怒江中游西藏境内干旱河谷荒漠植被特征

基于实地调查资料,对西藏境内怒江中游河谷的特殊荒漠型植被进行了研究。结果表明：（1）22个样方中有85种维管植物,其种子植物属的分布区类型以泛热带分布为主,占21．6％;种以中国特有分布中的西南特有成分为主,占53．2％;（2）生活型谱以矮高位芽植物为主,占41．2％,地面芽植物占40．0％;（3）采用Raunkiaer频度分析,出现在10个以上样方中的物种有白刺花、垫状卷柏、芸香草和阔盖中国蕨等,频度分别是68．2％、50．0％、50．0％、45．5％;（4）根据该河谷区域的气候特点、干旱程度、群落的生态外貌特征和生活型等,并结合《中国植被》对灌丛和荒漠的划分,认为该河谷区域的植被盖度极低,不属于灌丛类型,而是非地带性的干旱河谷型荒漠植被。     

秦皇岛市非中国特有种植物的区系分析

秦皇岛市计有野生种子植物１０９３种,隶属于１２２科,５１３属。其中非中国特有种８４７种,占总种数的７７．４％。中国特有种２４６种,占总种数的２２．６％。本对非中国特有成分作了区系分析,其中世界分布３６种,热带分布５５种,占５．２％;湿带分布５１０种, 亚分布４２４种,占２２．９％;中亚东部至华北分布（吉比中海成分）２种,占０．２％。因此,秦皇岛植物区系属于东亚和温带亚洲区系,与喧和古地中海区系有     

沈阳市区植物区系与植被类型的研究

探讨了沈阳市区植物区系特点和城市植被类型的分类及其特征,沈阳市处于长白植物区系、蒙古植物区系和华北植物区系交汇地带,植物种类较丰富,约有种子植物98科371属779种,最大科是菊科。共有植物85种,超过20种的科还有莎草科、蔷薇科、豆科、蓼科、唇形科、百合科及毛茛科等,这些科共有植物384种,占沈阳市区种子植物总数的49．3％。此区系有23个地理成分类型,其中以温带性质占优势。占沈阳市区地理成分的89．3％,根据植被发生和功能以及建群种的作用,将沈阳市区城市植被划分三大植被类14个植被组和57个植被型,并对3个植被类中的典型代表性类型进行了群落(种群)的组成、结构、动态和功能分析。     

浙江天台山七子花群落特征的初步研究

天台山的七子花林,常见的种子植物有１２５种,隶属５１科,１０２属。其中热带类型３６属,温带类型５２属。按Ｒａｕｎｋｉａｅｒ生活型统计,高位芽植物占７０．８％,地面芽植物占２２．３％,地下芽植物占４．６％,一年生植物占２．３％,高位芽植物的比例与本省常绿落叶阔叶混交林的生活型谱近似。叶级以小型叶为主,占５３．１％。叶型以单叶比例最大,占７８．５％。群落结构可分为乔木层、灌木层、草本层和地被层。     

闽北万木林植物区系研究

闽北万木林是我国中亚热带一处以常绿阔叶林为保护主体的自然保护区。植物种类丰富,计有维管束植物１６０科５８０属１１９９种。种子植物区系地理成分复杂,属的分布区类型有１３个,热带亚热带分布、温带分布和中国特有分布分别占本区野生种子植物属总数的６０．６％、３８％和１．４％。本区种子植物的９３．２％与华东区系共有,８２．７％与华南区系共有。据属的相似性系数和模糊聚类法分析,万木林与武夷山区系的关系最为密切,其次为庐山和九龙山等,再次为罗浮山和其他山地。万木林属泛北极植物区中国－日本森林植物亚区华东地区的一部分,但同时也显示了闽北由华东植物区系向华南植物区系过渡的特征。     

喀喇昆仑山-昆仑山地区植物的生活型组成

喀喇昆仑山－昆仑山地区植物生活型组成以地面芽植物为主,约占４５．１％。其次是隐芽植物（包括地下芽植物、水生植物和沼生植物）,约占１９．６％。一年生植物、地上芽植物、高位芽植物分别占１５．８％、１０．５％、９．１％。然而,不同地段的植物生活型谱存在着明显的差异。昆仑北翼山地的３个地段（Ⅰ２、Ⅰ３和Ⅰ４）俯瞰着极端干旱的塔里木盆地,又有海拔３０００ｍ以下的山地荒漠带和山地荒漠草原带,其生活型谱比较相似,表现在一年生植物所占比例均在１５％以上,高于其余５个地段的约１０％;这３个地段地面芽植物的比例约为４０％,低于其余５个地段的约５２％。植物生活型谱随海拔高度的变化规律是,高位芽植物、一年生植物和隐芽植物在生活型谱中所占比例随海拔升高而下降,地面芽植物和地上芽植物所占比例随海拔升高而增加。这个结果说明一年生植物比较适应荒漠气候条件下降水量少、年变率大的特点,而不适应高寒地区低温、生长季短的气候特点。与此相反,地面芽植物和垫状、匍匐状地上芽植物比较适应寒冷地区气温低、生长季短的气候特点,能更好地利用地表和近地面层温度较高的条件     

广西植被植物区系研究

广西植被植物区系组成有２１７科,１０２５属,乔木层优势种４３０种。分层统计,乔木层２７８属,灌木层１９８属,草本层４０３属,层间植物１４５属。９２７属种子植物有１４个分布区类型和１９个变型,热带分布占７３．０％,温带分布占２３．８％。分层：乔木层热带分布占７４．１％,温带分布占１９．８％,草本层热带分布占６８．６％,温带分布占２９．８％;泛热带分布４２．５％在草本层,２２．５％在乔木层;热带亚洲分布３７．５％在乔木层,２０．７％在草本层;北温带分布４８．４％在草本层,３０．６％在乔木层;东亚和北美洲间断分布３７．５％在乔木层,１７．５％在草本层;东亚分布４４．４％在草本层,２５．０％在乔木层。以优势种统计,热带分布占３４．８％,南亚热带分布占２８．８％,中亚热带分布占３６．３％。     

西双版纳热带山地雨林群落学特征分析

根据4块样地的调查资料,分析了西双版纳热带山地雨林的群落学特征。结果表明：在2500m^2的样地中,共计有维管束植物105～178种,分属于46～61科、80～130属。区系成分可分为11个类型,4块样地均以热带区系成分为主（约90％）,其中又以热带亚洲（印度-马来西亚）分布（23．40％～32．88％）和泛热带分布（25．20％～36．67％）的成分占优势。群落以高位芽植物为主,其中又以中（约50％）、小高位芽植物（21．30％～27．78％）占优势;在叶片特征上,群落以中叶（72．66％～82．54％）、单叶（75％～86．96％）、纸质（58．73％～62．22％）、全缘（76．67％～83．33％）、非尾尖（约90％）为主。低海拔带上山地雨林的热带区系成分以及藤本植物、中叶和全缘叶植物所占的比例高于高海拔带上的山地雨林,而小高位芽植物比例则低于后者,体现出较强的热带雨林性质。西双版纳的山地雨林与本地区的沟谷雨林、低丘雨林相比表现为热带区系成分、藤本植物、大高位芽植物以及巨叶、大叶植物较少,而温带成分、小高位芽植物、小叶植物较为丰富,体现出向常绿阔叶林的过渡特征。     

贵州梵净山国家级自然保护区藤本植物的研究——附梵净山藤本植物名录

研究了贵州梵净山国家级自然保护区藤本植物的区系及生态特性。结果表明：（1）本区计有藤本植物45科,89属,253种（含种下分类群）。（2）本区藤本植物区系起源古老而复杂,藤本区系本源广泛。其中藤本种的分布区有18个类型或亚型,热带区系成分占明显优势,为55．96％,温带区系成分占42．21％;特有分布类型占1．83％。（3）本区多年生藤本和木质藤本占绝对优势,分别占98．42％（一年生占1．58％）和78．05％（草质占20．95％）;常绿藤本占优势,为59．44％,落叶藤本占37．75％,同时也有半常绿藤本,占2．81％。（4）本区藤本植物的分布与植被类型、土壤、海拔高度、湿度、温度等环境条件密切相关;本区不同的森林类型中藤本植物的种类也不同,其藤本植物种类随海拔升高而减少,低山林带、中山林带和高山林带分布着不同的藤本植物。（5）初步编制了附生境的“梵净山藤本植物名录。     

广东阳春鹅凰嶂自然保护区种子植物区系研究

鹅凰嶂自然保护区位于广东省阳春市境内 (1 1 1°2 1′2 9″～ 1 1 1°3 6′0 3″E ,2 1°5 0′3 6″～ 2 1°5 8′40″N) ,为北热带地区。计有维管植物 2 1 0科 75 4属 1 5 80种 (包括亚种与变型 ) ,其中种子植物有 1 72科 681属 1 44 8种。研究分析和讨论了本区主要植被类型、种子植物区系及珍稀濒危植物 ,其种子植物区系特征是 :种类组成比较丰富 ,地理成分复杂 ,联系广泛 ,以热带成分占绝对优势 ,是典型的热带北缘区系性质 ;植被类型以山地雨林为主 ;区系起源古老 ,原始类群丰富 ;特有性比较高 ,珍稀濒危植物明显。建议对一些濒危物种采取有效的保护措施。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.