It’s not all set in stone: The genes you inherit are not the end of the story
By: Yaamini Venkataraman
Flashback to your high school biology class. Your teacher was droning on about the upcoming exam about “the central dogma”. You passed the test, but don’t remember the concept. Let’s refresh your memory.
Every living thing on the planet operates from an instruction manual: DNA. Organisms don’t draft these manuals themselves, but inherit them from their parents. Within each manual are directions for breathing, obtaining nutrients, and reproducing. Need to digest that slice of pizza you just ate? Your body unravels the DNA until it reaches the right section. These instructions are then transcribed into mRNA, and finally translated into proteins. Proteins, like lactase, digest that cheesy slice.
The progression from DNA to mRNA and protein is the central dogma. It’s the crux of everything we know is true. Even Sir Charles Darwin understood the overall concept of inheritance — the unique combination of your parents’ genes leads to predetermined responses to your surroundings.
So why is it up for debate?
Central dogma 2.0
Although they still believe and support the central dogma, researchers like me are beginning to question whether there is more to it. The dogma is no longer a one-way street from DNA to proteins — it’s a complex, convoluted web with alleyways and four-way intersections.
These alternate routes form the study of epigenetics. The essence of the DNA you inherited from your parents is not changing. But epigenetics alter which parts of your DNA are accessed, when they are accessed, and how frequently they are used. Take identical twins, for example. Because identical twins are born from the same fertilized egg, they have perfectly identical DNA sequences. But if one develops arthritis and the other does not, it’s likely that the environment of the arthritic twin influenced how their gene expression.
Testing what we don’t know
How much of us hardwired, and how much of it can be shaped by our environments? It’s difficult to answer these questions just by studying people since we tend to live long lives. This is where model organisms like the Eastern oyster come in. Not only are oysters tasty treats, but they are ecologically, socially, and economically important for several coastal communities. However, they are in peril due to acidifying oceans caused by ongoing climate change. Their shells dissolve, baby oysters are deformed, and they are unable to put their limited energy towards growth and reproduction efficiently.
A group of researchers at the University of Washington and Northeastern University believe oysters are capable of epigenetic regulation. Our partners at Northeastern University, Dr. Kathleen Lotterhos’ lab, exposed one group of oysters to acidic conditions, and another to normal seawater. My job is to peer inside the oyster’s genome and see if exposure to acidified water would change the way oyster DNA is expressed in such a way that it helps oysters resist these conditions.
Oysters react to unfavorable environments by producing proteins — that response is coded in their DNA. With epigenetics at play, maybe that response is not all set in stone. The acidified conditions that the oysters live in could alter how and when important response genes are expressed and which proteins are produced.
Let’s return to the central dogma. We know that DNA turns into mRNA then proteins, and epigenetic regulation can change the frequency of certain sections of DNA being expressed. The environment is just one thing that can modify the epigenetic makeup of an animal, and scientists like me are just beginning to dive into the extremely messy molecular street plan of back alleys, intersections, highways, and more. Is nothing truly set in stone anymore? Maybe not. But having some space from “genetic destiny” is certainly liberating.