PCR for Peanut Chloroplast DNA

This article from Science Daily summarizes a recently published article in the Journal of Agricultural and Food Chemistry about a new method involving DNA to detect trace amounts of peanuts in baked goods, chocolate and tomato sauce. This is extremely practical in the sense that peanut allergies are one of the most common allergies, and there are at least 3 million people in the US alone that suffer from this type of food allergy (1). A lot of people with this type of allergy can suffer from anaphylaxis when the allergy is triggered, even from only trace amounts of peanut. Anaphylaxis can be life-threatening and usually involves breathing difficulty, rashes, and nausea;  if not treated with the Epipen, it can lead to unconsciousness or death in extreme cases.

The team chose to study the chloroplast DNA of the peanut for several reasons. First, there had been previous research involving testing for the proteins in the peanut. This research is effective, but many of the proteins in peanuts can be destroyed during food processing. The nuclear DNA in the peanut can also be tested for with PCR, or polymerase chain reaction. However, it may prove challenging to find nuclear DNA sequences unique to only the peanut. The team wanted to try a new approach with chloroplast DNA in peanuts because chloroplasts are more abundant in the peanut compared with having only one nucleus per cell. The peanut chloroplast DNA is unique to the peanut only, so the team did not have to worry about overlapping sequences with other foods.

The team was able to successfully use PCR to test for three sequences in the peanut chloroplast DNA. Having three regions to test made their results even more convincing that the DNA is from peanuts, and not any other plant. The PCR successfully detected trace amounts of peanut in all of the food they tested, and were able to test for the peanut traces as low as 1 PPM. This is an improvement upon the 10-50PPM limit in PCR that tests for peanut nuclear DNA.

The reason I chose this article and enjoyed it was because of my personal connection. I have a severe egg allergy, and it too can be set off by trace amounts of egg, and it can even be triggered by breathing in the air containing eggs. I understand how serious these allergies can be because there can be cross-contamination with pots and pans and that is enough to trigger an allergic reaction. I am very happy to know that PCR can now detect trace amounts of peanut chloroplast DNA, but eggs do not have chloroplast. Maybe another team can develop a PCR method that detects mitochondrial DNA unique to eggs. It makes me very happy to know that there is research out there that is helping food allergy suffers make their lives a little easier. Maybe one day they will invent some kind of food scanner that can tell an allergy sufferer if the food contains the allergen. We're not there yet, but maybe one day.


Related article:

Scientists Have Identified A Key Gene Linked To Peanut Allergies

Childhood Food Allergies Caused by a Combination of Genetic and Environmental Factors

Researches have found a link to child food allergies and genetic factors along with environmental factors. A specific combination of environmental factors and genetic factors can trigger infant and childhood food allergies. In order to trigger these allergies a child would have to have genetics that change the skin absorbency, have been exposed to infant wipes that leave soap on the skin, and have been exposed to allergens such as dust or food allergens. Joan Cook-Mills is a professor of allergy-immunology at Northwestern University Feinberg School of Medicine and was the lead researcher on this study. She explained ways to prevent these environmental factors, which when combine with the genetic factors can cause childhood allergies. She said to, “Reduce baby’s skin exposure to the food allergens by washing your hands before handling the baby. Limit use of infant wipes that leave soap on the skin. Rinse soap off with water like we used to do years ago.” The soap in the wipes disrupts the skin barrier. This link between environmental and genetic factors that causes food allergies was discovered through clinical evidence of food allergies in humans and tests were done using neonatal mice models. The clinical evidence showed 35% of the children that were looked at who were looked at with food allergies, also had dermatitis. Dermatitis is caused by three different gene mutations that reduce the skin barrier. This study is helping to understand food allergies and how they develop which is important to know for developing more responsive medicine. Cook-Mills’ goal is to discover interventions that will more effectively respond to signals and block the development of food allergies.

Food Allergy is Linked to Skin Exposure and Genetics

This article focuses on the physical and genetic factors that have been discovered to have a large role in causing food allergies in infants and children. The physical factors include: The use of baby wipes that leave behind large amounts of soap-residue, exposure to allergens that are found in dust, and exposure to food particles coming from caregivers. The genetic side lies in genes that may alter skin absorbency. When these physical factors occur in the presence of a child that also expresses the skin absorbency-altering gene, a "perfect storm" is created that can trigger food allergies. Animal studies were carried out using mice to confirm this very interesting discovery.

In today's world it seems as though more and more children (and adults) are discovered to have food allergies and in many cases these allergies are very dangerous and have altered school policy. I think this research seems valid and very vital because of these factors. As someone who is studying to be a teacher and has worked as a substitute teacher, children's allergies have become something handled with strong caution, and anything we can do to prevent those allergies is huge as we push into the future.

Link: https://news.northwestern.edu/index.php/stories/2018/april/food-allergy-is-linked-to-skin-exposure-and-genetics/

Additional link: https://www.sciencealert.com/dust-food-and-baby-wipes-linked-to-infant-allergies