Nongenic, bidirectional transcription precedes and may promote developmental DNA deletion in Tetrahymena thermophila

Douglas L. Chalker, Meng Chao Yao

Research output: Contribution to journalArticlepeer-review

136 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)1287-1298
Number of pages12
JournalGenes and Development
Volume15
Issue number10
DOIs
StatePublished - May 15 2001

Keywords

  • Ciliates
  • DNA rearrangement
  • Intergenic transcription
  • Nuclear development

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