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Warren WC, Rice ES, Maggs X, Roback E, Keene A, Martin F, Ogeh D, Haggerty L, Carroll RA, McGaugh S, Rohner N. Astyanax mexicanus surface and cavefish chromosome-scale assemblies for trait variation discovery. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.16.567450. [PMID: 38014157 PMCID: PMC10680795 DOI: 10.1101/2023.11.16.567450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The ability of organisms to adapt to sudden extreme environmental changes produces some of the most drastic examples of rapid phenotypic evolution. The Mexican Tetra, Astyanax mexicanus, is abundant in the surface waters of northeastern Mexico, but repeated colonizations of cave environments have resulted in the independent evolution of troglomorphic phenotypes in several populations. Here, we present three chromosome-scale assemblies of this species, for one surface and two cave populations, enabling the first whole-genome comparisons between independently evolved cave populations to evaluate the genetic basis for the evolution of adaptation to the cave environment. Our assemblies represent the highest quality of sequence completeness with predicted protein-coding and non-coding gene metrics far surpassing prior resources and, to our knowledge, all long-read assembled teleost genomes, including zebrafish. Whole genome synteny alignments show highly conserved gene order among cave forms in contrast to a higher number of chromosomal rearrangements when compared to other phylogenetically close or distant teleost species. By phylogenetically assessing gene orthology across distant branches of amniotes, we discover gene orthogroups unique to A. mexicanus. When compared to a representative surface fish genome, we find a rich amount of structural sequence diversity, defined here as the number and size of insertions and deletions as well as expanding and contracting repeats across cave forms. These new more complete genomic resources ensure higher trait resolution for comparative, functional, developmental, and genetic studies of drastic trait differences within a species.
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Affiliation(s)
- Wesley C. Warren
- Department of Animal Sciences, Department of Surgery, University of Missouri, Bond Life Sciences Center, Columbia, MO
- Institute for Data Science and Informatics, University of Missouri, Columbia, MO
| | - Edward S. Rice
- Department of Animal Sciences, Department of Surgery, University of Missouri, Bond Life Sciences Center, Columbia, MO
| | - X Maggs
- Department of Animal Sciences, Department of Surgery, University of Missouri, Bond Life Sciences Center, Columbia, MO
| | - Emma Roback
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN
| | - Alex Keene
- Department of Biology, Texas AM University, College Station, TX
| | - Fergal Martin
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Denye Ogeh
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Leanne Haggerty
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Rachel A. Carroll
- Department of Animal Sciences, Department of Surgery, University of Missouri, Bond Life Sciences Center, Columbia, MO
| | - Suzanne McGaugh
- Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, MN
| | - Nicolas Rohner
- Stowers Institute for Medical Research, Kansas City, MO
- Department of Molecular and Integrative Physiology, KU Medical Center, Kansas City, KS
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Frith MC. Paleozoic Protein Fossils Illuminate the Evolution of Vertebrate Genomes and Transposable Elements. Mol Biol Evol 2022; 39:6555113. [PMID: 35348724 PMCID: PMC9004415 DOI: 10.1093/molbev/msac068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Genomes hold a treasure trove of protein fossils: fragments of formerly protein-coding DNA, which mainly come from transposable elements (TEs) or host genes. These fossils reveal ancient evolution of TEs and genomes, and many fossils have been exapted to perform diverse functions important for the host's fitness. However, old and highly-degraded fossils are hard to identify, standard methods (e.g. BLAST) are not optimized for this task, and few Paleozoic protein fossils have been found. Here, a recently optimized method is used to find protein fossils in vertebrate genomes. It finds Paleozoic fossils predating the amphibian/amniote divergence from most major TE categories, including virus-related Polinton and Gypsy elements. It finds 10 fossils in the human genome (8 from TEs and 2 from host genes) that predate the last common ancestor of all jawed vertebrates, probably from the Ordovician period. It also finds types of transposon and retrotransposon not found in human before. These fossils have extreme sequence conservation, indicating exaptation: some have evidence of gene-regulatory function, and they tend to lienearest to developmental genes. Some ancient fossils suggest "genome tectonics", where two fragments of one TE have drifted apart by up to megabases, possibly explaining gene deserts and large introns. This paints a picture of great TE diversity in our aquatic ancestors, with patchy TE inheritance by later vertebrates, producing new genes and regulatory elements on the way. Host-gene fossils too have contributed anciently-conserved DNA segments. This paves the way to further studies of ancient protein fossils.
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Affiliation(s)
- Martin C Frith
- Artificial Intelligence Research Center, AIST, Tokyo, Japan.,Graduate School of Frontier Sciences, University of Tokyo, Chiba, Japan.,Computational Bio Big-Data Open Innovation Laboratory, AIST, Tokyo, Japan
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