| strain characterization and classification of oxyphotobacteria in clone cultures on the basis of 16s rrna sequences from the variable regions v6, v7, and v8. | a major problem in development of a polyphasic taxonomy is that the identification of oxyphotobacterial strains (cyanobacteria and prochlorophytes) in culture collections may be incorrect. we have therefore developed a diagnostic system using the dna sequence polymorphism in the 16s rrna regions v6 to v8 for individual strain characterization and identification. pcr primers amplifying v6 to v8 from oxyphotobacteria in unialgal cultures were constructed. direct solid-phase or cyclic sequencing wa ... | 1997 | 9212409 |
| seasonal variations in microcystin contents of danish cyanobacteria. | one hundred ninety-eight of 296 phytoplankton net samples, collected from danish fresh waters during 1993-1995, contained microcystins when analyzed by high-performance liquid chromatography (hplc), and the seasonal variations in microcystin contents were examined. three genera, anabaena, microcystis, and planktothrix, with microcystin-production potential were found. the highest percentage of the samples dominated by anabaena and microcystis was found in june-july and july-november, respectivel ... | 1997 | 9285913 |
| evolution of cyanobacteria by exchange of genetic material among phyletically related strains. | the cyanobacterial radiation consists of several lineages of phyletically (morphologically and genetically) related organisms. several of these organisms show a striking resemblance to fossil counterparts. to investigate the molecular mechanisms responsible for stabilizing or homogenizing cyanobacterial characters, we compared the evolutionary rates and phylogenetic origins of the small-subunit rrna-encoding dna (16s rdna), the conserved gene rbcl (encoding d-ribulose 1,5-bisphosphate carboxylas ... | 1998 | 9642201 |
| rapid identification of the new anabaenopeptin g from planktothrix agardhii hub 011 using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. | toxic water blooms from cyanobacteria in lakes and rivers are a worldwide phenomenon. a new technique is presented for the rapid detection of toxic and nontoxic blooms. matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (maldi-tofms) was employed to identify mainly peptide metabolites (microcystins, anabaenopeptins, cyanopeptolins, microviridins, microginins and aeruginosins) from microgram quantities of prepared cells within minutes. the spectra show the presence of pe ... | 1999 | 10209871 |
| nh4+ utilization and regeneration rates in freshwater lakes determined by gc-ms of derivatised dihydroindophenol. | a new gas chromatographic-mass spectrometric method was established that is applicable for the determination of nh4+ utilization and regeneration rates in freshwater. hollow-fibre modules were used to stop the biogenic nitrogen-fluxes by separating the particulate from the dissolved matter. incubations were performed in tedlar bags (polyvinylfluoride), which enabled repeated sample removals through teflon tubes, making the calculation of nitrogen-fluxes in accordance to blackburn and caperon muc ... | 1999 | 10395465 |
| the diversity of gas vesicle genes in planktothrix rubescens from lake zürich. | part of the gas vesicle gene cluster was amplified by pcr from three strains of planktothrix rubescens isolated from lake zürich, switzerland. each contains multiple alternating copies of gvpa and gvpc. all of the gvpa sequences in the different strains are identical. there are two types of gvpc: gvpc20, of length 516 bp, encodes a 20 kda protein of 172 amino acid residues (whose n-terminal amino acid sequence is homologous with the sequence of gvpc in planktothrix [oscillatoria] agardhii); gvpc ... | 1999 | 10537197 |
| the relationship between critical pressure and width of gas vesicles in isolates of planktothrix rubescens from lake zürich. | the mean critical collapse pressure (p(c)) of gas vesicles in 81 strains of the cyanobacterium planktothrix rubescens from lake zürich, switzerland, was bimodally distributed between a minimum of 0.86 mpa and a maximum of 1.17 mpa. measurements were made of the cylinder diameter (d) of gas vesicles isolated from seven of the strains. the mean diameter, which varied from 48 to 61 nm, was inversely related to p(c), in keeping with the theory of strength of thin-walled rigid cylinders. these measur ... | 1999 | 10537198 |
| gas vesicle genes in planktothrix spp. from nordic lakes: strains with weak gas vesicles possess a longer variant of gvpc. | in cyanobacteria of the genus planktothrix:, there are three length variants of gvpc, the gene that encodes the outer protein of the gas vesicle. sequence analyses indicated that the three allelic variants of gvpc differ principally in the presence or absence of a 99 nt and a 213 nt section. strains with the new variant, gvpc(28), which encodes a 28 kda form of gvpc, produce gas vesicles that collapse at the relatively low critical pressure (p(c)) of 0.61-0.75 mpa. the authors have identified 12 ... | 2000 | 10931905 |
| application of sequence-specific labeled 16s rrna gene oligonucleotide probes for genetic profiling of cyanobacterial abundance and diversity by array hybridization. | dna sequence information for the small-subunit rrna gene (16s rdna) obtained from cyanobacterial cultures was used to investigate the presence of cyanobacteria and their abundance in natural habitats. eight planktonic communities developing in lakes characterized by relatively low algal biomass (mesotrophic) and in lakes with correspondingly high biomass (eutrophic) were selected for the study. the organismal compositions of the water samples were analyzed genetically, using multiplex sequence-s ... | 2000 | 10966421 |
| site-specific restriction endonucleases in cyanobacteria. | planktic cyanobacteria were screened for endodeoxyribonucleases. principal component analysis (pca) was employed to demonstrate a potential relationship between certain enzymes and a group of cyanobacteria. the data were obtained from a data bank and this study. | 2000 | 11123471 |
| 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 ... | 2001 | 11268858 |
| molecular characterization of planktic cyanobacteria of anabaena, aphanizomenon, microcystis and planktothrix genera. | toxic and non-toxic cyanobacterial strains from anabaena, aphanizomenon, calothrix, cylindrospermum, nostoc, microcystis, planktothrix (oscillatoria agardhii), oscillatoria and synechococcus genera were examined by rflp of pcr-amplified 16s rrna genes and 16s rrna gene sequencing. with both methods, high 16s rrna gene similarity was found among planktic, anatoxin-a-producing anabaena and non-toxic aphanizomenon, microcystin-producing and non-toxic microcystis, and microcystin-producing and non-t ... | 2001 | 11321098 |
| occurrence of microcystins in raw water sources and treated drinking water of finnish waterworks. | problems caused by cyanobacteria are common around the world and also in raw water sources of drinking water treatment plants. strains belonging to genera microcystis, anabaena and planktothrix produce potent hepatotoxins, the microcystins. laboratory and pilot scale studies have shown that microcystins dissolved in water may pass the conventional surface water treatment processes. in 1998 the world health organization proposed a guide value of 1 microgram/l for microcystin-lr (mc-lr) in drinkin ... | 2001 | 11464762 |
| isolation of new protein phosphatase inhibitors from two cyanobacteria species, planktothrix spp. | two new protein phosphatase inhibitors, oscillamide b (1) and c (2), were isolated from the cyanobacteria planktothrix (oscillatoria) agardhii and p. rubescens. the structures of the inhibitors were elucidated by analysis of hrfabms, 1d and 2d nmr spectra, and chemical degradation. these inhibitors are ureido-containing cyclic peptides and inhibited serine/threonine protein phosphatases pp1 and pp2a. the inhibitory activities were closely related to the arg and n-me-hty residues in the peptides. | 2001 | 11520225 |
| high grazer toxicity of [d-asp(3),(e)-dhb(7)]microcystin-rr of planktothrix rubescens as compared to different microcystins. | planktothrix rubescens, the dominant cyanobacterium in lake zürich, is generally considered to be toxic to zooplankton. the major toxin was determined by nmr spectroscopy and chemical analysis to be [d-asp(3),(e)-dhb(7)]microcystin-rr. the compound was isolated in high purity, and its 24-h acute grazer toxicity was compared with microcystin-lr, microcystin-rr, microcystin-yr, and nodularin using a thamnocephalus platyurus bioassay. based on lc(50) values [d-asp(3),(e)-dhb(7)]microcystin-rr was t ... | 2001 | 11600156 |
| urban impact in the history of water quality in the stockholm archipelago. | from the historical perspective, the increasing number of inhabitants in the city of stockholm has had a negative effect on water quality in the surrounding lakes and coastal region. government control and measures taken to improve water quality have been in progress since the mid-19th century. water conditions in the 19th century, compared to later years is difficult to assess from the first chemical and biological investigations, due to infrequent sampling and the different parameters and meth ... | 2001 | 11697262 |
| biological effect of the planktothrix sp. fp1 cyanobacterial extract. | cyanobacteria are common and potentially harmful inhabitants of freshwater and marine environments worldwide. some waterbloom-forming cyanobacteria are toxic and they may cause animal death and adversely affect human health. a filamentous freshwater cyanobacterium, planktothrix sp. fp1, was found to be responsible for a toxic algal bloom in lake varese (italy) during august of 1997. in the present study, the biological effects of the planktothrix sp. fp1 cell extract on xenopus embryos and on hu ... | 2002 | 11711123 |
| presence of planktothrix sp. and cyanobacterial toxins in lake ammersee, germany and their impact on whitefish (coregonus lavaretus l.). | due to the increasing oligotrophy of lake ammersee, southern germany, metalimnic planktothrix have become one of the dominant planktonic species causing regular blooms. whitefish (coregonus lavaretus) is the dominant local fish species with great importance for the fishing industry. recently, whole age groups of this fish species have disappeared and since 1991, average body-weight has decreased. the causes for this remain unclear. planktothrix species produce the cyclic peptide toxin desmethyl ... | 2001 | 11769245 |
| the purine degradation pathway: possible role in paralytic shellfish toxin metabolism in the cyanobacterium planktothrix sp. fp1. | the paralytic shellfish toxins (psts) are potent neurotoxic alkaloids and their major biological effect is due to the blockage of voltage-gated sodium channels in excitable cells. they have been recognised as an important health risk for humans, animals, and ecosystems worldwide. the metabolic pathways that lead to the production and the degradation of these toxic metabolites are still unknown. in this study, we investigated the possible link between pst accumulation and the activation of the me ... | 2001 | 11800428 |
| cellular fatty acids as chemotaxonomic markers of the genera anabaena, aphanizomenon, microcystis, nostoc and planktothrix (cyanobacteria). | the cellular fatty acid content of 22 cyanobacterial strains belonging to the genera anabaena, aphanizomenon, calothrix, cylindrospermum, nostoc, microcystis and planktothrix were analysed. the identities of the major peaks were confirmed by ms. correspondence analysis of the data revealed three distinct groups formed by the microcystis strains, the nostoc/planktothrix strains and the anabaena/aphanizomenon/cylindrospermum strains. the calothrix strain did not cluster with the other heterocystou ... | 2002 | 12054217 |
| the cpcb-cpca locus as a tool for the genetic characterization of the genus arthrospira (cyanobacteria): evidence for horizontal transfer. | to investigate the genetic diversity of the genus arthrospira and to compare it with other cyanobacteria, sequences of 670 nt from the phycocyanin operon were determined for 23 natural, cultivated or commercial strains of arthrospira and compared with sequences from 20 other non-arthrospira cyanobacterial strains. the sequenced dna fragment comprises the last 255 nt of cpcb, the cpcb-cpca spacer and the first 304 nt of cpca. the resulting phylogenetic tree confirms that the genus arthrospira is ... | 2002 | 12054250 |
| toxicity and microcystin content of extracts from a planktothrix bloom and two laboratory strains. | toxic effects and microcystin content from various extracts of a planktothrix agardhii bloom and two different strains of planktothrix agardhii, hub 076, and niva 34 were investigated. extracts were obtained with solvents of different polarity such as hexane, dichloromethane, methanol, and water. additionally, different pre-treatments were used to break the cells before extraction. acute toxicity was determined with the fairy shrimp thamnocephalus platyurus, subchronic effects were detected in e ... | 2002 | 12092588 |
| removal of cyanobacterial microcystin-lr by ferrate oxidation-coagulation. | in this study, the effect of a multiple function reagent-ferrate on the removal of microcystins-lr (mclr) from freeze-dried planktothrix sp. was investigated. the toxin was easily decomposed by oxidation with ferrate, and the removal efficiency depended on the dosage of ferrate, ph, and contact time. simultaneously the reduction product fe(oh)(3) after ferrate oxidation could flocculate the organic compounds so that 50% toc removal of the extract was reached. the low residual iron reflected the ... | 2002 | 12165315 |
| [admadda5]-microcystins in planktothrix agardhii strain ph-123 (cyanobacteria)--importance for monitoring of microcystins in the environment. | two major and two minor microcystins (mcyst) were isolated from a hepatotoxic danish strain of planktothrix agardhii (gomont) anagnostidis et komárek by reversed-phase high-performance liquid chromatography. the microcystins were characterized by uv spectroscopy, amino acid analysis, fast atom bombardment mass spectrometry (fabms), and high-resolution fabms. the major microcystins were further analysed by collisionally induced tandem electrospray ionization ms. the microcystins were found to be ... | 2002 | 12203956 |
| applications of maldi-tof ms analysis in cyanotoxin research. | recent advances in analytical chemistry have provided an array of techniques to analyze cyanotoxins in a variety of samples. mass spectral analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (maldi-tof ms) has proven to be a reliable and rapid tool to detect and identify microcystin variants in very small samples such as single microcystis colonies. mass signals presumptive of microcystin variants can be characterized further and identified by postsource-deca ... | 2002 | 12203959 |
| production of drinking water from raw water containing cyanobacteria--pilot plant studies for assessing the risk of microcystin breakthrough. | toxins in cyanobacteria are a recognized risk in the treatment of drinking-water treatment. cyanotoxins can occur in two modifications: cell bound and dissolved in water. the process of toxin release may occur naturally, but it also may be induced through the processes of drinking-water treatment. both causes of release are relevant to the safety of drinking water. this study investigated cyanotoxin release and elimination through different treatment trains in systematic pilot-scale studies with ... | 2002 | 12203960 |
| 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 |
| spontaneous mutations in gas vesicle genes of planktothrix spp. affect gas vesicle production and critical pressure. | wild-type strains of the cyanobacterium planktothrix rubescens have a cluster of gas vesicle (gvp) genes with repeats of alternating gvpa and gvpc. the gvpc occurs in three length variants, all with the same 3'-sequence, omegac. spontaneous non-buoyant mutants had lost some of the alternating gvpac copies and their gvpc genes had a novel 3'-end sequence, psic; additional gvpc genes terminating in this sequence were also found in the wild-type and representatives of other gv genotypes. alleles of ... | 2002 | 12399034 |
| genetic diversity within populations of cyanobacteria assessed by analysis of single filaments. | we have developed a technique for determining the genetic structure of populations of filamentous cyanobacteria. the sequence diversity at specific gene loci is first characterised in a range of clonal cultures; subsequent analysis involves individual trichomes collected directly from natural populations. this technique has been used to examine the population genetic structure of nodularia in the baltic sea and planktothrix in lake zürich. for nodularia, studies utilising four polymorphic loci r ... | 2002 | 12448718 |
| microcystin biosynthesis in planktothrix: genes, evolution, and manipulation. | microcystins represent an extraordinarily large family of cyclic heptapeptide toxins that are nonribosomally synthesized by various cyanobacteria. microcystins specifically inhibit the eukaryotic protein phosphatases 1 and 2a. their outstanding variability makes them particularly useful for studies on the evolution of structure-function relationships in peptide synthetases and their genes. analyses of microcystin synthetase genes provide valuable clues for the potential and limits of combinatori ... | 2003 | 12511503 |
| the first identification of the rare cyanobacterial toxin, homoanatoxin-a, in ireland. | the first identification of the rare cyanobacterial neurotoxin, homoanatoxin-a, in ireland is reported. a sensitive fluorimetric liquid chromatographic (lc) method was applied to the analysis of homoanatoxin-a in the low microg/l range. the analysis of the anatoxins in water samples required weak cation exchange solid phase extraction, fluorimetric derivatisation with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (nbd-f), and isocratic reversed-phase lc. confirmation of toxin identity was made using lc ... | 2003 | 12565752 |
| oscillapeptin j, a new grazer toxin of the freshwater cyanobacterium planktothrix rubescens. | oscillapeptin j (1), a new and highly potent crustacean grazer toxin, was isolated from the axenic cyanobacterium planktothrix rubescens, which frequently forms blooms in freshwater lakes. chemical and spectroscopic analyses, including high resolving ms and two-dimensional nmr, were used to elucidate the compound's structure as a depsiheptapeptide of the oscillapeptin type. strict application of a bioassay-guided isolation procedure proved this compound to be one of the major causative agents (b ... | 2003 | 12662108 |
| detection of prochlorothrix in brackish waters by specific amplification of pcb genes. | prochlorothrix hollandica is the only filamentous chlorophyll b (chlb)-containing oxyphotobacterium that has been found in freshwater habitats to date. chlb serves as a light-harvesting pigment which is bound to special binding proteins (pcb). even though prochlorothrix was initially characterized as a highly salt-sensitive species, we detected it in a brackish water environment that is characterized by salinities of up to 12 practical salinity units. using pcr and reverse transcription, we ampl ... | 2003 | 14532086 |
| pcr-based identification of microcystin-producing genotypes of different cyanobacterial genera. | microcystins are harmful hepatotoxins produced by many, but not all strains of the cyanobacterial genera anabaena, microcystis, anabaena, planktothrix, and nostoc. waterbodies have to be monitored for the mass development of toxic cyanobacteria; however, because of the close genetic relationship of microcystin-producing and non-producing strains within a genus, identification of microcystin-producers by morphological criteria is not possible. the genomes of microcystin-producing cells contain mc ... | 2003 | 14551674 |
| quantitative real-time pcr for determination of microcystin synthetase e copy numbers for microcystis and anabaena in lakes. | cyanobacterial mass occurrences in freshwater lakes are generally formed by anabaena, microcystis, and planktothrix, which may produce cyclic heptapeptide hepatotoxins, microcystins. thus far, identification of the most potent microcystin producer in a lake has not been possible due to a lack of quantitative methods. the aim of this study was to identify the microcystin-producing genera and to determine the copy numbers of microcystin synthetase gene e (mcye) in lake tuusulanjärvi and lake hiide ... | 2003 | 14660378 |
| genes coding for hepatotoxic heptapeptides (microcystins) in the cyanobacterium anabaena strain 90. | the cluster of microcystin synthetase genes from anabaena strain 90 was sequenced and characterized. the total size of the region is 55.4 kb, and the genes are organized in three putative operons. the first operon (mcya-mcyb-mcyc) is transcribed in the opposite direction from the second operon (mcyg-mcyd-mcyj-mcye-mcyf-mcyi) and the third operon (mcyh). the genes mcya, mcyb, and mcyc encode nonribosomal peptide synthetases (nrps), while mcyd codes for a polyketide synthase (pks), and mcyg and mc ... | 2004 | 14766543 |
| occurrence of toxic planktothrix rubescens blooms in lake nantua, france. | cyanobacteria including genus oscillatoria are known to release toxins into waterbodies. to study the occurrence of toxic blooms in lake nantua, the planktothrix rubescens species (oscillatoria rubescens) was considered. at the same time, some physicochemical parameters were analysed to estimate their impact on toxin production. the investigations were conducted during summertime and the highest toxin concentration analysed by hplc was detected in august (10.8 microg/l of lake water). the result ... | 2004 | 15033326 |
| seco[d-asp3]microcystin-rr and [d-asp3,d-glu(ome)6]microcystin-rr, two new microcystins from a toxic water bloom of the cyanobacterium planktothrixrubescens. | two novel microcystins, seco[d-asp(3)]microcystin-rr (1) and [d-asp(3),d-glu(ome)(6)]-microcystin-rr (2), along with the known [d-asp(3)]microcystin-rr (3), were isolated from a planktothrix rubescens toxic bloom collected in lake bled, slovenia. the structures were deduced using one- and two-dimensional nmr techniques, esims/cid/ms analysis, and marfey's method for determining the amino acids' absolute stereochemistry. compounds 1 and 3 exhibit weak pp1 inhibitory activity. the nmr data of comp ... | 2004 | 15043406 |
| anatoxin-a toxin in the cyanobacterium planktothrix rubescens from a fishing pond in northern italy. | a heavy algal bloom occurring in a fishing pond in northern italy full of salmo trutta was examined for algae taxonomy and toxic production. the dominant algal species (98%) was identified as the cyanobacterium planktothrix rubescens (d.c. ex gomont) komarek anagnostidis, based on morphological examination, and it was revealed to be toxic in mouse and vibrio fischeri bioassays. the toxin was identified as anatoxin-a using high-performance liquid chromatography and confirmed using liquid chromato ... | 2004 | 15101034 |
| abundance of active and inactive microcystin genotypes in populations of the toxic cyanobacterium planktothrix spp. | to investigate the abundance of active and inactive microcystin genotypes in populations of the filamentous cyanobacterium planktothrix spp., individual filaments were grown as clonal strains in the laboratory and analysed for microcystin synthetase (mcy) genes and microcystin. twenty-three green-pigmented strains of p. agardhii originating mostly from shallow water bodies fell into two groups, those possessing mcya and those lacking mcya. in contrast, all of the 49 strains that were assigned to ... | 2004 | 15250885 |
| a dhb-microcystin from the filamentous cyanobacterium planktothrix rubescens. | a dhb-microcystin variant was isolated from the filamentous cyanobacterium planktothrix rubescens. its structure was elucidated as (e)-dhb-microcystin-hilr ([d-asp3, (e)-dhb7]microcystin-hilr) on the basis of spectral data and amino acid analysis after acid hydrolysis. | 2004 | 15279989 |
| diversity of coexisting planktothrix (cyanobacteria) chemotypes deduced by mass spectral analysis of microystins and other oligopeptides. | cyanobacteria are reported to produce secondary metabolites of which toxic and bioactive peptides are of scientific and public interest. many peptides are synthesized by the non-ribosomal peptide synthesis pathway and their presence is a stable feature of individual clones. we isolated 18 clonal strains of planktothrix from a single water sample from lake maxsee near berlin and analyzed them by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, hplc, and pcr for their ... | 2004 | 15322739 |
| determination of microcystin variants and related peptides present in a water bloom of planktothrix (oscillatoria) rubescens in a spanish drinking water reservoir by lc/esi-ms. | a water bloom of planktothrix (oscillatoria) rubescens was observed in a drinking water reservoir in central spain in 2003. microcystins where analysed by lc/esi-ms in 21 samples collected from this reservoir in five different days between march and may. a demethylated variant of microcystin-rr was identified as the major microcystin in most samples. trace levels of microcystin-lr, -rr and -yr were detected in some samples. four less common microcystins, with [m+h]+ ions at m/z 960, 981, 1045 an ... | 2004 | 15530970 |
| development of a universal microarray based on the ligation detection reaction and 16s rrna gene polymorphism to target diversity of cyanobacteria. | the cyanobacteria are photosynthetic prokaryotes of significant ecological and biotechnological interest, since they strongly contribute to primary production and are a rich source of bioactive compounds. in eutrophic fresh and brackish waters, their mass occurrences (water blooms) are often toxic and constitute a high potential risk for human health. therefore, rapid and reliable identification of cyanobacterial species in complex environmental samples is important. here we describe the develop ... | 2004 | 15574913 |
| different gvpc length variants are transcribed within single filaments of the cyanobacterium planktothrix rubescens. | transcripts of the gas vesicle genes gvpa and gvpc were detected in single filaments of the cyanobacterium planktothrix rubescens using reverse transcription and quantitative real-time pcr. primers were designed to amplify short sequences within gvpa and three length variants of gvpc. with genomic template dna, and using sybr green to monitor product accumulation, similar amplification efficiencies were observed for each of these genes. the relative copy numbers of gvpc length variants in genomi ... | 2005 | 15632425 |
| 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 |
| 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 |
| genetic contributions to the risk assessment of microcystin in the environment. | of the known toxins produced by cyanobacteria, microcystins and nodularins are the most significant threat to human and animal health. knock-out studies have confirmed that microcystins are produced nonribosomally by a multienzyme complex consisting of peptide synthetases, polyketide synthases, and tailoring enzymes. gene clusters for microcystin biosynthesis have been identified and sequenced in the distantly related cyanobacterial genera microcystis, planktothrix, and anabaena. homologous gene ... | 2005 | 15737674 |
| variability of the microcystin synthetase gene cluster in the genus planktothrix (oscillatoriales, cyanobacteria). | in populations of planktothrix, microcystin-producers and non-producers, which are morphologically identical, coexist. in order to develop a basis for the reliable detection of microcystin producers in field samples with polymerase chain reaction (pcr) based methods, we studied the presence and variability of eight regions of the mcy gene cluster in 46 planktothrix strains, including both microcystin-producing and non-producing ones. pcr-amplification products for two mcy gene regions were also ... | 2005 | 15837386 |
| genetic identification of microcystin ecotypes in toxic cyanobacteria of the genus planktothrix. | microcystins (mcs) are toxic heptapeptides which are synthesized by the filamentous cyanobacterium planktothrix and other genera via non-ribosomal peptide synthesis. mcs share the common structure cyclo(-d-ala1-l-x2-d-erythro-beta-iso-aspartic acid3-l-z4-adda5-d-glu6-n-methyl-dehydroalanine7) [adda; (2s, 3s, 8s, 9s)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid], in which numerous mc variants have been reported. in general, the variation in structure is due to different amino ... | 2005 | 15870462 |
| toxic cyanobacteria and microcystin concentrations in a public water supply reservoir in the brazilian amazonia region. | toxic cyanobacteria in public water supply reservoirs represent a serious health risk as they can release potent cyanotoxins into the water. in the present study we analyzed surface water collected from the utinga reservoir, the main source of drinking water for the city of belem-pa, in order to characterize the reservoir's cyanobacterial biota and to determine the toxicity of these organisms and the concentration of microcystins in raw and treated water. the cyanobacterial biota included potent ... | 2005 | 15904685 |
| distribution of microcystins in a lake foodweb: no evidence for biomagnification. | microcystins, toxins produced by cyanobacteria, may play a role in fish kills, although their specific contribution remains unclear. a better understanding of the eco-toxicological effects of microcystins is hampered by a lack of analyses at different trophic levels in lake foodwebs. we present 3 years of monitoring data, and directly compare the transfer of microcystin in the foodweb starting with the uptake of (toxic) cyanobacteria by two different filter feeders: the cladoceran daphnia galeat ... | 2005 | 16052377 |
| the microcystin composition of the cyanobacterium planktothrix agardhii changes toward a more toxic variant with increasing light intensity. | the cyanobacterium planktothrix agardhii, which is dominant in many shallow eutrophic lakes, can produce hepatotoxic microcystins. currently, more than 70 different microcystin variants have been described, which differ in toxicity. in this study, the effect of photon irradiance on the production of different microcystin variants by p. agardhii was investigated using light-limited turbidostats. both the amount of the mrna transcript of the mcya gene and the total microcystin production rate incr ... | 2005 | 16151102 |
| contrasting microcystin production and cyanobacterial population dynamics in two planktothrix-dominated freshwater lakes. | microcystin concentrations in two dutch lakes with an important planktothrix component were related to the dynamics of cyanobacterial genotypes and biovolumes. genotype composition was analysed by using denaturing gradient gel electrophoresis (dgge) profiling of the intergenic transcribed spacer region of the rrn operon (rrna-its), and biovolumes were measured by using microscopy. in lake tjeukemeer, microcystins were present throughout summer (maximum concentration 30 microg l(-1)) while cyanob ... | 2005 | 16156725 |
| frequency of inhibitors of daphnid trypsin in the widely distributed cyanobacterial genus planktothrix. | recent findings showed that inhibition of the digestive enzyme trypsin by cyanobacterial metabolites can result in the death of the microcrustacean daphnia. compounds that are active against daphnid trypsin can therefore be considered as potentially toxic to daphnia. here we reported on the frequency of such compounds in the widely distributed cyanobacterial genus planktothrix. of the 89 planktothrix strains analysed, about 70% produced inhibitors of daphnid trypsin. the strains tested positive ... | 2005 | 16156739 |
| spatial dominance and inorganic carbon assimilation by conspicuous autotrophic biofilms in a physical and chemical gradient of a cold sulfurous spring: the role of differential ecological strategies. | the community composition and ecophysiological features of microbial autotrophic biofilms were studied in fuente podrida, a cold sulfur spring located in east spain. we demonstrated how different ecophysiological strategies, such as resistance and/or utilization of sulfide and oxygen, light adaptation, or resistance to high water flow, allow each of the microorganisms described to efficiently colonize several areas within the environmental gradient. in the zone of the spring constantly influence ... | 2005 | 16211325 |
| 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 |
| acclimation of the diatom stephanodiscus neoastraea and the cyanobacterium planktothrix agardhii to simulated natural light fluctuations. | functional and structural characteristics of the photosynthetic apparatus were studied in the diatom stephanodiscus neoastraea and the cyanobacterium planktothrix agardhii which were grown semi-continuously under constant irradiance or under simulated natural light fluctuations. the light fluctuations consisted of 24 oscillations of exponentially increasing and decreasing irradiance over a 12-h light period. maximum irradiance was 1100 mumol photons m(-2) s(-1) with the ratio of maximum to minim ... | 2002 | 16228538 |
| 16s rdna analyses of the cyanobacterial microbiota through the water-column in a boreal lake with a metalimnic planktothrix population. | the planktothrix population in lake steinsfjord has attracted particular attention, due to the potential development of toxic blooms. this population is special in the sense that mass developments of planktothrix occur in the metalimnion. we investigated the distribution of planktothrix, as well as other cyanobacteria, through the water-column during a planktothrix mass development at 10-16 m depth. the analyses were done by chlorophyll measurements, microscopy, and by a recently developed 16s r ... | 2005 | 16239195 |
| variations in the microcystin production of planktothrix rubescens (cyanobacteria) assessed from a four-year survey of lac du bourget (france) and from laboratory experiments. | between 1999 and 2002, a routine survey of water quality in the lac du bourget was performed to study the dynamics and microcystin (mc) production of planktothrix rubescens. using liquid chromatography coupled to diode array detection and mass spectrometry, we found that two main variants ([d-asp3] and [d-asp3, dhb7] microcystin-rr) were produced. the proportion of these two variants was not influenced by the depth or season of sampling. expressed in microcystin-lr equivalents, high microcystin ... | 2005 | 16328657 |
| the burgundy-blood phenomenon: a model of buoyancy change explains autumnal waterblooms by planktothrix rubescens in lake zürich. | buoyancy changes of the cyanobacterium planktothrix rubescens- the burgundy-blood alga - were modelled from its buoyancy response to light and irradiance changes in lake zürich during autumnal mixing. the daily insolation received by filaments at fixed depths and circulating to different depths was calculated from the measured light attenuation and surface irradiance. the active mixing depth, za5, was determined from the vertical turbulent diffusion coefficient, kz, calculated from the wind spee ... | 2006 | 16390423 |
| transposons inactivate biosynthesis of the nonribosomal peptide microcystin in naturally occurring planktothrix spp. | the filamentous cyanobacteria planktothrix spp. occur in the temperate region of the northern hemisphere. the red-pigmented planktothrix rubescens bacteria occur in deep, physically stratified, and less eutrophic lakes. planktothrix is a known producer of the toxic heptapeptide microcystin (mc), which is produced nonribosomally by a large enzyme complex consisting of peptide synthetases and polyketide synthases encoded by a total of nine genes (mcy genes). planktothrix spp. differ in their cellu ... | 2006 | 16391033 |
| microcystins (cyanobacterial toxins) in surface waters of rural bangladesh: pilot study. | in bangladesh the exposure of millions of inhabitants to water from (shallow) tube wells contaminated with high geogenic loads of arsenic is a major concern. as an alternative to the costly drilling of deep wells, the return to the use of surface water as a source of drinking water is considered. in addition to the well-known hazards of water borne infectious diseases associated with the use of surface water, recently the potential public health implications of toxic cyanobacteria have been reco ... | 2005 | 16459839 |
| microcystin analysis in single filaments of planktothrix spp. in laboratory cultures and environmental blooms. | single filaments of planktothrix spp. were isolated from laboratory cultures of p. agardhii (nies 595) and p. rubescens (sl 03) and from four freshwater lakes in england and turkey. filament lengths were measured and microcystins were extracted by freeze-thawing and boiling. microcystin analysis of the isolated single filaments was performed by elisa using antibodies raised against microcystin-lr with a minimum detection limit (mdl) of 11 pg filament(-1). in some cases a high percentage of the f ... | 2006 | 16597454 |
| evaluation of different dna sampling techniques for the application of the real-time pcr method for the quantification of cyanobacteria in water. | to evaluate different types of sample storage and dna extraction techniques for the real-time pcr quantification of cyanobacteria in water. | 2006 | 16599997 |
| determination of cyanobacterial diversity during algal blooms in daechung reservoir, korea, on the basis of cpcba intergenic spacer region analysis. | the detection and prevention of cyanobacterial blooms are important issues in water quality management. as such, the diversity and community dynamics of cyanobacteria during cyanobacterial bloom in the daechung reservoir, korea, were studied by analyzing the intergenic spacer (igs) region between phycocyanin subunit genes cpcb and cpca (cpcba igs). to amplify the cpcba igs from environmental samples, new pcr primers that could cover a wider range of cyanobacteria than previously known primers we ... | 2006 | 16672464 |
| a cyanobacterial lps antagonist prevents endotoxin shock and blocks sustained tlr4 stimulation required for cytokine expression. | toll-like receptors (tlrs) function as primary sensors that elicit coordinated innate immune defenses through recognition of microbial products and induction of immune and proinflammatory genes. here we report the identification and biological characterization of a lipopolysaccharide (lps)-like molecule extracted from the cyanobacterium oscillatoria planktothrix fp1 (cyanobacterial product [cyp]) that is not stimulatory per se but acts as a potent and selective antagonist of bacterial lps. cyp b ... | 2006 | 16717116 |
| oral toxicity of the microcystin-containing cyanobacterium planktothrix rubescens in european whitefish (coregonus lavaretus). | the microcystin-producing cyanobacterium planktothrix is one of the most widespread genera amongst toxin producing cyanobacteria in european lakes. in particular, the metalimnic blooms of planktothrix rubescens have been associated with growing problems in the professional freshwater fishery as a decrease in yearly yields in the important coregonids fishery often coincides with the appearance of p. rubescens. p. rubescens is a cyanobacterial species known to produce toxic compounds, e.g. microcy ... | 2006 | 16806524 |
| diversity of microcystin-producing cyanobacteria in spatially isolated regions of lake erie. | the diversity of microcystin-producing cyanobacteria in the western basin of lake erie was studied using sequence analysis of mcya gene fragments. distinct populations of potentially toxic microcystis and planktothrix were found in spatially isolated locations. this study highlights previously undocumented diversity of potentially toxic cyanobacteria. | 2006 | 16820510 |
| microcystin diversity in a planktothrix rubescens population from lake albano (central italy). | the cyanobacterium planktothrix rubescens anagnostidis & komarek (previously oscillatoria rubescens dc ex gomont) is present in several italian lakes and it is known to produce cyanotoxins. the dynamics and toxin production of p. rubescens population in lake albano, a volcanic crater lake in central italy, has been studied for 5 years (january 2001-april 2005). winter-spring superficial blooms with frequent scums were observed every year. total microcystin (mc) levels were measured from april 20 ... | 2006 | 16828137 |
| interactions between cyanobacteria and gastropods i. ingestion of toxic planktothrix agardhii by lymnaea stagnalis and the kinetics of microcystin bioaccumulation and detoxification. | the last two decades have been marked by an increasing occurrence of toxic cyanobacterial blooms in aquatic ecosystems. these pose an expanding threat to the environment and to human health. among the intracellular toxins produced by cyanobacteria, microcystins (hepatotoxins) are the most frequent and widely studied. as an ubiquitous herbivore living in eutrophic freshwaters, the freshwater snail lymnaea stagnalis (gastropoda: pulmonata) is particularly exposed to cyanobacteria. the toxic filame ... | 2006 | 16837077 |
| detection and monitoring toxigenicity of cyanobacteria by application of molecular methods. | the aim of this study was early genetic identification of microcystin-producing cyanobacteria and monitoring their toxigenicity by determining toxin concentrations in three polish lakes throughout the summer of 2004. the assessment of cyanobacterial blooms was carried out in shallow, eutrophic water bodies: lake jeziorak, lake bninskie, and sulejow reservoir. samples for dna, phycological, and toxin analyses were collected from july till october. molecular analysis of the 16s rrna region was use ... | 2006 | 16841323 |
| application of fast repetition rate fluorometry to phytoplankton photosynthetic parameters in freshwaters. | fast repetition rate fluorometry (frrf) was successfully applied to various studies in modern oceanography. in this study, for the first time, the seasonality of phytoplankton photosynthetic parameters in a deep alpine lake was observed using frrf in combination with the traditional (14)c incubation technique. special attention was given to the differences in photosynthetic behaviour during mixed and stratified conditions, characterised especially during summer by a deep chlorophyll maximum (dcm ... | 2006 | 16847741 |
| sinking velocities of phytoplankton measured on a stable density gradient by laser scanning. | two particular difficulties in measuring the sinking velocities of phytoplankton cells are preventing convection within the sedimenting medium and determining the changing depth of the cells. these problems are overcome by using a density-stabilized sedimentation column scanned by a laser. for freshwater species, a suspension of phytoplankton is layered over a vertical density gradient of percoll solution; as the cells sink down the column their relative concentration is measured by the forward ... | 2006 | 16849271 |
| detection of microcystin-producing cyanobacteria in finnish lakes with genus-specific microcystin synthetase gene e (mcye) pcr and associations with environmental factors. | we studied the frequency and composition of potential microcystin (mc) producers in 70 finnish lakes with general and genus-specific microcystin synthetase gene e (mcye) pcr. potential mc-producing microcystis, planktothrixand anabaena spp. existed in 70%, 63%, and 37% of the lake samples, respectively. approximately two-thirds of the lake samples contained one or two potential mc producers, while all three genera existed in 24% of the samples. in oligotrophic lakes, the occurrence of only one m ... | 2006 | 16957235 |
| the uptake of amino acids by the cyanobacterium planktothrix rubescens is stimulated by light at low irradiances. | the rates of uptake of five amino acids--alanine, glutamate, glycine, leucine and serine--by axenic cultures of the cyanobacterium planktothrix rubescens were measured over a range of irradiances using the (14)c-labelled amino acids at the nanomolar concentrations observed in lake zürich. the rates in the light exceeded the dark rates by as much as two- to ninefold. the light-affinity constants for stimulation were similar, indicating a similar process for each of the five amino acids. the e(k) ... | 2006 | 16958904 |
| multiplex pcr for the detection of toxigenic cyanobacteria in dietary supplements produced for human consumption. | the production of food supplements containing cyanobacteria is a growing worldwide industry. while there have been several reports of health benefits that can be gained from the consumption of these supplements, there have also been a growing number of studies showing the presence of toxins some of which (for example microcystins) are known to affect human health. in this paper, we report a multiplex polymerase chain reaction (pcr) technique that can be used to identify microcystin contamination ... | 2007 | 17001477 |
| diversity of microcystin genotypes among populations of the filamentous cyanobacteria planktothrix rubescens and planktothrix agardhii. | microcystins (mcs) are toxic heptapeptides that are produced by filamentous cyanobacteria planktothrix rubescens and planktothrix agardhii via nonribosomal peptide synthesis. mcs share a common structure cyclo (-d-alanine(1)-l-x(2)- d-erythro-beta-iso-aspartic acid(3)-l-z(4)-adda(5)-d-glutamate(6)- n-methyl-dehydroalanine(7)) where x(2) and z(2) are variable l-amino acids in positions 2, 4 of the molecule. part of the mcyb gene (1,451 bp) that is involved in the activation of the x(2) amino acid ... | 2006 | 17032280 |
| on the reproducibility of microcosm experiments - different community composition in parallel phototrophic biofilm microcosms. | phototrophic biofilms were cultivated simultaneously using the same inoculum in three identical flow-lane microcosms located in different laboratories. the growth rates of the biofilms were similar in the different microcosms, but denaturing gradient gel electrophoresis (dgge) analysis of both 16s and 18s rrna gene fragments showed that the communities developed differently in terms of species richness and community composition. one microcosm was dominated by microcoleus and phormidium species, ... | 2006 | 17064259 |
| toxicity of complex cyanobacterial samples and their fractions in xenopus laevis embryos and the role of microcystins. | this work evaluated the effects of various cyanobacterial fractions in frog embryo teratogenesis assay xenopus (fetax) with african clawed frog embryos. fractions were prepared from five biomasses with different dominant genera (microcystis, aphanizomenon, anabaena, planktothrix) and different microcystin content. effects of following fractions were investigated: (i) homogenate of complex cyanobacterial biomass, (ii) cell debris (pellet) after centrifugation of complex biomass, (iii) supernatant ... | 2006 | 17092578 |
| molecular techniques for the early warning of toxic cyanobacteria blooms in freshwater lakes and rivers. | the aim of this work was to test the efficacy of molecular techniques for detecting toxigenic cyanobacteria in environmental water samples collected from freshwater lakes, rivers and reservoirs in portugal. of 26 environmental samples tested, 21 were found to contain microcystis using a genus-specific polymerase chain reaction (pcr). another primer pair was applied to the same dna template to test for the presence of microcystin synthetase genes. this primer pair resulted in the formation of a p ... | 2007 | 17221193 |
| effect of different cyanobacterial biomasses and their fractions with variable microcystin content on embryonal development of carp (cyprinus carpio l.). | while numerous studies focused on the effects of microcystins, the role of other components of complex cyanobacterial water blooms in toxicity is poorly understood. in this study we have evaluated effects of various fractions of cyanobacterial biomass with different composition and microcystin content on embryolarval development of carp (cyprinus carpio). the following samples (fractions) of four natural water blooms were prepared and tested: complex cyanobacterial biomass, crude aqueous extract ... | 2007 | 17280727 |
| interactions between cyanobacteria and gastropods ii. impact of toxic planktothrix agardhii on the life-history traits of lymnaea stagnalis. | hepatotoxins are frequently produced by many cyanobacterial species. microcystins (mcs) are the most frequent and widely studied hepatotoxins, with potentially hazardous repercussions on aquatic organisms. as a ubiquitous herbivore living in eutrophic freshwaters, the snail lymnaea stagnalis (gastropoda: pulmonata) is particularly exposed to cyanobacteria. the toxic filamentous planktothrix agardhii is common in temperate lakes and is therefore, a potential food resource for gastropods. in the f ... | 2007 | 17292488 |
| physiological stress and pathology in european whitefish (coregonus lavaretus) induced by subchronic exposure to environmentally relevant densities of planktothrix rubescens. | planktothrix rubescens belongs to the most ubiquitous cyanobacterial species in mesotrophic and oligotrophic lakes in the pre-alpine regions. in most of these lakes, coregonids are among the dominant species of the ichthyofauna with great importance for the professional fishery. a possible link between the occurrence of toxic planktothrix blooms and the recurrent slumps in coregonid yields has been suggested. indeed, acute toxic effects of microcystins and other cyanobacterial toxins have been s ... | 2007 | 17320197 |
| isolation and endotoxin activities of lipopolysaccharides from cyanobacterial cultures and complex water blooms and comparison with the effects of heterotrophic bacteria and green alga. | massive cyanobacterial water blooms are serious environmental and health problems worldwide. while some cyanobacterial toxins such as peptide microcystins have been investigated extensively, other toxic components of cyanobacteria (e.g. lipopolysaccharides, lps) are poorly understood. the present study characterized endotoxin activities of lps isolated from (i) laboratory cyanobacterial cultures, (ii) cyanobacterial water bloom samples dominated by microcystis sp., planktothrix sp., aphanizomeno ... | 2008 | 17461433 |
| biosynthesis and structure of aeruginoside 126a and 126b, cyanobacterial peptide glycosides bearing a 2-carboxy-6-hydroxyoctahydroindole moiety. | aeruginosins represent a group of peptide metabolites isolated from various cyanobacterial genera and from marine sponges that potently inhibit different types of serine proteases. members of this family are characterized by the presence of a 2-carboxy-6-hydroxyoctahydroindole (choi) moiety. we have identified and fully sequenced a nrps gene cluster in the genome of the cyanobacterium planktothrix agardhii cya126/8. insertional mutagenesis of a nrps component led to the discovery and structural ... | 2007 | 17524987 |
| molecular characterization of potential microcystin-producing cyanobacteria in lake ontario embayments and nearshore waters. | the distribution and genotypic variation of potential microcystin (mc) producers along the southern and eastern shores of lake ontario in 2001 and 2003 were examined using a suite of pcr primers. cyanobacterial, microcystis sp., and microcystis-specific toxin primer sets identified shoreline distribution of cyanobacterial dna (in 97% of the stations) and mc synthetase genes (in 50% of the stations). sequence analysis of a partial mcya amplicon targeting microcystis, anabaena, and planktothrix sp ... | 2007 | 17526791 |
| consistency between chemotyping of single filaments of planktothrix rubescens (cyanobacteria) by maldi-tof and the peptide patterns of strains determined by hplc-ms. | the high metabolic diversity of potentially toxigenic cyanobacteria has been recently demonstrated for several bloom-forming genera. to understand the dynamics of cyanobacterial blooms and fluctuations in toxin content, techniques are required that allow the distinction of clones in field samples on a subspecific taxonomic level. we evaluated the possibility to analyze single filaments of a common toxigenic taxon, planktothrix rubescens, by comparing peptide profiles obtained from hplc/ms analys ... | 2007 | 17605146 |
| toxic cyanobacterial blooms in reservoirs under a semiarid mediterranean climate: the magnification of a problem. | sicilian reservoirs constitute the most important water resources available on the island. during summer 2001, the intense water utilization of lake arancio reservoir reduced the water level significantly, which coincided with the formation of intense blooms formed by the microcystin (mc)-producing cyanobacterium microcystis aeruginosa. during summer 2003, lake arancio was continuously filled and the vertical stratification of the water column was maintained resulting in five to sixfold lower ce ... | 2007 | 17607731 |
| microcystin ecotypes in a perennial planktothrix agardhii bloom. | the dynamics and microcystins (mc) concentrations of a perennial planktothrix agardhii bloom were investigated in a eutrophic lake (viry-châtillon, france). a weak relationship was observed between p. agardhii population biomass and the mc concentrations in a 1-year survey. to further investigate the causes of mc concentration changes, we concurrently conducted experiments on 41 strains isolated from this lake. we first checked the clonal diversity of p. agardhii population (i) by molecular tech ... | 2007 | 17632212 |
| comparison of cyanopeptolin genes in planktothrix, microcystis, and anabaena strains: evidence for independent evolution within each genus. | the major cyclic peptide cyanopeptolin 1138, produced by planktothrix strain niva cya 116, was characterized and shown to be structurally very close to the earlier-characterized oscillapeptin e. a cyanopeptolin gene cluster likely to encode the corresponding peptide synthetase was sequenced from the same strain. the 30-kb oci gene cluster contains two novel domains previously not detected in nonribosomal peptide synthetase gene clusters (a putative glyceric acid-activating domain and a sulfotran ... | 2007 | 17921284 |
| planktocyclin, a cyclooctapeptide protease inhibitor produced by the freshwater cyanobacterium planktothrix rubescens. | the freshwater cyanobacterium planktothrix rubescens produces the cyclooctapeptide cyclo(pro-gly-leu-val-met-phe-gly-val). the chemical structure is new. this homodetic cyclic octapeptide was named planktocyclin ( 1). it consists solely of proteinogenic l-amino acids and is a strong inhibitor of mammalian trypsin and alpha-chymotrypsin and a moderately active inhibitor of human recombinant caspase-8. mass spectrometric and 2d-nmr spectroscopic data allowed the determination of its structure. syn ... | 2007 | 17935298 |
| effects of cyanobacterial crude extracts from planktothrix agardhii on embryo-larval development of medaka fish, oryzias latipes. | embryonic toxicity from exposure to microcystins, cyclic hepatotoxic heptapeptides from cyanobacteria, receives increasing attention as a public human health biohazard. using a microinjection technology, we have introduced cyanobacterial extracts from planktothrix agardhii directly into the vitellus of late neurula embryos (stage 19) of medaka (oryzias latipes). microinjection (2 nl) of p. agardhii pmc 75.02 extract containing microcystins (mc) resulted in a dose-dependent mortality of embryos. ... | 2008 | 17997465 |
| identification of hepatotoxin-producing cyanobacteria by dna-chip. | we developed a new tool to detect and identify hepatotoxin-producing cyanobacteria of the genera anabaena, microcystis, planktothrix, nostoc and nodularia. genus-specific probe pairs were designed for the detection of the microcystin (mcye) and nodularin synthetase genes (ndaf) of these five genera to be used with a dna-chip. the method couples a ligation detection reaction, in which the polymerase chain reaction (pcr)-amplified mcye/ndaf genes are recognized by the probe pairs, with a hybridiza ... | 2008 | 18190512 |
| [critical collapse pressure of gas vesicles in six strains of cyanobacteria]. | two methods including filtration (vacuity is 0.02 mpa) and centrifugation ( < 500 r/min) were applied to concentrate algal biomass, and capillary compression tube and the concentrated algae suspensions, critical pressure distribution of gas vesicles in six cyanobacteria were also investigated. the results showed that unicellular microcystis aeruginosa cells couldn't be concentrated effectively by filtration or centrifugation, but colony of microcystis wesenbergii and microcystis flosaquae, and f ... | 2007 | 18290422 |
| temporal variations in the dynamics of potentially microcystin-producing strains in a bloom-forming planktothrix agardhii (cyanobacterium) population. | the concentration of microcystins (mcs) produced during blooms depends on variations in both the proportion of strains containing the genes involved in mc production and the mc cell quota (the ratio between the mc concentration and the density of cells with the mcya genotype) for toxic strains. in order to assess the dynamics of mc-producing and non-mc-producing strains and to identify the impact of environmental factors on the relative proportions of these two subpopulations, we performed a 2-y ... | 2008 | 18441113 |
| a cyanobacterial lipopolysaccharide antagonist inhibits cytokine production induced by neisseria meningitidis in a human whole-blood model of septicemia. | septicemia caused by neisseria meningitidis is characterized by increasing levels of meningococcal lipopolysaccharide (nm-lps) and cytokine production in the blood. we have used an in vitro human whole-blood model of meningococcal septicemia to investigate the potential of cyp, a selective toll-like receptor 4 (tlr4)-md-2 antagonist derived from the cyanobacterium oscillatoria planktothrix fp1, for reducing lps-mediated cytokine production. cyp (> or = 1 microg/ml) inhibited the secretion of the ... | 2008 | 18443097 |
| collapse of a planktothrix agardhii perennial bloom and microcystin dynamics in response to reduced phosphate concentrations in a temperate lake. | planktothrix agardhii dynamics, microcystin concentration and limnological variables were monitored every 2 weeks for 2 years (2004-2006) in a shallow hypereutrophic artificial lake (bnv, viry-châtillon, france). time-series analysis identified two components in the p. agardhii biomass dynamics: (1) a significant decreasing trend in p. agardhii biomass (65% of the overall variance) and (2) a residual component without significant seasonal periodicity. a path-analysis model was built to determine ... | 2008 | 18462398 |
| surface charge and zeta-potential of metabolically active and dead cyanobacteria. | zeta potential and acid-base titrations of active, inactivated, and dead planktothrix sp. and synechococcus sp. cyanobacteria were performed to determine the degree to which cell surface electric potential and proton/hydroxyl adsorption are controlled by metabolism or cell membrane structure. surface oh(-) excess from potentiometric data, showed differences in surface charge between active and dead cyanobacteria from ph 3 to 10. average zero salt effect ph (ph(pzse)) of 5.8+/-0.1 and 6.3+/-0.1 w ... | 2008 | 18471824 |
| nontoxic strains of cyanobacteria are the result of major gene deletion events induced by a transposable element. | blooms that are formed by cyanobacteria consist of toxic and nontoxic strains. the mechanisms that result in the occurrence of nontoxic strains are enigmatic. all the nontoxic strains of the filamentous cyanobacterium planktothrix that were isolated from 9 european countries were found to have lost 90% of a large microcystin synthetase (mcy) gene cluster that encoded the synthesis of the toxic peptide microcystin (mc). those strains still contain the flanking regions of the mcy gene cluster alon ... | 2008 | 18502770 |