User:Boydak13/Environmental Epigenetics - Nutrition

Overview
Epigenetics is the study of how outside factors can influence the expression of certain genes to create a variation of phenotypes (physical attributes/characteristics) without affecting the organism's DNA. The base pair nucleotides (Adenine, Thymine, Guanine, and Cytosine) pair together to form DNA structures. The environment can change how many organisms such as plants, animals, bacteria, and even humans, develop and continue to grow. The three environmental agents that can cause phenotypes to be altered, including Direct Transcriptional Regulation, Neuroendocrine system, and Direct Induction. The most influential factors that affect environmental epigenetics are behaviors, nutrition, and chemical exposure.

Nutrition is one of the factors that most commonly affects organisms, especially humans. The development of a fetus, especially during utero, is heavily affected by the mother's intake of nutrients. The nervous system receives signals from the environment to release chemical signals, altering the hormone production within organisms. The production of these hormones then causes changes in the phenotype of the animal.

Mechanisms of Epigenetics
The main mechanisms of epigenetics include, DNA Methylation, Histone Modifications, and Non-coding RNAs. DNA Methylation occurs when a methyl group is added to a DNA cytosine base; this usually happens at CpG sites. Because methylation patterns change DNA's accessibility to transcription factors and other regulatory proteins, they can affect how genes are expressed. Proteins called histones wrap DNA to form chromatin. Histone tails can undergo a variety of chemical modifications, including acetylation, methylation, phosphorylation, and ubiquitination, which can affect chromatin structure and gene expression. Non-coding RNA molecules regulate the expression of genes but do not encode proteins. Examples include small interfering RNAs (siRNAs), long non-coding RNAs (lncRNAs), and microRNAs (miRNAs) that might affect gene expression by blocking translation or aiming to degrade messenger RNAs (mRNAs).

Royal Jelly
Honeybee phenotype is influenced by the epigenome, which is influenced by their early nutrition. With identical genomes, two distinct female castes are produced: a long-lived queen with fully developed ovaries and a short-lived, functionally sterile worker. A queen-destined female larva is given enormous quantities of royal jelly. Queen structure, including the fully developed ovaries required to lay eggs, develops as a result of the royal jelly. The hypopharyngeal and mandibular glands of nurse honeybees create royal jelly.

Horn Length of the Male Dung Beetle
The horn length of male dung beetle (Onthophagus acuminatus) is determined by how it eats while in the larval stage. Male larvae that eat past a certain threshold are able to grow horns that are longer than their body. However, if the males do not meet this threshold or have less access to food; they will grow little to no horns. The amount of food available to the larvae is what determines the amount of juvenile hormone in the beetle. Juvenile hormone directly correlates to horn growth. The size of the larvae at the last metamorphosis determines how large the horns can become. Beetles with differing horn length exhibit different mating behaviors.

Obesity
Obesity, including being overweight, is a common disease that affects more than 35% of the world's population. You see obesity and overweight individuals all over America. These diseases can form during utero, in later life based on genes from your parents, and nutrition intake throughout life. Maternal obesity can affect the fetus by causing increased risk of obesity, heart diseases, diabetes, asthma, and CNS malformations (Congenital Central Nervous System). Obese mothers commonly have children that have CNS malformations including Spina Bifida, Anencephaly, and Isolated hydrocephaly.

Type 2 Diabetes
Type 2 Diabetes is a condition where the body has problems regulating sugars and using them as fuel. The two main problems that people with this condition have are the pancreas not creating enough insulin for the body and their cells not responding to insulin. Diet can influence the risk of getting diabetes. Specifically, the more an individual consumes unhealthy beverages, like sodas, vitamin waters, sweetened tea, the higher the chance of developing type 2 diabetes. Managing the disease by implementing nutritional recommendations can help improve glucose in the blood. Type 2 diabetes studies show that consuming certain fruits, like those in the citrus category, can help to reduce the risk of developing the disease. Having more natural foods in the diets will also lessen the chances of developing this condition.

Human Lactation in Nutritional Epigenetics
Lactation is one of the primary ways for mammals to optimize growth of their offspring. Through this process the infants are receiving essential nutrients required for healthy development. These inadequacies of micronutrients noted in the female’s diet can directly translate to congenital defects in their offspring. Due to the early exposure of malnutrition in prenatal and postnatal fetal development, epigenetic changes in gene expression may occur in the form of DNA methylation, histone modification, and the interaction of ribonucleic acids for activation or silencing of genes.

Although the exact mechanism of neural pathway of the infant’s development from maternal milk supplementation is unknown, conclusions have been reached that suggest the potential epigenetic effects of bioactive components such as growth factors, non-coding RNAs, stem cells, and early development of the fetal gut microbiome to be a major part of this process.

Exosomes derived from human mammary glands possess the ability to cross the blood-brain barrier due to their extravesicular nature. This provides protection for the enclosed micro-ribonucleic acids (mRNAs) and long-non-coding ribonucleic acids (lncRNAs) that helps brain development and function by upregulation of associated genes. As the exosomes are extremely stable vesicles, they have the capacity of preservation from digestive enzymes and are available for reuptake into the bloodstream via intestinal epithelial cells. However These essential RNAs have been noted to be deficient in pregnant females with conditions such as diabetes with translation to obesity and even psychological factors.

Stem cells from breast milk containing nestin, a neuroepithelial stem cell protein, have the ability to differentiate into neural cells or can perform as epigenetic regulators in the brain. A study by Hosseini et al. proved the human breast milk can have neural implications by their carried stem cells which can further progress into highly differentiated neural cells including oligodendrocytes and astrocytes. This association has proposed new pathways for explanation of the short- and long-term effects of human breast milk in fetal development.

As for the microbiota located within breast milk, the different bacteria can help steer the infant’s development of their own gut microbiome. Which is a known precursor for establishment of beneficial epigenetic modifications and neurodevelopment as shown in a study performed by Pannaraj et al. that maternal breast milk performs contributions to the gut microbiome by promoting colonization of beneficial bacteria. Methods of exposure for allotment of the colonization of beneficial bacteria postnatally include the maternal flora, delivery of milk expression (breast pump or skin-to-skin), and the infant’s diet. This accumulation of microbiota can directly influence specific epigenetic patterns by the Gut-Brain Axis through interactions between the central nervous system and gastrointestinal tract.