Chronological distribution of dinoflagellate-infecting RNA virus in marine sediment core.

Affiliation

Takahashi M(1), Wada K(2), Takano Y(1), Matsuno K(3), Masuda Y(4), Arai K(5), Murayama M(6), Tomaru Y(7), Tanaka K(8), Nagasaki K(9).
Author information:
(1)Faculty of Science and Technology, Kochi University, Nankoku 783-8502, Kochi, Japan.
(2)Department of Medical Sciences, University of Miyazaki, Miyazaki 889-1692, Japan.
(3)Japan Software Management, Yokohama 221-0056, Kanagawa, Japan.
(4)Faculty of Agriculture and Marine Science, Kochi University, Nankoku 783-8502, Kochi, Japan.
(5)Center for Advanced Marine Core Research, Kochi University, Nankoku 783-8502, Kochi, Japan.
(6)Faculty of Agriculture and Marine Science, Kochi University, Nankoku 783-8502, Kochi, Japan; Center for Advanced Marine Core Research, Kochi University, Nankoku 783-8502, Kochi, Japan.
(7)Fisheries Technology Institute, Japan Fisheries Research and Education Agency, Hatsukaichi 739-0452, Hiroshima, Japan.
(8)Usa Marine Biological Institute, Kochi University, Usa 781-1164, Kochi, Japan.
(9)Faculty of Science and Technology, Kochi University, Nankoku 783-8502, Kochi, Japan; Faculty of Agriculture and Marine Science, Kochi University, Nankoku 783-8502, Kochi, Japan; Center for Advanced Marine Core Research, Kochi University, Nankoku 783-8502, Kochi, Japan. Electronic address: [Email]

Abstract

A bivalve-killing marine dinoflagellate, Heterocapsa circularisquama, is susceptible to the infectious single-stranded RNA virus, Heterocapsa circularisquama RNA virus (HcRNAV). The ecological relationship between H. circularisquama and HcRNAV was intensively studied from 2001 through 2005; however, only limited data are available for the ecological dynamics of HcRNAV before 2001. In this study, we applied radiometric dating and reverse transcription PCR (RT-PCR) to determine the chronological distribution of HcRNAV in a marine sediment core sampled from the Uranouchi Inlet, Kochi, Japan, where H. circularisquama was first discovered. Our results show that HcRNAV had existed in the inlet long before its first bloom in 1988. Furthermore, five HcRNAV variants, phylogenetically distinguishable based on the nucleotide sequence of the major capsid protein (MCP) gene, were identified. These variants were found to be distributed throughout the core over time, suggesting that the HcRNAV sequences registered in the NCBI database are only a portion of the variants that have emerged in the history of HcRNAV diversification. Herein, we have verified the applicability of the retrospective approach for speculating the distribution of algal RNA viruses over time in aquatic environments.