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SRX21542006: GSM7746907: L528-IgG; Homo sapiens; Breviolum minutum; MeDIP-Seq
1 ILLUMINA (NextSeq 550) run: 2.7M spots, 220.8M bases, 92.8Mb downloads

External Id: GSM7746907_r1
Submitted by: Genetics, Stanford University
Study: Genome-wide distribution of 5-hydroxymethyluracil and chromatin accessibility in the Breviolum minutum genome
show Abstracthide Abstract
In dinoflagellates, the most unique and divergent nuclear organization among the known diversity of eukaryotes has evolved. The list of highly unusual features of dinoflagellate nuclei and genomes is long -- permanently condensed liquid crystalline chromosomes, in which histones are not the main packaging component, genes organized as very long unidirectional gene arrays, general absence of transcriptional regulation, high abundance of the otherwise very rare DNA modification 5-hydroxymethyluracil (5-hmU), and many others. Most of these fascinating properties were originally identified in the 1970s and 1980s but have received very little attention in recent decades using modern genomic tools. In this work, we address some of the outstanding questions regarding dinoflagellate genome organization by mapping the genome-wide distribution of 5-hmU (using both immunoprecipitation-based and basepair-resolution chemical mapping approaches) and of chromatin accessibility in the genome of the dinoflagellate Breviolum minutum. We find that the 5-hmU modification is preferentially enriched over certain classes of repetitive elements, and also often coincides with the boundaries between gene arrays. It is generally anti-correlated with chromatin accessibility, the levels of which are lower in those regions. We discuss the potential roles of 5-hmU in the functional organization of dinoflagellate genomes and its relationship to the transcriptional landscape of gene arrays. Overall design: ATAC-seq in B. minutum; mapping of 5-hmU in B. minutum using MeDIP-seq and chemical mapping; SMF and ATAC-seq on yeast cells exogenously expressing various dinoflagellate DVNP proteins
Sample: L528-IgG
SAMN37205253 • SRS18751405 • All experiments • All runs
Organism: Homo sapiens
Library:
Name: GSM7746907
Instrument: NextSeq 550
Strategy: MeDIP-Seq
Source: GENOMIC
Selection: 5-methylcytidine antibody
Layout: PAIRED
Construction protocol: B. minutum genomic DNA was isolated as follows. Briefly, cells were centrifuged at 1,000 g for 5 minutes, then resuspended in 500 µL 1× Cell Lysis Buffer (prepared by mixing equal volumes of 2× Cell Lysis Buffer – 2% SDS, 400 mM NaCl, 40 mM EDTA, 100 mM Tris-HCl, pH 8.0 – and H2O) and vortexed. The lysed cells were mixed with an equal 500 µL volume Phenol:Chloroform:Isoamyl alcohol (25:24:1), and mixed well by inverting a few times. The phases were centrifugation at 13,000 g for 5 minutes, then the top phase was transferred to a new tube and treated with 4 µL Ribonuclease A (20 mg/mL) by incubating for 30 minutes at 37◦C. DNA was purified by adding an equal volume Phenol:Chloroform:Isoamyl alcohol (25:24:1), mixing well and centrifuging at 13,000 g for 5 minutes, then transferring the top layer to a new tube, to which Phenol:Chloroform:Isoamyl alcohol (25:24:1) was added again, and the centrifugation and top phase isolation was repeated. Then 2.5× volumes of 100% EtOH were added and the mixture was incubated on ice for 30 minutes or at -20◦C overnight. The solution was then centrifuged at 13,000 g at room temperature for 20 minutes, the pellet was washed with 70% EtOH, dried on air and resuspended in 50 µL H2O. To prepare inputs for MeDIP-seq experiments, gDNA was first sonicated using a Qsonica S-4000 with a 1/16” tip for 3 minutes, with 10 second pulses at intensity 3.5, and 20 seconds rest between pulses. For each reaction, 100 µL of Protein A Dynabeads (ThermoFisher Cat # 10002D) were washed 3 times with a 5 mg/mL BSA solution. Beads were then resuspended in 1 mL BSA solution and 5 µL of α-5-hmU antibody (Abcam Cat # ab19735) were added. Coupling of antibodies to beads was carried out overnight on a rotator at 4◦C. Beads were again washed 3 times with BSA solution and resuspended in 100 µL of BSA solution. Sheared genomic DNA (∼1 µg 1:1 mix of B. minutum and Homo sapiens) was end repaired and adapters were ligated to it following the procedure of the NEBNext Ultra II DNA Library Prep Kit for Illumina (NEB, E7645S), purified using AMPure XP beads and eluted in 50 µL of H2O, and then denatured at 98◦C for 10 minutes. DNA was then immediately placed on ice, resuspended in 850 µL RIPA buffer (1× PBS, 1% IGEPAL, 0.5% Sodium Deoxycholate, 0.1% SDS, Roche Protease Inhibitor Cocktail) and added to the beads, then incubated overnight on a rotator at 4◦C. Beads were washed 5 times with LiCl buffer (10 mM Tris-HCl pH 7.5, 500 mM LiCl, 1% NP-40/IGEPAL, 0.5% Sodium Deoxycholate) by incubating for 10 minutes at 4◦C on a rotator, then rinsed once with 1× TE buffer. Beads were then resuspended in 200 µL IP Elution Buffer (1% SDS, 0.1 M NaHCO3) and incubated at 65◦C in a Thermomixer (Eppendorf) with interval mixing to dissociate antibodies. Beads were separated from the DNA solution by centrifugation, and DNA was purified using the MinElute kit. Library generation was completed by carrying out PCR following the rest of the steps of the NEBNext Ultra II DNA Library Prep Kit protocol, using 15 cycles of amplification. Final libraries were purified using AMPure XP beads.
Runs: 1 run, 2.7M spots, 220.8M bases, 92.8Mb
Run# of Spots# of BasesSizePublished
SRR258202552,745,934220.8M92.8Mb2023-10-19

ID:
29025648

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