Document Type

Thesis

Date of Degree Completion

Fall 2010

Degree Name

Bachelor of Science

Committee Chair

Dr. Lucinda Carnell, Department of Biological Sciences

Second Committee Member

Dr. Daniel J. Selski, Department of Biological Sciences

Third Committee Member

Dr. Audrey D. Huerta, Director Science Honors Research Program

Abstract

Electrotaxis can be observered in Caenorhabditis elegans (C. elegans) in response to an electric field stimulus. C. elegans will orient and travel in a straight uninterrupted path directly towards the negative pole of a DC electric field (Sukul and Croll 1978). In addition, two novel electric field responses in C. elegans have been uncovered in these studies: an initial increase in velocity to field stimulus, and an immediate reversal upon a decrease in field strength. In examining the neutral basis for this behavior we have identified a mutant, eat-4, defective in a transporter that packages glutamate into synaptic vesicles; that is severely disrupted in all three aspects of electrotaxis behavior: velocity, direction sensing, and reversals. Use of transgenic animals with neuron-specific rescue of the wild-type eat-4 gene has revealed a role for the amphid sensory neuron (AWC) in both velocity and sensing direction, but not in reversal behavior. The return of wild-type EAT-4 in both sensory neurons AWC and ASK completely disrupts recovery of AWX suggesting that ASK may function to inhibit the AWC-dependent pathway. This work has shown that electrotaxis in C. elegans consists of a neural circuit with multiple sensory neurons, interneurons and motorneurons. This behavior may provide a valuable insight into sensory integration of sensory stimuli into a moto behavior.

Comments

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