Guest post by Emma Langan
I’m on the RRS Discovery in the Southern Ocean, doing DNA sequencing of Antarctic algae or phytoplankton. To do this I’m using a tiny portable DNA sequencing machine called a MinION (shown next to the other kind of minion in the top photo).
Phytoplankton are microscopic algae which live in the oceans and make their energy from the sun, just like plants on land. They are important for making oxygen and also carbon from the atmosphere – excellent news as too much carbon in the atmosphere is one of the causes of climate change. They are also the bottom of the food web, so without them, there wouldn’t be penguins and whales and seals. My research is focused on investigating which species of phytoplankton are present and what tricks they use to survive somewhere as cold as Antarctica. To investigate this, I use DNA sequencing.
DNA is the basis of all life on earth. Like the code in a computer program telling a computer how to work, DNA tells your body how to work. DNA is made up of 4 bases, called A, T, G, and C which appear in different combinations making genes. Genes tell the body which proteins to produce, and proteins make muscle, or hair, or eyes in the right places. Different genes are what makes plants different to animals, penguins different to elephants, and you different to me. Looking at an organism’s DNA gives us a lot of information; we can use it to see which species are present in a sample and also to see what special genes they have which allow them to live in ice and snow, and in the dark.
The CTD is used to collect water samples from different depths
To look at Antarctic phytoplankton DNA, first we take water samples from the ocean and filter it to catch the phytoplankton. Next, I remove the DNA from all of the proteins and other sticky stuff in the cells. This process is called DNA extraction (if you’re interested and have an adult to help you, you can quite easily extract DNA from fruit or vegetables using things you can buy from a supermarket https://www.sciencefocus.com/science/how-to-extract-dna-in-your-kitchen/.)
Once I have extracted the DNA, I put it into the MinION which runs for 2 days, and you can start to see which species are present almost straight away. The MinION makes a list of all the bases that are in the DNA and compares it to DNA from species that we’ve already sequenced. This way that we can tell which species are in a sample, and what genes they have.
It’s really exciting to be able to do DNA sequencing on a ship, because usually we have to send samples home which takes months, and we don’t know if anything has changed since we collected them. Most DNA sequencing machines are the size of an oven so you can’t take them with you. The MinION is so small that we can take it anywhere – someone even did DNA sequencing in space. I’m going to use the information I get from it to look at whether the phytoplankton species change as the oceans get warmer due to climate change, and to investigate what genes they have which let them live in the Antarctic in the first place.
Emma Langan is a PhD student at UEA and Earlham Institute. You can find out more about her work by following her on Twitter @EmmaGLangan