924 resultados para 863
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世居云南的少数民族中,壮、傣、水、布依、布朗、德昂、佤、彝、白、怒、哈尼、傈僳、拉祜、纳西、景颇、阿昌、基 诺和独龙18 个民族是由“羌”、“濮”、“越”3 大部落群体演化而来,是云南的土著居民。利用PCR2RFL P 方法对这18 个土著民族进行Y染色体上13 个双等位基因位点进行基因分型。结果显示,不同历史族源的民族群体在Y染 色体双等位基因单倍型分布上具有一定的差异:在百越后裔民族群体中以单倍型H11 、H12 为主要分布;在氐羌后 裔民族中以单倍型H5 、H6 和H8 为主要分布;在百濮后裔民族群体中主要单倍型分布为H6 、H8 和H11 。进一步 主成分分析表明,百越后裔民族群体和氐羌后裔民族在主成分图上聚为两组,提示父系基因库有不同的来源,与历 史记载相印证。
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蛇毒丝氨酸蛋白酶属于糜蛋白酶样丝氨酸蛋白酶。蛇毒丝氨酸蛋白酶几乎可作用于哺乳 动物凝血, 纤溶系统的各个步骤而对凝血、纤溶、血小板功能、血管完整性以及出血等发生影响。蛇 毒丝氨酸蛋白酶具有高度的序列相似性一, 但底物专一性却具较大的分化另一方面, 它们对生理性丝氨酸蛋白酶抑制剂有较强的耐受性及较长的体内半衰期, 这些特性使之成为蛋白 酶结构与功能研究的优良模型, 同时也具广阔的药物开发前景和作为药理研究的工具。
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就离子通道和动物离子通道毒素的来源、种类、特性及其对新药开发的意义进行了综述。各种来源的动物毒素通常分子量较小,富含二硫键,是直接作用于分子靶标(如离子通道、受体及酶)的小分子蛋白质。很多动物毒素对电压门控离子通道具有高度的专一性和有效性,具有独特、简洁的三维空间结构。其对新药的发现、设计以及寻找潜在的治疗靶标具有重要的指导意义。
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While conducting experiments to investigate antimicrobial peptides of amphibians living in the Yunnan-Sichuan region of southwest China, a new family of antimicrobial peptides was identified from skin secretions of the rufous-spotted torrent frog, Amolops loloensis. Members of the new peptide family named amolopins are composed of 18 amino acids with a unique sequence, for example, NILSSIVNGINRALSFFG. By BLAST search, amolopins did no show similarity to any known peptides. Among the tested microorganisms, native and synthetic peptides only showed antimicrobial activities against Staphylococcus aureus ATCC2592 and Bacillus pumilus, no effects on other microorganisms. The CD spectroscopy showed that it adopted a structure of random combined with beta-sheet in water, Tris-HCl or Tris-HCl-SDS. Several cDNAs encoding amolopins were cloned from the skin cDNA library of A. loloensis. The precursors of amolopin are composed of 62 amino acid residues including predicted signal peptides, acidic propieces, and mature antimicrobial peptides. The preproregion of amolopin precursor comprises a hydrophobic signal peptide of 22 residues followed by an 18 residue acidic propiece which terminates by a typical prohormone processing signal Lys-Arg. The preproregions of precursors are very similar to other amphibian antimicrobial peptide precursors but the mature amolopins are different from other antimicrobial peptide families. The remarkable similarity of preproregions of precursors that give rise to very different antimicrobial peptides in distantly related frog species suggests that the corresponding genes form a multigene family originating from a common ancestor. (C) 2008 Elsevier Masson SAS. All rights reserved.
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Much attention has been paid on amphibian peptides for their wide-ranging pharmacological properties, clinical potential, and gene-encoded origin. More than 300 antimicrobial peptides (AMPs) from amphibians have been studied. Peptidomics and genomics analysis combined with functional test including microorganism killing, histamine-releasing, and mast cell degranulation was used to investigate antimicrobial peptide diversity. Thirty-four novel AMPs from skin secretions of Rana nigrovittata were identified in current work, and they belong to 9 families, including 6 novel families. Other three families are classified into rugosin, gaegurin, and temporin family of amphibian AMP, respectively. These AMPs share highly conserved preproregions including signal peptides and spacer acidic peptides, while greatly diversified on mature peptides structures. In this work, peptidomics combined with genomics analysis was confirmed to be an effective way to identify amphibian AMPs, especially novel families. Some AMPs reported here will provide leading molecules for designing novel antimicrobial agents. (C) 2009 Elsevier Inc. All rights reserved
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在大鼠基因组数据库中搜索得到两个泌乳刺激素基因家族的新成员.进一步分析显示该基因家族起源于啮齿目和其他哺乳动物分歧之后,而且大部分基因座位的重排在大、小鼠分歧之前已经完成.但PL-Ⅰ和PL-Ⅱ基因簇却是例外,它们在基因树上以物种特异的方式聚类.结合基因转换的检验、染色体上相对位置比较和基因重复时间估计的结果,认为啮齿目PL-Ⅰ和PL-Ⅱ基因是物种特异的,它们由一系列在大、小鼠分歧之后发生的基因重复事件形成.结果还揭示了在啮齿目泌乳刺激素基因家族进化过程中持续不断的发生了基因重复和基因分化事件.
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对自然感染的水牛源的人肉孢子虫以及黄牛源人肉孢子虫DNA的18S rRNA基因的PCR扩增产物进行了测序。对所获的863 bp的18S rRNA基因分析比较表明,二者有较高的同源性,因此认为二者可能同是一种肉孢子虫——人肉孢子虫(Sarcocystis hominis Railliet and Lucet,1891)。由此推断,不仅黄牛可作为人肉孢子虫的中间宿主,水牛也可作为人肉孢子虫的中间宿主。
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Background: The Galliformes is a well-known and widely distributed Order in Aves. The phylogenetic relationships of galliform birds, especially the turkeys, grouse, chickens, quails, and pheasants, have been studied intensively, likely because of their close association with humans. Despite extensive studies, convergent morphological evolution and rapid radiation have resulted in conflicting hypotheses of phylogenetic relationships. Many internal nodes have remained ambiguous. Results: We analyzed the complete mitochondrial (mt) genomes from 34 galliform species, including 14 new mt genomes and 20 published mt genomes, and obtained a single, robust tree. Most of the internal branches were relatively short and the terminal branches long suggesting an ancient, rapid radiation. The Megapodiidae formed the sister group to all other galliforms, followed in sequence by the Cracidae, Odontophoridae and Numididae. The remaining clade included the Phasianidae, Tetraonidae and Meleagrididae. The genus Arborophila was the sister group of the remaining taxa followed by Polyplectron. This was followed by two major clades: ((((Gallus, Bambusicola) Francolinus) (Coturnix, Alectoris)) Pavo) and (((((((Chrysolophus, Phasianus) Lophura) Syrmaticus) Perdix) Pucrasia) (Meleagris, Bonasa)) ((Lophophorus, Tetraophasis) Tragopan))). Conclusions: The traditional hypothesis of monophyletic lineages of pheasants, partridges, peafowls and tragopans was not supported in this study. Mitogenomic analyses recovered robust phylogenetic relationships and suggested that the Galliformes formed a model group for the study of morphological and behavioral evolution.
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目的 体外测定两种AZT-氟喹诺酮偶联物SRLZ和SROZ的抗HIV-1活性及抗菌活性.方法 通过合胞体抑制、HIV-1感染细胞保护、HIV-1 p24抗原测定等方法检测急性感染中化合物对HIV-1实验株、临床分离株的抑制作用和对慢性感染细胞中的病毒复制影响;通过体外金黄色葡萄球菌的抑制实验检测化合物的抗菌活性.结果 AZT-氟喹诺酮偶联物SRLZ和SROZ能抑制HIV-1实验株诱导的合胞体形成,减少病毒感染细胞的死亡和抑制病毒在细胞内的复制;SRLZ和SROZ对HIV-1临床分离株也有较好的抑制作用;SRLZ和SROZ对HIV-1的抑制活性与AZT相近;AZT-氟喹诺酮偶联物也能抑制金黄色葡萄球菌,其MIC值与其相应的阳性药物相近.结论 SRLZ和SROZ有很好的抗HIV-1活性和抗菌活性.
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树突状细胞(DC)不仅是已知惟一能够激活初始T淋巴细胞的抗原提呈细胞,而且也是已知最强的抗原提呈细胞(APC),其对抗原的提呈能力远大于巨噬细胞.经抗原刺激的DC回输到体内后,能够迁移到淋巴结,释放多种细胞因子,同时激活T淋巴细胞的分化和分裂,产生抗原特异性的细胞毒性T淋巴细胞(CTL),这些细胞因子和特异性CTL能够有效地促进或直接杀伤表达该抗原的细胞.
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蛋白激酶C ( PKC)是一类磷脂依赖的丝氨酸/苏氨酸 蛋白激酶, PKC在中枢神经系统疾病及心血管紊乱等多种人 类疾病中都发挥了重要作用。研究发现, PKC可以通过多种 途径刺激H IV病毒的活化,并磷酸化病毒复制周期中的多 种蛋白,如P17gag、Nef、Rev和Vif等,这些蛋白的磷酸化在 病毒复制周期中起到了不可忽视的作用。了解PKC与H IV 及细胞间的复杂关系,开发抑制PKC蛋白激酶的药物从而 达到抑制H IV复制的目的,或激活PKC从而减少或消除体 内潜伏的H IV病毒库是对PKC在抗H IV研究中应用提出的 两个主要方向,对于开发新型抗H IV药物有重要意义。
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目的:从小花五味子中发现具有抗HIV 活性的化学成分。方法:采用多种柱层析分离进行化合物的分离 和纯化,通过波谱分析鉴定化合物的结构,化合物的抗HIV21 活性通过对HIV21 感染C8166 细胞致细胞病变的抑制试验得 到。结果:从小花五味子的茎藤部分分离得到了4 个木脂素,分别鉴定为micrantherin A (1) , gomisin K3 (2) , gomisin G (3) 和 vladinol F (4) 。化合物4 具有显著的抗HIV21 活性,IC50 = 3151μg/ mL ,选择指数为27145。结论:化合物1 为新的木脂素, 化合物4 的抗HIV21 活性值得进一步研究。
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多糖类化合物种类繁多,许多多糖化合物在体内或体外表现出良好的抗HIV 活性,多糖能 够作用于HIV 复制周期的多个环节,影响tat 、gp120、RT 等多个病毒蛋白的功能。目前,已有多糖 被用于杀微生物剂、抗病毒辅助治疗、抗机会性感染等临床研究中,多糖在临床上存在抗凝血活 性、生物利用度低等问题,但丰富的多糖类化合物因其作用多效性仍有广阔的抗HIV 应用前景。
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HIV 感染人体后造成大量CD4 + T 淋巴细胞的凋亡, 从而破坏免疫系统,使机体无法抵抗病毒的入侵,导致免疫 缺陷。目前的药物靶点都针对病毒本身,无法清除体内储存 病毒的感染细胞,而HIV 蛋白酶抑制剂治疗HIV/ AIDS 患 者后可以减少HIV 感染引起的细胞凋亡,帮助机体恢复免 疫功能,并且这种作用与其抑制病毒的作用是相独立的,这 提示了可以通过免疫重建的策略来治疗AIDS。本文综述了 HIV 蛋白酶抑制剂的研究和发展概况,其作用特点以及对细 胞凋亡的影响。明确HIV 蛋白酶抑制剂与细胞凋亡的关 系,可以启发新的思路从细胞着手,通过恢复机体的免疫能 力来对抗病毒,从根本上治疗AIDS。
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长期以来缺乏病毒体内感染的小动物模型是制约HIV21 研究取得突破性进展的一大障碍。研究者将 胎儿的胸腺和胎肝组织移植到重症联合免疫缺陷(SCID) 小鼠体内, 构建了SCID2hu (Thy/Liv) 人鼠嵌合模型。 该模型具备正常功能性的人造血器官“Thy/Liv”, 较真实地模拟了HIV21 感染人胸腺后的状况, 是研究HIV21 体内感染较成功且很有潜力的嵌合鼠模型。SCID2hu (Thy/Liv) 模型的构建使得在小型动物体内研究HIV 的某 些致病机制、临床前评价各种先导药物的体内抗HIV 活性、评价新的治疗方案及寻求合适的基因治疗等成为可 能, 为在体内研究人造血系统和免疫系统的病理生理机能及人干细胞基因治疗提供了有力的工具, 有广泛的应 用前景。