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At least 235 records · Page 13Linked to original sources
PubMed2006

Speciation of aqueous methylmercury influences uptake by a freshwater alga (Selenastrum capricornutum).

Uptake of methylmercury (MeHg) by the alga Selenastrum capricornutum was measured in freshwater batch culture bioassays. The concentration of MeHg in the alga increased rapidly (within 15 min), reached a maximum by 6 h, and then declined because of growth dilution. The alga's rapid growth rate (doubling time, approximately 10 h) contributed to the importance of growth dilution. Conditional first-order rate constants were calculated for uptake (k1 = 6.95 x 10(-9) L/cell/h) and growth (kG = 0.07/h). A competitive synthetic ligand, disodium ethylenediaminetetra-acetate, formed strong complexes with MeHg and reduced MeHg uptake, consistent with the biotic ligand model. A conditional equilibrium formation constant (K) for the MeHg-algae complex was estimated to be approximately 10(16) and was used to model the influence of natural ligands on MeHg bioavailability. Model results suggested MeHg would be most bioavailable at concentrations of dissolved organic matter (DOM) less than 10 mg/L and increasingly unavailable at higher DOM concentrations for the specific humic acid modeled. Similarly, at molar concentrations of sulfide (and, possibly, metal-sulfide clusters) equal to approximately half the MeHg concentration, MeHg was predicted to be unavailable to algae because of the formation of strong 2:1 MeHg-sulfide complexes.

Biological Assay↗
PubMed1981

Hydra viridis: transfer of metabolites between Hydra and symbiotic algae.

"Back transfer" of metabolites from food to endosymbiotic algae in the digestive cells of Hydra viridis was demonstrated. Brine shrimp nauplii labeled with tritiated precursors of protein and nucleic acids (DNA and RNA) were fed to light and dark grown hydras. The fate of the label after a single feeding with radioactive material in hydra and algal fractions was followed by scintillation counting and autoradiographic techniques. Labeled thymidine was incorporated into DNA in both light- and dark-grown hydras. Although the symbiosis persists indefinitely in hydras in darkness (7-10 days) the number of algae per cell is reduced. Tritiated orotic acid and tritiated uridine, RNA precursors, were incorporated into peptides and proteins, and to a lesser extent into simple sugars, oligosaccharides, and oligonucleotides in hydra and algal fractions. Thus the metabolites of the brine shrimp food are available to both partners. A decrease over time in label introduced as 3H-orotic acid and 3H-uridine and incorporated into hydra RNA is compensated for by an increase in label in the algae, implying competition for constant quantities of metabolites from the single feeding. Although food availability, light, number of algae per cell, and other factors influence the quantity and rate of nutrient transfer between the partners, in both light and dark grown hydras the amount of "back transfer" of metabolites to the symbiotic algae is impressive.

Animals↗
PubMed2005

Red algae respond to waves: morphological and mechanical variation in Mastocarpus papillatus along a gradient of force.

Intertidal algae are exposed to the potentially severe drag forces generated by crashing waves, and several species of brown algae respond, in part, by varying the strength of their stipe material. In contrast, previous measurements have suggested that the material strength of red algae is constant across wave exposures. Here, we reexamine the responses to drag of the intertidal red alga Mastocarpus papillatus Kutzing. By measuring individuals at multiple sites along a known force gradient, we discern responses overlooked by previous methods, which compared groups of individuals between "exposed" and "protected" sites. This improved resolution reveals that material strength and stipe cross-sectional area are both positively correlated with drag, suggesting that individual blades or populations can adjust either or both of these parameters in response to their mechanical environment. The combined effect of this variation is a stipe breaking force that is positively correlated with locally imposed drag. Owing to this response to drag, the estimated wave-imposed limit to thallus size in M. papillatus is larger than previously predicted and larger than sizes observed in the field, indicating that factors other than wave force alone constrain the size of this alga on wave-swept shores.

California↗
PubMed2005

Picoeucaryot alga infecting blue mussel Mytilus edulis in southern Norway.

During summer 2001, blue mussels Mytilus edulis with abnormal shell growth were collected near Kragerø, southern Norway. The mussels had green spots in their mantle tissues, mainly posteriorly and ventrally, and in the adductor muscle. Mussels from 4 sites had a prevalence of green spots varying from 2 to 71% that correlated well with shell deformities. Histological examination revealed the presence of round or ovoid algae, 0.9 to 1.5 x 1.2 to 2.4 microm, free within haemocytes and in the lesions, characterised by an inflammatory response and the presence of cellular debris. The alga contain a relatively large nucleus, 1 chloroplast and 1 mitochondrion. Size and morphology suggest that the alga might be a picoeucaryot green alga. Infection of mussel tissues appears to start in the posterior mantle edge, near the siphons, and spread anterior-ventrally in the mantle connective and storage tissues-occasionally spots were also found in the gonad follicles. Large infected areas were also observed in sinuses within the adductor muscle. Only mussels that were 3 yr old or more were infected. Deformations apparently resulted from years of continuous shell formation by a contracted, partly deformed mantle. Most deformed mussels had eroded shells, allowing some light penetration through the exposed, thin nacre. Young, thin-shelled mussels were not infected. The present work suggests that the alga has, at least partially, a parasitic relationship with the mussels, and is associated with pathological alterations in mussel tissues.

Age Factors↗
PubMed1999

[Effect of an algae extract and several plant growth regulators on the nutritional value of potato (Solanum tuberosum L. var. gigant)].

Four commercial plant-growth (Biofol, Biozyme, Cytokin and Activol) and an extract from algae (AlgaEnzims) were applied at commercial doses in potatoes (S. tuberosum L. var. gigant) with and objective to evaluate its effect on nutritional value (dry-matter, water content, ashes, fat, protein, carbohydrates and assimilable fiber). These parameters were analyzed according to the Official Methods of Analysis (AOAC). The experimental design was in Random Blocks with 8 treatments and 4 replications with 32 lots in total. The statistical analysis was after Random Blocks for all bromatological analyses. The treatment algae in soil gave the highest ash content (6.20). Algae in soil (9.30), algae on foliage (8.90) and Cytokin (8.70) gave the highest values in protein as compared with test (6.20). Carbohydrate content was highest in Biofol (88.21), assimilable fiber was higher in algae in soil and on foliage (5.84) and lowest with Biofol (1.67). Highest fat content in the tuber was obtained with Biozyme and Cytokin and highest protein content with AlgaEnzims. With Activol the highest tuber production is obtained.

Crops, Agricultural↗
PubMedDate not supplied

[The cultivation of Vibrio cholerae with green algae in an experiment].

Relationships between Vibrio cholerae of different origin and some serogroups with green algae Scenedesmus quadricauda in mineral medium at two temperatures have been experimentally studied. Differences in the relationships of various strains with green algae under the above-mentioned experimental conditions have been established. The study has shown that a decrease in the concentration and the death of vct+ and vct- vibrios of all strains under study occur in the linear phase of the development of algae. 3 V. cholerae strains, serogroups O139 (vct+) and O50 (vct-), have been shown to be capable of survival under the conditions mix cultivation with algae for 50-100 days. The perish of green algae is supposed to increase the survival time and multiplication of V. cholerae under experimental conditions.

Chlorophyta↗
PubMedDate not supplied

[Effect of blue-green alga (Cyanobacteria) and their exometabolites on formation of resting forms and variability of Yersinia pseudotuberculosis].

Research, carried out with the use of bacteriological methods and polymerase chain reaction, revealed that the transformation of Y. pseudotuberculosis, associated with blue-green algae Anabaena variabilis, into resting (noncultivable) forms took shorter time than in soil extract containing no algae. The exometabolites of "old" cultures of these algae sharply accelerated the formation of resting Y. pseudotuberculosis forms. The influence of the algae and the products of their metabolism was manifested far more intensively at 22 degrees C than at 4 degrees C. After passage through infusoria resting Y. pseudotuberculosis forms, preserved in the mucous covering of cyanobacteria, partially reverted into vegetative forms, capable of growing on solid culture media. The revertants essentially differed from the initial vegetative forms by having lower enzymatic activity, agglutinability and cytopathogenicity, as well as by the loss of plasmid p45. The probable role of blue-green algae, widely spread in soils and water reservoirs, in the processes of reversible transformation of Y. pseudotuberculosis vegetative and resting forms, closely connected with seasonal changes of temperature conditions.

Biological Factors↗
PubMed2002

[Marine algae of Baja California Sur, Mexico: nutritional value].

The Baja California Peninsula is one of the richest regions of seaweed resources in México. The objective of this study was to determine the chemical composition of some marine algae species of Baja California Sur, with an economical potential due to their abundance and distribution, and to promote their use as food for human consumption and animal feeding. The algae studied were Green (Ulva spp., Enteromorpha intestinalis, Caulerpa sertularoides, Bryopsis hypnoides), Red (Laurencia johnstonii, Spyridia filamentosa, Hypnea valentiae) and Brown (Sargassum herporizum, S. sinicola, Padina durvillaei, Hydroclathrus clathrathus, Colpomenia sinuosa). The algae were dried and ground before analysis. In general, the results showed that algae had a protein level less than 11%, except L. johnstonii with 18% and low energy content. The ether extract content was lower than 1%. However, the algae were a good source of carbohydrates and inorganic matter.

Animals↗
PubMed2003

[SR-XRF analysis of characteristics of heavy element concentration in qingdao algae and application to monitoring oceanic pollution].

Quantitative and qualitative analysis of the heavy element concentration characteristics of 14 specimens of 9 kinds of Qingdao algae by synchrotron radiation X-ray fluorescence (SR-XRF) are presented. Results show that various algae are quite different in element concentration. Some algae reveal super concentration ability, such as Sargassum pallidum for As and Sr, Symphyocladia latiuscula for Br and Laminaria japonica for I. Changes in the ratio of peak intensities of Mn and Fe in XRF spectrum reflect on the antagonism between elements in algae, relatively to the environment pollution. The minimum detection limit (MDL) of standard specimen, Antarctic mosses, was measured. Quantitative analysis and comparison of 10 specimens of 5 kind algae gathered from the same zone of Qingdao near-sea in 1985 and in 1999 were done. The contents of Mn, Fe, Zn, As, Br and Pb increased in 1999, in which, As in Sargassum pallidum increased 155% and Pb in Codium fragil increased 120%. The results indicated that the pollution in the near-sea of Qingdao is currently tending toward severity.

Arsenic↗
PubMed1994

Studies on marine algae for haemagglutinic activity.

Lectins (agglutinins) are important in medical and immunological applications. Phytohaemagglutinins have been found useful in blood banking. Keeping in view of these facts, the marine algae found at Karachi coastal region have been screened for agglutinic activity by using human erythrocytes of A, B, AB and 0 group. Altogether 53 algal samples were collected and subjected to extraction, fractionation serial dilution and titre determinations. The total marine algae screened for haemagglutinic activity were 44 out of these 14, 13 and 17 belonged to Chlorophyta, Phaeophyta, and Rhodophyta respectively. Among these three groups the Rhodophyta showed the highest number of lytic activity. The green marine alga Valoniopsis pachynema showed a titre value between 2(2) and 2(3), which is statistically significant. In case of brown marine algae Colpomenia sinuosa was found to be active (titre 2(3)), while Dictyota dichotoma, D. indica and Iyengaria stellata, furnished week titre value as 2(2). The red marine algae screened were 17, out of these 4 spp. showed significant activity (titre 2(3)), and these are Gelidium usmanghani, Gracilaria foliifera Hypnea pannosa and Hynea valentiae. While Scinaia fascicularis, Scinaia indica and Champia parvula were found to be weak in their onset on human erythrocytes. The results obtained were quite in agreement with those reported in the literature.

Journal Article↗
PubMed2006

[Characteristics of heavy metals enrichment in algae ano its application prospects].

Using algae to bio-remedy heavy metals-contaminated waters has become an available and practical approach for environmental restoration. Because of its special cell wall structure, high capacity of heavy metal-enrichment, and easy to desorption, algae has been considered as an ideal biological adsorbent. This paper briefly introduced the structural and metabolic characteristics adapted for heavy metals enrichment of algae, including functional groups on cell wall, extracellular products, and intracellular heavy metals-chelating proteins, discussed the enrichment capability of living, dead and immobilized algae as well as the simple and convenient ways for desorption, and analyzed the advantages and disadvantages of using algae for bioremediation of polluted water, and its application prospects.

Biodegradation, Environmental↗
PubMed2006

[Study on evaluative function model of algae blooms in the representative valleys along Three-Gorges area].

Algal will turn abio-phosphate and ADP (Adenosine biphosphate) into ATP (Adenosine Triphosphate) for storing energy under enough sunlight. As environment conditions change, there will be a reversible process that ATP turns into ADP in order to release energy. Based on local monitoring data from representative valleys along the Three-Gorges valley during algae blooms, the activation energy deltaE of green alga photophosphorylation, the effective energy delta e and the integrated nutritional index TLI(sigma) in these water areas under different hydrological conditions are studied, and then the algae blooms evaluative Function F which has three parameters deltaE, delta e and TLI(sigma) has been constructed. Based on the impact degree of inner factors and environmental factors described above to algae blooms, correlative weight coefficient of deltaE, delta e and TLI(sigma) were introduced as a1 = 0.3, a2 = 0.3 and a3 = 0.4 respectively. Computing results and local monitoring data indicate that F is more reasonable, persuasible and generalizable than a single TLI(sigma) to predicate algae blooms or eutrophication in water environment.

China↗
PubMedDate not supplied

[Functional components in fish and algae oils].

An important area of the development of new functional foods is facussed on finding or applying food components which favour achieving a healthier lipid profile in the organism. The objective of this work was to carry out the characterisation of the lipid fraction of two oils, fish oil and algae oil, to evaluate their potential use as functional ingredients, in relation to the high molecular weight fatty acid content and the presence of sterols and other components of the unsaponificable fraction. Both oils showed a lipid fraction rich in high molecular weight polyunsaturated omega-3 fatty acids, containing a 33.75% in the fish oil and a 43.97% in the algae oil. Eicosapentaenoic acid was the major fatty acid in fish oil, whereas docosahexaenoic was the most abundant fatty acid in algae oil. The omega-6/omega-3 ratio was lower than 0.4 in both oils. In the unsaponificable fraction, algae oil had a Mold lower cholesterol content and a higher proportion of squalene than fish oil. The phytosterol content was significantly higher in the algae oil.

Eukaryota↗
PubMed1975

[Hydrocarbons of the spiruline algae: nature, metabolism of heptadecane by rats and swine].

Hydrocarbons represent about half of the insaponifiable fraction of spirulina algae (0.1 to 0.3 p. 100 of the dry alga); n-heptadecane is the major component (65 p. 100). The retention of this paraffin has been measured in animals receiving these algae as the main or partial protein source. Rats fed with a diet containing 280 ppm n-heptadecane (25 p. 100 alga meal) from weaning show an accumulation of this hydrocarbon in the carcass the retention levels off after 4 months and seems related to the lipid content; preferential fixation occurs in adipose tissue. Sows receiving a diet with 52 ppm heptadecane (5p. 100 alga meal) during growth, pregnancy and lactation retain comparatively much less hydrocarbon; nevertheless n-heptadecane is excreted in the milk.

Adipose Tissue↗
PubMed2001

Toxicant interactions with food algae: a missing link between laboratory and field effects?

Algae fed to invertebrate subjects of chronic toxicity testing are cultured without exposure to test substances. This approach may reduce the ability of bioassays to predict field effects because it assumes that bioconcentration is the only important uptake route, and that an interaction between toxicant and algae does not occur or is not relevant to the effect of the toxicant on test animals. The research presented in this paper focuses on the effects of a bleached kraft mill effluent (BKME) on algae used as food for test animals and the possible consequences of this exposure to bioassay results. The experiment consisted of exposing cultures of a pennate diatom, Navicula, to a range (0-7%) of BKME concentrations for 15 days. Final biomass (measured as chlorophyll a and ash free dry mass) was significantly greater in cultures exposed to 5% and 7% BKME. The carbon-to-nitrogen ratio was significantly higher in diatom cultures exposed to 7% BKME, and total lipid content ranged from 11.7% in the control to 15.8% in the 7% treatment. BKME exposure also increased bacterial content and altered the elemental composition (particularly strontium, barium, iron, and cobalt) of Navicula relative to control cultures. Because changes in food abundance and food quality (e.g., dietary lipids, carbohydrates, proteins) are known to modify toxicity and because contaminant uptake can occur through ingestion, exposing algal food supplies to toxicants would allow chronic bioassays to better simulate field conditions. This approach would be of value in situations where bioassays are intended to predict field effects rather than to compare the toxic potential of effluent samples. Although culturing food algae under exposure to contaminants poses methodological challenges, this approach may serve to enhance the predictive ability of chronic bioassays.

Animals↗
PubMed2006

Photochemoprevention of UVB-induced skin carcinogenesis in SKH-1 mice by brown algae polyphenols.

Chronic exposure of the skin to ultraviolet B (UVB) radiation induces oxidative stress, which plays a crucial role in the induction of skin cancer. In this study, the effect of dietary feeding and topical application of brown algae polyphenols on UVB radiation-induced skin carcinogenesis in SKH-1 mice was investigated. SKH-1 hairless mice were randomly divided into 9 groups, including control, UVB control and treatment groups. They were treated orally (0.1% and 0.5% with AIN-76 diet, w/w) and topically (3 and 6 mg/0.2 ml of vehicle) with brown algae polyphenols and irradiated with UVB for 26 weeks. Dietary feeding (0.1% and 0.5%) of brown algae polyphenols significantly reduced tumor multiplicity (45% and 56%) and tumor volume (54% and 65%), and topical administration (3 and 6 mg) significantly decreased tumor multiplicity (60% and 46%) and tumor volume (66% and 57%), respectively, per tumor-bearing mouse. Dietary feeding and topical administration of the polyphenols also inhibited tumor incidence by 6% and 21%, respectively, but the results were not significant. Dietary and topical administration of the polyphenols markedly inhibited cyclooxygenase-2 activity and cell proliferation. These observations show that brown algae polyphenols have an antiphotocarcinogenic effect which may be associated with the prevention of UVB-induced oxidative stress, inflammation, and cell proliferation in the skin.

Administration, Cutaneous↗
PubMed2004

Light-emitting diodes for the illumination of algae in ecotoxicity testing.

Ecotoxic effects of chemicals, preparations, and environmental samples are routinely quantified in standardized algae growth inhibition tests using microalgae like Desmodesmus subspicatus. The intention of this investigation was to prove the suitability of light-emitting diodes (LEDs) as an alternative to tubular discharge lamps in algae growth inhibition tests. This was approached by demonstrating that growth of algae was similar with both illuminating devices. Growth factors of growth controls were determined using LEDs. Growth curves of different light intensities of LEDs were compared with those of tubular discharge lamps. By testing certain chemicals with both illumination methods comparable results for E(r)C50 values were obtained. It could be shown that small-scale construction of incubators using LEDs is possible and could be advantageous, especially for the illumination of algae in 96-well microplate growth inhibition assays.

Biological Assay↗
PubMed1994

High substrate specificity factor ribulose bisphosphate carboxylase/oxygenase from eukaryotic marine algae and properties of recombinant cyanobacterial RubiSCO containing "algal" residue modifications.

Marine algae play an important role in removing carbon dioxide from the atmosphere. In this investigation, we have determined the substrate specificity factor of ribulose 1,5-bisphosphate carboxylase/oxygenase from several marine chromophytic and rhodophytic algae. The enzymes were purified to homogeneity and all possessed significantly higher substrate specificity factors than the enzymes from terrestrial plants, green algae, or bacteria. There are substantial differences in the sequence in a helix 6 of the large subunit of these enzymes, which is intriguing since residues of this region had been previously shown to influence the ability of ribulose bisphosphate carboxylase to discriminate between CO2 and O2, presumably by influencing the adjacent flexible loop 6 region. Sequence divergence at this and other key regions might contribute to the substantial differences in the substrate specificity factor of the chromophyte/rhodophyte enzyme. Initial studies on probing the basis for the high substrate specificity factor employed single amino acid substitutions in the recombinant cyanobacterial ribulose bisphosphate carboxylase. Residues in the vicinity of loop 6 were changed to reflect the corresponding residues in the chromophyte/rhodophyte large subunit. Some changes in the substrate specificity factor were noted, as were alterations in other important kinetic parameters. Since marine algae show little evidence of photorespiratory metabolism, the high substrate specificity of ribulose bisphosphate carboxylase is consistent with the physiology of these organisms. The results of this study provide further evidence that the properties of this enzyme may evolve or change according to the environment in which the host organism is found.

Amino Acid Sequence↗