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The methylome of Drosophila melanogaster

ABSTRACT: Cytosine methylation in the genome of Drosophila melanogaster has been elusive and controversial: methylcytosine has been detected at very low levels in early embryos, but the genomic location and function of methylation has not been established. We have mapped cytosine methylation genomewide in Stage 5 Drosophila embryo DNA by combining immuno-enrichment for 5-methylcytosine, bisulfite conversion, and deep sequencing. Unlike methylation patterns observed in other eukaryotic species, methylation in Drosophila is punctate and highly strand-asymmetrical; we confirmed this by direct PCR amplification and sequencing of bisulfite-converted DNA. Despite the locally asymmetric nature of methylation, large-scale patterns of methylation are symmetric. Methylated regions make up ~1% of the genome, and within these regions methylation of individual cytosines averages 2-10%. Methylation is concentrated in specific 5-base sequence motifs that are CA- and CT-rich but depleted of guanine. It is depleted from promoters, coding sequences, and most retrotransposons, and enriched in introns and in certain simple sequence repeats containing the commonly methylated motifs. Comparison with available gene expression data indicates that methylation in a gene is associated with lower expression; the X chromosome, which is subject to gene dosage compensation, is more densely methylated than the autosomes. This study firmly establishes the presence of cytosine methylation in Drosophila; the temporal overlap of methylation with the maternal-zygotic transition raises the possibility that methylation participates in the transition to zygotic gene expression.

ORGANISM(S): Lambdavirus lambda Drosophila melanogaster

PROVIDER: GSE34425 | GEO | 2014/02/18

SECONDARY ACCESSION(S): PRJNA149555

REPOSITORIES: GEO

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Project description:Cytosine methylation in the genome of Drosophila melanogaster has been elusive and controversial: methylcytosine has been detected at very low levels in early embryos, but the genomic location and function of methylation has not been established. We have mapped cytosine methylation genomewide in Stage 5 Drosophila embryo DNA by combining immuno-enrichment for 5-methylcytosine, bisulfite conversion, and deep sequencing. Unlike methylation patterns observed in other eukaryotic species, methylation in Drosophila is punctate and highly strand-asymmetrical; we confirmed this by direct PCR amplification and sequencing of bisulfite-converted DNA. Despite the locally asymmetric nature of methylation, large-scale patterns of methylation are symmetric. Methylated regions make up ~1% of the genome, and within these regions methylation of individual cytosines averages 2-10%. Methylation is concentrated in specific 5-base sequence motifs that are CA- and CT-rich but depleted of guanine. It is depleted from promoters, coding sequences, and most retrotransposons, and enriched in introns and in certain simple sequence repeats containing the commonly methylated motifs. Comparison with available gene expression data indicates that methylation in a gene is associated with lower expression; the X chromosome, which is subject to gene dosage compensation, is more densely methylated than the autosomes. This study firmly establishes the presence of cytosine methylation in Drosophila; the temporal overlap of methylation with the maternal-zygotic transition raises the possibility that methylation participates in the transition to zygotic gene expression. To enrich for rare cytosine methylation in Drosophila at embryonic Stage 5 (2-3 hours post-fertilization), we enriched sonicated Stage 5 genomic DNA for methylcytosine by immunoprecipitation with antibody to 5-methylcytosine. The immunoprecipitated DNA was then bisulfite converted and Illumina sequenced to obtain direct evidence for the presence of methylation. The presence and extent of DNA methylation was confirmed by Illumina sequencing of bisulfite-converted PCR amplicons.

Project description:Whole genome shotgun bisulfite sequencing, small RNA sequencing and transcriptome sequencing of wildtype Arabidopsis plants (Col-0), and met1, drm1 drm2 cmt3, and ros1 dml2 dml3 null mutants using the Illumina Genetic Analyzer. A comparison was performed with regions of the genome containing cytosine DNA methylation identified by methylcytosine immunoprecipitation and whole-genome oligonucleotide tiling microarrays, for wildtype Col-0. Understanding the epigenetic regulatory mechanisms that mediate control of transcription at multiple levels is critical to understanding how plants develop and respond to their environment. We combined next-generation sequencing by synthesis (SBS) technology with novel methods for direct sequencing of the entire cytosine methylome (methylC-seq), transcriptome (RNA-seq), and the small RNA component of the transcriptome (smRNA-seq) to create a set of highly integrated epigenome maps for Arabidopsis thaliana, in conjunction with a set of informative mutants defective in DNA methyltransferase and DNA demethylase activity. At single-base resolution we discovered extensive, previously undetected, DNA methylation, identified the context and level of methylation at each site, and found that local composition has effects upon DNA methylation state. Deep sequencing of the smRNAome exposed a direct relationship between the location and abundance of smRNAs and DNA methylation, perturbation of smRNA biogenesis upon loss of CpG DNA methylation, and a tendency for smRNAs to direct strand-specific DNA methylation in the region of RNA-DNA homology. Finally, strand-specific RNA-seq revealed changes in the transcript abundance of hundreds of genes upon alteration of the DNA methylation state, and enabled the identification of numerous previously unidentified genes regulated by DNA methylation. Keywords: Whole genome shotgun bisulfite sequencing, small RNA sequencing, transcriptome sequencing, methylcytosine immunoprecipitation, whole-genome oligonucleotide tiling microarrays Whole genome shotgun bisulfite sequencing, small RNA sequencing and transcriptome sequencing of wildtype Arabidopsis plants (Col-0), and met1, drm1 drm2 cmt3, and ros1 dml2 dml3 null mutants using the Illumina Genetic Analyzer. A comparison was performed with regions of the genome containing cytosine DNA methylation identified by methylcytosine immunoprecipitation and whole-genome oligonucleotide tiling microarrays, for wildtype Col-0.

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The methylome of Drosophila melanogaster

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