Date of Award

8-1-1996

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Biology

First Advisor

Dr. Bruce Chase

Abstract

Two specific receptor subtypes for octopamine, a biogenic amine found in both vertebrates and invertebrates, have been pharmacologically defined in insects. These receptors mediate responses involved in the regulation of movement, feeding and mating behaviors by inducing a rise in intracellular cAMP levels via adenylate cyclase stimulation or by increasing intracellular calcium levels via an undetermined mechanism. Recent studies on a putative octopamine/tyramine Drosophila receptor cDNA permanently expressed in mammalian cells have suggested the existence of an additional novel octopamine receptor subtype. This receptor binds multiple agonists (i.e. octopamine and tyramine) and can differentially couple to two different secondary messenger systems (i.e. Gi and Gq). Unlike classical octopamine receptor subtypes (i.e. octopamine1 and octopamine2), this receptor attenuates adenylate cyclase activity. To study further this receptor in Drosophila, the spatial distribution of its mRNA was determined by in situ hybridization. The probe was a 35S-labeled riboprobe derived from a 596 bp cDNA subclone encoding the third intracellular loop of this receptor. The expression sites for mRNA transcripts were identified in intact tissue sections (8-10µ) of larvae and adult flies using tissue autoradiography and analyzed under brightfield and darkfield microscopy. mRNA transcripts were localized in neuronal tissues of the larvae and adult fly, as well as in non-neuronal tissues of the larvae. This localization is consistent with the proposed roles for octopaminergic systems in Drosophila.

Comments

A Thesis Presented to the Department of Biology and the Faculty of the Graduate College University of Nebraska In Partial Fulfillment of the Requirements for the Degree Master of Arts University of Nebraska at Omaha. Copyright 1996 Laura M. McKay.

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