Name: Janet Rowe

Email: jrowe3@unl.edu

Author: Janet M. Rowe1, Marie-Francoise Fabre2, Daniel Gobena3, William H. Wilson4, and Steven W. Wilhelm5

Author affiliation: 1. Department of Biological Sciences, The University of Nebraska, Lincoln, NE 68582 2. Agrocampus Ouest, Rennes, France 35 042 3. Department of Genome Science and Technology, The University of Tennessee, Knoxville, TN 37996 4. Bigelow Laboratory for Ocean Science, West Boothbay Harbor, Maine 04575 5. Department of Microbiology, The University of Tennessee, Knoxville, TN 37996

Abstract title: Application of the Major Capsid Protein Gene as a Marker of Phylogenetic Diversity of Emiliania huxleyi Phycodnaviruses in the North Atlantic

Absstract:

Phycodnaviridae, aquatic viruses with 100-220 nm diameter capsids and ~100-560 kb genomes, may have significant global influence through top-down affects on their eukaryotic algal hosts. Though Phycodnaviridae identification and diversity has been traditionally based on and studied via the DNA polymerase gene, recent examinations have suggested that the Major Capsid Protein (MCP) gene may also serve as a reliable phylogenetic biomarker. In an examination of Emiliania huxleyi-infecting viruses (EhV) covering > 6,000 km of open ocean in the North Atlantic, we assessed the diversity of these Phycodnaviruses using MCP gene sequences. Nucleotide and amino acid sequences of the virus-size fraction of seawater were compared to lysates generated from exposure of host cultures to these same seawater, virus concentrates, as well as with those from known EhV isolates from coastal waters. While, overt spatial trends were not observed, phylogenetic analyses of nucleotide sequences revealed sequences in the offshore populations that are distinct from those of the coastal isolates. Observations that most sequences were sampled only once raise questions concerning the functional nature of particles associated with the unique sequences. Several other sequences were over-represented, suggesting a potential disproportional evenness that may be indicative of the importance of the associated particles within this ecosystem. Collectively, the data suggest a greater richness of EhV in the North Atlantic than previously understood from coastal isolates, and that there is likely greater diversity present than observed in this study. The data collected here present a unique opportunity to use phylogenetic data to select which cultured viruses may be of ecological significance, thereby warranting further study. Additionally, sequences from lysates can provide some answers as to the viability of those viruses detected from natural samples. Both of these aspects demonstrate the value of generating host-lysates from samples to run parallel analyses with natural samples. Overall, this investigation provides an assessment on the use of the MCP gene as a valuable biomarker of phylogenetic relationships as well as a wealth of new sequence data.