scholarly journals GingerRoot: A Novel DNA Transposon Encoding Integrase-Related Transposase in Plants and Animals

2019 ◽  
Vol 11 (11) ◽  
pp. 3181-3193
Author(s):  
Stefan Cerbin ◽  
Ching Man Wai ◽  
Robert VanBuren ◽  
Ning Jiang
Keyword(s):  
Animal Species ◽  
Catalytic Domain ◽  
De Novo ◽  
Long Terminal Repeat Retrotransposons ◽  
Dna Transposon ◽  
Coral Sea ◽  
Considerable Portion ◽  
Selaginella Lepidophylla ◽  
Gypsy Retrotransposons ◽  
Eukaryotic Genomes

Abstract Transposable elements represent the largest components of many eukaryotic genomes and different genomes harbor different combinations of elements. Here, we discovered a novel DNA transposon in the genome of the clubmoss Selaginella lepidophylla. Further searching for related sequences to the conserved DDE region uncovered the presence of this superfamily of elements in fish, coral, sea anemone, and other animal species. However, this element appears restricted to Bryophytes and Lycophytes in plants. This transposon, named GingerRoot, is associated with a 6 bp (base pair) target site duplication, and 100–150 bp terminal inverted repeats. Analysis of transposase sequences identified the DDE motif, a catalytic domain, which shows similarity to the integrase of Gypsy-like long terminal repeat retrotransposons, the most abundant component in plant genomes. A total of 77 intact and several hundred truncated copies of GingerRoot elements were identified in S. lepidophylla. Like Gypsy retrotransposons, GingerRoots show a lack of insertion preference near genes, which contrasts to the compact genome size of about 100 Mb. Nevertheless, a considerable portion of GingerRoot elements was found to carry gene fragments, suggesting the capacity of duplicating gene sequences is unlikely attributed to the proximity to genes. Elements carrying gene fragments appear to be less methylated, more diverged, and more distal to genes than those without gene fragments, indicating they are preferentially retained in gene-poor regions. This study has identified a broadly dispersed, novel DNA transposon, and the first plant DNA transposon with an integrase-related transposase, suggesting the possibility of de novo formation of Gypsy-like elements in plants.

scholarly journals Benchmarking transposable element annotation methods for creation of a streamlined, comprehensive pipeline

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Shujun Ou ◽  
Weija Su ◽  
Yi Liao ◽  
Kapeel Chougule ◽  
Jireh R. A. Agda ◽  
...  
Keyword(s):  
Transposable Elements ◽  
Animal Species ◽  
Performance Metrics ◽  
De Novo ◽  
Terminal Inverted Repeat ◽  
Miniature Inverted Transposable Elements ◽  
Sensitivity Specificity ◽  
Genomic Regions ◽  
Assembly Algorithms ◽  
Eukaryotic Genomes

Abstract Background Sequencing technology and assembly algorithms have matured to the point that high-quality de novo assembly is possible for large, repetitive genomes. Current assemblies traverse transposable elements (TEs) and provide an opportunity for comprehensive annotation of TEs. Numerous methods exist for annotation of each class of TEs, but their relative performances have not been systematically compared. Moreover, a comprehensive pipeline is needed to produce a non-redundant library of TEs for species lacking this resource to generate whole-genome TE annotations. Results We benchmark existing programs based on a carefully curated library of rice TEs. We evaluate the performance of methods annotating long terminal repeat (LTR) retrotransposons, terminal inverted repeat (TIR) transposons, short TIR transposons known as miniature inverted transposable elements (MITEs), and Helitrons. Performance metrics include sensitivity, specificity, accuracy, precision, FDR, and F1. Using the most robust programs, we create a comprehensive pipeline called Extensive de-novo TE Annotator (EDTA) that produces a filtered non-redundant TE library for annotation of structurally intact and fragmented elements. EDTA also deconvolutes nested TE insertions frequently found in highly repetitive genomic regions. Using other model species with curated TE libraries (maize and Drosophila), EDTA is shown to be robust across both plant and animal species. Conclusions The benchmarking results and pipeline developed here will greatly facilitate TE annotation in eukaryotic genomes. These annotations will promote a much more in-depth understanding of the diversity and evolution of TEs at both intra- and inter-species levels. EDTA is open-source and freely available: https://github.com/oushujun/EDTA.

scholarly journals Interplay between Histone and DNA Methylation Seen through Comparative Methylomes in Rare Mendelian Disorders

2021 ◽  
Vol 22 (7) ◽  
pp. 3735
Author(s):  
Guillaume Velasco ◽  
Damien Ulveling ◽  
Sophie Rondeau ◽  
Pauline Marzin ◽  
Motoko Unoki ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Catalytic Domain ◽  
De Novo ◽  
Mutation Screening ◽  
Histone H3 ◽  
Regulatory Elements ◽  
Germline Mutations ◽  
Dna Methyltransferases ◽  
Mendelian Disorders ◽  
Epigenetic Machinery

DNA methylation (DNAme) profiling is used to establish specific biomarkers to improve the diagnosis of patients with inherited neurodevelopmental disorders and to guide mutation screening. In the specific case of mendelian disorders of the epigenetic machinery, it also provides the basis to infer mechanistic aspects with regard to DNAme determinants and interplay between histone and DNAme that apply to humans. Here, we present comparative methylomes from patients with mutations in the de novo DNA methyltransferases DNMT3A and DNMT3B, in their catalytic domain or their N-terminal parts involved in reading histone methylation, or in histone H3 lysine (K) methylases NSD1 or SETD2 (H3 K36) or KMT2D/MLL2 (H3 K4). We provide disease-specific DNAme signatures and document the distinct consequences of mutations in enzymes with very similar or intertwined functions, including at repeated sequences and imprinted loci. We found that KMT2D and SETD2 germline mutations have little impact on DNAme profiles. In contrast, the overlapping DNAme alterations downstream of NSD1 or DNMT3 mutations underlines functional links, more specifically between NSD1 and DNMT3B at heterochromatin regions or DNMT3A at regulatory elements. Together, these data indicate certain discrepancy with the mechanisms described in animal models or the existence of redundant or complementary functions unforeseen in humans.

scholarly journals Structural insights into CpG-specific DNA methylation by human DNA methyltransferase 3B

2020 ◽  
Vol 48 (7) ◽  
pp. 3949-3961 ◽  
Author(s):  
Chien-Chu Lin ◽  
Yi-Ping Chen ◽  
Wei-Zen Yang ◽  
James C K Shen ◽  
Hanna S Yuan
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferase ◽  
Cytosine Methylation ◽  
Catalytic Domain ◽  
De Novo ◽  
Water Channel ◽  
Dna Methyltransferases ◽  
Structural Basis ◽  
Cpg Sites ◽  
Methylation Patterns

Abstract DNA methyltransferases are primary enzymes for cytosine methylation at CpG sites of epigenetic gene regulation in mammals. De novo methyltransferases DNMT3A and DNMT3B create DNA methylation patterns during development, but how they differentially implement genomic DNA methylation patterns is poorly understood. Here, we report crystal structures of the catalytic domain of human DNMT3B–3L complex, noncovalently bound with and without DNA of different sequences. Human DNMT3B uses two flexible loops to enclose DNA and employs its catalytic loop to flip out the cytosine base. As opposed to DNMT3A, DNMT3B specifically recognizes DNA with CpGpG sites via residues Asn779 and Lys777 in its more stable and well-ordered target recognition domain loop to facilitate processive methylation of tandemly repeated CpG sites. We also identify a proton wire water channel for the final deprotonation step, revealing the complete working mechanism for cytosine methylation by DNMT3B and providing the structural basis for DNMT3B mutation-induced hypomethylation in immunodeficiency, centromere instability and facial anomalies syndrome.

scholarly journals Software Evaluation for de novo Detection of Transposons

2021 ◽  
Author(s):  
Matias Rodriguez ◽  
Wojciech Makałowski
Keyword(s):  
Transposable Elements ◽  
Genome Evolution ◽  
De Novo ◽  
Simulated Data ◽  
Genomic Sequences ◽  
Software Evaluation ◽  
Easy Task ◽  
Eukaryotic Genomes

AbstractTransposable elements (TEs) are major genomic components in most eukaryotic genomes and play an important role in genome evolution. However, despite their relevance the identification of TEs is not an easy task and a number of tools were developed to tackle this problem. To better understand how they perform, we tested several widely used tools for de novo TE detection and compared their performance on both simulated data and well curated genomic sequences. The results will be helpful for identifying common issues associated with TE-annotation and for evaluating how comparable are the results obtained with different tools.

scholarly journals gcaPDA: A Haplotype-resolved Diploid Assembler

2021 ◽  
Author(s):  
Xie Min ◽  
Linfeng Yang ◽  
Chenglin Jiang ◽  
Shenshen Wu ◽  
Cheng Luo ◽  
...  
Keyword(s):  
De Novo ◽  
Low Complexity ◽  
F1 Hybrid ◽  
Functional Studies ◽  
Assembly Result ◽  
Eukaryotic Genomes

Generating chromosome-scale haplotype resolved assembly is important for functional studies. However, current de novo assemblers are either haploid assemblers that discard allelic information, or diploid assemblers that can only tackle genomes of low complexity. Here, we report a diploid assembler, gcaPDA (gamete cells assisted Phased Diploid Assembler), which exploits haploid gamete cells to assist in resolving haplotypes. We generate chromosome-scale phased diploid assemblies for the highly heterozygous and repetitive genome of a maize F1 hybrid using gcaPDA and evaluate the assembly result thoroughly. With applicability of coping with complex genomes and fewer restrictions on application than other diploid assemblers, gcaPDA is likely to find broad applications in studies of eukaryotic genomes.

scholarly journals Natural Bactericidal Antibodies: Observations on the Bactericidal Mechanism of Normal Serum

1931 ◽  
Vol 31 (1) ◽  
pp. 35-55 ◽  
Author(s):  
T. J. Mackie ◽  
M. H. Finkelstein
Keyword(s):  
Analytical Study ◽  
Animal Species ◽  
De Novo ◽  
Carbonic Acid ◽  
Insoluble Fraction ◽  
Normal Serum ◽  
Natural Antibodies ◽  
Bactericidal Action ◽  
Bactericidal Antibody ◽  
High Degree

1. An analytical study has been made of the mechanism of natural bactericidal action by the serum of various animals (ox, sheep, horse, rabbit, guinea-pig, rat, man) towards certain organisms (B. typhosus, B. dysenteriae Shiga, B. proteus, V. cholerae) exhibiting the maximum reactivity to this effect.2. Serum-complement has no bactericidal action per se, and an antibodylike agent invariably acts as an intermediary agent, “sensitising” the particular organism to the action of the complement and capable of being “absorbed” by it from serum at 0° C.3. This sensitising agent is stable at 55° C. but labile at 60°–65° C. In this respect it resembles natural haemolysins and agglutinins, but contrasts with the more stable immune antibodies and the more labile natural complement-fixing antibodies (for bacterial antigens). It is resident mainly in the carbonic-acid-insoluble fraction of the serum. It is present in the serum of young animals before certain other natural antibodies have developed.4. Absorption tests demonstrate the high degree of specificity of these natural bactericidal antibodies for particular bacteria.5. A non-specific extracellular substance occurs in bacterial cultures which may neutralise or inhibit these antibodies, and interfere with their sensitising action even at 0° C.6. This substance is liberated in large amount in cultures heated at high temperatures (120° C). It can be removed by repeated washing of growths in saline solution. It may inactivate a bactericidal antibody in heated serum, though not in fresh unheated serum, and may inactivate a particular antibody in the serum of one animal species but not in another. Strains of bacteria vary in their production of this substance.7. The observations submitted in this paper, correlated with previous studies of natural antibodies by the authors and others, indicate that immune antibodies have their precursors specifically differentiated in the serum of normal animals and that, in general, immune antibodies are not substances formed de novo.

scholarly journals A chromosome-scale assembly of the sorghum genome using nanopore sequencing and optical mapping

2018 ◽  
Author(s):  
Stáphane Deschamps ◽  
Yun Zhang ◽  
Victor Llaca ◽  
Liang Ye ◽  
Gregory May ◽  
...  
Keyword(s):  
Sorghum Bicolor ◽  
De Novo ◽  
Hybrid Assembly ◽  
The Public ◽  
Sequencing Technologies ◽  
Oxford Nanopore ◽  
Long Read ◽  
Optical Maps ◽  
Eukaryotic Genomes ◽  
Direct Label

The advent of long-read sequencing technologies has greatly facilitated assemblies of large eukaryotic genomes. In this paper, Oxford Nanopore sequences generated on a MinION sequencer were combined with BioNano Genomics Direct Label and Stain (DLS) optical maps to generate a chromosome-scale de novo assembly of the repeat-rich Sorghum bicolor Tx430 genome. The final hybrid assembly consists of 29 scaffolds, encompassing in most cases entire chromosome arms. It has a scaffold N50 value of 33.28Mbps and covers >90% of Sorghum bicolor expected genome length. A sequence accuracy of 99.67% was obtained in unique regions after aligning contigs against Illumina Tx430 data. Alignments showed that 99.4% of the 34,211 public gene models are present in the assembly, including 94.2% mapping end-to-end. Comparisons of the DLS optical maps against the public Sorghum Bicolor v3.0.1 BTx623 genome assembly suggest the presence of substantial genomic rearrangements whose origin remains to be determined.

scholarly journals DeepTE: a computational method for de novo classification of transposons with convolutional neural network

2020 ◽  
Author(s):  
Haidong Yan ◽  
Aureliano Bombarely ◽  
Song Li
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
De Novo ◽  
Genomic Sequence ◽  
Computational Method ◽  
Model Species ◽  
Essential Step ◽  
Genomic Sequence Analysis ◽  
Eukaryotic Genomes

AbstractMotivationTransposable elements (TEs) classification is an essential step to decode their roles in genome evolution. With a large number of genomes from non-model species becoming available, accurate and efficient TE classification has emerged as a new challenge in genomic sequence analysis.ResultsWe developed a novel tool, DeepTE, which classifies unknown TEs using convolutional neural networks. DeepTE transferred sequences into input vectors based on k-mer counts. A tree structured classification process was used where eight models were trained to classify TEs into super families and orders. DeepTE also detected domains inside TEs to correct false classification. An additional model was trained to distinguish between non-TEs and TEs in plants. Given unclassified TEs of different species, DeepTE can classify TEs into seven orders, which include 15, 24, and 16 super families in plants, metazoans, and fungi, respectively. In several benchmarking tests, DeepTE outperformed other existing tools for TE classification. In conclusion, DeepTE successfully leverages convolutional neural network for TE classification, and can be used to precisely identify and annotate TEs in newly sequenced eukaryotic genomes.AvailabilityDeepTE is accessible at https://github.com/LiLabAtVT/[email protected]

scholarly journals Disentangling sRNA-Seq data to study RNA communication between species

2019 ◽  
Author(s):  
JR Bermúdez-Barrientos ◽  
O Ramírez-Sánchez ◽  
FWN Chow ◽  
AH Buck ◽  
C Abreu-Goodger
Keyword(s):  
Small Rnas ◽  
Animal Species ◽  
De Novo ◽  
Extracellular Vesicle ◽  
Host Cells ◽  
Symbiotic System ◽  
Defense Strategies ◽  
Bioinformatic Tools ◽  
Genomic Regions ◽  
Diverse Plant

ABSTRACTMany organisms exchange small RNAs during their interactions, and these RNAs can target or bolster defense strategies in host-pathogen systems. Current sRNA-Seq technology can determine the small RNAs present in any symbiotic system, but there are very few bioinformatic tools available to interpret the results. We show that one of the biggest challenges comes from sequences that map equally well to the genomes of both interacting organisms. This arises due to the small size of the sRNA compared to large genomes, and because many of the produced sRNAs come from genomic regions that encode highly conserved miRNAs, rRNAs or tRNAs. Here we present strategies to disentangle sRNA-Seq data from samples of communicating organisms, developed using diverse plant and animal species that are known to exchange RNA with their parasites. We show that sequence assembly, both de novo and genome-guided, can be used for sRNA-Seq data, greatly reducing the ambiguity of mapping reads. Even confidently mapped sequences can be misleading, so we further demonstrate the use of differential expression strategies to determine the true parasitic sRNAs within host cells. Finally, we validate our methods on new experiments designed to probe the nature of the extracellular vesicle sRNAs from the parasitic nematode H. bakeri that get into mouse epithelial cells.

scholarly journals Analysis of genomic DNA methylation and gene transcription modulation induced by DNMT3A deficiency in HEK293 cells

2020 ◽  
Author(s):  
Mengxiao Zhang ◽  
Jiaxian Wang ◽  
Qiuxiang Tian ◽  
Lei Feng ◽  
Hui Yang ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Cell Growth ◽  
Transcriptional Repression ◽  
Catalytic Domain ◽  
De Novo ◽  
Epigenetic Modification ◽  
Cell Metabolism ◽  
Dna Methyltransferases ◽  
Hek293 Cells ◽  
Signal Pathways

AbstractDNA methylation is an important epigenetic modification associated with transcriptional repression, and plays key roles in normal cell growth as well as oncogenesis. Among the three main DNA methyltransferases (DNMT1, DNMT3A, and DNMT3B), DNMT3A mediates de novo DNA methylation with partial functional redundancy with DNMT3B. However, the general effects of DNMT3A and its downstream gene regulation profile are yet to be unveiled. In the present study, we used CRISPR/Cas9 technology to successfully create DNMT3A deficient human embryonic kidney cell line HEK293, with frameshift mutations in its catalytic domain. Our results showed that the cell growth slowed down in DNMT3A knockout cells. UPLC-MS analysis of DNMT3A deficient cells showed that the genome-level DNA methylation was reduced by 21.5% and led to an impairment of cell proliferation as well as a blockage of MAPK and PI3K-Akt pathways. Whole genome RNA-seq revealed that DNMT3A knockout up-regulated expression of genes and pathways related to cell metabolism but down-regulated those involved in ribosome function, which explained the inhibition of cell growth and related signal pathways. Further, bisulfite DNA treatment showed that DNMT3A ablation reduced the methylation level of DNMT3B gene as well, indicating the higher DNMT3B activity and thereby explaining those down-regulated profiles of genes.

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