So, for the past few weeks I’ve been busy testing out some DNA extraction kits to see which works best for the dung samples I’m working on. The basic process is the same across the kits and the kits just simplify the steps by making nifty chemicals and solutions to help you out! Swipe through the photos and the explanations are numbered below.
1. First up you need your starting material, be it dung, saliva, blood or hair etc etc. With dung samples you have to carefully and sterilely scrape the outer edge of the dung pellet, because that’s where the animal’s own DNA would be found.
2. Once you have a decent sample you add a type of lysis buffer, which is really just a chemical that helps break the cells open so the DNA can come out. Sometimes it helps to heat the sample up, so you incubate it for a few hours to overnight.
3. After this you can add more chemicals to help clean up the sample liquid, because there might be things in there that negatively impact the DNA. You can also spin the tubes in a centrifuge, this is a machine that spins at crazy high speeds, so it separates the DNA from the rest of the cell material. Most kits also include a spin column which filters the DNA out of the liquid so you can test it without all the other stuff getting in the way.
4. Once you think you have the DNA; you test this by performing a gel electrophoresis. This is a way to separate different DNA pieces based on the DNAs length. So, you have to prepare a gel, which acts a sieve when the DNA moves through with the bigger pieces taking longer to move through.
5. You add your DNA, along with a special dye that binds to it, to little holes on the one end of the gel. You then add an electrical current to the liquid surrounding the gel and this moves the DNA through the gel.
6. On the photo I’ve circled the DNA so you can see the extraction worked, thankfully!
You have DNA, so what? Well next up is the process of making more DNA and sequencing it so you know what animal the DNA belongs to!
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