Effect of Hypoxia on DNA Methylation during Early Embryonic Development of Atlantic Killifish (Fundulus heteroclitus)

Science Center, Bent Corridor

Hypoxia, or insufficient oxygen availability, is a common phenomenon that occurs in coastal aquatic environments. With climate change the number of hypoxic areas, called dead zones, are increasing due to rising global temperatures. This puts marine organisms at risk if they cannot adapt to the changing environmental conditions induced by humans. Most organisms have a short term protective hypoxia-inducible factor (HIF) signaling system to adjust their metabolism in response to low oxygen stress. Studies have shown that cellular responses to hypoxia in the signaling system involve epigenetic modifications; however, little is known on this effect during embryonic development. The aim of this study was to investigate the role of epigenetic modifications in physiological responses to short term hypoxia in Atlantic Killifish. There were three experimental treatments (20% O 2 , 5% O 2 , and 1% O 2 ) and an outside control. A Quantitative PCR assay was performed to quantify expression of hypoxia responsive genes, DNA methyltransferases and DNA demethylases in response to the experimental treatments. In addition, we conducted a slot blot assay to characterize global DNA methylation and hydroxymethylation profiles during embryonic development in response to the experimental treatments. We concluded that hypoxia affected DNA methyltransferases and demethylases gene expression; however, significant impacts among global methylation and hydroxymethylation patterns were not observed. Future studies will be conducted to determine hypoxia responsive genes in early embryos by RNA-seq and quantify gene-specific or genome-wide methylation profiles. Understanding short term responses to hypoxia will help to clarify the relationship between hypoxia and DNA methylation during embryonic development, while addressing the possible mechanism that may aid adaptation in the future.