Nongenic, bidirectional transcription precedes and may promote developmental DNA deletion in Tetrahymena thermophila
Nongenic, bidirectional transcription precedes and may promote developmental DNA deletion in Tetrahymena thermophila
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DOI：
10.1101/gad.884601
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发表时间：
2001-05-15
影响因子：
10.5
通讯作者：
Yao, MC
中科院分区：
文献类型：
--
作者：
Chalker, DL;Yao, MC
嗜热四膜虫在发育过程中体细胞核的染色体上切下大量的DNA片段。这些生殖系限制性序列是如何被识别和切除的仍然知之甚少。我们已经发现，许多这些非编码DNA在核发育过程中被转录。生殖系限制性M元件的转录发生在两条DNA链上，并导致1 kb的异质转录物< 200 b to >。当发育中的微核和大核开始分化时，转录本最丰富。转录通常仅限于微核和/或发育核的未重排DNA，但当将生殖系限制的DNA置于体细胞大核中时，可以诱导其自身的转录。对接合细胞进行短暂的放线菌素D处理可以阻止M元件切除，这提供了转录对于有效的DNA重排很重要的证据。我们建议转录靶向这些生殖系限制的序列消除通过改变染色质，以确保其可访问性的切除机制。
A large number of DNA segments are excised from the chromosomes of the somatic nucleus during development of Tetrahymena thermophila. How these germline-limited sequences are recognized and excised is still poorly understood. We have found that many of these noncoding DNAs are transcribed during nuclear development. Transcription of the germline-limited M element occurs from both DNA strands and results in heterogeneous transcripts of < 200 b to > 1 kb. Transcripts are most abundant when developing micro- and macronuclei begin their differentiation. Transcription is normally restricted to unrearranged DNA of micronuclei and/or developing nuclei, but germline-limited DNAs can induce their own transcription when placed into somatic macronuclei. Brief actinomycin D treatment of conjugating cells blocked M-element excision, providing evidence that transcription is important for efficient DNA rearrangement. We propose that transcription targets these germline-limited sequences for elimination by altering chromatin to ensure their accessibility to the excision machinery.