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Reddy PS, Dhaware MG, Sivasakthi K, Divya K, Nagaraju M, Sri Cindhuri K, Kavi Kishor PB, Bhatnagar-Mathur P, Vadez V, Sharma KK. Pearl Millet Aquaporin Gene PgPIP2;6 Improves Abiotic Stress Tolerance in Transgenic Tobacco. FRONTIERS IN PLANT SCIENCE 2022; 13:820996. [PMID: 35356115 PMCID: PMC8959815 DOI: 10.3389/fpls.2022.820996] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 01/13/2022] [Indexed: 05/24/2023]
Abstract
Pearl millet [Pennisetum glaucum (L) R. Br.] is an important cereal crop of the semiarid tropics, which can withstand prolonged drought and heat stress. Considering an active involvement of the aquaporin (AQP) genes in water transport and desiccation tolerance besides several basic functions, their potential role in abiotic stress tolerance was systematically characterized and functionally validated. A total of 34 AQP genes from P. glaucum were identified and categorized into four subfamilies, viz., plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), nodulin-26-like intrinsic proteins (NIPs), and small basic intrinsic proteins (SIPs). Sequence analysis revealed that PgAQPs have conserved characters of AQP genes with a closer relationship to sorghum. The PgAQPs were expressed differentially under high vapor pressure deficit (VPD) and progressive drought stresses where the PgPIP2;6 gene showed significant expression under high VPD and drought stress. Transgenic tobacco plants were developed by heterologous expression of the PgPIP2;6 gene and functionally characterized under different abiotic stresses to further unravel their role. Transgenic tobacco plants in the T2 generations displayed restricted transpiration and low root exudation rates in low- and high-VPD conditions. Under progressive drought stress, wild-type (WT) plants showed a quick or faster decline of soil moisture than transgenics. While under heat stress, PgPIP2;6 transgenics showed better adaptation to heat (40°C) with high canopy temperature depression (CTD) and low transpiration; under low-temperature stress, they displayed lower transpiration than their non-transgenic counterparts. Cumulatively, lower transpiration rate (Tr), low root exudation rate, declined transpiration, elevated CTD, and lower transpiration indicate that PgPIP2;6 plays a role under abiotic stress tolerance. Since the PgPIP2;6 transgenic plants exhibited better adaptation against major abiotic stresses such as drought, high VPD, heat, and cold stresses by virtue of enhanced transpiration efficiency, it has the potential to engineer abiotic stress tolerance for sustained growth and productivity of crops.
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Affiliation(s)
| | - Mahamaya G. Dhaware
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India
| | - Kaliamoorthy Sivasakthi
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India
| | - Kummari Divya
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India
| | - Marka Nagaraju
- Department of Biochemistry, ICMR – National Institute of Nutrition, Hyderabad, India
| | - Katamreddy Sri Cindhuri
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India
| | - Polavarapu Bilhan Kavi Kishor
- Department of Biotechnology, Vignan’s Foundation for Science, Technology & Research (Deemed to be University), Vadlamudi, India
| | - Pooja Bhatnagar-Mathur
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India
| | - Vincent Vadez
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India
| | - Kiran K. Sharma
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India
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Abstract
The number of complete genome sequences explodes more and more with each passing year. Thus, methods for genome annotation need to be honed constantly to handle the deluge of information. Annotation of pseudogenes (i.e., gene copies that appear not to make a functional protein) in genomes is a persistent problem; here, we overview pseudogene annotation methods that are based on the detection of sequence homology in genomic DNA.
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Affiliation(s)
- Paul M Harrison
- Department of Biology, McGill University, Montreal, QC, Canada.
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Origin and Evolution of Two Independently Duplicated Genes Encoding UDP- Glucose: Glycoprotein Glucosyltransferases in Caenorhabditis and Vertebrates. G3-GENES GENOMES GENETICS 2020; 10:755-768. [PMID: 31796523 PMCID: PMC7003075 DOI: 10.1534/g3.119.400868] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
UDP- glucose: glycoprotein glucosyltransferase (UGGT) is a protein that operates as the gatekeeper for the endoplasmic reticulum (ER) quality control mechanism of glycoprotein folding. It is known that vertebrates and Caenorhabditis genomes harbor two uggt gene copies that exhibit differences in their properties. Bayesian phylogenetic inference based on 195 UGGT and UGGT-like protein sequences of an ample spectrum of eukaryotic species showed that uggt genes went through independent duplications in Caenorhabditis and vertebrates. In both lineages, the catalytic domain of the duplicated genes was subjected to a strong purifying selective pressure, while the recognition domain was subjected to episodic positive diversifying selection. Selective relaxation in the recognition domain was more pronounced in Caenorhabditis uggt-b than in vertebrates uggt-2. Structural bioinformatics analysis revealed that Caenorhabditis UGGT-b protein lacks essential sequences proposed to be involved in the recognition of unfolded proteins. When we assayed glucosyltrasferase activity of a chimeric protein composed by Caenorhabditis uggt-b recognition domain fused to S. pombe catalytic domain expressed in yeast, no activity was detected. The present results support the conservation of the UGGT activity in the catalytic domain and a putative divergent function of the recognition domain for the UGGT2 protein in vertebrates, which would have gone through a specialization process. In Caenorhabditis, uggt-b evolved under different constraints compared to uggt-a which, by means of a putative neofunctionalization process, resulted in a non-redundant paralog. The non-canonical function of uggt-b in the worm lineage highlights the need to take precautions before generalizing gene functions in model organisms.
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Extracellular RNA in a single droplet of human serum reflects physiologic and disease states. Proc Natl Acad Sci U S A 2019; 116:19200-19208. [PMID: 31481608 PMCID: PMC6754586 DOI: 10.1073/pnas.1908252116] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Extracellular RNAs (exRNAs) are present in human serum. It remains unclear to what extent these circulating exRNAs may reflect human physiologic and disease states. Here, we developed SILVER-seq (Small Input Liquid Volume Extracellular RNA Sequencing) to efficiently sequence both integral and fragmented exRNAs from a small droplet (5 μL to 7 μL) of liquid biopsy. We calibrated SILVER-seq in reference to other RNA sequencing methods based on milliliters of input serum and quantified droplet-to-droplet and donor-to-donor variations. We carried out SILVER-seq on more than 150 serum droplets from male and female donors ranging from 18 y to 48 y of age. SILVER-seq detected exRNAs from more than a quarter of the human genes, including small RNAs and fragments of mRNAs and long noncoding RNAs (lncRNAs). The detected exRNAs included those derived from genes with tissue (e.g., brain)-specific expression. The exRNA expression levels separated the male and female samples and were correlated with chronological age. Noncancer and breast cancer donors exhibited pronounced differences, whereas donors with or without cancer recurrence exhibited moderate differences in exRNA expression patterns. Even without using differentially expressed exRNAs as features, nearly all cancer and noncancer samples and a large portion of the recurrence and nonrecurrence samples could be correctly classified by exRNA expression values. These data suggest the potential of using exRNAs in a single droplet of serum for liquid biopsy-based diagnostics.
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Seeling JM, Farmer AA, Mansfield A, Cho H, Choudhary M. Differential Selective Pressures Experienced by the Aurora Kinase Gene Family. Int J Mol Sci 2017; 19:ijms19010072. [PMID: 29283376 PMCID: PMC5796022 DOI: 10.3390/ijms19010072] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/22/2017] [Accepted: 12/23/2017] [Indexed: 12/31/2022] Open
Abstract
Aurora kinases (AKs) are serine/threonine kinases that are essential for cell division. Humans have three AK genes: AKA, AKB, and AKC. AKA is required for centrosome assembly, centrosome separation, and bipolar spindle assembly, and its mutation leads to abnormal spindle morphology. AKB is required for the spindle checkpoint and proper cytokinesis, and mutations cause chromosome misalignment and cytokinesis failure. AKC is expressed in germ cells, and has a role in meiosis analogous to that of AKB in mitosis. Mutation of any of the three isoforms can lead to cancer. AK proteins possess divergent N- and C-termini and a conserved central catalytic domain. We examined the evolution of the AK gene family using an identity matrix and by building a phylogenetic tree. The data suggest that AKA is the vertebrate ancestral gene, and that AKB and AKC resulted from gene duplication in placental mammals. In a nonsynonymous/synonymous rate substitution analysis, we found that AKB experienced the strongest, and AKC the weakest, purifying selection. Both the N- and C-termini and regions within the kinase domain experienced differential selection among the AK isoforms. These differentially selected sequences may be important for species specificity and isoform specificity, and are therefore potential therapeutic targets.
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Affiliation(s)
- Joni M Seeling
- Department of Biology, Lone Star College, Woodlands, TX 77375, USA.
| | - Alexis A Farmer
- Department of Biological Sciences, Sam Houston State University, Huntsville, TX 77341, USA.
| | - Adam Mansfield
- Department of Computer Science, Sam Houston State University, Huntsville, TX 77341, USA.
| | - Hyuk Cho
- Department of Computer Science, Sam Houston State University, Huntsville, TX 77341, USA.
| | - Madhusudan Choudhary
- Department of Biological Sciences, Sam Houston State University, Huntsville, TX 77341, USA.
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Casola C, Betrán E. The Genomic Impact of Gene Retrocopies: What Have We Learned from Comparative Genomics, Population Genomics, and Transcriptomic Analyses? Genome Biol Evol 2017; 9:1351-1373. [PMID: 28605529 PMCID: PMC5470649 DOI: 10.1093/gbe/evx081] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2017] [Indexed: 02/07/2023] Open
Abstract
Gene duplication is a major driver of organismal evolution. Gene retroposition is a mechanism of gene duplication whereby a gene's transcript is used as a template to generate retroposed gene copies, or retrocopies. Intriguingly, the formation of retrocopies depends upon the enzymatic machinery encoded by retrotransposable elements, genomic parasites occurring in the majority of eukaryotes. Most retrocopies are depleted of the regulatory regions found upstream of their parental genes; therefore, they were initially considered transcriptionally incompetent gene copies, or retropseudogenes. However, examples of functional retrocopies, or retrogenes, have accumulated since the 1980s. Here, we review what we have learned about retrocopies in animals, plants and other eukaryotic organisms, with a particular emphasis on comparative and population genomic analyses complemented with transcriptomic datasets. In addition, these data have provided information about the dynamics of the different "life cycle" stages of retrocopies (i.e., polymorphic retrocopy number variants, fixed retropseudogenes and retrogenes) and have provided key insights into the retroduplication mechanisms, the patterns and evolutionary forces at work during the fixation process and the biological function of retrogenes. Functional genomic and transcriptomic data have also revealed that many retropseudogenes are transcriptionally active and a biological role has been experimentally determined for many. Finally, we have learned that not only non-long terminal repeat retroelements but also long terminal repeat retroelements play a role in the emergence of retrocopies across eukaryotes. This body of work has shown that mRNA-mediated duplication represents a widespread phenomenon that produces an array of new genes that contribute to organismal diversity and adaptation.
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Affiliation(s)
- Claudio Casola
- Department of Ecosystem Science and Management, Texas A&M University, TX
| | - Esther Betrán
- Department of Biology, University of Texas at Arlington, Arlington, TX
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Xiao J, Sekhwal MK, Li P, Ragupathy R, Cloutier S, Wang X, You FM. Pseudogenes and Their Genome-Wide Prediction in Plants. Int J Mol Sci 2016; 17:E1991. [PMID: 27916797 PMCID: PMC5187791 DOI: 10.3390/ijms17121991] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 11/20/2016] [Accepted: 11/22/2016] [Indexed: 11/17/2022] Open
Abstract
Pseudogenes are paralogs generated from ancestral functional genes (parents) during genome evolution, which contain critical defects in their sequences, such as lacking a promoter, having a premature stop codon or frameshift mutations. Generally, pseudogenes are functionless, but recent evidence demonstrates that some of them have potential roles in regulation. The majority of pseudogenes are generated from functional progenitor genes either by gene duplication (duplicated pseudogenes) or retro-transposition (processed pseudogenes). Pseudogenes are primarily identified by comparison to their parent genes. Bioinformatics tools for pseudogene prediction have been developed, among which PseudoPipe, PSF and Shiu's pipeline are publicly available. We compared these three tools using the well-annotated Arabidopsis thaliana genome and its known 924 pseudogenes as a test data set. PseudoPipe and Shiu's pipeline identified ~80% of A. thaliana pseudogenes, of which 94% were shared, while PSF failed to generate adequate results. A need for improvement of the bioinformatics tools for pseudogene prediction accuracy in plant genomes was thus identified, with the ultimate goal of improving the quality of genome annotation in plants.
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Affiliation(s)
- Jin Xiao
- Morden Research and Development Centre, Agriculture and Agri-Food Canada, Morden, MB R6M 1Y5, Canada.
- Department of Agronomy, Nanjing Agricultural University, Nanjing 210095, China.
| | - Manoj Kumar Sekhwal
- Morden Research and Development Centre, Agriculture and Agri-Food Canada, Morden, MB R6M 1Y5, Canada.
- Department of Soil Science, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
| | - Pingchuan Li
- Morden Research and Development Centre, Agriculture and Agri-Food Canada, Morden, MB R6M 1Y5, Canada.
| | - Raja Ragupathy
- Department of Plant Science, University of Saskatchewan, Saskatoon, SK S7N 5A2, Canada.
| | - Sylvie Cloutier
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, ON K1A 0C6, Canada.
| | - Xiue Wang
- Department of Agronomy, Nanjing Agricultural University, Nanjing 210095, China.
| | - Frank M You
- Morden Research and Development Centre, Agriculture and Agri-Food Canada, Morden, MB R6M 1Y5, Canada.
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de Las Heras-Rubio A, Perucho L, Paciucci R, Vilardell J, LLeonart ME. Ribosomal proteins as novel players in tumorigenesis. Cancer Metastasis Rev 2015; 33:115-41. [PMID: 24375388 DOI: 10.1007/s10555-013-9460-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ribosome biogenesis is the most demanding energetic and metabolic expenditure of the cell. The nucleolus, a nuclear compartment, coordinates rRNA transcription, maturation, and assembly into ribosome subunits. The transcription process is highly coordinated with ribosome biogenesis. In this context, ribosomal proteins (RPs) play a crucial role. In the last decade, an increasing number of studies have associated RPs with extraribosomal functions related to proliferation. Importantly, the expression of RPs appears to be deregulated in several human disorders due, at least in part, to genetic mutations. Although the deregulation of RPs in human malignancies is commonly observed, a more complex mechanism is believed to be involved, favoring the tumorigenic process, its progression and metastasis. This review explores the roles of the most frequently mutated oncogenes and tumor suppressor genes in human cancer that modulate ribosome biogenesis, including their interaction with RPs. In this regard, we propose a new focus for novel therapies.
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Affiliation(s)
- A de Las Heras-Rubio
- Oncology and Pathology Group, Institut de Recerca Hospital Vall d'Hebron, Passeig Vall d'Hebron 119-129, 08035, Barcelona, Spain
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Makunin AI, Dementyeva PV, Graphodatsky AS, Volobouev VT, Kukekova AV, Trifonov VA. Genes on B chromosomes of vertebrates. Mol Cytogenet 2014; 7:99. [PMID: 25538793 PMCID: PMC4274688 DOI: 10.1186/s13039-014-0099-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 12/05/2014] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND There is a growing body of evidence that B chromosomes, once regarded as totally heterochromatic and genetically inert, harbor multiple segmental duplications containing clusters of ribosomal RNA genes, processed pseudogenes and protein-coding genes. Application of novel molecular approaches further supports complex composition and possible phenotypic effects of B chromosomes. RESULTS Here we review recent findings of gene-carrying genomic segments on B chromosomes from different vertebrate groups. We demonstrate that the genetic content of B chromosomes is highly heterogeneous and some B chromosomes contain multiple large duplications derived from various chromosomes of the standard karyotype. Although B chromosomes seem to be mostly homologous to each other within a species, their genetic content differs between species. There are indications that some genomic regions are more likely to be located on B chromosomes. CONCLUSIONS The discovery of multiple autosomal genes on B chromosomes opens a new discussion about their possible effects ranging from sex determination to fitness and adaptation, their complex interactions with host genome and role in evolution.
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Affiliation(s)
- Alexey I Makunin
- />Institute of Molecular and Cellular Biology SВ RAS, Novosibirsk, 630090 Russia
- />Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg, Russia
| | - Polina V Dementyeva
- />Institute of Molecular and Cellular Biology SВ RAS, Novosibirsk, 630090 Russia
| | - Alexander S Graphodatsky
- />Institute of Molecular and Cellular Biology SВ RAS, Novosibirsk, 630090 Russia
- />Novosibirsk State University, Novosibirsk, Russia
| | - Vitaly T Volobouev
- />Museum National d’Histoire Naturelle, Origine, Structure et Evolution de la Biodiversite, Paris, France
| | - Anna V Kukekova
- />Department of Animal Sciences, The University of Illinois at Urbana-Champaign, Champaign, USA
| | - Vladimir A Trifonov
- />Institute of Molecular and Cellular Biology SВ RAS, Novosibirsk, 630090 Russia
- />Novosibirsk State University, Novosibirsk, Russia
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Abstract
The number of complete genome sequences explodes more and more with each passing year. Thus, methods for genome annotation need to be honed constantly to handle the deluge of information. Annotation of pseudogenes (i.e., gene copies that appear not to make a functional protein) in genomes is a persistent problem; here, we overview pseudogene annotation methods that are based on the detection of sequence homology in genomic DNA.
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Affiliation(s)
- Paul M Harrison
- Department of Biology, McGill University, Stewart Biology Building, 1205 Doctor Penfield Avenue, Montreal, QC, Canada, H3A 1B1,
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Peters AE, Bavishi A, Cho H, Choudhary M. Evolutionary constraints and expression analysis of gene duplications in Rhodobacter sphaeroides 2.4.1. BMC Res Notes 2012; 5:192. [PMID: 22533893 PMCID: PMC3494609 DOI: 10.1186/1756-0500-5-192] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Accepted: 04/05/2012] [Indexed: 01/07/2023] Open
Abstract
Background Gene duplication is a major force that contributes to the evolution of new metabolic functions in all organisms. Rhodobacter sphaeroides 2.4.1 is a bacterium that displays a wide degree of metabolic versatility and genome complexity and therefore is a fitting model for the study of gene duplications in bacteria. A comprehensive analysis of 234 duplicate gene-pairs in R. sphaeroides was performed using structural constraint and expression analysis. Results The results revealed that most gene-pairs in in-paralogs are maintained under negative selection (ω ≤ 0.3), but the strength of selection differed among in-paralog gene-pairs. Although in-paralogs located on different replicons are maintained under purifying selection, the duplicated genes distributed between the primary chromosome (CI) and the second chromosome (CII) are relatively less selectively constrained than the gene-pairs located within each chromosome. The mRNA expression patterns of duplicate gene-pairs were examined through microarray analysis of this organism grown under seven different growth conditions. Results revealed that ~62% of paralogs have similar expression patterns (cosine ≥ 0.90) over all of these growth conditions, while only ~7% of paralogs are very different in their expression patterns (cosine < 0.50). Conclusions The overall findings of the study suggest that only a small proportion of paralogs contribute to the metabolic diversity and the evolution of novel metabolic functions in R. sphaeroides. In addition, the lack of relationships between structural constraints and gene-pair expression suggests that patterns of gene-pair expression are likely associated with conservation or divergence of gene-pair promoter regions and other coregulation mechanisms.
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Affiliation(s)
- Anne E Peters
- Department of Biological Sciences, Sam Houston State University, Huntsville, TX 77341, USA
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12
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Ponting CP, Nellåker C, Meader S. Rapid turnover of functional sequence in human and other genomes. Annu Rev Genomics Hum Genet 2011; 12:275-99. [PMID: 21721940 DOI: 10.1146/annurev-genom-090810-183115] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The amount of a genome's sequence that is functional has been surprisingly difficult to estimate accurately. This has severely hindered analyses asking whether the amount of functional genomic sequence correlates with organismal complexity. Most studies estimate these amounts by considering nucleotide substitution rates within aligned sequences. These approaches show reduced power to identify sequence that is aligned, functional, and constrained only within narrowly defined phyla. The neutral indel model exploits insertions or deletions (indels) rather than substitutions in predicting functional sequence. Surprisingly, this method indicates that half of all functional sequence is specific to individual eutherian lineages. This review considers the rates at which coding or noncoding and functional or nonfunctional sequence changes among mammalian genomes. In contrast to the slow rate at which protein-coding sequence changes, functional noncoding sequence appears to change or be turned over at rapid rates in mammals.
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Affiliation(s)
- Chris P Ponting
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, United Kingdom.
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Ho MR, Tsai KW, Chen CH, Lin WC. dbDNV: a resource of duplicated gene nucleotide variants in human genome. Nucleic Acids Res 2010; 39:D920-5. [PMID: 21097891 PMCID: PMC3013738 DOI: 10.1093/nar/gkq1197] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Gene duplications are scattered widely throughout the human genome. A single-base difference located in nearly identical duplicated segments may be misjudged as a single nucleotide polymorphism (SNP) from individuals. This imperfection is undistinguishable in current genotyping methods. As the next-generation sequencing technologies become more popular for sequence-based association studies, numerous ambiguous SNPs are rapidly accumulated. Thus, analyzing duplication variations in the reference genome to assist in preventing false positive SNPs is imperative. We have identified >10% of human genes associated with duplicated gene loci (DGL). Through meticulous sequence alignments of DGL, we systematically designated 1 236 956 variations as duplicated gene nucleotide variants (DNVs). The DNV database (dbDNV) (http://goods.ibms.sinica.edu.tw/DNVs/) has been established to promote more accurate variation annotation. Aside from the flat file download, users can explore the gene-related duplications and the associated DNVs by DGL and DNV searches, respectively. In addition, the dbDNV contains 304 110 DNV-coupled SNPs. From DNV-coupled SNP search, users observe which SNP records are also variants among duplicates. This is useful while ∼58% of exonic SNPs in DGL are DNV-coupled. Because of high accumulation of ambiguous SNPs, we suggest that annotating SNPs with DNVs possibilities should improve association studies of these variants with human diseases.
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Affiliation(s)
- Meng-Ru Ho
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei 112, Taiwan
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Molineris I, Sales G, Bianchi F, Di Cunto F, Caselle M. A New Approach for the Identification of Processed Pseudogenes. J Comput Biol 2010; 17:755-65. [DOI: 10.1089/cmb.2009.0027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Affiliation(s)
- Ivan Molineris
- Theoretical Physics Department, Universit di Torino, Torino, Italy
| | - Gabriele Sales
- Theoretical Physics Department, Universit di Torino, Torino, Italy
| | - Federico Bianchi
- Molecular Biotechnology Center, Universit di Torino, Torino, Italy
| | | | - Michele Caselle
- Theoretical Physics Department, Universit di Torino, Torino, Italy
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Balasubramanian S, Zheng D, Liu YJ, Fang G, Frankish A, Carriero N, Robilotto R, Cayting P, Gerstein M. Comparative analysis of processed ribosomal protein pseudogenes in four mammalian genomes. Genome Biol 2009; 10:R2. [PMID: 19123937 PMCID: PMC2687790 DOI: 10.1186/gb-2009-10-1-r2] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 01/05/2009] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The availability of genome sequences of numerous organisms allows comparative study of pseudogenes in syntenic regions. Conservation of pseudogenes suggests that they might have a functional role in some instances. RESULTS We report the first large-scale comparative analysis of ribosomal protein pseudogenes in four mammalian genomes (human, chimpanzee, mouse and rat). To this end, we have assigned these pseudogenes in the four organisms using an automated pipeline and make the results available online. Each organism has a large number of ribosomal protein pseudogenes (approximately 1,400 to 2,800). The majority of them are processed (generated by retrotransposition). However, we do not see a correlation between the number of pseudogenes associated with a ribosomal protein gene and its mRNA abundance. Analysis of pseudogenes in syntenic regions between species shows that most are conserved between human and chimpanzee, but very few are conserved between primates and rodents. Interestingly, syntenic pseudogenes have a lower rate of nucleotide substitution than their surrounding intergenic DNA. Moreover, evidence from expressed sequence tags indicates that two pseudogenes conserved between human and mouse are transcribed. Detailed analysis shows that one of them, the pseudogene of RPS27, is likely to be a protein-coding gene. This is significant as previous reports indicated there are exactly 80 ribosomal protein genes encoded by the human genome. CONCLUSIONS Our analysis indicates that processed ribosomal protein pseudogenes abound in mammalian genomes, but few of these are conserved between primates and rodents. This highlights the large amount of recent retrotranspositional activity in mammals and a relatively larger amount of it in the rodent lineage.
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Baertsch R, Diekhans M, Kent WJ, Haussler D, Brosius J. Retrocopy contributions to the evolution of the human genome. BMC Genomics 2008; 9:466. [PMID: 18842134 PMCID: PMC2584115 DOI: 10.1186/1471-2164-9-466] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Accepted: 10/08/2008] [Indexed: 02/06/2023] Open
Abstract
Background Evolution via point mutations is a relatively slow process and is unlikely to completely explain the differences between primates and other mammals. By contrast, 45% of the human genome is composed of retroposed elements, many of which were inserted in the primate lineage. A subset of retroposed mRNAs (retrocopies) shows strong evidence of expression in primates, often yielding functional retrogenes. Results To identify and analyze the relatively recently evolved retrogenes, we carried out BLASTZ alignments of all human mRNAs against the human genome and scored a set of features indicative of retroposition. Of over 12,000 putative retrocopy-derived genes that arose mainly in the primate lineage, 726 with strong evidence of transcript expression were examined in detail. These mRNA retroposition events fall into three categories: I) 34 retrocopies and antisense retrocopies that added potential protein coding space and UTRs to existing genes; II) 682 complete retrocopy duplications inserted into new loci; and III) an unexpected set of 13 retrocopies that contributed out-of-frame, or antisense sequences in combination with other types of transposed elements (SINEs, LINEs, LTRs), even unannotated sequence to form potentially novel genes with no homologs outside primates. In addition to their presence in human, several of the gene candidates also had potentially viable ORFs in chimpanzee, orangutan, and rhesus macaque, underscoring their potential of function. Conclusion mRNA-derived retrocopies provide raw material for the evolution of genes in a wide variety of ways, duplicating and amending the protein coding region of existing genes as well as generating the potential for new protein coding space, or non-protein coding RNAs, by unexpected contributions out of frame, in reverse orientation, or from previously non-protein coding sequence.
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Affiliation(s)
- Robert Baertsch
- Center for Biomolecular Science and Engineering, University of California Santa Cruz, Santa Cruz, California 95064, USA.
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Comparative genomics search for losses of long-established genes on the human lineage. PLoS Comput Biol 2008; 3:e247. [PMID: 18085818 PMCID: PMC2134963 DOI: 10.1371/journal.pcbi.0030247] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 10/30/2007] [Indexed: 02/01/2023] Open
Abstract
Taking advantage of the complete genome sequences of several mammals, we developed a novel method to detect losses of well-established genes in the human genome through syntenic mapping of gene structures between the human, mouse, and dog genomes. Unlike most previous genomic methods for pseudogene identification, this analysis is able to differentiate losses of well-established genes from pseudogenes formed shortly after segmental duplication or generated via retrotransposition. Therefore, it enables us to find genes that were inactivated long after their birth, which were likely to have evolved nonredundant biological functions before being inactivated. The method was used to look for gene losses along the human lineage during the approximately 75 million years (My) since the common ancestor of primates and rodents (the euarchontoglire crown group). We identified 26 losses of well-established genes in the human genome that were all lost at least 50 My after their birth. Many of them were previously characterized pseudogenes in the human genome, such as GULO and UOX. Our methodology is highly effective at identifying losses of single-copy genes of ancient origin, allowing us to find a few well-known pseudogenes in the human genome missed by previous high-throughput genome-wide studies. In addition to confirming previously known gene losses, we identified 16 previously uncharacterized human pseudogenes that are definitive losses of long-established genes. Among them is ACYL3, an ancient enzyme present in archaea, bacteria, and eukaryotes, but lost approximately 6 to 8 Mya in the ancestor of humans and chimps. Although losses of well-established genes do not equate to adaptive gene losses, they are a useful proxy to use when searching for such genetic changes. This is especially true for adaptive losses that occurred more than 250,000 years ago, since any genetic evidence of the selective sweep indicative of such an event has been erased.
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