云南高原地区种子植物区系

云南高原地区是一个十分自然的植物区系地区、其种子植物区系约有５５４５种,隶属于１４９１属和２４９科中,基本上是亚热带性质,本地区水平及垂直替代现象明显,地理联系广泛,但与中国－喜马拉雅亚区不同区系地区联系密切,显然是中国－喜马拉雅区系成分的发源地。根据特有种丰富程度以及一些自然地理特征,云南高原地区在区系上可以划分３个小区;滇中高原小区,澜沧红河中游小区和滇东南小区,它们之间在许多方面有明显差异。     

滇中小百草岭多变石栎林植物区系的初步研究

多变石栎林是小百草岭地区亚热带山地植被垂直带上最具特征性的植被类型 ,也是该地区州级自然保护区境内面积最大、保存最为完整、最有保护价值的植被类型。通过该植被类型中 116种常见种和优势种的群落结构和植物区系分析表明 :仅有中国特有分布种和中国-喜马拉雅分布种能贯穿于该植被类型的整个群落结构之中 ,植物区系成分以热带亚洲、中国 -喜马拉雅和中国特有类型为主 ,表明它隶属东亚植物区 ,中国 -喜马拉雅森林植物亚区 ,云南高原地区 ,云南高原亚地区 (IIIE13a)的一个具体区系单元的基本特征 ;其中的中国特有种又以小百草岭与周边的滇西北、川、黔、藏地区 (主要为横断山地区 )所共有的种占优势 ,从而也表明了小百草岭种子植物区系与横断山植物区系的联系相对紧密 ;通过与周边地区相同植被类型的比较 ,显示其地处滇中高原北缘的地理位置及受金沙江干热河谷气候影响使得该植被类型垂直分布海拔较高 ,更偏“干”的特点。     

云南哀牢山地区种子植物区系研究

依据采集的4 000余份标本及馆藏标本的整理和鉴定,云南哀牢山地区有野生种子植物199科945属2 238种215变种(亚种).植物种类十分丰富,是云南植物多样性最为丰富的地区之一.种子植物区系总体上是亚热带性质,其热带科占70.47%,热带属占63.89%,热带成分虽多于温带成份,但相当数量温带成分的存在反映了该区系具有从热带向温带的过渡性质.该植物区系缺少典型热带成分,但具有不少东亚特征科属.因此,该植物区系在区划上仍属于东亚区中国-喜马拉雅植物亚区,云南高原地区,属于东亚植物区系的一部分.     

古地中海退却与喜马拉雅-横断山的隆起在中国喜马拉雅成分及高山植物区系的形成与发展上的意义

横断山-喜马拉雅植物区系的开端是在晚白垩纪和早古近纪(早第三纪).古植物资料表明在古近纪初期横断山-喜马拉雅植物区系是同古地中海沿岸一致的以照叶林为主的暖湿植物区系.古近纪后期和新近纪(新第三纪)以后古地中海气候逐步旱化,原来的暖湿植物区系在地中海地区逐步消失,而在横断山及喜马拉雅和东亚其他地区得以保存和发展,现代横断山及东喜马拉雅的亚热带森林即是其后裔.古近纪中期以后由于古地中海的逐步退却,气候变得干旱,原暖湿植物区系逐步被现代旱生的地中海植物区系所取代.新近纪以后,旱生的现代地中海植物区系由于喜马拉雅和横断山的隆起而转向适应高山环境,逐步分化形成了现代的中国-喜马拉雅成分.横断山-喜马拉雅地区硬叶高山栎林的起源;铁筷子属,绿绒蒿属,芒苞草属,假百合属及马桑属的地中海、喜马拉雅-横断山间断分布的形成便是古地中海植物区系残遗的体现;黄花木属、独一味属等众多中国喜马拉雅成分就是古地中海祖先的后裔.这些代表类群的分析研究表明现代的喜马拉雅-横断山的高山植物区系以及中国-喜马拉雅成分中有相当的一部分是起源于新生代旱生的地中海植物区系.     

西藏植物区系地理区域分异的探讨

本文应用数量统计方法及植物区系分布区型谱图探讨西藏植物区系地理的地域分异。中国-喜马拉雅成分在藏东和藏东南占优势,热带成分集中分布于喜马拉雅南翼的低海拔地区;在高原内部青藏高原成分占统治地位,而中亚成分则在高原的西北部起重要的作用。植物区系成分的这种水平地域分异和西藏境内自东南向西北植被由森林、草甸、草原至荒漠的地带更迭是相吻合的。海拔1800米可以看作是热带成分占优势的垂直系列的上界。根据优势植物区系成分确定的几条界线,西藏可划归如下植物区系区域:古热带植物区印度马来亚植物亚区的喜马拉雅南翼亚地区,泛北极植物区的中国-喜马拉雅亚区和青藏高原亚区。     

云南巧家药山的珍稀树种

巧家药山位于云南东北部,是五莲峰山脉的最高峰,也是滇东北的最高峰,海拔4040米。站在巧家药山的山顶向东和向南远眺,没有任何高山能挡住人们的视野。在植物区系分区上,云南巧家药山位于中国-喜马拉雅森林植物亚区和中国-日本森林植物亚区的过渡地带,也是华中地区、云南高原地区和横断山脉地区的过渡地带。由于植物区系和气候类型的过渡性以及生态环境的多样性等原因,云南巧家药山云集了一组珍稀濒危特有树种,特别是被子植物中离生心皮类的珍稀濒危树种。在同一座山上同时云集西康木兰、领春木、水青树和连香树等离生心皮类的珍稀树种的现象…     

永德大雪山中山湿性常绿阔叶林植物区系的初步研究

中山湿性常绿阔叶林是永德大雪山亚热带山地植被垂直带上最具特征性的植被类型,也是该地区面积最大、保存最为完整、最有保护价值的植被类型。从该类型植被中219种常见和优势植物的种类结构分析看,只有热带亚洲成分、中国-喜马拉雅成分及中国特有成分能够贯穿于乔木Ⅰ、Ⅱ、Ⅲ层,灌木层,草本层和层外植物各层次之中;其区系成分以中国-喜马拉雅和中国特有成分占优势,同时热带亚洲成分也占有相当的比例,说明其区系具有亚热带向温带过渡的性质;而中国特有种的进一步分析亦表明其区系的过渡性质。这表明永德大雪山处于中国-喜马拉雅森林植物区系和热带亚洲植物区系的分界面上,其植物区系的过渡特征非常明显。通过永德大雪山中山湿性常绿阔叶林与邻近地区同类型植被的优势种和主要伴生种的比较,我们初步认为该地此类森林植被环境更“温湿”。     

北极-第三纪成分在喜马拉雅-横断山的发展及演化

通过古植物学及古地史资料,论述了北极地区在第三纪早期气候变迁对喜马拉雅-横断山地区植物区系形成的影响,并通过一些喜马拉雅-横断山地区的特征类群;杜鹃属,槭树属,柳属,桦木属和桤木属以及一些草本类群虎耳草科的落新妇族,金腰属和虎耳草属,忍冬科的莛子镳属的分布式样和起源分化的分析,说明了喜马拉雅-横断山区系中有相当一部分是这些北方起源的,北极-第三纪成分迁移是现代喜马拉雅-横断山植物区系成分的一个重要来源,并且讨论了喜马拉雅-横断山植物区系同北方植物区系可能的迁移路线,指出西南-秦岭-东北通道即西南沿四川盆地经秦岭和黄河至东北和西伯利亚和“中亚高地通道”即向西经帕米尔高原同北方交流,向东经西南-秦岭-东北通道迁移交流是喜马拉雅-横断山植物区系成分同北方交流的主要路线,由于第四纪冰期间冰期反复作用,各类成分在该地区保存,汇集,分化发展,使得该喜马拉雅-横断山地区成了北极-第三纪中心消失以后,在近代形成的温带和高山植物区系新的发展和分化中心。     

古地中海退却与喜马拉雅—横断山的隆起在中国喜马拉雅成分及高山植物区纱的形成与发展上的意义

横断山－喜马拉雅植物区系的开端是在晚白垩纪和早古近纪（早第三纪）。古植物资料在古近纪初期横断山－喜马拉雅植物区系是同古地中海沿岸一致的以照叶林为主的暖湿植物区系。古近纪后期和新近纪（新第三纪）以后古地中海气候逐步旱化。原来的暖湿植物区系在地中海地区逐步消失,而在横断山及喜马拉雅和东亚其他地区得以保存和发展,现代横断山及东喜马拉雅的亚热带森林即是其后裔。古近纪中期以后由于古地中海的逐步退却,气候变得干旱,原暖湿植物区系逐步被现代旱生的地中海植物区系所取代。新近纪以后,旱生的现代地中海植物区系由于喜马拉雅和横断山的隆起而转向适应高山环境,逐步分化形成了现代的中国－喜马拉雅成分。横断山－喜马拉雅地区硬中高山栎林的起源;铁筷子属,绿绒蒿属,芒苞草属,假百合属及马桑属的地中海,喜马拉雅－横断山间断分布的形成便是古地中海植物区系残遗的体现;黄花木属,独一味属等众多中国喜马拉雅成分就是古地中海祖先的后裔。这些代表类群的分析研究表明现代的喜马拉雅－横断山的高山植物区系以及中国－喜马拉雅成分中有相当的一部分是起源于新生代旱生的地中海植物区系。     

百合科(狭义)植物的分布区对中国植物区系研究的意义

本文对百合科(狭义)各属的地理分布作了分析,该科植物集中分布于泛北极域,属于北温带的科。该科所有的9个属,只在东亚区全部有分布,而且该区具有百合科(狭义)植物各系统演化阶段的类群,因此,东亚区是该科的多样化中心。其中百合族所包括的5个属(贝母属、百合属、大百合属、豹子花属和假百合属)集中分布于中国西南至喜马拉雅地区,其分布区均在中国-喜马拉雅地区重叠,表明中国-喜马拉雅地区是百合族的多样化中心。百合族是百合科(狭义)的核心部分。因而认为中国-喜马拉雅地区是研究百合科(狭义)植物演化的关键地区之一。从种类的统计分析表明,伊朗-土兰区分布的种类最多,说明伊朗-土兰区是该科的多度中心．文中还从一些属(贝母属、大百合属、顶冰花属和洼瓣花属)内种的分布,提出可作为划分某些植物区的依据。而且,还从假百合属的分布,阐明中国植物区系与古地中海植物区系的亲缘。     

The SRS 3D module: integrating structures, sequences and features

In this paper we present SRS 3D, a new service that allows users to easily and rapidly find all related structures for a given target sequence; structures can then be viewed together with sequences, alignments and sequence features (currently from UniProt, InterPro and PDB). Extensive user feedback confirms that SRS 3D is intuitive and useful especially for those not expert in structures. AVAILABILITY: An SRS 3D server is provided at http://srs3d.ebi.ac.uk/.     

FebRNA: An automated fragment-ensemble-based model for building RNA 3D structures

Knowledge of RNA three-dimensional (3D) structures is critical to understanding the important biological functions of RNAs. Although various structure prediction models have been developed, the high-accuracy predictions of RNA 3D structures are still limited to the RNAs with short lengths or with simple topology. In this work, we proposed a new model, namely FebRNA, for building RNA 3D structures through fragment assembly based on coarse-grained (CG) fragment ensembles. Specifically, FebRNA is composed of four processes: establishing the library of different types of non-redundant CG fragment ensembles regardless of the sequences, building CG 3D structure ensemble through fragment assembly, identifying top-scored CG structures through a specific CG scoring function, and rebuilding the all-atom structures from the top-scored CG ones. Extensive examination against different types of RNA structures indicates that FebRNA consistently gives the reliable predictions on RNA 3D structures, including pseudoknots, three-way junctions, four-way and five-way junctions, and RNAs in the RNA-Puzzles. FebRNA is available on the Web site: https://github.com/Tan-group/FebRNA.     

Indicanines B and C, two isoflavonoid derivatives from the root bark of Erythrina indica

In addition to two known compounds, 5,4'-di-O-methylalpinumisoflavone and cajanin, a new 3-phenylcoumarin metabolite, named indicanine B, and a new isoflavone derivative, named indicanine C, were isolated from the root bark of Erythrina indica. By means of spectroscopic analysis, the structures of the new compounds were characterized as 4-hydroxy-3-(4'-hydroxyphenyl)-5-methoxy-2",2"-dimethylpyrano [5",6":6,7] coumarin and 4'-hydroxy-5-methoxy-2",2"-dimethylpyrano [5",6":6,7] isoflavone, respectively. The 13C-NMR data of cajanin and the in vitro antimicrobial spectrum and potencies of the isolated compounds are also reported.     

Two New Saponins from Lysimachia capillipes Hemsl.

To investigate the saponins from whole plants of Lysimachia capillipes Hemsl., two new saponins, named capilliposide E (1) and capilliposide F (2), were isolated. The structures of the new sa ponins were elucidated as 3 β, 22α-dihydroxy- 16α-acetat-28→ 13 -lactone-oleanane-3 -O- [β-D-glucopyranosyl(1→2)-α-L-arabinpyranoyl]-22-O-β-D-glucopyranoside (1) and 3 β, 22α-dihydroxy- 16α-acetat-28→ 13-1actone-oleanane-3-O- { [β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)]-α-L-arabinpyranoyl }-22-O-βD-glucopyranoside (2). The structures of these compounds were determined by 1D- and 2D-NMR, MS techniques, and chemical methods.     

Diterpenes from Palafoxia texana

The investigation of Palafoxia texana afforded in addition to the known compound jesromotetrol two new rosene derivatives: 3β-acetoxy-jesromotetrol and 3β,19-diacetoxy-jesromotetrol. The structures were determined by spectroscopic methods and chemical transformations.     

Elaeodendrol and elaeodendradiol,new nor-triterpenes from Elaeodendron glaucum

The isolation of six known and two new D:A-friedooleananes is reported from the bark of Elaeodendron glaucum. The structures of the new nor-triterpenes, elaeodendrol and elaeodendradiol, were established respectively as 17β- hydroxy-28-norfriedelan-3-one and l7β,25-dihydroxy-28-norfriedelan-3-one by a study of the methyl chemical shifts in their ¹H NMR spectra.     

Terpenoids from Tripterygium wilfordii var. regelii

The methanol extract of dried stem barks of Tripterygium wilfordii Hook fil. var regelii afforded two new triterpenes: 22-hydroxy-3, 19,24-trinor-D:A-friedoolenane-1(10), 5, 7-triene-2-oic acid methyl ester, named regelone, and 3-methyl-23-ol-oxotingenol; a new diterpene—8β, 19-dihydroxy-3-oxopimar- 15-ene; and three known triterpenes-3-methyl-22-β, 23-diol-6-oxotingenol, tingenin B and cangoronin. Their structures were established on the basis of chemical and spectroscopic studies. ©1997 Elsevier Science Ltd. All rights reserved     

UMARS: Un-MAppable Reads Solution

Background

Few high-resolution structures of integral membranes proteins are available, as crystallization of such proteins needs yet to overcome too many technical limitations. Nevertheless, prediction of their transmembrane (TM) structure by bioinformatics tools provides interesting insights on the topology of these proteins.

Methods

We describe here how to extract new information from the analysis of hydrophobicity variations or hydrophobic pulses (HPulses) in the sequence of integral membrane proteins using the Hydrophobic Pulse Predictor, a new tool we developed for this purpose. To analyze the primary sequence of 70 integral membrane proteins we defined two levels of analysis: G1-HPulses for sliding windows of n = 2 to 6 and G2-HPulses for sliding windows of n = 12 to 16.

Results

The G2-HPulse analysis of 541 transmembrane helices allowed the definition of the new concept of transmembrane unit (TMU) that groups together transmembrane helices and segments with potential adjacent structures. In addition, the G1-HPulse analysis identified helix irregularities that corresponded to kinks, partial helices or unannotated structural events. These irregularities could represent key dynamic elements that are alternatively activated depending on the channel status as illustrated by the crystal structures of the lactose permease in different conformations.

Conclusions

Our results open a new way in the understanding of transmembrane secondary structures: hydrophobicity through hydrophobic pulses strongly impacts on such embedded structures and is not confined to define the transmembrane status of amino acids.     

Diterpenes from the leaves of Croton zambesicus

Two new trachylobane- and one isopimarane-type diterpenoids: ent-18-hydroxy-trachyloban-3-one; ent-trachyloban-3-one; isopimara-7,15-dien-3beta-ol, were isolated from the leaves of Croton zambesicus, together with trans-phytol, beta-sitosterol, alpha-amyrin and stigmasterol. The structures were determined by extensive NMR techniques and X-ray analysis. The cytotoxicity of these compounds has been evaluated on cancer and non-cancer cell-lines.     

Three biflavonoids from Daphne odora

Three new biflavonoids, daphnodorins G-I, were isolated from the roots of Daphne odora and their structures established from spectral and chemical means. These are two C-7/C-2″, C-8/C-3″ biflavonoids (upper half: apigenin, lower half: afzelechin), daphnodorins G and H and a spirobiflavonoid, daphnodorin I.