Most of us know the term, DNA, but unless you are involved in some aspect of the scientific or medical world, it’s unlikely to be a subject that you discuss very often. However when you conceive, it may be a topic that naturally becomes more interesting for you. This article investigates pregnancy and DNA: it looks at what DNA is, what happens with a developing fetus during pregnancy, in terms of his/her DNA, along with the importance of nutrition.
What is DNA?
DNA is the abbreviation for deoxyribonucleic acid. Essentially a baby’s DNA is what makes them the girl or boy they turn out to be. DNA is the genetic code which makes the characteristics of any living being. Your baby, just like you did from your parents, will get his DNA from you and your partner. This inherited DNA can be referred to as hereditary material, as it is a body of information that is passed down from generation to generation. No one else has the same DNA as you, that is unless you happen to be an identical twin!
Shaped as a double helix, deoxyribonucleic acid is a big molecule, which consists of repeating units, known as nucleotides. Each of these contains a phosphate molecule and sugar, along with one of four organic bases, which together are like the backbone of DNA. What determines a person’s characteristics are the order of these organic bases within the molecule. These bases are adenine (A), guanine (G), cytosine (C) and thymine (T)
Pregnancy and DNA
This hereditary material, DNA, is actually passed onto the embryo at the moment of conception. Numerous features are determined at this time, such as blood type and eye colour. The process actually starts during fertilisation, at which stage the parents’ genetic codes undergo a bonding process. These bonded genes then become arranged in chains, not unlike a string of pearls.
As the fetus develops, each time one of his cells splits, the cell creates an identical copy of itself in all cells. This chain of codes is a fascinating subject, yet it is one that scientists have yet to discover more about. What is known, however, is that while DNA predetermines many aspects of humans, these genetic code combinations are also influenced by both the fetus’ environment, and continue to be influenced and formed after birth.
Medical studies link DNA methylation and early nutrition
Following on from the concept that some of your unborn baby’s genetic code can be influenced by his “environment”, which is at that stage your womb, along with the nutrtion he receives from you, then it is logical to consider what can potentially help his development. Medical studies have linked a process called DNA methylation and early nutrition together, to either improve or disimprove a fetus’ outcomes, in terms of health.
To get the jargon out of the way first, DNA methylation is a common epigenetic signalling tool that cells use to lock genes in the “off” position. For a number of decades now, scientific researchers have been studying DNA methylation and have learnt a great deal about it. They have discovered that DNA methylation is a very important component in many cellular processes, which include embryonic development, X-chromosome inactivation, genomic imprinting and preservation of chromosome stability. (3)
There is still lots of research that needs to be done on this topic, and although a great deal of methylation occurs at the very earliest stages just after conception, it is a continual process, just to a lesser degree, according to current research.
University of Utah Genetics Faculty Synopsis
The Genetics Faculty of the University of Utah has done a good job of compiling this information, in a relatively easy to digest manner, which you can read below. At the end of this article, we also link to our feature about folic acid, due to its important role in all of this.
Nutrition & the Epigenome
Unlike behaviour or stress, diet is one of the more easily studied, and therefore better understood, environmental factors in epigenetic change. The nutrients we extract from food enter metabolic pathways where they are manipulated, modified, and molded into molecules the body can use. One such pathway is responsible for making methyl groups – important epigenetic tags that silence genes.
Familiar nutrients like folic acid, B vitamins, and SAM-e (S-Adenosyl methionine, a popular over-the-counter supplement) are key components of this methyl-making pathway. Diets high in these methyl-donating nutrients can rapidly alter gene expression, especially during early development when the epigenome is first being established.
Let’s take a detailed look at the nutrients that affect our epigenome and the foods they come from.
Nutrients from our food are funneled into a biochemical pathway that extracts methyl groups and then attaches them to our DNA. Diet during early development can have long-lasting effects
Your mother’s diet during pregnancy and your diet as an infant can affect your epigenome in ways that stick with you into adulthood. Animal studies have shown that a diet with too little methyl-donating folate or choline before or just after birth causes certain regions of the genome to be under-methylated for life. For adults too, a methyl-deficient diet leads to a decrease in DNA methylation, but the changes are reversible when methyl is added back to diet.
Eating For Two
Experiments in mice show just how important a mother’s diet is in shaping the epigenome of her offspring. All mammals have a gene called agouti. When a mouse’s agouti gene is completely unmethylated, its coat is yellow and it is obese and prone to diabetes and cancer. When the agouti gene is methylated (as it is in normal mice), the coat colour is brown and the mouse has a low disease risk. Fat yellow mice and skinny brown mice are genetically identical. The fat yellow mice are different because they have an epigenetic “mutation.”
When researchers fed pregnant yellow mice a methyl-rich diet, most of her pups were brown and stayed healthy for life. These results show that the environment in the womb influences adult health. In other words, our health is not only determined by what we eat, but also what our parents ate.
Of Toxins and Supplements
Chemicals that enter our bodies can also affect the epigenome. Bisphenol A (BPA) is a compound used to make polycarbonate plastic. It is in many consumer products, including water bottles and tin cans. Controversial reports questioning the safety of BPA came out in 2008, prompting some manufacturers to stop using the chemical.
In the laboratory, BPA appears to reduced methylation of the agouti gene. In the strain of mice that was studied, yellow mothers give birth to pups with a range of coat colors from yellow to brown. When mothers were fed BPA, their babies were more likely to be yellow and obese..
However, when mothers were fed BPA along with methyl-rich foods, the offspring were more likely to be brown and healthy. The maternal nutrient supplementation had counteracted the negative effects of exposure.
Don’t Count Dad Out
So if a pregnant mother’s diet can affect the child’s epigenetic outcome, can Dad’s diet do the same? Quite possibly, according to scientists who delved into the well-kept, historical records of annual harvests from a small Swedish community.
These records showed that food availability between the ages of nine and twelve for the paternal grandfather affected the lifespan of his grandchildren. But not in the way you might think.
Shortage of food for the grandfather was associated with extended lifespan of his grandchildren. Food abundance, on the other hand, was associated with a greatly shortened lifespan of the grandchildren. Early death was the result of either diabetes or heart disease. Could it be that during this critical period of development for the grandfather, epigenetic mechanisms are “capturing” nutritional information about the environment to pass on to the next generation?
Food abundance for the grandfather was associated with a reduced lifespan for his grandchildren.
The Emerging Field of Nutrigenomics
As we better understand the connections between diet and the epigenome, the opportunity arises for clinical applications. Just as mapping our gene variations gives us a window into our personalized medical needs, so might a profile of one’s unique epigenome.
Formed through a lifetime of experiences beginning in the womb, our epigenome may provide a wealth of information about how to eat better. Enter the future field of nutrigenomics, where nutritionists take a look at your methylation pattern and design a personalised nutrition plan. While we’re not quite to that point yet, your doctor can already tell a lot about the your disease risk by looking at your family health history.
A Bee’s Royal Diet
Royal jelly is a complex, protein-rich substance secreted from glands on the heads of worker bees. A larva destined to become a queen is fed large amounts of royal jelly inside a compartment called a queen cup.
The larvae that develop into workers and queens are genetically identical. But because of her royal jelly diet, the queen will develop ovaries and a larger abdomen for egg laying, while the worker will be sterile. She’ll also develop queenly behaviours: the instincts to kill rival queens, make communication sounds known as “piping,” and go on “mating flights.” The queen is fed only royal jelly for her entire life.
In a series of experiments, scientists determined that royal jelly silences a key gene (Dnmt3), which codes for an enzyme that silences a group of queen genes. When Dnmt3 is turned “on,” the queen genes are epigenetically silenced, and the larvae develop into the default “worker” variety. But when royal jelly turns Dnmt3 “off,” the queen genes jump into action, turning the larvae into queens.
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