Day three starts with us in breakfast consoling ourselves about not winning in the quiz last night.
Then - after the walk to the QMC, we're back in the lab, this time looking at cells from manduca sexta.
They eat a diet rich in potassium, so they get a lot of K+ in their diet, which they have to manage. A lot of this enters their system, and they have to get it out again before it messes up their internals.
We hypothesised that there was some sort of active transport going on here, to pump the ions back out.
We started our day by looking at the pH values of the various stages of the gut, food and faeces of the worm, and also its internal hemolymph system. This is because one hypothesis is that there is a H+/K+ antiporter. If this is the case then the pH should change as protons are pumped in exchange for K+ ions.
We then went on to measure electrical potential across the gut wall using a small piece of tissue held in a clamp between two solutions. We altered the potassium concentration to try and see what rate it could pump the ions, and we also used an electron transport chain blocking substance dinitrophenol to disable ATP synthesis and to see if that stopped the pumping and so gave evidence for an energy hungry transport reaction.
Another group look at sections of tissue under the microscope and also electron-micrographs to look for clues in the histology of the cells.
After lunch we had to prepare a five minute presentation with slides about some aspect of the work we had done over the past two days. Sue and I did a presentation on oxygen uptake differences between skin and muscle cells based on the data we found yesterday.
Others did similar sorts of things, or ones based around the manduca investigation. There was a lot of good stuff there, but with the best will in the world, by the time you'd heard the 10th presentation on oxygen uptake in muscle v. liver, it began to pale a little.
Once that was done and we'd listened to all the talks, we went back for tea, just beating the rain.
After tea, a briefing on the next days activity, photosynthesis. We also had a partner shuffle.
This was followed by a poster session where we had 20 minutes to make a poster based on a rather sketchy experimental report. We did it in 10! That probably wasn't the point though!
A night in the bar listening (and avoiding) to the karaoke, but chatting with our next lab partners and some friends.
A pretty early night really.