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  • 1
    Publication Date: 2013-07-23
    Description: Loss of sexual reproduction is considered an evolutionary dead end for metazoans, but bdelloid rotifers challenge this view as they appear to have persisted asexually for millions of years. Neither male sex organs nor meiosis have ever been observed in these microscopic animals: oocytes are formed through mitotic divisions, with no reduction of chromosome number and no indication of chromosome pairing. However, current evidence does not exclude that they may engage in sex on rare, cryptic occasions. Here we report the genome of a bdelloid rotifer, Adineta vaga (Davis, 1873), and show that its structure is incompatible with conventional meiosis. At gene scale, the genome of A. vaga is tetraploid and comprises both anciently duplicated segments and less divergent allelic regions. However, in contrast to sexual species, the allelic regions are rearranged and sometimes even found on the same chromosome. Such structure does not allow meiotic pairing; instead, we find abundant evidence of gene conversion, which may limit the accumulation of deleterious mutations in the absence of meiosis. Gene families involved in resistance to oxidation, carbohydrate metabolism and defence against transposons are significantly expanded, which may explain why transposable elements cover only 3% of the assembled sequence. Furthermore, 8% of the genes are likely to be of non-metazoan origin and were probably acquired horizontally. This apparent convergence between bdelloids and prokaryotes sheds new light on the evolutionary significance of sex.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Flot, Jean-Francois -- Hespeels, Boris -- Li, Xiang -- Noel, Benjamin -- Arkhipova, Irina -- Danchin, Etienne G J -- Hejnol, Andreas -- Henrissat, Bernard -- Koszul, Romain -- Aury, Jean-Marc -- Barbe, Valerie -- Barthelemy, Roxane-Marie -- Bast, Jens -- Bazykin, Georgii A -- Chabrol, Olivier -- Couloux, Arnaud -- Da Rocha, Martine -- Da Silva, Corinne -- Gladyshev, Eugene -- Gouret, Philippe -- Hallatschek, Oskar -- Hecox-Lea, Bette -- Labadie, Karine -- Lejeune, Benjamin -- Piskurek, Oliver -- Poulain, Julie -- Rodriguez, Fernando -- Ryan, Joseph F -- Vakhrusheva, Olga A -- Wajnberg, Eric -- Wirth, Benedicte -- Yushenova, Irina -- Kellis, Manolis -- Kondrashov, Alexey S -- Mark Welch, David B -- Pontarotti, Pierre -- Weissenbach, Jean -- Wincker, Patrick -- Jaillon, Olivier -- Van Doninck, Karine -- England -- Nature. 2013 Aug 22;500(7463):453-7. doi: 10.1038/nature12326. Epub 2013 Jul 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉University of Namur, Department of Biology, URBE, Laboratory of Evolutionary Genetics and Ecology, 5000 Namur, Belgium. jean-francois.flot@ds.mpg.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23873043" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Gene Conversion/*genetics ; Gene Transfer, Horizontal/genetics ; Genome/*genetics ; Genomics ; Meiosis/genetics ; Models, Biological ; Reproduction, Asexual/*genetics ; Rotifera/*genetics ; Tetraploidy
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2014-03-29
    Description: Rapid advances in DNA synthesis techniques have made it possible to engineer viruses, biochemical pathways and assemble bacterial genomes. Here, we report the synthesis of a functional 272,871-base pair designer eukaryotic chromosome, synIII, which is based on the 316,617-base pair native Saccharomyces cerevisiae chromosome III. Changes to synIII include TAG/TAA stop-codon replacements, deletion of subtelomeric regions, introns, transfer RNAs, transposons, and silent mating loci as well as insertion of loxPsym sites to enable genome scrambling. SynIII is functional in S. cerevisiae. Scrambling of the chromosome in a heterozygous diploid reveals a large increase in a-mater derivatives resulting from loss of the MATalpha allele on synIII. The complete design and synthesis of synIII establishes S. cerevisiae as the basis for designer eukaryotic genome biology.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4033833/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4033833/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Annaluru, Narayana -- Muller, Heloise -- Mitchell, Leslie A -- Ramalingam, Sivaprakash -- Stracquadanio, Giovanni -- Richardson, Sarah M -- Dymond, Jessica S -- Kuang, Zheng -- Scheifele, Lisa Z -- Cooper, Eric M -- Cai, Yizhi -- Zeller, Karen -- Agmon, Neta -- Han, Jeffrey S -- Hadjithomas, Michalis -- Tullman, Jennifer -- Caravelli, Katrina -- Cirelli, Kimberly -- Guo, Zheyuan -- London, Viktoriya -- Yeluru, Apurva -- Murugan, Sindurathy -- Kandavelou, Karthikeyan -- Agier, Nicolas -- Fischer, Gilles -- Yang, Kun -- Martin, J Andrew -- Bilgel, Murat -- Bohutski, Pavlo -- Boulier, Kristin M -- Capaldo, Brian J -- Chang, Joy -- Charoen, Kristie -- Choi, Woo Jin -- Deng, Peter -- DiCarlo, James E -- Doong, Judy -- Dunn, Jessilyn -- Feinberg, Jason I -- Fernandez, Christopher -- Floria, Charlotte E -- Gladowski, David -- Hadidi, Pasha -- Ishizuka, Isabel -- Jabbari, Javaneh -- Lau, Calvin Y L -- Lee, Pablo A -- Li, Sean -- Lin, Denise -- Linder, Matthias E -- Ling, Jonathan -- Liu, Jaime -- Liu, Jonathan -- London, Mariya -- Ma, Henry -- Mao, Jessica -- McDade, Jessica E -- McMillan, Alexandra -- Moore, Aaron M -- Oh, Won Chan -- Ouyang, Yu -- Patel, Ruchi -- Paul, Marina -- Paulsen, Laura C -- Qiu, Judy -- Rhee, Alex -- Rubashkin, Matthew G -- Soh, Ina Y -- Sotuyo, Nathaniel E -- Srinivas, Venkatesh -- Suarez, Allison -- Wong, Andy -- Wong, Remus -- Xie, Wei Rose -- Xu, Yijie -- Yu, Allen T -- Koszul, Romain -- Bader, Joel S -- Boeke, Jef D -- Chandrasegaran, Srinivasan -- 092076/Wellcome Trust/United Kingdom -- GM077291/GM/NIGMS NIH HHS/ -- R01 GM077291/GM/NIGMS NIH HHS/ -- R01 GM090192/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2014 Apr 4;344(6179):55-8. doi: 10.1126/science.1249252. Epub 2014 Mar 27.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Environmental Health Sciences, Johns Hopkins University (JHU) School of Public Health, Baltimore, MD 21205, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24674868" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; *Chromosomes, Fungal/genetics/metabolism ; DNA, Fungal/genetics ; Genes, Fungal ; Genetic Fitness ; Genome, Fungal ; Genomic Instability ; Introns ; Molecular Sequence Data ; Mutation ; Polymerase Chain Reaction ; RNA, Fungal/genetics ; RNA, Transfer/genetics ; Saccharomyces cerevisiae/cytology/*genetics/physiology ; Sequence Analysis, DNA ; Sequence Deletion ; Synthetic Biology/*methods ; Transformation, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2014-07-19
    Description: Motivations: De novo sequencing of genomes is followed by annotation analyses aiming at identifying functional genomic features such as genes, non-coding RNAs or regulatory sequences, taking advantage of diverse datasets. These steps sometimes fail at detecting non-coding functional sequences: for example, origins of replication, centromeres and rDNA positions have proven difficult to annotate with high confidence. Here, we demonstrate an unconventional application of Chromosome Conformation Capture (3C) technique, which typically aims at deciphering the average 3D organization of genomes, by showing how functional information about the sequence can be extracted solely from the chromosome contact map. Results: Specifically, we describe a combined experimental and bioinformatic procedure that determines the genomic positions of centromeres and ribosomal DNA clusters in yeasts, including species where classical computational approaches fail. For instance, we determined the centromere positions in Naumovozyma castellii , where these coordinates could not be obtained previously. Although computed centromere positions were characterized by conserved synteny with neighboring species, no consensus sequences could be found, suggesting that centromeric binding proteins or mechanisms have significantly diverged. We also used our approach to refine centromere positions in Kuraishia capsulata and to identify rDNA positions in Debaryomyces hansenii . Our study demonstrates how 3C data can be used to complete the functional annotation of eukaryotic genomes. Availability and implementation: The source code is provided in the Supplementary Material. This includes a zipped file with the Python code and a contact matrix of Saccharomyces cerevisiae . Contact: romain.koszul@pasteur.fr Supplementary information: Supplementary data are available at Bioinformatics online
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
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  • 4
    Publication Date: 2018
    Description: 〈p〉In chromosome conformation capture experiments (Hi-C), the accuracy with which contacts are detected varies due to the uneven distribution of restriction sites along genomes. In addition, repeated sequences or homologous regions remain indistinguishable because of the ambiguities they introduce during the alignment of the sequencing reads. We addressed both limitations by designing and engineering 144 kb of a yeast chromosome with regularly spaced restriction sites (Syn-HiC design). In the Syn-HiC region, Hi-C signal-to-noise ratio is enhanced and can be used to measure the shape of an unbiased distribution of contact frequencies, allowing to propose a robust definition of a Hi-C experiment resolution. The redesigned region is also distinguishable from its native homologous counterpart in an otherwise isogenic diploid strain. As a proof of principle, we tracked homologous chromosomes during meiotic prophase in synchronized and pachytene-arrested cells and captured important features of their spatial reorganization, such as chromatin restructuration into arrays of Rec8-delimited loops, centromere declustering, individualization, and pairing. Overall, we illustrate the promises held by redesigning genomic regions to explore complex biological questions.〈/p〉
    Electronic ISSN: 1744-4292
    Topics: Biology
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  • 5
    Publication Date: 2016-04-28
    Description: Bacteria with multiple chromosomes represent up to 10% of all bacterial species. Unlike eukaryotes, these bacteria use chromosome-specific initiators for their replication. In all cases investigated, the machineries for secondary chromosome replication initiation are of plasmid origin. One of the important differences between plasmids and chromosomes is that the latter replicate during a defined period of the cell cycle, ensuring a single round of replication per cell. Vibrio cholerae carries two circular chromosomes, Chr1 and Chr2, which are replicated in a well-orchestrated manner with the cell cycle and coordinated in such a way that replication termination occurs at the same time. However, the mechanism coordinating this synchrony remains speculative. We investigated this mechanism and revealed that initiation of Chr2 replication is triggered by the replication of a 150-bp locus positioned on Chr1, called crtS . This crtS replication–mediated Chr2 replication initiation mechanism explains how the two chromosomes communicate to coordinate their replication. Our study reveals a new checkpoint control mechanism in bacteria, and highlights possible functional interactions mediated by contacts between two chromosomes, an unprecedented observation in bacteria.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 6
    Publication Date: 2016-01-09
    Description: The potential roles of the numerous repetitive elements found in the genomes of multi-cellular organisms remain speculative. Several studies have suggested a role in stabilizing specific 3D genomic contacts. To test this hypothesis, we exploited inter-chromosomal contacts frequencies obtained from Hi-C experiments and show that the folding of the human, mouse and Drosophila genomes is associated with a significant co-localization of several specific repetitive elements, notably many elements of the SINE family. These repeats tend to be the oldest ones and are enriched in transcription factor binding sites. We propose that the co-localization of these repetitive elements may explain the global conservation of genome folding observed between homologous regions of the human and mouse genome. Taken together, these results support a contribution of specific repetitive elements in maintaining and/or reshaping genome architecture over evolutionary times.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 7
    Publication Date: 2017-02-19
    Description: The biochemical activities of microbial communities, or microbiomes, are essential parts of environmental and animal ecosystems. The dynamics, balance, and effects of these communities are strongly influenced by phages present in the population. Being able to characterize bacterium-phage relationships is therefore essential to investigate these ecosystems to the full extent of their complexity. However, this task is currently limited by (i) the ability to characterize complete bacterial and viral genomes from a complex mix of species and (ii) the difficulty to assign phage sequences to their bacterial hosts. We show that both limitations can be circumvented using meta3C, an experimental and computational approach that exploits the physical contacts between DNA molecules to infer their proximity. In a single experiment, dozens of bacterial and phage genomes present in a complex mouse gut microbiota were assembled and scaffolded de novo. The phage genomes were then assigned to their putative bacterial hosts according to the physical contacts between the different DNA molecules, opening new perspectives for a comprehensive picture of the genomic structure of the gut flora. Therefore, this work holds far-reaching implications for human health studies aiming to bridge the virome to the microbiome.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 8
    Publication Date: 2008-06-01
    Print ISSN: 0092-8674
    Electronic ISSN: 1097-4172
    Topics: Biology , Medicine
    Published by Cell Press
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