1
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Hanke DM, Wang Y, Dagan T. Pseudogenes in plasmid genomes reveal past transitions in plasmid mobility. Nucleic Acids Res 2024; 52:7049-7062. [PMID: 38808675 PMCID: PMC11229322 DOI: 10.1093/nar/gkae430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 04/23/2024] [Accepted: 05/08/2024] [Indexed: 05/30/2024] Open
Abstract
Evidence for gene non-functionalization due to mutational processes is found in genomes in the form of pseudogenes. Pseudogenes are known to be rare in prokaryote chromosomes, with the exception of lineages that underwent an extreme genome reduction (e.g. obligatory symbionts). Much less is known about the frequency of pseudogenes in prokaryotic plasmids; those are genetic elements that can transfer between cells and may encode beneficial traits for their host. Non-functionalization of plasmid-encoded genes may alter the plasmid characteristics, e.g. mobility, or their effect on the host. Analyzing 10 832 prokaryotic genomes, we find that plasmid genomes are characterized by threefold-higher pseudogene density compared to chromosomes. The majority of plasmid pseudogenes correspond to deteriorated transposable elements. A detailed analysis of enterobacterial plasmids furthermore reveals frequent gene non-functionalization events associated with the loss of plasmid self-transmissibility. Reconstructing the evolution of closely related plasmids reveals that non-functionalization of the conjugation machinery led to the emergence of non-mobilizable plasmid types. Examples are virulence plasmids in Escherichia and Salmonella. Our study highlights non-functionalization of core plasmid mobility functions as one route for the evolution of domesticated plasmids. Pseudogenes in plasmids supply insights into past transitions in plasmid mobility that are akin to transitions in bacterial lifestyle.
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Affiliation(s)
- Dustin M Hanke
- Institute of General Microbiology, Kiel University, Kiel, Germany
| | - Yiqing Wang
- Institute of General Microbiology, Kiel University, Kiel, Germany
| | - Tal Dagan
- Institute of General Microbiology, Kiel University, Kiel, Germany
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2
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Sharif J, Koseki H, Parrish NF. Bridging multiple dimensions: roles of transposable elements in higher-order genome regulation. Curr Opin Genet Dev 2023; 80:102035. [PMID: 37028152 DOI: 10.1016/j.gde.2023.102035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/01/2023] [Accepted: 03/05/2023] [Indexed: 04/09/2023]
Abstract
Transposable elements (TEs) such as endogenous retroviruses (ERVs), long interspersed nuclear elements (LINEs), and short interspersed nuclear elements (SINEs) occupy nearly half of typical mammalian genomes. Previous studies show that these parasitic elements, especially LINEs and ERVs, provide important activities promoting host germ cell and placental development, preimplantation embryogenesis, and maintenance of pluripotent stem cells. Despite being the most numerically abundant type of TEs in the genome, the consequences of SINEs on host genome regulation are less well characterized than those of ERVs and LINEs. Interestingly, recent findings reveal that SINEs recruit the key architectural protein CTCF (CCCTC-binding factor), indicating a role of these elements for 3D genome regulation. Higher-order nuclear structures are linked with important cellular functions such as gene regulation and DNA replication. SINEs and other TEs, therefore, may mediate distinct physiological processes with benefits to the host by modulating the 3D genome.
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Affiliation(s)
- Jafar Sharif
- Laboratory of Developmental Genetics, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
| | - Haruhiko Koseki
- Laboratory of Developmental Genetics, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan; Department of Cellular and Molecular Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
| | - Nicholas F Parrish
- Genome Immunobiology RIKEN Hakubi Research Team, RIKEN Center for Integrative Medical Sciences and RIKEN Cluster for Pioneering Research, Yokohama, Japan.
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3
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Sievers A, Sauer L, Bisch M, Sprengel J, Hausmann M, Hildenbrand G. Moderation of Structural DNA Properties by Coupled Dinucleotide Contents in Eukaryotes. Genes (Basel) 2023; 14:genes14030755. [PMID: 36981025 PMCID: PMC10048725 DOI: 10.3390/genes14030755] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/16/2023] [Accepted: 03/18/2023] [Indexed: 03/30/2023] Open
Abstract
Dinucleotides are known as determinants for various structural and physiochemical properties of DNA and for binding affinities of proteins to DNA. These properties (e.g., stiffness) and bound proteins (e.g., transcription factors) are known to influence important biological functions, such as transcription regulation and 3D chromatin organization. Accordingly, the question arises of how the considerable variations in dinucleotide contents of eukaryotic chromosomes could still provide consistent DNA properties resulting in similar functions and 3D conformations. In this work, we investigate the hypothesis that coupled dinucleotide contents influence DNA properties in opposite directions to moderate each other's influences. Analyzing all 2478 chromosomes of 155 eukaryotic species, considering bias from coding sequences and enhancers, we found sets of correlated and anti-correlated dinucleotide contents. Using computational models, we estimated changes of DNA properties resulting from this coupling. We found that especially pure A/T dinucleotides (AA, TT, AT, TA), known to influence histone positioning and AC/GT contents, are relevant moderators and that, e.g., the Roll property, which is known to influence histone affinity of DNA, is preferably moderated. We conclude that dinucleotide contents might indirectly influence transcription and chromatin 3D conformation, via regulation of histone occupancy and/or other mechanisms.
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Affiliation(s)
- Aaron Sievers
- Kirchhoff Institute for Physics, Heidelberg University, INF 227, 69117 Heidelberg, Germany
- Institute for Human Genetics, University Hospital Heidelberg, INF 366, 69117 Heidelberg, Germany
| | - Liane Sauer
- Kirchhoff Institute for Physics, Heidelberg University, INF 227, 69117 Heidelberg, Germany
- Institute for Human Genetics, University Hospital Heidelberg, INF 366, 69117 Heidelberg, Germany
| | - Marc Bisch
- Kirchhoff Institute for Physics, Heidelberg University, INF 227, 69117 Heidelberg, Germany
| | - Jan Sprengel
- Kirchhoff Institute for Physics, Heidelberg University, INF 227, 69117 Heidelberg, Germany
| | - Michael Hausmann
- Kirchhoff Institute for Physics, Heidelberg University, INF 227, 69117 Heidelberg, Germany
| | - Georg Hildenbrand
- Kirchhoff Institute for Physics, Heidelberg University, INF 227, 69117 Heidelberg, Germany
- Faculty of Engeneering, University of Applied Science Aschaffenburg, Würzburger Str. 45, 63743 Aschaffenburg, Germany
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4
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Chakravorty N. Non-coding RNAs: the silent regulators of health and diseases. Mol Biol Rep 2022; 49:6971-6973. [PMID: 35467178 PMCID: PMC9036841 DOI: 10.1007/s11033-022-07464-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/07/2022] [Indexed: 11/28/2022]
Abstract
Non-coding RNAs (ncRNAs) like miRNAs, siRNA, lncRNAs, circRNAs, piRNAs, snoRNAs, snRNAs etc. form a collective group of RNAs that is instrumental to the various functions of the genome. With the advent of cutting-edge molecular biology tools and techniques, scientists have unearthed several mechanisms through which these ncRNAs act. Although our understanding may still be limited, yet scientists have been able to establish ncRNAs as major regulators of genetic inter-plays that dictate various pathophysiological conditions. This special issue of Molecular Biology Reports features a collection of research and review articles on ncRNAs and their involvement in different pathophysiological conditions that include different types of cancers. It is expected that this special issue will motivate researchers in the field to delve deeper into the world of ncRNAs and attempt to develop new diagnostic and therapeutic interventions for challenging clinical conditions.
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Affiliation(s)
- Nishant Chakravorty
- School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Paschim Medinipur, Kharagpur, 721302, India.
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5
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Santander MD, Maronna MM, Ryan JF, Andrade SCS. The state of Medusozoa genomics: current evidence and future challenges. Gigascience 2022; 11:6586816. [PMID: 35579552 PMCID: PMC9112765 DOI: 10.1093/gigascience/giac036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/18/2022] [Accepted: 03/15/2022] [Indexed: 12/13/2022] Open
Abstract
Medusozoa is a widely distributed ancient lineage that harbors one-third of Cnidaria diversity divided into 4 classes. This clade is characterized by the succession of stages and modes of reproduction during metagenic lifecycles, and includes some of the most plastic body plans and life cycles among animals. The characterization of traditional genomic features, such as chromosome numbers and genome sizes, was rather overlooked in Medusozoa and many evolutionary questions still remain unanswered. Modern genomic DNA sequencing in this group started in 2010 with the publication of the Hydra vulgaris genome and has experienced an exponential increase in the past 3 years. Therefore, an update of the state of Medusozoa genomics is warranted. We reviewed different sources of evidence, including cytogenetic records and high-throughput sequencing projects. We focused on 4 main topics that would be relevant for the broad Cnidaria research community: (i) taxonomic coverage of genomic information; (ii) continuity, quality, and completeness of high-throughput sequencing datasets; (iii) overview of the Medusozoa specific research questions approached with genomics; and (iv) the accessibility of data and metadata. We highlight a lack of standardization in genomic projects and their reports, and reinforce a series of recommendations to enhance future collaborative research.
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Affiliation(s)
- Mylena D Santander
- Correspondence address. Mylena D. Santander, Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade São Paulo, 277 Rua do Matão, Cidade Universitária, São Paulo 05508-090, Brazil. E-mail:
| | - Maximiliano M Maronna
- Correspondence address. Maximiliano M. Maronna, Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, 101 Rua do Matão Cidade Universitária, São Paulo 05508-090, Brazil. E-mail:
| | - Joseph F Ryan
- Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd, St. Augustine, FL 32080, USA,Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL 32611, USA
| | - Sónia C S Andrade
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade São Paulo, 277 Rua do Matão, Cidade Universitária, São Paulo 05508-090, Brazil
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Affiliation(s)
| | - Francisco J. Ruiz-Ruano
- Department of Organismal Biology – Systematic Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
- School of Biological Sciences, Norwich Research Park University of East Anglia, Norwich, UK
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7
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Taming, Domestication and Exaptation: Trajectories of Transposable Elements in Genomes. Cells 2021; 10:cells10123590. [PMID: 34944100 PMCID: PMC8700633 DOI: 10.3390/cells10123590] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/30/2021] [Accepted: 12/06/2021] [Indexed: 02/06/2023] Open
Abstract
During evolution, several types of sequences pass through genomes. Along with mutations and internal genetic tinkering, they are a useful source of genetic variability for adaptation and evolution. Most of these sequences are acquired by horizontal transfers (HT), but some of them may come from the genomes themselves. If they are not lost or eliminated quickly, they can be tamed, domesticated, or even exapted. Each of these processes results from a series of events, depending on the interactions between these sequences and the host genomes, but also on environmental constraints, through their impact on individuals or population fitness. After a brief reminder of the characteristics of each of these states (taming, domestication, exaptation), the evolutionary trajectories of these new or acquired sequences will be presented and discussed, emphasizing that they are not totally independent insofar as the first can constitute a step towards the second, and the second is another step towards the third.
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8
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Robin AN, Denton KK, Horna Lowell ES, Dulay T, Ebrahimi S, Johnson GC, Mai D, O’Fallon S, Philson CS, Speck HP, Zhang XP, Nonacs P. Major Evolutionary Transitions and the Roles of Facilitation and Information in Ecosystem Transformations. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.711556] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
A small number of extraordinary “Major Evolutionary Transitions” (METs) have attracted attention among biologists. They comprise novel forms of individuality and information, and are defined in relation to organismal complexity, irrespective of broader ecosystem-level effects. This divorce between evolutionary and ecological consequences qualifies unicellular eukaryotes, for example, as a MET although they alone failed to significantly alter ecosystems. Additionally, this definition excludes revolutionary innovations not fitting into either MET type (e.g., photosynthesis). We recombine evolution with ecology to explore how and why entire ecosystems were newly created or radically altered – as Major System Transitions (MSTs). In doing so, we highlight important morphological adaptations that spread through populations because of their immediate, direct-fitness advantages for individuals. These are Major Competitive Transitions, or MCTs. We argue that often multiple METs and MCTs must be present to produce MSTs. For example, sexually-reproducing, multicellular eukaryotes (METs) with anisogamy and exoskeletons (MCTs) significantly altered ecosystems during the Cambrian. Therefore, we introduce the concepts of Facilitating Evolutionary Transitions (FETs) and Catalysts as key events or agents that are insufficient themselves to set a MST into motion, but are essential parts of synergies that do. We further elucidate the role of information in MSTs as transitions across five levels: (I) Encoded; (II) Epigenomic; (III) Learned; (IV) Inscribed; and (V) Dark Information. The latter is ‘authored’ by abiotic entities rather than biological organisms. Level IV has arguably allowed humans to produce a MST, and V perhaps makes us a FET for a future transition that melds biotic and abiotic life into one entity. Understanding the interactive processes involved in past major transitions will illuminate both current events and the surprising possibilities that abiotically-created information may produce.
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9
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Garrido-Ramos MA. The Genomics of Plant Satellite DNA. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2021; 60:103-143. [PMID: 34386874 DOI: 10.1007/978-3-030-74889-0_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The twenty-first century began with a certain indifference to the research of satellite DNA (satDNA). Neither genome sequencing projects were able to accurately encompass the study of satDNA nor classic methodologies were able to go further in undertaking a better comprehensive study of the whole set of satDNA sequences of a genome. Nonetheless, knowledge of satDNA has progressively advanced during this century with the advent of new analytical techniques. The enormous advantages that genome-wide approaches have brought to its analysis have now stimulated a renewed interest in the study of satDNA. At this point, we can look back and try to assess more accurately many of the key questions that were left unsolved in the past about this enigmatic and important component of the genome. I review here the understanding gathered on plant satDNAs over the last few decades with an eye on the near future.
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10
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Brunet TDP, Doolittle WF, Bielawski JP. The role of purifying selection in the origin and maintenance of complex function. STUDIES IN HISTORY AND PHILOSOPHY OF SCIENCE 2021; 87:125-135. [PMID: 34111815 DOI: 10.1016/j.shpsa.2021.03.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 03/18/2021] [Indexed: 06/12/2023]
Abstract
Fitness contribution alone should not be the criterion of 'function' in molecular biology and genomics. Disagreement over the use of 'function' in molecular biology and genomics is still with us, almost eight years after publicity surrounding the Encyclopedia of DNA Elements project claimed that 80.4% of the human genome comprises "functional elements". Recent approaches attempt to resolve or reformulate this debate by redefining genomic 'function' in terms of current fitness contribution. In its favour, this redefinition for the genomic context is in apparent conformity with predominant experimental practices, especially in biomedical research, and with ascription of function by selective maintenance. We argue against approaches of this kind, however, on the grounds that they could be seen as non-Darwinian, and fail to properly account for the diversity of non-adaptive processes involved in the origin and maintenance of genomic complexity. We examine cases of molecular and organismal complexity that arise neutrally, showing how purifying selection maintains non-adaptive genomic complexity. Rather than lumping different sorts of genomic complexity together by defining 'function' as fitness contribution, we argue that it is best to separate the heterogeneous contributions of preaptation, exaptation and adaptation to the historical processes of origin and maintenance for complex features.
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Affiliation(s)
- Tyler D P Brunet
- Department of the History and Philosophy of Science, University of Cambridge, United Kingdom.
| | - W Ford Doolittle
- Department of Biochemistry and Molecular Biology, Dalhousie University, Canada
| | - Joseph P Bielawski
- Departments of Biology and Mathematics and Statistics, Dalhousie University, Canada
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11
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Song B, Chen K, Tang Y, Wei Z, Su J, de Magalhães JP, Rigden DJ, Meng J. ConsRM: collection and large-scale prediction of the evolutionarily conserved RNA methylation sites, with implications for the functional epitranscriptome. Brief Bioinform 2021; 22:6276017. [PMID: 33993206 DOI: 10.1093/bib/bbab088] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/04/2021] [Accepted: 02/24/2021] [Indexed: 12/15/2022] Open
Abstract
Motivation N6-methyladenosine (m6A) is the most prevalent RNA modification on mRNAs and lncRNAs. Evidence increasingly demonstrates its crucial importance in essential molecular mechanisms and various diseases. With recent advances in sequencing techniques, tens of thousands of m6A sites are identified in a typical high-throughput experiment, posing a key challenge to distinguish the functional m6A sites from the remaining 'passenger' (or 'silent') sites. Results: We performed a comparative conservation analysis of the human and mouse m6A epitranscriptomes at single site resolution. A novel scoring framework, ConsRM, was devised to quantitatively measure the degree of conservation of individual m6A sites. ConsRM integrates multiple information sources and a positive-unlabeled learning framework, which integrated genomic and sequence features to trace subtle hints of epitranscriptome layer conservation. With a series validation experiments in mouse, fly and zebrafish, we showed that ConsRM outperformed well-adopted conservation scores (phastCons and phyloP) in distinguishing the conserved and unconserved m6A sites. Additionally, the m6A sites with a higher ConsRM score are more likely to be functionally important. An online database was developed containing the conservation metrics of 177 998 distinct human m6A sites to support conservation analysis and functional prioritization of individual m6A sites. And it is freely accessible at: https://www.xjtlu.edu.cn/biologicalsciences/con.
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Affiliation(s)
- Bowen Song
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L7 8TX, Liverpool, United Kingdom
| | - Kunqi Chen
- Key Laboratory of Ministry of Education of Gastrointestinal Cancer, School of Basic Medical Science, Fujian Medical University, Fuzhou, China
| | - Yujiao Tang
- Xi'an Jiaotong-Liverpool University, L7 8TX, Liverpool, United Kingdom
| | - Zhen Wei
- Department of Biological Science, Xi'an Jiaotong-Liverpool University, L7 8TX, Liverpool, United Kingdom
| | - Jionglong Su
- Department of Mathematical Sciences, Xi'an Jiaotong-Liverpool University, L7 8TX, Liverpool, United Kingdom
| | - João Pedro de Magalhães
- Institute of Ageing & Chronic Disease, University of Liverpool, L7 8TX, Liverpool, United Kingdom
| | - Daniel J Rigden
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, L7 8TX, Liverpool, United Kingdom
| | - Jia Meng
- Department of Biological Sciences, Xi'an Jiaotong-Liverpool University, L7 8TX, Liverpool, United Kingdom
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12
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Plant Mitochondria are a Riddle Wrapped in a Mystery Inside an Enigma. J Mol Evol 2021; 89:151-156. [PMID: 33486550 DOI: 10.1007/s00239-020-09980-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 12/03/2020] [Indexed: 12/23/2022]
Abstract
A fundamental paradox motivates the study of plant mitochondrial genomics: the mutation rate is very low (lower than in the nucleus) but the rearrangement rate is high. A landmark paper published in Journal of Molecular Evolution in 1988 established these facts and revealed the paradox. Jeffrey Palmer and Laura Herbon did a prodigious amount of work in the pre-genome sequencing era to identify both the high frequency of rearrangements between closely related species, and the low frequency of mutations, observations that have now been confirmed many times by sequencing. This paper was also the first to use molecular data on rearrangements as a phylogenetic trait to build a parsimonious tree. The work was a technical tour-de-force, its findings are still at the heart of plant mitochondrial genomics, and the underlying molecular mechanisms that produce this paradox are still not completely understood.
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13
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Ahmad SF, Singchat W, Jehangir M, Suntronpong A, Panthum T, Malaivijitnond S, Srikulnath K. Dark Matter of Primate Genomes: Satellite DNA Repeats and Their Evolutionary Dynamics. Cells 2020; 9:E2714. [PMID: 33352976 PMCID: PMC7767330 DOI: 10.3390/cells9122714] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 12/12/2022] Open
Abstract
A substantial portion of the primate genome is composed of non-coding regions, so-called "dark matter", which includes an abundance of tandemly repeated sequences called satellite DNA. Collectively known as the satellitome, this genomic component offers exciting evolutionary insights into aspects of primate genome biology that raise new questions and challenge existing paradigms. A complete human reference genome was recently reported with telomere-to-telomere human X chromosome assembly that resolved hundreds of dark regions, encompassing a 3.1 Mb centromeric satellite array that had not been identified previously. With the recent exponential increase in the availability of primate genomes, and the development of modern genomic and bioinformatics tools, extensive growth in our knowledge concerning the structure, function, and evolution of satellite elements is expected. The current state of knowledge on this topic is summarized, highlighting various types of primate-specific satellite repeats to compare their proportions across diverse lineages. Inter- and intraspecific variation of satellite repeats in the primate genome are reviewed. The functional significance of these sequences is discussed by describing how the transcriptional activity of satellite repeats can affect gene expression during different cellular processes. Sex-linked satellites are outlined, together with their respective genomic organization. Mechanisms are proposed whereby satellite repeats might have emerged as novel sequences during different evolutionary phases. Finally, the main challenges that hinder the detection of satellite DNA are outlined and an overview of the latest methodologies to address technological limitations is presented.
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Affiliation(s)
- Syed Farhan Ahmad
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand
| | - Worapong Singchat
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand
| | - Maryam Jehangir
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Department of Structural and Functional Biology, Institute of Bioscience at Botucatu, São Paulo State University (UNESP), Botucatu, São Paulo 18618-689, Brazil
| | - Aorarat Suntronpong
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand
| | - Thitipong Panthum
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand
| | - Suchinda Malaivijitnond
- National Primate Research Center of Thailand, Chulalongkorn University, Saraburi 18110, Thailand;
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Kornsorn Srikulnath
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand
- National Primate Research Center of Thailand, Chulalongkorn University, Saraburi 18110, Thailand;
- Center of Excellence on Agricultural Biotechnology (AG-BIO/PERDO-CHE), Bangkok 10900, Thailand
- Omics Center for Agriculture, Bioresources, Food and Health, Kasetsart University (OmiKU), Bangkok 10900, Thailand
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14
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Palazzo AF, Koonin EV. Functional Long Non-coding RNAs Evolve from Junk Transcripts. Cell 2020; 183:1151-1161. [PMID: 33068526 DOI: 10.1016/j.cell.2020.09.047] [Citation(s) in RCA: 128] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/20/2020] [Accepted: 09/17/2020] [Indexed: 12/30/2022]
Abstract
Transcriptome studies reveal pervasive transcription of complex genomes, such as those of mammals. Despite popular arguments for functionality of most, if not all, of these transcripts, genome-wide analysis of selective constraints indicates that most of the produced RNA are junk. However, junk is not garbage. On the contrary, junk transcripts provide the raw material for the evolution of diverse long non-coding (lnc) RNAs by non-adaptive mechanisms, such as constructive neutral evolution. The generation of many novel functional entities, such as lncRNAs, that fuels organismal complexity does not seem to be driven by strong positive selection. Rather, the weak selection regime that dominates the evolution of most multicellular eukaryotes provides ample material for functional innovation with relatively little adaptation involved.
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Affiliation(s)
- Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada.
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
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15
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Blommaert J. Genome size evolution: towards new model systems for old questions. Proc Biol Sci 2020; 287:20201441. [PMID: 32842932 PMCID: PMC7482279 DOI: 10.1098/rspb.2020.1441] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 07/29/2020] [Indexed: 12/20/2022] Open
Abstract
Genome size (GS) variation is a fundamental biological characteristic; however, its evolutionary causes and consequences are the topic of ongoing debate. Whether GS is a neutral trait or one subject to selective pressures, and how strong these selective pressures are, may remain open questions. Fundamentally, the genomic sequences responsible for this variation directly impact the potential evolutionary outcomes and, equally, are the targets of different evolutionary pressures. For example, duplications and deletions of genic regions (large or small) can have immediate and drastic phenotypic effects, while an expansion or contraction of non-coding DNA is less likely to cause catastrophic phenotypic effects. However, in the long term, the accumulation or deletion of ncDNA is likely to have larger effects. Modern sequencing technologies are allowing for the dissection of these proximate causes, but a combination of these new technologies with more traditional evolutionary experiments and approaches could revolutionize this debate and potentially resolve many of these arguments. Here, I discuss an ambitious way forward for GS research, putting it in context of historical debates, theories and sometimes contradictory evidence, and highlighting the promise of combining new sequencing technologies and analytical developments with more traditional experimental evolution approaches.
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Affiliation(s)
- Julie Blommaert
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
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16
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Ardern Z, Neuhaus K, Scherer S. Are Antisense Proteins in Prokaryotes Functional? Front Mol Biosci 2020; 7:187. [PMID: 32923454 PMCID: PMC7457138 DOI: 10.3389/fmolb.2020.00187] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 07/16/2020] [Indexed: 12/16/2022] Open
Abstract
Many prokaryotic RNAs are transcribed from loci outside of annotated protein coding genes. Across bacterial species hundreds of short open reading frames antisense to annotated genes show evidence of both transcription and translation, for instance in ribosome profiling data. Determining the functional fraction of these protein products awaits further research, including insights from studies of molecular interactions and detailed evolutionary analysis. There are multiple lines of evidence, however, that many of these newly discovered proteins are of use to the organism. Condition-specific phenotypes have been characterized for a few. These proteins should be added to genome annotations, and the methods for predicting them standardized. Evolutionary analysis of these typically young sequences also may provide important insights into gene evolution. This research should be prioritized for its exciting potential to uncover large numbers of novel proteins with extremely diverse potential practical uses, including applications in synthetic biology and responding to pathogens.
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Affiliation(s)
- Zachary Ardern
- Chair for Microbial Ecology, Technical University of Munich, Munich, Germany
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17
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Brzović Z, Šustar P. Postgenomics function monism. STUDIES IN HISTORY AND PHILOSOPHY OF BIOLOGICAL AND BIOMEDICAL SCIENCES 2020; 80:101243. [PMID: 31924514 DOI: 10.1016/j.shpsc.2019.101243] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 10/08/2019] [Accepted: 12/27/2019] [Indexed: 06/10/2023]
Abstract
The ENCODE project has made important new estimates of human genome functionality, now revising the percentage considered functional to more than 80%, which is in stark contrast to the received view, which estimated that less than 10% of the conserved parts of the human genome are functional. ENCODE's unorthodox use of the notion of biological function has stirred the so-called ENCODE controversy, involving conflicting views about the correct notion of function in postgenomics. The debate hinges on the traditional philosophical contrast between the causal role (CR) and selected effects (SE) approaches. In this paper, we examine the ENCODE controversy in terms of the distinction between function monism and pluralism. We propose to apply a weak etiological account to genomic function ascriptions. In this approach, we can ascribe a function to a genomic structure of an organism if and only if performing the function persists in causally contributing to the organism's and its ancestors' fitness. In comparison to the strong etiological (i.e., the selected effects) approach, the present account does not require there to be selection for the structure in question. This is a monistic approach that enables us to avoid the main difficulties of CR, as well as SE's overdependence on natural selection, while still preserving an evolutionary-constrained notion of biological functions. Our proposal is much more moderate in accommodating the estimates of the functionality of the human genome than both ENCODE's proposal itself and the views of the critics relying on a version of the SE account of functions.
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Affiliation(s)
- Zdenka Brzović
- Department of Philosophy, Faculty of Humanities and Social Sciences, University of Rijeka, Sveučilišna avenija 4, 51000, Rijeka, Croatia.
| | - Predrag Šustar
- Department of Philosophy, Faculty of Humanities and Social Sciences, University of Rijeka, Sveučilišna avenija 4, 51000, Rijeka, Croatia.
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18
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Abstract
Background Previously, a seven-cluster pattern claiming to be a universal one in bacterial genomes has been reported. Keeping in mind the most popular theory of chloroplast origin, we checked whether a similar pattern is observed in chloroplast genomes. Results Surprisingly, eight cluster structure has been found, for chloroplasts. The pattern observed for chloroplasts differs rather significantly, from bacterial one, and from that latter observed for cyanobacteria. The structure is provided by clustering of the fragments of equal length isolated within a genome so that each fragment is converted in triplet frequency dictionary with non-overlapping triplets with no gaps in frame tiling. The points in 63-dimensional space were clustered due to elastic map technique. The eight cluster found in chloroplasts comprises the fragments of a genome bearing tRNA genes and exhibiting excessively high GC-content, in comparison to the entire genome. Conclusion Chloroplasts exhibit very specific symmetry type in distribution of coding and non-coding fragments of a genome in the space of triplet frequencies: this is mirror symmetry. Cyanobacteria may have both mirror symmetry, and the rotational symmetry typical for other bacteria.
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Affiliation(s)
- Michael G Sadovsky
- Institute of computational modelling SB RAS, Akademgorodok, Krasnoyarsk, 660036, Russia. .,Siberian federal university, Svobodny prosp. 79, Krasnoyarsk, 660041, Russia. .,V.F.Voino-Yasenetsky Krasnoyarsk State Medical University, P. Zheleznjaka str. 1, Krasnoyarsk, 660022, Russia.
| | - Maria Yu Senashova
- Institute of computational modelling SB RAS, Akademgorodok, Krasnoyarsk, 660036, Russia
| | - Andrew V Malyshev
- Institute of computational modelling SB RAS, Akademgorodok, Krasnoyarsk, 660036, Russia
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19
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Keeling DM, Garza P, Nartey CM, Carvunis AR. The meanings of 'function' in biology and the problematic case of de novo gene emergence. eLife 2019; 8:e47014. [PMID: 31674305 PMCID: PMC6824840 DOI: 10.7554/elife.47014] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 10/11/2019] [Indexed: 12/24/2022] Open
Abstract
The word function has many different meanings in molecular biology. Here we explore the use of this word (and derivatives like functional) in research papers about de novo gene birth. Based on an analysis of 20 abstracts we propose a simple lexicon that, we believe, will help scientists and philosophers discuss the meaning of function more clearly.
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Affiliation(s)
- Diane Marie Keeling
- Department of Communication Studies, College of Arts & SciencesUniversity of San DiegoSan DiegoUnited States
| | | | | | - Anne-Ruxandra Carvunis
- Department of Computational and Systems BiologyUniversity of PittsburghPittsburghUnited States
- Pittsburgh Center for Evolutionary Biology and MedicineUniversity of Pittsburgh School of MedicinePittsburghUnited States
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20
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Lieberman-Lazarovich M, Yahav C, Israeli A, Efroni I. Deep Conservation of cis-Element Variants Regulating Plant Hormonal Responses. THE PLANT CELL 2019; 31:2559-2572. [PMID: 31467248 PMCID: PMC6881130 DOI: 10.1105/tpc.19.00129] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 08/27/2019] [Indexed: 05/14/2023]
Abstract
Phytohormones regulate many aspects of plant life by activating transcription factors (TFs) that bind sequence-specific response elements (REs) in regulatory regions of target genes. Despite their short length, REs are degenerate, with a core of just 3 to 4 bp. This degeneracy is paradoxical, as it reduces specificity and REs are extremely common in the genome. To study whether RE degeneracy might serve a biological function, we developed an algorithm for the detection of regulatory sequence conservation and applied it to phytohormone REs in 45 angiosperms. Surprisingly, we found that specific RE variants are highly conserved in core hormone response genes. Experimental evidence showed that specific variants act to regulate the magnitude and spatial profile of hormonal response in Arabidopsis (Arabidopsis thaliana) and tomato (Solanum lycopersicum). Our results suggest that hormone-regulated TFs bind a spectrum of REs, each coding for a distinct transcriptional response profile. Our approach has implications for precise genome editing and for rational promoter design.
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Affiliation(s)
- Michal Lieberman-Lazarovich
- Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, The Hebrew University, Rehovot 7610001, Israel
| | - Chen Yahav
- Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, The Hebrew University, Rehovot 7610001, Israel
| | - Alon Israeli
- Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, The Hebrew University, Rehovot 7610001, Israel
| | - Idan Efroni
- Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, The Hebrew University, Rehovot 7610001, Israel
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21
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Hatje K, Mühlhausen S, Simm D, Kollmar M. The Protein-Coding Human Genome: Annotating High-Hanging Fruits. Bioessays 2019; 41:e1900066. [PMID: 31544971 DOI: 10.1002/bies.201900066] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 08/07/2019] [Indexed: 12/19/2022]
Abstract
The major transcript variants of human protein-coding genes are annotated to a certain degree of accuracy combining manual curation, transcript data, and proteomics evidence. However, there is considerable disagreement on the annotation of about 2000 genes-they can be protein-coding, noncoding, or pseudogenes-and on the annotation of most of the predicted alternative transcripts. Pure transcriptome mapping approaches seem to be limited in discriminating functional expression from noise. These limitations have partially been overcome by dedicated algorithms to detect alternative spliced micro-exons and wobble splice variants. Recently, knowledge about splice mechanism and protein structure are incorporated into an algorithm to predict neighboring homologous exons, often spliced in a mutually exclusive manner. Predicted exons are evaluated by transcript data, structural compatibility, and evolutionary conservation, revealing hundreds of novel coding exons and splice mechanism re-assignments. The emerging human pan-genome is necessitating distinctive annotations incorporating differences between individuals and between populations.
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Affiliation(s)
- Klas Hatje
- Roche Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Grenzacherstr. 124, 4070, Basel, Switzerland
| | - Stefanie Mühlhausen
- Group Systems Biology of Motor Proteins, Department of NMR-based Structural Biology, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Dominic Simm
- Group Systems Biology of Motor Proteins, Department of NMR-based Structural Biology, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.,Theoretical Computer Science and Algorithmic Methods, Institute of Computer Science, Georg-August-University Göttingen, Goldschmidtstr. 7, 37077, Göttingen, Germany
| | - Martin Kollmar
- Group Systems Biology of Motor Proteins, Department of NMR-based Structural Biology, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
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22
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Murillo-Maldonado JM, Riesgo-Escovar JR. The various and shared roles of lncRNAs during development. Dev Dyn 2019; 248:1059-1069. [PMID: 31454122 DOI: 10.1002/dvdy.108] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 08/08/2019] [Accepted: 08/20/2019] [Indexed: 01/03/2023] Open
Abstract
lncRNAs, genes transcribed but not translated, longer than 200 nucleotides, are classified as a separate class of nonprotein coding genes. Since their discovery, largely from RNAseq data, a number of pioneer studies have begun to unravel its myriad functions, centered on gene expression regulation, suggesting developmental and evolutionary conservation. Since they do not code for proteins and have no open reading frames, their functional constraints likely differ from that of protein coding genes, or of genes where the majority of the nucleotide sequence is required for function, like tRNAs. This has complicated assessment of both developmental and evolutionary conservation, and the identification of homologs in different species. Here we argue that other characteristics: general synteny and particular chromosomal placement regardless of sequence, sequence micro-motifs, and secondary structure allow for "homologs" to be identified and compared, confirming developmental and evolutionary conservation of lncRNAs. We conclude exemplifying a case in point: that of the evolutionarily conserved lncRNA acal, characterized and required for embryogenesis in Drosophila.
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Affiliation(s)
- Juan M Murillo-Maldonado
- Developmental Neurobiology and Neurophysiology, Instituto de Neurobología, Campus UNAM Juriquilla, Universidad Nacional Autónoma de Mexico, Santiago de Querétaro, Querétaro, Mexico
| | - Juan R Riesgo-Escovar
- Developmental Neurobiology and Neurophysiology, Instituto de Neurobología, Campus UNAM Juriquilla, Universidad Nacional Autónoma de Mexico, Santiago de Querétaro, Querétaro, Mexico
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23
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Hoeppner MP, Denisenko E, Gardner PP, Schmeier S, Poole AM. An Evaluation of Function of Multicopy Noncoding RNAs in Mammals Using ENCODE/FANTOM Data and Comparative Genomics. Mol Biol Evol 2019; 35:1451-1462. [PMID: 29617896 PMCID: PMC5967550 DOI: 10.1093/molbev/msy046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Mammalian diversification has coincided with a rapid proliferation of various types of noncoding RNAs, including members of both snRNAs and snoRNAs. The significance of this expansion however remains obscure. While some ncRNA copy-number expansions have been linked to functionally tractable effects, such events may equally likely be neutral, perhaps as a result of random retrotransposition. Hindering progress in our understanding of such observations is the difficulty in establishing function for the diverse features that have been identified in our own genome. Projects such as ENCODE and FANTOM have revealed a hidden world of genomic expression patterns, as well as a host of other potential indicators of biological function. However, such projects have been criticized, particularly from practitioners in the field of molecular evolution, where many suspect these data provide limited insight into biological function. The molecular evolution community has largely taken a skeptical view, thus it is important to establish tests of function. We use a range of data, including data drawn from ENCODE and FANTOM, to examine the case for function for the recent copy number expansion in mammals of six evolutionarily ancient RNA families involved in splicing and rRNA maturation. We use several criteria to assess evidence for function: conservation of sequence and structure, genomic synteny, evidence for transposition, and evidence for species-specific expression. Applying these criteria, we find that only a minority of loci show strong evidence for function and that, for the majority, we cannot reject the null hypothesis of no function.
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Affiliation(s)
- Marc P Hoeppner
- Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Elena Denisenko
- Institute of Natural and Mathematical Sciences, Massey University, Auckland, New Zealand
| | - Paul P Gardner
- Biomolecular Interaction Centre, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Sebastian Schmeier
- Institute of Natural and Mathematical Sciences, Massey University, Auckland, New Zealand
| | - Anthony M Poole
- Bioinformatics Institute, School of Biological Sciences, University of Auckland, Auckland, New Zealand
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24
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Wang Z, Ren B, Huang J, Yin R, Jiang F, Zhang Q. LncRNA DUXAP10 modulates cell proliferation in esophageal squamous cell carcinoma through epigenetically silencing p21. Cancer Biol Ther 2018; 19:998-1005. [PMID: 30215547 DOI: 10.1080/15384047.2018.1470723] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Esophageal Squamous Cell Carcinoma (ESCC) belongs to malignant tumor of human digestive system. It has greatly threatened human health both mentally and physically. Long non-coding RNAs have been discovered to be special molecular regulators in various cancers, including ESCC. LncRNA DUXAP10 is a newfound RNA, which is able to improve the progression of cancers 1-3 . In this study, DUXAP10 was certified to be upregulated in ESCC tissues and cells. Besides, it was positively correlated with short survival time. Moreover, down-expression of DUXAP10 contributed to decreased cell proliferation and metastasis. Silenced DUXAP10 led to increased apoptosis rate and stagnation of cell cycle. Results of mechanism experiments suggested that DUXAP10 motivated ESCC progression through recruiting enhancer of zeste homolog 2 (EZH2) to the promoter of p21. Our findings suggested that the pseudogene-derived from lncRNA DUXAP10 drove the biological progression of ESCC. DUXAP10 was likely to be a potential therapeutic target for ESCC.
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Affiliation(s)
- Zhongqiu Wang
- a Department of Thoracic Surgery , Jiangsu Cancer Hospital, Institute Affiliated to Nanjing Medical University, Cancer Institute of Jiangsu Province. No.42 , Baiziting Road, Xuanwu District, 210009, Nanjing , Jiangsu Province , PR China
| | - Binhui Ren
- a Department of Thoracic Surgery , Jiangsu Cancer Hospital, Institute Affiliated to Nanjing Medical University, Cancer Institute of Jiangsu Province. No.42 , Baiziting Road, Xuanwu District, 210009, Nanjing , Jiangsu Province , PR China
| | - Jianfeng Huang
- a Department of Thoracic Surgery , Jiangsu Cancer Hospital, Institute Affiliated to Nanjing Medical University, Cancer Institute of Jiangsu Province. No.42 , Baiziting Road, Xuanwu District, 210009, Nanjing , Jiangsu Province , PR China
| | - Rong Yin
- a Department of Thoracic Surgery , Jiangsu Cancer Hospital, Institute Affiliated to Nanjing Medical University, Cancer Institute of Jiangsu Province. No.42 , Baiziting Road, Xuanwu District, 210009, Nanjing , Jiangsu Province , PR China
| | - Feng Jiang
- a Department of Thoracic Surgery , Jiangsu Cancer Hospital, Institute Affiliated to Nanjing Medical University, Cancer Institute of Jiangsu Province. No.42 , Baiziting Road, Xuanwu District, 210009, Nanjing , Jiangsu Province , PR China
| | - Qin Zhang
- a Department of Thoracic Surgery , Jiangsu Cancer Hospital, Institute Affiliated to Nanjing Medical University, Cancer Institute of Jiangsu Province. No.42 , Baiziting Road, Xuanwu District, 210009, Nanjing , Jiangsu Province , PR China
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25
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Correlated Selection on Amino Acid Deletion and Replacement in Mammalian Protein Sequences. J Mol Evol 2018; 86:365-378. [PMID: 29955898 DOI: 10.1007/s00239-018-9853-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 06/21/2018] [Indexed: 10/28/2022]
Abstract
A low ratio of nonsynonymous and synonymous substitution rates (dN/dS) at a codon is an indicator of functional constraint caused by purifying selection. Intuitively, the functional constraint would also be expected to prevent such a codon from being deleted. However, to the best of our knowledge, the correlation between the rates of deletion and substitution has never actually been estimated. Here, we use 8595 protein-coding region sequences from nine mammalian species to examine the relationship between deletion rate and dN/dS. We find significant positive correlations at the levels of both sites and genes. We compared our data against controls consisting of simulated coding sequences evolving along identical phylogenetic trees, where deletions occur independently of substitutions. A much weaker correlation was found in the corresponding simulated sequences, probably caused by alignment errors. In the real data, the correlations cannot be explained by alignment errors. Separate investigations on nonsynonymous (dN) and synonymous (dS) substitution rates indicate that the correlation is most likely due to a similarity in patterns of selection rather than in mutation rates.
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26
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Sverdlov ED. Unsolvable Problems of Biology: It Is Impossible to Create Two Identical Organisms, to Defeat Cancer, or to Map Organisms onto Their Genomes. BIOCHEMISTRY (MOSCOW) 2018; 83:370-380. [PMID: 29626924 DOI: 10.1134/s0006297918040089] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The review is devoted to unsolvable problems of biology. 1) Problems unsolvable due to stochastic mutations occurring during DNA replication that make it impossible to create two identical organisms or even two identical complex cells (Sverdlov, E. D. (2009) Biochemistry (Moscow), 74, 939-944) and to "defeat" cancer. 2) Problems unsolvable due to multiple interactions in complex systems leading to the appearance of unpredictable emergent properties that prevent establishment of unambiguous relationships between the genetic architecture and phenotypic manifestation of the genome and make impossible to predict with certainty responses of the organism, its parts, or pathological processes to external factors. 3) Problems unsolvable because of the uncertainty principle and observer effect in biology, due to which it is impossible to obtain adequate information about cells in their tissue microenvironment by isolating and analyzing individual cells. In particular, we cannot draw conclusions on the properties of stem cells in their niches based on the properties of stem cell cultures. A strategy is proposed for constructing the pattern most closely approximated to the relationship of genotypes with their phenotypes by designing networks of intermediate phenotypes (endophenotypes).
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Affiliation(s)
- E D Sverdlov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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27
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Same-Sex Twin Pair Phenotypic Correlations are Consistent with Human Y Chromosome Promoting Phenotypic Heterogeneity. Evol Biol 2018. [DOI: 10.1007/s11692-018-9454-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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28
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Robicheau BM, Susko E, Harrigan AM, Snyder M. Ribosomal RNA Genes Contribute to the Formation of Pseudogenes and Junk DNA in the Human Genome. Genome Biol Evol 2018; 9:380-397. [PMID: 28204512 PMCID: PMC5381670 DOI: 10.1093/gbe/evw307] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2016] [Indexed: 12/20/2022] Open
Abstract
Approximately 35% of the human genome can be identified as sequence devoid of a selected-effect function, and not derived from transposable elements or repeated sequences. We provide evidence supporting a known origin for a fraction of this sequence. We show that: 1) highly degraded, but near full length, ribosomal DNA (rDNA) units, including both 45S and Intergenic Spacer (IGS), can be found at multiple sites in the human genome on chromosomes without rDNA arrays, 2) that these rDNA sequences have a propensity for being centromere proximal, and 3) that sequence at all human functional rDNA array ends is divergent from canonical rDNA to the point that it is pseudogenic. We also show that small sequence strings of rDNA (from 45S + IGS) can be found distributed throughout the genome and are identifiable as an “rDNA-like signal”, representing 0.26% of the q-arm of HSA21 and ∼2% of the total sequence of other regions tested. The size of sequence strings found in the rDNA-like signal intergrade into the size of sequence strings that make up the full-length degrading rDNA units found scattered throughout the genome. We conclude that the displaced and degrading rDNA sequences are likely of a similar origin but represent different stages in their evolution towards random sequence. Collectively, our data suggests that over vast evolutionary time, rDNA arrays contribute to the production of junk DNA. The concept that the production of rDNA pseudogenes is a by-product of concerted evolution represents a previously under-appreciated process; we demonstrate here its importance.
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Affiliation(s)
- Brent M Robicheau
- Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada
| | - Edward Susko
- Center for Comparative Genomics and Evolutionary Bioinformatics, Department of Mathematics and Statistics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Amye M Harrigan
- Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada
| | - Marlene Snyder
- Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada
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29
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du Mee DJM, Ivanov M, Parker JP, Buratowski S, Marquardt S. Efficient termination of nuclear lncRNA transcription promotes mitochondrial genome maintenance. eLife 2018; 7:31989. [PMID: 29504936 PMCID: PMC5837560 DOI: 10.7554/elife.31989] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 02/08/2018] [Indexed: 12/27/2022] Open
Abstract
Most DNA in the genomes of higher organisms does not code for proteins. RNA Polymerase II (Pol II) transcribes non-coding DNA into long non-coding RNAs (lncRNAs), but biological roles of lncRNA are unclear. We find that mutations in the yeast lncRNA CUT60 result in poor growth. Defective termination of CUT60 transcription causes read-through transcription across the ATP16 gene promoter. Read-through transcription localizes chromatin signatures associated with Pol II elongation to the ATP16 promoter. The act of Pol II elongation across this promoter represses functional ATP16 expression by a Transcriptional Interference (TI) mechanism. Atp16p function in the mitochondrial ATP-synthase complex promotes mitochondrial DNA stability. ATP16 repression by TI through inefficient termination of CUT60 therefore triggers mitochondrial genome loss. Our results expand the functional and mechanistic implications of non-coding DNA in eukaryotes by highlighting termination of nuclear lncRNA transcription as mechanism to stabilize an organellar genome.
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Affiliation(s)
- Dorine Jeanne Mariëtte du Mee
- Department of Plant and Environmental Sciences, Copenhagen Plant Science Centre, University of Copenhagen, Frederiksberg, Denmark
| | - Maxim Ivanov
- Department of Plant and Environmental Sciences, Copenhagen Plant Science Centre, University of Copenhagen, Frederiksberg, Denmark
| | - Joseph Paul Parker
- Department of Plant and Environmental Sciences, Copenhagen Plant Science Centre, University of Copenhagen, Frederiksberg, Denmark
| | - Stephen Buratowski
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
| | - Sebastian Marquardt
- Department of Plant and Environmental Sciences, Copenhagen Plant Science Centre, University of Copenhagen, Frederiksberg, Denmark
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30
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Graur D. An Upper Limit on the Functional Fraction of the Human Genome. Genome Biol Evol 2017; 9:1880-1885. [PMID: 28854598 PMCID: PMC5570035 DOI: 10.1093/gbe/evx121] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2017] [Indexed: 12/13/2022] Open
Abstract
For the human population to maintain a constant size from generation to generation, an increase in fertility must compensate for the reduction in the mean fitness of the population caused, among others, by deleterious mutations. The required increase in fertility due to this mutational load depends on the number of sites in the genome that are functional, the mutation rate, and the fraction of deleterious mutations among all mutations in functional regions. These dependencies and the fact that there exists a maximum tolerable replacement level fertility can be used to put an upper limit on the fraction of the human genome that can be functional. Mutational load considerations lead to the conclusion that the functional fraction within the human genome cannot exceed 15%.
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Affiliation(s)
- Dan Graur
- Department of Biology and Biochemistry, University of Houston, TX
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31
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Liu Z, Zhang J. Most m6A RNA Modifications in Protein-Coding Regions Are Evolutionarily Unconserved and Likely Nonfunctional. Mol Biol Evol 2017; 35:666-675. [PMID: 29228327 DOI: 10.1093/molbev/msx320] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Methylation of the adenosine base at the nitrogen-6 position (m6A) is the most prevalent internal posttranscriptional modification of mRNAs in many eukaryotes. Despite the rapid progress in the transcriptome-wide mapping of m6As, identification of proteins responsible for writing, reading, and erasing m6As, and elucidation of m6A functions in splicing, RNA stability, translation, and other processes, it is unknown whether most observed m6A modifications are functional. To address this question, we respectively analyze the evolutionary conservation of yeast and human m6As in protein-coding regions. Relative to comparable unmethylated As, m6As are overall no more conserved in yeasts and only slightly more conserved in mammals. Furthermore, yeast m6As and comparable unmethylated As have no significant difference in single nucleotide polymorphism (SNP) density or SNP site frequency spectrum. The same is true in human. The methylation status of a gene, not necessarily the specific sites methylated in the gene, is subject to purifying selection for no more than ∼20% of m6A-modified genes. These observations suggest that most m6A modifications in protein-coding regions are nonfunctional and nonadaptive, probably resulting from off-target activities of m6A methyltransferases. In addition, our reanalysis invalidates the recent claim of positive selection for newly acquired m6A modifications in human evolution. Regarding the small number of evolutionarily conserved m6As, evidence suggests that a large proportion of them are likely functional; they should be prioritized in future functional characterizations of m6As. Together, these findings have important implications for understanding the biological significance of m6A and other posttranscriptional modifications.
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Affiliation(s)
- Zhen Liu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
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32
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Abstract
The idea that much of our genome is irrelevant to fitness-is not the product of positive natural selection at the organismal level-remains viable. Claims to the contrary, and specifically that the notion of "junk DNA" should be abandoned, are based on conflating meanings of the word "function". Recent estimates suggest that perhaps 90% of our DNA, though biochemically active, does not contribute to fitness in any sequence-dependent way, and possibly in no way at all. Comparisons to vertebrates with much larger and smaller genomes (the lungfish and the pufferfish) strongly align with such a conclusion, as they have done for the last half-century.
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Affiliation(s)
- W Ford Doolittle
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
| | - Tyler D P Brunet
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of History and Philosophy of Science, University of Cambridge, Cambridge, UK
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33
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Deichmann U. Hierarchy, determinism, and specificity in theories of development and evolution. HISTORY AND PHILOSOPHY OF THE LIFE SCIENCES 2017; 39:33. [PMID: 29038982 DOI: 10.1007/s40656-017-0160-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The concepts of hierarchical organization, genetic determinism and biological specificity (for example of species, biologically relevant macromolecules, or genes) have played a crucial role in biology as a modern experimental science since its beginnings in the nineteenth century. The idea of genetic information (specificity) and genetic determination was at the basis of molecular biology that developed in the 1940s with macromolecules, viruses and prokaryotes as major objects of research often labelled "reductionist". However, the concepts have been marginalized or rejected in some of the research that in the late 1960s began to focus additionally on the molecularization of complex biological structures and functions using systems approaches. This paper challenges the view that 'molecular reductionism' has been successfully replaced by holism and a focus on the collective behaviour of cellular entities. It argues instead that there are more fertile replacements for molecular 'reductionism', in which genomics, embryology, biochemistry, and computer science intertwine and result in research that is as exact and causally predictive as earlier molecular biology.
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Affiliation(s)
- Ute Deichmann
- Jacques Loeb Centre for the History and Philosophy of the Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, 84105, Beer Sheva, Israel.
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34
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Sayadi A, Immonen E, Tellgren-Roth C, Arnqvist G. The Evolution of Dark Matter in the Mitogenome of Seed Beetles. Genome Biol Evol 2017; 9:2697-2706. [PMID: 29048527 PMCID: PMC5737749 DOI: 10.1093/gbe/evx205] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2017] [Indexed: 12/14/2022] Open
Abstract
Animal mitogenomes are generally thought of as being economic and optimized for rapid replication and transcription. We use long-read sequencing technology to assemble the remarkable mitogenomes of four species of seed beetles. These are the largest circular mitogenomes ever assembled in insects, ranging from 24,496 to 26,613 bp in total length, and are exceptional in that some 40% consists of non-coding DNA. The size expansion is due to two very long intergenic spacers (LIGSs), rich in tandem repeats. The two LIGSs are present in all species but vary greatly in length (114-10,408 bp), show very low sequence similarity, divergent tandem repeat motifs, a very high AT content and concerted length evolution. The LIGSs have been retained for at least some 45 my but must have undergone repeated reductions and expansions, despite strong purifying selection on protein coding mtDNA genes. The LIGSs are located in two intergenic sites where a few recent studies of insects have also reported shorter LIGSs (>200 bp). These sites may represent spaces that tolerate neutral repeat array expansions or, alternatively, the LIGSs may function to allow a more economic translational machinery. Mitochondrial respiration in adult seed beetles is based almost exclusively on fatty acids, which reduces the need for building complex I of the oxidative phosphorylation pathway (NADH dehydrogenase). One possibility is thus that the LIGSs may allow depressed transcription of NAD genes. RNA sequencing showed that LIGSs are partly transcribed and transcriptional profiling suggested that all seven mtDNA NAD genes indeed show low levels of transcription and co-regulation of transcription across sexes and tissues.
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Affiliation(s)
- Ahmed Sayadi
- Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Sweden
| | - Elina Immonen
- Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Sweden
| | - Christian Tellgren-Roth
- National Genomics Infrastructure, Science for Life Laboratory, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Göran Arnqvist
- Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Sweden
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35
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Garrido-Ramos MA. Satellite DNA: An Evolving Topic. Genes (Basel) 2017; 8:genes8090230. [PMID: 28926993 PMCID: PMC5615363 DOI: 10.3390/genes8090230] [Citation(s) in RCA: 227] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/12/2017] [Accepted: 09/13/2017] [Indexed: 12/22/2022] Open
Abstract
Satellite DNA represents one of the most fascinating parts of the repetitive fraction of the eukaryotic genome. Since the discovery of highly repetitive tandem DNA in the 1960s, a lot of literature has extensively covered various topics related to the structure, organization, function, and evolution of such sequences. Today, with the advent of genomic tools, the study of satellite DNA has regained a great interest. Thus, Next-Generation Sequencing (NGS), together with high-throughput in silico analysis of the information contained in NGS reads, has revolutionized the analysis of the repetitive fraction of the eukaryotic genomes. The whole of the historical and current approaches to the topic gives us a broad view of the function and evolution of satellite DNA and its role in chromosomal evolution. Currently, we have extensive information on the molecular, chromosomal, biological, and population factors that affect the evolutionary fate of satellite DNA, knowledge that gives rise to a series of hypotheses that get on well with each other about the origin, spreading, and evolution of satellite DNA. In this paper, I review these hypotheses from a methodological, conceptual, and historical perspective and frame them in the context of chromosomal organization and evolution.
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Affiliation(s)
- Manuel A Garrido-Ramos
- Departamento de Genética, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain.
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36
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Lian Y, Xu Y, Xiao C, Xia R, Gong H, Yang P, Chen T, Wu D, Cai Z, Zhang J, Wang K. The pseudogene derived from long non-coding RNA DUXAP10 promotes colorectal cancer cell growth through epigenetically silencing of p21 and PTEN. Sci Rep 2017; 7:7312. [PMID: 28779166 PMCID: PMC5544748 DOI: 10.1038/s41598-017-07954-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 07/03/2017] [Indexed: 12/24/2022] Open
Abstract
Recently, substantial evidence has demonstrated that pseudogene derived lncRNAs are crucial regulators of cancer development and progression. DUXAP10,a pseudogene derived long non-coding RNA(lncRNA), is overexpression in colorectal cancer (CRC), but its expression pattern, biological function and underlying mechanism in CRC is still undetermined. In this study, we observed that DUXAP10 was up-regulated in CRC tissues which was positively correlated with advanced pathological stages, larger tumor sizes and lymph node metastasis. Additionally, knockdown of DUXAP10 inhibited cell proliferation, induced cell apoptosis and increase the number of G0/G1 cells significantly in the HCT116 and SW480 cell lines. Moreover, DUXAP10 silencing inhibited tumor growth in vivo. Further mechanism study showed that, by binding to histone demethylase lysine-specific demethylase 1 (LSD1), DUXAP10 promote CRC cell growth and reduced cell apoptosis through silencing the expression of p21 and phosphatase and tensin homolog (PTEN) tumor suppressor. Our findings suggested that the pseudogene-derived from lncRNA DUXAP10 promotes the biological progression of CRC and is likely to be a potential therapeutic target for CRC intervention.
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Affiliation(s)
- Yifan Lian
- Department of Gastroenterology, Zhongshan Hospital affiliated to Xiamen University, Xiamen, 361004, Fujian, People's Republic of China.,Department of Oncology, Second Affiliated Hospital, Nanjing Medical University, Nanjing, 210000, Jiangsu, People's Republic of China
| | - Yetao Xu
- Department of Obstetrics and Gynecology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, 210000, Jiangsu, People's Republic of China
| | - Chuanxing Xiao
- Department of Gastroenterology, Zhongshan Hospital affiliated to Xiamen University, Xiamen, 361004, Fujian, People's Republic of China
| | - Rui Xia
- Department of Laboratory, Nanjing Chest Hospital, Nanjing, 210029, Jiangsu, People's Republic of China
| | - Huangbo Gong
- Department of General Surgery, Second Affiliated Hospital, Nanjing Medical University, Nanjing, 210000, Jiangsu, People's Republic of China
| | - Peng Yang
- Department of General Surgery, Second Affiliated Hospital, Nanjing Medical University, Nanjing, 210000, Jiangsu, People's Republic of China
| | - Tao Chen
- Department of General Surgery, Second Affiliated Hospital, Nanjing Medical University, Nanjing, 210000, Jiangsu, People's Republic of China
| | - Dongdong Wu
- Department of General Surgery, Second Affiliated Hospital, Nanjing Medical University, Nanjing, 210000, Jiangsu, People's Republic of China
| | - Zeling Cai
- Department of General Surgery, Second Affiliated Hospital, Nanjing Medical University, Nanjing, 210000, Jiangsu, People's Republic of China
| | - Jianping Zhang
- Department of General Surgery, Second Affiliated Hospital, Nanjing Medical University, Nanjing, 210000, Jiangsu, People's Republic of China
| | - Keming Wang
- Department of Oncology, Second Affiliated Hospital, Nanjing Medical University, Nanjing, 210000, Jiangsu, People's Republic of China.
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37
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Chorev M, Joseph Bekker A, Goldberger J, Carmel L. Identification of introns harboring functional sequence elements through positional conservation. Sci Rep 2017. [PMID: 28646210 PMCID: PMC5482813 DOI: 10.1038/s41598-017-04476-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Many human introns carry out a function, in the sense that they are critical to maintain normal cellular activity. Their identification is fundamental to understanding cellular processes and disease. However, being noncoding elements, such functional introns are poorly predicted based on traditional approaches of sequence and structure conservation. Here, we generated a dataset of human functional introns that carry out different types of functions. We showed that functional introns share common characteristics, such as higher positional conservation along the coding sequence and reduced loss rates, regardless of their specific function. A unique property of the data is that if an intron is unknown to be functional, it still does not mean that it is indeed non-functional. We developed a probabilistic framework that explicitly accounts for this unique property, and predicts which specific human introns are functional. We show that we successfully predict function even when the algorithm is trained on introns with a different type of function. This ability has many implications in studying regulatory networks, gene regulation, the effect of mutations outside exons on human disease, and on our general understanding of intron evolution and their functional exaptation in mammals.
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Affiliation(s)
- Michal Chorev
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 91904, Israel.,The Rachel and Selim Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, 91904, Israel
| | | | - Jacob Goldberger
- Faculty of Engineering, Bar-Ilan University, Ramat Gan, 52900, Israel
| | - Liran Carmel
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem, 91904, Israel.
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38
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Savisaar R, Hurst LD. Estimating the prevalence of functional exonic splice regulatory information. Hum Genet 2017; 136:1059-1078. [PMID: 28405812 PMCID: PMC5602102 DOI: 10.1007/s00439-017-1798-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 04/04/2017] [Indexed: 12/14/2022]
Abstract
In addition to coding information, human exons contain sequences necessary for correct splicing. These elements are known to be under purifying selection and their disruption can cause disease. However, the density of functional exonic splicing information remains profoundly uncertain. Several groups have experimentally investigated how mutations at different exonic positions affect splicing. They have found splice information to be distributed widely in exons, with one estimate putting the proportion of splicing-relevant nucleotides at >90%. These results suggest that splicing could place a major pressure on exon evolution. However, analyses of sequence conservation have concluded that the need to preserve splice regulatory signals only slightly constrains exon evolution, with a resulting decrease in the average human rate of synonymous evolution of only 1–4%. Why do these two lines of research come to such different conclusions? Among other reasons, we suggest that the methods are measuring different things: one assays the density of sites that affect splicing, the other the density of sites whose effects on splicing are visible to selection. In addition, the experimental methods typically consider short exons, thereby enriching for nucleotides close to the splice junction, such sites being enriched for splice-control elements. By contrast, in part owing to correction for nucleotide composition biases and to the assumption that constraint only operates on exon ends, the conservation-based methods can be overly conservative.
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Affiliation(s)
- Rosina Savisaar
- The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK.
| | - Laurence D Hurst
- The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK
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39
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Abstract
Chromatin in the interphase nucleus is organised as a hierarchical series of structural domains, including self-interacting domains called topologically associating domains (TADs). This arrangement is thought to bring enhancers into closer physical proximity with their target genes, which often are located hundreds of kilobases away in linear genomic distance. TADs are demarcated by boundary regions bound by architectural proteins, such as CTCF and cohesin, although much remains to be discovered about the structure and function of these domains. Recent studies of TAD boundaries disrupted in engineered mouse models show that boundary mutations can recapitulate human developmental disorders as a result of aberrant promoter-enhancer interactions in the affected TADs. Similar boundary disruptions in certain cancers can result in oncogene overexpression, and CTCF binding sites at boundaries appear to be hyper-mutated across cancers. Further insights into chromatin organisation, in parallel with accumulating whole genome sequence data for disease cohorts, are likely to yield additional valuable insights into the roles of noncoding sequence variation in human disease.
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Affiliation(s)
- Vera B Kaiser
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Colin A Semple
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
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40
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França GS, Hinske LC, Galante PAF, Vibranovski MD. Unveiling the Impact of the Genomic Architecture on the Evolution of Vertebrate microRNAs. Front Genet 2017; 8:34. [PMID: 28377786 PMCID: PMC5359303 DOI: 10.3389/fgene.2017.00034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 03/09/2017] [Indexed: 12/12/2022] Open
Abstract
Eukaryotic genomes frequently exhibit interdependency between transcriptional units, as evidenced by regions of high gene density. It is well recognized that vertebrate microRNAs (miRNAs) are usually embedded in those regions. Recent work has shown that the genomic context is of utmost importance to determine miRNA expression in time and space, thus affecting their evolutionary fates over long and short terms. Consequently, understanding the inter- and intraspecific changes on miRNA genomic architecture may bring novel insights on the basic cellular processes regulated by miRNAs, as well as phenotypic evolution and disease-related mechanisms.
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Affiliation(s)
- Gustavo S França
- Departamento de Genética e Biologia Evolutiva, Universidade de São Paulo São Paulo, Brazil
| | - Ludwig C Hinske
- Department of Anesthesiology, Clinic of the University of Munich, Ludwig Maximilian University of Munich Munich, Germany
| | - Pedro A F Galante
- Centro de Oncologia Molecular, Hospital Sírio-Libanês São Paulo, Brazil
| | - Maria D Vibranovski
- Departamento de Genética e Biologia Evolutiva, Universidade de São Paulo São Paulo, Brazil
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41
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Koonin EV. Splendor and misery of adaptation, or the importance of neutral null for understanding evolution. BMC Biol 2016; 14:114. [PMID: 28010725 PMCID: PMC5180405 DOI: 10.1186/s12915-016-0338-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The study of any biological features, including genomic sequences, typically revolves around the question: what is this for? However, population genetic theory, combined with the data of comparative genomics, clearly indicates that such a "pan-adaptationist" approach is a fallacy. The proper question is: how has this sequence evolved? And the proper null hypothesis posits that it is a result of neutral evolution: that is, it survives by sheer chance provided that it is not deleterious enough to be efficiently purged by purifying selection. To claim adaptation, the neutral null has to be falsified. The adaptationist fallacy can be costly, inducing biologists to relentlessly seek function where there is none.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, 20894, USA.
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42
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43
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Smith DR. The mutational hazard hypothesis of organelle genome evolution: 10 years on. Mol Ecol 2016; 25:3769-75. [PMID: 27357487 DOI: 10.1111/mec.13742] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 05/14/2016] [Accepted: 06/22/2016] [Indexed: 12/12/2022]
Abstract
Why is there such a large variation in size and noncoding DNA content among organelle genomes? One explanation is that this genomic variation results from differences in the rates of organelle mutation and random genetic drift, as opposed to being the direct product of natural selection. Along these lines, the mutational hazard hypothesis (MHH) holds that 'excess' DNA is a mutational liability (because it increases the potential for harmful mutations) and, thus, has a greater tendency to accumulate in an organelle system with a low mutation rate as opposed to one with a high rate of mutation. Various studies have explored this hypothesis and, more generally, the relationship between organelle genome architecture and the mode and efficiency of organelle DNA repair. Although some of these investigations are in agreement with the MHH, others have contradicted it; nevertheless, they support a central role of mutation, DNA maintenance pathways and random genetic drift in fashioning organelle chromosomes. Arguably, one of the most important contributions of the MHH is that it has sparked crucial, widespread discussions about the importance of nonadaptive processes in genome evolution.
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Affiliation(s)
- David Roy Smith
- Department of Biology, University of Western Ontario, London, ON, N6A 5B7, Canada
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44
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Abstract
Human genome sequencing is routine and will soon be a staple in research and clinical genetics. However, the promise of sequencing is often just that, with genome data routinely failing to reveal useful insights about disease in general or a person's health in particular. Nowhere is this chasm between promise and progress more evident than in the designation, "variant of uncertain significance" (VUS). Although it serves an important role, careful consideration of VUS reveals it to be a nebulous description of genomic information and its relationship to disease, symptomatic of our inability to make even crude quantitative assertions about the disease risks conferred by many genetic variants. In this perspective, I discuss the challenge of "variant interpretation" and the value of comparative and functional genomic information in meeting that challenge. Although already essential, genomic annotations will become even more important as our analytical focus widens beyond coding exons. Combined with more genotype and phenotype data, they will help facilitate more quantitative and insightful assessments of the contributions of genetic variants to disease.
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Affiliation(s)
- Gregory M Cooper
- HudsonAlpha Institute for Biotechnology, Huntsville, Alabama 35806, USA
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45
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Koonin EV. The meaning of biological information. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:rsta.2015.0065. [PMID: 26857678 PMCID: PMC4760125 DOI: 10.1098/rsta.2015.0065] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 07/27/2015] [Indexed: 06/05/2023]
Abstract
Biological information encoded in genomes is fundamentally different from and effectively orthogonal to Shannon entropy. The biologically relevant concept of information has to do with 'meaning', i.e. encoding various biological functions with various degree of evolutionary conservation. Apart from direct experimentation, the meaning, or biological information content, can be extracted and quantified from alignments of homologous nucleotide or amino acid sequences but generally not from a single sequence, using appropriately modified information theoretical formulae. For short, information encoded in genomes is defined vertically but not horizontally. Informally but substantially, biological information density seems to be equivalent to 'meaning' of genomic sequences that spans the entire range from sharply defined, universal meaning to effective meaninglessness. Large fractions of genomes, up to 90% in some plants, belong within the domain of fuzzy meaning. The sequences with fuzzy meaning can be recruited for various functions, with the meaning subsequently fixed, and also could perform generic functional roles that do not require sequence conservation. Biological meaning is continuously transferred between the genomes of selfish elements and hosts in the process of their coevolution. Thus, in order to adequately describe genome function and evolution, the concepts of information theory have to be adapted to incorporate the notion of meaning that is central to biology.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
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46
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The relativity of biological function. Theory Biosci 2015; 134:143-7. [DOI: 10.1007/s12064-015-0215-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Accepted: 09/03/2015] [Indexed: 01/09/2023]
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47
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Brunet TDP, Doolittle WF. Multilevel Selection Theory and the Evolutionary Functions of Transposable Elements. Genome Biol Evol 2015; 7:2445-57. [PMID: 26253318 PMCID: PMC4558868 DOI: 10.1093/gbe/evv152] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
One of several issues at play in the renewed debate over “junk DNA” is the organizational level at which genomic features might be seen as selected, and thus to exhibit function, as etiologically defined. The intuition frequently expressed by molecular geneticists that junk DNA is functional because it serves to “speed evolution” or as an “evolutionary repository” could be recast as a claim about selection between species (or clades) rather than within them, but this is not often done. Here, we review general arguments for the importance of selection at levels above that of organisms in evolution, and develop them further for a common genomic feature: the carriage of transposable elements (TEs). In many species, not least our own, TEs comprise a large fraction of all nuclear DNA, and whether they individually or collectively contribute to fitness—or are instead junk— is a subject of ongoing contestation. Even if TEs generally owe their origin to selfish selection at the lowest level (that of genomes), their prevalence in extant organisms and the prevalence of extant organisms bearing them must also respond to selection within species (on organismal fitness) and between species (on rates of speciation and extinction). At an even higher level, the persistence of clades may be affected (positively or negatively) by TE carriage. If indeed TEs speed evolution, it is at these higher levels of selection that such a function might best be attributed to them as a class.
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Affiliation(s)
- Tyler D P Brunet
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - W Ford Doolittle
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
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48
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Garrido-Ramos MA. Satellite DNA in Plants: More than Just Rubbish. Cytogenet Genome Res 2015; 146:153-170. [PMID: 26202574 DOI: 10.1159/000437008] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2015] [Indexed: 11/19/2022] Open
Abstract
For decades, satellite DNAs have been the hidden part of genomes. Initially considered as junk DNA, there is currently an increasing appreciation of the functional significance of satellite DNA repeats and of their sequences. Satellite DNA families accumulate in the heterochromatin in different parts of the eukaryotic chromosomes, mainly in pericentromeric and subtelomeric regions, but they also span the functional centromere. Tandem repeat sequences may spread from subtelomeric to interstitial loci, leading to the formation of chromosome-specific loci or to the accumulation in equilocal sites in different chromosomes. They also appear as the main components of the heterochromatin in the sex-specific region of sex chromosomes. Satellite DNA, required for chromosome organization, also plays a role in pairing and segregation. Some satellite repeats are transcribed and can participate in the formation and maintenance of heterochromatin structure and in the modulation of gene expression. In addition to the identification of the different satellite DNA families, their characteristics and location, we are interested in determining their impact on the genomes, by identifying the mechanisms leading to their appearance and amplification as well as in understanding how they change over time, the factors affecting these changes, and the influence exerted by the evolutionary history of the organisms. On the other hand, satellite DNA sequences are rapidly evolving sequences that may cause reproductive barriers between organisms and promote speciation. The accumulation of experimental data collected in recent years and the emergence of new approaches based on next-generation sequencing and high-throughput genome analysis are opening new perspectives that are changing our understanding of satellite DNA. This review examines recent data to provide a timely update on the overall information gathered about this part of the genome, focusing on the advances in the knowledge of its origin, its evolution, and its potential functional roles.
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49
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Orgogozo V, Morizot B, Martin A. The differential view of genotype-phenotype relationships. Front Genet 2015; 6:179. [PMID: 26042146 PMCID: PMC4437230 DOI: 10.3389/fgene.2015.00179] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 04/28/2015] [Indexed: 12/21/2022] Open
Abstract
An integrative view of diversity and singularity in the living world requires a better understanding of the intricate link between genotypes and phenotypes. Here we re-emphasize the old standpoint that the genotype-phenotype (GP) relationship is best viewed as a connection between two differences, one at the genetic level and one at the phenotypic level. As of today, predominant thinking in biology research is that multiple genes interact with multiple environmental variables (such as abiotic factors, culture, or symbionts) to produce the phenotype. Often, the problem of linking genotypes and phenotypes is framed in terms of genotype and phenotype maps, and such graphical representations implicitly bring us away from the differential view of GP relationships. Here we show that the differential view of GP relationships is a useful explanatory framework in the context of pervasive pleiotropy, epistasis, and environmental effects. In such cases, it is relevant to view GP relationships as differences embedded into differences. Thinking in terms of differences clarifies the comparison between environmental and genetic effects on phenotypes and helps to further understand the connection between genotypes and phenotypes.
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Affiliation(s)
- Virginie Orgogozo
- CNRS, UMR 7592, Institut Jacques Monod, Université Paris DiderotParis, France
| | - Baptiste Morizot
- Aix Marseille Université, CNRS, CEPERC UMR 7304Aix en Provence, France
| | - Arnaud Martin
- Department of Molecular Cell Biology, University of CaliforniaBerkeley, CA, USA
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