ゲノム情報科学研究教育機構  アブストラクト
Date 2:00pm Jul 23, 2019
Speaker Dr. Nigel Grimsley
CNRS UMR 7232, BIOM, Avenue du Fontaulé, 66650 Banyuls-sur-Mer, France
Title Prasinovirus infection is firstly furtive, then furious, but phytoplankton fight
Abstract Prasinoviruses are large dsDNA viruses commonly found in aquatic systems worldwide, where they can infect and lyse unicellular prasinophyte algae such as Ostreococcus. In diurnal 12 h day ? 12 h dark cultures, transcriptome analyses revealed that prasinovirus gene expression was low in the day but much higher in the night, the majority of cells lysing the following morning. Host susceptibility is virus strain-specific, but resistance of susceptible Ostreococcus tauri strains to a virulent virus arises frequently. In clonal resistant lines that re-grew, viruses were usually present for many generations, and genes in a 150 kb-long chromosome 19 region were strongly over-expressed. Here, by serial dilutions of cultures at the time of inoculation, we estimated the frequency of resistant cells arising in virus-challenged O. tauri cultures to be 10E-3-10E-4 of the inoculated population. Regrowth of virus-resistant cells in O. tauri cultures that had been inoculated with OtV5 showed visible re-greening in less than 5 days, and by 8 days post-inoculation karyotypic changes in the host chromosome 19 were detectable. Virus adsorption to host cells was strain-specific and resistant cell lines showed a modified spectrum of host-virus specificities.
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