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.
Project description:Colon polyps represent precursor lesions of colon cancers and their malignant potential varies according to histological subtype. A rare subtype of colon polyps is the Peutz-Jeghers (PJ) polyp. PJ polyps mostly occur in the context of Peutz-Jeghers Syndrome which is characterized by the development of multiple polyps in the intestinal tract and hyperpigmentation of oral mucosa and lips. Peutz-Jeghers Syndrome is an autosomal dominant disorder caused by germline mutations of the Serine Threonin Kinase STK11 (LKB1). PJ polyps very rarely occur outside of Peutz-Jeghers Syndrome and are then referred to as solitary PJ polyps. Contrary to Peutz-Jeghers Syndrome, the genetic basis and the malignant potential of solitary PJ polyps is currently unknown. To date, only one study described a sporadic PJ polyp finding no mutations of STK11, indicating that the molecular profile of solitary PJ polyps differs from Peutz-Jeghers syndrome. Methylome analysis revealed global hypomethylation and CpG island hypermethylation, two features that have been described as hallmarks of the colorectal cancer epigenome. These results provide a paradigm for a premalignant lesion that is defined by epigenetic changes.