Toxicology: Better Living Through Death
My lab works with two species of fish- Zebrafish (Danio Rerio) and Killifish (Fundulus Heteroclitus). Given the short time frame for my research project, I was originally advised to use Zebrafish- which reproduce like crazy and develop much faster- for my experiments. However, due to a tragic accident that killed the majority of the Zebrafish population, I'm using Killifish instead. In case any of you fish enthusiasts were wondering, we did get new fish in, and they seem to be doing pretty well and are breeding surprisingly regularly. But there is a chance that because the fish aren't used to this lab environment yet, co-stressors linked to an unfamiliar habitat (eg. different ammonia levels in the water) may skew experimental data. By the time we can be confident that they're used to the lab and everything, it will be too late to use them for my project. I don't mind though, because Killifish are much hardier, which means that it's much harder to kill them on accident (win!).
My project, thus far, is to look at differences in how Killifish from two populations deal with environmental pollutants. The first site is King's Creek, a relatively clean body of water. The second is a superfund (extremely polluted) site called the Elizabeth River, which is contaminated with polycyclic aromatic hydrocarbons (PAHs) from creosote, a thick black tar used to coat telephone poles. In order to survive, they have developed an altered AHR (aryl hydrocarbon receptor) pathway, so that they metabolize toxins differently from regular fish (this is a severely simplified explanation). While we know that Elizabeth River fish fare better against PAHs than King's Creek fish do, there haven't been many experiments conducted to see if Elizabeth River fish are resistant to other toxins, like metal ions. Therefore, my project will be on how well Elizabeth River fish exposed to silver do in comparison to those from non-polluted sites like King's Creek. We're dosing both embryos (unhatched eggs) and larva (~5 days post hatching) with a variety of forms of silver, including silver nitrate (AgNO3), and silver nanoparticles coated with citrate, gum-arabic, etc. We're not really sure what to expect yet; though we have no real reason to believe that the Elizabeth River fish will fare better since they haven't been extensively exposed to silver before, it's possible that their PAH resistant AHR pathway may confer some resistance to other substances too. On the other hand, it is also possible that because the Elizabeth River fish are resistant to one toxin, they will be more sensitive to other ones, and example of a fitness cost. And of course, it may turn out that both populations are equally susceptible to silver poisoning (in which case I may switch projects). I guess we'll just have to wait and see!
