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At least 19 recordsLinked to original sources

PubMed1998

Nitrogen control of the glnN gene that codes for GS type III, the only glutamine synthetase in the cyanobacterium Pseudanabaena sp. PCC 6903.

Pseudanabaena sp. strain PCC 6903 is the first cyanobacteria lacking the typical prokaryotic glutamine synthetase type I encoded by the glnA gene. The glnN gene product, glutamine synthetase type III, is the only glutamine synthetase activity present in this cyanobacterium. Analysis of glnN expression clearly indicated a nitrogen-dependent regulation. Pseudanabaena glnN gene expression and GSIII activity were upregulated under nitrogen starvation or using nitrate as a nitrogen source, while low levels of transcript and activity were found in ammonium-containing medium. Primer extension analysis showed that the glnN gene promoter structure resembled that of the NtcA-related promoters. Mobility shift assays demonstrated that Synechocystis sp. PCC 6803 NtcA protein, expressed and purified from Escherichia coli, bound to the promoter of the Pseudanabaena 6903 glnN gene. The NtcA control of the glnN gene in this cyanobacterium suggested that, in the absence of a glnA gene, NtcA took control of the only glutamine synthetase gene in a fashion similar to the way the glnA gene is governed in those cyanobacteria harbouring a glnA gene.

Amino Acid Sequence↗

PubMed2001

Bioactive compounds from Pseudanabaena species (Cyanobacteria).

Bioactive products of the multicellular filamentous benthic cyanobacterium, Pseudanabaena species, isolated from wastewater stabilization ponds at Marrakech, were tested against some pathogenic micro-organisms. Extracellular and intracellular products released by this blue-green alga in the stationary, growth phase, reduced the survival of Escherichia coli, Salmonella sp., Staphylococcus aureus and Candida albicans, and stimulated the growth of non-O1 V. cholerae, whereas no significant effect was noted on the growth of Candida tropicalis. Intracellular substances (methanolic extract) had a stronger inhibitory effect on these micro-organisms than that produced by extracellular substances. These antibacterial and antifungal substances may have a pharmacological value. They may have an important ecological effect on the composition of the bacterial community in Marrakech stabilization ponds when blooms of Pseudanabaena species occurred in this sewage treatment ecosystem during hot periods.

Bacteria↗

PubMed1978

On the linkages between chromophore and protein in biliproteins, VII. Amino acid sequence in the chromophore regions of C-phycoerythrin from Pseudanabaena W 1173 and Phormidium persicinum.

Bilipeptides from all chromophore regions were prepared by trypsin digestion of C-phycoerythrin from Pseudanabaena W 1173 and Phormidium persicinum. Analytical separation and quantitative determination of bilipeptides was achieved by isoelectric focusing, preparative isolation by gel chromatography and ion-exchange chromatography. Amino acid analysis revealed cysteine as the only amino acid common to all chromopeptides. Amino acid sequences were determined by Edman degradation and the dansyl-Edman technique. Sequences are different in all 5 and 6 chromophore regions, respectively. Possible homologies are discussed. A thioether linkage between ring A of the chromophore and cysteine was found in the bilipeptides (as before in biliproteins). A second linkage (serine ester) was found in only one peptide (CM 4.I from Pseudanabaena W 1173). This peptide absorbs as cation at a longer wavelength (559 nm) than the other bilipeptides (542 - 550 nm).

Amino Acid Sequence↗

PubMed1991

Gas vesicle synthesis in the cyanobacterium Pseudanabaena sp.: occurrence of a single photoregulated gene.

Gas vesicles are subcellular inclusions found in a large number of aquatic prokaryotes. The gvpA gene, which frequently occurs as a multigene family, encodes the major gas vesicle structural protein. In several cyanobacteria, another gene, gvpC, encodes a different protein which might be a dispensable element for gas vesicle formation. We report here the molecular characterization of a gvpA gene in Pseudanabaena sp. PCC 6901. In this planktonic cyanobacterium, it is the only gvp gene which could be detected, and electrophoretic analysis of isolated gas vesicles revealed the presence of a single protein. A monocistronic mRNA species corresponds to the transcription of the gvpA gene and the abundance of the gvpA mRNA is inversely correlated with photosynthetic photon flux indicating that a light-dependent transcriptional regulation is likely to be involved in the control of gas vacuolation in this strain.

Amino Acid Sequence↗

PubMed1991

Molecular cloning and transcriptional analysis of the cpeBA operon of the cyanobacterium Pseudanabaena species PCC7409.

The cpeBA operon of the Group III chromatically adapting cyanobacterium Pseudanabaena species PCC 7409 was cloned, sequenced and characterized. The cpeBA genes are transcribed in green-light-grown cells as an abundant 1400-nucleotide mRNA which initiates 69 nucleotides upstream from the cpeB translation start. Extensive sequence identity, extending 70 nucleotides 5' to the transcription start, occurs among cpeBA promoters of Group II and III chromatic adapters. Cell extracts of green-light-grown Calothrix species PCC 7601 contain an activity which specifically binds a restriction fragment containing the Pseudanabanea species PCC 7409 cpeBA promoter. Green-light-dependent cpeBA transcription in Group II and III chromatically adapting cyanobacteria is suggested to be similarly controlled by a transcriptional activator.

Amino Acid Sequence↗

PubMed1981

Effects of chromatic illumination on cyanobacterial phycobilisomes. Evidence for the specific induction of a second pair of phycocyanin subunits in Pseudanabaena 7409 grown in red light.

Pseudanabaena 7409 is a chromatically cyanobacterium which photocontrols the synthesis of both phycoerythrin and phycocyanin [Tandeau de Marsac (1977) J. Bacteriol. 130, 82--91]. Phycobilisomes, isolated from cells grown in either green or red light, have been dissociated and the component biliproteins purified and characterized. Phycobilisomes isolated from cells grown in green light were composed of allophycocyanin B, allophycocyanin, two phycocyanin subunits (one alpha-type and one beta-type subunit), phycoerythrin and eight uncolored polypeptides. When dissociated phycobilisomes were chromatographed on DEAE-cellulose at pH 5.5, most of the phycocyanin was recovered as part of a large (17.3 S) multiprotein complex with phycoerythrin (molar ratio 1 : 1). This complex also contained five of the uncolored polypeptides found in intact phycobilisomes isolated from cells grown in green light. Phycobilisomes isolated from cells grown in red light were composed of allophycocyanin B, allophycocyanin, four phycocyanin subunits (two alpha-type and two beta-type subunits), and six uncolored polypeptides. When these phycobilisomes were dissociated, the phycocyanin was recovered as a large (21.0 S) multiprotein complex which was composed of the four phycocyanin subunits types and four uncolored polypeptides. This complex was morphologically identical to the rod-like stacks of discs about 6 x 12 nm which form the peripheral rods of intact phycobilisomes. Each of the four phycocyanin subunits found in the complex isolated from the phycobilisomes of cells grown in red light was purified to homogeneity and characterized. Amino acid compositions of the four subunits indicated that each subunit was a unique gene product. Two of the subunits of the complex were apparently identical to those of the phycocyanin purified from phycobilisomes isolated from cells grown in green light. These studies suggest that one pair of phycocyanin subunits was synthesized constitutively (i.e. irrespective of the light wavelength to which the cells were exposed during growth) while the synthesis of the second pair of phycocyanin subunits was specifically induced during growth in red light.

Amino Acids↗

PubMed2001

The gas vesicle gene (gvp) cluster of the cyanobacterium Pseudanabaena sp. strain PCC 6901.

A gene cluster located downstream from gvpA in the cyanobacterium Pseudanabaena sp. strain PCC 6901 has been cloned and sequenced. The three genes, orf1, gvpN and gvpJ, are consecutive with no intergenic region. In contrast to GvpN and GvpJ, which share high similarity at the amino acid level with their counterparts in other cyanobacteria and halophilic archaea, Orf1 is only 29% identical to the C-terminal part of GvpC from Anabaena flos-aquae and its sequence organization is reminiscent of the halophilic archaeal GvpC.

Amino Acid Sequence↗

PubMed1992

Conjugative gene transfer in marine cyanobacteria: Synechococcus sp., Synechocystis sp. and Pseudanabaena sp.

Versatility of gene transfer by transconjugation in marine cyanobacteria was demonstrated. In this study, seven different marine cyanobacteria were used as recipient cells. First, transconjugation was carried out using the mobilizable transposon (Tn5) carrying plasmid pSUP1021. Transconjugates were observed in all marine cyanobacteria tested. Second, the broad-host-range vector pKT0230 (IncQ) was tested for transconjugation. pKT230 has been successfully transferred in a marine cyanobacterium Synechococcus sp. NKBG15041C, and replicated as an autonomous replicon without alteration in the restriction enzyme pattern. A maximum transfer efficiency of 5.2 x 10(-4) transconjugants/recipient cell was observed, when mating was performed on agar plates containing low salinity (0.015 M NaCl) medium. This is the first study to demonstrate gene transfer in marine cyanobacteria via transconjugation.

Biotechnology↗

PubMed2026

Nitrogen sources and concentrations shape algal odor compounds: Key drivers of β-cyclocitral and β-ionone in water bodies of the lower Yangtze River.

Taste and odor (T&O) compounds derived from cyanobacterial blooms pose escalating threats to freshwater security worldwide, yet the drivers of specific T&O metabolites remain poorly constrained. Here, we investigated the dual effects of nitrogen (N) sources and concentrations on the production of β-cyclocitral and β-ionone, two algal-derived T&O compounds, through integrated field surveys (54 sites across lakes and rivers) in the eutrophic lower Yangtze River, China, and laboratory cultivation of typical cyanobacteria (Microcystis aeruginosa and Pseudanabaena cinerea). Our field data revealed that the concentrations of β-cyclocitral and β-ionone in lakes and rivers were not significantly different, but increased with the trophic level index. Redundancy analysis and Mantel analysis showed that Microcystis and Pseudanabaena were potentially dominant contributors to β-cyclocitral and β-ionone in the water column. Structural equation modeling and variation partitioning analysis showed that enhanced nitrate (NO3--N) significantly promoted the production of these compounds. Laboratory experiments demonstrated that inorganic N (NaNO₃) maximized total T&O yields by promoting algal biomass, whereas organic N (urea and glutamic acid) elevated the T&O production per unit biomass by 1.5- to 9.5-fold. Notably, Pseudanabaena exhibited a 2.3-fold higher β-ionone yield than Microcystis, with greater sensitivity to N concentrations. Our study highlights the critical role of nitrogen pollution, both source and concentration, in the production of T&O compounds by phytoplankton and provides reference data for managing T&O issues in rivers and shallow lakes.

Norisoprenoids↗

PubMed2001

Effects of the organophosphorus insecticide fenitrothion on growth in five freshwater species of phytoplankton.

The acute toxicity of the insecticide fenitrothion was measured using four freshwater algae (Chlorella saccharophila, Chlorella vulgaris, Scenedesmus acutus, and Scenedesmus subspicatus) and one cyanobacteria (Pseudanabaena galeata). Insecticide concentrations eliciting 50% growth reduction over 96 hr (EC50) ranged from 0.84 to 11.9 mg/L. Fenitrothion was more toxic than other pesticides studied with the same algal species such as chlorsulfuron, molinate, and pyridaphenthion. The transformation of effective concentrations of fenitrothion and other pesticides obtained from toxicity measurements into percent of the saturation level in water is used as a first evaluation of potential hazard to aquatic systems. The insecticides fenitrothion and pyridaphenthion were less hazardous than the herbicides atrazine, benthiocarb, cinosulfuron, chlorsulfuron, methyl-bensulfuron, and molinate. The two species of Chlorella and the cyanobacterium Pseudanabaena were more tolerant to fenitrothion than the two species of Scenedesmus.

Dose-Response Relationship, Drug↗

PubMed1997

Amino acid transport in taxonomically diverse cyanobacteria and identification of two genes encoding elements of a neutral amino acid permease putatively involved in recapture of leaked hydrophobic amino acids.

The activities of uptake of thirteen 14C-labeled amino acids were determined in nine cyanobacteria, including the unicellular strains Synechococcus sp. strain PCC 7942 and Synechocystis sp. strain PCC 6803; the filamentous strain Pseudanabaena sp. strain PCC 6903, and the filamentous, heterocyst-forming strains Anabaena sp. strains PCC 7120 and PCC 7937; Nostoc sp. strains PCC 7413 and PCC 7107; Calothrix sp. strain PCC 7601 (which is a mutant unable to develop heterocysts); and Fischerella muscicola UTEX 1829. Amino acid transport mutants, selected as mutants resistant to some amino acid analogs, were isolated from the Anabaena, Nostoc, Calothrix, and Pseudanabaena strains. All of the tested cyanobacteria bear at least a neutral amino acid transport system, and some strains also bear transport systems specific for basic or acidic amino acids. Two genes, natA and natB, encoding elements (conserved component, NatA, and periplasmic binding protein, NatB) of an ABC-type permease for neutral amino acids were identified by insertional mutagenesis of strain PCC 6803 open reading frames from the recently published genomic DNA sequence of this cyanobacterium. DNA sequences homologous to natA and natB from strain PCC 6803 were detected by hybridization in eight cyanobacterial strains tested. Mutants unable to transport neutral amino acids, including natA and natB insertional mutants, accumulated in the extracellular medium a set of amino acids that always included Ala, Val, Phe, Ile, and Leu. A general role for a cyanobacterial neutral amino acid permease in recapture of hydrophobic amino acids leaked from the cells is suggested.

Amino Acid Transport Systems, Neutral↗

PubMed2002

Detection and quantification of microcystins from cyanobacteria strains isolated from reservoirs and ponds in Morocco.

In Morocco, the occurrence of toxic cyanobacteria blooms is confirmed in some water bodies used for recreational and/or as drinking water reservoirs. According to WHO recommendations, the establishment of a monitoring program for microcystins is a necessity. This paper presents toxicological studies of 19 toxic cyanobacteria strains of Microcystis, Synechocystis, Pseudanabaena, and Oscillatoria. These strains were isolated from various water bodies including natural lakes, reservoirs, and ponds located in central regions of Morocco. The isolation, culture, and biomass production of these strains was made on Z8 or BG13 media under laboratory controlled conditions. The hepatotoxicity of cyanobacterial lyophilized material was confirmed by mouse bioassays. The amount of microcystins produced by each strain was determined by the enzyme-linked immunosorbent assay (ELISA). The detection and identification of microcystin variants was performed by high performance liquid chromatography (HPLC) with photodiode array detection. Almost all strains showed medium to high toxicity, the estimated LD50 i.p. mice bioassay ranged between 28 to 350 mg/kg body weight. The concentrations of microcystins varied between 2.16 to 944 micrograms/g and 26.8 to 1884 micrograms/g dry weight determined by ELISA and HPLC, respectively. The screening of bloom-forming and microcystin producer cyanobacteria strains in these fresh water bodies leads us to propose the need for the establishment of a survey of cyanobacteria and a cyanotoxin-monitoring program.

Animals↗

PubMed2005

Limnothrix redekei (Van Goor) Meffert (Cyanobacteria) strains from Lake Kastoria, Greece form a separate phylogenetic group.

Three strains of Limnothrix (Cyanobacteria) isolated from Lake Kastoria, Greece, were characterized based on their morphological features and 16S rRNA gene sequences. The Limnothrix isolates 007a, 165a, and 165c can morphologically be assigned to Limnothrix redekei (Van Goor) Meffert. The 16S rRNA gene of the Limnothrix strains showed a 99% similarity to the 16S rRNA gene of Planktothrix sp. FP1. Limnothrix redekei strains 165a, 165c, 007a and Planktothrix sp. FP1 formed a separate cluster in the cyanobacterial 16S rRNA gene tree. It was distinct from the Pseudanabaena cluster, which included the other Limnothrix strains isolated from northern temperate lakes. This is the first report on the phylogeny of L. redekei strains originating from a Mediterranean lake (southern Europe) and provides new data about the genus Limnothrix.

Analysis of Variance↗

PubMed2005

Cyanobacteria and prawn farming in northern New South Wales, Australia--a case study on cyanobacteria diversity and hepatotoxin bioaccumulation.

Harmful cyanobacteria pose a hazard to aquatic ecosystems due to toxins (hepatotoxic microcystins, nodularins, and cylindrospermopsin) they produce. The microcystins and nodularins are potent toxins, which are also tumor promoters. The microcystins and nodularins may accumulate into aquatic organisms and be transferred to higher trophic levels, and eventually affect vector animals and consumers. Prawn farming is a rapidly growing industry in Australia. Because information regarding effects of cyanobacteria at prawn farms was lacking, we examined diversity of cyanobacteria and toxin production plus bioaccumulation into black tiger prawns (Penaeus monodon) under both field (northern New South Wales, Australia, December 2001-April 2002) and laboratory conditions. Samples were analyzed for hepatotoxins using enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). The maximum density of cyanobacteria (1 x 10(6) to 4 x 10(6) cells/l) was reached in April. Cyanobacteria encountered were Oscillatoria sp. (up to 4 x 10(6) cells/l), Pseudanabaena sp. (up to 1.8 x 10(6) cells/l), Microcystis sp. (up to 3.5 x 10(4) cells/l), and Aphanocapsa sp. (up to 2 x 10(4) cells/l). An uncommon cyanobacterium, Romeria sp. (up to 2.2 x 10(6) cells/l), was also observed. Contrasting earlier indications, toxic Nodularia spumigena was absent. Despite that both Oscillatoria sp. and Microcystis sp. are potentially hepatotoxic, hepatotoxin levels in phytoplankton samples remained low (up to 0.5-1.2 mg/kg dw; ELISA) in 2001-2002. ELISA was found suitable not only for phytoplankton but prawn tissues as well. Enzymatic pretreatment improved extractability of hepatotoxin from cyanobacteria (nodularin from N. spumigena as an example), but did not generally increase toxin recovery from prawn hepatopancreas. There were slightly increasing hepatotoxin concentrations in prawn hepatopancreas (from 6-20 to 20-80 microg/kg dw; ELISA) during the study. Hepatotoxin concentrations in surface sediment remained low (<5 microg/kg dw; ELISA) throughout the study. Laboratory experiments indicated that prawn hepatopancreas, heart, and brain were primary organs for hepatotoxin bioaccumulation. Toxin concentration in other organs, including muscle, was less effective. Orally administered nodularin levels in hepatopancreas rapidly decreased from initial 830 to 250 microg/kg dw in 96 h. Similarly, concentration of microcystin-LR injected in prawns decreased from 130 to 30 microg/kg dw (hepatopancreas) in 2 h. These results demonstrate that potential risks caused by cyanobacteria in prawn farming (farmers, prawns, and consumers) were not substantial in 2001-2002. Although prawns may act as vectors for toxin transfer, they did not accumulate alerting amounts of hepatotoxins and were able to effectively detoxify them. Because bloom toxicity may vary, low-frequency toxin monitoring is recommended.

Animals↗

PubMed2001

Isolation, characterization and quantification of microcystins (heptapeptides hepatotoxins) in Microcystis aeruginosa dominated bloom of Lalla Takerkoust lake-reservoir (Morocco).

This paper presents the first data on the identification, characterization and quantification of microcystins isolated from both an extract of a cyanobacteria natural bloom, collected from a eutrophic Moroccan reservoir (Lalla Takerkoust, Marrakesh) and an isolated strain cultivated under laboratory conditions. The isolation and purification of toxins was performed by reverse phase HPLC and then characterized by amino acid analysis and fast atom bombardment mass spectrometry (FAB-MS). Chemical characterization of the toxins from the bloom revealed variants of microcystins such as Mcyst-LR, Mcyst-RR, Mcyst-YR and [D-Asp3]Mcyst-LR. However, the Microcystis aeruginosa strain produced only Mcyst-RR. Using an ELISA assay the total microcystin contents of eight bloom samples collected from 1994 to 1997 ranged from 0.7 to 8.8 microg/mg of lyophilized material. The two isolated Microcystis strains contained higher amounts of microcystins (0.65 microg/ mg of dry weight) than the Pseudanabaena strains (0.021 microg/mg of dry weight). Our results show that the presence of cyanobacteria toxins in water used for drinking in a North African country may be regarded as an health hazard. These results are a contribution to the knowledge of the biogeography of toxic cyanobacteria and their toxins, namely in north African countries.

Bacterial Toxins↗

PubMed2001

Cyanobacteria diversity and toxicity in a wastewater treatment plant (Portugal).

Cyanobacteria are common in eutrophic natural waters. Being favoured by warm, stable and nutrient-enriched waters they may constitute an important part of the phytoplankton community in Wastewater Treatment Plants (WWTP). The phytoplankton communities of two ponds (facultative and maturation) of the WWTP of Esmoriz (North Portugal) were studied, with particular importance given to cyanobacteria. Mouse bioassays were performed with cyanobacteria samples during some of the blooms and ELISA assays specific for hepatotoxic microcystins were carried out. During the study period (January-July 1999) cyanobacteria were frequently dominant in the ponds ranging from 15.2 to 99.8% of the total phytoplankton density. The main species were Planktothrix mougeotii, Microcystis aeruginosa and Pseudanabaena mucicola. Mouse bioassays were performed during Oscillatoria bloom period but the results were negative, in spite of the high cyanobacteria biomass. ELISA assays were performed for both ponds but only in the maturation pond positive values were found. Microcystin concentrations (as MCYST-LR equivalents) varied from 2.3 to 56.0 micrograms/l on the margin of the pond and between 1.7 and 4.6 micrograms/l in the outflow of this pond. These values indicate that WWTP may be a source of contamination of water bodies with cyanobacteria toxins.

Animals↗

PubMed2001

Effects of pyridaphenthion on growth of five freshwater species of phytoplankton. A laboratory study.

The acute toxicity of the insecticide and acaricide pyridaphenthion to five species of freshwater phytoplankton, Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris, Chlorella saccharophila and Pseudanabaena galeata was determined. Insecticide concentrations eliciting a 50% growth reduction over 96 h (EC50) ranged from 2.2 to 30.9 mg/l. The two species of Chlorella and the cyanobacteria P. galeata were more tolerant than the two species of Scenedesmus. Concentrations of pyridaphenthion detected in some natural waters were less than the toxic threshold for these species.

Dose-Response Relationship, Drug↗

PubMed2005

Isolation and identification of antifungal and antialgal alkaloids from Haplophyllum sieversii.

Bioassay-guided fractionation of the hexane/ethyl acetate/water (H/EtOAc/H2O) crude extract of the aerial parts of Haplophyllum sieversii was performed because of preliminary screening data that indicated the presence of growth inhibitory components against Colletotrichum fragariae, Colletotrichum gloeosporioides, and Colletotrichum acutatum. Fractionation was directed using bioautographical methods resulting in the isolation of the bioactive alkaloids flindersine, anhydroevoxine, haplamine, and a lignan eudesmin. These four compounds were evaluated for activity against C. fragariae, C. gloeosporioides, C. acutatum, Botrytis cinerea, Fusarium oxysporum, and Phomopsis obscurans in a dose-response growth-inhibitory bioassay at 50.0, 100.0, and 150.0 microM. Of the four compounds tested, flindersine demonstrated the highest level of antifungal activity. Additionally, flindersine, eudesmin, and haplamine were screened against the freshwater phytoplanktons Oscillatoria perornata, Oscillatoria agardhii, Selenastrum capricornutum, and Pseudanabaena sp. (strain LW397). Haplamine demonstrated selective inhibition against the odor-producing cyanobacterium O. perornata compared to the activity against the green alga S. capricornutum, with lowest observed effect concentration values of 1.0 and 10.0 microM, respectively.

Alkaloids↗