Recently I tried out a new dye on the cercariae that I’m studying. Cercariae are the free-swimming stage of trematode parasites that search for the next host in their life cycle. For my research, I’m studying the trematode Euhaplorchis californiensis (EUHA), and their cercariae are on the look-out for California killifish (Fundulus parvipinnis). I would like to be able to infect wild-caught fish in the lab, and be able to differentiate between the parasites that the fish became infected with while they were living in the wild from those parasites that they acquire when I infect them in the lab. To differentiate between lab and field infections I was hoping to mark cercariae from lab infections with a fatty-acid analogue dye called BODIPY FL C12. This dye binds to lipids in cell membranes, and it “glows” when the dye is excited by photons. Here is what EUHA looks like after it has been stained with the dye:
Look at its little eyespots. What a cutie.
The parasites were very active, which suggests that the dye wasn’t harming them in any way. Unfortunately, the dye wears off very quickly in the presence of light. I was quite surprised at how quickly the dye stopped fluorescing, and after 5 minutes in a completely dark room (except for the light from the microscope) it was nearly impossible to see the cercariae. This is a big problem for me, because California killifish have somewhat transparent skulls, so I imagine that the dye would wear off pretty quickly. Soooo, I probably won’t get a chance to use this technique for my experiment, but it sure was fun making my darling little brain parasites glow!