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Elife. 2016 Nov 28;5. pii: e19090. doi: 10.7554/eLife.19090.

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

Author information

1
Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, United States.
2
Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, United States.
3
Biochemistry and Molecular Biology, Southern Illinois University, Carbondale, United States.
4
J. Craig Venter Institute, Rockville, United States.
5
Eli and Edythe L. Broad Institute of Harvard and MIT, Cambridge, United States.
6
Institute of Molecular Biotechnology, Vienna, Austria.
7
Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, United States.
8
MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
9
Department of Microbiology and Immunology, Cornell University, Ithaca, United States.
10
Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.

Abstract

The germline genome of the binucleated ciliate Tetrahymena thermophila undergoes programmed chromosome breakage and massive DNA elimination to generate the somatic genome. Here, we present a complete sequence assembly of the germline genome and analyze multiple features of its structure and its relationship to the somatic genome, shedding light on the mechanisms of genome rearrangement as well as the evolutionary history of this remarkable germline/soma differentiation. Our results strengthen the notion that a complex, dynamic, and ongoing interplay between mobile DNA elements and the host genome have shaped Tetrahymena chromosome structure, locally and globally. Non-standard outcomes of rearrangement events, including the generation of short-lived somatic chromosomes and excision of DNA interrupting protein-coding regions, may represent novel forms of developmental gene regulation. We also compare Tetrahymena's germline/soma differentiation to that of other characterized ciliates, illustrating the wide diversity of adaptations that have occurred within this phylum.

KEYWORDS:

Tetrahymena thermophila; centromere; chromosome breakage; chromosomes; evolutionary biology; genes; genome rearrangement; genomics; intermal eliminated sequence; transposable element

PMID:
27892853
PMCID:
PMC5182062
DOI:
10.7554/eLife.19090
[Indexed for MEDLINE]
Free PMC Article

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