A P-glycoprotein-like mechanism in the nicotine-resistant insect, Manduca sexta.
type: CreativeWork
description: The phenomenon of multi-drug resistance in tumor cells is mediated by the overexpression of a membrane protein called P-glycoprotein. Since its initial discovery in tumor cells, P-glycoprotein-like molecules have been found to transport a wide range of substrates in organisms from microorganisms to humans. To test the hypothesis that a P-glycoprotein-like mechanism is operating in insects, three insect species were used: Manduca sexta, Periplaneta americana and Rhodnius prolixus, the nicotine-resistant M. sexta was the model toxin-resistant insect. Immunostaining with a monoclonal antibody, C219, which recognizes a highly conserved epitope in all P-glycoprotein molecules, demonstrated positive immunolabelling of the Malpighian tubules of M. sexta and R. prolixus and at the blood-brain barrier of the central nervous systems of M. sexta and P. americana. To assess the extent of P-glycoprotein involvement at the blood-brain barrier of M. sexta, I took advantage of the three different stages of the insect's life cycle, the actively feeding larval stage and the non-feeding pupal and adult stages. Using an extracellular recording technique to monitor levels of neural activity in isolated abdominal nerve cords, I demonstrated that, in contrast with larval M. sexta, the CNS of both the pupal and adult stages are both highly nicotine-sensitive. Immunostaining for P-glycoprotein in the metamorphosing CNS illustrated that the distribution of P-glycoprotein in the barrier region changes dramatically when the need for a barrier to dietary neurotoxins is lost. M. sexta Malpighian tubules provided an ideal in vitro assay system to directly test our hypothesis that a P-glycoprotein-like molecule is involved in nicotine transport. Using an isolated Malpighian tubule preparation, the tubules were assayed for their ability, first, to concentrate nicotine in the tubule lumen (confirming the presence of an active transporter in the tubules) and, second, to determine if various drugs int…
abstract: The phenomenon of multi-drug resistance in tumor cells is mediated by the overexpression of a membrane protein called P-glycoprotein. Since its initial discovery in tumor cells, P-glycoprotein-like molecules have been found to transport a wide range of substrates in organisms from microorganisms to humans. To test the hypothesis that a P-glycoprotein-like mechanism is operating in insects, three insect species were used: Manduca sexta, Periplaneta americana and Rhodnius prolixus, the nicotine-resistant M. sexta was the model toxin-resistant insect. Immunostaining with a monoclonal antibody, C219, which recognizes a highly conserved epitope in all P-glycoprotein molecules, demonstrated positive immunolabelling of the Malpighian tubules of M. sexta and R. prolixus and at the blood-brain barrier of the central nervous systems of M. sexta and P. americana. To assess the extent of P-glycoprotein involvement at the blood-brain barrier of M. sexta, I took advantage of the three different stages of the insect's life cycle, the actively feeding larval stage and the non-feeding pupal and adult stages. Using an extracellular recording technique to monitor levels of neural activity in isolated abdominal nerve cords, I demonstrated that, in contrast with larval M. sexta, the CNS of both the pupal and adult stages are both highly nicotine-sensitive. Immunostaining for P-glycoprotein in the metamorphosing CNS illustrated that the distribution of P-glycoprotein in the barrier region changes dramatically when the need for a barrier to dietary neurotoxins is lost. M. sexta Malpighian tubules provided an ideal in vitro assay system to directly test our hypothesis that a P-glycoprotein-like molecule is involved in nicotine transport. Using an isolated Malpighian tubule preparation, the tubules were assayed for their ability, first, to concentrate nicotine in the tubule lumen (confirming the presence of an active transporter in the tubules) and, second, to determine if various drugs int…
author: Murray, Christine L.
keywords: Biology, Entomology.
identifier: Source: Dissertation Abstracts International, Volume: 58-04, Section: B, page: 1653.
date published: 2009-03-25T20:01:35Z
date modified: 2026-07-24T03:39:34Z
provider: University of Ottawa
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Ottawa (Canada)

PropertyValue
property ID: Handle
value: http://hdl.handle.net/10393/10057

PropertyValue
property ID: DOI
value: 10.20381/ruor-16632