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Influence of tissue, age, and environmental quality on global levels of genomic methylation in the American alligator (Alligator mississippiensis)



Benjamin B. Parrott, John Bowden, Satomi Kohno, Jessica A. Cloy-McCoy, Jacqueline T. Bangma, Thomas R. Rainwater, Phillip M. Wilkinson, John Kucklick, Louis J. Guillette


Epigenetic modifications are key mediators of the interactions between the environment and an organism's genome. DNA methylation represents the best-studied epigenetic modification to date and is known to play key roles in regulating transcriptional activity and promoting chromosome stability. Our lab has previously demonstrated the utility of the American alligator (Alligator mississippiensis) as a sentinel species to investigate the persistent effects of environmental contaminant exposure on reproductive health. Here, we incorporate a liquid chromatography-tandem mass spectrophotometry method to directly measure the total (global) proportion of 5-methyl-2′-deoxycytidine (5mdC) in ovarian and blood DNA from alligators. Global DNA methylation in ovaries was found to be significantly elevated when compared to that of blood. However, DNA methylation appeared similar in juvenile alligators reared under controlled laboratory conditions but originating from three sites with dissimilar environmental qualities, indicating an absence of detectable site-of-origin effects on persistent levels of global 5mdC content. Analyses of tissues across individuals revealed a surprising lack of correlation between global methylation levels in blood and ovary. In addition, global DNA methylation in blood samples from juvenile alligators was elevated when compared to those from adults, suggesting that age, as observed in mammals, may negatively influence global DNA methylation levels in alligators. To our knowledge, this is the first study examining global levels of DNA methylation in the American alligator and provides a reference point for future studies examining the interplay of epigenetics and environmental factors in a long-lived sentinel species.
PLoS One


Global DNA Methylation, Liquid Chromatography Tandem Mass Spectrometry, Nucleosides


Parrott, B. , Bowden, J. , Kohno, S. , Cloy-McCoy, J. , Bangma, J. , Rainwater, T. , Wilkinson, P. , Kucklick, J. and Guillette, L. (2014), Influence of tissue, age, and environmental quality on global levels of genomic methylation in the American alligator (Alligator mississippiensis), PLoS One, [online],, (Accessed July 13, 2024)


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Created January 6, 2014, Updated October 12, 2021