用物理学技术研究细胞的分子力学特征

运动对于细胞生命活动的重要性是不言而喻的。有运动就需要有推动运动的力。长期以来,由于缺少对大分子间作用力的研究手段,生物学家们对生物学过程中分子力学现象的了解极为有限。近年来,多种物理学技术迅速发展,并应用于生物学领域,尤其是细胞骨架系统,有力地推动了从力学角度对很多生命现象和机理的研究。本文将简单介绍几种目前常用于测定细胞分子力学特征的物理学技术及一些它们在这方面的研究实例;着重介绍光学测力技术中目前最为成熟的一种技术-光钳,以及它在研究细胞骨架分子力学特征方面的应用。     

Application of the S-score algorithm for analysis of oligonucleotide microarrays

In the past several years, oligonucleotide microarrays have emerged as a widely used tool for the simultaneous, non-biased measurement of expression levels for thousands of genes. Several challenges exist in successfully utilizing this biotechnology; principal among these is analysis of microarray data. An experiment to measure differential gene expression can consist of a dozen microarrays, each consisting of over a hundred thousand data points. Previously, we have described the use of a novel algorithm for analyzing oligonucleotide microarrays and assessing changes in gene expression [J. Mol. Biol. 317 (2002) 225]. This algorithm describes changes in expression in terms of the statistical significance (S-score) of change, which combines signals detected by multiple probe pairs according to an error model characteristic of oligonucleotide arrays. Software is available that simplifies the use of the application of this algorithm so that it may be applied to improving the analysis of oligonucleotide microarray data. The application of this method to problems of the central nervous system is discussed.     

罗伯逊易位群体遗传结构的DNA指纹分析

用微卫星探针（GGAT）4得到了罗伯逊易位猪群体内共9个家猪品种的DNA指纹图。1－9品种依次为：13／17罗伯逊易位纯合子猪群体、13／17罗伯逊易位杂合子猪群体、13／17罗伯逊易位杂合子猪互交所得到的正常核型猪群体（杂交0号）、丹系长白猪群体、加系双肌臂杜洛克猪群体、加系双肌臀大约克猪群体、加系双肌臀长白猪群体、丹系长白猪与13／17易位杂合子猪产生的杂交后备猪群体（杂交1号）、杜洛克猪与13／17易位杂合子猪产生的杂交后备猪群体（杂交2号）。根据指纹带型计算了每个群体的相似系数（F）、平均等位基因频率（Q）、最底平均杂合率（H）和遗传距离指数（D）。9个品种的相似系数介于0．546－0．931,根据各品种之间的遗传距离指数作出矩阵图,并据此绘制出品种间亲缘关系树状聚类图。     

现代生物技术在环境微生物学中的应用:I.基因探针和探针探测

现代生物技术在环境微生物学中的应用将发表系列综述文章。第一篇讨论基因探针和探针探测。这篇文章包含菌落转移或菌落杂交 ,Southern杂交和Northern杂交以及生物芯片。     

大肠杆菌O157:H7核酸探针检测方法的建立

目的：应用核酸探针方法快速检测大肠杆菌O157：H7。方法：通过使用吖啶酯标记的特异DNA探针方法检测大肠杆菌O157：H7,对此种方法的特异性、敏感性、准确性进行研究,比较该方法与传统国标法的检测结果。结果：核酸探针方法检测大肠杆菌O157：H7特异性以及敏感性强,检出大肠杆菌O157：H7菌液浓度最低限约为106cfu/ml,检测大肠杆菌O157：H7的结果与国标法相一致;对O157：H7鉴定时间仅需30min,简便快捷。结论：核酸探针方法可用于大肠杆菌O157：H7的快速检测。     

纳米金探针在基因检测中的应用

传统的核酸分析中常采用放射性元素、荧光色素以及酶标记等基因探针,这些探针都存在着一些不足之处。近年来,纳米金探针作为一种新型的基因探针,己引起了广泛的关注。该探针具有优良的光谱特征和光化学稳定性,对核酸的非特异吸附性小,与核酸等生物大分子结合后不改变生物分子的活性。将纳米金探针用于基因检测,具有操作简便、快速、安全、实验成本低等优点。本文就纳米金探针的发展过程、纳米金探针的制备、检测原理及其在基因分析中的应用等几个方面作了系统而全面地概述,同时介绍了纳米金探针的最新研究进展,并对其发展前景作了简要评述。     

Stable Triple-Stranded DNA Formation and its Application to the SNP Detection

We have found that a short stretch (30mer or larger) of triple-strandedDNA structure formed at the terminus (or very near) of linearDNA molecules is unusually stable, withstanding heat treatmentat as high as 95°C. The stable triple-stranded structureis formed only when deoxyoligonucleotides are complementaryto the strand terminating with 5'-phosphate and not to the strandterminating with 3'-OH. Presence of a single mismatched basein the complementary deoxyoligonucleotides drastically reducesthe stability. We show that these unique properties of the terminaltriple-stranded structure can be applied to the detection ofsingle nucleotide polymorphisms in genomes without DNA dissociationand/or hybridization.     

Improved measurement of dibenzo[a,l]pyrene-induced abasic sites by the aldehyde-reactive probe assay

Dibenzo[a,l]pyrene (DB[a,l]P) induces abundant amounts of depurinating adducts that spontaneously dissociate to form abasic sites in DNA. However, several previous studies that used the aldehyde-reactive probe (ARP) assay, could not verify abasic site formation by DB[a,l]P. Therefore, we examined whether a modification of the ARP assay would allow greater quantification of abasic sites. A previous study indicated that the abasic site quantification is improved by letting ARP trap the nascent abasic sites in cells, before extracting DNA for the assay. To test whether the addition of ARP to the DB[a,l]P–DNA adduct-forming reaction would improve abasic site quantification, we treated calf thymus DNA (0.625 mg/mL) with DB[a,l]P (80 μM) and 3-methylcholanthrene-treated rat liver microsomes with or without ARP (3 mM). The inclusion of ARP in the adduct-forming reaction resulted in significantly greater detection of abasic sites (62 lesions/10⁶ bp versus 3.7 lesions/10⁶ bp). DB[a,l]P also induces DNA strand breaks. The strand breaks may occur at abasic sites and by other mechanisms, such as oxidative damage. ARP/O-methoxyamine-abasic site conjugates are refractory to strand breakage, however, ARP or O-methoxyamine (3–10 mM) could only partially protect DB[a,l]P-induced DNA degradation, presumably by protecting the abasic sites, but not the other strand breaks. These results suggest that if DNA strand breakages occur at the abasic sites or at bases flanking them, and the fragments are lost during DNA extraction, abasic site estimation could be compromised. To obtain an independent line of evidence for abasic site formation in DB[a,l]P-treated cells, mouse Mβ16 fibroblasts were treated with DB[a,l]P and O-methoxyamine. O-Methoxyamine is known to potentiate cytotoxicity of abasic site-inducing chemicals by forming abasic site conjugates, which partially inhibits their repair. O-Methoxyamine was found to increase DB[a,l]P cytotoxicity in these cells, supporting the idea that DB[a,l]P formed abasic sites. In summary, the inclusion of ARP in the DB[a,l]P–DNA adduct-forming reaction traps and protects the nascent abasic sites, allowing an improved quantification of abasic sites.     

pH敏感纳米粒的制备和功能表征

目的:制备具有pH响应的甲氧基聚乙二醇甲基丙烯酸-2-六亚甲基亚胺乙酯聚合物,测试材料pH功能响应,以及建立聚合物纳米粒载药方法。方法:通过核磁共振氢谱鉴定ATRP(Atom Transfer Radical Polymerization)聚合反应所获得的化合物结构。滴加-搅拌挥发法制备聚乙二醇甲基丙烯酸-2-六亚甲基亚胺乙酯纳米粒,酶标仪测定其载药量和包封率。透射电镜下观察其形态,激光粒度仪分析测定其粒径,包载DiR红外荧光探针检测纳米粒pH响应功能。结果:分别成功合成得到2-溴代异丁酸聚乙二醇单甲醚和甲基丙烯酸-2-六亚甲基亚胺乙酯单体。通过ATRP聚合反应成功合成聚乙二醇甲基丙烯酸-2-六亚甲基亚胺乙酯聚合物材料,并通过核磁氢谱对聚合材料进行鉴定。通过滴加搅拌法制备包载有模型药物香豆素-6的纳米粒,并对纳米粒的形态表征及载药量进行测定。结论:试验结果表明制备得到的聚合物纳米粒尺寸均匀,具有预期的pH响应效果,可以装载模型药物。