Shiokawa Koichiro, Fu Yuchang, Hosokawa Keiichi, Yamana K
Department of Biology, Faculty of Science 33, Kyushu University, 812, Fukuoka, Japan.
Department of Biochemistry, Kawasaki Medical College, 577 Matsushima, 701-01, Kurashiki, Japan.
Rouxs Arch Dev Biol. 1990 Nov;199(3):174-180. doi: 10.1007/BF01681491.
Circular and linearized plasmid DNA which contained bacterial chloramphenicol acetyltransferase (CAT) gene connected toXenopus cardiacα-actin promoter was injected intoXenopus fertilized eggs to study their expression in the course of early embryonic development. While circular DNA was slightly replicated and expressed only after embryos reached neurula stage, linearized DNA formed a large amount of concatemers, and was expressed as early as at blastula stage, or about 14 hr earlier than the time of circular DNA expression. Similarly earlier expression of linearized DNA occurred slightly more strongly when the DNA was injected into presumptive dorsal than in ventral blastomeres at 4-cell stage, and the expression was not affected when embryos were dissociated at blastula stage and their cells were cultured under reaggregating or nonreaggregating conditions. These results show that although circular actin-CAT fusion gene is expressed during development according to endogenous temporal control, the expression of linearized DNA deviates from such developmental control even though it contains intact promoter ofα-actin gene. It is then recommended that study of the control of the expression of exogenously-introduced DNA inXenopus fertilized eggs should be carried out with circular but not linearized plasmids.
将含有与非洲爪蟾心脏α-肌动蛋白启动子相连的细菌氯霉素乙酰转移酶（CAT）基因的环状和线性化质粒DNA注入非洲爪蟾受精卵中，以研究它们在早期胚胎发育过程中的表达情况。环状DNA只有在胚胎发育到神经胚阶段后才会轻微复制并表达，而线性化DNA会形成大量串联体，并早在囊胚期就开始表达，比环状DNA的表达时间早约14小时。同样，当在4细胞期将线性化DNA注入预定的背侧卵裂球时，其更早的表达会比注入腹侧卵裂球时稍微强烈一些，并且当胚胎在囊胚期解离，其细胞在重新聚集或非重新聚集条件下培养时，表达不受影响。这些结果表明，尽管环状肌动蛋白-CAT融合基因在发育过程中是根据内源性时间控制进行表达的，但线性化DNA的表达即使包含完整的α-肌动蛋白基因启动子，也偏离了这种发育控制。因此建议在非洲爪蟾受精卵中研究外源导入DNA表达的控制时，应使用环状而非线性化的质粒。
