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Benham PM, Cicero C, Escalona M, Beraut E, Fairbairn C, Marimuthu MPA, Nguyen O, Sahasrabudhe R, King BL, Thomas WK, Kovach AI, Nachman MW, Bowie RCK. Remarkably High Repeat Content in the Genomes of Sparrows: The Importance of Genome Assembly Completeness for Transposable Element Discovery. Genome Biol Evol 2024; 16:evae067. [PMID: 38566597 PMCID: PMC11088854 DOI: 10.1093/gbe/evae067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 03/01/2024] [Accepted: 03/23/2024] [Indexed: 04/04/2024] Open
Abstract
Transposable elements (TE) play critical roles in shaping genome evolution. Highly repetitive TE sequences are also a major source of assembly gaps making it difficult to fully understand the impact of these elements on host genomes. The increased capacity of long-read sequencing technologies to span highly repetitive regions promises to provide new insights into patterns of TE activity across diverse taxa. Here we report the generation of highly contiguous reference genomes using PacBio long-read and Omni-C technologies for three species of Passerellidae sparrow. We compared these assemblies to three chromosome-level sparrow assemblies and nine other sparrow assemblies generated using a variety of short- and long-read technologies. All long-read based assemblies were longer (range: 1.12 to 1.41 Gb) than short-read assemblies (0.91 to 1.08 Gb) and assembly length was strongly correlated with the amount of repeat content. Repeat content for Bell's sparrow (31.2% of genome) was the highest level ever reported within the order Passeriformes, which comprises over half of avian diversity. The highest levels of repeat content (79.2% to 93.7%) were found on the W chromosome relative to other regions of the genome. Finally, we show that proliferation of different TE classes varied even among species with similar levels of repeat content. These patterns support a dynamic model of TE expansion and contraction even in a clade where TEs were once thought to be fairly depauperate and static. Our work highlights how the resolution of difficult-to-assemble regions of the genome with new sequencing technologies promises to transform our understanding of avian genome evolution.
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Affiliation(s)
- Phred M Benham
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Carla Cicero
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Merly Escalona
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, CA 95064, USA
| | - Eric Beraut
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Colin Fairbairn
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Mohan P A Marimuthu
- DNA Technologies and Expression Analysis Core Laboratory, Genome Center, University of California-Davis, Davis, CA 95616, USA
| | - Oanh Nguyen
- DNA Technologies and Expression Analysis Core Laboratory, Genome Center, University of California-Davis, Davis, CA 95616, USA
| | - Ruta Sahasrabudhe
- DNA Technologies and Expression Analysis Core Laboratory, Genome Center, University of California-Davis, Davis, CA 95616, USA
| | - Benjamin L King
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME 04469, USA
| | - W Kelley Thomas
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Adrienne I Kovach
- Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH 03824, USA
| | - Michael W Nachman
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Rauri C K Bowie
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA 94720, USA
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
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Bours A, Pruisscher P, Bascón-Cardozo K, Odenthal-Hesse L, Liedvogel M. The blackcap (Sylvia atricapilla) genome reveals a recent accumulation of LTR retrotransposons. Sci Rep 2023; 13:16471. [PMID: 37777595 PMCID: PMC10542752 DOI: 10.1038/s41598-023-43090-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 09/19/2023] [Indexed: 10/02/2023] Open
Abstract
Transposable elements (TEs) are mobile genetic elements that can move around the genome, and as such are a source of genomic variability. Based on their characteristics we can annotate TEs within the host genome and classify them into specific TE types and families. The increasing number of available high-quality genome references in recent years provides an excellent resource that will enhance the understanding of the role of recently active TEs on genetic variation and phenotypic evolution. Here we showcase the use of a high-quality TE annotation to understand the distinct effect of recent and ancient TE insertions on the evolution of genomic variation, within our study species the Eurasian blackcap (Sylvia atricapilla). We investigate how these distinct TE categories are distributed along the genome and evaluate how their coverage across the genome is correlated with four genomic features: recombination rate, gene coverage, CpG island coverage and GC content. We found within the recent TE insertions an accumulation of LTRs previously not seen in birds. While the coverage of recent TE insertions was negatively correlated with both GC content and recombination rate, the correlation with recombination rate disappeared and turned positive for GC content when considering ancient TE insertions.
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Affiliation(s)
- Andrea Bours
- MPRG Behavioural Genomics, Max Planck Institute for Evolutionary Biology, 24306, Plön, Germany.
| | - Peter Pruisscher
- MPRG Behavioural Genomics, Max Planck Institute for Evolutionary Biology, 24306, Plön, Germany
- Department of Evolutionary Biology, Evolutionary Biology Centre (EBC), Uppsala University, Uppsala, Sweden
| | - Karen Bascón-Cardozo
- MPRG Behavioural Genomics, Max Planck Institute for Evolutionary Biology, 24306, Plön, Germany
| | - Linda Odenthal-Hesse
- Department Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, 24306, Plön, Germany
| | - Miriam Liedvogel
- MPRG Behavioural Genomics, Max Planck Institute for Evolutionary Biology, 24306, Plön, Germany.
- Institute of Avian Research "Vogelwarte Helgoland", 26386, Wilhelmshaven, Germany.
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Catalán A, Merondun J, Knief U, Wolf JBW. Chromatin accessibility, not 5mC methylation covaries with partial dosage compensation in crows. PLoS Genet 2023; 19:e1010901. [PMID: 37747941 PMCID: PMC10575545 DOI: 10.1371/journal.pgen.1010901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 10/13/2023] [Accepted: 08/07/2023] [Indexed: 09/27/2023] Open
Abstract
The evolution of genetic sex determination is often accompanied by degradation of the sex-limited chromosome. Male heterogametic systems have evolved convergent, epigenetic mechanisms restoring the resulting imbalance in gene dosage between diploid autosomes (AA) and the hemizygous sex chromosome (X). Female heterogametic systems (AAf Zf, AAm ZZm) tend to only show partial dosage compensation (0.5 < Zf:AAf < 1) and dosage balance (0.5
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Affiliation(s)
- Ana Catalán
- Department of Evolutionary Biology, Evolutionary Biology Centre (EBC), Uppsala University, Uppsala, Sweden
- Division of Evolutionary Biology, LMU Munich, Planegg-Martinsried, Germany
| | - Justin Merondun
- Division of Evolutionary Biology, LMU Munich, Planegg-Martinsried, Germany
| | - Ulrich Knief
- Division of Evolutionary Biology, LMU Munich, Planegg-Martinsried, Germany
- Evolutionary Biology & Ecology,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Jochen B. W. Wolf
- Department of Evolutionary Biology, Evolutionary Biology Centre (EBC), Uppsala University, Uppsala, Sweden
- Division of Evolutionary Biology, LMU Munich, Planegg-Martinsried, Germany
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Benham PM, Cicero C, DeRaad DA, McCormack JE, Wayne RK, Escalona M, Beraut E, Marimuthu MPA, Nguyen O, Nachman MW, Bowie RCK. A highly contiguous reference genome for the Steller's jay (Cyanocitta stelleri). J Hered 2023; 114:549-560. [PMID: 37395718 PMCID: PMC10445514 DOI: 10.1093/jhered/esad042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 06/29/2023] [Indexed: 07/04/2023] Open
Abstract
The Steller's jay is a familiar bird of western forests from Alaska south to Nicaragua. Here, we report a draft reference assembly for the species generated from PacBio HiFi long-read and Omni-C chromatin-proximity sequencing data as part of the California Conservation Genomics Project (CCGP). Sequenced reads were assembled into 352 scaffolds totaling 1.16 Gb in length. Assembly metrics indicate a highly contiguous and complete assembly with a contig N50 of 7.8 Mb, scaffold N50 of 25.8 Mb, and BUSCO completeness score of 97.2%. Repetitive elements span 16.6% of the genome including nearly 90% of the W chromosome. Compared with high-quality assemblies from other members of the family Corvidae, the Steller's jay genome contains a larger proportion of repetitive elements than 4 crow species (Corvus), but a lower proportion of repetitive elements than the California scrub-jay (Aphelocoma californica). This reference genome will serve as an essential resource for future studies on speciation, local adaptation, phylogeography, and conservation genetics in this species of significant biological interest.
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Affiliation(s)
- Phred M Benham
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, United States
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, United States
| | - Carla Cicero
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, United States
| | - Devon A DeRaad
- Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, United States
| | - John E McCormack
- Moore Laboratory of Zoology, Occidental College, Los Angeles, CA, United States
| | - Robert K Wayne
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Merly Escalona
- Department of Biomolecular Engineering, University of California Santa Cruz, Santa Cruz, CA, United States
| | - Eric Beraut
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Mohan P A Marimuthu
- DNA Technologies and Expression Analysis Core Laboratory, Genome Center, University of California-Davis, Davis, CA, United States
| | - Oanh Nguyen
- DNA Technologies and Expression Analysis Core Laboratory, Genome Center, University of California-Davis, Davis, CA, United States
| | - Michael W Nachman
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, United States
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, United States
| | - Rauri C K Bowie
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, United States
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, United States
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Wang J, Yuan L, Tang J, Liu J, Sun C, Itgen MW, Chen G, Sessions SK, Zhang G, Mueller RL. Transposable element and host silencing activity in gigantic genomes. Front Cell Dev Biol 2023; 11:1124374. [PMID: 36910142 PMCID: PMC9998948 DOI: 10.3389/fcell.2023.1124374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 02/09/2023] [Indexed: 02/26/2023] Open
Abstract
Transposable elements (TEs) and the silencing machinery of their hosts are engaged in a germline arms-race dynamic that shapes TE accumulation and, therefore, genome size. In animal species with extremely large genomes (>10 Gb), TE accumulation has been pushed to the extreme, prompting the question of whether TE silencing also deviates from typical conditions. To address this question, we characterize TE silencing via two pathways-the piRNA pathway and KRAB-ZFP transcriptional repression-in the male and female gonads of Ranodon sibiricus, a salamander species with a ∼21 Gb genome. We quantify 1) genomic TE diversity, 2) TE expression, and 3) small RNA expression and find a significant relationship between the expression of piRNAs and TEs they target for silencing in both ovaries and testes. We also quantified TE silencing pathway gene expression in R. sibiricus and 14 other vertebrates with genome sizes ranging from 1 to 130 Gb and find no association between pathway expression and genome size. Taken together, our results reveal that the gigantic R. sibiricus genome includes at least 19 putatively active TE superfamilies, all of which are targeted by the piRNA pathway in proportion to their expression levels, suggesting comprehensive piRNA-mediated silencing. Testes have higher TE expression than ovaries, suggesting that they may contribute more to the species' high genomic TE load. We posit that apparently conflicting interpretations of TE silencing and genomic gigantism in the literature, as well as the absence of a correlation between TE silencing pathway gene expression and genome size, can be reconciled by considering whether the TE community or the host is currently "on the attack" in the arms race dynamic.
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Affiliation(s)
- Jie Wang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China
| | - Liang Yuan
- School of Life Sciences, Xinjiang Normal University, Urumqi, China
| | - Jiaxing Tang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China.,College of Life Sciences, Sichuan Normal University, Chengdu, China
| | - Jiongyu Liu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China
| | - Cheng Sun
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Michael W Itgen
- Department of Biology, Colorado State University, Fort Collins, CO, United States
| | - Guiying Chen
- College of Life Sciences, Sichuan Normal University, Chengdu, China
| | | | - Guangpu Zhang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan, China.,College of Life Sciences, Sichuan Normal University, Chengdu, China
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