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PubMed1989

New natural polysaccharides with potent antithrombic activity: fucans from brown algae.

Fucans extracted from brown algae exhibit anticoagulant properties, as demonstrated by coagulation assays and kinetic study of the inactivation of thrombin in the presence of antithrombin III. These derivatives exert a direct antithrombic activity by an antithrombin III-independent pathway. Besides, their anticoagulant activity is not mediated by a potency to inhibit factor Xa. Relatively low-molecular-mass fractions (50,000 Daltons) prepared by chromatographic fractionation of the crude fucans also exhibit anticoagulant activity. They may prove useful as anticoagulant drugs.

Antithrombin III↗
PubMed1988

H blood group detection by the L-fucose binding lectin of the green marine alga Ulva lactuca.

Extracts of the green marine alga Ulva lactuca collected along the seashore of Tel-Aviv exhibit hemagglutinating activity towards papain-treated human erythrocytes. This hemagglutinating activity was shown to be inhibited by L-fucose and EDTA, and to be relatively resistant to heating at 60 degrees C, while sensitive to low pH. Like the lectin of Ulex europeus, the Ulva lectin exhibits blood group H specificity. It agglutinates most strongly erythrocytes of blood group 0(H) followed by B greater than A greater than AB. A2 and A2B erythrocytes are agglutinated by it considerably more strongly than A1 and A1B respectively. Bombay 0(hh) type erythrocytes are almost non-reactive. The lectin can be stored at -20 degrees C for years.

ABO Blood-Group System↗
PubMed1987

Influence of cypermethrin and fenvalerate on a green alga and three cyanobacteria isolated from soil.

The effects of two pyrethroid insecticides, cypermethrin and fenvalerate, on a green alga (Scenedesmus bijugatus) and three species of cyanobacteria (Synechococcus elongatus, Nostoc linckia, and Phormidium tenue), all isolated from a black cotton soil, were studied using either cell number or chlorophyll a as toxicity criterion. All the four species were either unaffected or stimulated at 5 micrograms ml-1. Of the two insecticides, cypermethrin, at 10 to 50 micrograms ml-1, inhibited S. bijugatus while these concentrations stimulated or only slightly inhibited the growth of S. elongatus. There was a significant inhibition in the growth of S. bijugatus and stimulation in S. elongatus with 10 to 50 micrograms ml-1 fenvalerate. The growth of N. linckia was enhanced by both insecticides while P. tenue was significantly affected.

Chlorophyll↗
PubMed1994

Effect of atrazine herbicide on growth, photosynthesis, protein synthesis, and fatty acid composition in the unicellular green alga Chlorella kessleri.

Sublethal atrazine concentrations induced a general inhibition on growth, photosynthesis, and dark respiration in the green alga Chlorella kessleri. 14C-protein hydrolysate indicated a maximum incorporation level by 5 microM atrazine after 48 hr. Progressive reduction in protein synthesis was associated with increasing herbicide concentration at all experimental periods. The herbicide had preferential effect on the associated fatty acid composition of total and phospholipids. After 24 and 48 hr the herbicide stimulated fatty acids synthesis at concentrations where photosynthesis was inhibited. Meanwhile, stearic and miristic acids disappeared at 15 microM after 24 hr and the total polyunsaturated fatty acids were not affected after 48 hr. Fatty acid synthesis was sensitive to treatment at 72 hr by 5 and 10 microM atrazine, whereas the total saturated fatty acids were completely inhibited.

Atrazine↗
PubMed1979

The mutagenicity of natural products from marine algae.

5 polyhalogenated hydrocarbon natural products isolated from the marine red alga Plocamium spp. were tested for mutagenicity in the Ames reversion assay. All 5 of the compounds induced revertants in Salmonella typhimurium strains TA100 and TA1535, indicating the mutational events involved base substitutions. One of the compounds, designated cross-conjugated ketone, was shown to be almost 200 times more effective as a mutagen than was ethyl methanesulfonate.

Hydrocarbons, Halogenated↗
PubMed1992

Extended secondary structure as a basis of increased RNA stability in a thermophilic alga Cyanidium caldarium.

To identify important structural features in the intergenic sequences of ribosomal DNAs, the nucleotide sequence of the 18-25S rRNA intergenic region was determined in a thermophilic alga, Cyanidium caldarium. Although the mature 5.8S RNA is more stable to thermal denaturation, sequence comparisons reveal a longer molecule with a surprisingly low G/C nucleotide composition. Estimates of the structure further indicate that, unlike other thermophilic examples, thermostability in this organism results, at least in part, from an extended secondary structure.

Base Composition↗
PubMed1993

An open reading frame in the Rhodospirillum rubrum plasmid, pKY1, similar to algA, encoding the bifunctional enzyme phosphomannose isomerase-guanosine diphospho-D-mannose pyrophosphorylase (PMI-GMP).

The nucleotide sequence of a BglII fragment (3188 bp) from the plasmid pKY1 of Rhodospirillum rubrum was determined. A significant similarity was found between the amino acid sequences deduced from the nucleotide sequence of BglII fragment with that of algA, encoding the bifunctional enzyme with both the activities of phosphomannose isomerase and guanosine diphospho-D-mannose pyrophosphorylase of Pseudomonas aeruginosa.

Amino Acid Sequence↗
PubMed1994

Isolation of multiple dimeric forms of phosphoribulokinase from an alga and a higher plant.

Dimeric phosphoribulokinase from either spinach (Spinacia oleracea) leaf or from the green alga, Scenedesmus obliquus can be separated into three distinct forms by hydrophobic interaction chromatography. Variation of the redox conditions prior to and during chromatography resulted in specific forms of phosphoribulokinase being eluted. It is suggested that three dimeric forms of phosphoribulokinase differ in the extent of disulfide bond formation between Cys-16 and Cys-55 in each of the two subunits. Phosphoribulokinase-3, isolated under the most oxidising conditions and exhibiting unusual kinetics, has properties consistent with those expected of an oxidised form of the enzyme in which Cys-16 and Cys-55 are completely oxidised to form a disulfide bond in each subunit. Phosphoribulokinase-1 is the completely reduced form predominating following incubation of extracts with dithiothreitol. Phosphoribulokinase-2, the intermediate species in which only one subunit possesses the disulfide, predominates only when extracts, previously reduced by high concentrations of 2-mercaptoethanol, are allowed to stand overnight in the presence of air prior to chromatography.

Chlorophyta↗
PubMed1991

Polyphosphate metabolism in the alga Dunaliella salina studied by 31P-NMR.

Polyphosphate synthesis and the state of the intracellular polyphosphates in the unicellular green alga Dunaliella salina were studied using in vivo 31P-NMR spectroscopy. By perfusing phosphate-depleted algal cells trapped inside agarose beads with orthophosphate (Pi) containing medium, we were able to follow the process of polyphosphate synthesis in whole, living cells. The results suggest that, in Dunaliella, low molecular weight, probably cyclic, polyphosphate intermediates are synthesized from Pi, and are then condensed to high molecular weight polymers. Studies of the intracellular organization of the polyphosphates by electron microscopy and solid-state NMR techniques indicate that most of these polymers are stored in the cell in a soluble form, and not in solid-like structures.

Chlorophyta↗
PubMed1987

The effects of crude and fuel oils on the growth, chlorophyll 'a' content and dry matter production of a green alga Scenedesmus quadricauda (Turp.) bréb.

The growth of Scenedesmus quadricauda algae in a batch culture was examined in the presence of crude oil and fuel oil, added to the cultivation medium in the form of a water-soluble fraction (WSF), water extract (WE) and oil-water dispersion (OWD). On applying various concentrations of oils, a decrease in the number of cells, dry matter and chlorophyll 'a' production, with respect to the cell population, was observed. The extent of this decrease depended on the kind and concentration of the soluble and dispersed hydrocarbon fractions and on the proportions in which these occurred in the culture medium. On the other hand, the water extracts of both oils stimulated dry mass and chlorophyll 'a' content with respect to a single cell. This effect was accompanied by increased size of the algal cells. The WSF, WE and OWD of fuel oil, prepared from 200, 50 and 1 cm(3) of oil per dm(3) of BBM medium, respectively, had a similar inhibitory effect, which points to the dominant role of oil dispersion in the reduction of algal growth. Chemical analysis of the water extracts of fuel oil revealed the presence of 35 hydrocarbons of various kinds, mainly n-alkanes and polycyclic aromatic hydrocarbons.

Journal Article↗
PubMed1989

Atomic absorption spectrometric determination of inorganic and organic arsenic in some marine benthic algae of the southern atlantic coasts.

Arsenic in the inorganic and organic forms was analyzed in species of marine macro-algae growing in the South Atlantic Ocean. Species of the genera Lessonia, Gigartina, Adenocystis, Leathesia and Colpomenia were investigated. Arsenic accumulation was found in all species studied. Total As content ranged from 5.3 to 56.9 microg As g(-1) and the levels of the inorganic forms ranged from 0.2 to 2.0 microg As g(-1). The complete analytical procedure was validated against a standard reference material (NBS, SRM 1572, citrus leaves) and the value obtained was in good agreement with the certified value. Some commercial seaweed products were also analyzed.

Journal Article↗
PubMed1989

60Co retention by a freshwater planktonic alga Scenedesmus obliquus.

This paper presents the results of various decontamination experiments aimed at evaluating (60)Co retention by Scenedesmus obliquus, and the respective roles played by absorption and adsorption in the contamination of the alga by this radionuclide. The physiological condition of cells is not involved in radiocobalt desorption, which seems to indicate that the phenomenon is of a passive nature. When the precontamination time is extended, the proportion of adsorbed (60)Co decreases, and the final percentage of radionuclide retained increases. These results are confirmed by bringing cells into contact with a strong chelating agent. The elimination of (60)Co in the presence of EDTA undergoes a sharp decrease which is correlated with the increase in the duration of the precontamination phase. The use of a weaker complexing agent, such as NaCl, leads to the hypothesis of there being 2 types of (60)Co receptor on cell membranes.

Journal Article↗
PubMed1990

Bioaccumulation and toxicity of zinc in the green alga, Cladophora glomerata.

The bioaccumulation and toxicity of zinc in Cladophora glomerata from two populations in the River Roding, Essex, UK, were examined in experimental laboratory flowing-water channels. Plants were subjected to zinc concentrations ranging from 0 to 4.0 mg litre(-1) at current velocities of 20-33 cm s(-1) for up to 3 h. Zinc in algal tissue was then quantified and toxicity was assessed by the ability of the alga to grow in a recovery medium after the experimental treatment. There was little difference in zinc bioaccumulation between Cladophora from the site showing mild organic pollution and that from the site subjected to considerable inputs from urban and motorway runoff. Uptake of zinc increased with increasing concentration in the test solution and was linear and proportional up to 0.4 mg litre(-1). Three stages of uptake were identified with the most dramatic accumulation occurring in the first 10 min. Experimental concentration factors ranged from 1.9-5.2 x 10(3), which were in agreement with those previously obtained in the field. Cellular damage was evident in Cladophora subjected to 0.4 mg litre(-1) zinc, and this increased with increasing zinc concentration, thus leading to the conclusion that, at times, the levels of zinc found in the river could be potentially damaging.

Journal Article↗
PubMed1991

The influence of pH on cadmium toxicity to the green alga Stichococcus bacillaris and on the cadmium forms present in the culture medium.

Cadmium toxicity to the green alga Stichococcus bacillaris was investigated in media of pH 3-9. A significant decrease of cadmium toxicity occurred in both the acidic and alkaline ranges of pH. In media of pH 3 and 9, cadmium did not affect the dry mass content substantially. Maximum toxicity of cadmium was noticed at pH 6-7. Voltametric investigations showed a significant effect of pH on electrochemically measured cadmium content in the culture media. Hydrolysis of the medium components and formation of cadmium complexes with OH(-) ions caused a considerable decrease in amounts of electrochemically measured cadmium in the alkaline range of pH.

Journal Article↗
PubMed1995

On the uptake and release of zinc (65Zn) in the growing alga Selenastrum capricornutum Printz.

A Zn- and pH-buffered medium was used to study the accumulation of Zn in batch-cultured algae (Selenastrum capricornutum Printz.). All experiments were carried out using (65)Zn radiotracers, which were measured by gamma-ray spectrometry. Zinc was applied in the presence of nitrilotriacetic acid (NTA), leading to free Zn(2+) concentrations ranging from 4.2 x 10(-11) to 1.6 x 10(-7) mol litre(-1). During the 75-h experiments, the rates of Zn influx and efflux were determined, the latter with full consideration for algal growth rates. Algal growth stopped completely at a free Zn(2+) concentration of 1.6 x 10(-8) mol litre(-1). Initial Zn binding was determined and, based on free Zn(2+) concentrations, presented by the apparent dissociation constant K(diss) and capacity C as 4.6 x 10(-9) mol litre(-1) and 19.8 x 10(6) mol gDW(-1), respectively. The rate constant of Zn efflux could be calculated as a constant 0.021 +/- 0.003 h(-1), irrespective of the Zn concentrations applied. The rates of Zn influx were expressed by the V(max) and K(M) values as 3.3 x 10(-10) mol gDW(-1) s(-1) and 6.3 x 10(-9) mol litre(-1), respectively. These values, which are based on applied free Zn(2+) concentrations, are compatible with the operation of a high-affinity low-concentration carrier mechanism. The results suggest that, under the conditions applied, free Zn(2+) may be the most relevant Zn species for Zn uptake; furthermore, relative growth rate may be regarded as a relatively sensitive signal for Zn stress circumstances.

Journal Article↗
PubMed1987

Food production and gas exchange system using blue-green alga (Spirulina) for CELSS.

In order to reduce the cultivation area required for the growth of higher plants in space adoption of algae, which have a higher photosynthetic ability, seems very suitable for obtaining oxygen and food as a useful source of high quality protein. The preliminary cultivation experiment for determining optimum cultivation conditions and for obtaining the critical design parameters of the cultivator itself has been conducted. Spirulina was cultivated in the 6-liter medium containing sodium hydrogen carbonate solution and a cultivation temperature controlled using a thermostat. Generated oxygen gas was separated using a polypropyrene porous hollow fiber membrane module. Through this experiment, oxygen gas (at a concentration of more than 46%) at a rate of 100-150 ml per minute could be obtained.

Air Conditioning↗
PubMed1992

Theory and experimental results on gravitational effects on monocellular algae.

The orientation of a body which has an anisotropic distribution of mass and which is suspended in water is biased by gravitational torque, so that the center of gravity lies below the center of buoyancy. Many species of unicellular swimming algae are gravitationally oriented in this manner. Their axis of propulsion is essentially fixed within their bodies, so that when the cells swim, they swim upwards. Gravitaxis is an exotaxis, which requires no sensory processing. Nevertheless, gravity affects the lives of these cells both individually and collectively. For single cells, gravity intervenes in the execution and mechanism of sense-dependent taxes, such as phototaxis, it provides for fail-safe locomotion toward the upper interface of their habitat, the source of light and air, and it may cause up-accumulation. Populations of single cells, swimming in the presence of gravity, are coupled through fluid-mechanical interactions which cause spatial and temporal patterns of fluid convection and cell concentration. These patterns modify the cell's environmental interactions, by facilitating downward migrations of cell populations, by mixing the embedding fluid and its contents, and by providing a collective mechanism for controlling light intensity at the individual cell level. Summarizing, gravity modulates the interaction of algal cells with each other and with their environment.

Animals↗
PubMed1996

Energetic metabolism response in algae and higher plant species from simulation experiments with the clinostat.

Adenylate state is acknowledged to be among the most convenient approaches in the study of physiological changes in plant cells under simulation of altered gravity condition with the clinostat. Adenylate levels and the ATP/ADP ratio in cytoplasmic and mitochondrial extracts of cultivated cells of Haplopappus gracilis and algae cells of Chlorella vulgaris under initial stages of the fast-rotating and slow-rotating clinorotation, as well as the long-term clinorotation, have been investigated. For analysis of ATP and ADP levels in the plant cells under the clinorotation, we applied a high-sensitive bioluminescence method using the luciferase and piruvate kinase enzyme systems. It has been shown that the adenylate ratio is already increased during at the start of clinorotation with the different speed of rotation in the biological material tested. The considerable changes in mitochondrial ultrastructure of Chlorella cells, as well as the rising ATP level and dropping of the ATP/ADP ratio appear after long-duration clinorotation if compared to control material. It is probably connected with the distinctions in ATP-synthetase functioning in mitochondria of the cells under the clinorotation conditions.

Adenosine Diphosphate↗