Semester of Graduation

Fall 2017

Degree

Master of Science (MS)

Department

Renewable Natural Resources

Document Type

Thesis

Abstract

Eastern oysters (Crassostrea virginica), native to the Gulf of Mexico, are keystone species in estuarine ecosystems and are economically valued. Current research indicates that ocean acidification adversely affects the physiology and morphology of larval oysters, but the molecular mechanisms of this impact remain unstudied. Ocean acidification is contributed to by elevated atmospheric CO2 due to increased anthropogenic activities, causing heightened partial pressure of CO2 (pCO2), and eutrophication from land-based runoff in the Gulf. The objective of this work was to determine the genomic response of the eastern oyster in Louisiana to simulated ocean acidification. In this study four biomineralization-related genes were cloned in C. virginica: caltractin (cetn), calmodulin (calm), calreticulin (calr), and calnexin (canx). The relative expression of these genes in response to changes in environmental pCO2 concentrations was analyzed both in vivo utilizing larval oysters and in vitro mantle cell culture models. Results revealed that larval oysters cultured in increased CO2 environments had reduced mean shell length and survival in comparison to those reared in ambient conditions. Expression levels of all four calcium-binding protein genes were altered in both larvae and mantle cells exposed to elevated pCO2, or hypercapnia conditions. Relative expression of calcium-binding proteins was representative of gene expression in both larvae and cells. The expression profiles of the calcium-binding protein encoding genes were correlated to the changes of pCO2 concentrations in the environment, which suggests critical roles of these proteins in the early biomineralization in C. virginica in response to ocean acidification. This study also validated the use of primarily cultured mantle cells as an effective model for investigating the impacts of environmental stressors on biomineralization mechanisms in C. virginica on the molecular level to predict the physiological responses of these organisms to future acidified conditions in the wild.

Date

11-13-2017

Committee Chair

Xu, Wei

Available for download on Tuesday, November 13, 2018

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