1. The effects of MnCl 2 on body burden and response time in Danio rerio (zebra fish) By: Ashley McDonald Introduction: Manganese is an essential microelement that plays an important role in many biological processes (Vezer et al, 2007, 841). Too much manganese can accumulate in the cell’s mitochondria which can impair oxidative phosphorylation and the production of ATP (Avila et al., 2010, 195). It can cause physical symptoms such as, tiredness, sleep disturbances, aggressiveness, and dystonia (Santos et al., 2010,153). Over-exposure to manganese can also lead to Parkinson’s disease-like symptoms (Ordonez-Librado et al., 2010, 81). Manganese is the fourth most widely used metal in the world and used in iron and steel production, manufacturing of dry cell batteries and glass, and lastly in matches and fireworks(Santamaria, 2008, 485). While manganese compounds are not volatile, they can exist as fumes, aerosols and suspended particulates (Aschner et al., 2005, 5). Some industries that produce ferroalloys, iron and steel foundries, welding fumes, battery productions, and lastly power plants and coke oven emissions emit manganese into the air (Aschner et al., 2005, 5). With the coal burning plant and other industrial plants in Marietta area, it is no surprise that the manganese levels are concerning. Zebra fish are used as a model organism for aquatic studies because of their small size, short generation times, and inexpensive maintenance (Bretaud et al., 2004, 858). The hypothesis was that zebra fish will exhibit dose-dependent neurotoxicity when exposed to aqueous MnCl 2. Methods: Four tanks were placed side by side with 30L of water in each tank, then 6 females and 4 males were placed into each tank. Each tank had a thermometer, heater, and filter in each tank. The temperature in each tank was 74-75  F and the pH was maintained at 7.4-7.8. The fish were exposed by placing MnCl 2 in to the tank water two hours prior to the addition of fish. This was done to insure that the MnCl 2 was evenly distributed throughout the tanks. The control tank contained no additional Mn, while the 25ppm tank contained 750mg/30L, 50ppm had 1,500mg/30L, and 75ppm tank had 2,250mg/30L. After 4 weeks of exposure, the fish were digested in acid using procedures provided by Dr. Brown (personal communication). The digested fish were then placed in to an atomic absorption spectrophotometer to determine the body burden in each fish. For trials 3 and 4 the fish were tested for neurotoxic effects. This was done by placing the fish into a tank with lines (see figure 1) and recording how many lines were crossed in 5 minutes. The number was then divided by 5 to get the average number of lines crossed in 1 minute. In trial 3, the fish were tested post-exposure only and in trial 4 the fish were tested pre and post-exposure. Results: Figure 3: Behavior assay results for trial 3. The lines represents the standard error. There is no significant difference between treatment groups (p=0.366). N=10. Figure 2: Behavior assay results for Trial 4. The lines represent standard error. There is no significant difference between the treatment groups (p=0.419). N=10. Figure 1: Line test tank. The lines that the fish swam across in 5 minutes were recorded and divided by 5. This gave the average lines crossed per minute. Results: There was no correlation between pre and post-behavior, p=0.419 (see figure 2). There was a large variation in number of lines crossed. This was due to some fish not crossing any lines and other fish crossing a larger number of lines than the average of the population. Treatment had no significant effect on behavior (see figure 3) with p=0.336. There was however, a significant difference in the 75ppm treatment when compared to the other treatments (p= 0.029). But there was no significant difference in body burden between the 25ppm and 50ppm when compared to the control (p=0.0001, p=0.04). Conclusions: The data did not support the hypothesis. One possibility could have been that the dosing in the treatments were not high enough to induce neurotoxicity. Another possibility is that the line testing tank (see figure 1) was not sensitive enough to capture subtle neurotoxic behaviors. Literature Cited: Aschner M, Erikson K, Dorman D. 2005. Manganese dosimetry: species differences and implications for neurotoxicity. Critical Review in Toxicology. 35: 1-32. Availa D, Colle D, Gubert P, Palma A. Puntel G, Manarin F, Noremberg S, Nascimento P, Aschner M, Rocha J, Soares F. 2010. A possible neuroprotective action of a vinylic telluride against Mn-induced neurotoxicity. Toxicological Sciences. 115(1): 194–201 Bretaud S, Lee S, Guo S. 2004. Sensitivity of zebrafish to environmental toxins implicated in Parkinson’s disease. Neurotoxicology and Teratology. 26:857-864. Ordonez J, Martinez V, Valdez A, Flores E, Corona D, Fong D, Costa M. 2010. L-DOPA treatment reverses the motor alterations induced my manganese exposure as a Parkinson disease experimental model. Neuroscience Letters. 471: 79-82 Santamaria A. 2008. Manganese exposure, essentiality and toxicity. Indian J Med Res. 484-500. Santos A, Milatovic D, Au C, Yin Z, Batoreu M, Aschner M. 2010. Rat brain endothelial cells are a target of maganese toxicity. Brain Research. 1326: 152-161. Tomas G. 2010. Maganese and Parkinson’s Disease: A critical review and new finds. Environmental Health Perspectives. 8(118): 1071-1080. Vezer T, Kurunczi A, Naray M, Papp A, Nagymajtenyi L. 2007. Behavioral effects of subchronic inorganic manganese exposure in rats. American Journal of Industrial Medicine. 50: 841-852. Acknowledgements: A special thanks to the Biology Department for funding my project, Biology Professors for all of their advice and help, and my friends and family for their unwavering support. Figure 4: Body Burden vs. Treatment. The lines represent the standard error. There was no significance between the control, 25ppm, and 50ppm. (p=0.001, p=0.04) while the 75ppm had a significance difference compared to the control (p=0.029). N=10.