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[1] [4] Once conditions become more favorable for growth, the akinete can then germinate back into a vegetative cell. [5] Increased light intensity, nutrients availability, oxygen availability, and changes in salinity are important triggers for germination. [5] In comparison to vegetative cells, akinetes are generally larger.
Once a heterocyst has formed it cannot revert to a vegetative cell. Certain heterocyst-forming bacteria can differentiate into spore-like cells called akinetes or motile cells called hormogonia, making them the most phenotypically versatile of all prokaryotes.
Over the winter Gloeotrichia forms dormant cells called akinetes that germinate and begin to form colonies when temperatures begin to increase. [7] As these cells grow, they uptake nutrients like P. However, they generally uptake more nutrients than they need and store it for later use for when they migrate to the nutrient deplete epilimnion.
In harsh conditions, A. circinalis form spore-like cells called akinetes. Akinetes are resistant to low temperature, desiccation , and darkness. Often, akinetes will hibernate in sediment until environmental conditions allow germination and re-growth.
Their cell size varies from less than 1 μm in diameter (picocyanobacteria) up to 100 μm (some tropical forms in the genus Oscillatoria) [39] [40] [41] Filamentous forms exhibit functional cell differentiation such as heterocysts (for nitrogen fixation), akinetes (resting stage cells), and hormogonia (reproductive, motile filaments). These ...
The fixed carbon and nitrogen sources are exchanged through channels between the cells in the filament. C. raciborskii does maintain photosystem I, allowing it to generate ATP by cyclic photophosphorylation. The mechanism of controlling this nitrogen fixation pathway is thought to involve the diffusion of an inhibitor of differentiation called ...
Nostoc with hormogonia. Hormogonia are motile filaments of cells formed by some cyanobacteria in the order Nostocales and Stigonematales.They are formed during vegetative reproduction in unicellular, filamentous cyanobacteria, and some may contain heterocysts and akinetes.
An akinete spore is large, non-motile, and thick walled, the wall of which is fused to that of the parent cell. Akinetes thick cell walls are enriched in food materials. Both aplanospores and akinetes are able to withstand unfavourable habitual conditions (cold, winter months or nutrient poor waters) and remain dormant under these conditions.