| pesticide (hexachlorocyclohexane) inhibition of growth and nitrogen fixation in blue-green algae anabaenopsis raciborskii and anabaena aphanizomenoides. | the effects of the pesticide hexachlorocyclohexane (hch) on the nitrogen fixing blue-green algae anabaenopsis raciborskii and anabaena aphanizomenoides commonly found as blooms in fish ponds were studied. these algae were very sensitive to hch, and a distinct decrease in growth rate was observed on prolonged incubation. lower concentrations (10 microgram/ml) were algistatic and higher concentrations (60 microgram/ml) were algicidal. the inhibition of nitrogen fixation indicated that the presence ... | 1978 | 80890 |
| the effect of 2,4-dichlorophenoxyacetic acid on growth and nitrogen-fixation of blue-green alga anabaenopsis raciborskii. | sodium salt of 2,4-dichlorophenoxyacetic acid (80% active ingredient), commonly applied for the control of aquatic weeds, was used to observe its effect on the growth and nitrogen fixation of a heterocystous bloom forming blue-green alga anabaenopsis raciborskii. a concentration of 10 microgram per ml of 2,4-d showed stimulation of growth and nitrogen fixation and these were almost unaffected in presence of its 100 microgram per ml in the medium. the alga could tolerate up to 800 microgram per m ... | 1977 | 407848 |
| effects of long-term treatment with acetylene on nitrogen-fixing microorganisms. | long periods of experimental incubation with acetylene led to a multifold enhancement of acetylene-reducing activity in anabaena cylindrica, anabaenopsis circularis, rhodospirillum rubrum, and azotobacter vinelandii. rates of acetylene reduction showed a gradual increase and reached a peak after 2 to 6 h of continuous incubation under acetylene. thereafter, enzyme activity rapidly declined. a similar enhancement of ethylene production was observed when pretreatment with acetylene was interrupted ... | 1977 | 413480 |
| factors influencing dark nitrogen fixation in a blue-green alga. | nitrogen-fixing activity declines first rapidly and then more gradually when anabaenopsis circularis is transferred from light into dark conditions. the rate and duration of dark acetylene reduction (nitrogen fixation) depend upon conditions prevailing during the preceding light period. factors (such as light intensity, co2 concentration, and supply of glucose), which in the light affect photosynthesis and the accumulation of reserve carbon, have a profound effect on dark nitrogen fixation. gluc ... | 1976 | 820251 |
| toxin extraction from an anabaenopsis milleri--dominated bloom. | this paper reports the presence of microcystin type toxins in extracts of a natural bloom of cyanobacteria composed predominantly of anabaenopsis milleri woronichin. the toxins have been extracted, purified and compared to microcystin-lr. the ld50 of a. milleri bloom material was 600-1500 mg lyophilized cells/kg body weight. symptoms and pathological signs of poisoning in mice were characteristic of cyanobacterial hepatotoxins, with enlarged darkened livers with weights of 8-10% of the total bod ... | 1994 | 8191273 |
| rdna analyses of planktonic heterocystous cyanobacteria, including members of the genera anabaenopsis and cyanospira. | the taxonomic coherence and phylogenetic relationships of 11 planktonic heterocystous cyanobacterial isolates were examined by investigating two areas of the rrna operon, the 16s rrna gene (rrns) and the internal transcribed spacer (its) located between the 16s rrna and 23s rrna genes. the rrns sequences were determined for five strains, including representatives of anabaena flos-aquae, aphanizomenon flos-aquae, nodularia sp. and two alkaliphilic planktonic members of the genera anabaenopsis and ... | 2002 | 11832512 |
| salinity effects on growth, photosynthetic parameters, and nitrogenase activity in estuarine planktonic cyanobacteria. | salinity has been suggested as being a controlling factor for blooms of n2-fixing cyanobacteria in estuaries. we tested the effect of salinity on the growth, n2 fixation, and photosynthetic activities of estuarine and freshwater isolates of heterocystous bloom-forming cyanobacteria. anabaena aphanizomenoides and anabaenopsis sp. were isolated from the neuse river estuary, north carolina, and cylindrospermopsis raciborskii from lakes dora and griffin, central florida. salinity tolerance of these ... | 2002 | 12043002 |
| acclimation of chlorophyll a and carotenoid levels to different irradiances in four freshwater cyanobacteria. | this study investigated carotenoid and chlorophyll a (chl-a) contents under two different growth irradiances in four freshwater cyanobacterial strains. we found an increased weight ratio of zeaxanthin to chl-a after exposure to high irradiances over several days. two out of four strains showed higher zeaxanthin amounts on a biomass basis as well. it appears that cyanobacteria enhance their carotenoid pool in response to high light conditions, as increased production of other carotenoids with pho ... | 2006 | 16325961 |
| characterization of macromolecular flocculants produced by phormidium sp. strain j-1 and by anabaenopsis circularis pcc 6720. | several benthic cyanobacteria were found to produce significant amounts of extracellular flocculants. the macromolecular flocculants produced by phormidium sp. strain j-1 and anabaenopsis circularis pcc 6720 were characterized. the phormidium flocculant is a sulfated heteropolysaccharide to which fatty acids and protein are bound. the polysaccharide backbone is composed of uronic acids, rhamnose, mannose, and galactose. the a. circularis flocculant is also an acidic polysaccharide containing ket ... | 1987 | 16347442 |
| toxic cyanobacteria and their toxins in standing waters of kenya: implications for water resource use. | phytoplankton biodiversity studies in kenya's standing waters were carried out between 2001 and 2003. toxin producing cyanobacteria were recorded in twelve water bodies. microcystis and anabaena were the most common species in freshwaters while anabaena and anabaenopsis were common in alkaline saline lakes. seven lakes with cyanobacteria blooms and a hot spring had detectable levels of microcystins and anatoxin-a. cell bound microcystins (lr equivalents) concentration ranged from 1.6-19800 micro ... | 2006 | 16813016 |
| electrophoresis of a toroid along the axis of a cylindrical pore. | the electrophoresis of a toroid (doughnut-shaped entity) along the axis of a long cylindrical pore is analyzed under the conditions of low surface potential and weak applied electric field. the system under consideration is capable of modeling the electrophoretic behavior of various types of biocolloid such as bacterial dna, plasmid dna, and anabaenopsis, in a confined space. the influences of the key parameters of the problem, including the sizes of a toroid, the radius of a pore, and the thick ... | 2006 | 16858727 |
| screening of microalgae for species excreting norharmane, a manifold biologically active indole alkaloid. | a screening of microalgae strains is described, with the objective to discover more species besides the known cyanobacterium nodularia harveyana which excrete the manifold biologically active and co-mutagenic indole alkaloid norharmane (9h-pyrido(3,4-b)indole) into their environment. seven more cyanobacterial species, anabaena cylindrica, anabaena inaequalis, anabaenopsis siamensis, chroococcus minutus, nostoc carneum, nostoc commune and phormidium foveolarum, were newly discovered. the norharma ... | 2008 | 16872816 |
| metabolites produced by cyanobacteria belonging to several species of the family nostocaceae. | this paper provides a comprehensive overview of metabolites, including lipids and lipid-like compounds, nitrogen metabolites, oligopeptides and amino acid derivatives, produced by cyanobacteria of the genera anabaenopsis, aphanizomenon, aulosira, cylindrospermopsis, cylindrospermum, nodularia, and richelia of the family nostocaceae. | 2006 | 17004647 |
| morphological and phylogenetic analysis of anabaenopsis abijatae and anabaenopsis elenkinii (nostocales, cyanobacteria) from tropical inland water bodies. | anabaenopsis spp. are heterocytous cyanobacteria commonly found in tropical, subtropical, and temperate water bodies. so far, the knowledge about the phylogeny of this genus is poor. therefore, we have isolated 15 anabaenopsis spp. strains from kenyan and mexican alkaline and saline water bodies and from a ugandan freshwater body and studied the morphology and phylogeny in a polyphasic approach. morphologically, the investigated strains could be discriminated in two groups. one group was contain ... | 2008 | 17704858 |
| electrophoresis of a charge-regulated toroid normal to a large disk. | the electrophoresis of a charge-regulated toroid (doughnut-shaped entity) normal to a large disk is investigated under the conditions of low surface potential and weak applied electric field. the system considered is capable of modeling the electrophoretic behavior of various types of biocolloids such as bacterial dna, plasmid dna, and anabaenopsis near a perfectly conducting planar wall. the influences of the size of the toroid, the separation distance between the toroid and the disk, the charg ... | 2008 | 18081198 |
| molecular detection of uncultured cyanobacteria and aminotransferase domains for cyanotoxin production in sediments of different kenyan lakes. | pcr-based denaturing gradient gel electrophoresis (dgge) analysis of 16s rrna gene fragments was used to identify the cyanobacterial phylotypes in sediments and plankton of saline-alkaline and freshwater lakes of kenya. the detection of the aminotransferase domain located on modules mcye and ndaf using specific molecular markers confirmed the presence of potential toxin-producing cyanobacteria. the eight nucleotide sequences obtained from dgge bands were placed in three divergent cyanobacterial ... | 2009 | 19416349 |
| microcystin-producing blooms of anabaenopsis arnoldi in a potable mountain lake in saudi arabia. | this study reports for the first time the presence of anabaenopsis arnoldi blooms in saudi freshwaters. this species has been investigated with high cell densities (3.8 x 10(3)-264 x 10(3) cells ml(-1)) during june-november 2007 in tendaha lake, one of the major freshwater sources in saudi arabia. high temperature and conductivity, and a high concentration of phosphate, and low nitrate concentrations may have contributed to the formation of these blooms. the blooms were found to produce microcys ... | 2009 | 19453492 |
| paralytic shellfish poisoning toxin-producing cyanobacterium aphanizomenon gracile in northeast germany. | neurotoxic paralytic shellfish poisoning (psp) toxins, anatoxin-a (atx), and hepatotoxic cylindrospermopsin (cyn) have been detected in several lakes in northeast germany during the last 2 decades. they are produced worldwide by members of the nostocalean genera anabaena, cylindrospermopsis, and aphanizomenon. although no additional sources of psp toxins and atx have been identified in german water bodies to date, the observed cyn concentrations cannot be produced solely by aphanizomenon flos-aq ... | 2010 | 20048055 |
| dynamics of the water bloom-forming microcystis and its relationship with physicochemical factors in lake xuanwu (china). | china's freshwater subtropical shallow lakes are increasingly eutrophic and susceptible to production of heavy growths or water blooms of cyanobacteria. one example was the heavy water bloom that occurred for the first time in lake xuanwu, in 2005, an urban lake located in nanjing city. the aim of the present study was to determine dynamics of water bloom dominating microcystis in this lake. meanwhile, the relationship between environmental factors and microcystis populations was also analyzed. | 2010 | 20512630 |
| first report of anatoxin-a-producing cyanobacterium aphanizomenon issatschenkoi in northeastern germany. | the neurotoxin anatoxin-a (atx), has been detected in several northeast german lakes during the last two decades, but no atx producers have been identified in german water bodies so far. in 2007 and 2008, we analyzed phytoplankton composition and atx concentration in lake stolpsee (ne germany) in order to identify atx producers. sixty-one aphanizomenon spp. strains were isolated, morphologically and phylogenetically characterized, and tested for atx production potential by liquid chromatography- ... | 2010 | 20615427 |