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:purpose:The large-scale reproduction of Phaeocystis globosa has caused serious damage to the marine ecosystem in the coastal waters of China. The outbreak of algae blooms depends on the competitive advantage of their heteromorphic life history: colonial formation is beneficial to resist zooplankton predation, and the single isolated cells can absorb nutrients rapidly. methods:For RNA exaction, the biomass was resuspended in 2 mL RNA extraction buffer (1:1 mix of aqua-phenol and buffer L [0.5% SDS, 10 mM EDTA, 0.2 M sodium acetate (pH 5), and 1:100 β-mercaptoethanol)] and then incubated with DNase I (Takara, Japan) for 30 min at 37 °C to remove genomic DNA. RNA quality analysis, library construction, sequencing, data filtering and mapping were performed by the Novogene Bioinformatics Technology Co., Ltd. (Beijing, China). results:Three biological replicates from GX-C and ST-C were ensured statistical comparability and reliability of data. Raw data ranged from 25, 608,632 to 35,516,726 reads per sample. After producing more than 24 million clean reads, removing low-quality sequences and adapter sequences. Additionally, 4386 genes were differentially expressed at statistically significant levels, which included 2268 up-regulated genes and 2118 down-regulated genes. Genes with significant differential expression were involved in several pathways, including starch and sucrose, phagosome, inositol phosphate metabolism, fatty acid degradation. conclusions: In summary, we can find that colonial cells have stronger carbon fixation capacity. It is not used to synthesize fatty acids as reserves of energy, but to secrete EPS. The reduction of fatty acid makes P. globosa become “low-quality food” and the formation of colony from EPS reduces the chance of being ingestion by zooplankton.
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.