Recent aspects of heterocyst biochemistry and differentiation

Among prokaryotes, cyanobacteria are the only clear-cut examples of intercellular compartmentation. Filamentous cyanobacteria can form the different cell types of vegetative cells, heterocysts and spore-forming akinetes. Heterocysts are often thought to be anaerobic compartments containing little else than nitrogenase. Experimental evidence of the past few years, however, indicates that the biochemistry of heterocysts is far more complex than believed hitherto. The process of the differentiation of vegetative cells to heterocysts is far more complex than believed hitherto. The process of the differentiation of vegetative cells to heterocysts is not fully understood at present, but aspects of this subject have become clear recently. As reviews on heterocyst biochemistry and differentiation are available (5,8,13,24,32,44,60,69), only some newer findings, not discussed extensively in the preceding publications, will be summarized here. (IFU)