Department of Mathematics and Statistics, University of Strathclyde, Livingstone Tower, 26 Richmond St., Glasgow, Scotland, G1 1XH, UK.
Schiermeier Olentangy River Wetland Research Park, School of Environment and Natural Resources, The Ohio State University, Columbus, OH, 43202, USA.
ISME J. 2019 Nov;13(11):2834-2845. doi: 10.1038/s41396-019-0473-1. Epub 2019 Jul 26.
Phytoplankton face environmental nutrient variations that occur in the dynamic upper layers of the ocean. Phytoplankton cells are able to rapidly acclimate to nutrient fluctuations by adjusting their nutrient-uptake system and metabolism. Disentangling these acclimation responses is a critical step in bridging the gap between phytoplankton cellular physiology and community ecology. Here, we analyzed the dynamics of phosphate (P) uptake acclimation responses along different P temporal gradients by using batch cultures of the diatom Phaeodactylum tricornutum. We employed a multidisciplinary approach that combined nutrient-uptake bioassays, transcriptomic analysis, and mathematical models. Our results indicated that cells increase their maximum nutrient-uptake rate (V) both in response to P pulses and strong phosphorus limitation. The upregulation of three genes coding for different P transporters in cells experiencing low intracellular phosphorus levels supported some of the observed V variations. In addition, our mathematical model reproduced the empirical V patterns by including two types of P transporters upregulated at medium-high environmental and low intracellular phosphorus levels, respectively. Our results highlight the existence of a sequence of acclimation stages along the phosphate continuum that can be understood as a succession of acclimation responses. We provide a novel conceptual framework that can contribute to integrating and understanding the dynamics and wide diversity of acclimation responses developed by phytoplankton.
浮游植物面临着海洋上层动态环境中发生的营养物质变化。浮游植物细胞能够通过调整其营养吸收系统和新陈代谢，快速适应营养波动。解开这些适应反应是弥合浮游植物细胞生理学和群落生态学之间差距的关键步骤。在这里，我们通过使用菱形藻的分批培养物，分析了在不同磷时间梯度下磷吸收适应反应的动态。我们采用了一种多学科的方法，结合了营养吸收生物测定、转录组分析和数学模型。我们的结果表明，细胞既可以响应磷脉冲又可以响应强烈的磷限制来增加其最大养分吸收速率（V）。在细胞内磷水平较低的情况下，编码三种不同磷转运蛋白的基因上调，这支持了观察到的一些 V 变化。此外，我们的数学模型通过包括在中高环境磷水平和低细胞内磷水平下分别上调的两种类型的磷转运蛋白，再现了经验 V 模式。我们的结果强调了沿着磷酸盐连续体存在一系列适应阶段，可以将其理解为一系列适应反应的连续。我们提供了一个新的概念框架，可以有助于整合和理解浮游植物所开发的适应反应的动态和广泛多样性。
