Blood. It tells a story. I'm not talking crime scene kind of story here. I'm talking living, active, current, a dialogue if you will. When you are sick or even if you feel healthy and go in for a physical the doctor takes your blood and then checks off a bunch of boxes of what to check or look for. If the number of white blood cells are elevated that may signal an infection - they can even tell if it's bacterial or viral depending on certain characteristics. Markers for cancer, how well your cells are processing oxygen - there is a plethora (nniiiiiiice word) of things that can be learned from examining the blood. WHY? I'll give you a few minutes to think it through and come up with your own hypothesis.
The blood samples we take from each fish serves many purposes. Some of the blood is transferred into a centrifuge tube using a pipette as seen here.
Those of you in my class should know this. Did I hear someone say capillaries? Awesome - you are on the right track. Capillaries, which are the smallest of blood vessels wind through your entire body and if they are not actually touching one of the trillions of cells in your body they are at most one is around 20 microns away (that's scientific terminology for a teeny tiny itty bitty really, really small way away). Your blood is exposed to every cell in your body which also means that everything that comes in or goes out of your cells is carried in your blood. That is why we are so interested in fish blood during these experiments. The surgeries that we are performing on the fish to put insert a cannula, a long tube inserted into its dorsal aorta, allows us to take blood samples throughout the experiment. This gives us a window into what is going on inside the fish in a physiological sense. I've mentioned this before but now I can show you some results. If you look at my journal from April 29 I showed the apparatus we have to measure the amount of oxygen in the blood. But we are using a device that is used on humans. We were able to use a machine called an iSTAT that takes specific blood information. In our case, we are going to look for the production of lactaid.
This is the iSTAT device. The blood is placed in the cartridge as seen here.
That will indicate a lack of oxygen being processed in the cell. We are taking blood samples at the start of the experiment, in the middle, and then when the fish is loosing its ability to stay upright. As we continue I will keep you posted on what we are finding. The tissue samples will be analyzed more closely in the lab, but this device can give us an immediate window into what is going on.
The cartridge is inserted into the iSTAT, which reads the blood and prints it out digitally on the screen.
Within just a couple minutes we get a readout. Some of the information isn't so helpful for us as this is calibrated for humans (note the 37 degrees C). But we can get some interesting information. pH, how much oxygen and carbon dioxide there is. Right now the lactaid is in such small amounts it can't be measured. How do you think this might change at the end of the experiment? Hint: Under what conditions do you see lactic acid being produced?
I'll leave you with some questions to ponder. What will this tell us if we see more carbon dioxide in the blood? If the pH gets lower? And how are the two related? Hey, this is like a quiz from the last unit...