Method |
The cytoplasmic, periplasmic, and total cell volumes were all derived from the distributions of solutes in cell suspensions, The rationale is illustrated in Fig. 1. Inulin, because it is large, cannot penetrate the outer membrane and is located only in the extracellular fluid. Sucrose, without the aid of a permease, cannot cross the plasma membrane and is located only in the periplasm and extracellular fluid. Water moves freely throughout the cell it is located in the cytoplasm, periplasm, and extracellular fluid. From Table V, the osmotic strength can be calculated as 270 mosM in Medium 63. The reciprocal of the graph in fig. 6 is Xcyto=0.36 mosmol/g dry weight of cells. The cells used in these experiments were grown in medium 63 in this case Vcell was 1.6 and Vcyto was 1.2 ml/g dry weight of cells. The intracellular osmotic strength was, therefore, 300 mosM (Xcyto/Vcyto) in agreement with the values obtained by the other methods. |