The cyanobacteria Anabaena cylindrica and Synechococcus leopoliensis (= Anacystis nidulans) were grown at different levels of UV-B radiation (439, 717, 1230 and 1405 J m “2d_ l, weighted according Caldwell. 1971) for 2 days. Dry weight was hardly affected but phycocyanin content of both species decreased linearly to the level o f UV -B radiation.

The genes encoding the RNA subunit of ribonuclease P from the unicellular cyanobacterium Synechocystis sp. PCC 6803, and from the heterocyst-forming strains Anabaena sp. PCC 7120 and Calothrix sp. PCC 7601 were cloned using the homologous gene from Anacystis nidulans (Synechococcus sp. PCC 6301) as a probe. The genes and the flanking regions were sequenced. The genes from Anabaena and Calothrix...

Microorganisms in the rhizosphere mediate the cycling of nutrients, their enhanced mobilisation and facilitate their uptake, leading to increased root growth, biomass and yield of plants. We examined the promise of beneficial cyanobacteria and eubacteria as microbial inoculants, applied singly or in combination as consortia or biofilms, to improve growth and yields of okra. Interrelationships a...

HetR is a serine-type protease required for heterocyst differentiation in heterocystous cyanobacteria under conditions of nitrogen deprivation. We have identified the active Ser residue of HetR from Anabaena sp. strain PCC 7120 by site-specific mutagenesis. By changing the S152 residue to an Ala residue, the mutant protein cannot be labeled by Dansyl fluoride, a specific serine-type protein inh...

Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium that can use inorganic compounds such as nitrate or ammonium as nitrogen sources. In the absence of combined nitrogen, it can fix N2 in differentiated cells called heterocysts. Anabaena also shows substantial activities of amino acid uptake, and three ABC-type transporters for amino acids have been previously characterized. Seven new ...

In Anabaena 7120, heterocysts (cells specialized for nitrogen fixation) develop at the ends of filaments and at intervals within each filament. We have isolated a mutant Anabaena strain that develops heterocysts mostly at the ends of filaments. This mutant, PAT-1, grows poorly under nitrogen-fixing conditions. The wild-type gene that complements the mutation in PAT-1, called patA, was cloned an...

The expression of ferredoxin-NADP+ reductase (FNR) from Anabaena sp. PCC 7119 in heterocysts and vegetative cells has been quantified. Specific reductase activity in heterocysts was approximately 10 times higher than in vegetative cells, corresponding to the increased FNR protein content. This was confirmed by immunoquantification of the FNR protein from whole filaments of Anabaena sp. PCC 7120...

The movement protein (MP) of tobacco mosaic virus (TMV) facilitates the cell-to-cell spread of infection by altering the structure and function of plasmodesmata, the intercellular communication channels in plants. Because the protein was shown to interfere with intercellular communication when expressed in the cyanobacterium Anabaena sp. strain PCC 7120, whether the ability of the protein to ta...

The extent of biological CO2 fixation was evaluated for outdoor cultures of the cyanobacterium Anabaena sp. ATCC 33047. Culture conditions were optimized indoors in bubble-column photochemostats operating in continuous mode, subjected to irradiance cycles mimicking the light regime outdoors. Highest values achieved for CO2 fixation rate and biomass productivity were 1 and 0.6 g L(-1) day(-1), r...

Cyclic nucleotide PDEs (phosphodiesterases) regulate cellular levels of cAMP and cGMP by controlling the rate of degradation. Several mammalian PDE isoforms possess N-terminal GAF (found in cGMP PDEs, Anabaena adenylate cyclases and Escherichia coli FhlA; where FhlA is formate hydrogen lyase transcriptional activator) domains that bind cyclic nucleotides. Similarly, the CyaB1 and CyaB2 ACs (ade...