Prolonged Fasting Increases DNA Methylation in Northern Elephant Seal Pups

Abstract

Northern elephant seals (NES) are naturally exposed to extreme conditions, including prolonged food and water deprivation (fasting). NES pups initially nurse for a month before they are weaned and fast for two months. During this fasting period NES pups lose about 25% of their body mass, while maintaining biochemical homeostasis and supporting muscle development. The environment, especially stressful environmental conditions, can modify the methylation status of DNA, consequently regulating gene expression. We compared global DNA methylation between early (1–2 weeks) and late (7–8 weeks) fasting NES pups. DNA was extracted from white blood cells collected from fasting NES pups. Global DNA methylation was measured using a MethylFlash™ Global DNA Methylation (5‐mC) Kit. Prolonged fasting significantly increased global DNA methylation (p = 0.0463) in NES pups, suggesting a decrease in transcription activity. We are in the process of identifying changes in specific genes involved in growth, hypoxia tolerance, and metabolism between early and late fasting pups by analyzing the methylation status of CpG islands in putative promoter region sequences. Our initial results suggest that DNA methylation is an important regulator of gene expression during natural, prolonged food deprivation.