共查询到20条相似文献，搜索用时 15 毫秒
1.
Rat resistance to schistosomiasis: platelet-mediated cytotoxicity induced by C-reactive protein 总被引：6，自引：0，他引：6
In rats infected with the parasite Schistosoma mansoni, the concentration of C-reactive protein in the serum increases after the lung stage of infection and is at its highest at the time of terminal worm rejection. The peak of platelet-mediated cytotoxicity induced by infected serum that has been heated (and is free of immunoglobulin E) as well as the time course for the development of platelet cytotoxic activity in infected rats was found to be correlated with the concentration of C-reactive protein. Rat and human platelets treated with homologous serum obtained during an acute phase of inflammation or with purified C-reactive protein were able to kill the immature forms of the worm in vitro. Platelets treated with C-reactive protein were furthermore capable of conferring significant protection against schistosomiasis in transfer experiments. Collectively these data indicate that a system that includes C-reactive protein and platelets participates in the natural resistance of the rat to schistosomal infection. 相似文献
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为探讨IGF-1基因对北京鸭胸肌发育的影响,试验克隆了北京鸭IGF-1 cDNA的部分序列,分析了其核苷酸及编码的氨基酸序列与其他物种的同源性,并检测了IGF-1 mRNA在不同日龄北京鸭胸肌中表达的发育性变化。结果表明,克隆的鸭IGF-1 cDNA部分序列长507 bp,编码168个氨基酸,核苷酸序列与鸡、家鸭、鹌鹑、火鸡、鸵鸟、人和猪的同源性分别为98％,99％,97％,98％,96％,84％和82％,编码的氨基酸序列与家鸭、鸡、火鸡、鹌鹑、人、挪威鼠和猪的同源性分别为99％,98％,97％,97％,84％,79％和84％。表明北京鸭与家鸭的亲缘关系最近,与鸡、鹌鹁、火鸡、鸵鸟也有较近的亲缘关系;北京鸭胸肌中IGF-1 mRNA表达丰度在7,14,21 日龄间和28, 35,42日龄间的差异均不显著(P>0．05),但28,35,42 日龄显著高于7,14,21日龄(P<0．05),说明在北京鸭胸肌发育较快的时期,IGF-1 mRNA表达量也较高,IGF-1 mRNA的表达量与胸肌的发育呈正相关。 相似文献
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The primary structure and heterogeneity of tau protein from mouse brain 总被引：74，自引：0，他引：74
Tau protein is a family of microtubule binding proteins, heterogeneous in molecular weight, that are induced during neurite outgrowth and are found prominently in neurofibrillary tangles in Alzheimer's disease. The predicted amino acid sequences of two forms of tau protein from mouse brain were determined from complementary DNA clones. These forms are identical in their amino-terminal sequences but differ in their carboxyl-terminal domains. Both proteins contain repeated sequences that may be tubulin binding sites. The sequence suggests that tau is an elongated molecule with no extensive alpha-helical or beta-sheet domains. These complementary DNAs should enable the study of various functional domains of tau and the study of tau expression in normal and pathological states. 相似文献
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Circumsporozoite protein of Plasmodium vivax: gene cloning and characterization of the immunodominant epitope 总被引：13，自引：0，他引：13
D E Arnot J W Barnwell J P Tam V Nussenzweig R S Nussenzweig V Enea 《Science (New York, N.Y.)》1985,230(4727):815-818
The gene encoding the circumsporozoite (CS) protein of the human malaria parasite Plasmodium vivax has been cloned. The deduced sequence of the protein consists of 373 amino acids with a central region of 19 tandem repeats of the nonapeptide Asp-Arg-Ala-Asp/Ala-Gly-Gln-Pro-Ala-Gly. A synthetic 18-amino acid peptide containing two tandem repeats binds to a monoclonal antibody directed to the CS protein of Plasmodium vivax and inhibits the interaction of this antibody with the native protein in sporozoite extracts. The portions of the CS gene that do not contain repeats are closely related to the corresponding regions of the CS genes of two simian malarias, Plasmodium cynomolgi and Plasmodium knowlesi. In contrast, the homology between the CS genes of Plasmodium vivax and Plasmodium falciparum, another malaria parasite of humans, is very limited. 相似文献
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该研究运用RT-PCR技术,首次从大熊猫Ailuropoda melanoleuca的肌肉组织总RNA中成功克隆了AP2S1基因的编码序列,并对其进行了全面分析.结果表明:大熊猫AP2S1基因编码序列克隆片段全长为512bp,开放阅读框(ORF)为429bp,编码142个氨基酸的蛋白质,该蛋白的相对分子质量为1.7×104,等电点pI为5.82,含有4种类型共5个功能位点,即1个蛋白激酶C磷酸化位点、2个酪蛋白激酶Ⅱ磷酸化位点、1个N-酰基化位点和1个网格蛋白调节素小肽链标签;且该蛋白在哺乳动物网状细胞中的半寿期(half-life)大于30h,不稳定指数(in-stability index)为26.99,属于稳定蛋白.进一步分析发现,大熊猫AP2S1基因与已报道的人、苏门答腊猩猩、牛、褐家鼠和小家鼠5个哺乳动物物种的编码序列及其编码的氨基酸序列具有很高的相似性,表明该基因及其编码蛋白在物种漫长的进化过程中极其保守. 相似文献
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采用RT-PCR方法从河南地区甘蔗花叶病毒(Sugarcane mosaic virus,SCMV)感染的玉米叶片中,克隆了辅助成分-蛋白酶基因(helper component.proteinase,HC-Pro).该基因长1 380 bp,编码460个氨基酸.序列比对表明.HC-Pro编码的氨基酸序列与北京、山东地区SCMV分离物的相似性分别达到97%和98%.而与以前数据库登录的河南分离物的相似性仅98%,说明河南地区SCMV可能发生了变异.选取长582 bp的HC-Pro片段,构建了表达发夹RNA的基因沉默双元表达载体pRNAi-HC-Pro(±),成功转化了农杆菌LBA4404. 相似文献
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采用RT-PCR方法扩增和克隆了鲈鱼白细胞介素-8(LjIL-8)的编码阅读框。该编码阅读框由300个核苷酸组成,编码由99个氨基酸组成前体蛋白。LjIL-8氨基酸序列与哺乳动物和鱼类IL-8类似物的氨基酸同源性分别为23%~48%和25%~92%。氨基酸序列分析表明,N端存在一长23个氨基酸的信号肽,含有形成2个链内二硫键的4个半胱氨酸。分子进化分析表明,LjIL-8与欧洲鲈鱼的亲缘关系最近。将LjIL-8编码序列克隆到原核表达载体pET-28a (+),转化E.coli BL21(DE3)后用IPTG进行诱导表达,SDS-PAGE检测结果表明,预期分子量大小的小分子蛋白在大肠杆菌中成功表达,Western-blotting检测结果显示,目的蛋白能与抗6×His单克隆抗体发生特异性反应。 相似文献
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根据GeneBank发表的猪心脏脂肪酸结合蛋白（heart fatty acid-binding protein,H-FABP）基因序列,设计合成一对引物,从杜长大三元杂交猪的腰大肌中提取总RNA,对H-FABP基因进行RT-PCR扩增,产物经琼脂糖电泳分析,呈现一条约124 bp的条带,回收纯化后,将其克隆至pMD18-T质粒载体中,然后进行核苷酸序列分析。与GeneBank中报道的H-FABP基因比较后发现,该基因片段与其它的核苷酸的同源性为94%～100%,推导的氨基酸的同源性为100%. 相似文献
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A thermodynamic scale for the helix-forming tendencies of the commonly occurring amino acids 总被引：76，自引：0，他引：76
Amino acids have distinct conformational preferences that influence the stabilities of protein secondary and tertiary structures. The relative thermodynamic stabilities of each of the 20 commonly occurring amino acids in the alpha-helical versus random coil states have been determined through the design of a peptide that forms a noncovalent alpha-helical dimer, which is in equilibrium with a randomly coiled monomeric state. The alpha helices in the dimer contain a single solvent-exposed site that is surrounded by small, neutral amino acid side chains. Each of the commonly occurring amino acids was substituted into this guest site, and the resulting equilibrium constants for the monomer-dimer equilibrium were determined to provide a list of free energy difference (delta delta G degree) values. 相似文献
13.
De novo design, expression, and characterization of Felix: a four-helix bundle protein of native-like sequence 总被引：30，自引：0，他引：30
The protein Felix was designed de novo to fold into an antiparallel four-helix bundle of specific topology. Its sequence of 79 amino acid residues is not homologous to any known protein sequence, but is "native-like" in that it is nonrepetitive and contains 19 of the 20 naturally occurring amino acids. Felix has been expressed from a synthetic gene cloned in Escherichia coli, and the protein has been purified to homogeneity. Physical characterization of the purified protein indicates that Felix (i) is monomeric in solution, (ii) is predominantly alpha-helical, (iii) contains a designed intramolecular disulfide bond linking the first and fourth helices, and (iv) buries its single tryptophan in an apolar environment and probably in close proximity with the disulfide bond. These physical properties rule out several alternative structures and indicate that Felix indeed folds into approximately the designed three-dimensional structure. 相似文献
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利用电子克隆的方法设计特异引物,克隆陆地棉的1个二硫键异构酶(Protein disulphide isomerase like)基因的全长序列。序列分析表明:该基因没有内含子,开放阅读框的长度为1 293bp,编码的多肽序列含有430个氨基酸。该基因与红麻HcPDIL5-2a基因具有97%的相似性,将该基因命名为棉花GhPDIL5-2a。取单核期花药进行半定量RT-PCR分析发现:GhPDIL5-2a在陆地棉洞A不育株和可育株花药中表达无差异,在供试的其他不同品种中的表达也无差异。 相似文献
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应用PCR法从弓形虫QHO株速殖子基因组DNA中扩增ROP2的基因片断,连接到pMD18-T载体中,转化大肠杆菌JM109,经酶切及PCR鉴定后进行测序,并进行序列分析.结果表明,自然弱毒株的开放阅读框架(ORF)与ROP2基因已知序列(Z36906)的ORF具有97%的同源性,氨基酸序列具有95%的同源性. 相似文献
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[目的]深入了解捕食线虫性真菌几丁质酶的生物学功能,为今后以少孢节丛孢菌重组几丁质酶AO-379研发线虫病生物防控制剂打下基础.[方法]克隆少孢节丛孢菌XJ-A1几丁质酶AO-379基因的全长序列,利用Signal P4.1 Server、InterPro、ExPASy等在线分析软件对其进行生物信息学分析;构建重组表达载体pET32a-AO-379,转化大肠杆菌BL21(DE3)感受态细胞后用IPTG进行诱导表达,并以SDS-PAGE和Western blotting检测分析表达获得的融合蛋白.[结果]少孢节丛孢菌几丁质酶AO-379基因全长1475bp,含有1个1203bp的开放阅读框(ORF),编码400个氨基酸.几丁质酶AO-379基因序列与少孢节丛孢菌标准株(ATCC 24927)几丁质酶基因序列的同源性为97.08%,其推导氨基酸的同源性为98.75%.几丁质酶A0-379属于糖苷水解酶18家族,具有SXGG和VDGFDLDFE两个催化区保守序列.其中,SLGGS位于第127~131位,为底物结合位点;VDGFDLDFE位于第173~181位,为水解酶催化活性位点.经大肠杆菌诱导表达获得的融合蛋白AO-379相对分子质量为60.0kD,且能与抗少孢节丛孢菌多克隆抗体发生反应.[结论]少孢节丛孢菌几丁质酶AO-379可在大肠杆菌中成功诱导表达,且获得的融合蛋白AO-379能与抗少孢节丛孢菌多克隆抗体发生反应,可用于研发线虫病生物防控制剂. 相似文献
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利用反转录聚合酶链式反应,结合快速扩增cDNA末端(RACE)技术,克隆了甘薯茎线虫乙酰胆碱酯酶基因cDNA Dd-ace-1.该cDNA序列5′端存在反式剪接引导序列SL1,全长2196bp,包含1个1908bp的开放阅读框(GenBank登录号EF583059);在推导出的635个氨基酸残基的前体蛋白中,N端的前24个氨基酸残基为信号肽,随后的611个氨基酸残基是成熟的乙酰胆碱酯酶序列,其预测的相对分子质量为70144.12.在一级结构中,形成催化活性中心的3个氨基酸残基(Ser223、Glu360和His483)、胆碱结合位点Trp(106)以及在亚基内形成二硫键的6个半胱氨酸完全保守;在电鳐(Torpedo californica)乙酰胆碱酯酶分子的催化功能域中存在14个保守的芳香族氨基酸残基,其中10个在甘薯茎线虫乙酰胆碱酯酶中完全保守.该酶的氨基酸序列与南方根节线虫(Meloidogyne incognita)、胎生网尾线虫(Dictyocaulus viviparous)和秀丽小杆线虫(Caenorhabditis elegans)ACE-1的同源性为68.6%、67.2%和66.3%.与其他线虫乙酰胆碱酯酶的聚类分析显示,该乙酰胆碱酯酶(Dd-ACE-1)与其他线虫乙酰胆碱酯酶ACE-1同属一个支系. 相似文献
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日本血吸虫新基因SjPP的筛选、克隆及对小鼠的免疫效果 总被引：8，自引：0，他引：8
【目的】筛选克隆东方田鼠血清识别的日本血吸虫靶抗原基因，并研究其免疫保护效果。【方法】利用东方田鼠感染血清免疫筛选日本血吸虫（中国大陆株）成虫cDNA表达文库获得阳性克隆，以5′ RACE技术扩增获基因全长序列，构建含目的基因的核酸疫苗并研究在小鼠中的免疫保护效果。【结果】（1）获得4个日本血吸虫新的EST序列，即mfs-1（GenBank登录号BE974942）、mfs-3（GenBank登录号BE974944）、mfs-4（GenBank登录号BE974945）和mfs-5（GenBank登录号BE974946）。（2）mfs-5进行全长序列克隆，获得的日本血吸虫新基因SjPP(GenBank登录号AY902477)长1311 bp, 编码302个氨基酸，理论分子量为34.7 kD，等电点为5.51；其氨基酸序列具有丝/苏氨酸蛋白磷酸酶（serine/threonine specific protein phosphatase，简称PP）的保守序列LRGNHE，并且含有该酶特异性抑制剂冈田酸的作用位点SAPNYC，与人的PP6、鼠PP6、果蝇PPⅤ等蛋白的氨基酸序列具有高度同源性，分别达72%、70%和70%。（3）成功构建核酸疫苗pCMV-Script／SjPP，免疫BALB/c小鼠诱导产生肝组织减卵率为23.91%，粪便减卵率为31.91%。【结论】（1）获得日本血吸虫新的抗原基因SjPP。（2）含SjPP基因的核酸疫苗在小鼠中诱导了部分免疫保护效果。 相似文献
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热激蛋白（ HSP）是生物适应环境温度变化的重要媒介分子,本试验中克隆了多子小瓜虫Ichthyoph-thirius multifiliis HSP70（Im HSP70）基因的ORF,采用荧光定量RT-PCR法,在水温为20、25、30℃的条件下检测了HSP70基因在多子小瓜虫幼虫、滋养体和包囊3个不同发育阶段的表达情况。结果表明：Im HSP70基因的ORF为1995 bp,预测编码为664 aa; Im HSP70蛋白的二级结构主要以α-螺旋和无规卷曲为主,空间构型包括N端ATPase功能域和C端多肽结合功能域;与其他物种HSP70蛋白序列进行同源性比较发现, Im HSP70与螅状独缩虫Carchesium polypinum HSP70的同源性最高,为78.08%; Im HSP70与分类地位同为纤毛门的螅状独缩虫、嗜热四膜虫Tetrahymena thermophila、变藓棘毛虫Sterkiella histriomuscorum的HSP70聚在一个分支;3种温度下幼虫的HSP70表达量均最低,20℃和25℃时, HSP70基因在滋养体中的表达量显著高于幼虫和包囊（P〈0.05）,而30℃时, HSP70基因在包囊中的表达量显著高于滋养体和幼虫（P〈0.05）;30℃时HSP70基因在包囊中的表达量显著高于25℃（P〈0.05）。研究表明,试验所用多子小瓜虫的HSP70基因在30℃时仍大量表达,且能感染试验鱼,推测该虫株为热带型多子小瓜虫, HSP70基因在多子小瓜虫对抗外界高温环境中可能发挥着重要的作用。 相似文献