University of Kentucky
Studies in Neurobiology: Study 1: The Effects of Serotonin on Circadian Pattern and Behaviors in Drosophila
Institution
University of Kentucky
Faculty Advisor/ Mentor
Robin Cooper; Sonya Bierbower
Abstract
It has been established that adult Drosophila show circadian patterns that are regulated by gene expression. Circadian cycles in adults can be induced and set by exposure to light as early as the embryo stage without any circadian patterns evident throughout the larval stages. I hypothesized that the maintenance of the circadian pattern throughout the larval stages can be modulated by altering the serotonin expression levels in the larvae. This in turn will then affect the adult circadian pattern. To approach this, I exposed larvae, at various stages, to a drug (p-CPA, 10mg/ml of food) that blocks the synthesis of serotonin and then examined circadian patterns in adults. Adults were tested on 12:12 light:dark cycle and in continuous darkness. I also assayed whole animal adult behaviors (i.e., response to light and righting reflex) in controls and larvae that were fed p-CPA. In order to measure circadian patterns, I built a device to measure activity of adults as individuals and groups. The fundamentals of the device were an IR light source with a detector monitored by an online program. The results of feeding larvae p-CPA led to a more distinctive circadian pattern, which was contrary to my hypothesis. As adults, the p-CPA fed larvae showed a slower climbing response to light (p<0.05, n=15, t-test). Associative learning assays showed that the p-CPA fed larvae showed a more pronounced learning. The p-CPA fed larvae had a compromised immune system. In summary, p-CPA fed larvae had altered circadian patterns and behaviors as adults.
Studies in Neurobiology: Study 1: The Effects of Serotonin on Circadian Pattern and Behaviors in Drosophila
It has been established that adult Drosophila show circadian patterns that are regulated by gene expression. Circadian cycles in adults can be induced and set by exposure to light as early as the embryo stage without any circadian patterns evident throughout the larval stages. I hypothesized that the maintenance of the circadian pattern throughout the larval stages can be modulated by altering the serotonin expression levels in the larvae. This in turn will then affect the adult circadian pattern. To approach this, I exposed larvae, at various stages, to a drug (p-CPA, 10mg/ml of food) that blocks the synthesis of serotonin and then examined circadian patterns in adults. Adults were tested on 12:12 light:dark cycle and in continuous darkness. I also assayed whole animal adult behaviors (i.e., response to light and righting reflex) in controls and larvae that were fed p-CPA. In order to measure circadian patterns, I built a device to measure activity of adults as individuals and groups. The fundamentals of the device were an IR light source with a detector monitored by an online program. The results of feeding larvae p-CPA led to a more distinctive circadian pattern, which was contrary to my hypothesis. As adults, the p-CPA fed larvae showed a slower climbing response to light (p<0.05, n=15, t-test). Associative learning assays showed that the p-CPA fed larvae showed a more pronounced learning. The p-CPA fed larvae had a compromised immune system. In summary, p-CPA fed larvae had altered circadian patterns and behaviors as adults.