Pick U, Karni L, Avron M
Department of Biochemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
Plant Physiol. 1986 May;81(1):92-6. doi: 10.1104/pp.81.1.92.
A method to determine intracellular cation contents in Dunaliella by separation on cation-exchange minicolumns is described. The separation efficiency of cells from extracellular cations is over 99.9%; the procedure causes no apparent perturbation to the cells and can be applied to measure both fluxes and internal content of any desired cation. Using this technique it is demonstrated that the intracellular averaged Na(+), K(+), and Ca(2+) concentrations in Dunaliella salina cultured at 1 to 4 molar NaCl, 5 millimolar K(+), and 0.3 millimolar Ca(2+) are 20 to 100 millimolar, 150 to 250 millimolar, and 1 to 3 millimolar, respectively. The intracellular K(+) concentration is maintained constant over a wide range of media K(+) concentrations (0.5-10 millimolar), leading to a ratio of K(+) in the cells to K(+) in the medium of 10 to 1,000. Severe limitation of external K(+), induces loss of K(+) and increase in Na(+) inside the cells. The results suggest that Dunaliella cells possess efficient mechanisms to eliminate Na(+) and accumulate K(+) and that intracellular Na(+) and K(+) concentrations are carefully regulated. The contribution of the intracellular Na(+) and K(+) salts to the total osmotic pressure of cells grown at 1 to 4 molar NaCl, is 5 to 20%.
本文描述了一种通过阳离子交换微型柱分离来测定杜氏藻细胞内阳离子含量的方法。细胞与细胞外阳离子的分离效率超过99.9%；该方法对细胞无明显干扰，可用于测量任何所需阳离子的通量和细胞内含量。使用该技术表明，在1至4摩尔氯化钠、5毫摩尔钾离子和0.3毫摩尔钙离子条件下培养的盐生杜氏藻细胞内平均钠离子、钾离子和钙离子浓度分别为20至100毫摩尔、150至250毫摩尔和1至3毫摩尔。在较宽的培养基钾离子浓度范围（0.5 - 10毫摩尔）内，细胞内钾离子浓度保持恒定，导致细胞内钾离子与培养基中钾离子的比例为10至1000。外部钾离子的严重限制会导致细胞内钾离子流失和钠离子增加。结果表明，杜氏藻细胞具有有效的机制来消除钠离子并积累钾离子，并且细胞内钠离子和钾离子浓度受到严格调节。在1至4摩尔氯化钠条件下生长的细胞中，细胞内钠盐和钾盐对总渗透压的贡献为5%至20%。
