| mercury analysis of acid- and alkaline-reduced biological samples: identification of meta-cinnabar as the major biotransformed compound in algae. | the biotransformation of hg(ii) in ph-controlled and aerated algal cultures was investigated. previous researchers have observed losses in hg detection in vitro with the addition of cysteine under acid reduction conditions in the presence of sncl2. they proposed that this was the effect of hg-thiol complexing. the present study found that cysteine-hg, protein and nonprotein thiol chelates, and nucleoside chelates of hg were all fully detectable under acid reduction conditions without previous di ... | 2006 | 16391065 |
| toxicity of the cyanobacterium limnothrix ac0243 to male balb/c mice. | a growing list of freshwater cyanobacteria are known to produce toxic agents, a fact which makes these organisms of concern to water authorities. a cultured strain of limnothrix (ac0243) was recently shown to have toxic effects in in vitro bioassays. it did not produce any of the known cyanobacterial toxins. the intrapertoneal toxicity of aqueous extracts of the material was therefore tested in mice to determine whether the observed effects might be of public health relevance to drinking water s ... | 2011 | 22119368 |
| novel toxic effects associated with a tropical limnothrix/geitlerinema-like cyanobacterium. | the presence of a toxic strain of a fine filamentous cyanobacterium belonging to the oscillatorialean family pseudanabaenacea was detected during a survey of cyanobacterial taxa associated with the presence of cylindrospermopsin in dams in central queensland (australia). the strain, ac0243, was isolated and cultured, its genomic dna extracted and 16s rna gene sequenced. phylogenetic analysis placed ac0243 with limnothrix species, although this genus appears polyphyletic. moreover, not all morpho ... | 2011 | 19950362 |
| detecting the phosphate status of phytoplankton by enzyme-labelled fluorescence and flow cytometry. | the novel phosphatase substrate, elf-97 phosphate, yields intensely green fluorescent precipitates of elf-97 alcohol (elfa) upon enzymatic dephosphorylation, and thereby traces phosphatase activity back to its producer. in this study, we show that elfa fluorescence is a useful tool in flow cytometric analysis of natural phytoplankton populations. presence of endogenous fluorescent pigments allowed flow cytometric distinction of clusters in the phytoplankton community in lake loosdrecht (the neth ... | 2004 | 19712428 |
| improved fatty acid detection in micro-algae and aquatic meiofauna species using a direct thermal desorption interface combined with comprehensive gas chromatography-time-of-flight mass spectrometry. | comprehensive two-dimensional gas chromatography (gc x gc) with time-of-flight mass spectrometry detection is used to profile the fatty acid composition of whole/intact aquatic microorganisms such as the common fresh water green algae scenedesmus acutus and the filamentous cyanobacterium limnothrix sp. strain mri without any sample preparation steps. it is shown that the technique can be useful in the identification of lipid markers in food-web as well as environmental studies. for instance, new ... | 2008 | 18295771 |
| covariation between zooplankton community composition and cyanobacterial community dynamics in lake blaarmeersen (belgium). | the cyanobacterial community composition in the mesotrophic lake blaarmeersen was determined by denaturing gradient gel electrophoresis (dgge) of pcr-amplified 16s rrna gene fragments during two consecutive years to assess the importance of different classes of explanatory variables (bottom-up and top-down factors, physical variables and phytoplankton) in cyanobacterial community dynamics. the most dominant cyanobacteria in lake blaarmeersen were synechococcus (three genotypes), limnothrix redek ... | 2008 | 18093143 |
| biotransformation of hg(ii) by cyanobacteria. | the biotransformation of hg(ii) by cyanobacteria was investigated under aerobic and ph-controlled culture conditions. mercury was supplied as hgcl(2) in amounts emulating those found under heavily impacted environmental conditions where bioremediation would be appropriate. the analytical procedures used to measure mercury within the culture solution, including that in the cyanobacterial cells, used reduction under both acid and alkaline conditions in the presence of sncl(2). acid reduction detec ... | 2007 | 17071784 |
| stratification by cyanobacteria in lakes: a dynamic buoyancy model indicates size limitations met by planktothrix rubescens filaments. | the ability of the planktothrix rubescens to stratify in lake zürich is related to the size and shape of the cyanobacterial filaments. detailed measurements made in the lake are used in a dynamic computer model of buoyancy regulation to investigate the vertical movements of filaments tracking the depth at which the irradiance would support neutral buoyancy. the movement of the filament lags behind the constantly changing target depth owing to (a) the time taken for the filament to respond to the ... | 2005 | 16219076 |
| 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 th ... | 2005 | 15688255 |
| molecular characterization of cyanobacterial diversity in a shallow eutrophic lake. | we have studied the diversity of pelagic cyanobacteria in lake loosdrecht, the netherlands, through recovery and analysis of small subunit ribosomal rna gene sequences from lake samples and cyanobacterial isolates. we used an adapted protocol for specific amplification of cyanobacterial rdna for denaturing gradient gel electrophoresis (dgge) analysis. this protocol enabled direct comparison of cyanobacterial community profiles with overall bacterial profiles. the theoretical amplification specif ... | 2005 | 15683397 |
| isolation and molecular characterization of a multicellular cyanobacterium, limnothrix/pseudanabaena sp. strain abrg5-3. | a cyanobacterium, semi-filamentous multicellular strain abrg5-3, was isolated and its unique nature was characterized. this axenic strain formed colonies and was motile on an agarose plate. the 16s rrna gene of abrg5-3 exhibited similarities to those of the limnothrix and pseudanabaena strains, which are known as filamentous and nonheterocystous cyanobacteria. peaks in absorbance for the accumulation of chlorophyll a, phycocyanin, and phycoerythrin were observed in the cell extract. natural sepa ... | 2010 | 20834156 |
| phenotypic and genetic diversification of pseudanabaena spp. (cyanobacteria). | pseudanabaena species are poorly known filamentous bloom-forming cyanobacteria closely related to limnothrix. we isolated 28 pseudanabaena strains from the baltic sea (bs) and the albufera de valencia (av; spain). by combining phenotypic and genotypic approaches, the phylogeny, diversity and evolutionary diversification of these isolates were explored. analysis of the in vivo absorption spectra of the pseudanabaena strains revealed two coexisting pigmentation phenotypes: (i) phycocyanin-rich (pc ... | 2009 | 18769459 |
| taxonomic revision of water-bloom-forming species of oscillatorioid cyanobacteria. | a polyphasic approach was used to clarify the taxonomy of the water-bloom-forming oscillatorioid cyanobacteria. seventy-five strains of oscillatorioid cyanobacteria were characterized by 16s rdna sequence analysis, dna base composition, dna-dna hybridization, fatty acid composition, phycobilin pigment composition, complementary chromatic adaptation, morphological characters, growth temperature and salinity tolerance. phylogenetic analysis based on 16s rdna sequences divided the strains into six ... | 2002 | 12361260 |
| isolation and characterization of potentially toxic or harmful cyanobacteria from oaxaca and chiapas, mexico. | the toxic effects of 7 coastal cyanobacterial strains isolated from oaxaca and chiapas, mexico were evaluated. growth was determined by dry weight. toxicity bioassays were done in artemia sp., juvenile white shrimp litopenaeus vannamei and mice mus musculus (icr strain). in shrimp, three feeding methods were implemented: cyanobacterial biomass plus commercial food, cyanobacteria only, and biomass at different concentrations (18, 9, 4.5 and 2.2% w/v). in artemia sp., limnothrix amphigranulata (li ... | 2010 | 20390852 |
| isolation and characterization of exopolysaccharides produced by the cyanobacterium limnothrix redekei pupccc 116. | limnothrix redekei pupccc 116, a filamentous cyanobacterium, has been identified through 16s rrna gene sequencing. exopolysaccharides (eps) of this organism have been isolated and characterized chemically, and its rheological properties were compared with commercial xanthan. the organism produced 304 microg eps/ml culture in 21 days. the rate of eps production was maximum (313 microg eps/mg protein/day) during the initial days of growth, and it decreased to 140 microg eps/mg protein/day during 1 ... | 2010 | 20174886 |