Silica Processing by Diatoms

本项目的首要目标是了解硅藻从环境中吸收硅酸后的细胞内状态和稳定性。初步研究一致表明，在硅沉积囊泡（SDV）内部形成细胞壁之前，在细胞内部作为硅存储池（ssp）稳定存在大量含硅物质/硅前体。关于细胞内稳定机制存在多种假设。因此，在第一个项目期间，我们将重点研究ssp的化学特性。我们将研究ssp如何依赖于生长条件和细胞周期。含ssp物质的提取和分馏步骤将首先依靠离心方法。此外，设想利用硅钼酸测定和电感耦合等离子体光学发射光谱（ICP-OES）等技术来阐明ssp的si含量。获得的含硅样品将通过29Si核磁共振光谱和质谱（MS）进行进一步分析。长链多胺（lcpa）或lcpa修饰的蛋白质对ssp的稳定性是假设的，并将使用MS结合先进的固态核磁共振方法和光谱学（IR/Raman）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).