The aim of this study is to establish short term ivermectin exposure conditions (STIECs) for the wild type Canton-S strain of Drosophila melanogaster and to determine if the flies treated with ivermectin under the STIECs produce elevated levels of reactive oxygen species (ROS) in their ovaries, leading to the overproduction of malondialdehyde (MDA) and enhanced DNA damages in fly ovaries. A glass vial contact bioassay was performed using six different concentrations of ivermectin (1 × 10 –6–1 × 10–1%) to establish the STIECs for female flies to survive and produce viable eggs during and after the ivermectin exposures. Based on the mortality bioassay results and statistical analyses, exposures to different concentration of ivermectin for less than 12 hr were determined to be the STIECs. Flies exposed to ivermectin under the established exposure condition were able to produce viable eggs with a mean hatchability of 78.9 to 96.1%. Percent hatchabilities of F1 flies were similar to control flies (ANOVA, p > 0.05). Female locomotor assays were performed in the presence of ivermectin using Drosophila activity monitoring (DAM) system. Regardless of experimental start time (8:00 AM or 8:00 PM) flies treated with ivermectin under the STIECs showed a decreasing trend of locomotor activities as ivermectin concentration increased. Levels of hydroxyl radicals in ovaries of ivermectin exposed flies were assessed to determine if ivermectin enhanced oxidative stress in ovaries of female flies. Ivermectin concentration and treatment time dependent increase in hydroxyl radicals was observed in ovaries of ivermectin exposed flies (F test, p < 0.05). Furthermore, thiobarbituric acid reactive substances (TBARS) assays to determine the level of MDA, a lipid peroxidation product, in ovaries of female flies. Concentration and time dependent accumulation of MDA was determined in ovaries from flies treated with ivermectin (F test, p < 0.05). Finally, single cell gel electrophoresis (SCGE) or comet assay was performed to determine the DNA damage in ovaries of ivermectin exposed female flies. Ivermectin concentration dependent DNA damage was determined in ovaries of flies treated with ivermectin 12 hr (F test, p < 0.05). Increased production of MDA likely enhanced the DNA damage as it is known to produce DNA adducts. DNA damage in ovaries of exposed flies may lead to the hypermutations. Further studies are required to identify mechanisms and roles if ivermectin induced hypermutations.
|Advisor:||Yoon, Kyong S.|
|Commitee:||Fowler, Tom, Greenfield, Ben, Williams, Jake, Yoon, Kyong S.|
|School:||Southern Illinois University at Edwardsville|
|School Location:||United States -- Illinois|
|Source:||MAI 57/06M(E), Masters Abstracts International|
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