Developmental regulation of methylammonium (ammonium) transport activity in the cyanobacterium Anabaena doliolum

Abstract Whiel heterocystous vegetative filaments of A. doliolum exhibited biphasic pattern of methylammonium (ammonium) uptake, its populations of akinetes deficient in chlorophylla, phycocyanin, oxygenic photosynthesis and aerobic nitrogenase activity showed monophasic uptake pattern with no evidence for second phase activity. Such akinetes with monophasic uptake pattern of methylammonium became biphasic by developing second phase activity at a stage during their germination at which oxygenic photosynthesis also developed. It is suggested that first phase activity of the methylammonium uptake process corresponds to plasma membrane regulated uptake activity leading to one methylammonium pool and that second phase activity of the metylammonium uptake process corresponds to the thylakoid membrane regulated uptake activity leading to the other methylammonium pool.