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PubMed1986

Toxic peptides from freshwater cyanobacteria (blue-green algae). I. Isolation, purification and characterization of peptides from Microcystis aeruginosa and Anabaena flos-aquae.

Toxic peptides from two European Microcystis aeruginosa and one Canadian Anabaena flos-aquae species of freshwater cyanobacteria (blue-green algae) were purified by high performance liquid chromatography (HPLC) and examined by amino acid analysis and mass spectrometry. A toxic fraction from a butanol/methanol extract of toxic lyophilized cells was separated by G-25 gel filtration and purified by HPLC using a C-18 semi-preparative Column. A toxic peak with the same elution time was detected for each of the three toxic cyanobacteria. The desalted purified toxins (i.p. LD50 in mice, 50 micrograms/kg) caused signs of poisoning identical with previous literature reports of hepatotoxic peptides from Microcystis. On hydrolysis and amino acid analysis all three toxins showed a similar profile, consisting of equimolar amounts of glutamic acid, alanine, arginine and leucine. beta-methyl aspartic acid was identified in all of the toxic peptides. The fast atom bombardment mass spectra of the toxins indicated the molecular weight to be 994 for all the peptides. The absence of sequence ions in their corresponding fast atom bombardment mass spectra indicated the peptides to be cyclic.

Amino Acids↗
PubMed1988

Properties of two toxins isolated from the blue-green alga Microcystis aeruginosa.

Attempts were made to characterize the two toxins (P-1 and P-2) isolated from the blue-green alga Microcystis aeruginosa, by amino acid analysis, mass spectrometry, 1H- and 13C-NMR. P-2, the major toxin, had a molecular weight of 1044, and consisted of one molecule each of beta-methylaspartic acid, D-Glu, D-Ala, L-Arg, L-Tyr, N-methyldehydroalanine, and 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid (Adda). P-1, with a molecular weight of 994, appeared to have almost the same composition except that it contained L-Leu instead of L-Tyr in P-2. Mass spectrometric studies, along with a negative ninhydrin reaction, indicated that each toxin was a cyclic peptide. P-2 showed an LD99 of 70 micrograms/kg mice when injected i.p. and [alpha]D24 of -72.42 degrees (c = 0.095 in methanol), and was decomposed at around 218 degrees C.

Amino Acids↗
PubMed1988

Blood pressure and hepatocellular effects of the cyclic heptapeptide toxin produced by the freshwater cyanobacterium (blue-green alga) Microcystis aeruginosa strain PCC-7820.

Laboratory rats and mice were used to investigate the hepatotoxicity caused by the cyclic heptapeptide (mol. wt 994) termed microcystin-LR. Microcystin-LR (also known as cyanoginosin-LR) is produced by the freshwater cyanobacterium (blue-green alga) M. aeruginosa strain PCC-7820. In time course histopathology studies with mice significant liver damage, with an absence of pulmonary emboli, were observed after 15 min. Pulmonary emboli did not appear until 1 hr. In rats, significant liver damage and the presence of occasional emboli were observed at 20 min. Pulmonary emboli did not contain fibrin nor appear life-threatening in any case and resembled the globular eosinophilic debris found in the liver sinusoids and central veins. Measurements of rat femoral arterial, jugular venous and hepatic portal venous blood pressures during the course of toxicity revealed a slowly declining arterial pressure and stable, normal venous pressures. Blood lactic acid levels rose in parallel with the fall in arterial pressure, a pattern typical of hemorrhagic shock. There was no indication of venous congestion that would accompany right heart failure. Isolated, perfused rat livers dosed with toxin showed rapid changes in the liver, including cessation of bile flow within 10 min and complete obliteration of normal lobular architecture within 60 min. No effect of the toxin was observed in isolated perfused rat heart. We conclude that in the mouse and rat, microcystin-LR is a potent, rapid-acting, direct hepatotoxin, with the immediate cause of death in acute toxicities being hemorrhagic shock secondary to massive hepatocellular necrosis and collapse of hepatic parenchyma.

Animals↗
PubMed1994

Electron microscopic studies on experimental poisoning in mice induced by cylindrospermopsin isolated from blue-green alga Umezakia natans.

The effects of cylindrospermopsin isolated from a blue-green alga Umezakia natans on mice were examined morphologically and biochemically. The main target of the phycotoxin was the liver. The thymus, kidneys and heart were also affected. There were four consecutive phases of the pathological changes in the liver. The initial phase was that of inhibition of the protein synthesis, the second phase of membrane proliferation followed, and then the third phase of fat droplet accumulation and finally the phase of cell death. Using globin synthesis in the rabbit reticulocytes system, it was clearly demonstrated that cylindrospermopsin is a potent inhibitor of the protein synthesis. Protein in microsomes from the mouse livers treated by cylindrospermopsin decreased in amount more significantly than that of phospholipid in microsomes. Furthermore, the amount of total P450 was extensively diminished in the toxin treated with hepatic microsomes.

Alkaloids↗
PubMed1984

Structural proteins and lipids in a virus, PBCV-1, which replicates in a Chlorella-like alga.

PBCV-1, a large dsDNA-containing virus which replicates in a Chlorella-like green alga, is composed of approximately 64% protein, 25% DNA, and 5-10% lipid on a weight basis. Polyacrylamide gel electrophoresis of the dissociated virus particle resolves 50 to 60 proteins which range in apparent molecular weight from 10,000 to 135,000. Two of these proteins are glycoproteins and at least four are located on the viral surface. The major lipids are phosphatidyl choline, phosphatidyl ethanolamine, and an unidentified component. The effect of organic solvents, surfactants, and chelating and reducing agents on viral infectivity and ultrastructure are reported. Inhibitor studies established that PBCV-1 protein synthesis occurs on cytoplasmic ribosomes.

Chlorella↗
PubMed1984

Infection of a Chlorella-like alga with the virus, PBCV-1: ultrastructural studies.

Ultrastructural studies revealed that the virus, PBCV-1, adsorbs to the surface of the Chlorella-like green alga NC64A and enzymatically digests a portion of the host cell wall. The viral DNA is then released into the interior of the cell leaving an empty capsid on the surface. Thus uncoating of the viral genome occurs at the surface of its host. PBCV-1 also adsorbs to and digests the host wall of either heat-killed, methanol-extracted, or purified cell wall fragments.

Chlorella↗
PubMed1985

Lytic viruses infecting a Chlorella-like alga.

A number of viruses which form plaques on the unicellular, eukaryotic, Chlorella-like green alga, strain NC64A, were isolated from fresh water ponds and rivers in Illinois, North Carolina, and South Carolina. The viruses were large polyhedrons (160 to 190 nm in diameter) and contained dsDNA genomes of ca. 300 kbp. All of the viral DNAs hybridized with DNA from the previously described PBCV-1 virus. However, the viruses, even many of those isolated from the same water sample, could be distinguished from one another by DNA restriction endonuclease digestion. The viruses, including PBCV-1, were grouped into five classes by their resistance to certain DNA restriction endonucleases. Presumably the DNAs in the five classes contain different types or amounts of modified bases.

Chlorella↗
PubMed1986

Characterization of viruses infecting a eukaryotic Chlorella-like green alga.

Nineteen plaque-forming viruses of the unicellular, eukaryotic Chlorella-like green alga, strain NC64A, were isolated from various geographic regions in the United States and characterized. Like the previously described virus, PBCV-1, all of the new viruses were large polyhedrons, sensitive to chloroform, and contained large dsDNA genomes of ca. 300 kbp. All of the viral DNAs contained 5-methyldeoxycytidine which varied from 0.1 to 47% of the deoxycytidine. In addition, 10 of the viral DNAs contained N6-methyldeoxyadenosine which varied from 8.1 to 37% of the deoxyadenosine. These viruses, along with 11 previously described viruses which replicate in the same Chlorella host, were grouped into 11 classes based on at least one of the following properties: plaque size, reaction with PBCV-1 antiserum, or the nature and abundance of methylated bases in their genomic DNA.

Base Composition↗
PubMed1986

Infection of a Chlorella-like alga with the virus PBCV-1: transcriptional studies.

Infection of the unicellular, eukaryotic Chlorella-like green alga NC64A by the large dsDNA containing virus PBCV-1 immediately reduced host RNA synthesis. Chloroplast rRNAs, but not cytosolic rRNAs, were degraded following viral infection. Northern blot analysis utilizing four cloned fragments of PBCV-1 DNA as probes, which represent about 12% of the viral genome, revealed several properties of PBCV-1 transcription: A few viral transcripts were detected within 5 min after infection. Each PBCV-1 DNA clone hybridized to both early and late transcripts which implies that early and late genes are dispersed throughout the viral genome. The transition from early to late transcription occurred between 40 and 60 min after infection coincident with the onset of viral DNA synthesis. Three of the four DNA clones hybridized to transcripts which additively were larger than the corresponding DNA probe. This could reflect RNA processing, presence of overlapping genes, or transcription from both DNA strands. A few, but not all, early transcripts were synthesized in the presence of cycloheximide. This suggests that the virus either carries in its own RNA polymerase or uses a host RNA polymerase for very early viral transcription and that synthesis of additional, later transcripts depends on translation of an early gene product(s).

Chlorella↗
PubMed1988

A comparison of viruses infecting two different Chlorella-like green algae.

Five plaque-forming viruses (Pbi viruses) of the unicellular, eukaryotic, exsymbiotic Chlorella-like green alga strain Pbi were isolated from fresh water collected in Germany. The viruses were compared to two previously characterized plaque-forming viruses (NC64A viruses) of Chlorella strain NC64A. The Pbi viruses do not infect Chlorella NC64A and vice versa. Like the NC64A viruses the Pbi viruses are large polyhedron with a diameter of 140 to 150 nm, are chloroform sensitive, have many structural proteins, and have large dsDNA genomes of at least 300 kb. However, the Pbi viruses are serologically distinct from the NC64A viruses. The five Pbi virus genomes contain 5-methylcytosine, which varied from 14.2 to 43.1% of the cytosine, and two of them also contained N6-methyladenine. DNAs from the Pbi viruses hybridized poorly with the two NC64A virus DNAs and they have a higher guanine plus cytosine content (ca. 46%) than the NC64A virus DNAs (ca. 40%).

Base Composition↗
PubMed1986

Diterpenes of marine brown algae of the family Dictyotaceae: their possible role as defense compounds and their use in chemotaxonomy.

Marine brown algae of the family Dictyotaceae are protected against predation. Their survival strategy is, at least in part, based on the production of chemical defenses. These compounds are diterpenes that seem to establish a specific predator-prey relationship, and which are found as food-chain markers. The use of Dictyotaceae diterpenes in chemotaxonomy is briefly discussed.

Diterpenes↗
PubMed1986

Radio-iodine in thyroid glands of swans, farm animals and humans, also in algae and river water from the Thames Valley, England.

A highly sensitive counting system has been used to measure radio-iodine in environmental samples from the Thames Valley. Iodine-125 and occasionally iodine-131 have been found in the thyroid glands of most of the swans that have died on the River Thames, the River Wey and the Grand Union Canal, and in algae and water samples from the Thames and many of its tributaries. The presence of this activity is ascribed to the waste discarded into the drainage system by hospitals and research laboratories, reaching the rivers via the effluent from sewage treatment works. The Thames is used as a source of drinking water, particularly in London and its western approaches. Weed and water samples collected from river water abstraction points, reservoirs, tap water supplies, and animal water troughs fed from this supply all contained low levels of iodine-125. The drinking water route can account for the iodine-125 found in the thyroids of farm animals from west Surrey and in a few people living in London. The amounts found constitute a trivial radiation dose to man and animals as they are far below the acceptable limit of exposure for man.

Animals↗
PubMed1991

QSAR for organic chemical bioconcentration in Daphnia, algae, and mussels.

Prediction of the bioconcentration of organic chemicals from water by aquatic organisms has important applications in the management of hazardous chemicals. This study gives a compilation of bioconcentration factors on a wet weight basis (BCFw) of 52 organic chemicals by Daphnia magna from aqueous solution. The bioconcentration factors for the chemicals in Daphnia were successfully correlated with their n-octanol/water partition coefficients (log Kow) using a linear regression analysis. In addition to the ordinary least-square regression technique, the geometric mean regression technique is also used because this takes into account deviations in Kow values. Both results show that the Kow value of a chemical is a good predictor of the BCF in Daphnia. The BCF-Kow relationships between Daphnia, algae (Chlorella), and mussels (Mytilus edulis) are compared with each other.

Animals↗
PubMed1989

Discovery of 12-(S)-hydroxy-5,8,10,14-icosatetraenoic acid [12-(S)-HETE] in the tropical red alga Platysiphonia miniata.

The potent mammalian immunohormone, 12-(S)-hydroxy-5,8,10,14-icosatetraenoic acid (12-(S)-HETE), is a 12-lipoxygenase metabolite of arachidonic acid that is widely distributed in animal tissues. In humans, it is produced and secreted by platelet cells and elicits both chemotactic and degranulatory responses in target neutrophils. As widely as 12-lipoxygenase activity and one of its major products, 12-(S)-HETE, have been found in animal tissues, it has never been found in plants. Herein, we report the first isolation of the 12-lipoxygenase product, 12-(S)-HETE, from a plant, the tropical marine alga Platysiphonia miniata (C. Agardh) Børgesen.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1976

The blue-green alga agmenellum quadruplicatum contains covalently closed DNA circles.

This paper reports the first direct visualization of covalently closed, circular DNA from a blue-green alga. Agmenellum quadruplicatum lysates, fractionated on CsCl-ethidium bromide density gradients, yield a minor band of covalently closed DNA circles which we have analyzed by electron microscopy and agarose gel electrophoresis. The DNA consists of a number of a discrete classes of DNA circles ranging in molecular weight from 3 X 10(6) daltons to 65-80 X 10(6) daltons. The function of these circles is at present entirely unknown.

Centrifugation, Density Gradient↗
PubMed1984

Construction and characterization of autonomously replicating plasmids in the green unicellular alga Chlamydomonas reinhardii.

Plasmids that replicate autonomously in Chlamydomonas reinhardii were constructed by inserting random DNA fragments from this alga into a plasmid containing the yeast ARG4 locus. Arginine prototrophy was used as a selective marker. The presence of free plasmids in the DNA of the transformants was demonstrated by hybridization with a specific plasmid probe and by recovering these plasmids in E. coli after transformation. Four of them were characterized. Their inserts of 415, 257, 153, and 102 bp all hybridize to chloroplast DNA and were localized on the physical map of the chloroplast genome. One of these plasmids also promotes autonomous replication in yeast. Sequence analysis of the inserts of the plasmids reveals several short direct and inverted repeats and two semiconserved AT-rich elements of 19 and 12 bp that may play a role in promoting autonomous replication in C. reinhardii.

Base Sequence↗
PubMed1989

Analysis of an algae-based CELSS. Part 2: options and weight analysis.

Life support components are evaluated for application to an idealized closed life support system which includes an algal reactor for food production. Weight-based trade studies are reported as "break-even" time for replacing food stores with a regenerative bioreactor. It is concluded that closure of the life support gases (oxygen recovery) depends on the carbon dioxide reduction chemistry and that an algae-based food production can provide an attractive alternative to re-supply for longer duration missions.

Ammonia↗
PubMed1994

Effect of simple shear flow on photosynthesis rate and morphology of micro algae.

The convective motion of micro algal suspension gives an advantageous effect on the photosynthetic rate in the bioreactor, however, the nature of convective effect on the photosynthesis has not been fully understood. The purpose of this study concerns the nature of photosynthetic rate in a well-defined hydrodynamic shear flow of Spirulina platensis suspension, generated in a double rotating coaxial cylinders. The double rotating coaxial cylinders was installed in the incubator chamber with the controlled illumination intensity and temperature. Two kind of experiments, short and long term experiments, were performed to evaluate the direct effect of shear flow on the photosynthetic rate. The short term experiment indicates that the simple shear flow enables to augment the photosynthesis of Spirulina suspension and simultaneously causes the cell destruction due to the excessive shear stress. The long term experiment for 100 hours reveals that the growth rate and the morphology of Spirulina is sensitive to the external fluid mechanical stimulus. The long term application of mechanical stress on the algae may result in the adaptation of the photosynthetic function and morphology.

Bioreactors↗