Predominant intragenic methylation is associated with gene expression characteristics in a bivalve mollusc.

PeerJ. 2013;1:e215

Authors: Gavery MR, Roberts SB

Abstract
Characterization of DNA methylation patterns in the Pacific oyster, Crassostrea gigas, indicates that this epigenetic mechanism plays an important functional role in gene regulation and may be involved in the regulation of developmental processes and environmental responses. However, previous studies have been limited to in silico analyses or characterization of DNA methylation at the single gene level. Here, we have employed a genome-wide approach to gain insight into how DNA methylation supports the regulation of the genome in C. gigas. Using a combination of methylation enrichment and high-throughput bisulfite sequencing, we have been able to map methylation at over 2.5 million individual CpG loci. This is the first high-resolution methylome generated for a molluscan species. Results indicate that methylation varies spatially across the genome with a majority of the methylated sites mapping to intra genic regions. The bisulfite sequencing data was combined with RNA-seq data to examine genome-wide relationships between gene body methylation and gene expression, where it was shown that methylated genes are associated with high transcript abundance and low variation in expression between tissue types. The combined data suggest DNA methylation plays a complex role in regulating genome activity in bivalves.

PMID: 24282674 [PubMed – as supplied by publisher]

via pubmed: school of aquatic an… http://www.ncbi.nlm.nih.gov/pubmed/24282674?dopt=Abstract

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Characterizing short read sequencing for gene discovery and RNA-Seq analysis in Crassostrea gigas.

Comp Biochem Physiol Part D Genomics Proteomics. 2012 Jun;7(2):94-9

Authors: Gavery MR, Roberts SB

Abstract
Advances in DNA sequencing technology have provided opportunities to produce new transcriptomic resources for species that lack completely sequenced genomes. However, there are limited examples that rely solely on ultra-short read sequencing technologies (e.g. Solexa, SOLiD) for transcript discovery and gene expression analysis (i.e. RNA-Seq). Here we use SOLiD sequencing to examine gene expression patterns in Pacific oyster (Crassostrea gigas) populations exposed to varying degrees of anthropogenic impact. Novel transcripts were identified and RNA-Seq analysis revealed several hundred differentially expressed genes. Gene enrichment analysis determined that in addition to biological processes predicted to be associated with anthropogenic influences (e.g. immune response), other processes play important roles including cell recognition and cell adhesion. To evaluate the effectiveness of restricting characterization solely to short read sequences, mapping and RNA-Seq analysis were also performed using publicly available transcriptome sequence data as a scaffold. This study demonstrates that ultra-short read sequencing technologies can effectively generate novel transcriptome information, identify differentially expressed genes, and will be important for examining environmental physiology of non-model organisms.

PMID: 22244882 [PubMed – indexed for MEDLINE]

via pubmed: school of aquatic an… http://www.ncbi.nlm.nih.gov/PubMed/22244882?dopt=Abstract