南极微囊藻在南大洋形成大量的春季花朵,与高浓度的二甲基磺丙酸酯(DMSP)相吻合,二甲基亚砜(DMSO),二甲基硫醚(DMS),和丙烯酸酯。我们确定了这些化合物的浓度如何在暴露于光限制的南极黑曲霉培养物的生长过程中发生变化,次饱和,和饱和的PAR辐照度。每升细胞体积(CV)的细胞DMSP浓度范围为199至403mmol·LCV-1,在光限制PAR下观察到的最高浓度。细胞丙烯酸酯浓度没有随着辐照度水平或生长的变化而明显变化,范围在18至45mmol·LCV-1之间,构成约0.2%-2.8%的细胞碳。在每个细胞的基础上,溶解的丙烯酸酯和DMSO在指数生长期间随辐照度大幅增加,范围从0.91到3.15和0.24到1.39fmol·cell-1,分别,表明这些化合物大量出口到溶解相中。平均细胞DMSO:DMSP比率在分批生长的指数期和稳定期之间增加了7.6倍,细胞DMSO增加3至13倍,可能是由DMSP和DMS与活性氧(ROS)的非生物反应形成的。在mM水平,细胞DMSP和丙烯酸酯被认为是在南极洲不受氧化应激或ROS变化调节的事实上的抗氧化剂。相反,细胞DMSP浓度可能受其他生理过程控制,包括通过丙烯酸酯去除过量碳的溢流机制,DMS,和DMSO在由物理压力或营养限制引起的不平衡生长期间。一起,这些化合物应通过维持细胞功能和减少氧化应激来帮助南极疟原虫适应一系列PAR辐照度。
Phaeocystis antarctica forms extensive spring blooms in the Southern Ocean that coincide with high concentrations of dimethylsulfoniopropionate (DMSP), dimethylsulfoxide (DMSO), dimethylsulfide (DMS), and acrylate. We determined how concentrations of these compounds changed during the growth of axenic P. antarctica cultures exposed to light-limiting, sub-saturating, and saturating PAR irradiances. Cellular DMSP concentrations per liter cell volume (CV) ranged between 199 and 403 mmol · LCV -1 , with the highest concentrations observed under light-limiting PAR. Cellular acrylate concentrations did not change appreciably with a change in irradiance level or growth, ranging between 18 and 45 mmol · LCV -1 , constituting an estimated 0.2%-2.8% of cellular carbon. Both dissolved acrylate and DMSO increased substantially with irradiance during exponential growth on a per-cell basis, ranging from 0.91 to 3.15 and 0.24 to 1.39 fmol · cell-1 , respectively, indicating substantial export of these compounds into the dissolved phase. Average cellular DMSO:DMSP ratios increased 7.6-fold between exponential and stationary phases of batch growth, with a 3- to 13-fold increase in cellular DMSO likely formed from abiotic reactions of DMSP and DMS with reactive oxygen species (ROS). At mM levels, cellular DMSP and acrylate are proposed to serve as de facto antioxidants in P. antarctica not regulated by oxidative stress or changes in ROS. Instead, cellular DMSP concentrations are likely controlled by other physiological processes including an overflow mechanism to remove excess carbon via acrylate, DMS, and DMSO during times of unbalanced growth brought on by physical stress or nutrient limitation. Together, these compounds should aid P. antarctica in adapting to a range of PAR irradiances by maintaining cellular functions and reducing oxidative stress.