DNA Methylation in Ctenophores.

Area of Science:

• Genomics
• Epigenetics
• Marine Biology

Background:

• DNA methylation is a key epigenomic regulator across species, influencing gene expression and evolution.
• Whole-genome bisulfite sequencing (WGBS) provides single-nucleotide resolution of DNA methylation patterns (methylomes).
• Existing WGBS protocols are optimized for vertebrates, with limited adaptation for invertebrates.

Purpose of the Study:

• To develop and optimize a library construction method for WGBS in non-bilateral metazoans, specifically the ctenophore Mnemiopsis leidyi.
• To enable comparative epigenomic studies between species by creating invertebrate methylome references.
• To investigate dynamic DNA methylation changes in response to stimuli.

Main Methods:

• Optimized bisulfite sequencing library construction for fragile marine invertebrates.
• Incorporated spike-in genomic DNA controls to accurately measure methylation conversion efficiency.
• Pooled bisulfite conversion reactions to increase sequencing library yield and unique mapping rates.

Main Results:

• Successfully detected 5-methylcytosine (5-mC) at CpG, CHG, and CHH sites in whole-animal methylomes.
• Visualized methylation data using circos diagrams.
• Observed changes in DNA methylation patterns of genes related to innexins, toxins, and neuropeptides under control and injury conditions.

Conclusions:

• The developed WGBS method is effective for generating high-quality methylomes from non-bilateral metazoans.
• This approach facilitates the study of epigenomic regulation in diverse and fragile marine organisms.
• The method can be readily adapted for epigenome production in other marine invertebrates.