Quantitative Role of Glycine Betaine and DMSP in Cellular Nitrogen and Sulfur Budgets of Marine Phytoplankton

海洋浮游植物产生多种有机渗透物质 包括含氮化合物甘氨酸甜菜碱（GBT）， 其硫类似物二甲基磺基丙酸酯（DMSP）。 它 似乎GBT和DMSP使大，迄今为止， 对细胞氮的未被认识的贡献， 许多海洋浮游植物中的硫库， 颗粒有机氮（PON）和颗粒有机物 表层海水中的硫（POS）池。 之甚少 了解的生产，分配和循环 这些不稳定的生物化合物。信息从 文献和初步研究表明，许多 浮游植物既产生GBT又产生DMSP 同时，氮可利用性可能影响 GBT和DMSP的相对比例。 该项目将 进行实验室和实地研究，以测试以下各项 假设：1）GBT占显著（5-20%）比例 在某些海洋生物中， 浮游植物和DMSP是细胞的主要成分 2）分类学与GBT之间存在一定的关系 3）GBT和GMSP的水平， 浮游植物是氮可用性的函数， DMSP在氮限制下的优势; 4）浮游植物吸收 GBT和DMSP从他们的周围，并释放他们根据 5）在DMSP上生产GBT，或 选择产生GBT的物种， 高氮环境。 这项研究将提供新的和 关于甲基化的定量作用的重要数据 氮和硫向细胞氮渗透， 浮游植物的硫收支以及对PON和POS的影响 海 这些信息将有助于更好地了解 氮和硫的生物循环 海洋

Marine phytoplankton produce a variety of organic osmolytes including the nitrogenous compound glycine betaine (GBT) and its sulfur analog, dimethylsulfoniopropionate (DMSP). It appears that GBT and DMSP make large and hitherto unrecognized contributions to the cellular nitrogen and sulfur pools in many species of marine phytoplankton and to particulate organic nitrogen (PON) and particulate organic sulfur (POS) pools in surface sea water. Very little is known about the production, distribution and cycling of these labile biogenic compounds. Information from the literature and from preliminary studies suggests that many species of phytoplankton produce both GBT and DMSP simultaneously and that nitrogen availability may affect the relative proportions of GBT and DMSP. This project will conduct laboratory and field studies to test the following hypotheses: 1) GBT makes up a significant (5-20%) fraction of cellular nitrogen in certain species of marine phytoplankton and DMSP is a major constituent of cellular sulfur; 2) There is a relationship between taxonomy and GBT and DMSP production; 3) The levels of GBT and GMSP in phytoplankton are a function of nitrogen availability, with DMSP favored under N-limitation; 4) Phytoplankton take up GBT and DMSP from their surroundings and release them under certain conditions; 5) Production of GBT over DMSP, or selection of species which produce GBT, will be favored in high nitrogen environments. This study will provide new and important data on the quantitative role of methylated nitrogen and sulfur osmolytes to the cellular nitrogen and sulfur budgets of phytoplankton and to PON and POS in the sea. This information will lead to a better understanding of the biological cycling of nitrogen and sulfur in the ocean.