Fanesi Andrea, Raven John A, Giordano Mario
Laboratorio di Fisiologia delle Alghe e delle Piante, Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, via Brecce Bianche, 60131, Ancona, Italy.
Plant Cell Environ. 2014 Feb;37(2):512-9. doi: 10.1111/pce.12176. Epub 2013 Sep 9.
Acclimation to environmental changes involves a modification of the expressed proteome and metabolome. The reproductive advantage associated with the higher fitness that acclimation provides to the new conditions more than compensates for the costs of acclimation. To exploit such an advantage, however, the duration of the perturbation must be sufficiently long relative to the growth rate. Otherwise, a selective pressure may exist in favour of responses that minimize changes in carbon allocation and resource use and do not require reversal of the acclimation after the perturbation ceases (compositional homeostasis). We hypothesize that the choice between acclimation and homeostasis depends on the duration of the perturbation relative to the length of the cell cycle. To test this hypothesis, we cultured the green alga Tetraselmis suecica at two growth rates and subjected the cultures to three environmental perturbations. Carbon allocation was studied with Fourier transform infrared (FTIR) spectroscopy; elemental stoichiometry was investigated by total reflection X-ray fluorescence (TXRF) spectroscopy. Our data confirmed that growth rate is a crucial factor for C allocation in response to external changes, with a higher degree of compositional homeostasis in cells with lower growth rate.
对环境变化的适应涉及到所表达的蛋白质组和代谢组的改变。适应为新环境提供的更高适应性所带来的繁殖优势，足以弥补适应的成本。然而，要利用这种优势，相对于生长速率而言，扰动的持续时间必须足够长。否则，可能会存在一种选择压力，有利于那些将碳分配和资源利用的变化降至最低且在扰动停止后不需要逆转适应过程的反应（组成稳态）。我们假设，适应和稳态之间的选择取决于相对于细胞周期长度的扰动持续时间。为了验证这一假设，我们以两种生长速率培养绿藻瑞典四爿藻，并对培养物进行三种环境扰动。用傅里叶变换红外（FTIR）光谱研究碳分配；通过全反射X射线荧光（TXRF）光谱研究元素化学计量。我们的数据证实，生长速率是细胞响应外部变化时碳分配的关键因素，生长速率较低的细胞具有更高程度的组成稳态。
