Physiological and ecological role of Dimethylsulfoniopropionate (DMSP) on psychrophilic phytoplankton

通过实验分析了嗜冷浮游植物生产二甲基磺酰丙酸（DMSP）的过程，探讨了其对浮游植物的生理生态作用。DMSP: ch1。a比值作为DMSP生产力对藻类生物量的指标。DMSP的产率具有物种特异性，即在冷条件下培养的一些嗜冷硅藻菌株在其细胞中产生DMSP，而一些不产生DMSP。一些产生DMSP的硅藻在其稳定生长阶段提高了DMSP的产量。硅藻的这种与生长相关的DMSP生产力可能导致在自然极地海洋下硅藻华后期观察到高浓度的DMSP，并可能影响它们的生存和物种演替。研究了水温、盐度等环境因素对浮游植物DMSP产量的影响。在实验室研究中，水温在1.7 ~ 5℃范围内对DMSP产能没有影响。硅藻菌株的DMSP产率在高盐度培养条件下趋于较高。特别是Haslea sp.和Navicula sp.在35.2高盐水环境下生长时，产生了大量的DMSP。它们被称为冰藻。虽然它们在盐水（高盐度）中生长时会产生大量的DMSP，但一旦它们从冰中出来进入融水（低盐度），它们就不会产生DMSP。DMSP在浮游植物中起着渗透剂的作用，但是，浮游植物在高盐度水域生长时会使用DMSP作为渗透剂，而在低盐度水域生长时会使用不同的化学物质来防止渗透冲击。

Dimethylsulfoniopropionate (DMSP) production by psychrophilic phytoplankton was experimentally analyzed in order to investigate its physiological and ecological role on phytoplankton. DMSP : chl.a ratios were calculated as indices of DMSP productivities against algal biomass. DMSP productivities were species-specific, i.e. some psychrophilic diatom strains cultured under cold conditions produced DMSP in their cells, and some of them did not produce DMSP. Some of DMSP producing diatoms increased their DMSP productivities during their stationary growth phase. This growth-related DMSP productivity by diatoms may result in the high concentrations of DMSP observed in the later stage of diatom blooms under natural polar seas, and may affect their survival and the succession of species. The environmental effects, such as water temperature and salinity, on phytoplankton DMSP productivities were also investigated. During a laboratory study, water temperature did not affect DMSP productivities in the range of 1.7-5℃. DMSP productivities of diatom strains were tend to be higher under high salinity culture conditions. Especially, Haslea sp. and Navicula sp. produced much DMSP when they grew under 35.2 high saline waters. They are known as icealgae. It is possible that although they produce much DMSP while they grow in the brine waters (high salinity), once they come out from the ice to the melt water (low salinity), they would not produce DMSP. DMSP functions as an osmolyte in phytoplankton, however, it is suggested that phytoplankton would use DMSP as an osmolyte when they grow higher salinity waters and they would use different chemicals to prevent from an osmotic shock when they grow lower salinity waters.