Science Buddies: "Ask an Expert"

Good Afternoon

I am a 9th grade student trying to put together an experiment with bioluminescent dinoflagellates. I have been researching this topic and have learned that vitamin B is believed to be very important to the health of plankton. I would like to do an experiment with bioluminescent dinoflagellates and B12. I am a little stuck. Here are my questions:

How much vitamin B would be reasonable to add to a vial or bottle of these organisms? What would be a good amount to start with?
Can I just use liquid B12 from the drugstore?

I am assuming the vitamin B will increase the glow of the organisms and therefore the ones with the brighter glow will have better fitness than those organisms with little or no B12 additive. I just do not want to kill them with too much B12. Any suggestions and pointers you have would be helpful.

Thank you,
Sam

Very cool idea! It is good you are spending the time to design your experiment. It is ambitous, but you can definately do it. Here are some key questions, and suggested answers.

How will you quantitatively measure your results?
You need a method to tell which organisms are glowing brighter. In a lab we would use a luminometer, which collects all of the light over a given period of time and measures it. What you could do is use a camera mounted on a tripod. Turn off the flash, set the shutter speed as slow as possible. Many digital cameras let you do this on manual mode. Then in a dark room you could take long exposure photographs (maybe 10 seconds each) of each of your viles. That way you can directly compare how bright they are. You can be creative in figuring out how to optimize this.

How will you induce the cells to glow?
I don't know much about those organisms, but I do not think they glow continuously. Many react to pressure (such as slapping the water or shaking a bottle). You could figure out a repeatable way of exciting them all at once. That way you can test how each set of cells in different concentrations of B12 react.

What conditions will you grow the cells in?
As you asked, what is a reasonable B12 concentration to test. Well I will answer by telling you, that is your job to find out. First find out what else the cells need to survive. How do other people grow them in a vile? Then put equal amounts into several viles where everything is the same except B12 concentration. Your control will have none, and I would test the entire range of the effect. Put one group into 100 millimolar B12 (note that it is sold by mg in the store, so you can use that to create your solution), then another in 1 millimolar, another in 100 nanomolar, and another in 1 nanomolar B12. Your teacher can explain how to calculate the molar concentration of something. It sounds bad, but it isn't hard.

Best of luck, you can do this.