Evolutionary Conservation of Sequences Directing Chromosome Breakage and RDNA Palindrome Formation in Tetrahymenine Ciliates

Overview

Journal Genetics

Publisher Oxford University Press

Specialty Genetics

Date 1996 Dec 1

PMID 8978037

Citations 15

Authors

R S Coyne

M C Yao

Affiliations

Soon will be listed here.

Abstract

Extensive, programmed chromosome breakage occurs during formation of the somatic macronucleus of ciliated protozoa. The cis-acting signal directing breakage has been most rigorously defined in Tetrahymena thermophila, where it consists of a 15-bp DNA sequence known as Cbs, for chromosome breakage sequence. We have identified sequences identical or nearly identical to the T. thermophila Cbs at sites of breakage flanking the germline micronuclear rDNA locus of six additional species of Tetrahymena as well as members of two related genera. Other general features of the breakage site are also conserved, but surprisingly, the orientation and number of copies of Cbs are not always conserved, suggesting the occurrence of germline rearrangement events over evolutionary time. At one end of the T. thermophila micronuclear rDNA locus, a pair of short inverted repeats adjacent to Cbs directs the formation of a giant palindromic molecule. We have examined the corresponding sequences from two other Tetrahymena species. We find the sequence to be partially conserved, as previously implied from analysis of macronuclear rDNA, but of variable length and organization.

Citing Articles

Programmed chromosome fragmentation in ciliated protozoa: multiple means to chromosome ends.

Betermier M, Klobutcher L, Orias E Microbiol Mol Biol Rev. 2023; 87(4):e0018422.

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Evolutionary rates of mammalian telomere-stability genes correlate with karyotype features and female germline expression.

Pontremoli C, Forni D, Cagliani R, Pozzoli U, Clerici M, Sironi M Nucleic Acids Res. 2018; 46(14):7153-7168.

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A germline-limited piggyBac transposase gene is required for precise excision in Tetrahymena genome rearrangement.

Feng L, Wang G, Hamilton E, Xiong J, Yan G, Chen K Nucleic Acids Res. 2017; 45(16):9481-9502.

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Structure of the germline genome of and relationship to the massively rearranged somatic genome.

Hamilton E, Kapusta A, Huvos P, Bidwell S, Zafar N, Tang H Elife. 2016; 5.

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Programmed Minichromosome Elimination as a Mechanism for Somatic Genome Reduction in Tetrahymena thermophila.

Lin C, Lin I, Yao M PLoS Genet. 2016; 12(11):e1006403.

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