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Developmental regulation of DNA replication: replication fork barriers and programmed gene amplification in Tetrahymena thermophila.

Publication ,  Journal Article
Zhang, Z; Macalpine, DM; Kapler, GM
Published in: Mol Cell Biol
October 1997

The palindromic Tetrahymena ribosomal DNA (rDNA) minichromosome is amplified 10,000-fold during development. Subsequent vegetative replication is cell cycle regulated. rDNA replication differs fundamentally in cycling vegetative and nondividing amplifying cells. Using two-dimensional gel electrophoresis, we show for the first time that replication origins that direct gene amplification also function in normal dividing cells. Two classes of amplification intermediates were identified. The first class is indistinguishable from vegetative rDNA, initiating in just one of the two 5' nontranscribed spacer (NTS) copies in the rDNA palindrome at either of two closely spaced origins. Thus, these origins are active throughout the life cycle and their regulation changes at different developmental stages. The second, novel class of amplification intermediates is generated by multiple initiation events. Intermediates with mass greater than fully replicated DNA were observed, suggesting that onionskin replication occurs at this stage. Unlike amplified rDNA in Xenopus laevis, the novel Tetrahymena species are not produced by random initiation; replication also initiates in the 5' NTS. Surprisingly, a replication fork barrier which is activated only in these amplifying molecules blocks the progression of forks near the center of the palindrome. Whereas barriers have been previously described, this is the first instance in which programmed regulation of replication fork progression has been demonstrated in a eukaryote.

Duke Scholars

Published In

Mol Cell Biol

DOI

ISSN

0270-7306

Publication Date

October 1997

Volume

17

Issue

10

Start / End Page

6147 / 6156

Location

United States

Related Subject Headings

  • Tetrahymena thermophila
  • Replication Origin
  • Promoter Regions, Genetic
  • Gene Amplification
  • Developmental Biology
  • DNA, Ribosomal
  • DNA, Protozoan
  • DNA Replication
  • Animals
  • 42 Health sciences
 

Citation

APA
Chicago
ICMJE
MLA
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Zhang, Z., Macalpine, D. M., & Kapler, G. M. (1997). Developmental regulation of DNA replication: replication fork barriers and programmed gene amplification in Tetrahymena thermophila. Mol Cell Biol, 17(10), 6147–6156. https://doi.org/10.1128/MCB.17.10.6147
Zhang, Z., D. M. Macalpine, and G. M. Kapler. “Developmental regulation of DNA replication: replication fork barriers and programmed gene amplification in Tetrahymena thermophila.Mol Cell Biol 17, no. 10 (October 1997): 6147–56. https://doi.org/10.1128/MCB.17.10.6147.
Zhang, Z., et al. “Developmental regulation of DNA replication: replication fork barriers and programmed gene amplification in Tetrahymena thermophila.Mol Cell Biol, vol. 17, no. 10, Oct. 1997, pp. 6147–56. Pubmed, doi:10.1128/MCB.17.10.6147.

Published In

Mol Cell Biol

DOI

ISSN

0270-7306

Publication Date

October 1997

Volume

17

Issue

10

Start / End Page

6147 / 6156

Location

United States

Related Subject Headings

  • Tetrahymena thermophila
  • Replication Origin
  • Promoter Regions, Genetic
  • Gene Amplification
  • Developmental Biology
  • DNA, Ribosomal
  • DNA, Protozoan
  • DNA Replication
  • Animals
  • 42 Health sciences