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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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Gable SM, Bushroe N, Mendez J, Wilson A, Pinto B, Gamble T, Tollis M. Differential Conservation and Loss of CR1 Retrotransposons in Squamates Reveals Lineage-Specific Genome Dynamics across Reptiles. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.09.579686. [PMID: 38405926 PMCID: PMC10888918 DOI: 10.1101/2024.02.09.579686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Transposable elements (TEs) are repetitive DNA sequences which create mutations and generate genetic diversity across the tree of life. In amniotic vertebrates, TEs have been mainly studied in mammals and birds, whose genomes generally display low TE diversity. Squamates (Order Squamata; ~11,000 extant species of lizards and snakes) show as much variation in TE abundance and activity as they do in species and phenotypes. Despite this high TE activity, squamate genomes are remarkably uniform in size. We hypothesize that novel, lineage-specific dynamics have evolved over the course of squamate evolution to constrain genome size across the order. Thus, squamates may represent a prime model for investigations into TE diversity and evolution. To understand the interplay between TEs and host genomes, we analyzed the evolutionary history of the CR1 retrotransposon, a TE family found in most tetrapod genomes. We compared 113 squamate genomes to the genomes of turtles, crocodilians, and birds, and used ancestral state reconstruction to identify shifts in the rate of CR1 copy number evolution across reptiles. We analyzed the repeat landscapes of CR1 in squamate genomes and determined that shifts in the rate of CR1 copy number evolution are associated with lineage-specific variation in CR1 activity. We then used phylogenetic reconstruction of CR1 subfamilies across amniotes to reveal both recent and ancient CR1 subclades across the squamate tree of life. The patterns of CR1 evolution in squamates contrast other amniotes, suggesting key differences in how TEs interact with different host genomes and at different points across evolutionary history.
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Affiliation(s)
- Simone M Gable
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, USA
| | - Nicholas Bushroe
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, USA
| | - Jasmine Mendez
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, USA
| | - Adam Wilson
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, USA
| | - Brendan Pinto
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI, USA
| | - Tony Gamble
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI, USA
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA
- Bell Museum of Natural History, University of Minnesota, St. Paul, MN, USA
| | - Marc Tollis
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, USA
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Zhao P, Peng C, Fang L, Wang Z, Liu GE. Taming transposable elements in livestock and poultry: a review of their roles and applications. Genet Sel Evol 2023; 55:50. [PMID: 37479995 PMCID: PMC10362595 DOI: 10.1186/s12711-023-00821-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 06/30/2023] [Indexed: 07/23/2023] Open
Abstract
Livestock and poultry play a significant role in human nutrition by converting agricultural by-products into high-quality proteins. To meet the growing demand for safe animal protein, genetic improvement of livestock must be done sustainably while minimizing negative environmental impacts. Transposable elements (TE) are important components of livestock and poultry genomes, contributing to their genetic diversity, chromatin states, gene regulatory networks, and complex traits of economic value. However, compared to other species, research on TE in livestock and poultry is still in its early stages. In this review, we analyze 72 studies published in the past 20 years, summarize the TE composition in livestock and poultry genomes, and focus on their potential roles in functional genomics. We also discuss bioinformatic tools and strategies for integrating multi-omics data with TE, and explore future directions, feasibility, and challenges of TE research in livestock and poultry. In addition, we suggest strategies to apply TE in basic biological research and animal breeding. Our goal is to provide a new perspective on the importance of TE in livestock and poultry genomes.
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Affiliation(s)
- Pengju Zhao
- Hainan Institute of Zhejiang University, Hainan Sanya, 572000, China
- College of Animal Sciences, Zhejiang University, Zhejiang, Hangzhou, People's Republic of China
| | - Chen Peng
- Hainan Institute of Zhejiang University, Hainan Sanya, 572000, China
- College of Animal Sciences, Zhejiang University, Zhejiang, Hangzhou, People's Republic of China
| | - Lingzhao Fang
- Center for Quantitative Genetics and Genomics, Aarhus University, 8000, Aarhus, Denmark.
| | - Zhengguang Wang
- Hainan Institute of Zhejiang University, Hainan Sanya, 572000, China.
- College of Animal Sciences, Zhejiang University, Zhejiang, Hangzhou, People's Republic of China.
| | - George E Liu
- Animal Genomics and Improvement Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD, 20705, USA.
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Martelossi J, Nicolini F, Subacchi S, Pasquale D, Ghiselli F, Luchetti A. Multiple and diversified transposon lineages contribute to early and recent bivalve genome evolution. BMC Biol 2023; 21:145. [PMID: 37365567 DOI: 10.1186/s12915-023-01632-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 05/25/2023] [Indexed: 06/28/2023] Open
Abstract
BACKGROUND Transposable elements (TEs) can represent one of the major sources of genomic variation across eukaryotes, providing novel raw materials for species diversification and innovation. While considerable effort has been made to study their evolutionary dynamics across multiple animal clades, molluscs represent a substantially understudied phylum. Here, we take advantage of the recent increase in mollusc genomic resources and adopt an automated TE annotation pipeline combined with a phylogenetic tree-based classification, as well as extensive manual curation efforts, to characterize TE repertories across 27 bivalve genomes with a particular emphasis on DDE/D class II elements, long interspersed nuclear elements (LINEs), and their evolutionary dynamics. RESULTS We found class I elements as highly dominant in bivalve genomes, with LINE elements, despite less represented in terms of copy number per genome, being the most common retroposon group covering up to 10% of their genome. We mined 86,488 reverse transcriptases (RVT) containing LINE coming from 12 clades distributed across all known superfamilies and 14,275 class II DDE/D-containing transposons coming from 16 distinct superfamilies. We uncovered a previously underestimated rich and diverse bivalve ancestral transposon complement that could be traced back to their most recent common ancestor that lived ~ 500 Mya. Moreover, we identified multiple instances of lineage-specific emergence and loss of different LINEs and DDE/D lineages with the interesting cases of CR1- Zenon, Proto2, RTE-X, and Academ elements that underwent a bivalve-specific amplification likely associated with their diversification. Finally, we found that this LINE diversity is maintained in extant species by an equally diverse set of long-living and potentially active elements, as suggested by their evolutionary history and transcription profiles in both male and female gonads. CONCLUSIONS We found that bivalves host an exceptional diversity of transposons compared to other molluscs. Their LINE complement could mainly follow a "stealth drivers" model of evolution where multiple and diversified families are able to survive and co-exist for a long period of time in the host genome, potentially shaping both recent and early phases of bivalve genome evolution and diversification. Overall, we provide not only the first comparative study of TE evolutionary dynamics in a large but understudied phylum such as Mollusca, but also a reference library for ORF-containing class II DDE/D and LINE elements, which represents an important genomic resource for their identification and characterization in novel genomes.
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Affiliation(s)
- Jacopo Martelossi
- Department of Biological Geological and Environmental Science, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
| | - Filippo Nicolini
- Department of Biological Geological and Environmental Science, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
- Fano Marine Center, Department of Biological, Geological and Environmental Sciences, University of Bologna, Viale Adriatico 1/N, 61032, Fano, Italy
| | - Simone Subacchi
- Department of Biological Geological and Environmental Science, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
| | - Daniela Pasquale
- Department of Biological Geological and Environmental Science, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
| | - Fabrizio Ghiselli
- Department of Biological Geological and Environmental Science, University of Bologna, Via Selmi 3, 40126, Bologna, Italy.
| | - Andrea Luchetti
- Department of Biological Geological and Environmental Science, University of Bologna, Via Selmi 3, 40126, Bologna, Italy
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Wang Z, Reid AMA, Wilson PW, Dunn IC. Identification of the Core Promoter and Variants Regulating Chicken CCKAR Expression. Genes (Basel) 2022; 13:1083. [PMID: 35741846 PMCID: PMC9222909 DOI: 10.3390/genes13061083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/15/2022] [Accepted: 06/15/2022] [Indexed: 02/05/2023] Open
Abstract
Decreased expression of chicken cholecystokinin A receptor (CCKAR) attenuates satiety, which contributes to increased food intake and growth for modern broilers. The study aims to define the core promoter of CCKAR, and to identify variants associated with expression activity. A 21 kb region around the CCKAR was re-sequenced to detect sequence variants. A series of 5'-deleted promoter plasmids were constructed to define the core promoter of CCKAR. The effects of sequence variants located in promoter (PSNP) and conserved (CSNP) regions on promoter activity were analyzed by comparing luciferase activity between haplotypes. A total of 182 variants were found in the 21 kb region. There were no large structural variants around CCKAR. pNL-328/+183, the one with the shortest insertion, showed the highest activity among the six promoter constructs, implying that the key cis elements regulating CCKAR expression are mainly distributed 328 bp upstream. We detected significant activity differences between high- and low-growth associated haplotypes in four of the six promoter constructs. The high-growth haplotypes of constructs pNL-1646/+183, pNL-799/+183 and pNL-528/+183 showed lower activities than the low-growth haplotypes, which is consistent with decreased expression of CCKAR in high-growth chickens. Lower expression of the high-growth allele was also detected for the CSNP5-containing construct. The data suggest that the core promoter of CCKAR is located the 328 bp region upstream from the transcription start site. Lower expression activities shown by the high-growth haplotypes in the reporter assay suggest that CSNP5 and variants located between 328 bp and 1646 bp upstream form a promising molecular basis for decreased expression of CCKAR and increased growth in chickens.
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Affiliation(s)
- Zhepeng Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China
- Royal (Dick) School of Veterinary Studies, Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, UK; (A.M.A.R.); (P.W.W.); (I.C.D.)
| | - Angus M. A. Reid
- Royal (Dick) School of Veterinary Studies, Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, UK; (A.M.A.R.); (P.W.W.); (I.C.D.)
| | - Peter W. Wilson
- Royal (Dick) School of Veterinary Studies, Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, UK; (A.M.A.R.); (P.W.W.); (I.C.D.)
| | - Ian C. Dunn
- Royal (Dick) School of Veterinary Studies, Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, UK; (A.M.A.R.); (P.W.W.); (I.C.D.)
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Wilcox JJS, Arca-Ruibal B, Samour J, Mateuta V, Idaghdour Y, Boissinot S. Linked-Read Sequencing of Eight Falcons Reveals a Unique Genomic Architecture in Flux. Genome Biol Evol 2022; 14:evac090. [PMID: 35700227 PMCID: PMC9214253 DOI: 10.1093/gbe/evac090] [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] [Received: 11/12/2021] [Revised: 05/27/2022] [Accepted: 06/06/2022] [Indexed: 11/12/2022] Open
Abstract
Falcons are diverse birds of cultural and economic importance. They have undergone major lineage-specific chromosomal rearrangements, resulting in greatly-reduced chromosome counts relative to other birds. Here, we use 10X Genomics linked reads to provide new high-contiguity genomes for two gyrfalcons, a saker falcon, a lanner falcon, three subspecies of peregrine falcons, and the common kestrel. Assisted by a transcriptome sequenced from 22 gyrfalcon tissues, we annotate these genomes for a variety of genomic features, estimate historical demography, and then investigate genomic equilibrium in the context of falcon-specific chromosomal rearrangements. We find that falcon genomes are not in AT-GC equilibrium with a bias in substitutions towards higher AT content; this bias is predominantly but not exclusively driven by hypermutability of CpG sites. Small indels and large structural variants were also biased towards insertions rather than deletions. Patterns of disequilibrium were linked to chromosomal rearrangements: falcons have lost GC content in regions that have fused to larger chromosomes from microchromosomes and gained GC content in regions of macrochromosomes that have translocated to microchromosomes. Inserted bases have accumulated on regions ancestrally belonging to microchromosomes, consistent with insertion-biased gene conversion. We also find an excess of interspersed repeats on regions of microchromosomes that have fused to macrochromosomes. Our results reveal that falcon genomes are in a state of flux. They further suggest that many of the key differences between microchromosomes and macrochromosomes are driven by differences in chromosome size, and indicate a clear role for recombination and biased-gene-conversion in determining genomic equilibrium.
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Affiliation(s)
- Justin J S Wilcox
- Center for Genomics & Systems Biology, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
| | | | - Jaime Samour
- Wildlife Management and Falcon Medicine and Breeding Consultancy, Abu Dhabi, United Arab Emirates
| | | | - Youssef Idaghdour
- Center for Genomics & Systems Biology, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
- Biology Program, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
| | - Stéphane Boissinot
- Center for Genomics & Systems Biology, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
- Biology Program, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
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