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。     

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。     

海南岛新生代种子植物区系科的多样性分析

根据化石及现代植物资料,海南岛第三纪种子植物有53科,其中古近纪已出现48科,新近纪降至25科,第四纪晚期有89科,现代增加至233科.区系地理成分分析结果表明,海南岛古近纪时,泛热带科占当时科总数的45.8%,热带-亚热带科占8.3%,亚热带-温带科占31.3%,其中出现了很多海南岛现代植物区系的表征科,如冬青科、壳斗科、金缕梅科、樟科、桃金娘科、罗汉松科、棕榈科、红树科、梧桐科和松科等,基本形成了现代海南岛植物区系的雏形.新近纪时由于全球气候变冷,本区植物区系组成大幅度减少,热带性质也明显减弱,其中泛热带分布的科仅占当时海南岛植物区系全部科的32.0%,热带-亚热带分布的科占12.0%,而亚热带-温带分布的科所占比例有所升高,达36.0%.第四纪晚期至现代,随着气候逐渐回暖,本区植物区系的热带性质逐渐加强.第四纪晚期泛热带科占当时科总数的49.4%,热带-亚热带科占12.4%,亚热带-温带科占19.1%,区系特征逐渐接近现代.现代海南种子植物区系中,泛热带分布科占科总数48.1%,热带-亚热带科占18.9%,亚热带-温带科占15.9%.总体上,海南岛第三纪早期的古近纪、第四纪晚期一直到现代均以泛热带分布的科占优势,而第三纪晚期的新近纪本区植物区系的热带性质较弱.整体上反映出海南岛新生代种子植物区系的演变特征与古近纪以来全球气候的变化有密切的联系.     

喜马拉雅东部雅鲁藏布江大峡弯河谷地区植物区系的特点及来源

喜马拉雅东部雅鲁藏布江大峡弯河谷地区植物区系多样性的组成十分丰富,共有种子植物１８０科,６４３属,１４１０种,并有明显的热带向温带过渡的特点,是热带和温带植物区系的两大区系结,它是第三纪以后才发展起来的年轻区系,归根结蒂是源出于古老的东亚植物区系和印度马来植物区系。     

中国西南干旱河谷植被的区系地理成分与空间分异

根据对云南、四川、甘肃三省九条主要河流干旱河谷的植物群落调查数据, 对我国西南干旱河谷维管束植物区系的科、属分布区类型进行划分, 并分析其地理分布格局。结果表明: (1)西南干旱河谷区的植物区系地理成分复杂, 联系广泛, 共包含11个科级和15个属级分布区类型; 总体上, 科、属两级热带/温带成分比例分别为3.06和1.77, 显示了强烈的热带区系亲缘及温带区系的后期影响; 与地中海-西亚至中亚植物区系存在一定联系; 其东亚成分和中国特有成分比例低于亚热带区系平均水平, 且中国-喜马拉雅成分比例高于中国-日本成分。(2)从西南向东北方向, 植物区系的热带性质逐渐减弱, 温带性质逐渐增强; 科、属水平区系成分与古地中海-中亚区系的相似性逐渐增强; 东亚和中国特有成分比例增加; 南盘江与元江的干旱河谷植物区系之间存在中国-日本和中国-喜马拉雅成分的分界线。(3)根据干旱河谷植物属区系成分的比例构成将怒江、澜沧江和元江与其他流域分开, 显示了长江溯源侵蚀和水系合并对西南诸河流植物区系发育的影响。     

中国-喜马拉雅地区硬叶栎林的特点与分类

本文对中国—喜马拉雅地区的硬叶栎林,研究了它的主要特点和分类系统。根据硬叶栎林地区各气象站气候图解的特点(“A”字形),认为硬叶栎林是夏雨区的硬叶林,它不同于世界上冬南区的(“U”字形气候图解)硬叶林。 根据硬叶栎林的植物区系和生态环境,它不属于亚热带的照叶林和地中海型的硬叶林,而是中国—喜马拉雅地区特有的夏雨硬叶林,在中国西部高山地区的阳坡上常为顶极群落。根据硬叶栎林的优势树种和海拔、气候、土壤及伴生树种,分为10个群系和两个群系组。     

青藏高原和喜马拉雅地区锦鸡儿属植物的地理分布

锦鸡儿属Caragana是一个典型的温带亚洲分布属。本属在青藏高原和喜马拉雅约有24种1变种,约占整个属的1／3。这些种类几乎全部处于演化高级阶段,且既有叶轴宿存类群,也有假掌状叶类群。反映出种的分化很活跃,在横断山地区形成本属的分布中心、分化中心。本区内绝大多数种类是特有分布。替代现象主要受气候、植被变化作用,沿横断山和喜马拉雅分布的长齿系Ser. Bracteolatae Kom．是一个典型的替代分布类群。锦鸡儿属植物生态适应性很强,可在其生长的灌丛中形成优势种。 寒化和旱化现象十分突出,它们有一系列森林种、草原种和荒漠种及相关的形态变异。用锦鸡儿属植物进行青藏高原和喜马拉雅区域内的分布区关系分析及最小生成树MST和特有性简约性分析(PAE),表明横断山地区特别是其北部是本属植物的一个地理结点。以此沿横断山向北部唐古特和西部藏东南适应性辐射。横断山和西喜马拉雅联系微弱,看不出植物长距离扩散的踪迹,大多是由于生态因子限制而产生的隔离。虽然本区不可能是锦鸡儿属的起源地,然而,通过本区与邻近地区的地理联系,可推测它们在我国适应性辐射方向是从东北向西南。结合豆科蝶形花亚科其它属化石记录及其分布区局限在温带亚洲等现象,认为锦鸡儿植物是一组特化、晚近衍生的类群,起源于北方东西伯利亚晚第三纪中新世后期至上新世。     

大理苍山种子植物区系的研究

通过对苍山种子植物164科,852属,2 503种,45亚种,194变种在各个层次不同角度上的分析,探讨了本区种子植物区系的性质、地位、起源及演化。区系分析表明:大理苍山种子植物区系在我国区系区划上属于东亚植物区,中国-喜马拉雅森林植物亚区,横断山脉地区,三江峡谷亚地区;其区系具有鲜明的温带性质;现代苍山植物区系是在印度板块与欧亚板块碰撞,古地中海退却和喜马拉雅隆升等地质事件背景下,由古地中海成分、北极—第三纪成分及古南大陆成分融汇发展而来;苍山的特有现象较为显著,新老皆备,且以新特有成分为主,它既是古特有成分的避难所,也是新特有成分发展的温床;苍山在植物分布上是呼应东、西、南、北的纽带,同时又是很多成分分布的边界,是重要的区系节。     

喜马拉雅地区藤本植物多样性及其地理格局

喜马拉雅山地是生物地理学研究的热点地区之一。本文对喜马拉雅地区的藤本植物多样性及其与毗邻地区的联系进行了统计分析, 并对该地区与印度河-恒河平原地区藤本植物多样性的地理格局及其成因进行了研究。结果显示: (1)喜马拉雅地区总计有1,083种藤本植物, 分属72科309属; 其中木质藤本725种, 草质藤本358种; 攀援方式主要为缠绕攀援(51.3%)。(2)该区域的藤本植物组成受相邻区域植物区系的显著影响, 其1,083种藤本植物中有74.1% (802种)在东南亚地区有分布, 50.6% (548种)在南亚有分布, 48.9% (530种)在中国西南地区有分布。本区藤本植物缺乏特有性, 仅125种(11.5%)为本区所特有, 没有特有含藤属。(3)藤本植物多样性及其在植物区系中的比例均自东向西逐渐降低; 木质藤本比例和缠绕攀援藤本比例均自东向西略呈上升趋势; 大多数含藤属的藤本多样性由东往西递减, 仅极少数含藤属由东往西逐渐增加, 如野豌豆属(Vicia)和菟丝子属(Cuscuta)。(4)藤本植物多样性在喜马拉雅和印度河-恒河平原地区呈现出自东向西递减的相似格局, 由东往西方向上含藤属递减率分别为8.4属/100 km和6.3属/100 km, 但喜马拉雅地区藤本植物多样性更高。喜马拉雅和印度河-恒河平原地区均有分布的272个含藤属中有196属在中亚及伊朗高原不再有分布, 其中31.1% (61属)在喜马拉雅地区的分布显著更偏西, 仅4.1% (8属)在印度河-恒河平原的分布显著更偏西。综合分析表明, 喜马拉雅地区藤本植物的多样性及其地理格局的特点与其特殊的地理位置、气候条件和生境的梯度变化以及毗邻地区植物区系的多元化有关; 水分条件的东西向梯度变化可能是藤本植物在喜马拉雅和印度河-恒河平原地区形成相似格局的主要原因。     

喜马拉雅山区新生代植物群与聚煤环境

新生代,特别是第三纪是地史上最晚的重要聚煤时期,煤的聚集是同植物的多寡、地质构造、地理环境和气候条件的发展变化紧密相关的。植物是成煤的物质基础,它受气候和地理环境的制约;而构造运动使地壳发生变化造成有利于植物残体堆积的地形,为聚煤作用提供良好的条件。本文试图就上述4种因素,特别着重于植物和气候因素简要地探讨喜马拉雅和横断山地区煤田的形成和聚煤环境。一、地质简况早在中生代时,印度洋已经扩张,特提斯洋壳向欧亚大陆俯冲,同时印度板块向北漂移,特     

Serology and systematics of the Ebenales and the Theales

The systematic position ofthe Ebenaceae, Sapotaceae, Styracaceae, Ochnaceae, Stachyuraceae, Dipterocarpaceae, Clusiaceae and Hypericaceae has been investigated using serological comparisons of sets of antigenic determinants. The results show that the Sytracaceae and Sapotaceae are undoubtedly more closely associated with the Actinidiaeceae and Theaceae, respectively, than with each other. We found no corresponding determinants betnween antigen systems from the Ebenaceae and systems from any other family whose relations to this family have been proposed. As discovered previously, investigations of antigen systems from the Ochnaceae, Dipterocarpaceae, Stachyuraceae, Clusiaceae and Hypericaceae are against the idea of a natural order “Theales” in which these families, or at least some of them, are combined with the Theaceae and Actinidiaceae. This paper completes our previous investigations which largely support a superorder Ericanae sensu Ehrendorfer and Takhtajan. We propose to include the Actinidiaceae and Theaceae in this superorder, assigning them a central position laong with the Sapotaceae and Sytracaeae on one side and the Primulales and Ericales on the other. Another most interesting finding is that there are corresponding determinants between antigen systems from the members of the Ericanae and representatives of the Polemoniaceae and Loasaceae.     

On the structure and dynamics of the complex of the nucleosome and the linker histone

Several different models of the linker histone (LH)–nucleosome complex have been proposed, but none of them has unambiguously revealed the position and binding sites of the LH on the nucleosome. Using Brownian dynamics-based docking together with normal mode analysis of the nucleosome to account for the flexibility of two flanking 10 bp long linker DNAs (L-DNA), we identified binding modes of the H5-LH globular domain (GH5) to the nucleosome. For a wide range of nucleosomal conformations with the L-DNA ends less than 65 Å apart, one dominant binding mode was identified for GH5 and found to be consistent with fluorescence recovery after photobleaching (FRAP) experiments. GH5 binds asymmetrically with respect to the nucleosomal dyad axis, fitting between the nucleosomal DNA and one of the L-DNAs. For greater distances between L-DNA ends, docking of GH5 to the L-DNA that is more restrained and less open becomes favored. These results suggest a selection mechanism by which GH5 preferentially binds one of the L-DNAs and thereby affects DNA dynamics and accessibility and contributes to formation of a particular chromatin fiber structure. The two binding modes identified would, respectively, favor a tight zigzag chromatin structure or a loose solenoid chromatin fiber.     

Epigenetics and aging: the targets and the marks

'Aging epigenetics' is an emerging field that promises exciting revelations in the near future. Here we focus on the functional and biological significance of the epigenetic alterations that accumulate during aging and are important in tumorigenesis. Paradigmatic examples are provided by the global loss of DNA methylation in aging and cancer and by the promoter hypermethylation of genes with a dual role in tumor suppression and progeria, such as the Werner syndrome (WRN) and lamin A/C genes. Another twist is provided by sirtuins, a family of NAD-dependent deacetylases that act on Lys16 of histone H4, which are emerging as a link between cellular transformation and lifespan.     

Biophysics and Structure of the Patch and the Gigaseal

Interpreting channel behavior in patches requires an understanding of patch structure and dynamics, especially in studies of mechanosensitive channels. High resolution optical studies show that patch formation occurs via blebbing that disrupts normal membrane structure and redistributes in situ components including ion channels. There is a 1-2 μm region of the seal below the patch where proteins are excluded and this may consist of extracted lipids that form the gigaseal. Patch domes often have complex geometries with inhomogeneous stresses due to the membrane-glass adhesion energy (E_a), cytoskeletal forces, and possible lipid subdomains. The resting tension in the patch dome ranges from 1-4 mN/m, a significant fraction of the lytic tension of a bilayer (∼10 mN/m). Thus, all patch experiments are conducted under substantial, and uneven, resting tension that may alter the kinetics of many channels. E_a seems dominated by van der Waals attraction overlaid with a normally repulsive Coulombic force. High ionic strength pipette saline increased E_a and, surprisingly, increased cytoskeletal rigidity in cell-attached patches. Low pH pipette saline also increased E_a and reduced the seal selectivity for cations, presumably by neutralizing the membrane surface charge. The seal is a negatively charged, cation selective, space with a resistance of ∼7 gigohm/μm in 100 mM KCl, and the high resistivity of the space may result from the presence of high viscosity glycoproteins. Patches creep up the pipette over time with voltage independent and voltage dependent components. Voltage-independent creep is expected from the capillary attraction of E_a and the flow of fresh lipids from the cell. Voltage-dependent creep seems to arise from electroosmosis in the seal. Neutralization of negative charges on the seal membrane with low pH decreased the creep rate and reversed the direction of creep at positive pipette potentials.     

Metamorphosis in the Cirripedia Rhizocephala and the homology of the kentrogon and trichogon

The Rhizocephala are considered to be monophyletic due to several synapomorphies in the ontogeny of the cndoparasitic phase. The various types of metamorphosis described in the Rhizocephala are discussed and compared to metamorphosis in the Cirripedia Thoracica and Acrothoracica. In males and females of the suborder Kentrogonida. the cyprid settles and metamorphoses into a new instar, in males the trichogen and in females the infective kentrogon. The kentrogon goes through yet another. incomplete moult associated with the development of the stylet. Within the three kentrogonidan families. the Iernaeodiscid-peltogastrid type of kentrogon differs from the sacculinid type in the mode of attachment to the host. in the complexity of internal anatomy. in the position and penetration of the stylet, and in whether or not the cyprid carapace must be shed prior to penetration of the stylet. In the Akentrogonida metamorphosis never results in a new instar. Where observed (Clistosaccidae and Thompsoniidae). both male and female cyprids settle and penetrate into their substrate (female parasite or new host) with one of the antennules. Using the antennule as a syringe. male cyprids inject spermatogonia while female cyprids injects embryonic cells developing into an endoparasite. By comparison with metamorphosis in the Cirripedia Thoracica and Acrothoracica it is concluded that the presence of a metamorphic moult leading to a post-cyprid instar is plesiomorphic and that the trichogon and kentrogon are homologous with the first metamorphosed juvenile in these outgroups. The abbreviated ontogeny in the Akentrogonida without metamorphic moult and post-cyprid larval instars is considered apomorphic. This contradicts the long-held supposition that the Akentrogonida are the most‘primitive’Rhizocephala and dovetails with new information that this suborder contains many advanced traits. Within the Kentrogonida. the lernacodiseid-peltogastrid type of kentrogon is considered more plesiomorphic than the sacculinid type, which resembles the clistosaccidthompsoniid type in having the antennules involved in the penetration process. The homologization of the kentrogon with a juvenile barnacle indicates that presence of a kentrogon is plesiomorphic within the Rhizocephala and that the Kentrogonida is paraphyletic.     

Phymosomatoid echinoids from the campanian and the maastrichtian of Belgium and the Netherlands

Phymosomatoid echinoids from the Campanian and the Maastrichtian of Belgium and the Netherlands are systematically revised. Ten species, belonging to four genera are identified and described. One new species is introduced:Gauthieria?mosae sp. nov.     

The Choroid Plexuses and the Barriers Between the Blood and the Cerebrospinal Fluid

1. The fluid homeostasis of the brain depends both on the endothelial blood–brain barrier and on the epithelial blood–cerebrospinal fluid (CSF) barrier located at the choroid plexuses and the outer arachnoid membrane.2. The brain has two fluid environments: the brain interstitial fluid, which surrounds the neurons and glia, and the CSF, which fills the ventricles and external surfaces of the central nervous system.3. CSF acts as a fluid cushion for the brain and as a drainage route for the waste products of cerebral metabolism.4. Recent findings suggest that CSF may also act as a third circulation conveying substances secreted into the CSF rapidly to many brain regions.