Effects of age and environment on locomotor performance in adult Drosophila melanogaster
Drosophila melanogaster has been an attractive animal model for more than 100 years. Our laboratory has established a high-throughput assay for fly locomotion in a circular arena. Fly locomotor activity involves the interaction between the environment and internal physiological characteristics, including age. Behaviors such as walking, feeding and resting are age-specific, however, how age affects the fly locomotion and whether such changes are strain specific is unclear. Environmental effects such as variation in temperature and humidity also affect locomotor performance. However, the effects on locomotion of long-term environmental change such as the pulsed light stimulation, or the short-term environmental change such as acute hypoxia, are unknown. For my thesis, I investigated the effect of age on locomotor performance by examining boundary preference, path length per minute and 0.2 s path increment during locomotion in small circular arenas, and the speed of locomotor recovery from anoxia. My results show that locomotor performance depended on age, and such age-dependent changes differed between fly strains. I also studied the effect of pulsed light stimulation on locomotor activity and extracellular electrical activity in the brain. This stimulus increased boundary preference and the distance travelled in a circular arena, as well as the periodicity of episodic motor activity. In addition, I examined locomotor responses to hypoxia and the role of CNGL channel in these responses. Hypoxia and re-oxygenation modulated locomotor performance, and flies with down-regulation of CNGL showed reduced locomotion under normoxia, reduced recovery from hypoxia, and reduced basal level of CNS extracellular K+ concentrations. In response to hypoxia, down-regulation of CNGL increased extracellular K+ concentration change, reduced time to reach the K+ concentration peak, and delayed time to recover from hypoxia. Upregulation of cGMP partially compensated for the changes in locomotor activity and electrophysiological alterations in response to hypoxia. Taken together, age and environmental stimuli affect fly locomotor performance, and CNGL channels are involved in modulating locomotion and CNS function in response to hypoxia in adult Drosophila.
URI for this recordhttp://hdl.handle.net/1974/15943
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