Palmucci Matteo, Ratti Simona, Giordano Mario
Laboratorio di Fisiologia delle Alghe, Dipartimento di Scienze del Mare, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
J Phycol. 2011 Apr;47(2):313-23. doi: 10.1111/j.1529-8817.2011.00963.x. Epub 2011 Mar 21.
An imbalance in the cellular C:N ratio may appreciably affect C allocation in algal cells. The consequences of these rearrangements of cellular pools on cell energetics, ecological fitness, and evolutionary trajectories are little known, although they are expected to be substantial. We investigated the fate of C in 11 microalgae cultured semicontinuously at three [NO3 (-) ] and constant pCO2 . We developed a new computational method for the semiquantitative use of Fourier transform infrared (FTIR) spectroscopy data for the determination of macromolecular composition. No obvious relationship was observed between the taxonomy and the allocation strategies adopted by the 11 species considered in this study. Not all species responded to a lower N availability by accumulating lipids or carbohydrates: Dunaliella parva W. Lerche and Thalassiosira pseudonana Hasle et Heimdal were homeostatic with respect to organic cell composition. A hyperbolic dependence of the lipid concentration from cell volume was observed. The level of reduction of organic constituents of green algae was parabolically related to size and was modulated in response to changes in N availability; the same was not true for the species bearing a "red" chloroplast. The above observations are discussed with respect to phytoplankton species composition and palatability for grazers, oleogenesis, and overall cell energetics.
细胞碳氮比失衡可能会显著影响藻类细胞中的碳分配。尽管预计细胞库这些重新排列对细胞能量学、生态适应性和进化轨迹的影响很大，但目前对此知之甚少。我们研究了在三种[NO3 (-) ]浓度和恒定pCO2条件下半连续培养的11种微藻中碳的去向。我们开发了一种新的计算方法，用于半定量利用傅里叶变换红外（FTIR）光谱数据来测定大分子组成。在本研究中考虑的11个物种的分类学与所采用的分配策略之间未观察到明显关系。并非所有物种都通过积累脂质或碳水化合物来应对较低的氮可用性：小杜氏藻（Dunaliella parva W. Lerche）和假微型海链藻（Thalassiosira pseudonana Hasle et Heimdal）在有机细胞组成方面保持稳态。观察到脂质浓度与细胞体积呈双曲线依赖关系。绿藻有机成分的还原水平与大小呈抛物线关系，并会根据氮可用性的变化进行调节；而具有“红色”叶绿体的物种则并非如此。我们针对浮游植物物种组成、食草动物的适口性、油脂生成和整体细胞能量学对上述观察结果进行了讨论。
