Discipline: Biological Sciences
Subcategory: Chemistry (not Biochemistry)
Jamisha Francis - University of the Virgin Islands
Co-Author(s): Paul Jobsis, University of the Virgin Islands
Ciguatera fish poisoning (CFP), the most common marine non-bacterial food poisoning in the world. There is a reported number of about 3 of every 1,000 people poisoned in the Virgin Islands (VI) with CFP. The number of cases not reported have not been included however it’s suspected that there are more cases. CFP in the VI is caused by the consumption of local reef fish that have consumed other fishes with the toxin present. Small fish consume the micro algae dinoflagellate, Gambeirdiscus toxicus species that is the known to produce the ciguatoxin (CTX) in its cells. CTX is known to bio-accumulate in fish tissue; top predator fishes usually have the highest concentrations. Sharks are the exception; sharks have an enzyme that can break down the CTX. CTX is composed of a long chain of fused polycyclic polyethers. Cyclic molecules usually fluoresce; this led us to attempt to measure the fluorescence spectrum of fish to look at differences between toxic and non-toxic fish spectra. Cero Mackerel was used as the known toxic sample because someone who consumed this fish was reported sick. Tilapia was used as a control in this study because tilapia is not known to be ciguatoxic. Barracuda was used as the unknown because it’s a top predator fish in VI local waters. Fish tissue samples were collected from fish fillets, avoiding the red bloodline. Tissue samples were mashed with water at a 2:1 ratio in a mortar and pestle. 3 µl of the supernatants were analyzed using a Cary Fluorescence Spectrometer. Emission spectrum was scanned using a 5±2.5 nm slit width from 380 to 620 wavelengths. Files were saved using comma separated values (CSV) and exported to excel to analyze and compare data. After data comparison, we noted the similarities between Barracuda and Tilapia at wavelengths peaks of 420±2.5 and 500±2.5. In the Cero Mackerel however, we noted the same peaks at both 420±2.5 and 500±2.5, but there was also peak at 460±2.5. Barracuda being one of the top predator fish in the VI we suspected that this spectrum would be similar to that of the Cero Mackerel however it wasn’t. The similarities in the Tilapia and Barracuda in-situ samples led us to believe that there is a possibility that fluorescence spectroscopy could be used to identify the presence of CTX in fish tissue. However, this was not a definitive study, only one of each fish species were used in this experiment. Future work has to be done to confirm that the fluorescence that we observed was indeed the CTX. Collaboration with other ciguatera researchers and additional fish samples could be used to further this study. Even though there is a noticeable difference between the suspected toxic fish and the non-toxic fish spectra we can’t confirm which form of CTX was fluoresced. Tissue samples used in this study have been sent to the mainland to confirm the presence of CTX. The results from this study may help lower the number of reported and non-reported cases of CTX in the VI.
Funder Acknowledgement(s): This project was funded by NSF VI-EPSCoR grant 0814417.
Faculty Advisor: Paul Jobsis, firstname.lastname@example.org
Role: For this project I did majority of the work. This includes majority of the literature research, methodology and all of the spectroscopy of tissue samples using a Cary Fluorescence Spectrometer. All fish tissue spectrum were analyzed by my mentor and I.