Methylmercury In Zebrafish

Mercury is a naturally occurring heavy metal that can be transported through the atmosphere and transformed into a toxic, organic compound. Anthropogenic and natural determinants can lead to the bioaccumulation of methylmercury in the tissues of aquatic organism, leading to non-lethal affects. This chemical can also biomagnify in the tissue of organisms at higher trophic levels (Zillioux et al., 1993). Activities caused by humans such as the burning of fossil fuels, coal along with the manufacturing of degradation soil each assist in the accumulation of mercury in the environment. Hg can travel thousands of miles throughout the atmosphere from its original source, contaminating unaffected bodies of water where it can then be absorbed and ingested
These fish are extremely accommodating when constructing research on developmental effects, due to their high rate of fertility. Not only are they cost efficient but they also easy to cultivate in a laboratory. In this current study, two groups of zebrafish were fed different environmentally relevant concentrations of methylmercury for a total of 60 days to determine if similar changes in gene transcription could be observed in zebrafish as previously observed in fathead minnows (Klaper et al., 2006). When comparing the control group to the group contaminated with methylmercury, the protein structure was damaged. At which the concentration that was given to the zebrafish only a small dose was required to show a significant effect. In addition, because each region of the brain has different functions, different sensitivities, and different constitutive gene expression, studies of whole brain will capture only changes that occur in large regions of the brain, or that occur in multiple regions
Gymnotus sylvius is a weak electric fish that emits low-voltage electric pulses at a discharge rate of 20-70 Hz (Moraes, 2012). Electric organ discharges (EODs) in the weak electric fish Gymnotus sylvius are produced by the electric organ and modulated by the CNS. Moraes (2012) examined uptake of methylmercury by injecting earthworms and feeding them to weak electric fish G sylvius. The fish were then exposed to different concentrations of MeHG for 18 days and tested using a oscilloscope. Moraes (2010) collected signals to determine the electric organ discharges. Results showed that the higher the dosage of MeHg, the higher the EOD rate. Although the MEHg concentration was not quantified in G. sylvius tissues, it likely reached the brain of the fish, leading to alterations in the neural control of the EOD rate (Moraes, 2012). The fine-tuning of the EOD rate is crucial for electrical communication among Gymnotus species, which determines reproductive and non-reproductive interactions and affects social and ecological aspects. (Gouvea Junior, Stopa, Paula & Hoshino,