文摘（000111-000140）

000111 生物信息学技术克隆人类神经髓鞘蛋白零家族基因[中]/唐冬生…//生物化学与生物物理学报.-2000,32(4).-364-368 为克隆新的髓鞘蛋白相关基因,将MPZ基因编码区Cdna序列与EST数据库进行同源性比较,得到与MPZ显著相似的2个EST,构建成801 bp的重叠群.此重叠群与定位在1q24的128kb Gdna的相似性为100%.计算机分析表明801 bp的重叠群可能存在一个435 bp的阅读框架.在重叠群上设计两个引物与文库载体臂上的引物配对,扩增各种Cdna文库DNAW和巢式PCR.     

CLUSTERING POPULATIONS BY MIXED LINEAR MODELS

INTRODUCTIONInevolutionstudiesandplant(oranimal)breedingresearch,clusteranalysesarewidelyusedforgroupingpopulations.Therehavebeenalotofmethodsdevelopedforgroupingpopulations(SneathandSokal,1973;Eve-ritt,1993).Variousmethodsaredifferedinthewaysfordistance(…     

虹鳟鱼(Salmo grairdneri Richard)基因文库的构建及生长激素基因的克隆和亚克隆

以噬菌体EMBL3作为载体,构建了虹鳟鱼的全基因文库,制备了包装蛋白效率达4.6×10~8Pfu/μgDNA.基因文库重组噬菌的量为8.2×10~5pfu/μgDNA.同时用含虹鳟鱼生长激素基因cDNA的pAF-51△S作为探针,从该文库中筛选出两个阳性噬斑,复筛获得90％以上的阳性斑。并从阳性克隆中回收虹鳟收生长激素基因片段为6kb,亚克隆到puc-18质粒中,进行了酶切分析。     

Expression of a soluble form of CTLA4 on macrophage and its biological activity

INTRODUCTI0NItisrecentlyreportedthatB7andCD28/CTLA4pathwayplaysacriticalroleintheactivationofT-ce1l[1-3],aswellasintheonsetofautoimmunitybothinhumanandmurinem0delofaut0immunity[4-7].B7moleculesareexpressedonavarietyofcelltypes,includingdentriticcells,Bcells,T-cellsandmacrophages[8-1l].CTLA4Ig,asolubleform0fCTLA4,cou1db10ckB7andCD28/CTLA4pathwayandresultsintheinhibitationofT-cellactivationandautoimmuneresponse[12-19].ThemacrophagicMm1ce1llinewasregardedasag0odmodelforstudyingmacr…     

ΓОРИЗОНТ С Polydesmia И ИХ РОДСТВЕННЫЕ СВЯЗИ С Ordosoceras

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Ixodid tick salivary gland products target host wound healing growth factors

For successful blood-feeding, ticks must confront the host immune system comprising many cells and signaling molecules, mainly cytokines and growth factors. These factors bind to specific receptors on the cell membranes, thereby initiating a signaling cascade that leads to distinct cellular activities. Ticks are able to manipulate host immune responses via molecules secreted from their salivary glands. Saliva of ixodid ticks contains factors binding important cytokines and their subgroup, chemokines. Here we demonstrate that constituents of tick salivary gland extract (SGE) also appear to bind growth factors: transforming growth factor beta (TGF-β1), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF-2), and hepatocyte growth factor (HGF), depending on tick species. SGE derived from Amblyommavariegatum reacted with TGF-β1, PDGF, FGF-2 and HGF; Dermacentorreticulatus and Rhipicephalusappendiculatus with TGF-β1, FGF-2 and HGF; and Ixodes ricinus and Ixodesscapularis with PDGF. SGE from the species targeting PDGF (A. variegatum and I. ricinus) also inhibited cell proliferation in vitro and induced a change in morphology of different cell lines. These effects correlated with disruption of the actin cytoskeleton. Such effects were not observed with SGE of the two species that did not target PDGF. Targeting of wound healing growth factors appears to be yet another strategy ixodid ticks adopt for suppression of inflammation and successful haematophagy.     

Correlation between mammalian cell cytotoxicity of flavonoids and the redox potential of phenoxyl radical/phenol couple

Flavonoids exhibit prooxidant cytotoxicity in mammalian cells due to the formation of free radicals and oxidation products possessing quinone or quinomethide structure. However, it is unclear how the cytotoxicity of flavonoids depends on the ease of their single-electron oxidation in aqueous medium, i.e., the redox potential of the phenoxyl radical/phenol couple. We verified the previously calculated redox potentials for several flavonoids according to their rates of reduction of cytochrome c and ferricyanide, and proposed experimentally-based values of redox potentials for myricetin, fisetin, morin, kaempferol, galangin, and naringenin. We found that the cytotoxicity of flavonoids (n=10) in bovine leukemia virus-transformed lamb kidney fibroblasts (line FLK) and murine hepatoma (line MH-22a) increases with a decrease in their redox potential of the phenoxyl radical/phenol couple and an increase in their lipophilicity. Their cytotoxicity was decreased by antioxidants and inhibitors of cytochromes P-450, α-naphthoflavone and isoniazide, and increased by an inhibitor of catechol-O-methyltransferase, 3,5-dinitrocatechol. It shows that although the prooxidant action of flavonoids may be the main factor in their cytotoxicity, the hydroxylation and oxidative demethylation by cytochromes P-450 and O-methylation by catechol-O-methyltransferase can significantly modulate the cytotoxicity of the parent compounds.     

转染瘤提供新的镶嵌抗体

在大约100年以前,人们就已证明,在血清中循环的抗体提供了免疫反应的基础。随着血清电泳的发展,人们又证明了这些抗体是蛋白质分子。多年来的研究已经揭示出:抗体负责对细菌和病毒疾病的特异保护作用,同时也包括正常的或与疾病有关的各种免疫反应,如炎症自身免疫性疾病,排移反应,以个体基因为介导的网状调节作用。     

高温对番茄幼苗生长和花芽分化的影响

为了探讨高温胁迫对番茄幼苗生长和花芽分化的影响,该试验以‘中杂9号’番茄为材料,以25℃/15℃(昼/夜)为对照(CK),进行37℃/27℃(昼/夜)的高温处理,测定番茄幼苗生长和花芽分化相关指标。结果表明:从高温处理第3天开始番茄幼苗株高和节间长显著高于对照,而茎粗显著小于对照,即植株出现徒长;高温处理的番茄叶面积、根系表面积一直显著低于常温对照,而根系体积、根系总长和分根数也从第3天开始显著低于对照水平;高温处理的植株花芽分化进程从第1天起就明显加快,高温处理第9天时花芽分化数显著减少,而花芽大小高温处理后1～5 d大于对照,从第7天起高温处理植株的花芽大小显著低于对照。研究表明,高温抑制番茄幼苗营养生长,加快番茄花芽分化进程,减少花芽分化数,并减小花芽大小,最终导致产量降低。