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Reuben M Buckley, R Daniel Kortschak, David L Adelson
The forces driving the accumulation and removal of non-coding DNA and ultimately the evolution of genome size in complex organisms are intimately linked to genome structure and organisation. Our analysis provides a novel method for capturing the regional variation of lineage-specific DNA gain and loss events in their respective genomic contexts. To further understand this connection we used comparative genomics to identify genome-wide individual DNA gain and loss events in the human and mouse genomes. Focusing on the distribution of DNA gains and losses, relationships to important structural features and potential impact on biological processes, we found that in autosomes, DNA gains and losses both followed separate lineage-specific accumulation patterns...
April 20, 2018: PLoS Computational Biology
Clóvis C Motta-Neto, André Marques, Gideão W W F Costa, Marcelo B Cioffi, Luiz A C Bertollo, Rodrigo X Soares, Kátia C Scortecci, Roberto F Artoni, Wagner F Molina
Representatives of the order Labriformes show karyotypes of extreme conservatism together with others with high chromosomal diversification. However, the cytological characterization of epigenetic modifications remains unknown for the majority of the species. In the family Labridae, the most abundant fishes on tropical reefs, the genomes of the genus Bodianus Bloch, 1790 have been characterized by the occurrence of a peculiar chromosomal region, here denominated BOD. This region is exceptionally decondensed, heterochromatic, argentophilic, GC-neutral and, in contrast to classical secondary constrictions, shows no signals of hybridization with 18S rDNA probes...
2018: Comparative Cytogenetics
Eliza F de M B do Nascimento, Bruna V Dos Santos, Lara O C Marques, Patricia M Guimarães, Ana C M Brasileiro, Soraya C M Leal-Bertioli, David J Bertioli, Ana C G Araujo
Peanut, Arachis hypogaea (Linnaeus, 1753) is an allotetraploid cultivated plant with two subgenomes derived from the hybridization between two diploid wild species, A. duranensis (Krapovickas & W. C. Gregory, 1994) and A. ipaensis (Krapovickas & W. C. Gregory, 1994), followed by spontaneous chromosomal duplication. To understand genome changes following polyploidy, the chromosomes of A. hypogaea , IpaDur1, an induced allotetraploid ( A. ipaensis × A. duranensis )4x and the diploid progenitor species were cytogenetically compared...
2018: Comparative Cytogenetics
Michael J Metzger, Ashley N Paynter, Mark E Siddall, Stephen P Goff
The LTR retrotransposon Steamer is a selfish endogenous element in the soft-shell clam genome that was first detected because of its dramatic amplification in bivalve transmissible neoplasia afflicting the species. We amplified and sequenced related retrotransposons from the genomic DNA of many other bivalve species, finding evidence of horizontal transfer of retrotransposons from the genome of one species to another. First, the phylogenetic tree of the Steamer -like elements from 19 bivalve species is markedly discordant with host phylogeny, suggesting frequent cross-species transfer throughout bivalve evolution...
April 18, 2018: Proceedings of the National Academy of Sciences of the United States of America
Soleimani Gezeljeh Ali, Reza Darvishzadeh, Asa Ebrahimi, Mohammad Reza Bihamta
Sunflower is an important source of edible oil. Drought is known as an important factor limiting the growth and productivity of field crops in most parts of the world. Agricultural biotechnology mainly aims at developing crops with higher tolerance to the challenging environmental conditions, such as drought. This study examined a number of morphological characters, along with relative water content (RWC) in 100 inbred sunflower lines. A 10 × 10 simple lattice design with two replications was employed to measure the mentioned parameters under natural and water-limited states during two successive years...
March 2018: Journal of Genetics
Federica Rota, Anastasia Conti, Laura Campo, Chiara Favero, Laura Cantone, Valeria Motta, Elisa Polledri, Rosa Mercadante, Giorgio Dieci, Valentina Bollati, Silvia Fustinoni
Benzene, a known human carcinogen, and methyl tert -butyl ether (MTBE), not classifiable as to its carcinogenicity, are fuel-related pollutants. This study investigated the effect of these chemicals on epigenetic and transcriptional alterations in DNA repetitive elements. In 89 petrol station workers and 90 non-occupationally exposed subjects the transcriptional activity of retrotransposons (LINE-1, Alu), the methylation on repeated-element DNA, and of H3K9 histone, were investigated in peripheral blood lymphocytes...
April 12, 2018: International Journal of Environmental Research and Public Health
Stephanie N Schauer, Patricia E Carreira, Ruchi Shukla, Daniel J Gerhardt, Patricia Gerdes, Francisco J Sanchez-Luque, Paola Nicoli, Michaela Kindlova, Serena Ghisletti, Alexandre Dos Santos, Delphine Rapoud, Didier Samuel, Jamila Faivre, Adam D Ewing, Sandra R Richardson, Geoffrey J Faulkner
The retrotransposon Long Interspersed Element 1 (LINE-1 or L1) is a continuing source of germline and somatic mutagenesis in mammals. Deregulated L1 activity is a hallmark of cancer, and L1 mutagenesis has been described in numerous human malignancies. We previously employed retrotransposon capture sequencing (RC-seq) to analyze hepatocellular carcinoma (HCC) samples from patients infected with hepatitis B or hepatitis C virus and identified L1 variants responsible for activating oncogenic pathways. Here, we have applied RC-seq and whole-genome sequencing (WGS) to an Abcb4 (Mdr2) -/- mouse model of hepatic carcinogenesis and demonstrated for the first time that L1 mobilization occurs in murine tumors...
April 11, 2018: Genome Research
Valeriya Gaysinskaya, Brendan F Miller, Chiara De Luca, Godfried W van der Heijden, Kasper D Hansen, Alex Bortvin
BACKGROUND: Meiosis is a specialized germ cell cycle that generates haploid gametes. In the initial stage of meiosis, meiotic prophase I (MPI), homologous chromosomes pair and recombine. Extensive changes in chromatin in MPI raise an important question concerning the contribution of epigenetic mechanisms such as DNA methylation to meiosis. Interestingly, previous studies concluded that in male mice, genome-wide DNA methylation patters are set in place prior to meiosis and remain constant subsequently...
April 4, 2018: Epigenetics & Chromatin
Daniela Barbieri, Emilie Elvira-Matelot, Yanis Pelinski, Laetitia Genève, Bérengère de Laval, Gayathri Yogarajah, Christian Pecquet, Stefan N Constantinescu, Françoise Porteu
Maintenance of genomic integrity is crucial for the preservation of hematopoietic stem cell (HSC) potential. Retrotransposons, spreading in the genome through an RNA intermediate, have been associated with loss of self-renewal, aging, and DNA damage. However, their role in HSCs has not been addressed. Here, we show that mouse HSCs express various retroelements (REs), including long interspersed element-1 (L1) recent family members that further increase upon irradiation. Using mice expressing an engineered human L1 retrotransposition reporter cassette and reverse transcription inhibitors, we demonstrate that L1 retransposition occurs in vivo and is involved in irradiation-induced persistent γH2AX foci and HSC loss of function...
April 3, 2018: Journal of Experimental Medicine
Akash Sookdeo, Crystal M Hepp, Stéphane Boissinot
Background: LINE-1 (L1) is the dominant autonomously replicating non-LTR retrotransposon in mammals. Although our knowledge of L1 evolution across the tree of life has considerably improved in recent years, what we know of L1 evolution in mammals is biased and comes mostly from studies in primates (mostly human) and rodents (mostly mouse). It is unclear if patterns of evolution that are shared between those two groups apply to other mammalian orders. Here we performed a detailed study on the evolution of L1 in perissodactyls by making use of the complete genome of the domestic horse and of the white rhinoceros...
2018: Mobile DNA
Natália Lourenço de Freitas, Ahmed Basheer Hamid Al-Rikabi, Luiz Antonio Carlos Bertollo, Tariq Ezaz, Cassia Fernanda Yano, Ezequiel Aguiar de Oliveira, Terumi Hatanaka, Marcelo de Bello Cioffi
Background: Species with 'young' or nascent sex chromosomes provide unique opportunities to understand early evolutionary mechanisms (e.g. accumulation of repetitive sequences, cessation of recombination and gene loss) that drive the evolution of sex chromosomes. Among vertebrates, fishes exhibit highly diverse and a wide spectrum of sex-determining mechanisms and sex chromosomes, ranging from cryptic to highly differentiated ones, as well as, from simple to multiple sex chromosome systems...
April 2018: Current Genomics
Gernot G Presting
The centromeric DNA of most multicellular eukaryotes consists of tandem repeats (TR) that bind centromere-specific proteins and act as a substrate for the efficient repair of frequent double-stranded DNA breaks. Some retrotransposons target active centromeres during integration with such specificity that they can be used to deduce current and historic centromere positions. The roles of transposons in centromere function remain incompletely understood but appear to include maintaining centromere size and increasing the repeat content of neocentromeres that lack TR...
March 26, 2018: Current Opinion in Genetics & Development
M Nabuan Naufer, Anthony V Furano, Mark C Williams
Long interspersed nuclear element 1 (LINE-1 or L1) is the dominant retrotransposon in mammalian genomes. L1 encodes two proteins ORF1p and ORF2p that are required for retrotransposition. ORF2p functions as the replicase. ORF1p is a coiled coil-mediated trimeric, high affinity RNA binding protein that packages its full- length coding transcript into an ORF2p-containing ribonucleoprotein (RNP) complex, the retrotransposition intermediate. ORF1p also is a nucleic acid chaperone that presumably facilitates the proposed nucleic acid remodeling steps involved in retrotransposition...
March 26, 2018: Seminars in Cell & Developmental Biology
Marcelo Perez-Pepe, Ana J Fernández-Alvarez, Graciela Lidia Boccaccio
The dynamic formation of stress granules (SGs), processing bodies (PBs), and related RNA organelles regulates diverse cellular processes, including the coordination of functionally connected messengers, the translational regulation at the synapse, and the control of viruses and retrotransposons. Recent studies have shown that pyruvate kinase and other enzymes localize in SGs and PBs, where they become protected from stress insults. These observations may have implications on enzyme regulation and metabolic control exerted by RNA-based organelles...
March 29, 2018: Biochemistry
Frédéric G Brunet, Benjamin Audit, Guénola Drillon, Françoise Argoul, Jean-Nicolas Volff, Alain Arneodo
Nucleosome-depleted regions around which nucleosomes order following the "statistical" positioning scenario were recently shown to be encoded in the DNA sequence in human. This intrinsic nucleosomal ordering strongly correlates with oscillations in the local GC content as well as with the interspecies and intraspecies mutation profiles, revealing the existence of both positive and negative selection. In this letter, we show that these predicted nucleosome inhibitory energy barriers (NIEBs) with compacted neighboring nucleosomes are indeed ubiquitous to all vertebrates tested...
March 23, 2018: Biophysical Journal
Maria Kordyukova, Ivan Olovnikov, Alla Kalmykova
The ends of linear eukaryotic chromosomes, telomeres, are elongated by reverse transcriptase activity provided by the enzyme telomerase, or by specialized telomeric retrotransposons. Telomerase and telomeric retrotransposons represent unique examples of structurally different, but evolutionary and functionally related machineries that generate essential chromosome structures, namely telomeres. In fact, the telomere is an example of the taming of retroelements for the maintenance of essential genome function...
March 20, 2018: Current Opinion in Genetics & Development
Elissa D Pastuzyn, Cameron E Day, Rachel B Kearns, Madeleine Kyrke-Smith, Andrew V Taibi, John McCormick, Nathan Yoder, David M Belnap, Simon Erlendsson, Dustin R Morado, John A G Briggs, Cédric Feschotte, Jason D Shepherd
No abstract text is available yet for this article.
March 22, 2018: Cell
Tracy A Bedrosian, Carolina Quayle, Nicole Novaresi, Fred H Gage
The brain is a genomic mosaic owing to somatic mutations that arise throughout development. Mobile genetic elements, including retrotransposons, are one source of somatic mosaicism in the brain. Retrotransposition may represent a form of plasticity in response to experience. Here, we use droplet digital polymerase chain reaction to show that natural variations in maternal care mediate the mobilization of long interspersed nuclear element-1 (LINE-1 or L1) retrotransposons in the hippocampus of the mouse brain...
March 23, 2018: Science
Elena Khazina, Oliver Weichenrieder
LINE-1 (L1) is an autonomous retrotransposon, which acted throughout mammalian evolution and keeps contributing to human genotypic diversity, genetic disease and cancer. L1 encodes two essential proteins: L1ORF1p, a unique RNA-binding protein, and L1ORF2p, an endonuclease and reverse transcriptase. L1ORF1p contains an essential, but rapidly evolving N-terminal portion, homo-trimerizes via a coiled coil and packages L1RNA into large assemblies. Here, we determined crystal structures of the entire coiled coil domain of human L1ORF1p...
March 22, 2018: ELife
Dustin C Hancks
Chromothripsis is a mutational event driven by tens to hundreds of double-stranded DNA breaks which occur in a single event between a limited number of chromosomes. Following chromosomal shattering, DNA fragments are stitched together in a seemingly random manner resulting in complex genomic rearrangements including sequence shuffling, deletions, and inversions of varying size. This genomic catastrophe has been observed in cancer genomes and the genomes of patients harboring developmental and congenital defects...
2018: Methods in Molecular Biology
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