Cell Morphology of the Blue-Green Algae Under Culture Conditions fromCycas RevolutaIsolated. I: Light Microscope Observations

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Abstract
Colonies of blue-green algae isolated from root nodules of Cycas revoluta were grown on artificial media in order to study the effects of light (room conditions or continuous light) on culture morphogenesis. All the observations were carried out under the light microscope on fresh or stained material. Three main types of cells were observed: vegetative cells, heterocysts and akinetes. Colonies kept under room light grew more slowly, were darker green, had a larger number of vegetative cells in the youngest cultures and a larger number of akinetes in the older ones. The colony filaments presented a linear pattern. In the vegetative cells several granule types were recognizable, which, on the basis of the histochemical reactions used, could be identified respectively as polyphosphate, cyanophycin and lipidie granules. In the heterocysts and in the akinetes they were abundant. The colonies grown under continuous light conditions grew faster and their pigmentation was at first green, then yellow. In the older cultures the heterocysts and the akinetes were prevalent, while the colony filaments had a coiled pattern. In the vegetative cells the polyphosphate granules were largely represented while the cyanophycin granules were scarce. The results indicate that the blue-green algae also in culture has a variety of forms and structures and that this polymorphism seems to be related to environmental factors including light.