THE INTERNALLY LOCATED TELOMERIC SEQUENCES IN THE GERM-LINE CHROMOSOMES OF TETRAHYMENA ARE AT THE ENDS OF TRANSPOSON-LIKE ELEMENTS
THE INTERNALLY LOCATED TELOMERIC SEQUENCES IN THE GERM-LINE CHROMOSOMES OF TETRAHYMENA ARE AT THE ENDS OF TRANSPOSON-LIKE ELEMENTS
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DOI：
10.1016/0092-8674(85)90248-x
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发表时间：
1985-12-01
期刊：
影响因子：
64.5
通讯作者：
BLACKBURN, EH
中科院分区：
文献类型：
--
作者：
CHERRY, JM;BLACKBURN, EH
纤毛虫嗜热四膜虫种系微核基因组含有.apprx。串联重复C4A2序列的102个染色体内部块（mic C4A2）。这个重复序列就是体细胞巨核的端粒序列。6个micC4A2克隆序列中，每一个都与一个保守的30 bp序列相邻，我们认为这是一个DNA元件家族（Tel-1家族）的末端反向重复序列。这个30 bp的序列包含一个不常切割的限制性内切酶Bst XI的位点，该酶允许从微核基因组中剪切全长的Tel-1元件。BST xi切割的微核DNA的BAL 31酶切结果显示，大部分mic4a2片段与Tel-1家族的末端相关。我们提出Tel-1元件是可转座的，并提出了一种新的机制来解释micC4A2的起源，其中端粒重复序列在重新整合之前被添加到可转座元件的自由线性形式的末端。
The germ-line micronuclear genome of the ciliate Tetrahymena thermophila contains .apprx. 102 chromosome-internal blocks of tandemly repeated C4A2 sequences (mic C4A2). This repeated sequence is the telomeric sequence in the somatic macronucleus. Each of six cloned micC4A2 was found to be adjacent to a conserved 30 bp sequence, which we propose is the terminal inverted repeat of a family of DNA elements (the Tel-1 family). This 30 bp sequence contains a site for the infrequently cutting restriction enzyme Bst XI, which allows full-length Tel-1 elements to be cut out of the micronuclear genome. BAL 31 exonuclease digestion of BST XI-cut micronuclear DNA showed the majority of mic C4A2 blocks to be associated with the ends of the Tel-1 family. We propose that Tel-1 elements are transposable and suggest a novel mechanism to account for the origin of micC4A2, in which telomeric repeats are added to the ends of free linear forms of the transposable elements prior to reintegration.