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Jamie McCann, Tae-Soo Jang, Jiri Macas, Gerald M Schneeweiss, Nicholas J Matzke, Petr Novák, Tod F Stuessy, José L Villaseñor, Hanna Weiss-Schneeweiss
Allopolyploidy has played an important role in the evolution of the flowering plants. Genome mergers are often accompanied by significant and rapid alterations of genome size and structure via chromosomal rearrangements and altered dynamics of tandem and dispersed repetitive DNA families. Recent developments in sequencing technologies and bioinformatic methods allow for a comprehensive investigation of the repetitive component of plant genomes. Interpretation of evolutionary dynamics following allopolyploidization requires both the knowledge of parentage and the age of origin of an allopolyploid...
March 19, 2018: Systematic Biology
Andrew C Peifer, Patrick H Maxwell
Retrotransposons are abundant mobile DNA elements in eukaryotic genomes that are more active with age in diverse species. Details of the regulation and consequences of retrotransposon activity during aging remain to be determined. Ty1 retromobility in Saccharomyces cerevisiae is more frequent in mother cells compared to daughter cells, and we found that Ty1 was more mobile in nonquiescent compared to quiescent subpopulations of stationary phase cells. This retromobility asymmetry was absent in mutant strains lacking BRP1 that have reduced expression of the essential Pma1p plasma membrane proton pump, lacking the mRNA decay gene LSM1 , and in cells exposed to a high concentration of calcium...
March 21, 2018: Aging
Nikolaos P Daskalakis, Allison C Provost, Richard G Hunter, Guia Guffanti
Posttraumatic stress disorder (PTSD) is a pathologic response to trauma that impacts ∼8% of the population and is highly comorbid with other disorders, such as traumatic brain injury. PTSD affects multiple biological systems throughout the body, including the hypothalamic-pituitary-adrenal axis, cortical function, and the immune system, and while the study of the biological underpinnings of PTSD and related disorders are numerous, the roles of noncoding RNAs (ncRNAs) are just emerging. Moreover, deep sequencing has revealed that ncRNAs represent most of the transcribed mammalian genome...
January 31, 2018: Biological Psychiatry
Andrew A Bartlett, Richard G Hunter
The brain is responsible for both recognition and adaptation to stressful stimuli. Many molecular mechanisms have been implicated in this response including those governing neuronal plasticity, neurogenesis and, changes gene expression. Far less is known regarding effects of stress on the deep genome. In the hippocampus, stress appears to regulate expression of non-coding elements of the genome as well as the chromatin permissive for their transcription. Specifically, hippocampal retrotransposon (RT) elements are regulated by acute stress via the accumulation of the repressive H3K9me3 mark at RT loci...
March 15, 2018: Frontiers in Neuroendocrinology
Kyuha Choi, Xiaohui Zhao, Andrew J Tock, Christophe Lambing, Charles J Underwood, Thomas J Hardcastle, Heïdi Serra, Juhyun Kim, Hyun Seob Cho, Jaeil Kim, Piotr A Ziolkowski, Nataliya E Yelina, Ildoo Hwang, Robert A Martienssen, Ian R Henderson
Meiotic recombination initiates from DNA double-strand breaks (DSBs) generated by SPO11 topoisomerase-like complexes. Meiotic DSB frequency varies extensively along eukaryotic chromosomes, with hotspots controlled by chromatin and DNA sequence. To map meiotic DSBs throughout a plant genome, we purified and sequenced Arabidopsis thaliana SPO11-1-oligonucleotides. SPO11-1-oligos are elevated in gene promoters, terminators, and introns, which is driven by AT-sequence richness that excludes nucleosomes and allows SPO11-1 access...
March 12, 2018: Genome Research
Jyoti Roy, Bibekanand Mallick
Remarkable attempts have been exercised in recent years using high-throughput technologies to identify and decipher the functions of piRNAs in various abnormalities like cancer. However, piRNAs in the oncogenesis of neuroblastoma (NB) has not been reported yet even after their illustrated roles in neurological processes. Therefore, we investigated the piRNA transcriptome in IMR-32 and SH-SY-5Y NB cell lines by employing high-throughput next-generation sequencing after confirming the expression of three associated PIWILs both at mRNAs and protein level by qRT-PCR and immunofluroscence respectively...
March 8, 2018: Genes, Chromosomes & Cancer
Savrina Manhas, Lina Ma, Vivien Measday
Nuclear pore complexes (NPCs) orchestrate cargo between the cytoplasm and nucleus and regulate chromatin organization. NPC proteins, or nucleoporins (Nups), are required for human immunodeficiency virus type 1 (HIV-1) gene expression and genomic integration of viral DNA. We utilize the Ty1 retrotransposon of Saccharomyces cerevisiae (S. cerevisiae) to study retroviral integration because retrotransposons are the progenitors of retroviruses and have conserved integrase (IN) enzymes. Ty1-IN targets Ty1 elements into the genome upstream of RNA polymerase (Pol) III transcribed genes such as transfer RNA (tRNA) genes...
March 5, 2018: Nucleic Acids Research
Viktor Tokan, Janka Puterova, Matej Lexa, Eduard Kejnovsky
BACKGROUND: Many studies have shown that guanine-rich DNA sequences form quadruplex structures (G4) in vitro but there is scarce evidence of guanine quadruplexes in vivo. The majority of potential quadruplex-forming sequences (PQS) are located in transposable elements (TEs), especially close to promoters within long terminal repeats of plant LTR retrotransposons. RESULTS: In order to test the potential effect of G4s on retrotransposon expression, we cloned the long terminal repeats of selected maize LTR retrotransposons upstream of the lacZ reporter gene and measured its transcription and translation in yeast...
March 6, 2018: BMC Genomics
Ying Jin, Molly Hammell
Transposable elements (TE) are mobile genetic elements that can readily change their genomic position. When not properly silenced, TEs can contribute a substantial portion to the cell's transcriptome, but are typically ignored in most RNA-seq data analyses. One reason for leaving TE-derived reads out of RNA-seq analyses is the complexities involved in properly aligning short sequencing reads to these highly repetitive regions. Here we describe a method for including TE-derived reads in RNA-seq differential expression analysis using an open source software package called TEtranscripts...
2018: Methods in Molecular Biology
Vikas Yadav, Sheng Sun, R Blake Billmyre, Bhagya C Thimmappa, Terrance Shea, Robert Lintner, Guus Bakkeren, Christina A Cuomo, Joseph Heitman, Kaustuv Sanyal
The centromere DNA locus on a eukaryotic chromosome facilitates faithful chromosome segregation. Despite performing such a conserved function, centromere DNA sequence as well as the organization of sequence elements is rapidly evolving in all forms of eukaryotes. The driving force that facilitates centromere evolution remains an enigma. Here, we studied the evolution of centromeres in closely related species in the fungal phylum of Basidiomycota. Using ChIP-seq analysis of conserved inner kinetochore proteins, we identified centromeres in three closely related Cryptococcus species: two of which are RNAi-proficient, while the other lost functional RNAi...
March 5, 2018: Proceedings of the National Academy of Sciences of the United States of America
Peter A Larson, John B Moldovan, Naveen Jasti, Jeffrey M Kidd, Christine R Beck, John V Moran
Human Long interspersed element-1 (L1) retrotransposons contain an internal RNA polymerase II promoter within their 5' untranslated region (UTR) and encode two proteins, (ORF1p and ORF2p) required for their mobilization (i.e., retrotransposition). The evolutionary success of L1 relies on the continuous retrotransposition of full-length L1 mRNAs. Previous studies identified functional splice donor (SD), splice acceptor (SA), and polyadenylation sequences in L1 mRNA and provided evidence that a small number of spliced L1 mRNAs retrotransposed in the human genome...
March 5, 2018: PLoS Biology
Moein Farshchian, Maryam M Matin, Olivier Armant, Dirk Geerts, Mahtab Dastpak, Saeideh Nakhaei-Rad, Massoumeh Tajeran, Amir Jebelli, Mina Shahriyari, Monireh Bahrami, Ali Fallah, Vesal Yaghoobi, Mahdi Mirahmadi, Mohammad Reza Abbaszadegan, Ahmad Reza Bahrami
The self-renewal capacity of germline derived stem cells (GSCs) makes them an ideal source for research and use in clinics. Despite the presence of active gene network similarities between embryonic stem cells (ESCs) and GSCs, there are unanswered questions regarding the roles of evolutionary conserved genes in GSCs. To determine the reprogramming potential of germ cell- specific genes, we designed a polycistronic gene cassette expressing Stella, Oct4 and Nanos2 in a lentiviral-based vector. Deep transcriptome analysis showed the activation of a set of pluripotency and germ-cell-specific markers and the downregulation of innate immune system...
March 1, 2018: Cytokine
Ulrike Böhme, Thomas D Otto, James Cotton, Sascha Steinbiss, Mandy Sanders, Samuel O Oyola, Antoine Nicot, Sylvain Gandon, Kailash P Patra, Colin Herd, Ellen Bushell, Katarzyna K Modrzynska, Oliver Billker, Joseph M Vinetz, Ana Rivero, Chris I Newbold, Matthew Berriman
Avian malaria parasites are prevalent around the world, and infect a wide diversity of bird species. Here we report the sequencing and analysis of high quality draft genome sequences for two avian malaria species, Plasmodium relictum and Plasmodium gallinaceum We identify 50 genes that are specific to avian malaria, located in an otherwise conserved core of the genome that shares gene synteny with all other sequenced malaria genomes. Phylogenetic analysis suggests that the avian malaria species form an outgroup to the mammalian Plasmodium species and using amino acid divergence between species, we estimate the avian and mammalian-infective lineages diverged in the order of 10 million years ago...
March 2, 2018: Genome Research
Renata de Castro Nunes, Simon Orozco-Arias, Dominique Crouzillat, Lukas A Mueller, Suzy R Strickler, Patrick Descombes, Coralie Fournier, Deborah Moine, Alexandre de Kochko, Priscila M Yuyama, André L L Vanzela, Romain Guyot
Centromeric regions of plants are generally composed of large array of satellites from a specific lineage of Gypsy LTR-retrotransposons, called Centromeric Retrotransposons. Repeated sequences interact with a specific H3 histone, playing a crucial function on kinetochore formation. To study the structure and composition of centromeric regions in the genus Coffea , we annotated and classified Centromeric Retrotransposons sequences from the allotetraploid C. arabica genome and its two diploid ancestors: Coffea canephora and C...
2018: Frontiers in Plant Science
Ling Wei, Li Xie, Xingwu Wang, Hongxin Ma, Liyan Lv, Lisheng Liu, Xianrang Song
Genotype-directed targeted therapy has become one of the standard treatment options for non-small cell lung cancer (NSCLC). There have been numerous limitations associated with mutation analysis of tissue samples. Consequently, mutational profile analysis of circulating cell-free DNA (cfDNA) by highly sensitive droplet digital PCR (ddPCR) assay has been developed. Possibly due to differences in cfDNA concentrations, previous studies have shown numerous discrepancies in mutation detection consistency between tissue and cfDNA...
March 1, 2018: Laboratory Investigation; a Journal of Technical Methods and Pathology
Francisco Macías, Raquel Afonso-Lehmann, Manuel C López, Inmaculada Gómez, M Carmen Thomas
Introduction: An important portion of the Trypanosoma cruzi genome is composed of mobile genetic elements, which are interspersed with genes on all chromosomes. The L1Tc non-LTR retrotransposon and its truncated version NARTc are the most highly represented and best studied of these elements. L1Tc is actively transcribed in all three forms of the Trypanosoma parasite and encodes the proteins that enable it to autonomously mobilize. This mini review discusses the enzymatic properties of L1Tc that enable its mobilization and possibly the mobilization of other non-autonomous retrotransposons in Trypanosoma...
February 2018: Current Genomics
Andrea Coluccio, Gabriela Ecco, Julien Duc, Sandra Offner, Priscilla Turelli, Didier Trono
BACKGROUND: The KZFP/KAP1 (KRAB zinc finger proteins/KRAB-associated protein 1) system plays a central role in repressing transposable elements (TEs) and maintaining parent-of-origin DNA methylation at imprinting control regions (ICRs) during the wave of genome-wide reprogramming that precedes implantation. In naïve murine embryonic stem cells (mESCs), the genome is maintained highly hypomethylated by a combination of TET-mediated active demethylation and lack of de novo methylation, yet KAP1 is tethered by sequence-specific KZFPs to ICRs and TEs where it recruits histone and DNA methyltransferases to impose heterochromatin formation and DNA methylation...
February 26, 2018: Epigenetics & Chromatin
Rahul Pisupati, Daniela Vergara, Nolan C Kane
BACKGROUND: The repetitive content of the genome, once considered to be "junk DNA", is in fact an essential component of genomic architecture and evolution. In this study, we used the genomes of three varieties of Cannabis sativa, three varieties of Humulus lupulus and one genotype of Morus notabilis to explore their repetitive content using a graph-based clustering method, designed to explore and compare repeat content in genomes that have not been fully assembled. RESULTS: The repetitive content in the C...
February 21, 2018: BMC Genomics
Sandra L Martin
The mechanisms by which a retrotransposon called LINE-1 duplicates itself and spreads through the human genome are becoming clearer.
February 21, 2018: ELife
Hainan Zhao, Wenli Zhang, Lifen Chen, Lei Wang, Alexandre P Marand, Yufeng Wu, Jiming Jiang
Genomic regions free of nucleosomes are hypersensitive to DNase I digestion. These genomic regions are known as DNase I hypersensitive sites (DHSs) and frequently contain cis-regulatory DNA elements. We developed high-resolution genome-wide DHS maps in maize using a modified DNase-seq technique. Maize DHSs exhibit depletion of nucleosomes and low levels of DNA methylation, and are enriched with conserved non-coding sequences (CNSs). We developed a protoplast-based transient transformation assay to validate the potential enhancer and/or promoter functions associated with DHSs...
February 20, 2018: Plant Physiology
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