Dengue virus 2 capsid protein chaperones the strand displacement of 5′-3′ cyclization sequences

By virtue of its chaperone activity, the capsid protein of dengue virus strain 2 (DENV2C) promotes nucleic acid structural rearrangements. However, the role of DENV2C during the interaction of RNA elements involved in stabilizing the 5′-3′ panhandle structure of DENV RNA is still unclear. Therefore, we determined how DENV2C affects structural functionality of the capsid-coding region hairpin element (cHP) during annealing and strand displacement of the 9-nt cyclization sequence (5CS) and its complementary 3CS. cHP has two distinct functions: a role in translation start codon selection and a role in RNA synthesis. Our results showed that cHP impedes annealing between 5CS and 3CS. Although DENV2C does not modulate structural functionality of cHP, it accelerates annealing and specifically promotes strand displacement of 3CS during 5′-3′ panhandle formation. Furthermore, DENV2C exerts its chaperone activity by favouring one of the active conformations of cHP. Based on our results, we propose mechanisms for annealing and strand displacement involving cHP. Thus, our results provide mechanistic insights into how DENV2C regulates RNA synthesis by modulating essential RNA elements in the capsid-coding region, that in turn allow for DENV replication.     

S-腺苷甲硫氨酸的研究现状及应用前景

介绍了S-腺苷甲硫氨酸的制备方法及稳定性研究现状,并对其临床应用及市场前景进行了分析。     

急性髓系白血病患者NF-κB p65和β-Catenin蛋白表达的临床研究

目的探讨NF-κB p65和β-catenin在急性髓系白血病(AML)患者中表达的临床意义及判断预后价值.方法 28例患者均进行6个以上疗程的化疗,应用免疫组织化学SABC法和图像分析系统对AML患者治疗前后骨髓细胞NF-κB p65和β-catenin进行了检测.结果 NF-κB p65和β-catenin在AML患者骨髓单个核细胞的胞质和胞核中表达,完全缓解和部分缓解患者在化疗后二者表达明显降低(P<0.05),未缓解组治疗前后无明显变化.结论 NF-κB p65和β-catenin表达与AML患者的化疗效果及预后有直接的联系,NF-κB p65和β-catenin共同表达情况可作为预测AML患者化疗敏感性的指标.     

巴戟天挥发性成分研究

目的：研究巴戟天中的挥发性成分。方法：利用水蒸气蒸馏法提取巴戟天（Radix morindae offtcinalis）挥发油,用GC—MS进行测定,结合计算机检索技术对分离的化合物进行结构鉴定,应用色谱峰面积归一化法计算各成分的相对百分含量。结果：鉴定出34个化学成分,其中相对百分含量大于2％的分别确定为L-龙脑（Bomeol L）29．28％,α-姜烯（Alpha—Zingiberene）4．88％,2-甲基-6-对甲基苯基-2-庚烯（Ar-Cureumene）4．49％,1-己醇（1-Hexanol）3．40％,β-倍半水芹烯（beta—sesquiphellandrene）3．34％,2-戊基呋喃（2-Amylfuran）3．32％,正壬醛（n—nonanal）2．17％,樟脑（L—camphor）2．07％,β-没药烯（bete—Bisabolene）2．06％。结论：34个挥发性成分均为首次从该植物中得到。     

人抑癌基因PTEN的原核表达载体的构建及融合表达

为研究抑癌因子PTEN蛋白的抑癌机理,掏建了PTEN cDNA的原核表达载体并进行融合表达。将含有PTEN cDNA的质粒pMD-PTEN经EcoR Ⅰ和Sal Ⅰ双酶切,回收PTEN基因片段与经相同酶切的高效原核表达载体pET-44a连接,经序列测定,证实融合型表达载体pET-Nus-PTEN构建成功。转化表达宿主BL21(DE3)后,IPTG诱导表达。经12％SDS-PAGE凝胶电泳,获得118kD的特异蛋白条带。目的蛋白占细菌总蛋白的17％。结果表明：PTEN基因和Nus基因融合表达成功,获得可溶性Nus-PTEN蛋白。该研究为PTEN蛋白的抑癌机理和基因工程药物的研究打下了基础,这是国内PTEN蛋白在原核细胞中成功表达的首次报道。     

ω-6脂肪酸脱氢酶基因在乳腺癌细胞内的表达和作用

为探讨ω- 6脂肪酸脱氢酶基因fat -1在人类乳腺癌细胞MCF- 7中表达和对其生长的作用,将fat -1基因插入到腺病毒载体中,构建腺病毒重组载体(Ad·GFP·fat1) .通过包装细胞系(2 93)产生重组腺病毒,感染MCF 7细胞.用核糖核酸酶保护性分析技术,检测fat -1基因在MCF- 7细胞内的表达,细胞增殖试剂盒(MTT)和凋亡染色试剂盒染色分析fat 1基因对MCF- 7细胞增殖和凋亡的影响,用酶联免疫分析花生酸类(eicosanoids)前列腺素E2 (prostaglandinE2 )的含量.结果显示,腺病毒介导的fat- 1基因能在MCF- 7细胞内有效异源表达,抑制MCF -7细胞的增殖且导致凋亡,前列腺素的含量也明显地减少.结果说明,fat- 1基因在乳腺癌的基因治疗中具有良好利用价值.     

东亚钳蝎氯毒素BmKCT的表达和功能鉴定(英文)

从中国东亚钳蝎ButhusmartensiiKarsch的毒腺cDNA文库中分离得到了一个编码毒素蛋白多肽 (命名为BmKCT)前体的全长cDNA序列 .该毒素多肽与已报道的氯毒素 (chlorotoxin)高度同源 ,其蛋白质一级序列有 6 8%的同源性 .为了鉴定BmKCT的生物学功能 ,通过pGEX系统成功地表达了BmKCT ,并用GST亲和层析和凝胶过滤的方法获得了纯化的重组BmKCT毒素蛋白 (rBmKCT) .通过膜片钳实验 ,记录了rBmKCT对人脑星型胶质瘤细胞 (gliomascell)表面的氯离子通道电流的作用 .结果显示 ,BmKCT可以显著抑制人脑星型胶质瘤细胞表面的氯离子通道电流 ,并且这种抑制作用在一定程度上是可逆的 .实验证明 ,在细胞水平上 ,BmKCT是一种新的短链氯离子通道抑制剂 .     

酵母双杂交技术研究与人孕酮受体B相互作用的蛋白质

应用酵母双杂交技术研究与人孕酮受体B（hPRB）发生相互作用的蛋白质,有助于进一步阐明其在乳腺癌的发生发展中发挥重要作用的调控机制。应用酵母双杂交系统3,以hPRB不同结构域为诱饵,筛选人乳腺cDNA文库,寻找能与之相互作用的蛋白质,并运用X—α—Gal等实验提供的信息,筛除假阳性克隆。最终以AF1-DBD结构域作为诱饵最终筛出了1个阳性克隆,经测序及生物信息学分析,这个克隆所编码的蛋白为PIAS3（活化的STAT3的蛋白抑制剂）。结果表明,孕激素受体可以和PIAS3发生相互作用,它们的相互作用有可能参与乳腺癌的生长调控。     

猪卵巢体外保存温度对卵母细胞染色质构型和成熟能力的影响

Most porcine oocytes used in studies on embryo biotechnology and the in vitro production of embryos are currently obtained from the ovaries of slaughtered gilts. The duration and temperature during ovary transportation and handling might, therefore, affect the recovery of culturable COCs, chromatin configuration and developmental competence of oocytes. The effects of ovary storage temperature on chromatin configuration and in vitro maturation of porcine oocytes were examined in this study. Ovaries collected from a slaughterhouse were stored in vitro for 8 h under different temperatures. The results showed that more culturable COCs were isolated from the ovares stored at 39℃ than that from ovaries stored at 31℃ or 20℃ and before storage. Thirty-one centidegree was the best storage temperature in terms of cumulus expansion, nuclear maturation and morphology of the first polar body after in vitro maturation culture. The ability of cumulus expansion was completely lost in COCs derived from ovaries stored at 39℃ for 8 hours. Ovary storage （at both 31℃ and at 20℃ ） increased the proportion of oocytes with the GVc configuration in which chromatin condensed into a single big clump at the nucleolus and the functional significance of this configuration needs further investigations [ Acta Zoologica Sinica 51 （5）： 919 923, 2005].