Krolewski J J, Rush M G
J Mol Biol. 1984 Mar 25;174(1):31-40. doi: 10.1016/0022-2836(84)90363-2.
A 300 base-pair (bp) size class of small polydisperse circular DNA (spcDNA) isolated from the BSC-1 line of African Green monkey kidney cells was cleaved with the restriction endonuclease Sau3A, and the resulting fragments (100 to 200 bp) were cloned in bacteriophage M13 mp7. The nucleotide sequence of each of 24 clones containing DNA sequences homologous to the Alu family of mobile, dispersed, repetitive elements was then determined. Analysis of these sequences revealed that many, and perhaps all, of the 300 bp Alu-containing spcDNAs had regions in which the 5' and 3' ends of the normal Alu element were juxtaposed and covalently joined. Although more than one model can explain the generation of such circular molecules, the most attractive one at this time involves their generation from reverse transcripts of Alu-specific RNAs.
从非洲绿猴肾细胞的BSC-1系中分离出的一类300个碱基对（bp）大小的小多分散环状DNA（spcDNA），用限制性内切酶Sau3A进行切割，得到的片段（100至200bp）克隆到噬菌体M13 mp7中。然后测定了24个含有与Alu家族可移动、分散、重复元件的DNA序列同源的克隆的核苷酸序列。对这些序列的分析表明，许多（也许是所有）含有300bp Alu的spcDNA都有正常Alu元件的5'和3'末端并列并共价连接的区域。虽然不止一种模型可以解释这种环状分子的产生，但目前最有吸引力的模型是它们由Alu特异性RNA的逆转录产物产生。
