中文摘要：

鱼精蛋白是近年发展起来的又一新型的天然高分子非病毒载体,可以作为一种良好的基因载体用作输运DNA,而它在不同体积分数乙醇溶液中也会影响其输运效果,作者利用鱼精蛋白这一性质,用单分子荧光电泳技术以及原子力显微镜探究它在不同体积分数的乙醇溶液下对DNA的凝聚效果以及DNA的电荷逆转规律的影响。单分子荧光电泳实验结果表明,DNA的电泳迁移率符号随鱼精蛋白浓度的增大由负变正,即DNA发生电荷逆转现象。溶液中乙醇的浓度越大,DNA的电泳迁移率绝对值越小。DNA的电荷逆转不仅取决于DNA的表面电荷量,可能还取决于DNA的凝聚情况,利用原子力显微镜可观察到DNA凝聚效果随着鱼精蛋白浓度的增加而增强。接着在鱼精蛋白（0.5 ng·μL-1）溶液中,加入不同体积分数的乙醇,发现乙醇会促进鱼精蛋白对DNA的凝聚作用,且凝聚效果明显。两组实验结果均表明鱼精蛋白可凝聚DNA并能使DNA发生电荷逆转,且乙醇在鱼精蛋白导致的DNA凝聚与电荷逆转过程中起着一定的作用。

英文摘要：

Protamine has been used as a new kind of natural non-viral vector and a good gene carrier in recent years,which can transport DNA. The transport effect can be affected by the volume fraction of ethanol in solution. We use this characteristic of the protamine to explore DNA condensation and DNA charge reversal rules in different volume fraction of ethanol by using single molecule fluorescence electrophoresis and atomic force microscope technique. The results of single molecule fluorescence electrophoresis experiment show that the symbols of DNA electrophoresis mobility change from negative to positive with the increase of protamine concentration. The absolute value of electrophoresis mobility decreases with the increase of volume fraction of ethanol. The charge reversal of DNA depends not only on the surface charge of DNA,but also the morphologies of the condensation of the DNA. The morphologies of DNA in different concentrations of protamine by atomic force microscope can be observed. DNA condensation is enhanced with the increase of protamine concentration. Ethanol is found to be able to promote the interaction between DNA and protamine by adding different volume fractions of ethanol to protamine（0. 5 ng·μL-1） solution. Two groups of the experimental results show that protamine condenses DNA and induces charge reversal. The ethanol plays a certain role in DNA condensation and charge reversal.