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cellular imaging, Acid-base, transport, mitochondrion-rich cells, Fish

Parks, Scott Kenneth

Supervisor and department: Goss, Greg Biological Sciences

Examining committee member and department: McCormick, Stephen Biology, University of Massachusetts Amherst Duszyk, Marek Physiology Leys, Sally Biological Sciences Ali, Declan Biological Sciences

Department: Department of Biological Sciences

Specialization: Physiology, Cell and Developmental Biology

Date accepted: 2009-08-31T20:06:37Z

Graduation date: 2009-11

Degree: Doctor of Philosophy

Degree level: Doctoral

Abstract: I investigated cellular mechanisms of ion and acid-base transport in rainbow trout Oncorhyncus mykiss, crabs Neohelice granulata, zebrafish Danio rerio, Pacific hagfish Eptatretus stoutii, and mosquito larvae Aedes aegypti with a primary focus on discerning the mechanisms governing ion transport and acid base regulation. In rainbow trout I provide the first functional evidence for two physiologically distinct mitochondrion-rich MR cells at the gill and demonstrate a new model for transepithelial Na+ uptake from freshwater involving apical Na+ channels and basolateral Na+-HCO3- co-transporters. These data are supported by extensive thermodynamic consideration of Na+ uptake from freshwater. I also demonstrate functional Cl-HCO3- exchangers in both MR cell subtypes with roles for Cl- uptake and intracellular pH pHi regulation respectively and I present the first evidence for a Cl- dependent Na+-H+ exchanger in gill MR cells. Finally I demonstrate a unique Na+ dependent pHi recovery mechanism that requires protein kinase C for activation. A major limiting factor in clarifying the mechanisms of Na+ uptake in freshwater fish is the lack of a typical Na+ channel in any of the fish molecular databases. My work on zebrafish, although preliminary, indicates that a member of the acid-sensing ion channel family could be responsible for Na+ uptake from freshwater. I then expanded my research outside the trout model using an isolated crab gill preparation. I provide a cellular model for H+ secretion in crab gills that supports the transepithelial Na+ transport model that I described in rainbow trout. In Pacific hagfish, I demonstrate that recovery from blood acidosis is dependent on a Na+-H+ exchanger in gill MR cells. This mechanism of regulation involves translocation from the cytoplasm to the apical membrane during acidotic stress. This data combines with other studies demonstrating the mechanisms of acid and base secretion from a single MR cell subtype. Finally, I show that serotonin stimulation alkalinizes the pHi of the anterior midgut cells in the larval mosquito to levels never before observed in cell biology. These data challenge the dogma of pHi regulation in cell biology and demonstrate the power of using a comparative approach to systems physiology.

Language: English

DOI: doi:10.7939-R3C59D

Rights: Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.

Autor: Parks, Scott Kenneth

Fuente: https://era.library.ualberta.ca/


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