Date of Award

2015

Document Type

Thesis

Degree Name

Master of Science

School

College of Arts and Sciences

Program

Biology MS

First Advisor

Benjamin Navia

Second Advisor

John Stout

Third Advisor

Jim Hayward

Abstract

Juvenile Hormone III (JHIII) is a prolific and essential hormone in insects, controlling many aspects of insect physiology such as egg development, nymphal and larval maturation, diapause and metamorphosis. In female crickets, Acheta domesticus, JHIII increases selectivity in phonotactic behavior, narrowing phonotactic choices for Syllable Periods (SPs) of the Calling Songs (CSs) that most closely resemble the natural call of the male. JHIII has been suggested to work through a pathway that activates the protein kinase C (PKC) molecule. Chelerythrine Chloride (CC) is a potent inhibitor of PKC action. This study analyzes the responses of the L3 auditory interneuron, which has been suggested as an important neuron in the prothoracic ganglion for filtering CSs and inducing phonotaxis, in response to JHIII and CC. We recorded neuronal responses extracellularly before and after nanoinjection with JHIII and CC in order to analyze the molecular effects of the two substances on the selective processing of the L3 neuron. JHIII increases SP-selective decrement in a subgroup of our crickets by significantly reducing decrement at the shortest SPs (30 and 40 ms) and centering the response around the SPs most similar to the natural call. It has no effect on a smaller, subgroup of crickets. CC decreases the selectiveness of decrement in L3. It is suggested that both the mechanism for sharpening the females’ phonotactic behavior is expressed through molecular pathways in the L3 neuron, and that JHIII carries out at least part of its effects on the L3 neurons through a PKC mediated pathway, the effects of which can be reversed or blocked following treatment with CC.

Subject Area

Juvenile hormones, Crickets--Effect of sound on, Crickets--Behavior, Protein kinases

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