Table of Contents
International Journal of Evolutionary Biology
Volume 2015 (2015), Article ID 538918, 11 pages
http://dx.doi.org/10.1155/2015/538918
Research Article

The Evolutionary History of Daphniid α-Carbonic Anhydrase within Animalia

1Program in Ecology & Evolutionary Biology, Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA
2University of Oklahoma Biological Station, 15389 Station Road, Kingston, OK 73439, USA
3Murray State College, One Murray Campus, Tishomingo, OK 73460, USA

Received 5 October 2014; Revised 12 March 2015; Accepted 14 March 2015

Academic Editor: Hirohisa Kishino

Copyright © 2015 Billy W. Culver and Philip K. Morton. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Understanding the mechanisms that drive acid-base regulation in organisms is important, especially for organisms in aquatic habitats that experience rapidly fluctuating pH conditions. Previous studies have shown that carbonic anhydrases (CAs), a family of zinc metalloenzymes, are responsible for acid-base regulation in many organisms. Through the use of phylogenetic tools, this present study attempts to elucidate the evolutionary history of the α-CA superfamily, with particular interest in the emerging model aquatic organism Daphnia pulex. We provide one of the most extensive phylogenies of the evolution of α-CAs, with the inclusion of 261 amino acid sequences across taxa ranging from Cnidarians to Homo sapiens. While the phylogeny supports most of our previous understanding on the relationship of how α-CAs have evolved, we find that, contrary to expectations, amino acid conservation with bacterial α-CAs supports the supposition that extracellular α-CAs are the ancestral state of animal α-CAs. Furthermore, we show that two cytosolic and one GPI-anchored α-CA in Daphnia genus have homologs in sister taxa that are possible candidate genes to study for acid-base regulation. In addition, we provide further support for previous findings of a high rate of gene duplication within Daphnia genus, as compared with other organisms.