Date of Completion

Spring 5-1-2015

Thesis Advisor(s)

Eric Schultz

Honors Major

Ecology and Evolutionary Biology

Disciplines

Ecology and Evolutionary Biology | Genetics and Genomics

Abstract

Na+, K+-ATPase (NKA) a1a and a1b expression was investigated in Alewives in response to salinity challenge. Anadromous and landlocked Alewives were exposed to freshwater (0ppt) and seawater (30ppt) treatments and sampled at 2-, 5-, and 15-day time points. Anadromous alewives exhibit significant up-regulation of a1a in freshwater compared to seawater at all time points, and significant up-regulation of a1b in seawater compared to freshwater at all time points. In landlocked Alewives, a1a is significantly up regulated at the 5-day time point and a1b is significantly up regulated at all time points (in their respective salinities). Analysis of the ratio of a1b to a1a expression reveals a significant effect of salinity in both populations, and additionally a salinity by day interaction in the anadromous population. This significant expression difference between the isoforms denotes isoform switching in Alewives. Molecular phylogenetics performed using Geneious R8 with the Mr. Bayes plug-in show a single divergence evolution of the NKA isoforms in salmonids, but separate origins for the Alewife isoforms that may predate evolution in salmonids. Results of this study indicate that NKA a1a and a1b are present in Alewives and exhibit isoform switching in both anadromous and landlocked populations. Also, evidence shows that the evolutionary history of the isoforms may differ between taxa. Further studies should be done to investigate the presence of these isoforms in other species and create a more encompassing molecular phylogeny.

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