Minimal sequence requirement of thrombin receptor agonist peptide.

A site-specific proteolytically generated neoamino terminus of the thrombin receptor having a sequence SFLLRNPNDKYEPF- has been reported to be a functional ligand of the receptor. This discovery raises question on the precise structural requirements of the "tethered ligand" responsible for receptor activation and signal transduction. By examining the agonist activity of a panel of synthetic sequence analogues of thrombin receptor agonist peptides (TRAP) on human platelet aggregation, we determined that the minimal sequence of the human platelet thrombin receptor ligand is SFLL-amide (TRAP1-4, EC50 = 300 uM). An extension of TRAP1-4 by an additional Arg-Asn segment yielded the most potent agonist among the series (TRAP1-6, EC50 = 1.3 microM). Based on the structure-activity relationships, we hypothesized a model of the ligand-binding site of the human platelet thrombin receptor that accommodates a hexapeptide structure. TRAP1-6, when administered intravenously, induced marked intravascular platelet aggregation in the anesthetized guinea pigs.     

家兔脊髓蛛网膜下腔注射乙酰胆碱对血压和心率的影响

将乙酰胆碱(ACh)注入麻醉家兔脊髓蛛网膜下腔,观察其对心血管活动的影响。结果表明:(1)脊髓蛛网膜下腔注射50～100μg ACh可使血压下降,心率减慢;(2)预先由脊髓蛛网膜下腔注射阿托品,可阻断ACh引起的降压和降心率作用;(3)脊髓蛛网膜下腔注射六甲双铵、酚妥拉明或心得安均不能阻断上述ACh的心血管反应;(4)切断两侧颈部迷走神经,ACh不再使心率减慢,但其降低血压的作用不受到任何影响。 脊髓中ACh水平升高可通过激活胆碱能M-受体引起血压下降和心率减慢。ACh的这种降压作用既没有中枢肾上腺素能受体活动参与,也不是通过迷走神经实现的,可能是由于脊髓交感血管中枢紧张性降低所造成的。     

两组不同月龄小鼠学习记忆能力与脑突触体内游离[Ca^2＋]i的相关性

本文采用Ｙ－迷宫和一次被动回避反应模型,观察了１,６月龄小鼠的学习记忆行为,并运用Ｃａ~（２＋）的荧光探针和ＡＲ－ＣＭ－ＭＩＣ阳离子测定系统,检测了两组小鼠四个主要脑区（海马、皮层、小脑、中脑四叠体）突触体内游离钙离子浓度（［Ｃａ~（２＋）］_ｉ）的变化。结果表明随着年龄的增长,小鼠的分辨学习及记忆能力均下降,同时海马突触体内游离［Ｃａ~（２＋）］_ｉ升高显著。     

小麦×玉米杂交后代的蛋白质及酯酶同工酶分析

以８ 个普通小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍ Ｌ．）品种为母本,２ 个栽培玉米（Ｚｅａ ｍ ａｙｓ Ｌ．）品种为父本杂交所获得的Ｆ２ 代在形态上出现了明显变异。对其籽粒进行蛋白质电泳分析,得到了如下主要结果：杂交后代的蛋白质谱带较母本有了很大的变异,主要集中在高分子量麦谷蛋白（ＨＭＷ－Ｇｌｕ）区域。杂交后代的蛋白质谱带由５ 种类型构成：１．母本型,占全部测试籽粒的２２．６％ ;２．附加型,占１４．３％ ;３．互补型,占１５．５％ ;４．杂种型,占３０．９％ ;５．缺失型,占１６．７％ 。对“矮杆早”ד紫粘”的Ｆ２ 代籽粒进行酯酶同工酶电泳分析发现,变异主要发生在ＥＳＴ－１ 区。由此看来,小麦×玉米的杂合子中玉米染色体在被排除前后,可以诱发小麦染色体组发生遗传变异     

从玉米胚中大量制备植物钙调素

从每公斤萌发２４ｈ的玉米胚丙酮粉中可提纯得６３ｍｇ的钙调素（ＣａＭ）,这是目前从每公斤植物材料中所提纯得ＣａＭ的最高记录。对其理化性质的研究表明,玉米胚ＣａＭ 有较高的生物学活性,能较好地激活磷酸二酯酶,其紫色吸收光谱,ＳＤＳ－ＰＡＧＥ电泳行为及氨基酸组成与其它的植物ＣａＭ相似。上述结果表明玉米胚是１个提取植物ＣａＭ相似。上述结果表明玉米胚是１个提取植物ＣａＭ的适宜材料。     

Human neurotrophin-3: A one-step peptide mapping method and complete disulfide characterization of the recombinant protein

Human neurotrophin-3 (NT-3) is a member of the nerve growth factor (NGF) family of neurotrophic factors, and the recombinant protein is being developed as a therapeutic for neurodegenerative diseases. The final product purity and lot-to-lot variation are monitored routinely by peptide mapping. However, only the N-terminal region of NT-3 was susceptible to proteolysis under native conditions. Complete digestion required that the protein be chemically modified by reduction and S-alkylation prior to proteolysis. Complete proteolytic degradation of the protein was achieved simply by an intial denaturation of NT-3 in 6 M guanidinium chloride (pH 6) for 2 hr at 37°C, followed by a tenfold dilution with the digestion buffer (0.1 M Tris-HCl, 1 mM CaCl₂ at pH 7.0) and immediate addition of chymotrypsin at 1% by weight. Direct comparison of the peptide map with an identical aliquot that had been reduced and alkylated also allowed the establishment of the cystine linkages present in NT-3: Cys¹⁴ to Cys⁷⁹, Cys⁵⁷ to Cys¹⁰⁸, and Cys⁶⁷ to Cys¹¹⁰. This disulfide structure is homologous to the NGF family of neurotrophic factors.     

二核苷酸重复多态性的非同位素检测及其在基因诊断中的应用

本文报道了一种检测二核苷酸重复多态性的简便的非同位素法,利用重复序列两侧的特异引物进行ＰＣＲ扩增,产生的等位片段在薄层变性聚丙烯酰胺凝胶电泳上分离,再用灵敏的银染法显色。该方法不需要标记ＰＣＲ产物,简便、快速,分辨率可达１ｂｐ,并可用多对引物同时进行多重ＰＣＲ分析。用此方法对ＤＭＤ家系成员ｄｙｓｔｒｏｐｈｉｎ基因的５＇－脑型外显子止游区和３＇－非翻译区的两个（ＣＡ）。位点进行了扩增片段长度多态性分     

表达HSV－2 gD基因的重组痘苗病毒保护小鼠对抗致死量HSV病霉攻击

利用ＰＣＲ方法对单纯疱疹病毒Ⅱ型糖蛋白Ｄ（ＨＳＶ－２ｇＤ）基因进行了修饰,在其５＇端删去约５００ｂｐ的非编码区,仅保留ＡＴＧ上游７个ｂｐ。将修饰后的ＨＳＶ－２ｇＤ基因插入到带有痘苗病毒天坛株ＴＫ基因区段的痘苗表达质粒ｐＪＳＡ１１７５,置于痘苗病毒Ｐ７．５ｋ早／晚期启动子控制下。将此重组质粒用脂质体Ｌｉｐｏｆｅｃｔｉｎ方法转染已受野型ＴＫ￣＋痘苗病毒天坛株感染的ＴＫ￣－１４３细胞,通过同源重组机制和标志基因ＬａｃＺ产物的蓝斑显色作用,以及ＢｕｄＲ试剂对ＴＫ表型的选择压力,筛选出整合有ＨＳＶ－２ｇＤ基因的重组痘苗病毒。Ｓｏｕｔｈｅｍ杂交表明,ＨＳＶ－２ｇＤ基因已正确地插入痘苗病毒ＴＫ基因区内;间接免疫荧光检测显示,ＨＳＶ－２ｇＤ蛋白已得到有效表达,且主要分布于细胞膜。重组病毒免疫家兔可产生明显的抗ＨＳＶ－２ｇＤ中和抗体。用重组病毒免疫小鼠,３周后可使９４％（１７／１８）的小鼠对抗ＨＳＶ－２的致死量攻击,表明重组病毒具有明显的免疫保护作用。     

酪氨酸羟化酶基因载体－pCMVTH 质粒的构建及在大鼠骨骼肌内的表达

为用转基因方法治疗巴金森氏病大鼠模型,本研究采用分子克隆技术,将合成多巴胺的关键酶－酪氨酸羟化酶（ＴＨ）的基因,克隆进入以巨细胞病毒ＣＭＶ为启动子的载体质粒内,经限制性内切酶定位分析证实该重组的ＤＮＡ质粒的可靠性。携带ＴＨ基因的ＰＣＭＶＴＨ质粒以ＬＩＰＯ－ＦＥＣＴＩＮ介导,在培养的原代骨骼肌细胞中高效表达。本研究为进一步用转基因的细胞植入脑内以治疗巴金森氏病打下一定基础。     

Bi（Ⅲ）与金属硫蛋白作用性质研究

 Ｂｉ（Ⅲ）与金属硫蛋白作用性质研究张保林,黄辉,朱凌燕,岳晟,唐雯霞（南京大学配位化学研究所,配位化学国家重点实验室,南京２１００９３）如何降低顺铂或其它抗癌铂的毒性,一直是癌症化疗中的重要课题之一,最近研究发现预先给大鼠或肺癌病人服用铋盐,可以极大...