Masters Thesis

Declines in behavior and cognition when tau is expressed at different times in the adult drosophila melanogaster brain

This study involved Drosophila melanogaster, the common fruit fly, as the model organism to study the behavioral differences seen in flies overexpressing the human tau protein throughout their adult life span. The tau protein (MAPT – microtubule associated protein tau) is linked to Alzheimer’s Disease (AD). It is seen in both humans and Drosophila and has been noted to decrease learning and cognitive abilities in both. This study aimed to look at the cognitive and behavioral difference seen as adult flies age. The adult flies were tested at three different ages (young, middle, elderly) in order to look for any progression declines in behavior as the flies aged and expressed the human tau for longer periods of time. The human tau was driven into two different areas of the brain (ellipsoid body, mushroom body) that have been shown to be important regions for learning and memory in insects. The flies were tested in two different behavioral assays, a visual place learning assay and a negative geotaxis assay, in order to quantify spatial learning and memory. Additionally, fluorescence microscopy was used to analyze the amount of tau present in the brain at different times of the adult’s life, which confirmed the increased expression of tau as flies aged. As tau-expressing flies aged, both visual place learning and memory were impacted. These flies also showed a decline in planning ability. The behavioral declines seen in this study can be correlated to patients with AD who also overexpress this abnormal tau protein. This study aims to create a better Drosophila melanogaster model for AD. Moreover, the findings of this study can contribute to a better model organism for AD, which allow us to test interventions prior to the onset of dementia.