4种红豆杉属植物遗传多样性和遗传关系的RAPD分析

采用RAPD标记研究了分属于4种红豆杉属(Taxus Linn.)植物的68个单株的遗传多样性,并采用UPGMA方法分析68个单株的遗传关系.结果表明:12条RAPD引物共扩增出109条带,其中多态性条带108条,多态性条带百分率为99.1％;平均每条引物扩增出9.1条带.南方红豆杉[T.wallichiana var.mairei (Lemée et Lévl)L.K.Fu et Nan Li.]种内的多态性条带百分率和观察等位基因数均最高;欧洲红豆杉(T.baccata Linn.)种内的有效等位基因数、Nei's基因多样度和Shannon's信息指数均最高;须弥红豆杉(T.wallichiana Zucc.)种内的各项遗传多样性指数均最低.供试4种植物的种内遗传多样度、种间遗传多样度、基因流和种间遗传分化系数分别为0.1745、0.358 6、0.401 7和0.554 5,表明55.45％的遗传变异发生在种间.南方红豆杉和须弥红豆杉遗传距离最近;曼地亚红豆杉(Taxus×media Rehd.)和须弥红豆杉的遗传距离最远.通过聚类分析可将68个单株分为3组,欧洲红豆杉的18个单株和曼地亚红豆杉的18个单株分别各自聚为1组;须弥红豆杉的16个单株和南方红豆杉的16个单株聚为1组,其中须弥红豆杉的16个单株和南方红豆杉的16个单株又各自聚为1个亚组,且南方红豆杉的雌、雄单株也分别聚在同一分支上,表明须弥红豆杉和南方红豆杉遗传关系较近,而欧洲红豆杉与其他3种植物的遗传关系较远.     

The influence of temperature on the dynamics of protein precrystallization clusters,studied by photon correlation spectroscopy

Hen-egg white lysozyme was used for studying the influence of temperature on crystallization. The reaction was initiated at variable temperatures, covering the range between 5–50 °C, and was monitored with photon correlation spectroscopy. When aggregation was induced by addition of NaCl, the clusters formed exhibited diffusion limited aggregation behavior and crystals appeared in less than two days. In contrast, (NH₄)₂SO₄ induced aggregation took place mostly in the cross-over regime. In this case, solutions either remained transparent and void of crystals or formed gels within a few weeks. In both cases the kinetics could be dynamically scaled into master curves indicating that the precrystallization formed aggregates are fractals resulting from different collision processes.     

利用秆维管束进行中国散生竹类的聚类分析

本文是应用模糊聚类分析方法研究中国散生竹类分类的一次尝试。分类特征采用了竹秆上、中、下三段各类型维管束数,方法上使用了模糊(Fuzzy)直接聚类分析进行综合分析。经电子计算机运算后,不仅取得了与传统分类基本一致的分类结果,同时也表明这种方法较之其它一些植物数量分类方法简便易行,此外还讨论了一些中国散生竹类分类上的问题。     

The MOSIX Direct File System Access Method for Supporting Scalable Cluster File Systems

MOSIX is a cluster management system that supports preemptive process migration. This paper presents the MOSIX Direct File System Access (DFSA), a provision that can improve the performance of cluster file systems by allowing a migrated process to directly access files in its current location. This capability, when combined with an appropriate file system, could substantially increase the I/O performance and reduce the network congestion by migrating an I/O intensive process to a file server rather than the traditional way of bringing the file's data to the process. DFSA is suitable for clusters that manage a pool of shared disks among multiple machines. With DFSA, it is possible to migrate parallel processes from a client node to file servers for parallel access to different files. Any consistent file system can be adjusted to work with DFSA. To test its performance, we developed the MOSIX File-System (MFS) which allows consistent parallel operations on different files. The paper describes DFSA and presents the performance of MFS with and without DFSA.     

长江春大豆核心种质构建及分析

利用长江春大豆初选核心种质SSR(simple sequence repeat）标记和农艺性状表型等基础数据,对用不同个体取样方法以及不同数据类型建立的核心种质进行评价,目的是确定中国大豆（Glycine max）核心种质的最佳取样策略提供依据,结果表明,根据SSR分子数据聚类,采用类内随机取样,类内以遗传相似性系数取样以及仅依据遗传相似性系数取样都可用于大豆核心种质构建,但是综合不同评价参数发现,以类内随机取样最佳,类内按遗传相似性系数取样次之,单独以遗传相似性系数取样较差。分析不同SSR等位变异保留比例的遗传多样性指数发现,当保留90%和80%的SSR等位变异时,核心种质具有更高的遗传多样性,由于与SSR分子数据种质遗传关系评价的不一致性,农艺性状等基础数据虽然可用来构建核心种质,但其SSR分子水平代表性相对较低,本研究结果还表明,用不同方法或同一方法不同重复次数取样建立的核心种质具有异质性,且这种异质性随核心种质取样比例的降低而增大,因此,虽然可依据不同数据类型确定相应的方法建立核心种质,但综合表型和分子数据建立的核心种质更具有代表性。     

云南省6个松墨天牛种群形态差异分析

对云南省松墨天牛Monochamus alternatus Hope 6个地理种群159个个体体长、前胸背板纵长、前胸背板横宽值及前胸背板斑纹进行了差异系数计算、聚类分析及判别分析.各松墨天牛种群间的差异系数均小于1.28;聚类分析表明,畹町种群形态与其他5个种群差异较大;基于4个形态特征建立的判别函数可以将畹町种群与云南其他种群区别开来.畹町种群与其他松墨天牛种群的形态差异可能由于其遗传差异造成.     

Synthesis of closo-Dodecaboryl Lipids and their Liposomal Formation for Boron Neutron Capture Therapy

High accumulation and selective delivery of boron into tumor tissues are the most important requirements to achieve efficient neutron capture therapy of cancers. We focused on liposomal boron delivery system to achieve a large amount of boron delivery to tumor. We succeeded in the synthesis of the double-tailed boron cluster lipids 4a–c and 5a–c, which has a B₁₂H₁₁S-moiety as a hydrophilic function, by S-alkylation of B₁₂H₁₁SH with bromoacetyl and chloroacetocarbamate derivatives of diacylglycerols. Size distribution of liposomes prepared from the boron cluster lipid 4b, dimyristoylphosphatidylcholine, polyethyleneglycol-conjugated distearoylphosphatidylethanolamine, and cholesterol was determined as 100 nm in diameter by an electrophoretic light scattering spectrophotometer. Calcein-encapsulation experiments revealed that these boronated liposomes are stable at 37 °C in fetal bovine serum solution for 24 h.     

高温胁迫下五种杜鹃花属植物的生理变化及其耐热性比较

高温是制约分布于较高海拔地区杜鹃花迁地保育与园林应用的重要因子.为探讨杜鹃花属植物的 高温致伤机理,该实验以隶属不同亚属的白花杜鹃、羊踯躅、毛棉杜鹃、红滩杜鹃及红棕杜鹃4年生实生苗为 材料,通过人工气候箱的盆栽实验,研究了30℃、38℃高温胁迫下其叶片生理生化指标的变化,并利用隶属 函数法及系统聚类分析法对其种间...     

Fire frequency and time‐since‐fire effects on the open‐forest and woodland flora of Girraween National Park,south‐east Queensland,Australia

Abstract The effects of recent fire frequency and time‐since‐fire on plant community composition and species abundance in open‐forest and woodland vegetation in Girraween National Park, south‐east Queensland, Australia, were examined. Cover‐abundance data were collected for shrub and vine species in at least 10 400‐m² plots in each of four study areas. Study areas were within one community type and had burnt most recently either 4 or 9 years previously. Variations in fire frequency allowed us to compare areas that had burnt at least three times in the previous 25 years with less frequently burnt areas, and also woodlands that had experienced a 28‐year interfire interval with more frequently burnt areas. Although species richness did not differ significantly with either time‐since‐fire or fire frequency, both these factors affected community composition, fire frequency being the more powerful. Moisture availability also influenced floristics. Of the 67 species found in five or more plots, six were significantly associated with time‐since‐fire, whereas 11 showed a significant difference between more and less frequently burnt plots in each of the two fire‐frequency variables. Most species, however, did not vary in cover‐abundance with the fire regime parameters examined. Even those species that showed a marked drop in cover‐abundance when exposed to a particular fire regime generally maintained some presence in the community. Five species with the capacity to resprout after fire were considered potentially at risk of local extinction under regimes of frequent fire, whereas two species were relatively uncommon in long‐unburnt areas. Variable fire regimes, which include interfire intervals of at least 15 years, could be necessary for the continuity of all species in the community.     

2D and 3D sulfate-water supramolecular networks templated via triazole-nickel(II) complexes

Tuning the substituents of triazoles, we obtained di- and tri-nuclearic triazole-nickel complexes [Ni₂(deatrz)₄(H₂O)₅](SO₄)₂ · 7H₂O (1) and [Ni₃(dmtrz)₆(H₂O)₆](SO₄)₃ · 21H₂O (2) (deatrz = 3,5-diethanyl-4-amino-1,2,4-triazole; dmtrz = 3,5-dimethanyl-1,2,4-triazole). The X-ray single-crystal diffraction results reveal that sulfate anions and water clusters form supramolecular networks in both complexes. In 1, a supramolecular two-dimensional structure was fabricated by nano-sized grid with novel tetramer water rings templated via binuclear-nickel(II) cations, while in 2, water molecules and sulfate anions construct the first sulfate-water three-dimensional supramolecular network as host to encapsulate trinuclear-nickel guests.