Intracellular water exchange for measuring the dry mass, water mass and changes in chemical composition of living cells.
Intracellular water exchange for measuring the dry mass, water mass and changes in chemical composition of living cells.
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DOI：
10.1371/journal.pone.0067590
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Manalis SR
中科院分区：
文献类型：
--
作者：
Feijó Delgado F;Cermak N;Hecht VC;Son S;Li Y;Knudsen SM;Olcum S;Higgins JM;Chen J;Grover WH;Manalis SR
我们提出了一种对悬浮液中单个活细胞的干质量、干密度和水质量进行直接非光学定量的方法。通过依次测量基于 H2O 的流体和基于 D2O 的流体中细胞的浮力质量，可以同时获得干质量和干密度。细胞内 H2O 快速交换为 D2O，使细胞的含水量在两次测量中呈中性浮力，因此配对测量可单独得出细胞干燥材料的质量和密度。利用快速水交换的相同特性，我们还演示了细胞内水量的量化。在大肠杆菌群体中，我们将这些测量值配对来估计按质量和体积计算的干重百分比。然后我们关注细胞干密度——所有细胞生物分子的平均密度，按其相对丰度加权。鉴于不同生物分子类型（RNA、DNA、蛋白质）的密度各不相同，我们研究了是否可以检测细菌、真菌和哺乳动物细胞中生物分子组成的变化。在大肠杆菌和酿酒酵母中，干密度从稳定期增加到指数期，这与先前已知的核糖体生产上调导致的 RNA/蛋白质比率增加一致。对于哺乳动物细胞来说，生长条件的变化会导致干密度发生显着变化，表明细胞的蛋白质、核酸和脂质含量同时发生变化。
We present a method for direct non-optical quantification of dry mass, dry density and water mass of single living cells in suspension. Dry mass and dry density are obtained simultaneously by measuring a cell’s buoyant mass sequentially in an H2O-based fluid and a D2O-based fluid. Rapid exchange of intracellular H2O for D2O renders the cell’s water content neutrally buoyant in both measurements, and thus the paired measurements yield the mass and density of the cell’s dry material alone. Utilizing this same property of rapid water exchange, we also demonstrate the quantification of intracellular water mass. In a population of E. coli, we paired these measurements to estimate the percent dry weight by mass and volume. We then focused on cellular dry density – the average density of all cellular biomolecules, weighted by their relative abundances. Given that densities vary across biomolecule types (RNA, DNA, protein), we investigated whether we could detect changes in biomolecular composition in bacteria, fungi, and mammalian cells. In E. coli, and S. cerevisiae, dry density increases from stationary to exponential phase, consistent with previously known increases in the RNA/protein ratio from up-regulated ribosome production. For mammalian cells, changes in growth conditions cause substantial shifts in dry density, suggesting concurrent changes in the protein, nucleic acid and lipid content of the cell.
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影响因子：
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