Publications

microcystin production in benthic mats of cyanobacteria in the nile river and irrigation canals, egypt.	the present study describes for the first time the species composition and toxicity of benthic cyanobacteria forming mats on the nile river and irrigation canal sediments in egypt. a total of 19 species of cyanobacteria were isolated from these mats during this study. the toxicity of the extracts of these species was investigated using artemia salina assay, mouse bioassay and enzyme linked immunosorbent assay (elisa). the results showed that all the 19 benthic species isolated from cyanobacteria ...	2006	16564062
nutrient modulated alkaline phosphatase and associated processes in diazotrophic cyanobacteria.	nutrient regulation of alkaline phosphatase (phosphomonoesterase - pmease) was studied in some diazotrophic cyanobacterial strains like anabaena variabilis, anabaena torulosa, calothrix brevissima, scytonema javanicum and hapalosiphon intricatus, in response to the macronutrients (phosphate, calcium and magnesium) and the micronutrients (zinc, copper, iron and manganese). the phosphate grown cells of cyanobacterial strains when transferred to the phosphate deficient medium, showed expression of ...	2006	16878605
characterization of diatom-cyanobacteria symbioses on the basis of nifh, hetr and 16s rrna sequences.	richelia intracellularis is a symbiotic heterocystous cyanobacterium that is capable of forming associations with several genera of diatoms. nifh, 16s rrna and hetr sequences were amplified and cloned from field populations of richelia associated with hemiaulus hauckii (n. atlantic), with rhizosolenia clevei (n. pacific), and from a cultivated isolate of calothrix associated with chaetoceros from station aloha (n. pacific). sequence identity was highest (98.2%) among the 16s rrna sequences, and ...	2006	17014491
cyanobacteria and their toxins in treated-water storage reservoirs in abha city, saudi arabia.	occurrence of toxic cyanobacteria in drinking and recreational waters poses human health at risk as they can release potent toxins into the water. in the present study, open and covered treated-water storage reservoirs as well as their relevant tap waters in abha city, saudi arabia, were surveyed for the presence of cyanobacteria and their toxins. the results revealed the contamination of most open reservoir and tap waters by algae and cyanobacteria, with an abundance of toxigenic species of cya ...	2007	17451766
homologous expression of a bacterial phytochrome. the cyanobacterium fremyella diplosiphon incorporates biliverdin as a genuine, functional chromophore.	bacteriophytochromes constitute a light-sensing subgroup of sensory kinases with a chromophore-binding motif in the n-terminal half and a c-terminally located histidine kinase activity. the cyanobacterium fremyella diplosiphon (also designated calothrix sp.) expresses two sequentially very similar bacteriophytochromes, cyanobacterial phytochrome a (cpha) and cyanobacterial phytochrome b (cphb). cyanobacterial phytochrome a has the canonical cysteine residue, by which covalent chromophore attachm ...	2007	17388813
epilithic cyanobacterial communities of a marine tropical beach rock (heron island, great barrier reef): diversity and diazotrophy.	the diversity and nitrogenase activity of epilithic marine microbes in a holocene beach rock (heron island, great barrier reef, australia) with a proposed biological calcification "microbialite" origin were examined. partial 16s rrna gene sequences from the dominant mat (a coherent and layered pink-pigmented community spread over the beach rock) and biofilms (nonstratified, differently pigmented microbial communities of small shallow depressions) were retrieved using denaturing gradient gel elec ...	2007	17416688
strains of the cyanobacterial genera calothrix and rivularia isolated from the baltic sea display cryptic diversity and are distantly related to gloeotrichia and tolypothrix.	strains of the cyanobacterial genus calothrix display pronounced tapering filaments. these cyanobacteria are benthic, have a worldwide distribution and are among the most easily recognizable cyanobacterial genera. however, it is not clear whether cyanobacterial strains assigned to the genus calothrix constitute a natural monophyletic group. we sequenced 16s rrna genes from 42 cyanobacterial cultures and environmental samples belonging to the genus calothrix, and the morphologically similar gener ...	2007	17466025
domain interaction in cyanobacterial phytochromes as a prerequisite for spectral integrity.	two phytochromes, cpha and cphb, from the cyanobacterium calothrix pcc7601, with similar size (768 and 766 amino acids) and domain structure, were investigated for the essential length of their protein moiety required to maintain the spectral integrity. both proteins fold into pas-, gaf-, phy-, and histidine-kinase (hk) domains. cpha binds a phycocyanobilin (pcb) chromophore at a "canonical" cysteine within the gaf domain, identically as in plant phytochromes. cphb binds biliverdin ixalpha at cy ...	2007	17522854
cyanobacteria as bioreactors for the synthesis of au, ag, pd, and pt nanoparticles via an enzyme-mediated route.	common anabaena, calothrix, and leptolyngbya cyanobacteria are shown to form au, ag, pd, and pt nanoparticles of well-controlled size. these nanoparticles are synthesized intra-cellularly, and naturally released in the culture medium, where they are stabilized by algal polysaccharides, allowing their easy recovery. the size of the recovered particles as well as the reaction yield is shown to depend on the cyanobacteria genus. investigations of nanoparticle formation indicate that the intracellul ...	2007	17685286
genetic and morphological characterization of rivularia and calothrix (nostocales, cyanobacteria) from running water.	in this study, a polyphasic approach was adopted to investigate natural freshwater (river and stream) samples of rivularia colonies and isolated strains of cyanobacteria with a high degree of trichome tapering (genera rivularia and calothrix). analysis of the phycocyanin (pc) operon and the intervening intergenic spacer (cpcba-igs) and 16s rrna gene sequences were used for genetic characterization. in addition, a molecular fingerprinting method, temperature-gradient gel electrophoresis, which al ...	2008	18218948
removal of colour from textile effluent using cyanobacterial biomass.	the cyanobacterial species were isolated from fresh water pond of gura-vishnoiyan and were tested for their ability to decolourise the textile effluent. the reduction in colour of textile effluent with the use of dry biomass of cylindrospermum indicum, nostoc calcicola, calothrix weberi was comparatively observed after 2, 4 and 6 days, but maximum colour absorption was observed after 6 days. calothrix weberi was found the most effective species of cyanobacteria, which can remove the colour inten ...	2008	19295090
physiological characterization and electron microscopic investigation of cyanobacteria associated with wheat rhizosphere.	physiological attributes of a set of cyanobacterial strains, isolated from the rhizosphere of wheat (var. hd 2687), identified as belonging to the genera calothrix (n = 3), westiellopsis (1), hapalosiphon (2) and nostoc (2), were axenized and evaluated. the concentrated culture filtrates of three cyanobacterial strains - c. ghosei, h. intricatus and nostoc sp. were able to enhance germination percentage, radicle and coleoptile length in inhibition experiments with wheat seeds. indole-3-acetic ac ...	2009	19330544
the photoreactions of recombinant phytochrome cpha from the cyanobacterium calothrix pcc7601: a low-temperature uv-vis and ftir study.	the photoreactions of recombinant phytochrome cpha from cyanobacterium calothrix sp. pcc7601 reconstituted with phycocyanobilin were investigated using uv-vis and fourier transform infrared (ftir) difference spectroscopy, stabilizing intermediates at low temperature. the yield of the forward reaction strongly depends on temperature, unlike the backward reaction. because of the very fast thermal relaxation processes in the pr to pfr pathway, no pure difference spectra of the pr photoconversion pr ...	2009	18764898
distribution and activity of diazotrophs in the eastern equatorial atlantic.	the gene abundance and gene expression of six diazotroph populations from the eastern equatorial atlantic in june 2007 were examined using nifh gene quantitative polymerase chain reaction (q pcr) methods. of all the diazotrophs, trichodesmium spp. was the most abundant with the highest number of gene copies in the gulf of guinea. trichodesmium also had the highest nitrogenase gene transcript abundance overall with the maximum in samples collected at the equator and in waters influenced by the co ...	2009	19175790
very-long-chain iso and anteiso branched fatty acids in n-acylphosphatidylethanolamines from a natural cyanobacterial mat of calothrix sp.	a combination of tlc, esi-ms/ms and gc-ms was used to identify unusual molecular species of n-acylphosphatidylethanolamines containing very-long-chain anteiso branched fatty acids (vlcfas) from calothrix sp. collected in antarctica and determine their component vlcfa up to 33-methyltetratriacontanoic acid as picolinyl ester derivatives using gc-ms.	2009	19272619
sesquiterpenes of the geosmin-producing cyanobacterium calothrix pcc 7507 and their toxicity to invertebrates.	the occurrence of sesquiterpenes was investigated with the geosmin-producing cyanobacterium calothrix pcc 7507. the essential oil obtained by vacuum destillation was studied in more detail by gc-ms methods and superposition with authentic compounds. geosmin was the dominating compound while the other sesquiterpenes were minor components. sesquiterpenes that have not been described before in cyanobacteria were isodihydroagarofuran, eremophilone and 6,11-epoxyisodaucane. closed-loop stripping anal ...	2009	19323266
photosynthetic microorganism-mediated synthesis of akaganeite (beta-feooh) nanorods.	common anabaena and calothrix cyanobacteria and klebsormidium green algae are shown to form intracellularly akaganeite beta-feooh nanorods of well-controlled size and unusual morphology at room temperature. x-ray diffraction (xrd), transmission electron microscopy (tem), and scanning electron microscopy x-ray energy dispersive spectrometry (sem-eds) analyses are used to investigate particle structure, size, and morphology. a mechanism involving iron-siderophore complex formation is proposed and ...	2009	19572505
distribution of heterocyst glycolipids in cyanobacteria.	thirty-four axenic strains of cyanobacteria were analysed for their glycolipid content using high performance liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (hplc/esi-ms(2)). species of the families nostocaceae and rivulariaceae, capable of biosynthesising heterocysts, contained a suite of glycolipids consisting of sugar moieties glycosidically bound to long-chain diols, triols, keto-ols and keto-diols. the aglycone moiety consisted of c(26) or c(28) carbon-cha ...	2009	19772975
host selection of symbiotic cyanobacteria in 31 species of the australian cycad genus: macrozamia (zamiaceae).	the nitrogen-fixing cyanobacterium nostoc is a commonly occurring terrestrial and aquatic cyanobacterium often found in symbiosis with a wide range of plant, algal, and fungal species. we investigated the diversity of cyanobacterial species occurring within the coralloid roots of different macrozamia cycad species at diverse locations throughout australia. in all, 74 coralloid root samples were processed and 56 endosymbiotic cyanobacteria were cultured. dna was isolated from unialgal cultures an ...	2010	20459320
morphological and genetic diversity of symbiotic cyanobacteria from cycads.	the morphological and genetic diversity of cyanobacteria associated with cycads was examined using pcr amplification techniques and 16s rrna gene sequence analysis. eighteen symbiotic cyanobacteria were isolated from different cycad species. one of the symbiotic isolates was a species of calothrix, a genus not previously reported to form symbioses with cycadaceae family, and the remainder were nostoc spp. axenic cyanobacterial strains were compared by dna amplification using pcr with either shor ...	2010	20473963
abundance and distribution of major groups of diazotrophic cyanobacteria and their potential contribution to n₂ fixation in the tropical atlantic ocean.	the abundances of six n₂-fixing cyanobacterial phylotypes were profiled at 22 stations across the tropical atlantic ocean during june 2006, and used to model the contribution of the diazotrophs to n₂ fixation. diazotroph abundances were measured by targeting the nifh gene of trichodesmium, unicellular groups a, b, c (ucyn-a, ucyn-b and ucyn-c), and diatom-cyanobiont symbioses hemiaulus-richelia, rhizosolenia-richelia and chaetoceros-calothrix. west to east gradients in temperature, salinity and ...	2010	20678117
phylogenetic and molecular clock inferences of cyanobacterial strains within rivulariaceae from distant environments.	heterocyst-forming cyanobacteria are important players at both evolutionary and ecological scales, but to date it has been difficult to establish their phylogenetic affiliations. we present data from a phylogenetic and molecular clock analysis of heterocystous cyanobacteria within the family rivulariaceae, including the genera calothrix, rivularia, gloeotrichia and tolypothrix. the strains were isolated from distant geographic regions including fresh and brackish water bodies, microbial mats fro ...	2011	21208268
phenotypic variability and phylogenetic relationships of tolypothrix and calothrix (nostocales, cyanobacteria) from running water.	the taxonomy of heterocystous cyanobacteria belonging to the genera calothrix and tolypothrix has long been a matter of debate, but their phylogenetic relationships are still not well understood. our aim was to compare the phylogeny and morphology of members of these genera, which exhibit basal-apical polarity. a phylogeny was reconstructed on the basis of 16s rrna gene sequences and compared with the morphological characterisation of new isolates and environmental samples. strains isolated from ...	2011	21317280
nitrogen fixation and transfer in open ocean diatom-cyanobacterial symbioses.	many diatoms that inhabit low-nutrient waters of the open ocean live in close association with cyanobacteria. some of these associations are believed to be mutualistic, where n(2)-fixing cyanobacterial symbionts provide n for the diatoms. rates of n(2) fixation by symbiotic cyanobacteria and the n transfer to their diatom partners were measured using a high-resolution nanometer scale secondary ion mass spectrometry approach in natural populations. cell-specific rates of n(2) fixation (1.15-71.5? ...	2011	21451586
Morphological and molecular characterization of Calothrix isolates obtained from diverse environments in India.	Abstract-Thirty cyanobacterial strains of Calothrix (family Rivulariaceae) isolated from diverse geographical regions of India were analyzed using morphological and molecular approaches. Most of the isolates were planktonic while some grew benthically. Significant differences were observed with regard to the shape and size of the vegetative cells, heterocysts, and akinetes. Analyses of molecular polymorphisms using Restriction Fragment Length Polymorphisms (RFLP) of 16S rRNA genes with the refer ...	2011	21861379
biochemical effect of carbaryl on oxidative stress, antioxidant enzymes and osmolytes of cyanobacterium calothrix brevissima.	carbaryl is used in indian agriculture for control of rice field pests and it is next to benzene hexachloride in pesticide consumption. in present study, carbaryl (0, 10, 20, 30 and 40 mg/l) induced toxic effects were observed after 21 days exposure on a non target rice field biofertilizer calothrix brevissima with special reference to oxidative stress, antioxidant enzymes and osmolytes. at 40 mg/l carbaryl the decrease in carotenoid, chlorophyll, phycobilin and protein were 63%, 43%, 40% and 40 ...	2011	21979138
Cyanobacteria-mediated phenylpropanoids and phytohormones in rice (Oryza sativa) enhance plant growth and stress tolerance.	Phenylpropanoids, flavonoids and plant growth regulators in rice (Oryza sativa) variety (UPR 1823) inoculated with different cyanobacterial strains namely Anabaena oryzae, Anabaena doliolum, Phormidium fragile, Calothrix geitonos, Hapalosiphon intricatus, Aulosira fertilissima, Tolypothrix tenuis, Oscillatoria acuta and Plectonema boryanum were quantified using HPLC in pot conditions after 15 and 30-ádays. Qualitative analysis of the induced compounds using reverse phase HPLC and further confirm ...	2011	21732035