Differential cellular response ofanabaena variabilisto iron

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Abstract
Anabaena variabilis is a photosynthetic, oxygenic bacterium which grows in multicellular filaments. We have observed two types of differential cell activities which occur in this organism with respect to iron nutrition. In iron limited cultures, a change in cellular organization is observed by light and electron microscopy. The change, characteristic of iron starvation is a breakdown of internal membranous cell structure and a thickened, electron dense outer boundary. With prolonged iron deprivation, cell lysis is observed and all cellular structure becomes disorganized. A second response to iron was noted in stationary phase cultures where a few cells in the filaments showed no cell disorganization. Autoradiography revealed that uptake of 55Fe was not uniform but only by a few cells in each filament.