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Global DNA methylation loss associated with mercury contamination and aging in the American alligator (Alligator mississippiensis)



Frances Nilsen, John Bowden, Brittany L. Kassim, Colleen E. Bryan Sallee, Stephen E. Long, Benjamin B. Parrott, Stephen E. Somerville, Ted Lange, Patrick Delaney, Arnold Brunell, Louis J. Guillette


Mercury is a widespread environmental contaminant with exposures eliciting a well-documented catalog of negative outcomes in animals. Yet, our knowledge regarding the underlying mechanisms by which mercury exposures exert these effects remains incomplete. DNA methylation is a fundamental epigenetic modification known to be responsive to environmental cues, and decreases in DNA methylation at the global level are associated with a variety of diseases. Here, using a mass spectrometric approach, we examine global DNA methylation levels across a large number of long-lived, apex predators from sites contaminated with highly variable amounts of mercury. We quantify mercury levels in these animals and consistent with other studies show that mercury levels appear higher in those animals residing in more southern Florida sites. Further, we demonstrate that global DNA methylation loss is inversely correlated to increasing concentrations of mercury in the environment. The relationship between age-associated changes in global DNA methylation and mercury levels is probed, and a potential link between environmental exposures and aging is discovered. These findings provide valuable insights into interactions between the epigenome and environment in long-lived organisms undergoing chronic exposures.
Science of the Total Environment


DNA methylation, mercury, American alligator, aging, environmental contaminants, liquid chromatography tandem mass spectrometry, deoxyribonucleoside


Nilsen, F. , Bowden, J. , Kassim, B. , Bryan, C. , Long, S. , Parrott, B. , Somerville, S. , Lange, T. , Delaney, P. , Brunell, A. and Guillette, L. (2016), Global DNA methylation loss associated with mercury contamination and aging in the American alligator (Alligator mississippiensis), Science of the Total Environment, [online], (Accessed June 23, 2024)


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Created March 1, 2016, Updated November 10, 2018