中文摘要：

使用线性聚丙烯酰胺作为筛分介质，对片段长度为80-584bp的标准DNA样品进行毛细管电泳，利用激光诱导荧光方法检测信号，荧光染料为溴化乙啶。改变电场强度100-375V／cm，得到的迁移率曲线与电场强度和DNA片段长度成复杂的函数关系，已有的经典理论模型：Ogston模型、Reptation无拉伸模型和Reptation拉伸模型都不能正确地描述实验观察到的迁移率随电场强度和DNA片段长度的变化情况。因此，提出一种修正的Ogston筛分理论，假定迁移的DNA分子在电场强度方向延展拉伸，如同小分子穿过凝胶筛孔。在该修正模型中，DNA的迁移率仅依赖于电场强度、筛分介质浓度和片段长度，很好地解释了实验现象。

英文摘要：

Capillary electrophoresis of DNA fragments （ from 80 bp to 584 bp） in replaceable linear polyacryl-amide （LPA） solution was investigated using laser induced fluorescence detection. The fluorescence dye was ethidium bromide （EB）. When the electric field strength was changed from 100 V/cm to 375 V/cm, the mobility was varied as a complex function of fragment size and electric field. The classic theory models of Ogston and Reptation did not work well here. A modified Ogston model for LPA sieving medium was presented. It assumes that the applied electric field in conjunction with the gel matrix distorts the DNA, altering the effective size of the migrating molecule. The stretched DNA offers a smaller cross-section to the gel pore and thus sieves like a smaller molecule. In this model, the electrophoresis mobility depends only on the applied electric field strength, the concentration of gel matrix and the size of the fragment. The modified Ogston equation accurately predicts the mobility of DNA fragments in various electric fields, providing a single simple model to account for all of the observed behavior.