Diatoms are critical for regulating carbon and silicon cycles in the ocean. Several studies show that nitrogen enrichment can lead to diatom miniaturisation and increase silicification which are negative to carbon export in the ocean. Physiological and biochemical pathways linking nitrogen and silicification in diatoms remain unclear, however. Here, we propose a link between nitrogen, polyamines, and biogenic silica in the diatom Paralia sulcata. P. sulcata was evaluated as the experimental species in this study; it is a small and heavily silicified diatom that produces blooms in the North Sea and Yellow Sea after nitrogen enrichment. We examined the relationship of nitrogen concentration and source with polyamines overexpression. The response of polyamines, critical amino acids (aspartate, arginine, andornithine), and enzymes (arginine decarboxylase and ornithine decarboxylase) to four nitrogen conditions demonstrated that ammonia caninduce polyamines overexpression in the urea cycle. This increases long-chain polyamine synthesis, connecting to silane polypeptides to form Si-precipitating proteins, and promotes biogenic silica production. These findings are of great significance for understanding the coupling of nitrogen and silicon, and in particular the impact of diatom silicification on silicon cycling in the ocean.

Primary Presenter: Hao Zhou, East China Normal University (759094714@qq.com)

Authors:

Dongyan Liu,   ()

Donald Anderson,   ()