Behavioral and genetic dissection of polarotactic responses in Drosophila melanogaster
- Mariel Velez.
- June 2011.
- Physical description
- online resource (xiii, 87 pages) : illustrations (chiefly color)
- Velez, Mariel Marques.
- Clandinin, Thomas R. (Thomas Robert), 1970- thesis advisor (primary).
- Fernald, Russell D. thesis advisor.
- Luo, Liqun, 1966- thesis advisor.
- Wandell, Brian A. thesis advisor.
- Stanford University. Committee on Graduate Studies. degree grantor.
- Stanford University. Neurosciences Program.
- Includes bibliographical references (p. 78-87). 82 refs.
- Polarized light plays a prominent role in shaping navigational decisions and course control in a variety of insects. Work in ants, crickets and bees have highlighted the importance of a specialized subset of ommatidia in the dorsal rim of the retina, the DRA, in detecting these signals. However, the retina's full capacity to detect polarized light has not been probed, nor are the behavioral mechanisms by which animals respond to such cues known. We have developed a novel, fully-automated behavioral paradigm for detecting polarotactic responses in Drosophila, and have used genetic and behavioral approaches to address these issues. We demonstrate that when polarized UV light stimuli are displayed to populations of Drosophila, animals align their body axis with the e-vector of plane polarized light. Surprisingly, while photoreceptors in the DRA can indeed guide this behavioral response, other photoreceptors distributed across the retinal surface can do so as well. We show that that one class of UV sensitive photoreceptors, those expressing the Rh3 opsin, is both necessary and sufficient for mediating polarotactic behavior. In particular, flies in which only Rh3 expressing photoreceptors are functional can respond to UV polarized light, while inactivation of these cells blocks polarotactic behavioral responses. Moreover, ectopic expression of a green-light sensitive opsin in Rh3 expressing cells allows flies to acquire the capacity to respond to green polarized light. Detailed behavioral studies demonstrate that the ability of flies to align to the e-vector occurs via a stereotyped modulation of the flies' rotational velocity and acceleration as a function of their angular position relative to the e-vector. These studies define the precise computations necessary to explain the behavior, and provide insight into the organization of the neural circuitry that links polarized light signals to course control.
- Publication date
- Submitted to the Department of Neurosciences and the Committee on Graduate Studies of Stanford University.
- Thesis (Ph.D.)--Stanford University, 2011.