Determination of intracellular volume and internal solute concentrations of the green alga Chlorococcum submarinum

A method is described for measuring the cell volume of the unicellular green alga Chlorococcum submarinum, which depends on measurements of bromide concentration before and after disruption of the cells by ammonium hydroxide. Simultaneous equations are derived, which along with direct determination of cell water weight, allow the calculation of the intracellular volume in three different ways. The volumes calculated are in agreement indicating the validity of the method. The cell volumes and internal concentrations of glycerol, proline, potassium and sodium were determined for algae adapted to three salinities, 0.1, 0.5 and 1.0 M NaCl. The results showed that glycerol was the major internal solute and that the total measured solutes balanced the external osmotic pressure at all three salinities.Abbreviations DMSO dimethyl sulphoxide - Hepes N-2-hydroxyethyl]piperazine-N-2-ethane sulfonic acid - TCA trichloroacetic acid - Tris trishydroxymethyl]aminoethane