Genetic Imprinting: Unborn Babies Use Gene From Dad to Trick Mom's Body, Divert Nutrients to Fetus
Unborn babies inherit a gene from their dads to help them survive during their development. According to a new study, this gene tricks the mom's body to deliver more nutrients to the growing fetus.
Gene Inherited From Dads Tricks Moms to Deliver More Nutrients to Growing Fetus
Researchers discovered that mouse babies steal nutrients from their mother through the placenta by copying an imprinted gene inherited from their father.
It's the first concrete proof that a gene passed down from the father tells the mother to focus nutrients on the fetus, claims research co-author and reproductive biologist Amanda Sferruzzi-Perri of the University of Cambridge, ScienceAlert reported.
The genes a baby receives tend to stimulate fetal growth, while those from the mother inhibit it. Even when pregnant, a mother must care for herself to nourish her unborn child.
Although most pregnancies are cooperative, co-senior author Miguel Constancia, an epigeneticist at the University of California, Berkeley, says there is much room for possible conflict between the mother and the child.
According to Constancia, the nutritional "tug-of-war" that is pregnancy is thought to be mostly influenced by genetic imprinting and hormones released in the placenta.
Scientists hypothesized that embryos had evolved covert mechanisms to meet their nutritional needs, much like moms had preserved their own. The hormone-insulin-like growth factor 1 (Igf2) was even the focus of research, with the statement "powerful effects of fetal growth" made.
However, the precise mechanisms remained unknown: the placenta, where Igf2 and many other hormones are created and function, "is arguably the most important organ of the body, but paradoxically the most poorly understood," according to a 2015 study.
Jorge Lopez-Tello, a physiologist at the University of Cambridge, worked with colleagues to manipulate the gene encoding Igf2, similar to the hormone insulin, in a series of animal tests.
Pregnant moms develop insulin resistance in the later stages of pregnancy to prevent their cells from absorbing the nutrition their unborn children require. Insulin is a hormone that aids cells in absorbing glucose from the blood.
The mice studies demonstrated that Igf2, produced in placental cells, increases a pregnant mother's resistance to insulin, which causes more glucose to be transferred to the fetus.
This means that nutrients are more readily available in the blood to be delivered to the fetus because the mother's tissues don't absorb glucose, according to Sferruzzi-Perri.
We were unaware until recently that the Igf2 gene also controls the signals sent to the mother so she can distribute nutrients to the fetus, she added.
Mice that did not have a functional copy of the Igf2 gene from their father in placental cells were smaller at birth because their mother did not provide enough nutrition.
The study was published in Cell Metabolism.
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What Is Genetic Imprinting?
Genetic imprinting is a relatively perplexing phenomenon that has gained some understanding recently. In essence, it refers to a DNA sequence being chemically altered. Remember that the DNA sequence itself is not altering at this point. These are alterations to the DNA sequence that occur in a cell-typically a germ cell, such as an egg or sperm cell-and, are handed down from one generation to the next, per National Human Genome Research Institute. Because it lacks a sequence-based method of inheritance, it perplexed scientists for a long time. It was first believed that all inheritance is based on changes in sequence. However, this has now been shown to be false.
Imprinting refers to one of those methods, which is not concerned with sequence change but rather an inherited chemical modification to a DNA sequence.
The reason that imprinting is crucial is that chemical modifications, which are transferred from the mother or the father to the children, alter the function of the gene or the gene product, whether they affect how the gene is expressed or the function of the gene product itself.
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