Obesity and Epigenetics

Our genome holds the information that makes us individuals, so how can a small mouse and an obese mouse have vastly different phenotypes when they are genetically identical? For these mice the difference lies in their epigenomes, which can drastically modify the expression of genes and associated phenotypes through regulation. The gene responsible for the obesity in mice also results in differences in coat color, which emphasized the likelihood that these changes in phenotype had a single genetic origin. Randy Jirtle tested a suspected environmental trigger, bisphenol A, by exposing it to pregnant mice and found that DNA methylation across multiple sites but especially around the agouti gene site by 31%. The agouti gene is responsible for determining coat color and similar receptors have been found in areas of the brain that are associated with feeding behavior and body weight (Lu et al, 1994). Although there was public cause for alarm due to bisphenol A being found in a large variety of everyday items Jirtle also found that its effects can also be minimized or avoided through supplementing the mothers’ diet with methyl inducing substances.  This experiment gives us a succinct story regarding the interactions of "Nature vs Nurture" with obvious real world effects and methods to use in order to improve health.

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