Apparent free space and cell volume estimation: A non-destructive method for assessing the growth and membrane integrity/viability of immobilised plant cells.

Pre-existing methods for measuring cell or organelle volume based on the selective permeability of biological membranes have been modified to make them suitable for determining the intracellular volume of immoblised cells. When a freely permeable substance (e.g. tritiated water) and an impermeable substance ((14)C labelled mannitol is often suitable) are mixed with an immobilised cell culture, the two substances are diluted to different degrees. The extent of the difference allows the total intracellular volume of intact cells to be calculated. This volume is shown to be a useful parameter for assessing cell growth. The application of the method to follow membrane integrity and cell viability is also discussed.