Written by Anon
Maternal nutrition, especially in the early stages of the embryo’s development, can suppress the expression of active genes that may be harmful to the organism. Certain compounds in maternal vitamins do not alter the embryo's DNA, but can change the phenotype of a gene. According to the thrifty phenotype hypothesis, fetuses that experience a lack of nutrition develop a slower metabolism as an adaptive response to the nutrient deficient environment. The results of recent studies further emphasize the importance of maternal nutrition. In a Duke study, a pregnant group of mice with an active agouti gene were given prenatal vitamin supplements. Unlike the control group, the treated group gave birth to thin brown mice. Some of the compounds in the vitamin turned off the agouti gene in the mice’s embryos. Though their DNA was not altered, and they still had this gene, but the expression of this gene was altered.
Nutrition isn’t the only factor that can affect the gene expression of an embryo. What the mother senses and experiences in her environment sends signals to the developing genome, turning some genes on and off. This maternal effect, or predictive adaptive response, usually works well within the first week of conception when it comes to human epigenetics. Many animals have offspring suited to its environment through maternal signals; for example, if the mother freshwater flea Daphnia senses that there are many predators in the environment, she will have offspring with bigger spines and helmets.
Parental care, the “nurture” side of the “nature v nature” debate, also plays a role in epigenetic changes. The placement of methyl markers, markers that determine whether a gene shows completely, partially, or not at all, can also be placed and removed after birth. Michael Meaney conducted a study in which he placed genetically aloof pups with adoptive genetically caring parent mice. The loving mice’s affection removed methyl markers in the pups’ brains, further developing “the part of the brain that dampened the stress response” (Moalem 169). In other words, despite the pups’ genetics, they grew to be stable-minded mice because of the effect of parental care on their methyl markers.
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