Adey N B, Tollefsbol T O, Sparks A B, Edgell M H, Hutchison C A
Department of Microbiology and Immunology, University of North Carolina at Chapel Hill 27599.
Proc Natl Acad Sci U S A. 1994 Feb 15;91(4):1569-73. doi: 10.1073/pnas.91.4.1569.
The F-type subfamily of LINE-1 or L1 retroposons [for long interspersed (repetitive) element 1] was dispersed in the mouse genome several million years ago. This subfamily appears to be both transcriptionally and transpositionally inactive today and therefore may be considered evolutionarily extinct. We hypothesized that these F-type L1s are inactive because of the accumulation of mutations. To test this idea we used phylogenetic analysis to deduce the sequence of a transpositionally active ancestral F-type promoter, resurrected it by chemical synthesis, and showed that it has promoter activity. In contrast, F-type sequences isolated from the modern genome are inactive. This approach, in which the automated DNA synthesizer is used as a "time machine," should have broad application in testing models derived from evolutionary studies.
LINE-1或L1反转录转座子（长散在（重复）元件1）的F型亚家族在几百万年前就散布于小鼠基因组中。如今这个亚家族在转录和转座方面似乎都不活跃，因此可以认为在进化上已灭绝。我们推测这些F型L1不活跃是由于突变的积累。为了验证这一想法，我们通过系统发育分析推断出一个具有转座活性的祖先F型启动子的序列，通过化学合成使其复活，并证明它具有启动子活性。相比之下，从现代基因组中分离出的F型序列是不活跃的。这种将自动化DNA合成仪用作“时间机器”的方法，在测试源自进化研究的模型方面应具有广泛的应用。
