Silica Processing by Diatoms

本项目的总体目标是了解硅藻从其环境中摄取后的胞内状态和稳定化。初步工作一致地揭示了在硅沉积囊泡（SDV）内发生细胞壁形成之前，在细胞内部稳定存在大量的含硅物质/二氧化硅前体作为硅存储囊泡（SSP）。存在细胞内稳定机制的各种假设。因此，在第一个项目期间，我们将重点关注SSP的化学表征。我们将研究SSP如何依赖于生长条件和细胞周期。含SSP材料的提取和分级步骤将首先依赖于离心方法。此外，还设想使用硅钼酸测定和电感耦合等离子体发射光谱（ICP-OES）等技术来阐明SSP的Si含量。将通过29 Si NMR光谱和质谱（MS）对所获得的含Si样品进行进一步分析。假设由长链多胺（LCPAs）或LCPAs修饰的蛋白质稳定SSP，并将使用MS结合先进的固态NMR方法和光学光谱（IR/拉曼）进行测试。

The overarching goal of the present project is the understanding of the intracellular state and stabilization of silicic acid after its uptake by diatoms from their environment. Preliminary work consistently revealed the presence of significant amounts of silicon-bearing species/ silica precursors stabilized in the cell interior as Silicon Storage Pools (SSPs) before cell wall formation takes place inside the Silicon Deposition Vesicle (SDV). Various hypotheses for intracellular stabilization mechanisms exist. In the first project period, we will thus focus on the chemical characterization of SSPs. We will study how SSPs depend on growth conditions and on the cell cycle. The extraction and fractionation steps of SSP-containing material will first rely on centrifugation approaches. It is, furthermore, envisioned to elucidate the Si-content of SSPs using techniques like silicomolybdic acid assay and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The obtained Si-containing samples will be subject to further analysis by 29Si NMR spectroscopy and Mass Spectrometry (MS). The stabilization of SSPs by long-chain polyamines (LCPAs) or LCPA-modified proteins is hypothesized and will be tested using MS in combination with advanced solid-state NMR methods and optical spectroscopy (IR/Raman).