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Nat Ecol Evol. 2019 Mar;3(3):469-478. doi: 10.1038/s41559-019-0812-7. Epub 2019 Feb 25.

Antarctic blackfin icefish genome reveals adaptations to extreme environments.

Author information

1
Unit of Polar Genomics, Korea Polar Research Institute, Incheon, Korea.
2
Institute of Neuroscience, University of Oregon, Eugene, OR, USA.
3
Department of Polar Life Science, Korea Polar Research Institute, Incheon, Korea.
4
Polar Science, University of Science and Technology, Daejeon, Korea.
5
Department of Animal Biology, University of Illinois, Champaign, IL, USA.
6
McDonnell Genome Institute, Washington University, St. Louis, MO, USA.
7
Department of Developmental Biochemistry, Biocenter, University of Wuerzburg, Wuerzburg, Germany. phch1@biozentrum.uni-wuerzburg.de.
8
Hagler Institute for Advanced Study, Texas A&M University, College Station, TX, USA. phch1@biozentrum.uni-wuerzburg.de.
9
Department of Biology, Texas A&M University, College Station, TX, USA. phch1@biozentrum.uni-wuerzburg.de.
10
Department of Marine and Environmental Sciences, Northeastern University Marine Science Center, Nahant, MA, USA. w.detrich@northeastern.edu.
11
Institute of Neuroscience, University of Oregon, Eugene, OR, USA. jpostle@uoneuro.uoregon.edu.
12
Unit of Polar Genomics, Korea Polar Research Institute, Incheon, Korea. hpark@kopri.re.kr.
13
Polar Science, University of Science and Technology, Daejeon, Korea. hpark@kopri.re.kr.

Abstract

Icefishes (suborder Notothenioidei; family Channichthyidae) are the only vertebrates that lack functional haemoglobin genes and red blood cells. Here, we report a high-quality genome assembly and linkage map for the Antarctic blackfin icefish Chaenocephalus aceratus, highlighting evolved genomic features for its unique physiology. Phylogenomic analysis revealed that Antarctic fish of the teleost suborder Notothenioidei, including icefishes, diverged from the stickleback lineage about 77 million years ago and subsequently evolved cold-adapted phenotypes as the Southern Ocean cooled to sub-zero temperatures. Our results show that genes involved in protection from ice damage, including genes encoding antifreeze glycoprotein and zona pellucida proteins, are highly expanded in the icefish genome. Furthermore, genes that encode enzymes that help to control cellular redox state, including members of the sod3 and nqo1 gene families, are expanded, probably as evolutionary adaptations to the relatively high concentration of oxygen dissolved in cold Antarctic waters. In contrast, some crucial regulators of circadian homeostasis (cry and per genes) are absent from the icefish genome, suggesting compromised control of biological rhythms in the polar light environment. The availability of the icefish genome sequence will accelerate our understanding of adaptation to extreme Antarctic environments.

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PMID:
30804520
DOI:
10.1038/s41559-019-0812-7
[Indexed for MEDLINE]

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