Anabaena sp. CA fails to synthesize heterocysts and nitrogenase when grown with KNO3 as the nitrogen source. By contrast, both heterocysts and proheterocysts are synthesized in NH4Cl-containing media to a level nearly commensurate with cells grown in the absence of combined nitrogen. The growth rate of the organism in NH4Cl-containing media was similar to that obtained with KNO3 as the nitrogen...

Heterocysts, formed when filamentous cyanobacteria, such as Anabaena sp. strain PCC 7120, are grown in the absence of combined nitrogen, are cells that are specialized in fixing atmospheric nitrogen (N(2)) under oxic conditions and that transfer fixed nitrogen to the vegetative cells of the filament. Anabaena sp. mutants whose sepJ gene (open reading frame alr2338 of the Anabaena sp. genome) wa...

Previous genomic analyses of the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 have identified three ferric uptake regulator (Fur) homologs with low sequence identities and probably different functions in the cell. FurA is a constitutive protein that shares the highest homology with Fur from heterotrophic bacteria and appears to be essential for in vitro growth. In this study...

Multiple molecular forms of glucose-6-phosphate dehydrogenase (G6PDH) were detected by activity staining in non-denaturing polyacrylamide gels of cell-free extracts from a range of cyanobacteria including Anabaena sp. PCC 7120, Synechococcus sp. PCC 7942, Plectonema boryanum PCC 73110, Synechocystis sp. PCC 6803, Nostoc sp. MAC PCC 8009 and the marine strain Synechococcus sp. WH7803. In most of...

The study was aimed to determine the chronic toxicity of Polynuclear aromatic hydrocarbon – Anthracene in response to pigments and metabolic study on three different cyanobacterial species such as Synechocystis sp., Anabaena fertilissima, and Nostoc muscorum. Test organisms were treated at different doses and encountered LC50/Mean Lethal Concentration (at which 50% lethality/ growth reduction o...

The polyphosphate glucokinases can phosphorylate glucose to glucose 6-phosphate using polyphosphate as the substrate. ORF all1371 encodes a putative polyphosphate glucokinase in the filamentous heterocyst-forming cyanobacterium Anabaena sp. PCC 7120. Here, ORF all1371 was heterologously expressed in Escherichia coli, and its purified product was characterized. Enzyme activity assays revealed th...

Nitrogen fixation and colonization by associative cyanobacteria in the aerial roots (pneumatophores) of black mangrove trees was evaluated in situ at Balandra lagoon, Baja California Sur, Mexico, for 18 consecutive months. Year-round vertical zonation of cyanobacterial colonization was determined along the pneumatophores. The bottom part close to the sediment was colonized mainly by nonheterocy...

We have quantitatively modeled heterocyst differentiation after fixed nitrogen step-down in the filamentous cyanobacterium Anabaena sp. PCC 7120 without lateral inhibition due to the patterning proteins PatS or HetN. We use cell growth and division together with fixed-nitrogen dynamics and allow heterocysts to differentiate upon the local exhaustion of available fixed nitrogen. Slow transport o...

Inactivation of sll0861 in Synechocystis sp. strain PCC 6803 or the homologous gene alr2432 in Anabaena sp. strain PCC 7120 had no effect on the growth of these organisms at a light intensity of 30 micromol photons m(-2) s(-1) but reduced their growth at a light intensity of 5 or 10 micromol photons m(-2) s(-1). In Anabaena, inactivation of the gene also significantly reduced the rate of hetero...

Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that fixes N(2) in specialized cells called heterocysts, which differentiate from vegetative cells in a process that requires the nitrogen control transcription factor NtcA. 2-Oxoglutarate-stimulated binding of purified NtcA to wild-type and modified versions of the ntcA gene promoter from Anabaena sp. was analyzed by mobility shift a...