点。     

外来树种华北落叶松引种对秦岭森林群落的影响

采用样地调查法对比研究了秦岭火地塘林区外来树种华北落叶松人工林与乡土树种华山松人工林及华山松天然次生林群落特征差异.结果表明:华北落叶松人工林群落与华山松天然次生林群落的相似性系数仅为0.11,华山松天然次生林与华山松人工林的物种数量均明显高于华北落叶松人工林(P＜0.01);华山松天然次生林和华山松人工林乔、灌、草层的Margalef指数、Simpson指数、Shannon-Wiener指数和Pielou均匀度指数均显著高于华北落叶松人工林( P＜0.001),而前两者之间灌木层和草本层的4个多样性指数的差异不显著(P＞0.05);华北落叶松人工林的自然构成系数最低(0.3),华山松天然次生林的自然构成系数最高(5.2),华山松人工林的自然构成系数为3.5,三者存在极显著差异(P＜0.001).说明外来树种华北落叶松引种造成秦岭森林群落物种丰富度、植物多样性和林分自然化程度降低,自然次生演替或乡土树种人工林较外来树种人工林更有利于林下植被的恢复.     

林芝云杉群落特征的研究

析了林芝云杉( Picea likiangensis var. linzhiensis )群落的种类组成、区系特征、群落外貌、垂直结构和水平结构等特性。结果表明：调查样地共有维管植物144种,隶属于53科116属,其中只含1种的属占81.03%。林芝云杉群落的区系组成、植物生活型谱、叶片性质等特征反映了群落的温带性质。群落垂直结构明显,可分为乔木层、灌木层、草本层及层间植物,乔木层郁闭度为0.4~0.8,林芝云杉大多为乔木层的单一优势种,有时与急尖长苞冷杉(Abies georgei var. smithii)、华山松(Pinus armandii)等混生,而群落植物的水平分布不均匀。优势种种群的年龄结构分析表明,该种群处于稳定状态;群落的物种丰富度为32.6364,其Shannon-Wiener指数为3.0926,Simpson指数为0.9366,均匀度指数为0.8942,且均为草本层>灌木层>乔木层。     

浙江古田山自然保护区木荷群落研究

通过对木荷群落特征进行分析,结果表明:木荷群落植物种类丰富,科属组成分散,区系成分复杂。从属的地理成分来看,热带分布的属多于温带分布的属。群落的生活型以高位芽植物为主,地下芽植物次之。该群落叶的性质以小型叶、单叶、草质、非全缘为主。群落垂直结构复杂,地上成层现象明显,可分为乔木层、灌木层和草本层,并有一定数量的层间植物。乔木层、灌木层和草本层的物种多样性大小依次为灌木层> 乔木层> 草本层。     

湖南省南岳原生性森林群落的研究——Ⅳ、包石栎锐齿槲栎林

南岳的包石栎锐齿槲栎林是一种尚未报道的类型 ,即包石栎 +锐齿槲栎 +甜槠 -箬竹 -求米草群丛。群落内有植物 63科、1 0 2属、1 2 9种 ,属的区系成分可划分为 1 3种分布区类型 ,以温带性质成分为主 ;种可划分为 1 7个种分布式样 ,以华夏、东亚、中国—日本、华东—华中、中国—喜马拉雅和华中—华南—西南 6种类型为主。木本和草本植物各占 65 .1 2 %和 3 4.88% ,常绿和落叶成分各占 1 9.3 8%和占 45 .74%。群落可划分为乔木、灌木、草本 3层 ,在更新演替过程中仍将保持常绿落叶阔叶混交林性质 ,但优势种、亚优势种可能会被其他种取代。群落物种多样性Simpson指数值与东南亚、南美和西非比较接近 ,而Shannon Weaver和α 指数值与山地季雨林水平接近。几何级数分布、分割线段模型适于拟合乔木层 ,分割线段中的多度—频度和对数正态模型适于拟合草本层 ,对数级数分布模型适于拟合任何层次。     

湖南省南岳原生性森林群落的研究 Ⅲ.长叶石栎林

湖南省南岳原生性森林群落长叶石栎林是一种尚未报道过的群落新类型,即长叶石栎＋多脉青冈－尾叶山茶－求米草群丛（Association of Lithocarpus henryi Cyclobalanopsis multinervis-Camellia caudata-Oplismenus undulatifolius）,属于典型的常绿落叶阔叶林。该群落属的区系成分主要是北温带和泛热带2种分布区类型,其中温带性质成分占主体;而种的区系成分主要是华夏、东亚、华东－华中3种分布式样,具有华东－华中区系的过渡交替色彩。群落可以明显分为乔木层、灌木层和草本层,其中乔木层又可分为2个亚层,该群落能稳定相当一段时间,更新演替过程中虽然会保持常绿落叶阔叶林性质,但其优势种可能被尾叶山茶、多脉青冈等树种取代。该群落物种多样性水平接近季雨林与稀树草原之间的水平;Shannon-Weaver、Brillouin和McIntosh等3个多样性指数及其对应的均匀度指数可能适合研究群落物种多样性;在研究群落物种多样性时必须要多用一些公式进行测定才可能避免出现错误的结果。不同的物种相对多度分布格局模型在拟合群落不同层次时其结果并不一致。     

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