The effects of manganese on the behavior of Drosophila melanogaster The objective of my project is to determine the effects of manganese (Mn) on the behavior of Drosophila melanogaster using three experiments, testing fecundity (amount of offspring), locomotion, and group mating. Although Mn is an important element for maintaining homeostasis, it can be toxic when organisms are exposed to large amounts—this is called manganism (Zoni et al., 2007, 812). Manganism is classified as a form of Parkinson’s disease. The organism D. melanogaster was used because previous research showed that it is a good genetic model for Parkinson’s disease (Hattori & Sato, 2007, 479). The most common overexposures to Mn occur in people who work in areas in which high levels of Mn are in the environment. This is particularly relevant because the Mid-Ohio Valley has the only Mn refinery in the United States, Eramet (“Levels of manganese...”, 2008, 1). In 2009 the areas’ Mn level was 23 times higher than the EPA’s guidelines (Morrison & Heath, 2010, 1). The hypothesis is that the D. melanogaster will be affected by the manganese burden which will cause behavioral differences. The group exposed to the largest amount of manganese will exhibit the most extreme effects—in decreased courtship, fecundity, and locomotion, from that of the control group. Materials & Methods Methods were modified from Hirsh et al., Vestigial Drosophila melanogaster were maintained on 3 g of dry weight Ward’s Instant Drosophila Medium- Blue with four treatment groups using 15mL of dH 2 O (control), and three groups at 0.05mg/L, 0.5mg/L, and 5.0mg/L of Mn2 chloride 4-hydrate. Two weeks later flies emerged ready to be used. For the fecundity experiment, a male and female from the same treatment group were put into a vial with control medium and after 24 hours the male was removed. The male was distinguished from the female by its smaller size, sex combs on front legs, and darker abdomen. The female was then transferred to a new vial of control medium until day 3 and was moved again to a new vial until day 7. The offspring were then counted. In the locomotion experiment, a fly was placed into a petri dish with a 1 cm grid attached. After 30 seconds, the number of gridlines crossed were counted. This was done for 20 males and 20 females at each treatment level. In the group mating experiment, 5 males and 5 females from the same treatment group were put onto control medium, with the amount of flies mating recorded. Finally, the Mn burden was determined by using atomic absorption spectrometry. Results. Figure 2. Average locomotion of 20 males and 20 females at each exposure level. Figure 4. The Mn burden of the flies at each exposure level using atomic absorption spectroscopy. Acknowledgements I would like to thank my advisor Dr. Lustofin, Dr. Brown, my capstone classmates, and the entire MC biology department for funding and supporting my project Introduction Literature Cited Conclusions Lauren McKiernan Advisor: Dr. Lustofin Figure 1. Average number of total offspring at each of the exposure levels N= number of vials at each exposure level. Figure 3. Amount of pairs that mated out of the 10 flies at each exposure level. Flies exposed to higher levels of manganese had more offspring (Figure 1). This goes against my hypothesis. I had difficulty getting the flies to breed, possibly due to the one on one nature of the experiment, the drying out of some of the media, or experimental error. Due to a lack of usable vials, I was unable to perform statistical analysis on the data. The locomotion experiment showed that there was no statistically significant difference in the number of gridlines crossed in 30 seconds by the control group and the groups raised with Mn in the media (Figure 2). There was a trend showing that higher exposure groups moved less, but this was not significant (p = 0.059). Although only 1 replica was completed in group mating, it suggested a trend that higher levels of Mn cause a decrease in group mating (Figure 3). More trials would need to be completed to see if this is statistically significant. The amount of Mn found in the D. melanogaster increased as the concentration of Mn in the diet increased (Figure 4). Even though the data agrees with previous research which shows that Mn has an effect on the behavior of D. melanogaster, no conclusions could be drawn based on the results (Zoni et al., 2007, 813). My fecundity test did not supply any usable data so no comparisons could be made between the exposure levels. The locomotion showed a trend towards higher exposure groups moving less, but with no significance. For the group mating experiment, only 1 trial was able to be performed, so more trials would need to be ran to see if the results were significant. Hopefully, this research can be continued to further the knowledge of the effects of Mn on other organisms, including humans. Fact Sheet: What you need to know about Manganese in Drinking Water. July Connecticut Department of Public Health. February 24, Hattori, Nobutaka and Sato, Shigeto Animal models of Parkinson’s disease: Similarities and differences between the disease and the models. Neuropathology 27: Hirsh, Helmut VB; Mercer, John; Sambaziotis, Hera; Huber, Michael; Stark, Diane T.; Torno-Morley, Tara; Hollocher, Kurt; Ghiradella, Helen; Ruden, Douglas M Behaviour Effects of Chronic Exposure to Low Levels of Lead in Drosophila melanogaster. Neurotoxicology 24: Morrison & Heath. EPA vows to do all it can for school’s air. January 1, Shawver, Sam. Levels of manganese in air above EPA guidelines at times. February 5, Marietta Times. February 25, Wallace, EM. “Watercolor illustration of Drosophila melanogaster.” C.B. Bridges & T.H. Morgan: Contributions to the genetics of Drosophila melanogaster. (278): April 14, < 12/ci-ssc php>. Zoni S; Albini E; and Lucchini R Neuropsychological Testing for the Assessment of Manganese Neurotoxicity: A Review and a Proposal. American Journal of Industrial Medicine 50: