青鳉鱼早期胚胎中外源DNA的复制行为的研究

利用显微注射技术将外源ＤＮＡ与标有生物素的ｄＡＴＰ一起导入处于１细胞期的青鱼（Ｍｅｄａｋａ）受精卵细胞质中，鱼卵在２５℃孵化一天至胚孔封闭期，从胚胎细胞质中提取ＤＮＡ，经分子杂交发现外源ＤＮＡ在胚胎中可进行复制。ＤＮＡ样品再经核酸电镜分析，发现了几种类型的复制分子，并发现多复制叉及成熟前复制现象。由此认为外源ＤＮＡ可以多种方式在青鱼早期胚胎细胞质中进行复制。

Behavior of foreign DNA in early Medaka embryo

Purified plasmid PSMGH and PBR322 (circular or linear ) were coinjectedwith biotinylated dATP into fertilized eggs of Medaka fish at the one cell stage. The injected eggs were kept at 25C to the stage of blastpore closure. Then DNA was extracted from cytoplasm of the embryonic cells and analyzed. Newly synthesized biotinylatedDNA was found in cytoplasm. No detectable biotinylated DNA was found in the cytoplasm of the controls, into which only biotinylated dATP was injected. The DNA sample from the cytoplasm, into which PSMGHDNA was injected, was applied to transmission electron microscopy investigation. Some types of replicating molecules were found,including the Y,B and rolling circle forms. The premature and poly fork replications werealso found.