In vivo study on the effects of microcystin extracts on the expression profiles of proto-oncogenes (c-fos, c-jun and c-myc) in liver, kidney and testis of male Wistar rats injected i.v. with toxins

Microcystins (MCs) are a potent liver tumor promoter, possessing potent tumor-promoting activity and weak initiating activity. Proto-oncogenes are known to be involved in the tumor-promoting mechanisms of microcystin-LR. However, few data are available on the effects of MCs oil proto-oncogenes in the whole animal. To investigate the effects of MCs on the expression profile of the proto-oncogenes in different organs, male Wistar rats were injected intravenously with microcystin extracts at a dose of 86.7 mu g MC-LR eq/kg bw (MC-LR eq, MC-LR equivalents). mRNA levels of three proto-oncogenes c-fos, c-jun and c-myc in liver, kidney and testis were analyzed using quantitative real-time PCR at several time points post-injection. Significant induction of these genes at transcriptional level was observed in the three organs. In addition, the increase of mRNA expression of all three genes was much higher in liver than in kidney and testis. Meanwhile, the protein levels of c-Fos and c-Jun were investigated by western blotting. Both proteins were induced in the three organs. However, elevations of protein levels were Much lower than those of mRNA levels. These findings suggest that the expression of c-fos, c-jun and c-myc might be one possible mechanism for the tumor-promoting activity and initiating activity of microcystins. (c) 2008 Published by Elsevier Ltd.

鲤科鱼类的c-myc CDS及其系统发育关系

鲤科鱼类在东亚的物种多样,分布广泛,物种特征尺寸差异明显,弄清其功能基因的系统演变,对于理解物种分化和功能进化具有重要意义.以具有重要生长调控作用的c-myc基因为标记,通过PCR扩增、克隆和测序,共获得41种鲤科鱼类和外类群c-myc基因全序列,发现并分析了c-myc编码区的两个高变异区.基于c-myc CDS序列,分别采用最大简约法(MP)、最大似然法(ML)和Bayesian法重建了鲤科鱼类的系统发育关系.3种方法所得系统发育关系较为相似.当以亚口鱼科的胭脂鱼(Myxocyprinus asiati

The c-myc coding DNA sequences of cyprinids (Teleostei : Cypriniformes): Implications for phylogeny

The family Cyprinidae is one of the largest fish families in the world, which is widely distributed in East Asian, with obvious difference in characteristic size among species. The phylogenetic analysis of cyprinid taxa based on the functionally important genes can help to understand the speciation and functional divergench of the Cyprinidae. The c-myc gene is an important gene regulating individual growth. In the present study, the sequence variations of the cyprinid c-myc gene and their phylogenetic significance were analyzed. The 41 complete sequences of the c-myc gene were obtained from cyprinids and outgroups through PCR amplification and clone. The coding DNA sequences of the c-myc gene were used to infer molecular phylogenetic relationships within the Cyprinidae. Myxocyprinus asiaticus (Catostomidae), Misgurnus anguillicaudatus (Cobitidae) and Hemimyzon sinensis (Homalopteridae) were assigned to the outgroup taxa. Phylogenetic analyses using maximum parsimony (MP), maximum likelihood (ML), and Bayesian retrieved similar topology. Within the Cyprinidae, Leuciscini and Barbini formed the monophyletic lineage respectively with high nodal supports. Leuciscini comprises Xeno-cyprinae, Cultrinae, East Asian species of Leuciscinae and Danioninae, Gobioninae and Acheilognathinae, and Barbini contains Schizothoracinae, Barbinae, Cyprininae and Labeoninae. Danio rerio, D. myersi and Rasbora trilineata were supposed to separate from Leuciscinae and Barbini and to form another lineage, The positions of some Danioninae species were still unresolved. Analyses of both amino acid variation with parsimony information and two high variation regions indicated that there is no correlation between variations of single amino acid or high variation regions and characteristic size of cyprinids. In,addition, the species with smaller size were usually found to be basal within clades in the tree, which might be the results of the adaptation to the primitive ecology and survival pressure.

人、黑猩猩和叶猴FKN全基因的克隆及体外表达的比较研究

下载PDF阅读器目的:克隆人、黑猩猩和叶猴FKN全基因及体外表达,比较研究FKN在进化过程中基因组水平和蛋白表达水平的差异.方法:应用基因重叠延伸拼接PCR法(Gene splicing by overlapping extension PCR,SOE-PCR)将FKN的3个外显子编码序列依次进行前后拼接,然后插入pcDNA3.1/myc-His(-)A真核表达载体中,经酶切、测序鉴定后转染CHO细胞体外表达,RT-PCR、SDS-PAGE和Western blot检测其表达产物.结果:酶切、测序鉴定证实插入的基因片段为完整的FKN,RT-PCR可从转染的CHO细胞中扩增出一条与目的基因大小一致的DNA片段,其表达蛋白能分泌至胞外,SDS-PAGE显示其分子量约为95 000,抗c-myc抗体可与载体上的c-myc蛋白特异性结合.测序显示人、黑猩猩和叶猴相比,FKN基因除了有散在的点突变外,还发现有一明显的30 bp的缺失,但此缺失对FKN蛋白的表达并不影响.结论:成功克隆人、黑猩猩和叶猴FKN全基因,基因组水平和蛋白表达水平的比较研究为后续探讨FKN在高级灵长类物种进化过程中免疫学功能的演变奠定基础.

核基因在鸟类分子系统发育学研究中的应用

核基因作为一种新的遗传标记,近年来被广泛应用于鸟类分子系统发育研究中.核基因与线粒体基因位于不同的遗传载体上,因此被引入到系统发育学研究中为物种树的重建提供独立的证据.常用的外显子标记为重组激活基因1(RAG-1),重组激活基因2(RAG-2),癌基因c-myc,原癌基因c-mos,它们由于缓慢的进化速率而被用于鸟类高级分类阶元的系统学研究中.常用的内含子标记是β纤维蛋白原基因内含子7(β-fibrinogen intron7,β-fibint7),肌红蛋白基因内含子Ⅱ(myoglobin intionⅡ).内含子标记通常与线粒体序列联合使用,形成具有互补系统发育信号的数据集,应用于各种分类阶元的系统学研究中.

中国鸟类的DNA分类及系统发育研究概述

鸟类分类是鸟类学其他研究领域的基础,近年来分子技术的发展,以及计算机技术的应用为鸟类分类学和鸟类系统演化研究提供了新的研究手段,给传统的系统分类研究带来了新的机遇.Tautz等于2002年首先提出运用DNA序列作为生物分类系统的主要平台,即DNA分类学(DNA Taxonomy).而Hebert等于2003年则首次提出了DNA条形码(DNA Barcoding)的概念,并对其物种分类和鉴定意义予以肯定,建议利用线粒体细胞色素C氧化酶亚单位Ⅰ(COI)的特定区段来做DNA条形编码的基础.在鸟类DNA分类方面,国内学者应用线粒体基因Cut b,COI,c-mos,c-myc,12s rRNA,16s rRNA,ND2,ND3,CR,RAG-1以及核基因myoglobin introⅡ等不同片段对很多类群进行了分类探讨和系统发育研究.但是主要集中在鸡形目及雀形目鸟类.中国是鸟类多样性极其丰富的国家,近年来很多亚种、种及以上分类阶元依然存在问题,因此,中国鸟类物种的分类地位、系统发育与演化关系等依然有很多问题等待深入研究.目前国内基于COI的鸟类分类及系统发育研究有了一些报道,但是真正的DNA条形码工作尚需继续、深入地开展.

人类基因组中保守二级结构的纯净化选择及其在转录调控网络中的作用

保守序列是一种跨物种保守的基因组序列，而且绝大多数为非蛋白编码序 列。保守序列在人类遗传疾病中发挥着重要作用。其中，一部分保守序列能够 折叠形成二级结构。已鉴定的一些保守二级结构编码一些RNA 分子，如 microRNA、RNA 编辑序列和组蛋白mRNA 3’端非翻译区茎环结构等。但是，对 于绝大部分的保守二级结构，它们的生物学功能以及作用于它们上面的进化作 用力依然是未知的。 群体的SNP 数据在分析序列上的进化作用力时非常有效。SNP 在群体中的 频率会因为受到不同的进化作用力而表现出差异，而与其是否位于基因组中的 突变热点无关。对于受纯净化选择作用的SNP，它们的频率一般会比中性SNP 具有低的新生型等位基因频率（DAF）。我们运用生物信息学的方法，在人类基 因组保守二级结构中找到746 个SNP。这746 个SNP 与基因组其它区段的SNP 在突变模式上并不存在显著差异，在保守二级结构内同样存在突变热点。通过 与侧翼序列SNP 的分布比较发现，保守二级结构上SNP 密度约为其侧翼序列的 2/3。相比于侧翼序列SNP，有更高比例的保守二级结构SNP 具有低的DAF 值。 这些结果提示，有很多保守二级结构上的SNP 因为受到纯净化选择作用而在现 代人群中被剔除了。保守二级结构与侧翼序列在SNP 密度和DAF 上的差异要高 于保守序列与非保守序列之间的差异，提示保守二级结构是受到纯净化选择作 用最为严格的一类保守序列。我们发现，在保守二级结构内部，纯净化选择作 用的强度也有差异。茎区比环区具有更低的SNP 密度，而且有更高比例的茎区 SNP 具有低的DAF 值。这个结果提示，保守二级结构上的纯净化选择力主要作 用于茎区上的位点。我们推测，这可能是茎区上的突变往往比环区的突变对二级结构的造成更大的影响导致的。 我们通过寻找保守二级结构与转录因子SOX2、OCT4、NANOG、SUZ12 和C-MYC 结合位点之间的重叠，还分析了保守二级结构在转录调控网络中的作用。结果 显示，很多保守二级结构是作为转录因子的结合位点调控了许多与发育相关的 转录因子编码基因的表达。转录因子与保守二级结构之间的结合模式非常复杂， 可以有多个转录因子结合到同一个保守二级结构上，也可以是一个转录因子结 合到自身编码基因相关的保守二级结构上。不同的转录因子和保守二级结构结 合可以主导靶基因的特异模式，当绝大多数相关的保守二级结构与SUZ12 结合 时，基因表达受到抑制，而当绝大多数相关的保守二级结构不与SUZ12 结合时， 基因表达受到激活。在转录调控网络中，约有30%的保守二级结构是作为启动 子来调控基因的表达。因为转录因子SOX2、OCT4、NANOG、SUZ12 和C-MYC 仅仅 只结合到很小一部分保守二级结构上，提示可能还有更多的转录因子会结合到 保守二级结构上。因此，保守二级结构介导的转录调控网络要比目前已知的复 杂得多。

Rhein induces apoptosis and cell cycle arrest in human hepatocellular carcinoma BEL-7402 cells

Rhein, an anthraquinone derivative of rhubarb, inhibits the proliferation of various human cancer cells. In this paper, we focused on studying the effects of rhein on human hepatocelluar carcinoma BEL-7402 cells and further understanding the underlying molecular mechanism in an effort to make the potential development of rhein in the treatment of cancers. Using MTT assay and flow cytometry, we demonstrate a critical role of rhein in the suppression of BEL-7402 cell proliferation in a concentration- and time-dependent manner. The increase of apoptosis rate was observed after incubation of BEL-7402 cells with rhein at 50-200 mu M for 48 hours, and the cells exhibit typical apoptotic features including cellular morphological change and chromatin condensation. Moreover, rhein-induced cell cycle S-phase arrest. Additionally, after rhein treatment, expression levels of c-Myc gene were decreased, while those of caspase-3 gene were increased in a dose-dependent manner by using real-time PCR assay. The results demonstrate for the first time that cell cycle S-phase arrest is one of the mechanisms of rhein in inhibition of BEL-7402 cells. Rhein plays its role by inducing cell cycle arrest via downregulation of oncogene c-Myc and apoptosis through the caspase-dependent pathway. It is expected that rhein will be effective and useful as a new agent in hepatocelluar carcinoma treatment in the future.

Deconfinement phase Transition including perturbative QCD corrections in (proto)neutron star matter

Deconfinement phase transition and neutrino trapping in (proto)neutron star matter are investigated in a chiral hadronic model (also referred to as the FST model) for the hadronic phase (HP) and in the color-flavor-locked (CFL) quark model for the deconfined quark phase. We include a perturbative QCD correction parameter alpha(s) in the CFL quark matter equation of states. It is shown that the CFL quark core with K-0 condensation forms in neutron star matter with the large value of alpha(s). If the small value of alpha(s) is taken, hyperons suppress the CFL quark phase and the HP is dominant in the high-density region of (proto)neutron star matter. Neutrino trapping makes the fraction of the CFL quark matter decrease compared with those without neutrino trapping. Moreover, increasing the QCD correction parameter alpha(s) or decreasing the bag constant B and the strange quark mass m(s) can make the fraction of the CFL quark matter increase, simultaneously, the fraction of neutrino in protoneutron star matter increases, too. The maximum masses and the corresponding radii of (proto)neutron stars are not sensitive to the QCD correction parameter alpha(s).

Nonequilibrium microstructures and their evolution in a Fe-Cr-W-Ni-C laser clad coating

The laser-solidified microstructural and compositional characterization and phase evolution during tempering at 963 K were investigated using an analytical transmission electron microscope with energy dispersive X-ray analysis. The cladded alloy, a powder mixture of Fe, Cr, W, Ni, and C with a weight ratio of 10:5:1:1:1, was processed with a 3 kW continuous wave CO2 laser. The processing parameters were 16 mm/s beam scanning speed, 3 mm beam diameter. 2 kW laser power, and 0.3 g/s feed rate. The coating was metallurgically bonded to the substrate, with a maximum thickness of 730 mu m, a microhardness of about 860 Hv and a volumetric dilution ratio of about 6%. Microanalyses revealed that the cladded coating possessed the hypoeutectic microstructure comprising the primary dendritic gamma-austenite and interdendritic eutectic consisted of gamma-austenite and M7C3 carbide. The gamma-austenite was a non-equilibrium phase with extended solid solution of alloying elements and a great deal of defect structures, i.e. a high density of dislocations, twins, and stacking faults existed in gamma phase. During high temperature aging, in situ carbide transformation occurred of M7C3 to M23C6 and M6C. The precipitation of M23C6, MC and M2C carbides from austenite was also observed.

铁基抗高温磨损激光熔覆涂层强韧设计和研究II:Fe-Cr-C-W-Ni激光熔覆层的微观组织及性能

本文以对热工模具进行失效分析的基础上，利用激光熔覆技术，在５ＣｒＭｎＭｏ基础上设计并制备强韧兼备的抗高温磨损涂层。