Rae P M
Nucleic Acids Res. 1981 Oct 10;9(19):4997-5010. doi: 10.1093/nar/9.19.4997.
The nucleotide sequences at and around the termini of 5 kb type 1 interruptions in three separate clones of D. melanogaster rDNA repeats have been determined, and have been compared with the sequence of the corresponding region of an insertion-free rDNA repeat. All three interrupted rDNA repeats contain a small deletion of 28S rRNA coding material at the left coding/insertion sequence junction. A second deletion was found in one of the three clones, ad other aberrations were suggested by the results of restriction enzyme digestions of unfractionated rDNA. The termini of 5 kb type 1 rDNA insertions in D. melanogaster were also compared with the corresponding regions of 28S rDNA interruptions in D. virilis: the insertion site is identical in the two species, but the termini of the two species' interruptions show no homology. I sequenced a 1.1 kb region of the 5 kb type 1 D. melanogaster rDNA interruption that covers the sequences of the 1 kb and 0.5 kb insertions. There is 98% homology between the rightmost 1 kb of the 5 kb interruption and the sequences of the shorter insertions. Data suggest that Drosophila rDNA interruptions arose as a transposable element, and that divergence had included length alterations generated by unequal crossing over.
已确定黑腹果蝇rDNA重复序列的三个独立克隆中5kb 1型中断末端及其周围的核苷酸序列，并将其与无插入rDNA重复序列相应区域的序列进行了比较。所有三个中断的rDNA重复序列在左编码/插入序列连接处都有一段28S rRNA编码材料的小缺失。在三个克隆中的一个中发现了第二个缺失，未分级rDNA的限制性酶切结果也提示了其他畸变。还将黑腹果蝇中5kb 1型rDNA插入的末端与粗壮果蝇中28S rDNA中断的相应区域进行了比较：两个物种的插入位点相同，但两个物种中断的末端没有同源性。我对黑腹果蝇5kb 1型rDNA中断的一个1.1kb区域进行了测序，该区域涵盖了1kb和0.5kb插入片段的序列。5kb中断最右侧1kb与较短插入片段的序列之间有98%的同源性。数据表明，果蝇rDNA中断是作为一种转座元件出现的，并且分歧包括由不等交换产生的长度改变。
