Date of Award

8-2014

Rights

© 2014 Christopher Goodchild

Document Type

Thesis

Degree Name

Master of Science in Marine Sciences

Department

Marine Science

First Advisor

Stephen Zeeman

Abstract

Although biomarkers are frequently used to assess sublethal effects of contaminants, a lack of mechanistic linkages to higher-level effects limits the predictive power of biomarkers. Bioenergetics has been proposed as a framework for linking cellular effects to whole-animal effects. We investigated sublethal effects of exposure to wastewater treatment facility effluent in freshwater mussels in situ, thereby capturing ecologically relevant exposure conditions. Our study focused on the energetic biomarker AMP-activated protein kinase (AMPK), while also considering more traditional biomarkers like heat shock proteins (HSP70), and antioxidant enzymes (i.e., superoxide dismutase (SOD), glutathione-S-transferase (GST)). We examined biomarkers at mRNA and protein levels. Effluent exposure caused a reduction in total-AMPK protein abundance (p = 0.05) and AMPK mRNA expression (p = 0.02). Conversely, AMPK activity increased at downstream sites by 2.2-fold (p = 0.05), indicating increased cellular energy consumption. HSP70 protein abundance was lower at downstream sites (p < 0.05), while SOD and GST activity levels significantly increased. By using various biomarkers, we demonstrate that exposure to municipal effluent creates an energetically taxing situation. This is the first study to use AMPK to evaluate the effects of contamination in situ, and our results suggest that energetic biomarkers, like AMPK, complement traditional biomarkers and may help establish functional links between cellular and whole-animal effects.

Comments

Master's thesis

This digital object has been funded in part with Federal funds from the National Science Foundation, Division of Graduate Education, under Award No. #0841361, "The Interactions of Biology, Chemistry and Physics at the Land-Ocean Interface: A Systemic PARTnership Aimed at Connecting University and School (SPARTACUS)", to the University of New England.

Chapter one of this thesis was the basis for the following publication:
Goodchild CG, Frederich M, Zeeman SI. 2015. AMP-activated protein kinase is a biomarker of energetic status in freshwater mussels exposed to municipal effluents. Science of the Total Environment. 512:201-209. DOI:10.1016/j.scitotenv.2015.01.065

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