辅助性T细胞的极化与再极化

激活的ＣＤ4 辅助性Ｔ细胞 (Ｔｈｅｌｐｅｒｃｅｌｌ,Ｔｈ)分化为Ｔｈ1和Ｔｈ2亚群并分别参与不同的免疫应答。Ｔｈ1细胞产生ＩＦＮ γ、ＴＮＦ β和ＩＬ 2并促进对细胞内病原的有效免疫应答 ,但过强的应答导致自身免疫病的发生。Ｔｈ2细胞则产生ＩＬ 4、ＩＬ 5、ＩＬ 6和ＩＬ 1 3并参与清除胞外感染的病原体 ,同时也介导过敏反应。Ｔ细胞亚群的分化及细胞因子表达过程大致可以分为 3个阶段 :( 1 )起始相 ,此过程高度依赖抗原、细胞因子和细胞因子诱导的ＳＴＡＴ因子 ;( 2 )定向相 ,此阶段受亚群特异的转录因子介导 ,在Ｔｈ2细胞为ＧＡＴＡ…     

STAT的转录调控作用及其生物学效应

ＳＴＡＴ的转录调控作用及其生物学效应刘云浩倪菊华贾弘（北京医科大学生化与分子生物学系，北京１０００８３）关键词ＳＴＡＴ转录调控ＳＴＡＴ（ｓｉｇｎａｌｔｒａｎｓｄｕｃｅｒａｎｄａｃｔｉｖａｔｏｒｏｆｔｒａｎｓｃｒｉｐｔｉｏｎ）是一族ＤＮＡ结合蛋白，与...     

sIL—16结构与功能研究进展

1 .ｓＩＬ 1 6的来源与结构白细胞介素 1 6(ｉｎｔｅｒｌｅｕｋｉｎ 1 6,ＩＬ 1 6) ,又名淋巴细胞趋化因子 (ｌｙｍｐｈｏｃｙｔｅｃｈｒｏ ｍａｔａｘｉｓｆａｃｔｏｒ ,ＬＣＦ) ,是 1 982年由ＣｒｕｉｋＳｈａｎｋ实验室从抗原刺激的单核细胞中分离提纯的[1] ,主要来源于外周血单核细胞 ,它的前体由 63 1个氨基酸构成 ,无生物学活性 ,被白介素 1 β 转化酶 (ｃａｓｐａｓｅ 3 ,ｉｎｔｅｒｌｅｕｋｉｎ 1 β ｃｏｎ ｖｅｒｔｉｎｇｅｎｚｙｍｅＩＣＥ/ＣＥＤ 3 ｐｒｏｔｅａｓｅ)在Ａｓｐ5 10 和Ｓｅｒ5 11位酶切后[2 ] ,形成 1 2 1个氨基…     

TRAIL及其受体介导的信号转导通路

1 .概述新近克隆的肿瘤坏死因子ＴＮＦ(ｔｕｍｏｒｎｅｃｒｏｓｉｓｆａｃｔｏｒ,ＴＮＦ)家族新成员———肿瘤坏死因子相关的凋亡诱导配体 (ＴＮＦ ｒｅｌａｔｅｄａｐｏｐ ｔｏｓｉｓ ｉｎｄｕｃｉｎｇｌｉｇａｎｄ ,ＴＲＡＩＬ) [1] 因其结构和功能与ＴＮＦ家族的另一成员ＦａｓＬ/Ａｐｏ 1Ｌ极为相似 ,又称Ａｐｏ 2Ｌ[2 ] 。与其他所有ＴＮＦ家族成员一样 ,ＴＲＡＩＬ属Ⅱ型跨膜糖蛋白 ,Ｃ末端胞外区 ( 1 1 4～ 2 81位氨基酸残基 )含有同源三聚体亚单位 ,在溶液中可形成三聚体或二聚体。可溶性ＴＲＡＩＬ在体外和体内均可诱导多种肿瘤细…     

三叶因子3的研究

三叶因子 3 (ｔｒｅｆｏｉｌｆａｃｔｏｒ 3 ,ＴＦＦ3 )是一种胃肠道粘膜修复因子 ,1 991年在大鼠ｃＤＮＡ文库中第一次被克隆 ,它由 60个氨基酸组成 ,分子中含有 7个Ｃｙｓ ,其中有 6个Ｃｙｓ以Ｃｙｓ1 Ｃｙｓ5 、Ｃｙｓ2 Ｃｙｓ4、Ｃｙｓ3 Ｃｙｓ6 的形式构成二硫键 ,形成一个状似叶片的紧凑结构 ,因而最初命名为小肠三叶因子 (ｉｎｔｅｓｔｉｎａｌｔｒｅｆｏｉｌｆａｃ ｔｏｒ,ＩＴＦ) [1] 。哺乳动物中有 3种三叶因子 ,分别为含有一个三叶结构域的乳腺癌相关肽(ＴＦＦ1或ｐＳ2 ) ,含有两个三叶结构域的解痉挛多肽 (ＴＦＦ2或ＳＰ)以及…     

牛免疫缺陷病毒反式激活因子功能域的研究

牛免疫缺陷病毒 (Ｂｏｖｉｎｅｉｍｍｕｎｏｄｅｆｉｃｉｅｎｃｙｖｉｒｕｓ,ＢＩＶ )与人免疫缺陷病毒 (Ｈｕｍａｎｉｍ ｍｕｎｏｄｅｆｉｃｉｅｎｃｙｖｉｒｕｓ,ＨＩＶ)同属反转录病毒科慢病毒属[1] 。ＢＩＶ基因组 5′端的长末端重复序列 (ＬＴＲ)起始病毒结构基因和非结构基因的转录[2 ] ,因而许多细胞因子和病毒编码的调节蛋白作用于ＬＴＲ ,以调节ＢＩＶ的基因表达。其中Ｔａｔ蛋白是ＢＩＶ的反式激活因子 ,可大大提高ＬＴＲ的转录水平 ,在ＢＩＶ的基因表达及基因组复制的调节中起重要作用[3 ] 。ＨＩＶ、马传染性贫血病毒 (Ｅｑｕｉ…     

Isolation and mapping of bacterial artificial chromosome (BAC) clone containing telomere-associated sequence

Ｔｅｌｏｍｅｒｅｓａｒｅｔｈｅｅｎｄｓｏｆｔｈｅｅｕｋａｒｙｏｔｉｃｃｈｒｏｍｏｓｏｍｅｓａｎｄｃｏｎｓｉｓｔｏｆｔａｎｄｅｍｌｙｓｈｏｒｔｒｅｐｅａｔｓｅｑｕｅｎｃｅｓｗｈｉｃｈａｒｅｄｅｓｃｒｉｂｅｄｂｙｔｈｅｃｏｎｓｅｎｓｕｓ[ｄ(Ｔ/Ａ)14ｄＧ18]ｎｉｎｍｏｓｔｏｒｇａｎｉｓｍｓ.ＴｈｅｔｅｌｏｍｅｒｉｃｒｅｐｅａｔｓｏｆＡｒａｂｉｄｏｐｓｉｓ,[ＴＴＴＡＧＧＧ]ｎ,ｗｅｒｅｃｌｏｎｅｄｉｎ1988[1].Ｇａｎａｌｅｔａｌ.[2]ｒｅｐｏｒｔｅｄｔｈｅｔｏｍａｔｏｔｅｌｏｍｅｒｅｓｅｑｕｅｎｃｅ,[ＴＴ(Ｔ/Ａ…     

黄花川西獐牙菜的组织培养

1　植物名称　黄花川西獐牙菜 (Ｓｗｅｒｔｉａｍｕｓｓｏｔｉｉｖａｒ.ｆｌａｖｅｓｃｅｎｓ)。2　材料类别　叶、带节茎段、不带节茎段、顶芽。3　培养条件　基本培养基为ＭＳ培养基。诱导愈伤组织及芽分化培养基 :( 1 )ＭＳ ＮＡＡ 0 .0 6ｍｇ·Ｌ- 1 (单位下同 ) ＩＡＡ 0 .0 6 ＫＴ 0 .1 2 ;( 2 )ＭＳ ＮＡＡ 0 .0 6 ＩＡＡ 0 .0 6 ＫＴ 0 .2 ;( 3)ＭＳ ＮＡＡ0 .0 6 ＩＡＡ 0 .0 6 ＫＴ 0 .3;( 4 )ＭＳ ＮＡＡ 0 .0 6 ＩＡＡ 0 .0 6 ＫＴ 0 .4;( 5 )ＭＳ ＮＡＡ 0 .1 ＩＡＡ 0 .1 ＫＴ 1 .0。生根培养基 :( 6) 1 /2ＭＳ ;( 7) …     

玉叶金花的组织培养和植株再生

1　植物名称　玉叶金花 (Ｍｕｓｓａｅｎｄａｐｕｂｅｓｃｅｎｓ)。2　材料类别　嫩茎、幼叶。3　培养条件　以ＭＳ为基本培养基。诱导愈伤组织附加 :( 1 )ＮＡＡ 0 .2ｍｇ·Ｌ- 1 (单位下同 ) ＫＴ0 .2 5 6 ＢＡ 0 .1 ;( 2 )ＮＡＡ 0 .5 ＫＴ 0 .2 5 6 ＢＡ0 .1 ;( 3)ＮＡＡ 0 .5 6 ＢＡ 0 .1 ;( 4 ) 2 ,4 Ｄ 0 .2 ＫＴ0 .1。继代培养基附加 :( 5 ) 6 ＢＡ 4 ＫＴ0 .2 5 ＩＡＡ 0 .5。不定芽诱导及增殖培养基附加 :( 6)6 ＢＡ 4 ＫＴ 0 .5 ＩＡＡ 0 .1。生根培养基 :( 7)1 /2ＭＳ ＩＢＡ 0 .5。上述培养基均含 0 .7%琼脂、3%蔗…     

一类新型转录因子家族：信号转导剂和转录激活剂

信号转导剂和转录激活剂（ＳＴＡＴ）是近三四年才发现的一类新型转录因子家族。许多配体,尤其是细胞因子,能使ＳＴＡＴ的酪氨酶磷酸化而激活。激活的ＳＴＡＴ蛋白能形成同二聚体和异二聚体,进入细胞核内结合ＤＮＡ序列,调节多个基因表达。这些既在胞浆里起信号转导作用又在胞核内起激活转录作用的双功能蛋白质的发现,为细胞因子信号转导路通研究揭开了新的一页。     

壳聚糖酶的克隆表达与壳寡糖的制备分析

目的:克隆壳聚糖酶基因于大肠杆菌中实现高表达,制备壳寡糖。方法:以枯草芽孢杆菌总DNA为模板扩增壳聚糖酶基因(CSN),克隆至载体pET23a(+)上,转化菌株BL21(DE3)。重组子经0.5 mmol/L IPTG诱导后,SDS-PAGE和质谱检测与鉴定重组酶。酶纯化后水解壳聚糖,薄层色谱分析其水解产物。结果:质谱证明壳聚糖酶(31.5kDa)成功表达,表达量占菌体总蛋白的45%左右。纯化后重组酶浓度为900 mg/L,纯度95%、回收率85%,酶活力为10 000 U/mg。壳聚糖降解产物为壳二糖至壳四糖。结论:原核表达载体pET23a(+)-CSN构建正确,壳聚糖酶表达量与活性高,适用于水解壳聚糖制备壳寡糖。     

国内外蝗害治理技术现状与展望

本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...     

Molecular characterisation of species and genotypes of Cryptosporidium and Giardia and assessment of zoonotic transmission

The molecular characterisation of species and genotypes of Cryptosporidium and Giardia is essential for accurately identifying organisms and assessing zoonotic transmission. Results of recent molecular epidemiological studies strongly suggest that zoonotic transmission plays an important role in cryptosporidiosis epidemiology. In such cases the most prevalent zoonotic species is Cryptosporidium parvum. Genotyping and subtyping data suggest that zoonotic transmission is not as prevalent in the epidemiology of giardiasis. Molecular characterisation of Cryptosporidium and Giardia is a relatively recent application that is evolving as new genes are found that increase the accuracy of identification while discovering a greater diversity of species and yet unnamed taxa within these two important genera. As molecular data accumulate, our understanding of the role of zoonotic transmission in epidemiology and clinical manifestations is becoming clearer.     

Synthesis and turnover of cerebrosides and phosphatidylserine of myelin and microsomal fractions of adult and developing rat brain.

The synthesis and turnover of cerebrosides and phospholipids was followed in microsomal and myelin fractions of developing and adult rat brains after an intracerebral injection of [U-14C]serine. The kinetics of incorporation of radioactivity into microsomal and myelin cerebrosides indicate the possibility of a precursor-product relationship between cerebrosides of these membranes. The specific radioactivity of myelin cerebrosides was corrected for the deposition of newly formed cerebrosides in myelin. Multiphasic curves were obtained for the decline in specific radioactivity of myelin and microsomal cerebrosides, suggesting different cerebroside pools in these membranes. The half-life of the fast turning-over pool of cerebrosides of myelin was 7 and 22 days for the developing and adult rat brain respectively. The half-life of the slowly turning-over pool of myelin cerebrosides was about 145 days for both groups of animals. The half-life of the rapidly turning-over microsomal cerebrosides was calculated to be 20 and 40 h for the developing and adult animals respectively. The half-life of the intermediate and slowly turning-over microsomal cerebrosides was 11 and 60 days respectively, for both groups of animals. The amount of incorporation of radioactivity into microsomal cerebrosides from L-serine was greatly decreased in the adult animals, and greater amounts of the precursor were directed towards the synthesis of phosphatidylserine. In the developing animals, considerable amounts of cerebrosides were synthesized from L-serine, besides phosphatidylserine. The time-course of incorporation indicated that a precursor-product relationship exists between microsomal and myelin phosphatidylserine. The half-life of microsomal phosphatidylserine was calculated to be about 8 h for the fast turning-over pool in both groups of animals.     

Identification and composition of the tonsillar and anal enterococcal and streptococcal flora of dogs and cats

Enterococcus faecalis was the most frequently isolated enterococcal species from anal swabs and tonsils of dogs and cats, although in the anal samples from dogs Ent. hirae was found almost as often as Ent. faecalis. Most Ent.faecium strains from dog tonsils differed from those associated with humans and other animals in that they fermented sorbitol. Typical Ent. avium as well as atypical Ent. avium -like strains were seen in dogs, while the related species Ent. raffinosus was associated with cat tonsils. Enterococcus cecorum also occurred mainly in cats. Certain atypical strains, presumptively identified as Ent. cecorum , shared characteristics with Ent. columbae.
The most frequent streptococcal species in tonsils of cats and dogs were Streptococcus suis and Strep. canis. Streptococcus canis and Strep. bovis predominated in anal swabs. The canine Strep. suis differed from the common porcine strains in fermenting mannitol.
Forty-seven of the 288 isolates examined could not be identified or related to known species. The characteristics of two groups of these bacteria, provisionally called 'Ton 31 group' and 'O7 group' are described.     

Coiled-coil nanomechanics and uncoiling and unfolding of the superhelix and alpha-helices of myosin

The nanomechanical properties of the coiled-coils of myosin are fundamentally important in understanding muscle assembly and contraction. Force spectra of single molecules of double-headed myosin, single-headed myosin, and coiled-coil tail fragments were acquired with an atomic force microscope and displayed characteristic triphasic force-distance responses to stretch: a rise phase (R) and a plateau phase (P) and an exponential phase (E). The R and P phases arise mainly from the stretching of the coiled-coils, with the hinge region being the main contributor to the rise phase at low force. Only the E phase was analyzable by the worm-like chain model of polymer elasticity. Restrained molecular mechanics simulations on an existing x-ray structure of scallop S2 yielded force spectra with either two or three phases, depending on the mode of stretch. It revealed that coiled-coil chains separate completely near the end of the P phase and the stretching of the unfolded chains gives rise to the E phase. Extensive conformational searching yielded a P phase force near 40 pN that agreed well with the experimental value. We suggest that the flexible and elastic S2 region, particularly the hinge region, may undergo force-induced unfolding and extend reversibly during actomyosin powerstroke.     

Carnitine and creatine content of tissues of normal and alloxan-diabetic sheep and rats

The concentration of carnitine in liver increased 28-fold and urinary carnitine excretion 5-fold in alloxan-diabetic sheep. In contrast there were no similar increases in alloxan-diabetic rats. The creatine content of liver decreased 3-fold and creatine excretion decreased 2-fold in diabetic sheep. In contrast the creatine content of liver increased nearly 4-fold in diabetic rats with no change in creatine excretion. The marked increased in production of carnitine by the liver of the diabetic sheep appears possible because of decreased production and excretion of creatine.