Etkin L D, Pearman B
Department of Genetics, University of Texas M.D. Anderson Hospital and Tumor Institute, Houston 77030.
Development. 1987 Jan;99(1):15-23. doi: 10.1242/dev.99.1.15.
We analysed the fate, expression and germ line transmission of exogenous DNA which was microinjected into fertilized eggs of Xenopus laevis. DNA was injected into fertilized eggs within 1 h following fertilization. The injected DNA was dispersed around the site of injection and became localized to cleavage nuclei by stage 6. Injected DNA persisted in the tissues of 6- to 8-month-old frogs and exhibited a mosaic pattern of distribution with regard to the presence or absence and copy number between different tissues. We detected the exogenous DNA sequences in 60% of injected frogs. Restriction digestion analysis of this DNA suggested that it is not rearranged and was organized as head-to-tail multimers. The copy number varied from 2 to 30 copies/cell in various tissues of the same frog. Plasmid pSV2CAT which contains the prokaryotic gene coding for chloramphenicol acetyl transferase (CAT) enzyme linked to the SV40 early gene promoter was expressed in 50% of the animals containing the gene. The pattern of expression, however, varied between different animals and could not be correlated with copy number. We also showed that the exogenous DNA sequences were transmitted through the male germ line and that each offspring contained the gene integrated into a different region of the genome.
我们分析了显微注射到非洲爪蟾受精卵中的外源DNA的命运、表达及种系传递情况。在受精后1小时内将DNA注射到受精卵中。注射的DNA分散在注射部位周围，并在6期定位于分裂细胞核。注射的DNA在6至8月龄青蛙的组织中持续存在，并且在不同组织之间关于存在与否及拷贝数呈现镶嵌分布模式。我们在60%的注射青蛙中检测到了外源DNA序列。对该DNA的限制性消化分析表明它未重排，而是以头对头多聚体形式存在。在同一只青蛙的不同组织中，拷贝数从2到30个拷贝/细胞不等。含有与SV40早期基因启动子相连的编码氯霉素乙酰转移酶（CAT）的原核基因的质粒pSV2CAT在50%含有该基因的动物中表达。然而，表达模式在不同动物之间有所不同，并且与拷贝数无关。我们还表明外源DNA序列通过雄性种系传递，并且每个后代都含有整合到基因组不同区域的基因。
