scholarly journals MPE-seq, a new method for the genome-wide analysis of chromatin structure

2015 ◽  
Vol 112 (27) ◽  
pp. E3457-E3465 ◽  
Author(s):  
Haruhiko Ishii ◽  
James T. Kadonaga ◽  
Bing Ren
Keyword(s):  
Dna Sequences ◽  
Chromatin Structure ◽  
Nuclear Dna ◽  
Massively Parallel Sequencing ◽  
Nucleosome Occupancy ◽  
Regulation Of Gene Expression ◽  
Micrococcal Nuclease ◽  
Genome Wide Analysis ◽  
Genome Wide ◽  
Sequence Bias

The analysis of chromatin structure is essential for the understanding of transcriptional regulation in eukaryotes. Here we describe methidiumpropyl-EDTA sequencing (MPE-seq), a method for the genome-wide characterization of chromatin that involves the digestion of nuclei withMPE-Fe(II) followed by massively parallel sequencing. Like micrococcal nuclease (MNase), MPE-Fe(II) preferentially cleaves the linker DNA between nucleosomes. However, there are differences in the cleavage of nuclear chromatin by MPE-Fe(II) relative to MNase. Most notably, immediately upstream of the transcription start site of active promoters, we frequently observed nucleosome-sized (141–190 bp) and subnucleosome-sized (such as 101–140 bp) peaks of digested chromatin fragments with MPE-seq but not with MNase-seq. These peaks also correlate with the presence of core histones and could thus be due, at least in part, to noncanonical chromatin structures such as labile nucleosome-like particles that have been observed in other contexts. The subnucleosome-sized MPE-seq peaks exhibit a particularly distinct association with active promoters. In addition, unlike MNase, MPE-Fe(II) cleaves nuclear DNA with little sequence bias. In this regard, we found that DNA sequences at RNA splice sites are hypersensitive to digestion by MNase but not by MPE-Fe(II). This phenomenon may have affected the analysis of nucleosome occupancy over exons. These findings collectively indicate that MPE-seq provides a unique and straightforward means for the genome-wide analysis of chromatin structure with minimal DNA sequence bias. In particular, the combined use of MPE-seq and MNase-seq enables the identification of noncanonical chromatin structures that are likely to be important for the regulation of gene expression.

scholarly journals Chromatin is an ancient innovation conserved between Archaea and Eukarya

eLife ◽  
2012 ◽  
Vol 1 ◽  
Author(s):  
Ron Ammar ◽  
Dax Torti ◽  
Kyle Tsui ◽  
Marinella Gebbia ◽  
Tanja Durbic ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chromatin Structure ◽  
Nucleosome Occupancy ◽  
Regulation Of Gene Expression ◽  
Haloferax Volcanii ◽  
Dna Compaction ◽  
Genome Wide ◽  
Eukaryotic Chromatin ◽  
Transcriptional Start Sites

The eukaryotic nucleosome is the fundamental unit of chromatin, comprising a protein octamer that wraps ∼147 bp of DNA and has essential roles in DNA compaction, replication and gene expression. Nucleosomes and chromatin have historically been considered to be unique to eukaryotes, yet studies of select archaea have identified homologs of histone proteins that assemble into tetrameric nucleosomes. Here we report the first archaeal genome-wide nucleosome occupancy map, as observed in the halophile Haloferax volcanii. Nucleosome occupancy was compared with gene expression by compiling a comprehensive transcriptome of Hfx. volcanii. We found that archaeal transcripts possess hallmarks of eukaryotic chromatin structure: nucleosome-depleted regions at transcriptional start sites and conserved −1 and +1 promoter nucleosomes. Our observations demonstrate that histones and chromatin architecture evolved before the divergence of Archaea and Eukarya, suggesting that the fundamental role of chromatin in the regulation of gene expression is ancient.

scholarly journals Analysis of DNA attached to the chromosome scaffold.

1982 ◽  
Vol 93 (2) ◽  
pp. 278-284 ◽  
Author(s):  
M T Kuo
Keyword(s):  
Dna Sequences ◽  
Southern Blotting ◽  
Nuclear Dna ◽  
Micrococcal Nuclease ◽  
Nonhistone Protein ◽  
Sequence Class ◽  
Restriction Endonuclease Ecori ◽  
Cold Spring ◽  
Endonuclease Ecori ◽  
Chromosome Scaffold

Two different methods have been described to investigate whether any specific DNA sequences are intimately associated with the metaphase chromosome scaffold. The chromosome scaffold, prepared by dehistonization of chromosomes with 2 M NaCl, is a nonhistone protein complex to which many looped DNA molecules are attached (Laemmli et al., 1977, Cold Spring Harbor Symp. Quant. Biol. 42:351--360). Chromosome scaffold DNA was prepared from dehistonized chicken MSB chromosomes by restriction endonuclease EcoRI digestion followed by removal of the looped DNA by sucrose gradient sedimentation. Alternatively, the scaffold DNA was prepared from micrococcal nuclease-digested intact chromosomes using sucrose gradients containing 2M NaCl. Solution hybridization of the radioactively labeled scaffold DNA with a large excess of total nuclear DNA revealed that, in either case, the scaffold DNA is not a unique sequence class of genomic DNA. Southern-blotting hybridization also showed that the scaffold DNA prepared from EcoRI-digested dehistonized chromosomes was not enriched (or depleted) in the ovalbumin gene sequences. The possibility of a dynamic interaction of protein and DNA in the chromosome scaffold and the possibility that the scaffold is a preparative artifact are discussed.

scholarly journals Chromatinization ofEscherichia coliwith archaeal histones

2019 ◽  
Author(s):  
Maria Rojec ◽  
Antoine Hocher ◽  
Matthias Merkenschlager ◽  
Tobias Warnecke
Keyword(s):  
Nucleosome Occupancy ◽  
Micrococcal Nuclease ◽  
Ancestral State ◽  
E Coli ◽  
Genome Wide ◽  
Micrococcal Nuclease Digestion ◽  
Nuclease Digestion ◽  
Methanothermus Fervidus ◽  
Chromatin Proteins

ABSTRACTNucleosomes restrict DNA accessibility throughout eukaryotic genomes, with repercussions for replication, transcription, and other DNA-templated processes. How this globally restrictive organization emerged from a presumably more open ancestral state remains poorly understood. Here, to better understand the challenges associated with establishing globally restrictive chromatin, we express histones in a naïve bacterial system that has not evolved to deal with nucleosomal structures:Escherichia coli. We find that histone proteins from the archaeonMethanothermus fervidusassemble on theE. colichromosomein vivoand protect DNA from micrococcal nuclease digestion, allowing us to map binding footprints genome-wide. We provide evidence that nucleosome occupancy along theE. coligenome tracks intrinsic sequence preferences but is disturbed by ongoing transcription and replication. Notably, we show that higher nucleosome occupancy at promoters and across gene bodies is associated with lower transcript levels, consistent with local repressive effects. Surprisingly, however, this sudden enforced chromatinization has only mild repercussions for growth, suggesting that histones can become established as ubiquitous chromatin proteins without interfering critically with key DNA-templated processes. Our results have implications for the evolvability of transcriptional ground states and highlight chromatinization by archaeal histones as a potential avenue for controlling genome accessibility in synthetic prokaryotic systems.

scholarly journals Chromatinization of Escherichia coli with archaeal histones

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Maria Rojec ◽  
Antoine Hocher ◽  
Kathryn M Stevens ◽  
Matthias Merkenschlager ◽  
Tobias Warnecke
Keyword(s):  
Escherichia Coli ◽  
Nucleosome Occupancy ◽  
Micrococcal Nuclease ◽  
E Coli ◽  
Genome Wide ◽  
Micrococcal Nuclease Digestion ◽  
Nuclease Digestion ◽  
Methanothermus Fervidus ◽  
Chromatin Proteins

Nucleosomes restrict DNA accessibility throughout eukaryotic genomes, with repercussions for replication, transcription, and other DNA-templated processes. How this globally restrictive organization emerged during evolution remains poorly understood. Here, to better understand the challenges associated with establishing globally restrictive chromatin, we express histones in a naive system that has not evolved to deal with nucleosomal structures: Escherichia coli. We find that histone proteins from the archaeon Methanothermus fervidus assemble on the E. coli chromosome in vivo and protect DNA from micrococcal nuclease digestion, allowing us to map binding footprints genome-wide. We show that higher nucleosome occupancy at promoters is associated with lower transcript levels, consistent with local repressive effects. Surprisingly, however, this sudden enforced chromatinization has only mild repercussions for growth unless cells experience topological stress. Our results suggest that histones can become established as ubiquitous chromatin proteins without interfering critically with key DNA-templated processes.

scholarly journals Genome-wide SNPs Detect Fine-scale Genetic Structure in Threatened Populations of Squirrel Glider Petaurus Norfolcensis

2021 ◽  
Author(s):  
Monica Knipler ◽  
Mark Dowton ◽  
John Clulow ◽  
Ninon Meyer ◽  
Katarina M. Mikac
Keyword(s):  
Genetic Structure ◽  
Habitat Fragmentation ◽  
Dna Sequences ◽  
Nuclear Dna ◽  
Species Conservation ◽  
Population Declines ◽  
Least Cost Path ◽  
South Wales ◽  
Genome Wide ◽  
Squirrel Glider

Abstract Australian arboreal mammals are experiencing significant population declines, particularly due to land clearing and resulting habitat fragmentation. The squirrel glider, Petaurus norfolcensis, is a threatened species in New South Wales, with a stronghold population in the Lake Macquarie Local Government Area (LGA) where fragmentation due to urbanization is an ongoing problem for the species conservation. Here we report on the use of squirrel glider mitochondrial (385 bp cytochrome b gene, 70 individuals) and nuclear DNA (6,812 SNPs, 87 individuals) markers to assess their population genetic structure and connectivity across 14 locations sampled in the Lake Macquarie LGA. The mitochondrial DNA sequences detected evidence of a historical genetic bottleneck, while the genome-wide SNPs detected significant population structure in the Lake Macquarie squirrel glider populations at scales as fine as one kilometer. There was no evidence of inbreeding within patches, however there were clear effects of habitat fragmentation and biogeographical barriers on gene flow. A least cost path analysis identified thin linear corridors that have high priority for conservation. These areas should be protected to avoid further isolation of squirrel glider populations and the loss of genetic diversity through genetic drift.

scholarly journals DNA Methylation Differences Between Zona Pellucida-Bound and Manually Selected Spermatozoa Are Associated With Autism Susceptibility

2021 ◽  
Vol 12 ◽  
Author(s):  
Longda Wang ◽  
Mengxiang Chen ◽  
Gaofeng Yan ◽  
Shuhua Zhao
Keyword(s):  
Dna Methylation ◽  
Candidate Genes ◽  
Zona Pellucida ◽  
Chromatin Structure ◽  
Bisulfite Sequencing ◽  
Nuclear Dna ◽  
Selection Process ◽  
Biological Processes ◽  
Normal Morphology ◽  
Genome Wide

Children conceived through intracytoplasmic sperm injection (ICSI) have been reported to have a higher risk of many abnormalities and disorders, including autism and intellectual disability, which may be due to bypassing of the natural sperm selection process during ICSI. Zona pellucida (ZP)-bound spermatozoa (ZPBS) have normal morphology and nuclear DNA. Using these spermatozoa for ICSI results in better outcomes compared with conventional ICSI. However, differences besides morphology that exist between sperm selected by ZP and by an embryologist and whether these differences affect the risk of autism in offspring after ICSI are unclear. To explore these questions, we compared genome-wide DNA methylation profiles between ZPBS and manually selected spermatozoa (MSS)using single-cell bisulfite sequencing. Global DNA methylation levels were significantly lower in ZPBS than in MSS. Using gene ontology (GO) analysis, genes overlapping differentially methylated regions (DMRs) were enriched in biological processes involving neurogenesis. Furthermore, we found that 47.8% of autism candidate genes were associated with DMRs, compared with 37.1% of matched background genes (P<0.001). This was mainly because of the high proportion of autism candidate genes with bivalent chromatin structure. In conclusion, bivalent chromatin structure results in large differences in the methylation of autism genes between MSS and ZPBS. ICSI using MSS, which increases the risk of methylation mutations compared with ZPBS, may lead to a higher risk of autism in offspring.

Genome-Wide Analysis of Epistasis Using Multifactor Dimensionality Reduction

2011 ◽  
pp. 17-30 ◽  
Author(s):  
Jason H. Moore
Keyword(s):  
Dimensionality Reduction ◽  
Dna Sequences ◽  
Multifactor Dimensionality Reduction ◽  
Human Genetics ◽  
Interindividual Variation ◽  
Human Populations ◽  
Genome Wide Analysis ◽  
Genome Wide ◽  
Sequence Variations ◽  
Using Data

Human genetics is an evolving discipline that is being driven by rapid advances in technologies that make it possible to measure enormous quantities of genetic information. An important goal of human genetics is to understand the mapping relationship between interindividual variation in DNA sequences (i.e., the genome) and variability in disease susceptibility (i.e., the phenotype). The focus of the present study is the detection and characterization of nonlinear interactions among DNA sequence variations in human populations using data mining and machine learning methods. We first review the concept difficulty and then review a multifactor dimensionality reduction (MDR) approach that was developed specifically for this domain. We then present some ideas about how to scale the MDR approach to datasets with thousands of attributes (i.e., genome-wide analysis). Finally, we end with some ideas about how nonlinear genetic models might be statistically interpreted to facilitate making biological inferences.

scholarly journals Sequence-based prediction of single nucleosome positioning and genome-wide nucleosome occupancy

2012 ◽  
Vol 109 (38) ◽  
pp. E2514-E2522 ◽  
Author(s):  
Thijn van der Heijden ◽  
Joke J.F.A. van Vugt ◽  
Colin Logie ◽  
John van Noort
Keyword(s):  
Dna Sequences ◽  
Nucleosome Occupancy ◽  
Correlation Coefficients ◽  
Simple Algorithm ◽  
Nucleosome Positioning ◽  
Mechanics Model ◽  
Genome Wide ◽  
Sequence Effects

Nucleosome positioning dictates eukaryotic DNA compaction and access. To predict nucleosome positions in a statistical mechanics model, we exploited the knowledge that nucleosomes favor DNA sequences with specific periodically occurring dinucleotides. Our model is the first to capture both dyad position within a few base pairs, and free binding energy within 2 kBT, for all the known nucleosome positioning sequences. By applying Percus’s equation to the derived energy landscape, we isolate sequence effects on genome-wide nucleosome occupancy from other factors that may influence nucleosome positioning. For both in vitro and in vivo systems, three parameters suffice to predict nucleosome occupancy with correlation coefficients of respectively 0.74 and 0.66. As predicted, we find the largest deviations in vivo around transcription start sites. This relatively simple algorithm can be used to guide future studies on the influence of DNA sequence on chromatin organization.

Genome-Wide Epigenetics in Myeloid Leukemias.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. sci-35-sci-35
Author(s):  
Maria Eugenia Figueroa ◽  
John Greally ◽  
Ruud Delwel ◽  
Ari M. Melnick
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Chromatin Structure ◽  
Target Genes ◽  
Regulation Of Gene Expression ◽  
Promoter Hypermethylation ◽  
Genetic Alterations ◽  
Genome Wide ◽  
Myeloid Leukemias ◽  
Covalent Modifications

Abstract While the role of genetic alterations in cancer is well-recognized, epigenetic deregulation has only recently been identified as a hallmark of malignant transformation. The term “epigenetic” refers to a heritable regulation of gene expression that is not dependent on changes in the DNA sequence. These epigenetic modifications – including but not limited to DNA methylation and covalent modifications of histone tails – play a crucial role in determining chromatin structure and gene expression. Abnormal epigenetic regulation can lead to aberrant chromatin structure and deregulation of transcriptional activity. Epigenetic lesions can affect cancer-related genes, such as CDKN2B, CDKN2A, RB, and BRCA1, and it is not rare for epigenetic lesions to accompany genetic mutations of these and other genes, suggesting that epigenetic deregulation can form a part of the multi-step process of oncogenesis. An alteration in the distribution of DNA methylation has been demonstrated in AML as well as in other malignancies. Generally, intergenic DNA methylation is reported to decrease and promoter methylation to increase. Hypomethylation of DNA can lead to genomic instability and further increase the number of genetic lesions, while promoter hypermethylation has been associated with aberrant silencing of tumor suppressor genes. Altered levels of acetylation at specific histone residues were also shown to be associated with aberrant chromatin structure and gene deregulation in AML. Several oncogenic transcription factors and fusion proteins, such as PML-RARalpha, and AML1-ETO, can introduce aberrant epigenetic programming in myeloid cells through recruitment of epigenetic modifying enzymes to their target genes. However, the emerging field of epigenomic profiling has yielded evidence that epigenetic deregulation in AML is more profound and cannot always be linked to the presence of a given fusion protein. The mechanisms leading to genome-wide epigenetic deregulation still remain largely unidentified, although environmental factors and aging can contribute to this process. Current epigenetic profiling studies have revealed that DNA methylation or histone modification patterns can identify biologically distinct forms of AML that may not be readily identified through other methods. New data suggest that specific DNA methylation profiles may be associated with response to therapeutic agents, including epigenetic-targeted drugs. Numerous epigenetic candidate biomarkers have been recently described in both myeloid and lymphoid malignancies. Integrative analysis of DNA methylation, histone modifications, and gene expression may synergize to identify in far greater depth than single platform studies differences in gene regulation among leukemias. Overall, the emerging field of epigenomics provide a new opportunity to more accurately identify biological variation and therapeutically target acute myeloid leukemias.

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