胡椒科的花粉形态及其分类学意义

胡椒科的某些属之间,花粉形态表现出一定的差异。齐头绒属花粉粒表面粒为平滑,但有小穿孔,略显粗糙。胡椒属的花粉粒表面有不规则的瘤状纹饰,纹饰较为平滑。Ｌｅｐｉａｎｔｈｅｓ（Ｐｏｔｈｏｍｏｒｐｈｅ）的花粉粒表面瘤状纹饰不显著。     

东北槭属的种子表皮雕纹及其在分类上的意义

借助于扫描电子显微镜,对我国东北地区槭属（Ａｃｅ）的１１种变种的种皮雕纹进行了扫描观察,并拍制了电镜照片。从种皮的雕纹类型看,槭树属的种皮可以概括为四种类型：（１）嵌合型;（２）穴状条纹型;（３）条纹型;（４）网格型;雕纹的形态也支持了色木槭和元宝械作为两个独立种的处理意见;以及小果紫花槭作为紫花槭（Ａｃｅｒｐｓｅｕｄｏ－ｓｉｅｂｏｌｉｄｉａｎｕｍ（Ｐａｘ．）Ｋｏｍ）的种下等级变种（ｖａｒ．ｋｏｒ     

Modelling publication bias and p-hacking

Publication bias and p-hacking are two well-known phenomena that strongly affect the scientific literature and cause severe problems in meta-analyses. Due to these phenomena, the assumptions of meta-analyses are seriously violated and the results of the studies cannot be trusted. While publication bias is very often captured well by the weighting function selection model, p-hacking is much harder to model and no definitive solution has been found yet. In this paper, we advocate the selection model approach to model publication bias and propose a mixture model for p-hacking. We derive some properties for these models, and we compare them formally and through simulations. Finally, two real data examples are used to show how the models work in practice.     

History of the montane forests of the northern Andes

From the vascular plant genera of the tropical Andean montane forests about 65% have a tropical-neotropical, 15% tropical-Andean, 5% amphi-pacific (Malayo-American), 5% Austral-antarctic and 10% Holarctic distribution. The explosive evolution of Andean centred taxa probably started in the lower Tertiary from tropical Gondwana stock, when in the area of the present day Andes, locally there may have been hills up to 1 000m. With the final upheaval between the Late Miocene and Late Pliocene, extensive areas with a montane climate were created and populated from the low mountain flora by evolutionary radiation. Taxa of Austral-antarctic origin migrated along the Andean chain to the tropics. At the same time the formation of the Panama isthmus connected N. and S. America, and enabled many plants to enter the tropical Andes from the north. First to cross were tropical to subtropical and warm-temperate species from the Tertiary Laurasian flora that had migrated southward during the period of Miocene cooling, taking refuge in the montane tropics. Because the same happened in SE. Asia there is a good number of amphi-pacific taxa known as fossils from Tertiary Laurasia but largely extinct in the present-day Holarctic (e.g.,Trigonobalanus). Later to cross were cool-temperate to cold elements that still exist in the Holarctic (e.g.,Alnus andQuercus).     

Leaf Venation and Its Systematic Significance in Sapindaceae of China

Leaf venation of 27 species representing 25 genera of Sapindaceae (sstr.) of China was investigated for the first time. The pinnate venation pattern in most species is either camptodromous, or craspedodromous. Three types of leaf blade margin were observed, ie., entire, toothed and partite. The secondary veins are branched or unbranched. Most species have intersecondary veins. The tertiary veins of most species are reticulate and percurrent. The areoles are regular or irregular. Veinlets are simple, branched or absent. The delimitations of Xanthoceroideae and Lepisanthes sensu lato are supported by leaf venation characters. The close relationships among Dimocarpus, Litchi and Nephelium are supported by the evidence from leaf venation. A key to the species of Sapinaceae based on leaf venation characters is presented.     

Phytogeographical relations of the Andean dry valleys of Bolivia

Aim The objective of this study is to examine the phytogeographical affinities of the Andean dry valleys of Bolivia in order to contribute to a better understanding of the Andean dry flora's distribution, origin and diversity. Particular emphasis is given to the analysis of the floristic connections of this flora with more austral parts of South America. Location The dry valleys of Bolivia are located in the Andes of the southern half of the country, at elevations between 1300 and 3200 m. Methods An extensive floristic list compiled by the author to evaluate plant diversity in these Andean regions was used as the base for this study. To accomplish this, all recorded genera and species were assigned, respectively, to 11 and 12 phytogeographical elements established previously by the author. Two phytogeographical spectra were thus obtained and analysed. Results At the genus level, the Andean dry valleys of Bolivia are clearly dominated by genera that have widespread distributions (cosmoplitan and subtropical genera). Many of these reached the Andes from the lowland region of the Chaco. At species level, Andean elements constitute more than 60% of the species total, most of which are restricted to the central‐southern Andes. This suggests that Chaco‐related and Andean genera had considerable levels of speciation in these valleys. Many genera and more than half the species have their northernmost distribution in the dry valleys of Bolivia, thereby underlining strong relationships with central‐southern South America (mainly Argentina, Paraguay and southern Brazil). The data supports the belief of the existence, in central‐southern Peru, of a floristic disjunction in dry to arid environments that separates a tropical dry flora north of this limit from a dry subtropical/warm temperate flora south of it. Main conclusions The Andean dry valleys of Bolivia are diverse plant communities with high levels of endemism (c. 18% of the species). The species of this region are more related to those present in central‐southern South America than to the flora of northern South America that ranges southwards to Peru. Many of the species have restricted distributions in the dry Andes of Bolivia and Argentina, and many genera of these dry valleys have their northernmost distribution in Bolivia/southern Peru, too. The data point to high levels of speciation also in the central Andes.     

山矾科中原氏山矾复合体的叶形态特征及分类意义

该研究在形态学观察以及统计学分析的基础上,深入研究了山矾科中原氏山矾复合体的叶片形态学结构。结果表明:叶片质地在整个复合体中可分为革质、纸质2种类型,叶片大小变异幅度较大,除中原氏山矾(Symplocos kawakamii)、棱角山矾(S.tetragona)、蒙自山矾(S.henryi)均与其他种差异显著外,其余种均属于连续过度,叶片分形可以初步区分该复合体植物。该研究结果为中原氏山矾复合体的进一步研究提供了依据,对复合体的分类处理具有一定的分类学意义。     

第四军医大学唐都医院实验外科

目的：探讨易洛魁家族同源盒基因IRX1（Iroquois homeobox gene）在胶质瘤中的表达及其临床意义。方法：收集4 位胶质瘤 患者的胶质瘤组织和癌旁/ 正常组织各1 例,收集54 例胶质瘤组织（WHO I级5例,II 级16 例,III 级14 例,IV 级19 例）,采用 PCR方法检测IRX1基因在胶质瘤细胞（U87、U373、LN229 和T98G）中的表达,Western Blot 检测4 组同一患者来源的胶质瘤组 织中IRX1 的表达,免疫组织化学法（IHC）检测IRX1 在胶质瘤组织中的表达及临床特征。结果：PCR 结果表明以正常脑组织为对 照,IRX1 基因在多种胶质瘤细胞中均有表达（P＜0.05）;Western Blot 结果显示IRX1 蛋白在胶质瘤组织中的表达显著高于癌旁组 织或正常组织（P＜0.05）;IHC结果显示IRX1蛋白在良性胶质瘤组织中主要定位于胞浆,而在恶性胶质瘤组织中定位于细胞核, 且其表达量与胶质瘤的恶性程度相关,恶性程度越高,其在细胞核中的表达量越高（P＜0.05）。结论：IRX1可能参与调控恶性胶质 瘤的发生发展过程,IRX1 的表达与胶质瘤的恶性程度有关,暗示了IRX1 可作为判断胶质瘤预后以及肿瘤靶向分子治疗的指标。     

细菌胞际电子转移及其生态生理学意义研究进展

胞际电子转移是指细胞内电子以间接或直接的方式传递到细胞外,最终到达细胞周围电子受体的过程.胞际电子转移普遍存在于自然界,尤其存在于电子受体相对匮乏的环境中.胞际电子转移可分为间接和直接胞际电子转移.间接胞际电子转移(胞际基质转移)是主要借助氢、甲酸以及其他代谢产物的电子传递;而直接胞际电子转移则由胞内电子转移偶联胞外电子传递实现.胞际电子转移促进了细胞的基质代谢活性,拓展了细胞的作用空间,具有重要的生理意义.胞际电子转移产生了电流,实现了菌间能源共享,驱动了胞外物质(如重金属、腐殖质)转化,具体重大的生态意义.本文总结相关文献,对细菌胞际电子转移的过程、特点、机理及其生态生理学意义作了系统的分析和探讨.