[Photodestruction of the blue-green alga Anabaena variablis]

The effect of light on the cells was studied with the obligate phototrophic blue-green alga Anabaena variabilis after its incubation in the dark. Incubation of the alga in the dark during two weeks was not essential for the cell reproduction systems in the light. Incubation in the dark during 3-4 weeks caused damages in the systems which were however reversible and repaired in the light. Longer incubation of the cells in the dark results in irreversible damages of the systems protecting them from photooxidation which may be the main factor preventing growth of the cells in the light.