He H, Liao C, Edström J E
Department of Genetics, Lund University, Sölvegatan 29, S-22362 Lund, Sweden.
Chromosoma. 1998 Nov;107(5):304-10. doi: 10.1007/s004120050312.
A 155-bp tandem repeat was previously reported to be present in all centromeric regions of the dipteran Chironomus pallidivittatus. We have now isolated a second centromere specific tandem repeat, 375 bp long. Two blocks were found of the new unit, differing in size, probably representing allelic forms. The repeat is present only in chromosome 3, bordering 155-bp repeat arrays. There are about 100 repeats per genome, compared to 1300 units for the 155-bp repeat. The two units contain an identical 9-bp sequence which can form target-site duplications flanking a short mobile element, Cp1. An inversion within the tandem array was isolated, the breakpoint of which is within the 9-bp target sequence. Another short shared motif, 10-bp long, is also present at the insertion site for a mobile element. The two repeat units are similar in having long regions with more than 80% AT and an overall high AT content.
先前有报道称，在双翅目昆虫苍白摇蚊的所有着丝粒区域都存在一个155碱基对的串联重复序列。我们现在分离出了第二个着丝粒特异性串联重复序列，长度为375碱基对。发现了两个新单元块，大小不同，可能代表等位基因形式。该重复序列仅存在于3号染色体上，与155碱基对的重复序列阵列相邻。每个基因组约有100个重复序列，而155碱基对的重复序列有1300个单元。这两个单元包含一个相同的9碱基对序列，该序列可在一个短移动元件Cp1两侧形成靶位点重复。在串联阵列中分离出一个倒位，其断点位于9碱基对的靶序列内。在一个移动元件的插入位点也存在另一个10碱基对长的短共享基序。这两个重复单元的相似之处在于，它们都有长区域，其中AT含量超过80%，且总体AT含量较高。
