Telomere-specific non-LTR retrotransposons and telomere maintenance in the silkworm, Bombyx mori
Telomere-specific non-LTR retrotransposons and telomere maintenance in the silkworm, Bombyx mori
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DOI：
10.1007/s10577-005-0990-9
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发表时间：
2005-07-01
影响因子：
2.6
通讯作者：
Kojima, KK
中科院分区：
文献类型：
--
作者：
Fujiwara, H;Osanai, M;Kojima, KK
大多数昆虫具有由端粒酶合成的五核苷酸（TTAGG）端粒重复序列组成的端粒。然而，所有的双翅目物种，到目前为止，研究和其他几个物种的昆虫失去了（TTAGG）（n）重复，这表明他们中的一些招募端粒非依赖性端粒维持。家蚕保留了染色体末端的TTAGG基序，但在各种组织的各个阶段都表达相当低水平的端粒酶活性。就在B中TTAGG重复序列的6-8-kb片段附近。在mori中，超过1000个拷贝的非LTR反转录转座子，称为TRAS和SART家族，出现在端粒重复序列中并积累。TRAS和SART大量转录并以高度序列特异性的方式主动反转录转座成TTAGG端粒重复序列。它们有三种可能的机制来确保特异性整合到端粒重复序列中。本文着重介绍了B中端粒结构和端粒特异性非LTR反转录转座子。并讨论了这种昆虫端粒维持的机制。
Most insects have telomeres that consist of pentanucleotide (TTAGG) telomeric repeats, which are synthesized by telomerase. However, all species in Diptera so far examined and several species in other orders of insect have lost the (TTAGG)(n) repeats, suggesting that some of them recruit telomerase-independent telomere maintenance. The silkworm, Bombyx mori, retains the TTAGG motifs in the chromosomal ends but expresses quite a low level of telomerase activity in all stages of various tissues. Just proximal to a 6-8-kb stretch of the TTAGG repeats in B. mori, more than 1000 copies of non-LTR retrotransposons, designated TRAS and SART families, occur among the telomeric repeats and accumulate. TRAS and SART are abundantly transcribed and actively retrotransposed into TTAGG telomeric repeats in a highly sequence-specific manner. They have three possible mechanisms to ensure specific integration into the telomeric repeats. This article focuses on the telomere structure and telomere-specific non-LTR retrotransposons in B. mori and discusses the mechanisms for telomere maintenance in this insect.