Amplifying the DNA

Once the separation of the samples and the extraction of their DNA are finished, it is time to amplify them, using the polymerase chain reaction (PCR). With this aim, we use a pair of primers capable of amplifying the chosen DNA fragment (in our case, a fragment of ribosomal RNA 18S, which is present in all eukaryotic organisms).

With this process, we obtain a mix of amplified DNA fragments, between 150 and 200 base pair long, representative of all the organisms present in each sample. Every fragment is also labeled with a "molecular barcode" which allows to identify the sample where it comes from. After checking the success of the amplification process on an agarose gel, we will send the samples to the ultrasequencing unit, where we will be able to read the sequences of the amplified DNA fragments.

Image of the agarose gel obtained with the DNA of the samples from Islas Cíes and Cabrera