Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27514, USA.
Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA.
Environ Microbiol. 2018 Aug;20(8):3109-3126. doi: 10.1111/1462-2920.14386. Epub 2018 Sep 19.
Diatoms are a highly successful group of photosynthetic protists that often thrive under adverse environmental conditions. Members of the genus Pseudo-nitzschia are ecologically important diatoms which are able to subsist during periods of chronic iron limitation and form dense blooms following iron fertilization events. The cellular strategies within diatoms that orchestrate these physiological responses to variable iron concentrations remain largely uncharacterized. Using a combined transcriptomic and proteomic approach, we explore the exceptional ability of a diatom isolated from the iron-limited Northeast Pacific Ocean to reorganize its intracellular processes as a function of iron. We compared the molecular responses of Pseudo-nitzschia granii observed under iron-replete and iron-limited growth conditions to those of other model diatoms. Iron-coordinated molecular responses demonstrated some agreement between gene expression and protein abundance, including iron-starvation-induced-proteins, a putative iron transport system and components of photosynthesis and the Calvin cycle. Pseudo-nitzschia granii distinctly differentially expresses genes encoding proteins involved in iron-independent photosynthetic electron transport, urea acquisition and vitamin synthesis. We show that P. granii is unique among studied diatoms in its physiology stemming from distinct cellular responses, which may underlie its ability to subsist in low iron regions and rapidly bloom to outcompete other diatom taxa following iron enrichment.
硅藻是一组非常成功的光合原生生物，它们通常在不利的环境条件下茁壮成长。假壳属的成员是具有重要生态意义的硅藻，能够在慢性铁限制期间存活，并在铁施肥事件后形成密集的水华。硅藻中协调这些对可变铁浓度的生理反应的细胞策略在很大程度上仍未得到充分描述。我们采用了转录组学和蛋白质组学相结合的方法，研究了一种从铁限制的东北太平洋分离出来的硅藻适应铁浓度变化的特殊能力。我们比较了在铁充足和铁限制生长条件下观察到的假壳属 granii 的分子反应与其他模式硅藻的反应。铁协调的分子反应表明基因表达和蛋白质丰度之间存在一些一致性，包括铁饥饿诱导蛋白、一个假定的铁运输系统以及光合作用和卡尔文循环的组成部分。假壳属 granii 明显差异表达参与铁独立光合作用电子传递、尿素获取和维生素合成的蛋白质编码基因。我们表明，假壳属 granii 在生理学上与研究过的硅藻不同，这源于其独特的细胞反应，这可能是其在低铁区域生存并在铁富集后迅速繁殖以与其他硅藻竞争的能力的基础。
