OSMOTIC-STRESS-INDUCED SYNTHESIS AND DEGRADATION OF INORGANIC POLYPHOSPHATES IN THE ALGA PHAEODACTYLUM-TRICORNUTUM

The potential role of inorganic polyphosphates in the response of alga l cells to osmotic stress was investigated. We show that changes in po lyphosphate metabolism of algae induced by osmotic stress can be easil y determined by measuring the metachromatic shift of toluidine blue pr oduced by polyphosphate and by analysing the size of the extracted pol yphosphate on urea/polyacrylamide gels. The amount and size of polypho sphate were found to differ considerably among different algal species . It is demonstrated that the alga Phaeodactylum tricornutum responds to hyperosmotic stress with a marked elongation of polyphosphate molec ules and a decrease in the total amount of extractable polyphosphate, while exposure to hypoosmotic stress results in an increase in soluble shorter-chain polyphosphates and a rise in total polyphosphate conten t.