1
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Bredemeyer KR, Hillier L, Harris AJ, Hughes GM, Foley NM, Lawless C, Carroll RA, Storer JM, Batzer MA, Rice ES, Davis BW, Raudsepp T, O'Brien SJ, Lyons LA, Warren WC, Murphy WJ. Single-haplotype comparative genomics provides insights into lineage-specific structural variation during cat evolution. Nat Genet 2023; 55:1953-1963. [PMID: 37919451 PMCID: PMC10845050 DOI: 10.1038/s41588-023-01548-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/20/2023] [Indexed: 11/04/2023]
Abstract
The role of structurally dynamic genomic regions in speciation is poorly understood due to challenges inherent in diploid genome assembly. Here we reconstructed the evolutionary dynamics of structural variation in five cat species by phasing the genomes of three interspecies F1 hybrids to generate near-gapless single-haplotype assemblies. We discerned that cat genomes have a paucity of segmental duplications relative to great apes, explaining their remarkable karyotypic stability. X chromosomes were hotspots of structural variation, including enrichment with inversions in a large recombination desert with characteristics of a supergene. The X-linked macrosatellite DXZ4 evolves more rapidly than 99.5% of the genome clarifying its role in felid hybrid incompatibility. Resolved sensory gene repertoires revealed functional copy number changes associated with ecomorphological adaptations, sociality and domestication. This study highlights the value of gapless genomes to reveal structural mechanisms underpinning karyotypic evolution, reproductive isolation and ecological niche adaptation.
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Affiliation(s)
- Kevin R Bredemeyer
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Interdisciplinary Program in Genetics & Genomics, Texas A&M University, College Station, TX, USA
| | - LaDeana Hillier
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Andrew J Harris
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Interdisciplinary Program in Genetics & Genomics, Texas A&M University, College Station, TX, USA
| | - Graham M Hughes
- School of Biology & Environmental Sciences, University College Dublin, Dublin, Ireland
| | - Nicole M Foley
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
| | - Colleen Lawless
- School of Biology & Environmental Sciences, University College Dublin, Dublin, Ireland
| | - Rachel A Carroll
- Department of Animal Sciences, University of Missouri, Columbia, MO, USA
| | | | - Mark A Batzer
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - Edward S Rice
- Department of Animal Sciences, University of Missouri, Columbia, MO, USA
| | - Brian W Davis
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Interdisciplinary Program in Genetics & Genomics, Texas A&M University, College Station, TX, USA
| | - Terje Raudsepp
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA
- Interdisciplinary Program in Genetics & Genomics, Texas A&M University, College Station, TX, USA
| | - Stephen J O'Brien
- Guy Harvey Oceanographic Center, Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Leslie A Lyons
- Department of Veterinary Medicine & Surgery, University of Missouri, Columbia, MO, USA
| | - Wesley C Warren
- Department of Animal Sciences, University of Missouri, Columbia, MO, USA.
| | - William J Murphy
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, USA.
- Interdisciplinary Program in Genetics & Genomics, Texas A&M University, College Station, TX, USA.
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2
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Brovkina MV, Chapman MA, Holding ML, Clowney EJ. Emergence and influence of sequence bias in evolutionarily malleable, mammalian tandem arrays. BMC Biol 2023; 21:179. [PMID: 37612705 PMCID: PMC10463633 DOI: 10.1186/s12915-023-01673-4] [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: 04/25/2023] [Accepted: 08/01/2023] [Indexed: 08/25/2023] Open
Abstract
BACKGROUND The radiation of mammals at the extinction of the dinosaurs produced a plethora of new forms-as diverse as bats, dolphins, and elephants-in only 10-20 million years. Behind the scenes, adaptation to new niches is accompanied by extensive innovation in large families of genes that allow animals to contact the environment, including chemosensors, xenobiotic enzymes, and immune and barrier proteins. Genes in these "outward-looking" families are allelically diverse among humans and exhibit tissue-specific and sometimes stochastic expression. RESULTS Here, we show that these tandem arrays of outward-looking genes occupy AT-biased isochores and comprise the "tissue-specific" gene class that lack CpG islands in their promoters. Models of mammalian genome evolution have not incorporated the sharply different functions and transcriptional patterns of genes in AT- versus GC-biased regions. To examine the relationship between gene family expansion, sequence content, and allelic diversity, we use population genetic data and comparative analysis. First, we find that AT bias can emerge during evolutionary expansion of gene families in cis. Second, human genes in AT-biased isochores or with GC-poor promoters experience relatively low rates of de novo point mutation today but are enriched for non-synonymous variants. Finally, we find that isochores containing gene clusters exhibit low rates of recombination. CONCLUSIONS Our analyses suggest that tolerance of non-synonymous variation and low recombination are two forces that have produced the depletion of GC bases in outward-facing gene arrays. In turn, high AT content exerts a profound effect on their chromatin organization and transcriptional regulation.
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Affiliation(s)
- Margarita V Brovkina
- Graduate Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Margaret A Chapman
- Neurosciences Graduate Program, University of Michigan Medical School, Ann Arbor, MI, USA
| | | | - E Josephine Clowney
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA.
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3
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Cho YS, Jun JH, Kim JA, Kim HM, Chung O, Kang SG, Park JY, Kim HJ, Kim S, Kim HJ, Jang JH, Na KJ, Kim J, Park SG, Lee HY, Manica A, Mindell DP, Fuchs J, Edwards JS, Weber JA, Witt CC, Yeo JH, Kim S, Bhak J. Raptor genomes reveal evolutionary signatures of predatory and nocturnal lifestyles. Genome Biol 2019; 20:181. [PMID: 31464627 PMCID: PMC6714440 DOI: 10.1186/s13059-019-1793-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 08/13/2019] [Indexed: 01/11/2023] Open
Abstract
Background Birds of prey (raptors) are dominant apex predators in terrestrial communities, with hawks (Accipitriformes) and falcons (Falconiformes) hunting by day and owls (Strigiformes) hunting by night. Results Here, we report new genomes and transcriptomes for 20 species of birds, including 16 species of birds of prey, and high-quality reference genomes for the Eurasian eagle-owl (Bubo bubo), oriental scops owl (Otus sunia), eastern buzzard (Buteo japonicus), and common kestrel (Falco tinnunculus). Our extensive genomic analysis and comparisons with non-raptor genomes identify common molecular signatures that underpin anatomical structure and sensory, muscle, circulatory, and respiratory systems related to a predatory lifestyle. Compared with diurnal birds, owls exhibit striking adaptations to the nocturnal environment, including functional trade-offs in the sensory systems, such as loss of color vision genes and selection for enhancement of nocturnal vision and other sensory systems that are convergent with other nocturnal avian orders. Additionally, we find that a suite of genes associated with vision and circadian rhythm are differentially expressed in blood tissue between nocturnal and diurnal raptors, possibly indicating adaptive expression change during the transition to nocturnality. Conclusions Overall, raptor genomes show genomic signatures associated with the origin and maintenance of several specialized physiological and morphological features essential to be apex predators. Electronic supplementary material The online version of this article (10.1186/s13059-019-1793-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | - Jung A Kim
- Biological and Genetic Resources Assessment Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Hak-Min Kim
- Korean Genomics Industrialization Center (KOGIC), Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea.,Department of Biomedical Engineering, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | | | - Seung-Gu Kang
- Animal Resources Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Jin-Young Park
- Animal Resources Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Hwa-Jung Kim
- Animal Resources Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Sunghyun Kim
- Strategic Planning Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Hee-Jong Kim
- Chungnam Wild Animal Rescue Center, Kongju National University, Yesan, Republic of Korea
| | - Jin-Ho Jang
- Chungnam Wild Animal Rescue Center, Kongju National University, Yesan, Republic of Korea
| | - Ki-Jeong Na
- College of veterinary medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Jeongho Kim
- Medical care team, Cheongju Zoo, Cheongju, Republic of Korea
| | - Seung Gu Park
- Korean Genomics Industrialization Center (KOGIC), Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | | | - Andrea Manica
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - David P Mindell
- Museum of Vertebrate Zoology, University of California, Berkeley, CA, USA
| | - Jérôme Fuchs
- Institut Systématique Evolution Biodiversité (ISYEB), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, EPHE, Paris, France
| | - Jeremy S Edwards
- Chemistry and Chemical Biology, UNM Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM, USA
| | - Jessica A Weber
- Museum of Southwestern Biology and Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Christopher C Witt
- Museum of Southwestern Biology and Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Joo-Hong Yeo
- Biological and Genetic Resources Assessment Division, National Institute of Biological Resources, Incheon, Republic of Korea
| | - Soonok Kim
- Biological and Genetic Resources Assessment Division, National Institute of Biological Resources, Incheon, Republic of Korea.
| | - Jong Bhak
- Clinomics Inc, Ulsan, Republic of Korea. .,Korean Genomics Industrialization Center (KOGIC), Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea. .,Department of Biomedical Engineering, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea.
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4
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Niimura Y, Matsui A, Touhara K. Acceleration of Olfactory Receptor Gene Loss in Primate Evolution: Possible Link to Anatomical Change in Sensory Systems and Dietary Transition. Mol Biol Evol 2019; 35:1437-1450. [PMID: 29659972 DOI: 10.1093/molbev/msy042] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Primates have traditionally been regarded as vision-oriented animals with low olfactory ability, though this "microsmatic primates" view has been challenged recently. To clarify when and how degeneration of the olfactory system occurred and to specify the relevant factors during primate evolution, we here examined the olfactory receptor (OR) genes from 24 phylogenetically and ecologically diverse primate species. The results revealed that strepsirrhines with curved noses had functional OR gene repertoires that were nearly twice as large as those for haplorhines with simple noses. Neither activity pattern (nocturnal/diurnal) nor color vision system showed significant correlation with the number of functional OR genes while phylogeny and nose structure (haplorhine/strepsirrhine) are statistically controlled, but extent of folivory did. We traced the evolutionary fates of individual OR genes by identifying orthologous gene groups, demonstrating that the rates of OR gene losses were accelerated at the ancestral branch of haplorhines, which coincided with the acquisition of acute vision. The highest rate of OR gene loss was observed at the ancestral branch of leaf-eating colobines; this reduction is possibly linked with the dietary transition from frugivory to folivory because odor information is essential for fruit foraging but less so for leaf foraging. Intriguingly, we found accelerations of OR gene losses in an external branch to every hominoid species examined. These findings suggest that the current OR gene repertoire in each species has been shaped by a complex interplay of phylogeny, anatomy, and habitat; therefore, multiple factors may contribute to the olfactory degeneration in primates.
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Affiliation(s)
- Yoshihito Niimura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo, Japan.,Lead Contact
| | - Atsushi Matsui
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo, Japan
| | - Kazushige Touhara
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo, Japan
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5
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Mohajeri K, Cantsilieris S, Huddleston J, Nelson BJ, Coe BP, Campbell CD, Baker C, Harshman L, Munson KM, Kronenberg ZN, Kremitzki M, Raja A, Catacchio CR, Graves TA, Wilson RK, Ventura M, Eichler EE. Interchromosomal core duplicons drive both evolutionary instability and disease susceptibility of the Chromosome 8p23.1 region. Genome Res 2016; 26:1453-1467. [PMID: 27803192 PMCID: PMC5088589 DOI: 10.1101/gr.211284.116] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Accepted: 09/12/2016] [Indexed: 12/13/2022]
Abstract
Recurrent rearrangements of Chromosome 8p23.1 are associated with congenital heart defects and developmental delay. The complexity of this region has led to inconsistencies in the current reference assembly, confounding studies of genetic variation. Using comparative sequence-based approaches, we generated a high-quality 6.3-Mbp alternate reference assembly of an inverted Chromosome 8p23.1 haplotype. Comparison with nonhuman primates reveals a 746-kbp duplicative transposition and two separate inversion events that arose in the last million years of human evolution. The breakpoints associated with these rearrangements map to an ape-specific interchromosomal core duplicon that clusters at sites of evolutionary inversion (P = 7.8 × 10−5). Refinement of microdeletion breakpoints identifies a subgroup of patients that map to the same interchromosomal core involved in the evolutionary formation of the duplication blocks. Our results define a higher-order genomic instability element that has shaped the structure of specific chromosomes during primate evolution contributing to rearrangements associated with inversion and disease.
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Affiliation(s)
- Kiana Mohajeri
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Stuart Cantsilieris
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - John Huddleston
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA.,Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA
| | - Bradley J Nelson
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Bradley P Coe
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Catarina D Campbell
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Carl Baker
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Lana Harshman
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Katherine M Munson
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Zev N Kronenberg
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA
| | - Milinn Kremitzki
- The McDonnell Genome Institute at Washington University, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Archana Raja
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA.,Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA
| | | | - Tina A Graves
- The McDonnell Genome Institute at Washington University, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Richard K Wilson
- The McDonnell Genome Institute at Washington University, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Mario Ventura
- Dipartimento di Biologia, Università degli Studi di Bari Aldo Moro, Bari 70125, Italy
| | - Evan E Eichler
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, Washington 98195, USA.,Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA
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6
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Abstract
The recent availability of multiple avian genomes has laid the foundation for a huge variety of comparative genomics analyses including scans for changes and signatures of selection that arose from adaptions to new ecological niches. Nocturnal adaptation in birds, unlike in mammals, is comparatively recent, a fact that makes birds good candidates for identifying early genetic changes that support adaptation to dim-light environments. In this review, we give examples of comparative genomics analyses that could shed light on mechanisms of adaptation to nocturnality. We present advantages and disadvantages of both "data-driven" and "hypothesis-driven" approaches that lead to the discovery of candidate genes and genetic changes promoting nocturnality. We anticipate that the accessibility of multiple genomes from the Genome 10K Project will allow a better understanding of evolutionary mechanisms and adaptation in general.
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Affiliation(s)
- Diana Le Duc
- Medical Faculty, Rudolf Schönheimer Institute of Biochemistry, University of Leipzig, Leipzig, Germany.,Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Torsten Schöneberg
- Medical Faculty, Rudolf Schönheimer Institute of Biochemistry, University of Leipzig, Leipzig, Germany
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7
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Niimura Y, Matsui A, Touhara K. Extreme expansion of the olfactory receptor gene repertoire in African elephants and evolutionary dynamics of orthologous gene groups in 13 placental mammals. Genome Res 2014; 24:1485-96. [PMID: 25053675 PMCID: PMC4158756 DOI: 10.1101/gr.169532.113] [Citation(s) in RCA: 204] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Olfactory receptors (ORs) detect odors in the environment, and OR genes constitute the largest multigene family in mammals. Numbers of OR genes vary greatly among species—reflecting the respective species' lifestyles—and this variation is caused by frequent gene gains and losses during evolution. However, whether the extent of gene gains/losses varies among individual gene lineages and what might generate such variation is unknown. To answer these questions, we used a newly developed phylogeny-based method to classify >10,000 intact OR genes from 13 placental mammal species into 781 orthologous gene groups (OGGs); we then compared the OGGs. Interestingly, African elephants had a surprisingly large repertoire (∼2000) of functional OR genes encoded in enlarged gene clusters. Additionally, OR gene lineages that experienced more gene duplication had weaker purifying selection, and Class II OR genes have evolved more dynamically than those in Class I. Some OGGs were highly expanded in a lineage-specific manner, while only three OGGs showed complete one-to-one orthology among the 13 species without any gene gains/losses. These three OGGs also exhibited highly conserved amino acid sequences; therefore, ORs in these OGGs may have physiologically important functions common to every placental mammal. This study provides a basis for inferring OR functions from evolutionary trajectory.
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Affiliation(s)
- Yoshihito Niimura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan; ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo 113-8657, Japan
| | - Atsushi Matsui
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan; ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo 113-8657, Japan
| | - Kazushige Touhara
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan; ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, Tokyo 113-8657, Japan
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8
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Ebert G, Steininger A, Weißmann R, Boldt V, Lind-Thomsen A, Grune J, Badelt S, Heßler M, Peiser M, Hitzler M, Jensen LR, Müller I, Hu H, Arndt PF, Kuss AW, Tebel K, Ullmann R. Distribution of segmental duplications in the context of higher order chromatin organisation of human chromosome 7. BMC Genomics 2014; 15:537. [PMID: 24973960 PMCID: PMC4092221 DOI: 10.1186/1471-2164-15-537] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 06/17/2014] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Segmental duplications (SDs) are not evenly distributed along chromosomes. The reasons for this biased susceptibility to SD insertion are poorly understood. Accumulation of SDs is associated with increased genomic instability, which can lead to structural variants and genomic disorders such as the Williams-Beuren syndrome. Despite these adverse effects, SDs have become fixed in the human genome. Focusing on chromosome 7, which is particularly rich in interstitial SDs, we have investigated the distribution of SDs in the context of evolution and the three dimensional organisation of the chromosome in order to gain insights into the mutual relationship of SDs and chromatin topology. RESULTS Intrachromosomal SDs preferentially accumulate in those segments of chromosome 7 that are homologous to marmoset chromosome 2. Although this formerly compact segment has been re-distributed to three different sites during primate evolution, we can show by means of public data on long distance chromatin interactions that these three intervals, and consequently the paralogous SDs mapping to them, have retained their spatial proximity in the nucleus. Focusing on SD clusters implicated in the aetiology of the Williams-Beuren syndrome locus we demonstrate by cross-species comparison that these SDs have inserted at the borders of a topological domain and that they flank regions with distinct DNA conformation. CONCLUSIONS Our study suggests a link of nuclear architecture and the propagation of SDs across chromosome 7, either by promoting regional SD insertion or by contributing to the establishment of higher order chromatin organisation themselves. The latter could compensate for the high risk of structural rearrangements and thus may have contributed to their evolutionary fixation in the human genome.
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Affiliation(s)
- Grit Ebert
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
- />Department of Biology, Chemistry and Pharmacy, Free University Berlin, 14195 Berlin, Germany
| | - Anne Steininger
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
- />Department of Biology, Chemistry and Pharmacy, Free University Berlin, 14195 Berlin, Germany
| | - Robert Weißmann
- />Department of Human Genetics, University Medicine Greifswald, and Interfaculty Institute of Genetics and Functional Genomics, University of Greifswald, Fleischmannstraße 42-44, 17475 Greifswald, Germany
| | - Vivien Boldt
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
- />Department of Biology, Chemistry and Pharmacy, Free University Berlin, 14195 Berlin, Germany
| | - Allan Lind-Thomsen
- />Wilhelm Johannsen Centre for Functional Genome Research, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen, Denmark
| | - Jana Grune
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Stefan Badelt
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
- />Institute for Theoretical Chemistry, University of Vienna, Waehringer Straße 17, A-1090 Vienna, Austria
| | - Melanie Heßler
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Matthias Peiser
- />Unit Experimental Research, Department of Product Safety, Federal Institute for Bundeswehr Institute of Radiobiology affiliated, the University of Ulm, Neuherbergstraße 11, 80937 Munich, Germany
| | - Manuel Hitzler
- />Unit Experimental Research, Department of Product Safety, Federal Institute for Bundeswehr Institute of Radiobiology affiliated, the University of Ulm, Neuherbergstraße 11, 80937 Munich, Germany
| | - Lars R Jensen
- />Department of Human Genetics, University Medicine Greifswald, and Interfaculty Institute of Genetics and Functional Genomics, University of Greifswald, Fleischmannstraße 42-44, 17475 Greifswald, Germany
| | - Ines Müller
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Hao Hu
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Peter F Arndt
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Andreas W Kuss
- />Department of Human Genetics, University Medicine Greifswald, and Interfaculty Institute of Genetics and Functional Genomics, University of Greifswald, Fleischmannstraße 42-44, 17475 Greifswald, Germany
| | - Katrin Tebel
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Reinhard Ullmann
- />Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
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9
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Shadravan F. Sex bias in copy number variation of olfactory receptor gene family depends on ethnicity. Front Genet 2013; 4:32. [PMID: 23503716 PMCID: PMC3596775 DOI: 10.3389/fgene.2013.00032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 02/26/2013] [Indexed: 12/22/2022] Open
Abstract
Gender plays a pivotal role in the human genetic identity and is also manifested in many genetic disorders particularly mental retardation. In this study its effect on copy number variation (CNV), known to cause genetic disorders was explored. As the olfactory receptor (OR) repertoire comprises the largest human gene family, it was selected for this study, which was carried out within and between three populations, derived from 150 individuals from the 1000 Genome Project. Analysis of 3872 CNVs detected among 791 OR loci, in which 307 loci showed CNV, revealed the following novel findings: Sex bias in CNV was significantly more prevalent in uncommon than common CNV variants of OR pseudogenes, in which the male genome showed more CNVs; and in one-copy number loss compared to complete deletion of OR pseudogenes; both findings implying a more recent evolutionary role for gender. Sex bias in copy number gain was also detected. Another novel finding was that the observed sex bias was largely dependent on ethnicity and was in general absent in East Asians. Using a CNV public database for sick children (International Standard Cytogenomic Array Consortium) the application of these findings for improving clinical molecular diagnostics is discussed by showing an example of sex bias in CNV among kids with autism. Additional clinical relevance is discussed, as the most polymorphic CNV-enriched OR cluster in the human genome, located on chr 15q11.2, is found near the Prader–Willi syndrome/Angelman syndrome bi-directionally imprinted region associated with two well-known mental retardation syndromes. As olfaction represents the primitive cognition in most mammals, arguably in competition with the development of a larger brain, the extensive retention of OR pseudogenes in females of this study, might point to a parent-of-origin indirect regulatory role for OR pseudogenes in the embryonic development of human brain. Thus any perturbation in the temporal regulation of olfactory system could lead to developmental delay disorders including mental retardation.
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Affiliation(s)
- Farideh Shadravan
- *Correspondence: Farideh Shadravan, 2584 San Jose Ave, San Francisco, CA 94112, USA. e-mail:
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10
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Marzo M, Bello X, Puig M, Maside X, Ruiz A. Striking structural dynamism and nucleotide sequence variation of the transposon Galileo in the genome of Drosophila mojavensis. Mob DNA 2013; 4:6. [PMID: 23374229 PMCID: PMC3573991 DOI: 10.1186/1759-8753-4-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 11/26/2012] [Indexed: 01/25/2023] Open
Abstract
Background Galileo is a transposable element responsible for the generation of three chromosomal inversions in natural populations of Drosophila buzzatii. Although the most characteristic feature of Galileo is the long internally-repetitive terminal inverted repeats (TIRs), which resemble the Drosophila Foldback element, its transposase-coding sequence has led to its classification as a member of the P-element superfamily (Class II, subclass 1, TIR order). Furthermore, Galileo has a wide distribution in the genus Drosophila, since it has been found in 6 of the 12 Drosophila sequenced genomes. Among these species, D. mojavensis, the one closest to D. buzzatii, presented the highest diversity in sequence and structure of Galileo elements. Results In the present work, we carried out a thorough search and annotation of all the Galileo copies present in the D. mojavensis sequenced genome. In our set of 170 Galileo copies we have detected 5 Galileo subfamilies (C, D, E, F, and X) with different structures ranging from nearly complete, to only 2 TIR or solo TIR copies. Finally, we have explored the structural and length variation of the Galileo copies that point out the relatively frequent rearrangements within and between Galileo elements. Different mechanisms responsible for these rearrangements are discussed. Conclusions Although Galileo is a transposable element with an ancient history in the D. mojavensis genome, our data indicate a recent transpositional activity. Furthermore, the dynamism in sequence and structure, mainly affecting the TIRs, suggests an active exchange of sequences among the copies. This exchange could lead to new subfamilies of the transposon, which could be crucial for the long-term survival of the element in the genome.
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Affiliation(s)
- Mar Marzo
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Catalunya, 08193, Spain.
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11
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Genetics of canine olfaction and receptor diversity. Mamm Genome 2011; 23:132-43. [PMID: 22080304 DOI: 10.1007/s00335-011-9371-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 10/23/2011] [Indexed: 01/06/2023]
Abstract
Olfaction is a particularly important sense in the dog. Humans selected for this capacity during the domestication process, and selection has continued to be employed to enhance this ability. In this review we first describe the different olfactory systems that exist and the different odorant receptors that are expressed in those systems. We then focus on the dog olfactory receptors by describing the olfactory receptor gene repertoire and its polymorphisms. Finally, we discuss the different uses of dog olfaction and the questions that still need to be studied.
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12
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Abstract
The first wave of personal genomes documents how no single individual genome contains the full complement of functional genes. Here, we describe the extent of variation in gene and pseudogene numbers between individuals arising from inactivation events such as premature termination or aberrant splicing due to single-nucleotide polymorphisms. This highlights the inadequacy of the current reference sequence and gene set. We present a proposal to define a reference gene set that will remain stable as more individuals are sequenced. In particular, we recommend that the ancestral allele be used to define the reference sequence from which a core human reference gene annotation set can be derived. In addition, we call for the development of an expanded gene set to include human-specific genes that have arisen recently and are absent from the ancestral set.
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Hurle B, Marques-Bonet T, Antonacci F, Hughes I, Ryan JF, Eichler EE, Ornitz DM, Green ED. Lineage-specific evolution of the vertebrate Otopetrin gene family revealed by comparative genomic analyses. BMC Evol Biol 2011; 11:23. [PMID: 21261979 PMCID: PMC3038909 DOI: 10.1186/1471-2148-11-23] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 01/24/2011] [Indexed: 11/19/2022] Open
Abstract
Background Mutations in the Otopetrin 1 gene (Otop1) in mice and fish produce an unusual bilateral vestibular pathology that involves the absence of otoconia without hearing impairment. The encoded protein, Otop1, is the only functionally characterized member of the Otopetrin Domain Protein (ODP) family; the extended sequence and structural preservation of ODP proteins in metazoans suggest a conserved functional role. Here, we use the tools of sequence- and cytogenetic-based comparative genomics to study the Otop1 and the Otop2-Otop3 genes and to establish their genomic context in 25 vertebrates. We extend our evolutionary study to include the gene mutated in Usher syndrome (USH) subtype 1G (Ush1g), both because of the head-to-tail clustering of Ush1g with Otop2 and because Otop1 and Ush1g mutations result in inner ear phenotypes. Results We established that OTOP1 is the boundary gene of an inversion polymorphism on human chromosome 4p16 that originated in the common human-chimpanzee lineage more than 6 million years ago. Other lineage-specific evolutionary events included a three-fold expansion of the Otop genes in Xenopus tropicalis and of Ush1g in teleostei fish. The tight physical linkage between Otop2 and Ush1g is conserved in all vertebrates. To further understand the functional organization of the Ushg1-Otop2 locus, we deduced a putative map of binding sites for CCCTC-binding factor (CTCF), a mammalian insulator transcription factor, from genome-wide chromatin immunoprecipitation-sequencing (ChIP-seq) data in mouse and human embryonic stem (ES) cells combined with detection of CTCF-binding motifs. Conclusions The results presented here clarify the evolutionary history of the vertebrate Otop and Ush1g families, and establish a framework for studying the possible interaction(s) of Ush1g and Otop in developmental pathways.
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Affiliation(s)
- Belen Hurle
- Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
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14
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Waszak SM, Hasin Y, Zichner T, Olender T, Keydar I, Khen M, Stütz AM, Schlattl A, Lancet D, Korbel JO. Systematic inference of copy-number genotypes from personal genome sequencing data reveals extensive olfactory receptor gene content diversity. PLoS Comput Biol 2010; 6:e1000988. [PMID: 21085617 PMCID: PMC2978733 DOI: 10.1371/journal.pcbi.1000988] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 10/05/2010] [Indexed: 12/02/2022] Open
Abstract
Copy-number variations (CNVs) are widespread in the human genome, but comprehensive assignments of integer locus copy-numbers (i.e., copy-number genotypes) that, for example, enable discrimination of homozygous from heterozygous CNVs, have remained challenging. Here we present CopySeq, a novel computational approach with an underlying statistical framework that analyzes the depth-of-coverage of high-throughput DNA sequencing reads, and can incorporate paired-end and breakpoint junction analysis based CNV-analysis approaches, to infer locus copy-number genotypes. We benchmarked CopySeq by genotyping 500 chromosome 1 CNV regions in 150 personal genomes sequenced at low-coverage. The assessed copy-number genotypes were highly concordant with our performed qPCR experiments (Pearson correlation coefficient 0.94), and with the published results of two microarray platforms (95–99% concordance). We further demonstrated the utility of CopySeq for analyzing gene regions enriched for segmental duplications by comprehensively inferring copy-number genotypes in the CNV-enriched >800 olfactory receptor (OR) human gene and pseudogene loci. CopySeq revealed that OR loci display an extensive range of locus copy-numbers across individuals, with zero to two copies in some OR loci, and two to nine copies in others. Among genetic variants affecting OR loci we identified deleterious variants including CNVs and SNPs affecting ∼15% and ∼20% of the human OR gene repertoire, respectively, implying that genetic variants with a possible impact on smell perception are widespread. Finally, we found that for several OR loci the reference genome appears to represent a minor-frequency variant, implying a necessary revision of the OR repertoire for future functional studies. CopySeq can ascertain genomic structural variation in specific gene families as well as at a genome-wide scale, where it may enable the quantitative evaluation of CNVs in genome-wide association studies involving high-throughput sequencing. Human individual genome sequencing has recently become affordable, enabling highly detailed genetic sequence comparisons. While the identification and genotyping of single-nucleotide polymorphisms has already been successfully established for different sequencing platforms, the detection, quantification and genotyping of large-scale copy-number variants (CNVs), i.e., losses or gains of long genomic segments, has remained challenging. We present a computational approach that enables detecting CNVs in sequencing data and accurately identifies the actual copy-number at which DNA segments of interest occur in an individual genome. This approach enabled us to obtain novel insights into the largest human gene family – the olfactory receptors (ORs) – involved in smell perception. While previous studies reported an abundance of CNVs in ORs, our approach enabled us to globally identify absolute differences in OR gene counts that exist between humans. While several OR genes have very high gene counts, other ORs are found only once or are missing entirely in some individuals. The latter have a particularly high probability of influencing individual differences in the perception of smell, a question that future experimental efforts can now address. Furthermore, we observed differences in OR gene counts between populations, pointing at ORs that might contribute to population-specific differences in smell.
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Affiliation(s)
- Sebastian M. Waszak
- Department of Molecular Genetics, Crown Human Genome Center, Weizmann Institute of Science, Rehovot, Israel
- Department of Biotechnology and Bioinformatics, Weihenstephan-Triesdorf University of Applied Sciences, Freising, Germany
- Genome Biology Research Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Yehudit Hasin
- Department of Molecular Genetics, Crown Human Genome Center, Weizmann Institute of Science, Rehovot, Israel
| | - Thomas Zichner
- Genome Biology Research Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Tsviya Olender
- Department of Molecular Genetics, Crown Human Genome Center, Weizmann Institute of Science, Rehovot, Israel
| | - Ifat Keydar
- Department of Molecular Genetics, Crown Human Genome Center, Weizmann Institute of Science, Rehovot, Israel
| | - Miriam Khen
- Department of Molecular Genetics, Crown Human Genome Center, Weizmann Institute of Science, Rehovot, Israel
| | - Adrian M. Stütz
- Genome Biology Research Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Andreas Schlattl
- Genome Biology Research Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Doron Lancet
- Department of Molecular Genetics, Crown Human Genome Center, Weizmann Institute of Science, Rehovot, Israel
| | - Jan O. Korbel
- Genome Biology Research Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- European Bioinformatics Institute, EMBL-EBI, Hinxton, United Kingdom
- * E-mail:
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15
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Yuan Z, Sun X, Jiang D, Ding Y, Lu Z, Gong L, Liu H, Xie J. Origin and evolution of a placental-specific microRNA family in the human genome. BMC Evol Biol 2010; 10:346. [PMID: 21067568 PMCID: PMC2996404 DOI: 10.1186/1471-2148-10-346] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Accepted: 11/10/2010] [Indexed: 12/13/2022] Open
Abstract
Background MicroRNAs (miRNAs) are a class of short regulatory RNAs encoded in the genome of DNA viruses, some single cell organisms, plants and animals. With the rapid development of technology, more and more miRNAs are being discovered. However, the origin and evolution of most miRNAs remain obscure. Here we report the origin and evolution dynamics of a human miRNA family. Results We have shown that all members of the miR-1302 family are derived from MER53 elements. Although the conservation scores of the MER53-derived pre-miRNA sequences are low, we have identified 36 potential paralogs of MER53-derived miR-1302 genes in the human genome and 58 potential orthologs of the human miR-1302 family in placental mammals. We suggest that in placental species, this miRNA family has evolved following the birth-and-death model of evolution. Three possible mechanisms that can mediate miRNA duplication in evolutionary history have been proposed: the transposition of the MER53 element, segmental duplications and Alu-mediated recombination. Finally, we have found that the target genes of miR-1302 are over-represented in transportation, localization, and system development processes and in the positive regulation of cellular processes. Many of them are predicted to function in binding and transcription regulation. Conclusions The members of miR-1302 family that are derived from MER53 elements are placental-specific miRNAs. They emerged at the early stage of the recent 180 million years since eutherian mammals diverged from marsupials. Under the birth-and-death model, the miR-1302 genes have experienced a complex expansion with some members evolving by segmental duplications and some by Alu-mediated recombination events.
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Affiliation(s)
- Zhidong Yuan
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
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16
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Matsui A, Go Y, Niimura Y. Degeneration of olfactory receptor gene repertories in primates: no direct link to full trichromatic vision. Mol Biol Evol 2010; 27:1192-200. [PMID: 20061342 DOI: 10.1093/molbev/msq003] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Odor molecules in the environment are detected by olfactory receptors (ORs), being encoded by a large multigene family in mammalian genomes. It is generally thought that primates are vision oriented and dependent weakly on olfaction. Previous studies suggested that Old World monkeys (OWMs) and hominoids lost many functional OR genes after the divergence from New World monkeys (NWMs) due to the acquisition of well-developed trichromatic vision. To examine this hypothesis, here we analyzed OR gene repertoires of five primate species including NWMs, OWMs, and hominoids for which high-coverage genome sequences are available, together with two prosimians and tree shrews with low-coverage genomes. The results showed no significant differences in the number of functional OR genes between NWMs (marmosets) and OWMs/hominoids. Two independent analyses, identification of orthologous genes among the five primates and estimation of the numbers of ancestral genes by the reconciled tree method, did not support a sudden loss of OR genes at the branch of the OWMs/hominoids ancestor but suggested a gradual loss in every lineage. Moreover, we found that humans retain larger numbers of ancestral OR genes that were in the common ancestor of NWMs/OWMs/hominoids than orangutans and macaques and that the OR gene repertoire in humans is more similar to that of marmosets than those of orangutans and macaques. These results suggest that the degeneration of OR genes in primates cannot simply be explained by the acquisition of trichromatic vision, and our sense of smell may not be inferior to other primate species.
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Affiliation(s)
- Atsushi Matsui
- Department of Cellular and Molecular Biology, Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan
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17
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Li X, Slife J, Patel N, Zhao S. Stepwise evolution of two giant composite LTR-retrotransposon-like elements DA and Xiao. BMC Evol Biol 2009; 9:128. [PMID: 19500371 PMCID: PMC2700803 DOI: 10.1186/1471-2148-9-128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Accepted: 06/05/2009] [Indexed: 12/03/2022] Open
Abstract
Background We recently discovered two composite long terminal repeat (LTR)-retrotransposon-like elements which we named DA (~300 kb) and Xiao (~30 kb), meaning big and small in Chinese respectively. Xiao and DA (three types of DA identified) were found to have been derived from several donor sites and have spread to 30 loci in the human genome, totaling to 5 Mb. Our bioinformatics analyses with the released human, chimp, rhesus macaque, orangutan, and marmoset genomic sequences indicate that DA and Xiao emerged ~25 million years (Myr) ago. Results To better understand the evolution of these two complex elements, we investigated various internal junctions of DA and Xiao as well as orthologous genomic sites of the 30 DA/Xiao loci in non-human primates including great apes, lesser apes, Old World monkeys, New World monkeys, and a prosimian. We found that Xiao and type I DA first emerged in the genome between 25 and 18 Myr ago, whereas type II and Type III DAs emerged between 14 and 7 Myr ago. Xiao and DA were most active in great apes, with their amplification peaking during 25-14 and 14-7 Myr ago, respectively. Neither DA nor Xiao seem to have been active in the human and chimp genomes during last 6 Myr. Conclusion The study has led to a more accurate age determination of the DA and Xiao elements than our previous bioinformatics analyses, and indicates that the amplification activity of the elements coincided with that of group I HERV-Es during evolution. It has also illustrated an evolutionary path with stepwise structural changes for the elements during past 25 Myr, and in doing so has shed more light on these two intriguing and complex elements that have reshaped our genome.
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Affiliation(s)
- Xuanyang Li
- Department of Biochemistry and Molecular Biology, Institute of Bioinformatics, University of Georgia, Athens, GA, USA.
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18
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Doyle JJ, Flagel LE, Paterson AH, Rapp RA, Soltis DE, Soltis PS, Wendel JF. Evolutionary genetics of genome merger and doubling in plants. Annu Rev Genet 2009; 42:443-61. [PMID: 18983261 DOI: 10.1146/annurev.genet.42.110807.091524] [Citation(s) in RCA: 428] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Polyploidy is a common mode of evolution in flowering plants. The profound effects of polyploidy on gene expression appear to be caused more by hybridity than by genome doubling. Epigenetic mechanisms underlying genome-wide changes in expression are as yet poorly understood; only methylation has received much study, and its importance varies among polyploids. Genetic diploidization begins with the earliest responses to genome merger and doubling; less is known about chromosomal diploidization. Polyploidy duplicates every gene in the genome, providing the raw material for divergence or partitioning of function in homoeologous copies. Preferential retention or loss of genes occurs in a wide range of taxa, suggesting that there is an underlying set of principles governing the fates of duplicated genes. Further studies are required for general patterns to be elucidated, involving different plant families, kinds of polyploidy, and polyploids of different ages.
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Affiliation(s)
- Jeff J Doyle
- Department of Plant Biology, Cornell University, Ithaca, New York 14850, USA.
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19
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Robin S, Tacher S, Rimbault M, Vaysse A, Dréano S, André C, Hitte C, Galibert F. Genetic diversity of canine olfactory receptors. BMC Genomics 2009; 10:21. [PMID: 19144169 PMCID: PMC2635374 DOI: 10.1186/1471-2164-10-21] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Accepted: 01/14/2009] [Indexed: 11/29/2022] Open
Abstract
Background Evolution has resulted in large repertoires of olfactory receptor (OR) genes, forming the largest gene families in mammalian genomes. Knowledge of the genetic diversity of olfactory receptors is essential if we are to understand the differences in olfactory sensory capability between individuals. Canine breeds constitute an attractive model system for such investigations. Results We sequenced 109 OR genes considered representative of the whole OR canine repertoire, which consists of more than 800 genes, in a cohort of 48 dogs of six different breeds. SNP frequency showed the overall level of polymorphism to be high. However, the distribution of SNP was highly heterogeneous among OR genes. More than 50% of OR genes were found to harbour a large number of SNP, whereas the rest were devoid of SNP or only slightly polymorphic. Heterogeneity was also observed across breeds, with 25% of the SNP breed-specific. Linkage disequilibrium within OR genes and OR clusters suggested a gene conversion process, consistent with a mean level of polymorphism higher than that observed for introns and intergenic sequences. A large proportion (47%) of SNP induced amino-acid changes and the Ka/Ks ratio calculated for all alleles with a complete ORF indicated a low selective constraint with respect to the high level of redundancy of the olfactory combinatory code and an ongoing pseudogenisation process, which affects dog breeds differently. Conclusion Our demonstration of a high overall level of polymorphism, likely to modify the ligand-binding capacity of receptors distributed differently within the six breeds tested, is the first step towards understanding why Labrador Retrievers and German Shepherd Dogs have a much greater potential for use as sniffer dogs than Pekingese dogs or Greyhounds. Furthermore, the heterogeneity in OR polymorphism observed raises questions as to why, in a context in which most OR genes are highly polymorphic, a subset of these genes is not? This phenomenon may be related to the nature of their ligands and their importance in everyday life.
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Affiliation(s)
- Stéphanie Robin
- Institut de Génétique et Développement de Rennes, CNRS UMR 6061, Université de Rennes 1, 2 Avenue du Professeur Léon Bernard, 43 Rennes, France
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Young JM, Endicott RM, Parghi SS, Walker M, Kidd JM, Trask BJ. Extensive copy-number variation of the human olfactory receptor gene family. Am J Hum Genet 2008; 83:228-42. [PMID: 18674749 DOI: 10.1016/j.ajhg.2008.07.005] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 06/25/2008] [Accepted: 07/07/2008] [Indexed: 11/24/2022] Open
Abstract
As much as a quarter of the human genome has been reported to vary in copy number between individuals, including regions containing about half of the members of the olfactory receptor (OR) gene family. We have undertaken a detailed study of copy-number variation of ORs to elucidate the selective and mechanistic forces acting on this gene family and the true impact of copy-number variation on human OR repertoires. We argue that the properties of copy-number variants (CNVs) and other sets of large genomic regions violate the assumptions of statistical methods that are commonly used in the assessment of gene enrichment. Using more appropriate methods, we provide evidence that OR enrichment in CNVs is not due to positive selection but is because of OR preponderance in segmentally duplicated regions, which are known to be frequently copy-number variable, and because purifying selection against CNVs is lower in OR-containing regions than in regions containing essential genes. We also combine multiplex ligation-dependent probe amplification (MLPA) and PCR to assay the copy numbers of 37 candidate CNV ORs in a panel of approximately 50 human individuals. We confirm copy-number variation of 18 ORs but find no variation in this human-diversity panel for 16 other ORs, highlighting the caveat that reported intervals often overrepresent true CNVs. The copy-number variation we describe is likely to underpin significant variation in olfactory abilities among human individuals. Finally, we show that both homology-based and homology-independent processes have played a recent role in remodeling the OR family.
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Maresh A, Rodriguez Gil D, Whitman MC, Greer CA. Principles of glomerular organization in the human olfactory bulb--implications for odor processing. PLoS One 2008; 3:e2640. [PMID: 18612420 PMCID: PMC2440537 DOI: 10.1371/journal.pone.0002640] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Accepted: 06/05/2008] [Indexed: 11/19/2022] Open
Abstract
Olfactory sensory neurons (OSN) in mice express only 1 of a possible 1,100 odor receptors (OR) and axons from OSNs expressing the same odor receptor converge into ∼2 of the 1,800 glomeruli in each olfactory bulb (OB) in mice; this yields a convergence ratio that approximates 2∶1, 2 glomeruli/OR. Because humans express only 350 intact ORs, we examined human OBs to determine if the glomerular convergence ratio of 2∶1 established in mice was applicable to humans. Unexpectedly, the average number of human OB glomeruli is >5,500 yielding a convergence ratio of ∼16∶1. The data suggest that the initial coding of odor information in the human OB may differ from the models developed for rodents and that recruitment of additional glomeruli for subpopulations of ORs may contribute to more robust odor representation.
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Affiliation(s)
- Alison Maresh
- Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Diego Rodriguez Gil
- Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Mary C. Whitman
- Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Charles A. Greer
- Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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22
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Go Y, Niimura Y. Similar Numbers but Different Repertoires of Olfactory Receptor Genes in Humans and Chimpanzees. Mol Biol Evol 2008; 25:1897-907. [DOI: 10.1093/molbev/msn135] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Kuang H, Caldwell KS, Meyers BC, Michelmore RW. Frequent sequence exchanges between homologs of RPP8 in Arabidopsis are not necessarily associated with genomic proximity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 54:69-80. [PMID: 18182023 DOI: 10.1111/j.1365-313x.2008.03408.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Disease resistance (R) genes are often clustered in plant genomes and may exhibit heterogeneous rates of evolution. Some (type I R genes) have evolved rapidly through frequent sequence exchanges, while others (type II R genes) have evolved independently and tend to be conserved in different genotypes or related species. The RPP8 resistance gene in Arabidopsis thaliana is located at a complex locus that also harbors the sequence-related resistance genes HRT and RCY1 in different ecotypes. We sequenced 98 homologs of RPP8 from A. thaliana, Arabidopsis arenosa and Arabidopsis lyrata. Three lineages of type II and one lineage of type I RPP8 homologs were identified. Two of the three lineages of type II genes are each represented by a single-copy locus on either chromosomes I or V. Chromosome V contains two small clusters of RPP8 paralogs. One cluster contains both type I and type II genes and the other comprises only type I genes. These multi-copy loci have expanded and contracted through unequal crossovers, which have generated chimeric genes as well as variations in copy number. Sequence exchanges, most likely gene conversions, were detected between RPP8 homologs that are spatially separated by 2.2 Mb and 12 cM. The sequence exchanges between type I homologs within a locus have been more frequent than sequence exchanges between homologs from two different loci, indicating the influence of chromosomal position on the evolution of these R genes. However, physical distance was not the only factor determining the frequency of sequence exchange, because some closely linked paralogs exhibited little sequence exchange. At least two distinct lineages of type II RPP8 homologs were identified in different species, with obvious allelic/orthologous relationships within each lineage. Therefore, the differentiation of type I and type II RPP8 homologs seems to have occurred before speciation of A. thaliana, A. arenosa and A. lyrata.
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Affiliation(s)
- Hanhui Kuang
- The Genome Center and Department of Plant Sciences, University of California, Davis, CA 95616, USA
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24
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Ji X, Zhao S. DA and Xiao-two giant and composite LTR-retrotransposon-like elements identified in the human genome. Genomics 2008; 91:249-58. [PMID: 18083327 DOI: 10.1016/j.ygeno.2007.10.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Revised: 10/22/2007] [Accepted: 10/29/2007] [Indexed: 11/19/2022]
Abstract
We discovered two new complex elements while studying large genomic rearrangements and segmental duplications in the human genome. Both resemble bacterial composite DNA transposon Tn9, consisting of a core flanked by mobile elements, except that the flanking element is not a DNA transposon but instead is long terminal repeat retrotransposon-like with human endogenous retrovirus and satellite sequences. Based on the core size, we named them Xiao ( approximately 30 kb) and DA ( approximately 280 kb), meaning small and big, respectively, in Chinese. Xiao originated from a 19p region encoding olfactory receptor 7E members after the human/ape divergence from Old World monkeys, while DA likely evolved from a Xiao by inserting approximately 200 kb of chimeric sequence from 16p and 21q into the Xiao core, resulting in a target site duplication of 3.4 kb. DA/Xiao was identified in 30 loci on 12 chromosomes, and only DAs mediated intrachromosomal rearrangements, based on our reconstructed human-mouse-rat ancestral genome and the rhesus macaque genome.
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Affiliation(s)
- Xinglai Ji
- Department of Biochemistry and Molecular Biology, Institute of Bioinformatics, University of Georgia, Athens, GA 30602-7229, USA
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Fiston-Lavier AS, Anxolabehere D, Quesneville H. A model of segmental duplication formation in Drosophila melanogaster. Genome Res 2007; 17:1458-70. [PMID: 17726166 PMCID: PMC1987339 DOI: 10.1101/gr.6208307] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Segmental duplications (SDs) are low-copy repeats of DNA segments that have long been recognized to be involved in genome organization and evolution. But, to date, the mechanism of their formation remains obscure. We propose a model for SD formation that we name "duplication-dependent strand annealing" (DDSA). This model is a variant of the synthesis-dependent strand annealing (SDSA) model--a double-strand break (DSB) homologous repair model. DSB repair in Drosophila melanogaster genome usually occurs primarily through homologous repair, more preferentially through the SDSA model. The DDSA model predicts that after a DSB, the search for an ectopic homologous region--here a repeat--initiates the repair. As expected by the model, the analysis of SDs detected by a computational analysis of the D. melanogaster genome indicates a high enrichment in transposable elements at SD ends. It shows moreover a preferential location of SDs in heterochromatic regions. The model has the advantage of also predicting specific traces left during synthesis. The observed traces support the DDSA model as one model of formation of SDs in D. melanogaster genome. The analysis of these DDSA signatures suggests moreover a sequestration of the dissociated strand in the repair complex.
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Affiliation(s)
- Anna-Sophie Fiston-Lavier
- Laboratoire Bioinformatique et Génomique, Institut Jacques Monod, 75005 Paris, France
- Corresponding author.E-mail ; fax 33-1-4427-3660
| | - Dominique Anxolabehere
- Laboratoire Dynamique du Génome et Evolution, Institut Jacques Monod, 75005 Paris, France
| | - Hadi Quesneville
- Laboratoire Bioinformatique et Génomique, Institut Jacques Monod, 75005 Paris, France
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26
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Thomas JH. Rapid birth-death evolution specific to xenobiotic cytochrome P450 genes in vertebrates. PLoS Genet 2007; 3:e67. [PMID: 17500592 PMCID: PMC1866355 DOI: 10.1371/journal.pgen.0030067] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Accepted: 03/14/2007] [Indexed: 12/15/2022] Open
Abstract
Genes vary greatly in their long-term phylogenetic stability and there exists no general explanation for these differences. The cytochrome P450 (CYP450) gene superfamily is well suited to investigating this problem because it is large and well studied, and it includes both stable and unstable genes. CYP450 genes encode oxidase enzymes that function in metabolism of endogenous small molecules and in detoxification of xenobiotic compounds. Both types of enzymes have been intensively studied. My analysis of ten nearly complete vertebrate genomes indicates that each genome contains 50-80 CYP450 genes, which are about evenly divided between phylogenetically stable and unstable genes. The stable genes are characterized by few or no gene duplications or losses in species ranging from bony fish to mammals, whereas unstable genes are characterized by frequent gene duplications and losses (birth-death evolution) even among closely related species. All of the CYP450 genes that encode enzymes with known endogenous substrates are phylogenetically stable. In contrast, most of the unstable genes encode enzymes that function as xenobiotic detoxifiers. Nearly all unstable CYP450 genes in the mouse and human genomes reside in a few dense gene clusters, forming unstable gene islands that arose by recurrent local gene duplication. Evidence for positive selection in amino acid sequence is restricted to these unstable CYP450 genes, and sites of selection are associated with substrate-binding regions in the protein structure. These results can be explained by a general model in which phylogenetically stable genes have core functions in development and physiology, whereas unstable genes have accessory functions associated with unstable environmental interactions such as toxin and pathogen exposure. Unstable gene islands in vertebrates share some functional properties with bacterial genomic islands, though they arise by local gene duplication rather than horizontal gene transfer.
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Affiliation(s)
- James H Thomas
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America.
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27
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Shi P, Zhang J. Comparative genomic analysis identifies an evolutionary shift of vomeronasal receptor gene repertoires in the vertebrate transition from water to land. Genome Res 2007; 17:166-74. [PMID: 17210926 PMCID: PMC1781348 DOI: 10.1101/gr.6040007] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Two evolutionarily unrelated superfamilies of G-protein coupled receptors, V1Rs and V2Rs, bind pheromones and "ordinary" odorants to initiate vomeronasal chemical senses in vertebrates, which play important roles in many aspects of an organism's daily life such as mating, territoriality, and foraging. To study the macroevolution of vomeronasal sensitivity, we identified all V1R and V2R genes from the genome sequences of 11 vertebrates. Our analysis suggests the presence of multiple V1R and V2R genes in the common ancestor of teleost fish and tetrapods and reveals an exceptionally large among-species variation in the sizes of these gene repertoires. Interestingly, the ratio of the number of intact V1R genes to that of V2R genes increased by approximately 50-fold as land vertebrates evolved from aquatic vertebrates. A similar increase was found for the ratio of the number of class II odorant receptor (OR) genes to that of class I genes, but not in other vertebrate gene families. Because V1Rs and class II ORs have been suggested to bind to small airborne chemicals, whereas V2Rs and class I ORs recognize water-soluble molecules, these increases reflect a rare case of adaptation to terrestrial life at the gene family level. Several gene families known to function in concert with V2Rs in the mouse are absent outside rodents, indicating rapid changes of interactions between vomeronasal receptors and their molecular partners. Taken together, our results demonstrate the exceptional evolutionary fluidity of vomeronasal receptors, making them excellent targets for studying the molecular basis of physiological and behavioral diversity and adaptation.
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Affiliation(s)
- Peng Shi
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
- Corresponding author.E-mail ; fax (734) 763-0544
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28
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Gibcus JH, Kok K, Menkema L, Hermsen MA, Mastik M, Kluin PM, van der Wal JE, Schuuring E. High-resolution mapping identifies a commonly amplified 11q13.3 region containing multiple genes flanked by segmental duplications. Hum Genet 2006; 121:187-201. [PMID: 17171571 DOI: 10.1007/s00439-006-0299-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Accepted: 11/09/2006] [Indexed: 11/28/2022]
Abstract
DNA amplification of the 11q13 region is observed frequently in many carcinomas. Within the amplified region several candidate oncogenes have been mapped, including cyclin D1, TAOS1 and cortactin. Yet, it is unknown which gene(s) is/are responsible for the selective pressure enabling amplicon formation. This is probably due to the use of low-resolution detection methods. Furthermore, the size and structure of the amplified 11q13 region is complex and consists of multiple amplicon cores that differ between different tumor types. We set out to test whether the borders of the 11q13 amplicon are restricted to regions that enable DNA breakage and subsequent amplification. A high-resolution array of the 11q13 region was generated to study the structure of the 11q13 amplicon and analyzed 29 laryngeal and pharyngeal carcinomas and nine cell lines with 11q13 amplification. We found that boundaries of the commonly amplified region were restricted to four segments. Three boundaries coincided with a syntenic breakpoint. Such regions have been suggested to be putatively fragile. Sequence comparisons revealed that the amplicon was flanked by two large low copy repeats known as segmental duplications. These segmental duplications might be responsible for the typical structure and size of the 11q13 amplicon. We hypothesize that the selection for genes through amplification of the 11q13.3 region is determined by the ability to form DNA breaks within specific regions and, consequently, results in large amplicons containing multiple genes.
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Affiliation(s)
- Johan H Gibcus
- Department of Pathology, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands
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29
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Fridmanis D, Fredriksson R, Kapa I, Schiöth HB, Klovins J. Formation of new genes explains lower intron density in mammalian Rhodopsin G protein-coupled receptors. Mol Phylogenet Evol 2006; 43:864-80. [PMID: 17188520 DOI: 10.1016/j.ympev.2006.11.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 10/06/2006] [Accepted: 11/02/2006] [Indexed: 10/23/2022]
Abstract
Mammalian G protein-coupled receptor (GPCR) genes are characterised by a large proportion of intronless genes or a lower density of introns when compared with GPCRs of invertebrates. It is unclear which mechanisms have influenced intron density in this protein family, which is one of the largest in the mammalian genomes. We used a combination of Hidden Markov Models (HMM) and BLAST searches to establish the comprehensive repertoire of Rhodopsin GPCRs from seven species and performed overall alignments and phylogenetic analysis using the maximum parsimony method for over 1400 receptors in 12 subgroups. We identified 14 different Ancestral Receptor Groups (ARGs) that have members in both vertebrate and invertebrate species. We found that there exists a remarkable difference in the intron density among ancestral and new Rhodopsin GPCRs. The intron density among ARGs members was more than 3.5-fold higher than that within non-ARG members and more than 2-fold higher when considering only the 7TM region. This suggests that the new GPCR genes have been predominantly formed intronless while the ancestral receptors likely accumulated introns during their evolution. Many of the intron positions found in mammalian ARG receptor sequences were found to be present in orthologue invertebrate receptors suggesting that these intron positions are ancient. This analysis also revealed that one intron position is much more frequent than any other position and it is common for a number of phylogenetically different Rhodopsin GPCR groups. This intron position lies within a functionally important, conserved, DRY motif which may form a proto-splice site that could contribute to positional intron insertion. Moreover, we have found that other receptor motifs, similar to DRY, also contain introns between the second and third nucleotide of the arginine codon which also forms a proto-splice site. Our analysis presents compelling evidence that there was not a major loss of introns in mammalian GPCRs and formation of new GPCRs among mammals explains why these have fewer introns compared to invertebrate GPCRs. We also discuss and speculate about the possible role of different RNA- and DNA-based mechanisms of intron insertion and loss.
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Affiliation(s)
- Davids Fridmanis
- Biomedical Research and Study Centre, University of Latvia, Ratsupites 1, Riga, Latvia
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30
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Mehan MR, Almonte M, Slaten E, Freimer NB, Rao PN, Ophoff RA. Analysis of segmental duplications reveals a distinct pattern of continuation-of-synteny between human and mouse genomes. Hum Genet 2006; 121:93-100. [PMID: 17091282 DOI: 10.1007/s00439-006-0277-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Accepted: 10/05/2006] [Indexed: 11/25/2022]
Abstract
About 5% of the human genome consists of large-scale duplicated segments of almost identical sequences. Segmental duplications (SDs) have been proposed to be involved in non-allelic homologous recombination leading to recurrent genomic variation and disease. It has also been suggested that these SDs are associated with syntenic rearrangements that have shaped the human genome. We have analyzed 14 members of a single family of closely related SDs in the human genome, some of which are associated with common inversion polymorphisms at chromosomes 8p23 and 4p16. Comparative analysis with the mouse genome revealed syntenic inversions for these two human polymorphic loci. In addition, 12 of the 14 SDs, while absent in the mouse genome, occur at the breaks of synteny; suggesting a non-random involvement of these sequences in genome evolution. Furthermore, we observed a syntenic familial relationship between 8 and 12 breakpoint-loci, where broken synteny that ends at one family member resumes at another, even across different chromosomes. Subsequent genome-wide assessment revealed that this relationship, which we named continuation-of-synteny, is not limited to the 8p23 family and occurs 46 times in the human genome with high frequency at specific chromosomes. Our analysis supports a non-random breakage model of genomic evolution with an active involvement of segmental duplications for specific regions of the human genome.
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Affiliation(s)
- Michael R Mehan
- Center for Neurobehavioral Genetics, Neuropsychiatric Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
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31
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Aloni R, Olender T, Lancet D. Ancient genomic architecture for mammalian olfactory receptor clusters. Genome Biol 2006; 7:R88. [PMID: 17010214 PMCID: PMC1794568 DOI: 10.1186/gb-2006-7-10-r88] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Accepted: 10/01/2006] [Indexed: 01/14/2023] Open
Abstract
A new tool for genome-wide definition of genomic gene clusters conserved in multiple species was applied to olfactory receptors in five mammals, demonstrating that most mammalian olfactory receptor clusters have a common ancestry. Background Mammalian olfactory receptor (OR) genes reside in numerous genomic clusters of up to several dozen genes. Whole-genome sequence alignment nets of five mammals allow their comprehensive comparison, aimed at reconstructing the ancestral olfactory subgenome. Results We developed a new and general tool for genome-wide definition of genomic gene clusters conserved in multiple species. Syntenic orthologs, defined as gene pairs showing conservation of both genomic location and coding sequence, were subjected to a graph theory algorithm for discovering CLICs (clusters in conservation). When applied to ORs in five mammals, including the marsupial opossum, more than 90% of the OR genes were found within a framework of 48 multi-species CLICs, invoking a general conservation of gene order and composition. A detailed analysis of individual CLICs revealed multiple differences among species, interpretable through species-specific genomic rearrangements and reflecting complex mammalian evolutionary dynamics. One significant instance involves CLIC #1, which lacks a human member, implying the human-specific deletion of an OR cluster, whose mouse counterpart has been tentatively associated with isovaleric acid odorant detection. Conclusion The identified multi-species CLICs demonstrate that most of the mammalian OR clusters have a common ancestry, preceding the split between marsupials and placental mammals. However, only two of these CLICs were capable of incorporating chicken OR genes, parsimoniously implying that all other CLICs emerged subsequent to the avian-mammalian divergence.
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Affiliation(s)
- Ronny Aloni
- Department of Molecular Genetics and the Crown Human Genome Center, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tsviya Olender
- Department of Molecular Genetics and the Crown Human Genome Center, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Doron Lancet
- Department of Molecular Genetics and the Crown Human Genome Center, The Weizmann Institute of Science, Rehovot 76100, Israel
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32
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Feldmesser E, Olender T, Khen M, Yanai I, Ophir R, Lancet D. Widespread ectopic expression of olfactory receptor genes. BMC Genomics 2006; 7:121. [PMID: 16716209 PMCID: PMC1508154 DOI: 10.1186/1471-2164-7-121] [Citation(s) in RCA: 192] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Accepted: 05/22/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Olfactory receptors (ORs) are the largest gene family in the human genome. Although they are expected to be expressed specifically in olfactory tissues, some ectopic expression has been reported, with special emphasis on sperm and testis. The present study systematically explores the expression patterns of OR genes in a large number of tissues and assesses the potential functional implication of such ectopic expression. RESULTS We analyzed the expression of hundreds of human and mouse OR transcripts, via EST and microarray data, in several dozens of human and mouse tissues. Different tissues had specific, relatively small OR gene subsets which had particularly high expression levels. In testis, average expression was not particularly high, and very few highly expressed genes were found, none corresponding to ORs previously implicated in sperm chemotaxis. Higher expression levels were more common for genes with a non-OR genomic neighbor. Importantly, no correlation in expression levels was detected for human-mouse orthologous pairs. Also, no significant difference in expression levels was seen between intact and pseudogenized ORs, except for the pseudogenes of subfamily 7E which has undergone a human-specific expansion. CONCLUSION The OR superfamily as a whole, show widespread, locus-dependent and heterogeneous expression, in agreement with a neutral or near neutral evolutionary model for transcription control. These results cannot reject the possibility that small OR subsets might play functional roles in different tissues, however considerable care should be exerted when offering a functional interpretation for ectopic OR expression based only on transcription information.
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Affiliation(s)
- Ester Feldmesser
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tsviya Olender
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Miriam Khen
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Itai Yanai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
- Present address: Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Ron Ophir
- Department of Biological Services, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Doron Lancet
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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33
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Kouprina N, Pavlicek A, Noskov VN, Solomon G, Otstot J, Isaacs W, Carpten JD, Trent JM, Schleutker J, Barrett JC, Jurka J, Larionov V. Dynamic structure of the SPANX gene cluster mapped to the prostate cancer susceptibility locus HPCX at Xq27. Genome Res 2006; 15:1477-86. [PMID: 16251457 PMCID: PMC1310635 DOI: 10.1101/gr.4212705] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Genetic linkage studies indicate that germline variations in a gene or genes on chromosome Xq27-28 are implicated in prostate carcinogenesis. The linkage peak of prostate cancer overlies a region of approximately 750 kb containing five SPANX genes (SPANX-A1, -A2, -B, -C, and -D) encoding sperm proteins associated with the nucleus; their expression was also detected in a variety of cancers. SPANX genes are >95% identical and reside within large segmental duplications (SDs) with a high level of similarity, which confounds mutational analysis of this gene family by routine PCR methods. In this work, we applied transformation-associated recombination cloning (TAR) in yeast to characterize individual SPANX genes from prostate cancer patients showing linkage to Xq27-28 and unaffected controls. Analysis of genomic TAR clones revealed a dynamic nature of the replicated region of linkage. Both frequent gene deletion/duplication and homology-based sequence transfer events were identified within the region and were presumably caused by recombinational interactions between SDs harboring the SPANX genes. These interactions contribute to diversity of the SPANX coding regions in humans. We speculate that the predisposition to prostate cancer in X-linked families is an example of a genomic disease caused by a specific architecture of the SPANX gene cluster.
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Affiliation(s)
- Natalay Kouprina
- Laboratory of Biosystems and Cancer, National Cancer Institute, Bethesda, Maryland 20892, USA
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34
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Hoppe R, Lambert TD, Samollow PB, Breer H, Strotmann J. Evolution of the "OR37" subfamily of olfactory receptors: a cross-species comparison. J Mol Evol 2006; 62:460-72. [PMID: 16547640 DOI: 10.1007/s00239-005-0093-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Accepted: 11/17/2005] [Indexed: 01/09/2023]
Abstract
Genes encoding the olfactory receptors of the "OR37" subfamily of the mouse are characterized by special features including a clustered expression pattern, assembly in two distinct gene clusters, and highly conserved putative promoter motifs. Mining the rat and dog databases revealed that these two species possess highly conserved clusters of OR37 genes at two syntenic genomic loci. In a prototherian mammal, the platypus (Ornithorhynchus anatinus), none of the characteristic OR37 genes were found. Examination of a metatherian mammal, the gray short-tailed opossum (Monodelphis domestica) revealed seven canonical OR37 genes, all phylogenetically related to cluster II genes and also organized similar to cluster II of eutherian species. In addition, their 5' upstream regions comprised sequence motifs related to the putative regulatory sequences of cluster II genes. Typical cluster I OR37 genes were identified only in the eutherian mammals examined, including the evolutionary ancient anteater, wherein OR37 genes related to both clusters were present. Together, these results reveal novel information concerning the phylogenetic origin and important evolutionary steps of the mammalian-specific OR37 olfactory receptor family.
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Affiliation(s)
- Reiner Hoppe
- Institute of Physiology, University of Hohenheim, Garbenstrasse 30, 70593, Stuttgart, Germany
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35
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Chapman BA, Bowers JE, Feltus FA, Paterson AH. Buffering of crucial functions by paleologous duplicated genes may contribute cyclicality to angiosperm genome duplication. Proc Natl Acad Sci U S A 2006; 103:2730-5. [PMID: 16467140 PMCID: PMC1413778 DOI: 10.1073/pnas.0507782103] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genome duplication followed by massive gene loss has permanently shaped the genomes of many higher eukaryotes, particularly angiosperms. It has long been believed that a primary advantage of genome duplication is the opportunity for the evolution of genes with new functions by modification of duplicated genes. If so, then patterns of genetic diversity among strains within taxa might reveal footprints of selection that are consistent with this advantage. Contrary to classical predictions that duplicated genes may be relatively free to acquire unique functionality, we find among both Arabidopsis ecotypes and Oryza subspecies that SNPs encode less radical amino acid changes in genes for which there exists a duplicated copy at a "paleologous" locus than in "singleton" genes. Preferential retention of duplicated genes encoding long complex proteins and their unexpectedly slow divergence (perhaps because of homogenization) suggest that a primary advantage of retaining duplicated paleologs may be the buffering of crucial functions. Functional buffering and functional divergence may represent extremes in the spectrum of duplicated gene fates. Functional buffering may be especially important during "genomic turmoil" immediately after genome duplication but continues to act approximately 60 million years later, and its gradual deterioration may contribute cyclicality to genome duplication in some lineages.
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Affiliation(s)
- Brad A. Chapman
- *Plant Genome Mapping Laboratory and Departments of
- Plant Biology
| | | | | | - Andrew H. Paterson
- *Plant Genome Mapping Laboratory and Departments of
- Plant Biology
- Genetics, and
- Crop and Soil Science, University of Georgia, Athens, GA 30602
- To whom correspondence should be addressed at:
Plant Genome Mapping Laboratory, University of Georgia, 111 Riverbend Road, Athens, GA 30602. E-mail:
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36
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Yue Y, Haaf T. 7E olfactory receptor gene clusters and evolutionary chromosome rearrangements. Cytogenet Genome Res 2006; 112:6-10. [PMID: 16276084 DOI: 10.1159/000087507] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Accepted: 03/01/2005] [Indexed: 11/19/2022] Open
Abstract
Olfactory receptor (OR) genes of the 7E subfamily have been duplicated to multiple regions throughout the human genome. Segmental duplications containing 7E OR genes have been associated with both pathological and evolutionary chromosome rearrangements. Many of these breakpoint regions coincide with breaks of chromosomal synteny in the mouse, rat and/or chicken genomes. Collectively, these data suggest that 7E OR-containing regions represent hot spots of genomic instability.
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Affiliation(s)
- Y Yue
- Institute for Human Genetics, Mainz University School of Medicine, Mainz, Germany
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37
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Jackson MS, Oliver K, Loveland J, Humphray S, Dunham I, Rocchi M, Viggiano L, Park JP, Hurles ME, Santibanez-Koref M. Evidence for widespread reticulate evolution within human duplicons. Am J Hum Genet 2005; 77:824-40. [PMID: 16252241 PMCID: PMC1271390 DOI: 10.1086/497704] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Accepted: 08/25/2004] [Indexed: 11/04/2022] Open
Abstract
Approximately 5% of the human genome consists of segmental duplications that can cause genomic mutations and may play a role in gene innovation. Reticulate evolutionary processes, such as unequal crossing-over and gene conversion, are known to occur within specific duplicon families, but the broader contribution of these processes to the evolution of human duplications remains poorly characterized. Here, we use phylogenetic profiling to analyze multiple alignments of 24 human duplicon families that span >8 Mb of DNA. Our results indicate that none of them are evolving independently, with all alignments showing sharp discontinuities in phylogenetic signal consistent with reticulation. To analyze these results in more detail, we have developed a quartet method that estimates the relative contribution of nucleotide substitution and reticulate processes to sequence evolution. Our data indicate that most of the duplications show a highly significant excess of sites consistent with reticulate evolution, compared with the number expected by nucleotide substitution alone, with 15 of 30 alignments showing a >20-fold excess over that expected. Using permutation tests, we also show that at least 5% of the total sequence shares 100% sequence identity because of reticulation, a figure that includes 74 independent tracts of perfect identity >2 kb in length. Furthermore, analysis of a subset of alignments indicates that the density of reticulation events is as high as 1 every 4 kb. These results indicate that phylogenetic relationships within recently duplicated human DNA can be rapidly disrupted by reticulate evolution. This finding has important implications for efforts to finish the human genome sequence, complicates comparative sequence analysis of duplicon families, and could profoundly influence the tempo of gene-family evolution.
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Affiliation(s)
- Michael S Jackson
- Institute of Human Genetics, University of Newcastle upon Tyne, International Centre for Life, Newcastle upon Tyne, United Kingdom.
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38
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Zafra de la Rosa G, Venegas-Vega CA, Monroy N, Contreras-Bucio G, Friedrich U, Houman M, Saad A, Fernández P, Kofman-Alfaro S, Cervantes A. Trisomy 3q25.1-qter and monosomy 8p23.1-pter in a patient: cytogenetic and molecular analysis with delineation of the phenotype. Am J Med Genet A 2005; 136:259-64. [PMID: 15957183 DOI: 10.1002/ajmg.a.30802] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We describe a 4-year-old boy with partial 3q trisomy and distal 8p monosomy. The patient presented with mental retardation, dysmorphic face, congenital heart defect, brain and genital anomalies, and behavioral problems. The conventional cytogenetic analysis showed a 46,XY,add(8p) karyotype. Reverse painting and microsatellite analysis demonstrated a partial monosomy of 8p23.1 --> pter and a partial trisomy of 3q25.1 --> qter. The data suggest that the chromosomal rearrangement originated from a de novo translocation in a paternal germinal cell. The phenotype observed in our patient resulted from the combination of those defects described in the isolated dup(3q) and distal del(8p) syndromes.
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39
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Abstract
Current models for the evolution of new gene functions after gene duplication presume that the duplication events themselves have no effect on fitness. But those duplications that result in new gene functions are likely to be positively selected from their inception. The evolution of new function may start with the amplification of an existing gene with some level of preadaptation for that function, followed by a period of competitive evolution among the gene copies, resulting in the preservation of the most effective variant and the 'pseudogenization' and eventual loss of the rest.
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Affiliation(s)
- M Pilar Francino
- Evolutionary Genomics Department, DOE Joint Genome Institute and Genomics Division, Lawrence Berkeley National Laboratory, 2800 Mitchell Dr, Walnut Creek, California, USA.
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40
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Gilad Y, Man O, Glusman G. A comparison of the human and chimpanzee olfactory receptor gene repertoires. Genome Res 2005; 15:224-30. [PMID: 15687286 PMCID: PMC546523 DOI: 10.1101/gr.2846405] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Olfactory receptor (OR) genes constitute the basis of the sense of smell and are encoded by the largest mammalian gene superfamily, with >1000 members. In humans, but not in mice or dogs, the majority of OR genes have become pseudogenes, suggesting that OR genes in humans evolve under different selection pressures than in other mammals. To explore this further, we compare the OR gene repertoire of human with its closest living evolutionary relative, by taking advantage of the recently sequenced genome of the chimpanzee. In agreement with previous reports based on a small number of ORs, we find that humans have a significantly higher proportion of OR pseudogenes than chimpanzees. Moreover, we can reject the possibility that humans have been accumulating OR pseudogenes at a constant neutral rate since the divergence of human and chimpanzee. The comparison of the two repertoires reveals two chimpanzee-specific OR subfamily expansions and three expansions specific to humans. It also suggests that a subset of OR genes are under positive selection in either the human or the chimpanzee lineage. Thus, although overall there is relaxed constraint on human olfaction relative to chimpanzee, species-specific sensory requirements appear to have shaped the evolution of the functional OR gene repertoires in both species.
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Affiliation(s)
- Yoav Gilad
- Yale University School of Medicine, Department of Genetics, New Haven, Connecticut 06520, USA.
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Niimura Y, Nei M. Comparative evolutionary analysis of olfactory receptor gene clusters between humans and mice. Gene 2005; 346:13-21. [PMID: 15716120 DOI: 10.1016/j.gene.2004.09.025] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Revised: 09/17/2004] [Accepted: 09/28/2004] [Indexed: 11/23/2022]
Abstract
Olfactory receptor (OR) genes form the largest multigene family in mammalian genomes. Humans have approximately 800 OR genes, but >50% of them are pseudogenes. By contrast, mice have approximately 1400 OR genes and pseudogenes are approximately 25%. To understand the evolutionary processes that shaped the difference of OR gene families between humans and mice, we studied the genomic locations of all human and mouse OR genes and conducted a detailed phylogenetic analysis using functional genes and pseudogenes. We identified 40 phylogenetic clades with high bootstrap supports, most of which contain both human and mouse genes. Interestingly, a particular clade contains approximately 100 pseudogenes in humans, whereas the numbers of pseudogenes are <20 for most of the mouse clades. We also found that the organization of OR genomic clusters is well conserved between humans and mice in many chromosomal locations. Despite the difference in the numbers of genes, the numbers of large genomic clusters are nearly the same for humans and mice. These observations suggest that the greater OR gene repertoire in mice has been generated mainly by tandem gene duplication within each genomic cluster.
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Affiliation(s)
- Yoshihito Niimura
- Institute of Molecular Evolutionary Genetics and Department of Biology, Pennsylvania State University, 328 Mueller Laboratory, University Park, PA 16802, USA.
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Grimwood J, Gordon LA, Olsen A, Terry A, Schmutz J, Lamerdin J, Hellsten U, Goodstein D, Couronne O, Tran-Gyamfi M, Aerts A, Altherr M, Ashworth L, Bajorek E, Black S, Branscomb E, Caenepeel S, Carrano A, Caoile C, Chan YM, Christensen M, Cleland CA, Copeland A, Dalin E, Dehal P, Denys M, Detter JC, Escobar J, Flowers D, Fotopulos D, Garcia C, Georgescu AM, Glavina T, Gomez M, Gonzales E, Groza M, Hammon N, Hawkins T, Haydu L, Ho I, Huang W, Israni S, Jett J, Kadner K, Kimball H, Kobayashi A, Larionov V, Leem SH, Lopez F, Lou Y, Lowry S, Malfatti S, Martinez D, McCready P, Medina C, Morgan J, Nelson K, Nolan M, Ovcharenko I, Pitluck S, Pollard M, Popkie AP, Predki P, Quan G, Ramirez L, Rash S, Retterer J, Rodriguez A, Rogers S, Salamov A, Salazar A, She X, Smith D, Slezak T, Solovyev V, Thayer N, Tice H, Tsai M, Ustaszewska A, Vo N, Wagner M, Wheeler J, Wu K, Xie G, Yang J, Dubchak I, Furey TS, DeJong P, Dickson M, Gordon D, Eichler EE, Pennacchio LA, Richardson P, Stubbs L, Rokhsar DS, Myers RM, Rubin EM, Lucas SM. The DNA sequence and biology of human chromosome 19. Nature 2004; 428:529-35. [PMID: 15057824 DOI: 10.1038/nature02399] [Citation(s) in RCA: 231] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Accepted: 02/10/2004] [Indexed: 12/11/2022]
Abstract
Chromosome 19 has the highest gene density of all human chromosomes, more than double the genome-wide average. The large clustered gene families, corresponding high G + C content, CpG islands and density of repetitive DNA indicate a chromosome rich in biological and evolutionary significance. Here we describe 55.8 million base pairs of highly accurate finished sequence representing 99.9% of the euchromatin portion of the chromosome. Manual curation of gene loci reveals 1,461 protein-coding genes and 321 pseudogenes. Among these are genes directly implicated in mendelian disorders, including familial hypercholesterolaemia and insulin-resistant diabetes. Nearly one-quarter of these genes belong to tandemly arranged families, encompassing more than 25% of the chromosome. Comparative analyses show a fascinating picture of conservation and divergence, revealing large blocks of gene orthology with rodents, scattered regions with more recent gene family expansions and deletions, and segments of coding and non-coding conservation with the distant fish species Takifugu.
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Affiliation(s)
- Jane Grimwood
- Stanford Human Genome Center, Department of Genetics, Stanford University School of Medicine, 975 California Avenue, Palo Alto, California 94304, USA.
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Noonan JP, Grimwood J, Schmutz J, Dickson M, Myers RM. Gene conversion and the evolution of protocadherin gene cluster diversity. Genome Res 2004; 14:354-66. [PMID: 14993203 PMCID: PMC353213 DOI: 10.1101/gr.2133704] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The synaptic cell adhesion molecules encoded by the protocadherin gene cluster are hypothesized to provide a molecular code involved in the generation of synaptic complexity in the developing brain. Variation in copy number and sequence content of protocadherin cluster genes among vertebrate species could reflect adaptive differences in protocadherin function. We have completed an analysis of zebrafish protocadherin cluster genes. Zebrafish have two unlinked protocadherin clusters, DrPcdh1 and DrPcdh2. Like mammalian protocadherin clusters, DrPcdh1 has both alpha and gamma variable and constant region exons. A consensus protocadherin promoter motif sequence identified in mammals is also conserved in zebrafish. Few orthologous relationships, however, are apparent between zebrafish and mammalian protocadherin proteins. Here we show that protocadherin cluster genes in human, mouse, rat, and zebrafish are subject to striking gene conversion events. These events are restricted to regions of the coding sequence, particularly the coding sequences of ectodomain 6 and the cytoplasmic domain. Diversity among paralogs is restricted to particular ectodomains that are excluded from conversion events. Conversion events are also strongly correlated with an increase in third-position GC content. We propose that the combination of lineage-specific duplication, restricted gene conversion, and adaptive variation in diversified ectodomains drives vertebrate protocadherin cluster evolution.
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Affiliation(s)
- James P Noonan
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305-5120, USA
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Bailey JA, Baertsch R, Kent WJ, Haussler D, Eichler EE. Hotspots of mammalian chromosomal evolution. Genome Biol 2004; 5:R23. [PMID: 15059256 PMCID: PMC395782 DOI: 10.1186/gb-2004-5-4-r23] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2003] [Revised: 02/20/2004] [Accepted: 02/23/2004] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Chromosomal evolution is thought to occur through a random process of breakage and rearrangement that leads to karyotype differences and disruption of gene order. With the availability of both the human and mouse genomic sequences, detailed analysis of the sequence properties underlying these breakpoints is now possible. RESULTS We report an abundance of primate-specific segmental duplications at the breakpoints of syntenic blocks in the human genome. Using conservative criteria, we find that 25% (122/461) of all breakpoints contain > or = 10 kb of duplicated sequence. This association is highly significant (p < 0.0001) when compared to a simulated random-breakage model. The significance is robust under a variety of parameters, multiple sets of conserved synteny data, and for orthologous breakpoints between and within chromosomes. A comparison of mouse lineage-specific breakpoints since the divergence of rat and mouse showed a similar association with regions associated with segmental duplications in the primate genome. CONCLUSION These results indicate that segmental duplications are associated with syntenic rearrangements, even when pericentromeric and subtelomeric regions are excluded. However, segmental duplications are not necessarily the cause of the rearrangements. Rather, our analysis supports a nonrandom model of chromosomal evolution that implicates specific regions within the mammalian genome as having been predisposed to both recurrent small-scale duplication and large-scale evolutionary rearrangements.
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Affiliation(s)
- Jeffrey A Bailey
- Department of Genetics, Center for Computational Genomics, Case Western Reserve University School of Medicine and University Hospitals of Cleveland, Cleveland, OH 44106, USA
| | - Robert Baertsch
- Center for Biomolecular Science and Engineering, University of California, Santa Cruz, CA 95064, USA
| | - W James Kent
- Center for Biomolecular Science and Engineering, University of California, Santa Cruz, CA 95064, USA
| | - David Haussler
- Howard Hughes Medical Institute, 321 Baskin Engineering, University of California, Santa Cruz, CA 95064, USA
| | - Evan E Eichler
- Department of Genetics, Center for Computational Genomics, Case Western Reserve University School of Medicine and University Hospitals of Cleveland, Cleveland, OH 44106, USA
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Olender T, Fuchs T, Linhart C, Shamir R, Adams M, Kalush F, Khen M, Lancet D. The canine olfactory subgenome. Genomics 2004; 83:361-72. [PMID: 14962662 DOI: 10.1016/j.ygeno.2003.08.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2003] [Revised: 08/06/2003] [Accepted: 08/11/2003] [Indexed: 10/26/2022]
Abstract
We identified 971 olfactory receptor (OR) genes in the dog genome, estimated to constitute approximately 80% of the canine OR repertoire. This was achieved by directed genomic DNA cloning of olfactory sequence tags as well as by mining the Celera canine genome sequences. The dog OR subgenome is estimated to have 12% pseudogenes, suggesting a functional repertoire similar to that of mouse and considerably larger than for humans. No novel OR families were discovered, but as many as 34 gene subfamilies were unique to the dog. "Fish-like" Class I ancient ORs constituted 18% of the repertoire, significantly more than in human and mouse. A set of 122 dog-human-mouse ortholog triplets was identified, with a relatively high fraction of Class I ORs. The elucidation of a large portion of the canine olfactory receptor gene superfamily, with some dog-specific attributes, may help us understand the unique chemosensory capacities of this species.
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Affiliation(s)
- Tsviya Olender
- Department of Molecular Genetics and the Crown Human Genome Center, The Weizmann Institute of Science, Rehovot 76100, Israel
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Copley RR, Goodstadt L, Ponting C. Eukaryotic domain evolution inferred from genome comparisons. Curr Opin Genet Dev 2003; 13:623-8. [PMID: 14638325 DOI: 10.1016/j.gde.2003.10.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Comparative analyses of eukaryotic genomes are providing insights into the mode and tempo of domain family evolution. Gene duplication, the source of family expansion, far exceeds the rate of emergence of domains from non-coding sequence, and the rate of recruitment of domains into novel architectures. Domain families that appear to be restricted to certain lineages are likely to be the result of gene duplication, coupled with rapid sequence diversification. If such families are evidence of past adaptation, then their functions must relate to the underlying mechanism of selection: competition among organisms.
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Affiliation(s)
- Richard R Copley
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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