Lemière Joël, Chang Fred
Department of Cell and Tissue Biology, University of San Francisco, CA, USA.
bioRxiv. 2023 Oct 2:2023.06.07.544129. doi: 10.1101/2023.06.07.544129.
Walled cells, such as plants, fungi, and bacteria cells, possess a high internal hydrostatic pressure, termed turgor pressure, that drives volume growth and contributes to cell shape determination. Rigorous measurement of turgor pressure, however, remains challenging, and reliable quantitative measurements, even in budding yeast are still lacking. Here, we present a simple and robust experimental approach to access turgor pressure in yeasts based upon the determination of isotonic concentration using protoplasts as osmometers. We propose three methods to identify the isotonic condition - 3D cell volume, cytoplasmic fluorophore intensity, and mobility of a cytGEMs nano-rheology probe - that all yield consistent values. Our results provide turgor pressure estimates of 1.0 ± 0.1 MPa for , 0.49 ± 0.01 MPa for , 0.5 ± 0.1 MPa for and 0.31 ± 0.03 MPa for . Large differences in turgor pressure and nano-rheology measurements between the strains demonstrate how fundamental biophysical parameters can vary even among wildtype strains of the same species. These side-by-side measurements of turgor pressure in multiple yeast species provide critical values for quantitative studies on cellular mechanics and comparative evolution.
有细胞壁的细胞，如植物、真菌和细菌细胞，具有较高的内部静水压力，称为膨压，它驱动体积增长并有助于细胞形状的确定。然而，精确测量膨压仍然具有挑战性，即使在芽殖酵母中，可靠的定量测量也仍然缺乏。在这里，我们提出了一种简单而稳健的实验方法，基于使用原生质体作为渗透压计来确定等渗浓度，从而获取酵母中的膨压。我们提出了三种确定等渗条件的方法——三维细胞体积、细胞质荧光团强度和细胞GEMs纳米流变探针的流动性——所有这些方法都能得出一致的值。我们的结果显示，[具体酵母种类1]的膨压估计值为1.0±0.1兆帕，[具体酵母种类2]为0.49±0.01兆帕，[具体酵母种类3]为0.5±0.1兆帕，[具体酵母种类4]为0.31±0.03兆帕。不同[酵母种类]菌株之间在膨压和纳米流变测量上的巨大差异表明，即使在同一物种的野生型菌株中，基本的生物物理参数也可能有所不同。对多种酵母物种的膨压进行的这些并行测量为细胞力学和比较进化的定量研究提供了关键数值。
