Saliva. It’s not very glamorous, and it doesn’t seem all that scientific, but the fact is that we can get a lot of information from just a small swab of spit. And that’s exactly what we do when we process your saliva sample from one of our Genetic Direction kits. But how do we take a q-tip soaked in spittle and extract DNA from it?
In the not so distant past, most DNA samples used for lab work were extracted strictly from blood. While blood can provide a higher quantity and quality of DNA, it’s not exactly ideal for personalized test kits. To start, using blood samples can be time consuming, requiring an appointment with a trained phlebotomist to actually take the sample. And then there’s the whole bit about the needle…not exactly anyones favorite experience. Transporting blood samples can also be tricky, posing as a potential biohazard if any spillage or contamination were to occur. But in 2011, the DNA game changed when the FDA approved the first saliva collection device to be used for DNA extraction. Since then saliva samples have been the go to, non-invasive standard for at home DNA-based test kits.
When one of our programs arrives at your door, it comes equipped with a little swab kit for DNA collection. The process of collecting your sample is as easy as rubbing the q-tip along the inside of your cheek. The q-tip is then placed into a solution that stabilizes your saliva and prepares it for its journey off to our labs. But once your spit takes flight via the mail and lands in our hands, how does turn into a true DNA sample?
Step 1). Breaking open your spit cells.
Your spit is filled with DNA, but that DNA is all found within cell walls, so the first step in getting to your DNA is breaking down your cells. There are several ways this can be achieved, but the most common way is to actually use soap! Soaps are excellent at breaking down fats and when mixed with your saliva, soap actually acts to break open the membranes of your cells which are made up of lipids (also known as fats).
Step 2). Spin it down.
Once the cells have been split open and the DNA has spilled out, the sample is put into a centrifuge. That’s right, we spin your saliva sample until the DNA separates out into its own layer. This happens due to a difference in DNA density compared to all the other “stuff” inside your cells.
Step 3). Precipitation.
We’re not talking about rain. Precipitation is also the process of extracting a substance from a solution. In this case, it’s the final extraction of your DNA from the rest of your saliva sample. This step is done using a chemical, usually ethanol, that makes DNA clump together so that it’s easier to separate out from everything else.
Voila! That’s how we get your DNA from your saliva. Now we know what you’re thinking, no way does DNA extraction involve three simple steps. Well, it really is that easy. In fact, you can perform DNA extraction at home using strawberries. You heard correctly, strawberries.
Everything has DNA, it just so happens that strawberries have abnormally large strands of DNA and lots of it, meaning that you can perform DNA extraction that is actually visible without hundreds of thousands of dollars worth of fancy lab equipment. Here’s what you need.
- Three strawberries
- Chilled rubbing alcohol
- Salt
- Water
- Soap (standard dish-washing liquid will do the trick!)
- Cheesecloth or paper filter
- Funnel
- Small bowl
- Glass
- Resealable plastic bag
- Bamboo/wood skewer
- Measuring cup and spoons
And here’s what you do.
1). Place the strawberries into the resealable plastic bag, push out all of the air and seal.
2). Squeeze and smash the strawberries through the sealed bag for two minutes.
3). Mix half a tablespoon of salt, a third cup of water and one tablespoon of soap in a small bowl.
4). Add three tablespoons of this extraction mixture into the bag of strawberries. Push out all of the extra air and seal again.
5). Squeeze the strawberry mixture through the bag for one minute.
6). Place a cheesecloth or coffee filter into a funnel and pour the strawberry mixture into the funnel. Let it drip through the cheesecloth/filter and into a tall glass until there is very little liquid left in the funnel.
7). Measure out half a cup of cold rubbing alcohol and tilt the glass containing the strawberry mixture to slowly pour in the rubbing alcohol down the side of the glass. Keep pouring the alcohol until it has formed about a one inch deep layer above the strawberry liquid. Do not let the alcohol and the strawberry liquid to mix.
8). Dip the bamboo/wood skewer into the jar where the two layers of liquid meet and then slowly pull up the skewer. It should be covered in a sticky substance. That’s strawberry DNA!
And that’s that. Extracting DNA is really that simple and we can guarantee that after you try it at home, you’ll never look at a strawberry the same way again.
