Springer Online Journal Archives 1860-2000
Abstract Nitrogen starvation, effected by incubating a culture ofAnabaena cylindrica in a medium free from combined nitrogen and under an atmosphere of 1% CO2 in argon, leads to rapid and characteristic changes in the appearance, structure and function of the alga. Change of colour, due apparently to a decrease in the amounts of nitrogenous pigments, is accompanied by a structural transformation of vegetative cells: cyanophycin granules and polyhedral bodies disintegrate, lipid and glycogen accumulate, and large membrane-bound spaces form by means of thylakoid swelling and vesiculation. The rate of heterocyst differentiation and nitrogenase activity is increased. These changes are fully reversed on addition of ammonia to the culture. It appears that thylakoids reform by coalescence of small vesicles assembled in the intrathylakoidal space. Rapid ammonia assimilation is indicated by ample formation of cyanophycin granules in vegetative cells and of “plugs” in the heterocysts.
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