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Ferree PM, Blagojević J, Houben A, Martins C, Trifonov VA, Vujošević M. What is a B chromosome? Early definitions revisited. G3 (BETHESDA, MD.) 2024; 14:jkae068. [PMID: 38626314 DOI: 10.1093/g3journal/jkae068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Accepted: 03/19/2024] [Indexed: 04/18/2024]
Abstract
Since the discovery of B chromosomes, multiple different definitions of these selfish genetic elements have been put forth. We reconsidered early definitions in light of recently published studies. While there are many characteristics that vary among different B chromosomes, such as their evolutionary origins, size, segregation behaviors, gene content, and function, there is one defining trait of all B chromosomes: they are nonessential for the organism. The points raised here may be useful for framing future B chromosome studies and help guide the categorization of new chromosomal elements that are uncovered in genomic studies.
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Affiliation(s)
- Patrick M Ferree
- Department of Natural Sciences, Pitzer College, Scripps College, Claremont, CA 91711, USA
| | - Jelena Blagojević
- Institute for Biological Research "Siniša Stanković" - National Institute for the Republic of Serbia, University of Belgrade, Belgrade 11060, Serbia
| | - Andreas Houben
- Department of Cytogenetics and Genome Analysis, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Seeland 06466, Germany
| | - Cesar Martins
- Institute of Bioscience at Botucatu, São Paulo State University (UNESP), Botucatu, SP 18618-689, Brazil
| | - Vladimir A Trifonov
- Research Institute for Limnology, University of Innsbruck, Mondsee A-5310, Austria
| | - Mladen Vujošević
- Institute for Biological Research "Siniša Stanković" - National Institute for the Republic of Serbia, University of Belgrade, Belgrade 11060, Serbia
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2
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Coelho MA, David-Palma M, Shea T, Bowers K, McGinley-Smith S, Mohammad AW, Gnirke A, Yurkov AM, Nowrousian M, Sun S, Cuomo CA, Heitman J. Comparative genomics of the closely related fungal genera Cryptococcus and Kwoniella reveals karyotype dynamics and suggests evolutionary mechanisms of pathogenesis. PLoS Biol 2024; 22:e3002682. [PMID: 38843310 DOI: 10.1371/journal.pbio.3002682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 06/18/2024] [Accepted: 05/17/2024] [Indexed: 06/19/2024] Open
Abstract
In exploring the evolutionary trajectories of both pathogenesis and karyotype dynamics in fungi, we conducted a large-scale comparative genomic analysis spanning the Cryptococcus genus, encompassing both global human fungal pathogens and nonpathogenic species, and related species from the sister genus Kwoniella. Chromosome-level genome assemblies were generated for multiple species, covering virtually all known diversity within these genera. Although Cryptococcus and Kwoniella have comparable genome sizes (about 19.2 and 22.9 Mb) and similar gene content, hinting at preadaptive pathogenic potential, our analysis found evidence of gene gain (via horizontal gene transfer) and gene loss in pathogenic Cryptococcus species, which might represent evolutionary signatures of pathogenic development. Genome analysis also revealed a significant variation in chromosome number and structure between the 2 genera. By combining synteny analysis and experimental centromere validation, we found that most Cryptococcus species have 14 chromosomes, whereas most Kwoniella species have fewer (11, 8, 5, or even as few as 3). Reduced chromosome number in Kwoniella is associated with formation of giant chromosomes (up to 18 Mb) through repeated chromosome fusion events, each marked by a pericentric inversion and centromere loss. While similar chromosome inversion-fusion patterns were observed in all Kwoniella species with fewer than 14 chromosomes, no such pattern was detected in Cryptococcus. Instead, Cryptococcus species with less than 14 chromosomes showed reductions primarily through rearrangements associated with the loss of repeat-rich centromeres. Additionally, Cryptococcus genomes exhibited frequent interchromosomal translocations, including intercentromeric recombination facilitated by transposons shared between centromeres. Overall, our findings advance our understanding of genetic changes possibly associated with pathogenicity in Cryptococcus and provide a foundation to elucidate mechanisms of centromere loss and chromosome fusion driving distinct karyotypes in closely related fungal species, including prominent global human pathogens.
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Affiliation(s)
- Marco A Coelho
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Márcia David-Palma
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Terrance Shea
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Katharine Bowers
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Sage McGinley-Smith
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Arman W Mohammad
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Andreas Gnirke
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Andrey M Yurkov
- Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Minou Nowrousian
- Lehrstuhl für Molekulare und Zelluläre Botanik, Ruhr-Universität Bochum, Bochum, Germany
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Christina A Cuomo
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
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Habig M, Grasse AV, Müller J, Stukenbrock EH, Leitner H, Cremer S. Frequent horizontal chromosome transfer between asexual fungal insect pathogens. Proc Natl Acad Sci U S A 2024; 121:e2316284121. [PMID: 38442176 PMCID: PMC10945790 DOI: 10.1073/pnas.2316284121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/24/2024] [Indexed: 03/07/2024] Open
Abstract
Entire chromosomes are typically only transmitted vertically from one generation to the next. The horizontal transfer of such chromosomes has long been considered improbable, yet gained recent support in several pathogenic fungi where it may affect the fitness or host specificity. To date, it is unknown how these transfers occur, how common they are, and whether they can occur between different species. In this study, we show multiple independent instances of horizontal transfers of the same accessory chromosome between two distinct strains of the asexual entomopathogenic fungus Metarhizium robertsii during experimental co-infection of its insect host, the Argentine ant. Notably, only the one chromosome-but no other-was transferred from the donor to the recipient strain. The recipient strain, now harboring the accessory chromosome, exhibited a competitive advantage under certain host conditions. By phylogenetic analysis, we further demonstrate that the same accessory chromosome was horizontally transferred in a natural environment between M. robertsii and another congeneric insect pathogen, Metarhizium guizhouense. Hence, horizontal chromosome transfer is not limited to the observed frequent events within species during experimental infections but also occurs naturally across species. The accessory chromosome that was transferred contains genes that may be involved in its preferential horizontal transfer or support its establishment. These genes encode putative histones and histone-modifying enzymes, as well as putative virulence factors. Our study reveals that both intra- and interspecies horizontal transfer of entire chromosomes is more frequent than previously assumed, likely representing a not uncommon mechanism for gene exchange.
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Affiliation(s)
- Michael Habig
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel24118, Germany
- Max Planck Institute for Evolutionary Biology, Plön24306, Germany
| | - Anna V. Grasse
- Institute of Science and Technology Austria (ISTA), Klosterneuburg3400, Austria
| | - Judith Müller
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel24118, Germany
- Max Planck Institute for Evolutionary Biology, Plön24306, Germany
| | - Eva H. Stukenbrock
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel24118, Germany
- Max Planck Institute for Evolutionary Biology, Plön24306, Germany
| | - Hanna Leitner
- Institute of Science and Technology Austria (ISTA), Klosterneuburg3400, Austria
| | - Sylvia Cremer
- Institute of Science and Technology Austria (ISTA), Klosterneuburg3400, Austria
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4
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Coelho MA, David-Palma M, Shea T, Bowers K, McGinley-Smith S, Mohammad AW, Gnirke A, Yurkov AM, Nowrousian M, Sun S, Cuomo CA, Heitman J. Comparative genomics of Cryptococcus and Kwoniella reveals pathogenesis evolution and contrasting karyotype dynamics via intercentromeric recombination or chromosome fusion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.27.573464. [PMID: 38234769 PMCID: PMC10793447 DOI: 10.1101/2023.12.27.573464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
A large-scale comparative genomic analysis was conducted for the global human fungal pathogens within the Cryptococcus genus, compared to non-pathogenic Cryptococcus species, and related species from the sister genus Kwoniella. Chromosome-level genome assemblies were generated for multiple species of both genera, resulting in a dataset encompassing virtually all of their known diversity. Although Cryptococcus and Kwoniella have comparable genome sizes (about 19.2 and 22.9 Mb) and similar gene content, hinting at pre-adaptive pathogenic potential, our analysis found evidence in pathogenic Cryptococcus species of specific examples of gene gain (via horizontal gene transfer) and gene loss, which might represent evolutionary signatures of pathogenic development. Genome analysis also revealed a significant variation in chromosome number and structure between the two genera. By combining synteny analysis and experimental centromere validation, we found that most Cryptococcus species have 14 chromosomes, whereas most Kwoniella species have fewer (11, 8, 5 or even as few as 3). Reduced chromosome number in Kwoniella is associated with formation of giant chromosomes (up to 18 Mb) through repeated chromosome fusion events, each marked by a pericentric inversion and centromere loss. While similar chromosome inversion-fusion patterns were observed in all Kwoniella species with fewer than 14 chromosomes, no such pattern was detected in Cryptococcus. Instead, Cryptococcus species with less than 14 chromosomes, underwent chromosome reductions primarily through rearrangements associated with the loss of repeat-rich centromeres. Additionally, Cryptococcus genomes exhibited frequent interchromosomal translocations, including intercentromeric recombination facilitated by transposons shared between centromeres. Taken together, our findings advance our understanding of genomic changes possibly associated with pathogenicity in Cryptococcus and provide a foundation to elucidate mechanisms of centromere loss and chromosome fusion driving distinct karyotypes in closely related fungal species, including prominent global human pathogens.
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Affiliation(s)
- Marco A. Coelho
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Márcia David-Palma
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Terrance Shea
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Katharine Bowers
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | | | | | - Andreas Gnirke
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Andrey M. Yurkov
- Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Minou Nowrousian
- Lehrstuhl für Molekulare und Zelluläre Botanik, Ruhr-Universität Bochum, Bochum, Germany
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
| | | | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
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Deng Y, Guo L, Lin L, Li Y, Zhang J, Zhang Y, Yuan B, Ke L, Xie B, Ming R. Meiosis in an asymmetric dikaryotic genome of Tremella fuciformis Tr01 facilitates new chromosome formation. Genome Biol 2023; 24:280. [PMID: 38053144 PMCID: PMC10696834 DOI: 10.1186/s13059-023-03093-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 10/22/2023] [Indexed: 12/07/2023] Open
Abstract
BACKGROUND The dikaryotic stage dominates most of the life cycle in basidiomycetes, and each cell carries two different haploid nuclei. Accurate phasing of these two nuclear genomes and their interactions have long been of interest. RESULTS We combine PacBio HiFi reads, Nanopore ultra-long reads, and Hi-C data to generate a complete, high-quality asymmetric dikaryotic genome of Tremella fuciformis Tr01, including Haplotypes A and B genomes. We assemble a meiotic haploid DBZ04 genome and detect three recombination events in these two haplotypes. We identify several chromosomal rearrangements that lead to differences in chromosome number, length, content, and sequence arrangement between these two haplotypes. Each nucleus contains a two-speed genome, harboring three accessory chromosomes and two accessory compartments that affect horizontal chromatin transfer between nuclei. We find few basidiospores are ejected from fruiting bodies of Tr01. Most monospore isolates sequenced belong to Tr01-Haplotype A genome architecture. More than one-third of monospore isolates carry one or two extra chromosomes including Chr12B and two new chromosomes ChrN1 and ChrN2. We hypothesize that homologous regions of seven sister chromatids pair into a large complex during meiosis, followed by inter-chromosomal recombination at physical contact sites and formation of new chromosomes. CONCLUSION We assemble two haplotype genomes of T. fuciformis Tr01 and provide the first overview of basidiomycetous genomes with discrete genomic architecture. Meiotic activities of asymmetric dikaryotic genomes result in formation of new chromosomes, aneuploidy of some daughter cells, and inviability of most other daughter cells. We propose a new approach for breeding of sporeless mushroom.
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Affiliation(s)
- Youjin Deng
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
- Center for Genomics, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Lin Guo
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
- Center for Genomics, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Longji Lin
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
- Center for Genomics, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Yuefeng Li
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Jinxiang Zhang
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Yue Zhang
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Bin Yuan
- Zhangzhou Institute of Agricultural Science, Zhangzhou, Fujian, 363005, China
| | - Lina Ke
- Zhangzhou Institute of Agricultural Science, Zhangzhou, Fujian, 363005, China
| | - Baogui Xie
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China.
| | - Ray Ming
- Center for Genomics, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China.
- Department of Plant Biology, University of Illinois at Urbana-Champaign, 1201 W. Gregory Drive, Urbana, IL, 61801, USA.
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6
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Ebrahimzadegan R, Fuchs J, Chen J, Schubert V, Meister A, Houben A, Mirzaghaderi G. Meiotic segregation and post-meiotic drive of the Festuca pratensis B chromosome. Chromosome Res 2023; 31:26. [PMID: 37658970 PMCID: PMC10474989 DOI: 10.1007/s10577-023-09728-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 07/13/2023] [Accepted: 07/19/2023] [Indexed: 09/05/2023]
Abstract
In many species, the transmission of B chromosomes (Bs) does not follow the Mendelian laws of equal segregation and independent assortment. This deviation results in transmission rates of Bs higher than 0.5, a process known as "chromosome drive". Here, we studied the behavior of the 103 Mbp-large B chromosome of Festuca pratensis during all meiotic and mitotic stages of microsporogenesis. Mostly, the B chromosome of F. pratensis segregates during meiosis like standard A chromosomes (As). In some cases, the B passes through meiosis in a non-Mendelian segregation leading to their accumulation already in meiosis. However, a true drive of the B happens during the first pollen mitosis, by which the B preferentially migrates to the generative nucleus. During second pollen mitosis, B divides equally between the two sperms. Despite some differences in the frequency of drive between individuals with different numbers of Bs, at least 82% of drive was observed. Flow cytometry-based quantification of B-containing sperm nuclei agrees with the FISH data.
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Affiliation(s)
- Rahman Ebrahimzadegan
- Department of Plant Production and Genetics, Faculty of Agriculture, University of Kurdistan, Sanandaj, 66177-15175, Iran
| | - Jörg Fuchs
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
| | - Jianyong Chen
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
| | - Veit Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
| | - Armin Meister
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Seeland, Germany.
| | - Ghader Mirzaghaderi
- Department of Plant Production and Genetics, Faculty of Agriculture, University of Kurdistan, Sanandaj, 66177-15175, Iran.
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Rajpal VR, Sharma S, Sehgal D, Sharma P, Wadhwa N, Dhakate P, Chandra A, Thakur RK, Deb S, Rama Rao S, Mir BA, Raina SN. Comprehending the dynamism of B chromosomes in their journey towards becoming unselfish. Front Cell Dev Biol 2023; 10:1072716. [PMID: 36684438 PMCID: PMC9846793 DOI: 10.3389/fcell.2022.1072716] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/13/2022] [Indexed: 01/06/2023] Open
Abstract
Investigated for more than a century now, B chromosomes (Bs) research has come a long way from Bs being considered parasitic or neutral to becoming unselfish and bringing benefits to their hosts. B chromosomes exist as accessory chromosomes along with the standard A chromosomes (As) across eukaryotic taxa. Represented singly or in multiple copies, B chromosomes are largely heterochromatic but also contain euchromatic and organellar segments. Although B chromosomes are derived entities, they follow their species-specific evolutionary pattern. B chromosomes fail to pair with the standard chromosomes during meiosis and vary in their number, size, composition and structure across taxa and ensure their successful transmission through non-mendelian mechanisms like mitotic, pre-meiotic, meiotic or post-meiotic drives, unique non-disjunction, self-pairing or even imparting benefits to the host when they lack drive. B chromosomes have been associated with cellular processes like sex determination, pathogenicity, resistance to pathogens, phenotypic effects, and differential gene expression. With the advancements in B-omics research, novel insights have been gleaned on their functions, some of which have been associated with the regulation of gene expression of A chromosomes through increased expression of miRNAs or differential expression of transposable elements located on them. The next-generation sequencing and emerging technologies will further likely unravel the cellular, molecular and functional behaviour of these enigmatic entities. Amidst the extensive fluidity shown by B chromosomes in their structural and functional attributes, we perceive that the existence and survival of B chromosomes in the populations most likely seem to be a trade-off between the drive efficiency and adaptive significance versus their adverse effects on reproduction.
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Affiliation(s)
- Vijay Rani Rajpal
- Department of Botany, Hansraj College, University of Delhi, Delhi, India,*Correspondence: Vijay Rani Rajpal, , ; Soom Nath Raina,
| | - Suman Sharma
- Department of Botany, Ramjas College, University of Delhi, Delhi, India
| | - Deepmala Sehgal
- Syngenta, International Maize and Wheat Improvement Center (CIMMYT), Texcoco, Mexico
| | - Prashansa Sharma
- Department of Botany, Hansraj College, University of Delhi, Delhi, India
| | - Nikita Wadhwa
- University School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi, India
| | | | - Atika Chandra
- Department of Botany, Maitreyi College, University of Delhi, New Delhi, India
| | - Rakesh Kr. Thakur
- Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, India
| | - Sohini Deb
- Department of Biotechnology and Bioinformatics, North Eastern Hill University, Shillong, Meghalaya, India
| | - Satyawada Rama Rao
- Department of Biotechnology and Bioinformatics, North Eastern Hill University, Shillong, Meghalaya, India
| | - Bilal Ahmad Mir
- Department of Botany, University of Kashmir, Srinagar, India
| | - Soom Nath Raina
- Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, India,*Correspondence: Vijay Rani Rajpal, , ; Soom Nath Raina,
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