Science Buddies: "Ask an Expert"

We are working with Pyrocystis lunula dinoflagellates to study the bioluminescence under warmer and cold conditions. I did loosen the caps of the tubes when I first received them but when I adapted them to their photo period (12 hour dark/12 hour light) they were inverted so I had to tighten them again. I did check for bioluminescence - they glowed. I then kept them in that 12 hour dark/12 light period for 2 more days, careful to keep them at about 23-24 degrees C. Now I've tried putting 2 tubes in a warmer area, 2 in a colder area, 2 kept in the same temp. None are glowing.
Does anyone have any ideas? Gas build up from not keeping the caps loosened? The UTEX website says they should last for weeks and that they can be temporarily placed at higher or lower temps. Suggestions?

Hi JoEllen,

I am assuming that you tried agitating the cultures to get them to glow. It could very well be that a lack of gas exchange killed your dinoflagellates. They are algae, which do produce oxygen but also use it for cellular respiration. They need gas exchange to stay alive.

Here is an online guide to caring for Pyrocystis: https://empco.org/empco/images/quickguides.pdf. Yours probably came with instructions, but it can't hurt to look through these quick tips.

If you did accidentally kill your dinoflagellates, you may have to get a new set. It looks like the UTEX kit costs about $60, and I found a place that provides cultures for as low as $25: http://empco.org/edu/index.php/biolumin ... unula.html

I hope this helps! You have a great project, and it would be great to see you be able to complete it.

Heather

Hi Heather,

Yes, I did agitate them but they are still not glowing. One thing I did not do is test each of the vials when I first got them. If I re-order I will be sure to do that. Also, I probably should look at them under the microscope to make sure the cultures are alive as well.

Thanks so much for your response! Also, thanks for the references. Any help is always appreciated!
I really hope I can make this project work. I was really excited about it and the ties it could have to global warming - the impact on sea life and how the melting of polar ice will affect the ocean temps, etc.

Thanks again!

JoEllen

Hi JoEllen,

I'm glad to be of help! I hope you are able to continue with the project, especially given your interest in its broader relevance.

If you continue to struggle with the Pyrocystis cultures, you could also do a similar project with Daphnia (the water flea). You could find several sources for purchasing Daphnia cultures; here is one online source: http://buylivefishfood.com/buy_live_dap ... tures.html. Here is a site with information about caring for Daphnia: http://web.cecs.pdx.edu/~davidr/discus/ ... phnia.html

One cool thing about Daphnia is that you can look at their heart rate under the microscope. You could see how different temperatures affect their heart rate, and you can also see how different chemicals affect their heart rate.

I hope you are able to pursue what interests you. Please keep me posted on your progress!

Heather