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Bonito M, D’Atanasio E, Ravasini F, Cariati S, Finocchio A, Novelletto A, Trombetta B, Cruciani F. New insights into the evolution of human Y chromosome palindromes through mutation and gene conversion. Hum Mol Genet 2021; 30:2272-2285. [PMID: 34244762 PMCID: PMC8600007 DOI: 10.1093/hmg/ddab189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 07/01/2021] [Accepted: 07/05/2021] [Indexed: 12/16/2022] Open
Abstract
About one-quarter of the euchromatic portion of the male-specific region of the human Y chromosome consists of large duplicated sequences that are organized in eight palindromes (termed P1-P8), which undergo arm-to arm gene conversion, a proposed mechanism for maintaining their sequence integrity. Although the relevance of gene conversion in the evolution of palindromic sequences has been profoundly recognized, the dynamic of this mechanism is still nuanced. To shed light into the evolution of these genomic elements, we performed a high-depth (50×) targeted next-generation sequencing of the palindrome P6 in 157 subjects belonging to the most divergent evolutionary lineages of the Y chromosome. We found 118 new paralogous sequence variants, which were placed into the context of a robust Y chromosome phylogeny based on 7240 SNPs of the X-degenerate region. We mapped along the phylogeny 80 gene conversion events that shaped the diversity of P6 arms during recent human history. In contrast to previous studies, we demonstrated that arm-to-arm gene conversion, which occurs at a rate of 6.01 × 10 -6 conversions/base/year, is not biased toward the retention of the ancestral state of sequences. We also found a significantly lower mutation rate of the arms (6.18 × 10-10 mutations/base/year) compared with the spacer (9.16 × 10-10 mutations/base/year), a finding that may explain the observed higher inter-species conservation of arms, without invoking any bias of conversion. Finally, by formally testing the mutation/conversion balance in P6, we found that the arms of this palindrome reached a steady-state equilibrium between mutation and gene conversion.
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Affiliation(s)
- Maria Bonito
- Department of Biology and Biotechnology ‘Charles Darwin’, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Rome 0185, Italy
| | - Eugenia D’Atanasio
- Institute of Molecular Biology and Pathology (IBPM), CNR, Rome 0185, Italy
| | - Francesco Ravasini
- Department of Biology and Biotechnology ‘Charles Darwin’, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Rome 0185, Italy
| | - Selene Cariati
- Department of Biology and Biotechnology ‘Charles Darwin’, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Rome 0185, Italy
| | - Andrea Finocchio
- Department of Biology, University of Rome Tor Vergata, Rome 0133, Italy
| | - Andrea Novelletto
- Department of Biology, University of Rome Tor Vergata, Rome 0133, Italy
| | - Beniamino Trombetta
- Department of Biology and Biotechnology ‘Charles Darwin’, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Rome 0185, Italy
| | - Fulvio Cruciani
- Department of Biology and Biotechnology ‘Charles Darwin’, Sapienza University of Rome, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Rome 0185, Italy
- Institute of Molecular Biology and Pathology (IBPM), CNR, Rome 0185, Italy
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2
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Improved Models of Coalescence Ages of Y-DNA Haplogroups. Genes (Basel) 2021; 12:genes12060862. [PMID: 34200049 PMCID: PMC8228294 DOI: 10.3390/genes12060862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/27/2021] [Accepted: 06/02/2021] [Indexed: 11/19/2022] Open
Abstract
Databases of commercial DNA-testing companies now contain more customers with sequenced DNA than any completed academic study, leading to growing interest from academic and forensic entities. An important result for both these entities and the test takers themselves is how closely two individuals are related in time, as calculated through one or more molecular clocks. For Y-DNA, existing interpretations of these clocks are insufficiently accurate to usefully measure relatedness in historic times. In this article, I update the methods used to calculate coalescence ages (times to most-recent common ancestor, or TMRCAs) using a new, probabilistic statistical model that includes Y-SNP, Y-STR and ancilliary historical data, and provide examples of its use.
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3
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Sahakyan H, Margaryan A, Saag L, Karmin M, Flores R, Haber M, Kushniarevich A, Khachatryan Z, Bahmanimehr A, Parik J, Karafet T, Yunusbayev B, Reisberg T, Solnik A, Metspalu E, Hovhannisyan A, Khusnutdinova EK, Behar DM, Metspalu M, Yepiskoposyan L, Rootsi S, Villems R. Origin and diffusion of human Y chromosome haplogroup J1-M267. Sci Rep 2021; 11:6659. [PMID: 33758277 PMCID: PMC7987999 DOI: 10.1038/s41598-021-85883-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 03/08/2021] [Indexed: 01/31/2023] Open
Abstract
Human Y chromosome haplogroup J1-M267 is a common male lineage in West Asia. One high-frequency region-encompassing the Arabian Peninsula, southern Mesopotamia, and the southern Levant-resides ~ 2000 km away from the other one found in the Caucasus. The region between them, although has a lower frequency, nevertheless demonstrates high genetic diversity. Studies associate this haplogroup with the spread of farming from the Fertile Crescent to Europe, the spread of mobile pastoralism in the desert regions of the Arabian Peninsula, the history of the Jews, and the spread of Islam. Here, we study past human male demography in West Asia with 172 high-coverage whole Y chromosome sequences and 889 genotyped samples of haplogroup J1-M267. We show that this haplogroup evolved ~ 20,000 years ago somewhere in northwestern Iran, the Caucasus, the Armenian Highland, and northern Mesopotamia. The major branch-J1a1a1-P58-evolved during the early Holocene ~ 9500 years ago somewhere in the Arabian Peninsula, the Levant, and southern Mesopotamia. Haplogroup J1-M267 expanded during the Chalcolithic, the Bronze Age, and the Iron Age. Most probably, the spread of Afro-Asiatic languages, the spread of mobile pastoralism in the arid zones, or both of these events together explain the distribution of haplogroup J1-M267 we see today in the southern regions of West Asia.
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Affiliation(s)
- Hovhannes Sahakyan
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia.
- Laboratory of Evolutionary Genomics, Institute of Molecular Biology of National Academy of Sciences of the Republic of Armenia, 0014, Yerevan, Armenia.
| | - Ashot Margaryan
- Laboratory of Evolutionary Genomics, Institute of Molecular Biology of National Academy of Sciences of the Republic of Armenia, 0014, Yerevan, Armenia
- Lundbeck Foundation, Department of Biology, GeoGenetics Centre, University of Copenhagen, 1350, Copenhagen, Denmark
| | - Lauri Saag
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
| | - Monika Karmin
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
- Statistics and Bioinformatics Group, Institute of Fundamental Sciences, Massey University, Palmerston North, Manawatu, 4442, New Zealand
| | - Rodrigo Flores
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
| | - Marc Haber
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Alena Kushniarevich
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
| | - Zaruhi Khachatryan
- Laboratory of Evolutionary Genomics, Institute of Molecular Biology of National Academy of Sciences of the Republic of Armenia, 0014, Yerevan, Armenia
| | - Ardeshir Bahmanimehr
- Laboratory of Evolutionary Genomics, Institute of Molecular Biology of National Academy of Sciences of the Republic of Armenia, 0014, Yerevan, Armenia
- Thalassemia and Haemophilia Genetic PND Research Center, Dastgheib Hospital, Shiraz University of Medical Sciences, 71456-83769, Shiraz, Iran
| | - Jüri Parik
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
- Department of Evolutionary Biology, Institute of Cell and Molecular Biology, University of Tartu, 51010, Tartu, Estonia
| | - Tatiana Karafet
- ARL Division of Biotechnology, University of Arizona, Tucson, AZ, 85721, USA
| | - Bayazit Yunusbayev
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
- Department of Genetics and Fundamental Medicine of Bashkir State University, Ufa, Bashkortostan, Russia, 450076
| | - Tuuli Reisberg
- Core Facility, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
| | - Anu Solnik
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
- Core Facility, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
| | - Ene Metspalu
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
| | - Anahit Hovhannisyan
- Laboratory of Evolutionary Genomics, Institute of Molecular Biology of National Academy of Sciences of the Republic of Armenia, 0014, Yerevan, Armenia
| | - Elza K Khusnutdinova
- Department of Genetics and Fundamental Medicine of Bashkir State University, Ufa, Bashkortostan, Russia, 450076
- Institute of Biochemistry and Genetics of Ufa Federal Research Center of the Russian Academy of Sciences, Ufa, 450054, Russia
| | - Doron M Behar
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
| | - Mait Metspalu
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
| | - Levon Yepiskoposyan
- Laboratory of Evolutionary Genomics, Institute of Molecular Biology of National Academy of Sciences of the Republic of Armenia, 0014, Yerevan, Armenia
| | - Siiri Rootsi
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
| | - Richard Villems
- Estonian Biocentre, Institute of Genomics, University of Tartu, 51010, Tartu, Estonia
- Department of Evolutionary Biology, Institute of Cell and Molecular Biology, University of Tartu, 51010, Tartu, Estonia
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Grugni V, Raveane A, Ongaro L, Battaglia V, Trombetta B, Colombo G, Capodiferro MR, Olivieri A, Achilli A, Perego UA, Motta J, Tribaldos M, Woodward SR, Ferretti L, Cruciani F, Torroni A, Semino O. Analysis of the human Y-chromosome haplogroup Q characterizes ancient population movements in Eurasia and the Americas. BMC Biol 2019; 17:3. [PMID: 30674303 PMCID: PMC6345020 DOI: 10.1186/s12915-018-0622-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 12/21/2018] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Recent genome studies of modern and ancient samples have proposed that Native Americans derive from a subset of the Eurasian gene pool carried to America by an ancestral Beringian population, from which two well-differentiated components originated and subsequently mixed in different proportion during their spread in the Americas. To assess the timing, places of origin and extent of admixture between these components, we performed an analysis of the Y-chromosome haplogroup Q, which is the only Pan-American haplogroup and accounts for virtually all Native American Y chromosomes in Mesoamerica and South America. RESULTS Our analyses of 1.5 Mb of 152 Y chromosomes, 34 re-sequenced in this work, support a "coastal and inland routes scenario" for the first entrance of modern humans in North America. We show a major phase of male population growth in the Americas after 15 thousand years ago (kya), followed by a period of constant population size from 8 to 3 kya, after which a secondary sign of growth was registered. The estimated dates of the first expansion in Mesoamerica and the Isthmo-Colombian Area, mainly revealed by haplogroup Q-Z780, suggest an entrance in South America prior to 15 kya. During the global constant population size phase, local South American hints of growth were registered by different Q-M848 sub-clades. These expansion events, which started during the Holocene with the improvement of climatic conditions, can be ascribed to multiple cultural changes rather than a steady population growth and a single cohesive culture diffusion as it occurred in Europe. CONCLUSIONS We established and dated a detailed haplogroup Q phylogeny that provides new insights into the geographic distribution of its Eurasian and American branches in modern and ancient samples.
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Affiliation(s)
- Viola Grugni
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy
| | - Alessandro Raveane
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy
| | - Linda Ongaro
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy.,Estonian Biocentre, Institute of Genomics, University of Tartu, Tartu, Estonia
| | - Vincenza Battaglia
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy
| | - Beniamino Trombetta
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza Università di Roma, Rome, Italy
| | - Giulia Colombo
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy
| | - Marco Rosario Capodiferro
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy
| | - Anna Olivieri
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy
| | - Alessandro Achilli
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy
| | - Ugo A Perego
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy
| | - Jorge Motta
- Secretaría Nacional de Ciencia, Tecnología e Innovación (SENACYT), Panama City, Panama
| | - Maribel Tribaldos
- Department of Health Technology Assessment and Economic Evaluation, Panama City, Panama
| | | | - Luca Ferretti
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy
| | - Fulvio Cruciani
- Dipartimento di Biologia e Biotecnologie "C. Darwin", Sapienza Università di Roma, Rome, Italy
| | - Antonio Torroni
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy
| | - Ornella Semino
- Dipartimento di Biologia e Biotecnologie "L. Spallanzani", Università di Pavia, Via Ferrata, 9, 27100, Pavia, Italy.
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5
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D’Atanasio E, Trombetta B, Bonito M, Finocchio A, Di Vito G, Seghizzi M, Romano R, Russo G, Paganotti GM, Watson E, Coppa A, Anagnostou P, Dugoujon JM, Moral P, Sellitto D, Novelletto A, Cruciani F. The peopling of the last Green Sahara revealed by high-coverage resequencing of trans-Saharan patrilineages. Genome Biol 2018; 19:20. [PMID: 29433568 PMCID: PMC5809971 DOI: 10.1186/s13059-018-1393-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 01/19/2018] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Little is known about the peopling of the Sahara during the Holocene climatic optimum, when the desert was replaced by a fertile environment. RESULTS In order to investigate the role of the last Green Sahara in the peopling of Africa, we deep-sequence the whole non-repetitive portion of the Y chromosome in 104 males selected as representative of haplogroups which are currently found to the north and to the south of the Sahara. We identify 5,966 mutations, from which we extract 142 informative markers then genotyped in about 8,000 subjects from 145 African, Eurasian and African American populations. We find that the coalescence age of the trans-Saharan haplogroups dates back to the last Green Sahara, while most northern African or sub-Saharan clades expanded locally in the subsequent arid phase. CONCLUSIONS Our findings suggest that the Green Sahara promoted human movements and demographic expansions, possibly linked to the adoption of pastoralism. Comparing our results with previously reported genome-wide data, we also find evidence for a sex-biased sub-Saharan contribution to northern Africans, suggesting that historical events such as the trans-Saharan slave trade mainly contributed to the mtDNA and autosomal gene pool, whereas the northern African paternal gene pool was mainly shaped by more ancient events.
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Affiliation(s)
- Eugenia D’Atanasio
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza Università di Roma, Rome, Italy
- Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza Università di Roma, Rome, Italy
| | - Beniamino Trombetta
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza Università di Roma, Rome, Italy
| | - Maria Bonito
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza Università di Roma, Rome, Italy
| | - Andrea Finocchio
- Dipartimento di Biologia, Università di Roma “Tor Vergata”, Rome, Italy
| | - Genny Di Vito
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza Università di Roma, Rome, Italy
| | - Mara Seghizzi
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza Università di Roma, Rome, Italy
| | - Rita Romano
- Dipartimento di Sanità Pubblica e Malattie Infettive, Sapienza Università di Roma, Rome, Italy
| | - Gianluca Russo
- Dipartimento di Sanità Pubblica e Malattie Infettive, Sapienza Università di Roma, Rome, Italy
| | - Giacomo Maria Paganotti
- Botswana-University of Pennsylvania Partnership, Gaborone, Botswana
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA
| | | | - Alfredo Coppa
- Dipartimento di Biologia Ambientale, Sapienza Università di Roma, Rome, Italy
| | - Paolo Anagnostou
- Dipartimento di Biologia Ambientale, Sapienza Università di Roma, Rome, Italy
- Istituto Italiano di Antropologia, Rome, Italy
| | - Jean-Michel Dugoujon
- Centre National de la Recherche Scientifique (CNRS), Université Toulouse-3–Paul-Sabatier, Toulouse, France
| | - Pedro Moral
- Department of Animal Biology-Anthropology, Biodiversity Research Institute, University of Barcelona, Barcelona, Spain
| | | | - Andrea Novelletto
- Dipartimento di Biologia, Università di Roma “Tor Vergata”, Rome, Italy
| | - Fulvio Cruciani
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza Università di Roma, Rome, Italy
- Istituto di Biologia e Patologia Molecolari, CNR, Rome, Italy
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6
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Trombetta B, D'Atanasio E, Cruciani F. Patterns of Inter-Chromosomal Gene Conversion on the Male-Specific Region of the Human Y Chromosome. Front Genet 2017; 8:54. [PMID: 28515739 PMCID: PMC5413550 DOI: 10.3389/fgene.2017.00054] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 04/18/2017] [Indexed: 12/31/2022] Open
Abstract
The male-specific region of the human Y chromosome (MSY) is characterized by the lack of meiotic recombination and it has long been considered an evolutionary independent region of the human genome. In recent years, however, the idea that human MSY did not have an independent evolutionary history begun to emerge with the discovery that inter-chromosomal gene conversion (ICGC) can modulate the genetic diversity of some portions of this genomic region. Despite the study of the dynamics of this molecular mechanism in humans is still in its infancy, some peculiar features and consequences of it can be summarized. The main effect of ICGC is to increase the allelic diversity of MSY by generating a significant excess of clustered single nucleotide polymorphisms (SNPs) (defined as groups of two or more SNPs occurring in close proximity and on the same branch of the Y phylogeny). On the human MSY, 13 inter-chromosomal gene conversion hotspots (GCHs) have been identified so far, involving donor sequences mainly from the X-chromosome and, to a lesser extent, from autosomes. Most of the GCHs are evolutionary conserved and overlap with regions involved in aberrant X–Y crossing-over. This review mainly focuses on the dynamics and the current knowledge concerning the recombinational landscape of the human MSY in the form of ICGC, on how this molecular mechanism may influence the evolution of the MSY, and on how it could affect the information enclosed within a genomic region which, until recently, appeared to be an evolutionary independent unit.
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Affiliation(s)
- Beniamino Trombetta
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di RomaRome, Italy
| | - Eugenia D'Atanasio
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di RomaRome, Italy
| | - Fulvio Cruciani
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di RomaRome, Italy.,Istituto di Biologia e Patologia Molecolari, Consiglio Nazionale delle Ricerche (CNR),Rome, Italy
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Toward a consensus on SNP and STR mutation rates on the human Y-chromosome. Hum Genet 2017; 136:575-590. [PMID: 28455625 DOI: 10.1007/s00439-017-1805-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/20/2017] [Indexed: 10/19/2022]
Abstract
The mutation rate on the Y-chromosome matters for estimating the time-to-the-most-recent-common-ancestor (TMRCA, i.e. haplogroup age) in population genetics, as well as for forensic, medical, and genealogical studies. Large-scale sequencing efforts have produced several independent estimates of Y-SNP mutation rates. Genealogical, or pedigree, rates tend to be slightly faster than evolutionary rates obtained from ancient DNA or calibrations using dated (pre)historical events. It is, therefore, suggested to report TMRCAs using an envelope defined by the average aDNA-based rate and the average pedigree-based rate. The current estimate of the "envelope rate" is 0.75-0.89 substitutions per billion base pairs per year. The available Y-SNP mutation rates can be applied to high-coverage data from the entire X-degenerate region, but other datasets may demand recalibrated rates. While a consensus on Y-SNP rates is approaching, the debate on Y-STR rates has continued for two decades, because multiple genealogical rates were consistent with each other but three times faster than the single evolutionary estimate. Applying Y-SNP and Y-STR rates to the same haplogroups recently helped to clarify the issue. Genealogical and evolutionary STR rates typically provide lower and upper bounds of the "true" (SNP-based) age. The genealogical rate often-but not always-works well for haplogroups less than 7000 years old. The evolutionary rate, although calibrated using recent events, inflates ages of young haplogroups and deflates the age of the entire Y-chromosomal tree, but often provides reasonable estimates for intermediate ages (old haplogroups). Future rate estimates and accumulating case studies should further clarify the Y-SNP rates.
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8
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Y chromosome palindromes and gene conversion. Hum Genet 2017; 136:605-619. [PMID: 28303348 DOI: 10.1007/s00439-017-1777-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 03/07/2017] [Indexed: 02/02/2023]
Abstract
The presence of large and near-identical inverted repeat sequences (called palindromes) is a common feature of the constitutively haploid sex chromosomes of different species. Despite the fact palindromes originated in a non-recombining context, they have evolved a strong recombinational activity in the form of abundant arm-to-arm gene conversion. Their independent appearance in different species suggests they can have a profound biological significance that has yet to be fully clarified. It has been theorized that natural selection may have favored palindromic organization of male-specific genes and that the establishment of intra-palindrome gene conversion has strong adaptive significance. Arm-to-arm gene conversion allows the efficient removal of deleterious mutations, increases the fixation rate of beneficial mutations and has played an important role in modulating the equilibrium between gene loss and acquisition during Y chromosome evolution. Additionally, a palindromic organization of duplicates could favor the formation of unusual chromatin structures and could optimize the use of gene conversion as a mechanism to maintain the structural integrity of male-specific genes. In this review, we describe the structural features of palindromes on mammalian sex chromosomes and summarize different hypotheses regarding palindrome evolution and the functional benefits of arm-to-arm gene conversion on the unique haploid portion of the nuclear genome.
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9
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Trombetta B, Fantini G, D'Atanasio E, Sellitto D, Cruciani F. Evidence of extensive non-allelic gene conversion among LTR elements in the human genome. Sci Rep 2016; 6:28710. [PMID: 27346230 PMCID: PMC4921805 DOI: 10.1038/srep28710] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/06/2016] [Indexed: 12/16/2022] Open
Abstract
Long Terminal Repeats (LTRs) are nearly identical DNA sequences found at either end of Human Endogenous Retroviruses (HERVs). The high sequence similarity that exists among different LTRs suggests they could be substrate of ectopic gene conversion events. To understand the extent to which gene conversion occurs and to gain new insights into the evolutionary history of these elements in humans, we performed an intra-species phylogenetic study of 52 LTRs on different unrelated Y chromosomes. From this analysis, we obtained direct evidence that demonstrates the occurrence of ectopic gene conversion in several LTRs, with donor sequences located on both sex chromosomes and autosomes. We also found that some of these elements are characterized by an extremely high density of polymorphisms, showing one of the highest nucleotide diversities in the human genome, as well as a complex patchwork of sequences derived from different LTRs. Finally, we highlighted the limits of current short-read NGS studies in the analysis of genetic diversity of the LTRs in the human genome. In conclusion, our comparative re-sequencing analysis revealed that ectopic gene conversion is a common event in the evolution of LTR elements, suggesting complex genetic links among LTRs from different chromosomes.
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Affiliation(s)
- Beniamino Trombetta
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, Rome, Italy
| | - Gloria Fantini
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, Rome, Italy
| | - Eugenia D'Atanasio
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, Rome, Italy
| | | | - Fulvio Cruciani
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, Rome, Italy.,Istituto di Biologia e Patologia Molecolari, CNR, Rome, Italy.,Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza Università di Roma, Rome, Italy
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