When you think of occasions like Thanksgiving, Sunday brunch, or a summer BBQ, you probably expect certain foods. The menu will include specific items to match the occasion. The amount of food will also vary depending on the number of people.

Just like these special occasions, your body also follows a specific “menu” for conditions like embryo development, intense exercise, healing from an injury, or growing taller. How does it know what and how much to make? For each condition that our bodies experience, there is a specific menu to respond to that situation known as gene expression.

Every cell in living organisms contains instructions for every structure (protein) and process in your body. These instructions are contained in a material called DNA. DNA is the “cookbook” for your entire body. It has a specific “recipe” (gene) for each protein. The number of “servings” of each protein is determined by the amount of mRNA made in each cell. (for more details on how proteins come from DNA, click here).

DNA = cookbook
gene expression = menu
gene = recipe
mRNA = number of servings

When the right recipes and menu are used, the dinner is a success.

For example, at a traditional Thanksgiving dinner for ten people, you’d expect a large turkey, gravy, stuffing, and mashed potatoes with an appropriate amount of servings for each person.


What Can Go Wrong?


During an organism’s development from an embryo to an adult, the correct combination of genes must be expressed at the right time to allow the embryo to develop properly. If a developmental toxicant is present during embryo development, the wrong combination or amount of essential genes are expressed. The mis-expression of genes can then lead to the deformed fish just like the ones what you observed in Dr. Tanguay’s first experiment.

When there are mistakes with the recipes and menu, the dinner is a failure.


Going back to our Thanksgiving dinner example, this could result in an overcooked turkey, not enough gravy, no mashed potatoes, and watermelon instead of stuffing. This is not what you expect at a Thanksgiving dinner!

How do you measure changes in gene expression?