By Benjamin Simpson, Shenfield High School, Essex, UK
When I arrived at the lab, the first thing I noticed was how casual everything was. Even the principal investigator arrived at about 11am. I expected to find a strict regime of when to arrive, what to do and what to wear. Anna and Nikki were my supervisors in the Attwell lab at University College London. My project involved using zebrafish to investigate the development of myelin (a substance which is wrapped around neurons to increase conductivity). Zebrafish are especially useful because they are transparent allowing us to view the development under a microscope without harming the fish or embryo. On the first day of my placement they were only a few hours post fertilisation and so were still just a bundle of cells on a yolk. I learnt how to maintain the embryos through filtering out the dead ones and changing the water.
Zebrafish embryos 2 days post fertilization
I also gained an insight into where the fish were kept. The scale on which they were kept was astounding. There were over 1500 fish in the facility. It was not dissimilar to a library but with tanks of fish instead of books. I was taught to tell the difference between the male and female fish. The females are a slightly different colour and slightly fatter with a tube to deliver eggs. We put the fish into pairs of a male and a female of the correct genetics so that they would lay eggs.
Zebrafish embryos 30 days post fertilization
Further on into my placement, the fish had changed considerably and were developing organs. I was shown how to dechorionate them. Chorion is the bubble they grow in up to this point. Dechorionating (or hatching them) is completed under a microscope with two sets of tweezers. I used them to pull the chorion apart and allow the fish out. This is beneficial for the fish and us as we can see them more clearly and the fish is free to move. Some of the fish had genes to be fluorescent in certain wavelengths of light, but they had not really developed enough to see much. There was a green haze around the heart and a red haze around the otoliths. Otoliths are the two dots in the ball behind the eyes. They are used for navigation and telling which way round the fish is. The blood flow was also visible. Eighty percent of the oxygen required by the fish can be gained through the skin as at this stage as the surface area to volume ratio of the fish is very high.
In order to observe the fish in detail, we had to anaesthetise them and mount them on slides. It was a surprisingly difficult task. To line up and orientate the fish (in the small amount of time before it set) we had to use a pipette tip and microscope. Bearing in mind that even then the fish were only 2-4 mm (my estimate). I managed to do six on a slide. My supervisor Anna, however, was doing twelve at a time with even greater accuracy. The fluorescent fish had also grown and become a lot clearer. The heart was now incredibly clear. I could easily see the chambers and valves. The red was showing myelinated areas which were now the otoliths, jaw, fins, and lateral line (grows above spine).
When the fish were large enough for the planned investigation, we mounted and screened them. This consisted of viewing each fish beneath the microscope (confocal) and seeing which ones had the best developed nervous systems and would work best. Two electrodes were inserted onto the spine of the fish, one near the head and one down on the tail, then a needle into the brain of the fish. The first electrode was to send a signal down the spine and the second to record it. (Stimulating and recording electrodes). We took the heart rate of the fish before and after injecting the fish with tetrodotoxin (TTX), a poison produced by puffer fish. We were looking for the impulse sent by the stimulating electrode to no longer be received by the recording electrode one the TTX was introduced. This is due to the TTX closing the potassium channels in the neurons and preventing the impulse from being transmitted. It worked fantastically.
While working at UCL, I was invited to a gathering out on the main quad to celebrate the publication of a paper in the journal Nature by some of the researchers in the lab. It was a nice opportunity to get to know everyone at the lab better.
I am very grateful to Niki, Anna and Dave Atwell (the principal investigator) for hosting me and for being so friendly and welcoming.
This experience was an interesting insight into what life as a professional researcher is like. I found that one of the disadvantages of the relaxed work style is that people can turn up in the afternoon and work can easily go on until midnight. Some of the days, even for me as a placement student, were quite long. The work also seems to be heavily driven by the need to finish a paper or acquire a grant. The phrase “publish or perish” was extremely relevant. Job security also seemed to be an issue.
On the upside, you can take lunch whenever suits you and there’s far more freedom than I think you might find in other jobs. I also found that the self-motivation needed for the work suited me well.
The Biochemical Society is proud to support in2scienceUK. In addition to sponsoring five students each year, the Society also gives delegates attending our events the opportunity to donate to the scheme. In 2016 this allowed us to provide an additional £600 in funding.