Project description:Virophages are small dsDNA viruses dependent on a nucleocytoplasmic large-DNA virus infection of a cellular host for replication. Putative virophages infecting algal hosts are classified together with Polinton-like viruses, transposable elements widely found in algal genomes, yet the lack of isolated strains raises questions about their existence as independent entities. We isolated and characterized a virophage (PgVV-14T) co-infecting Phaeocystis globosa with the Phaeocystis globosa virus-14T (PgV-14T).
Project description:Phaeocystis is a globally distributed Prymnesiophyceae genus and usually forms massive harmful colony blooms, which impact marine ecosystem, mariculture, human health, and even threaten coastal nuclear power plant safety. However, the mechanisms behind the colony formation from the solitary cells remain poorly understood. Here, we investigated metabolic processes of both solitary and non-flagellated colonial cells of Phaeocystis globosa at different colonial bloom stages using a metaproteomic approach. Temperature was significantly correlated with Phaeocystis colony bloom formation, and the flagellated motile solitary cells with abundant flagellum-associated proteins, such as tubulin and dynein, were the exclusive cellular morphotype at the solitary cell stage featured with temperatures ≥ 21℃. When the temperature decreased to <21℃, tiny colonies appeared and the flagellum-associated proteins were identified lower abundances in both solitary and non-flagellated colonial cells, while proteins involved in biosynthesis, chain polymerization and aggregation of glycosaminoglycan (GAG), a key constituent of gelatinous matrix, were identified higher abundances, indicating the central role of active GAG biosynthesis during the colony formation. Furthermore, light utilization, carbon fixation, nitrogen assimilation, and amino acid and protein synthesis were also enhanced to provide sufficient energy and substrates for GAG biosynthesis. This study highlighted that temperature induced re-allocation of energy and substances toward GAG biosynthesis is essential for colony bloom formation of P. globosa.
