After a preliminary successful extraction of DNA from kiwi with a standard protocol (here or here), we decided to try if we could do the same with our own DNA. The general principle is similar to extracting DNA from fruits except that we start with far less material.
The first step was to obtain some cells from our body! The easiest and quickest way is to retrieve cells present in our mouth. For this, we first prepare a mixture of water and salt (2 spoons of salt in 100 ml of tap water) and gargle it for 30-45 seconds.
The liquid now contains human cells and other stuff such as bacteria. The next step is to break the cells to release our genomic DNA in the solution. To do this, we just added a spoon of kitchen detergent to the solution and mix it.
To improve the visualisation of DNA, we also add some soy sauce to the solution to make it darker. However, since we retrieve at the end more DNA than expected, this step can be removed since it doesn’t help the final purification steps.
The penultimate step is to precipitate DNA by adding pure isopropanol to the solution and mix it. It generally takes a few minutes before the DNA start to became visible. We transferred some of our DNA to a clean tube with pipettes to keep it frozen until we test it by PCR with primers again a specific human gene to verify that we really have genomic human DNA (more about this next time).
DNA is visible in the tip DNA pellet with soy sauce
Just to compare to the amount of DNA retrieved from the kiwi extraction (all the white stuff in the bottle) and a photo of the material used for extraction: