Patterns of allozyme variation in western Eurasian Fagus

Fagus sylvatica L. is one of the most widespread broad‐leaved trees in the temperate forests of the northern hemisphere. In addition to two subspecies, F. sylvatica ssp. sylvatica in Europe and F. sylvatica ssp. orientalis in south‐western Asia, two further taxa were described: F. moesiaca (Maly) Czeczott in the south‐western Balkans and F. taurica Popl. in Crimea. The opinions about the number and ranks of taxa within this complex are highly controversial. To assess the degree of genetic differentiation among them, and to reveal geographical patterns of genetic diversity and their relationships to history and biogeography of beech populations, genetic variation at 12 allozyme loci was studied in 279 populations in western Eurasia. A Bayesian analysis of population structure revealed the existence of two clusters, which fairly well coincided with F. sylvatica ssp. sylvatica and F. sylvatica ssp. orientalis, whereby the populations from the south‐western Balkans and Crimea contained a mixture of these two gene pools. On the other hand, a neighbour‐joining tree based on pairwise F_ST failed to separate the subspecies into well‐defined distinct clades. Populations of F. sylvatica ssp. orientalis proved to be incomparably more differentiated than ssp. sylvatica (F_ST = 0.157 and 0.032, respectively). Asian populations also showed higher levels of allelic richness both on population and taxon levels than the European ones (the number of alleles after rarefaction was 3.40 and 4.27 in F. sylvatica ssp. sylvatica and ssp. orientalis, respectively). This indicates that the gene pool of F. sylvatica ssp. orientalis has not been depleted by reduced population sizes during the Pleistocene glaciations, as is the case of F. sylvatica ssp. sylvatica. Genetic similarities between isolated regional populations are explained by shared ancestral polymorphisms and/or range overlaps with subsequent hybridization in the past. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 154 , 165–174.     

基于定量CT分析哈尔滨地区人群腹部脂肪面积与血脂、血糖的相关性

目的:通过定量CT检测哈尔滨地区人群腹部脂肪面积,并分析其与血脂、血糖水平的相关性.方法:选取于哈医大附属一院体检中心行肺部CT检查、20周岁以上的患者411例,年龄23-90岁,中位年龄58岁.分别进行体格检查和生化指标测定,根据体重指数(Body Mass Index,BMI)值将患者分为正常组、超重组及肥胖组,并...     

天然水环境中纳米银的来源、分析与转化

纳米银(AgNPs)作为当前应用最广的金属纳米材料之一,可通过各种途径进入水土环境,对水生生物产生毒性,从而破坏水体生态环境.天然水体成分复杂,纳米银具有纳米材料特殊的理化性质,使得其在水体中的转化过程变得尤为复杂,因此理解纳米银在水环境中的转化与归趋,对于水质管理与生态环境保护极其重要.现代科技的发展为更好地研究纳米银在进入环境中后的溶解、聚凝等一系列转化过程提供了可能.本文概述了环境中纳米银的来源和环境风险,分析了pH、溶解氧、离子强度等环境因素及粒径、涂层等自身因素对其在水体环境中转化的影响,并归纳了对纳米银的粒径、电位及形貌等分析的主要技术手段.最后指出了当前研究中存在的主要不足,并对今后的研究方向进行了展望.     

The Structure of the Salmonella typhimurium Type III Secretion System Needle Shows Divergence from the Flagellar System

The type III secretion system (T3SS) is essential for the infectivity of many pathogenic Gram-negative bacteria. The T3SS contains proteins that form a channel in the inner and outer bacterial membranes, as well as an extracellular needle that is used for transporting and injecting effector proteins into a host cell. The homology between the T3SS and the bacterial flagellar system has been firmly established, based upon both sequence similarities between respective proteins in the two systems and the structural homology of higher-order assemblies. It has previously been shown that the Shigella flexneri needle has a helical symmetry of ∼ 5.6 subunits/turn, which is quite similar to that of the most intensively studied flagellar filament (from Salmonella typhimurium), which has ∼ 5.5 subunits/turn. We now show that the Sa. typhimurium needle, expected by homology arguments to be more similar to the Sa. typhimurium flagellar filament than is the needle from Shigella, actually has ∼ 6.3 subunits/turn. It is not currently understood how host cell contact, made at the tip of the needle, is communicated to the secretory system at the base. In contrast to the Sa. typhimurium flagellar filament, which shows a nearly crystalline order, the Sa. typhimurium needle has a highly variable symmetry, which could be used to transmit information about host cell contact.     

Early history of helminthology in the Russian Academy of Sciences

Zoological Institute RAS (up to 1930--Zoological Museum) dates back to 1728, when the first Russian museum, Kunstkammer, was opened under the authority of the newly organized Russian Academy of Sciences. Zoological collections of Kunstkammer were greatly enriched by a number of naturalists who worked in Russia since the middle of the 18-th century, P. S. Pallas (1741-1811) and I. T. Koelreuther (1733-1806) were among them. Both had made an essential progress into helminthology. In 1895, Zoological Museum legislatively acquired a statute of the central institution in Russia for zoological research. Investigations of parasitic worms here become permanent. First parasitologists in its staff, A. K. Mordvilko (1867-1938) and N. P. Annenkova-Khlopina (1887-1950), should be mentioned.     

The location of ubiquitin in Lethocerus arthrin

Arthrin is a ubiquitinated actin that is present in flight muscles of some insects. In addition, it has been found in the malaria parasite Plasmodium falciparum. The role of this monoubiquitylation is not clear, and it does not appear to be associated with proteolytic degradation. The stoichiometry of arthrin to actin in Lethocerus indirect flight muscle, 1:6, suggests that there would be one arthrin molecule for each Tm-Tn (tropomyosin-troponin) complex. The appearance of arthrin after tropomyosin and troponin in Drosophila development is consistent with the Tm-Tn complex determining which actin subunit is targeted for conjugation with ubiquitin. We have used a new approach of three-dimensional reconstruction of helical filaments, the iterative helical real space reconstruction method, to extract segments of homogeneous arthrin out of long filaments where the conformation of the ubiquitin is more heterogeneous. Surprisingly, the location of the ubiquitin is on the face of actin subdomain 1, opposite to where tropomyosin binds in the “off” state, suggesting that there could not be a direct interaction between the ubiquitin and the tropomyosin. It is possible that the troponin complex in the “on” state that is bound to one actin strand makes an unfavorable contact with a ubiquitin molecule attached to the opposite actin strand. This might be the basis for a destabilization of the on state at rest length. Lys118 is the most likely residue to which the ubiquitin is conjugated, based upon fitting atomic structures of actin and ubiquitin into the reconstruction.     

Toll样受体对肠道病毒71型基因组RNA的识别分析

目的分析Toll样受体(TLRs)对肠道病毒71型(EV71)基因组RNA的识别。方法用荧光定量RT-PCR方法检测与EV71基因组RNA作用24、48和72 h后人结肠癌SW620细胞的TLR3、TLR7和白细胞介素-6(IL-6)、IL-8、IL-12 m RNA表达。结果细胞的TLR3、TLR7 m RNA和IL-6、IL-12 m RNA在作用72 h后表达增加,IL-8 m RNA各时间点表达无变化。结论 TLR3、TLR7可与EV71基因组RNA识别,并诱导细胞因子IL-6、IL-12活化表达。     

A set of multiplex panels of microsatellite markers for rapid molecular characterization of rice accessions

Background  

This study aimed to analyze the efficiency of three new microsatellite multiplex panels, which were designed to evaluate a total of 16 loci of the rice genome, based on single PCR reactions of each panel. A sample of 548 accessions of traditional upland rice landraces collected in Brazil in the last 25 years was genotyped, a database of allelic frequencies was established, estimates of genetic parameters were performed and analysis of genetic structure of the collection was developed.