McClements W, Skalka A M
Science. 1977 Apr 8;196(4286):195-7. doi: 10.1126/science.557836.
The ribosomal RNA genes (ribosomal DNA) of chicken are present in approximately 200 copies and are cleaved into two fragments of molecular weight 5 X 10(6) and 12 to 14 X 10(6) by restriction endonuclease Eco RI. Recombinant phages have been constructed in vitro by joining the smaller fragment of ribosomal DNA and the outer arms of DNA from the vector lambdagtWES-lambdaC. In one of the recombinants, the coding strand of the cloned fragment is in the proper orientation for transcription with lambda "early" genes; in the other two the orientation is reversed, with the coding strand in the proper position for transcription with lambda "late" genes.
鸡的核糖体RNA基因（核糖体DNA）约有200个拷贝，用限制性内切酶Eco RI可将其切割成分子量分别为5×10⁶和12至14×10⁶的两个片段。通过将核糖体DNA的较小片段与载体λgtWES-λC的DNA外臂连接，已在体外构建了重组噬菌体。在其中一个重组体中，克隆片段的编码链与λ“早期”基因转录的方向相同；在另外两个重组体中，方向相反，编码链处于与λ“晚期”基因转录的正确位置。
