Sommer Aniela, Mahlknecht Georg, Obermeyer Gerhard
Molecular Plant Biophysics and Biotechnology, Centre of Biosciences and Health, Division of Allergy and Immunology, Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020 Salzburg, Austria.
J Membr Biol. 2007 Feb;215(2-3):111-23. doi: 10.1007/s00232-007-9011-6. Epub 2007 Jun 14.
Starting from the original theoretical descriptions of osmotically induced water volume flow in membrane systems, a convenient procedure to determine the osmotic water permeability coefficient (P (os)) and the relative nonosmotic volume (beta) of individual protoplasts is presented. Measurements performed on protoplasts prepared from pollen grains and pollen tubes of Lilium longiflorum cv. Thunb. and from mesophyll cells of Nicotiana tabacum L. and Arabidopsis thaliana revealed low values for the osmotic water permeability coefficient in the range 5-20 microm.s(-1) with significant differences in P (os), depending on whether beta is considered or not. The value of beta was determined using two different methods: by interpolation from Boyle-van't Hoff plots or by fitting a solution of the theoretical equation for water volume flow to the whole volume transients measured during osmotic swelling. The values determined with the second method were less affected by the heterogeneity of the protoplast samples and were around 30% of the respective isoosmotic protoplast volume. It is therefore important to consider nonosmotic volume in the calculation of P (os) as plant protoplasts behave as nonideal osmometers.
从膜系统中渗透诱导水体积流动的原始理论描述出发，本文提出了一种测定单个原生质体渗透水渗透系数（P(os)）和相对非渗透体积（β）的简便方法。对从麝香百合（Lilium longiflorum cv. Thunb.）的花粉粒和花粉管以及烟草（Nicotiana tabacum L.）和拟南芥（Arabidopsis thaliana）的叶肉细胞制备的原生质体进行的测量显示，渗透水渗透系数的值较低，在5 - 20微米·秒⁻¹范围内，根据是否考虑β，P(os)存在显著差异。β的值通过两种不同方法测定：从玻意耳 - 范特霍夫图进行插值，或通过将水体积流动的理论方程的解拟合到渗透肿胀期间测量的整个体积瞬变。用第二种方法测定的值受原生质体样品异质性的影响较小，约为相应等渗原生质体体积的30%。因此，在计算P(os)时考虑非渗透体积很重要，因为植物原生质体表现为非理想渗透计。
