African lungfish genome sheds light on the vertebrate water-to-land transition
- PMID: 33545087
- DOI: 10.1016/j.cell.2021.01.047
African lungfish genome sheds light on the vertebrate water-to-land transition
Abstract
Lungfishes are the closest extant relatives of tetrapods and preserve ancestral traits linked with the water-to-land transition. However, their huge genome sizes have hindered understanding of this key transition in evolution. Here, we report a 40-Gb chromosome-level assembly of the African lungfish (Protopterus annectens) genome, which is the largest genome assembly ever reported and has a contig and chromosome N50 of 1.60 Mb and 2.81 Gb, respectively. The large size of the lungfish genome is due mainly to retrotransposons. Genes with ultra-long length show similar expression levels to other genes, indicating that lungfishes have evolved high transcription efficacy to keep gene expression balanced. Together with transcriptome and experimental data, we identified potential genes and regulatory elements related to such terrestrial adaptation traits as pulmonary surfactant, anxiolytic ability, pentadactyl limbs, and pharyngeal remodeling. Our results provide insights and key resources for understanding the evolutionary pathway leading from fishes to humans.
Keywords: aestivation; ancestral karyotype; anxiolytic ability; huge genome size; lungfishes; pentadactyl limbs; pharyngeal remodeling; pulmonary surfactant; water-to-land transition.
Copyright © 2021 Elsevier Inc. All rights reserved.
Conflict of interest statement
Declaration of interests The authors declare no competing interests.
Comment in
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Giant genomes of lungfish.Nat Rev Genet. 2021 Apr;22(4):199. doi: 10.1038/s41576-021-00337-9. Nat Rev Genet. 2021. PMID: 33597743 No abstract available.
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Evolution: The deep genetic roots of tetrapod-specific traits.Curr Biol. 2021 May 24;31(10):R467-R469. doi: 10.1016/j.cub.2021.03.096. Curr Biol. 2021. PMID: 34033765
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