Document Type
Thesis
Degree Name
Master of Science (MSc)
Department
Biology
Program Name/Specialization
Integrative Biology
Faculty/School
Faculty of Science
First Advisor
Jonathan Mark Wilson
Advisor Role
Advisor
Abstract
The vertebrate stomach, characterized by acid-peptic digestion, is a specialized evolutionary adaptation enhancing digestion. Acid secretion is dependent on the heterodimeric gastric proton pump (H+/K+-ATPase; HKA), encoded by the genes atp4a and atp4b. Atp4a is the catalytic subunit, and Atp4b has roles in membrane targeting and complex stability. The emergence of the stomach led to an extension of available protein sources, and an array of advantages including an innate immune defense against pathogens entering the GIT and improved cell lysis. Despite the advantages associated with a gastric phenotype, the dynamics of the two HKA subunits remain to be fully understood, especially in the context of the secondary loss of gastric acidification observed in a quarter of teleost species. We have previously established an atp4a knockout in Astyanax mexicanus and described the phenotype, focused on metabolism, modulation of atp4b expression, and HKA membrane trafficking. In this study, we have generated an atp4b crispant (rapid, F0 generation, somatic knockout) in A. mexicanus using CRISPR-Cas9 gene editing to investigate the roll of Atp4b in gastric physiology, cell dynamics and, particularly, the modulation of the expression and membrane recruitment of Atp4a. Crispant fish exhibited a significant increase in gastric pH, and down regulation of genes associated with gastric function. Immunohistochemistry further revealed that Atp4a and Atp4b both underwent a reduction of apical localization in gastric glands, highlighting the role of Atp4b in HKA membrane targeting. As a consequence of disrupted gastric function, crispants had impeded protein catabolism, however, no changes to body composition. Ultimately, this project advances our understanding of the physiology of gastric secretion and provides insights into the drivers and consequences underlying stomach loss in fishes.
Recommended Citation
Seguin, Aiden CR, "Structural Support or Functional Necessity: Evaluating the importance of the gastric proton pump β-Subunit in gastric function using gene knockout." (2027). Theses and Dissertations (Comprehensive). 2985.
https://scholars.wlu.ca/etd/2985
Convocation Year
2027
Convocation Season
Spring
Included in
Cellular and Molecular Physiology Commons, Comparative and Evolutionary Physiology Commons