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PubMed2004

Subcellular accumulation of polychlorinated biphenyls in the green alga Chlamydomonas reinhardtii.

In this study, the subcellular accumulation of 13 polychlorinated biphenyl (PCB) congeners was investigated in the green alga Chlamydomonas reinhardtii. Two main arguments pertaining to the mechanism of bioaccumulation of persistent bioaccumulative toxic chemicals (PBTs) in phytoplankton were evaluated, including the controversy of whether the limitation of uptake of ultra-hydrophobic pollutants is kinetic or due to a physical barrier presented by the membrane that prevents transfer into the internal parts of the cell, and second, the role of surface adsorption for the bioaccumulation process. The first argument was addressed by studying the time-dependent subcellular uptake of PCBs into thylakoids (photosynthetic membranes) as representative internal membranes. The second issue was addressed by investigating the role of the algal cell wall as a potential extracellular sorbate. Accumulation of PCBs in thylakoids was found to be limited kinetically and slow compared to total accumulation in the alga. Super-hydrophobic PCBs with Kow > 6 were not restricted from entering the cell. Sorption to the cell wall was found to be less than 10% and insignificant compared to total bioaccumulation in C. reinhardtii. To our knowledge, this is the first study in which the subcellular uptake of a class of PBTs was investigated directly. The results offer a mechanistic framework for improving kinetic modeling of PBT bioaccumulation in phytoplankton.

Adsorption↗
PubMed2005

Bioavailability models for predicting acute and chronic toxicity of zinc to algae, daphnids, and fish in natural surface waters.

Bioavailability models predicting acute and/or chronic zinc toxicity to a green alga (Pseudokirchneriella subcapitata), a crustacean (Daphnia magna), and a fish (Oncorhynchus mykiss) were evaluated in a series of experiments with spiked natural surface waters. The eight selected freshwater samples had varying levels of bioavailability modifying parameters: pH (5.7-8.4), dissolved organic carbon (DOC, 2.48-22.9 mg/L), Ca (1.5-80 mg/L), Mg (0.79-18 mg/L), and Na (3.8-120 mg/L). In those waters, chronic zinc toxicity (expressed as 10% effective concentrations [EC10]) varied up to 20-fold for the alga (72-h EC10 from 27.3 to 563 microg Zn/L), and approximately sixfold for the crustacean (21-d EC10 from 59.2 to 387 microg Zn/L), and fivefold for the fish (30-d LC10, lethal concentration for 10% of the organisms, from 185 to 902 microg Zn/L). For P. subcapitata a refined bioavailability model was developed by linking an empirical equation, which predicts toxicity expressed as free Zn2+ activity as a function of pH, to the geochemical speciation model WHAM/Model V. This model and previously developed acute and/or chronic biotic ligand models for D. magna and 0. mykiss generally predicted most effect concentrations by an error of less than a factor of two. In waters with pH > 8, however, chronic toxicity to D. magna was underestimated by a factor 3 to 4. Based on the results of this validation exercise and earlier research, we determined applicability ranges for pH (6-8) and Ca (5-160 mg/L) in which all three developed models are valid. Within these ranges, all three models may be considered useful tools for taking into account bioavailability in regulatory assessments of zinc.

Animals↗
PubMed2002

Purification and characterization of a new lectin from the red marine alga Hypnea musciformis.

A lectin from the red marine alga Hypnea musciformis (HML) was purified by extraction with 20 mM PBS, precipitation with 70% saturated ammonium sulphate, ion-exchange DEAE-Cellulose chromatography and RP-HPLC. The 9.3 kDa polypeptide agglutinates erythrocytes from various sources and shows oligomerization tendencies under certain MALDI-TOF/MS conditions. Preliminary N-terminal sequencing and biological assays strongly suggest that the HML may belong to a new class of algae lectins.

Animals↗
PubMed1977

Metabolic relationships between green hydra and its symbiotic algae.

1. Hydra that maintain algal symbionts evidenced three modes of metabolism depending upon the nutritional state of the host and the photoperiodic conditions under which the animals were maintained. Animals either fed or fasted but maintained in the dark exhibited an RQ of 0.725 indicating fat metabolism. When they were fed Artemia nauplii and maintained in the light green hydra exhibited a mixed metabolism of carbohydrate and fat which gave an RQ of 0.862. Fasting green hydra, when maintained in the light, showed a pronounced carbohydrate metabolism typified by an RQ of 0.970. 2. Aposymbiotic hydra, whether fed or fasted, exhibited an RQ of 0.725 indicating a high degree of fat metabolism. 3. Symbiotic hydra which were fed and maintained in the light demonstrated a respiration rate of 14.4 microliter/day per hydra, which was 2.5 times greater than animals (symbiotic or aposymbiotic) maintained under any other condition of fasting or photoperiod. It is hypothesized that the enhanced respiration observed in these animals is due to the metabolic activities of the symbiotic algae associated with reproduction and development. 4. Calculations based on respiratory measurements and indirect calorimetry suggest that hydra consume approximately 0.0320 calories per day and that symbiotic algae may supply up to 69% of the host caloric requirements via the translocation of approximately 5 microgram of carbohydrate when the host is fasting and light is provided.

Animals↗
PubMed2001

Synthesis of several light-harvesting complex I polypeptides is blocked by cycloheximide in symbiotic chloroplasts in the sea slug, Elysia chlorotica (Gould): a case for horizontal gene transfer between alga and animal?

The chloroplast symbiosis between the ascoglossan (=Sacoglossa) sea slug Elysia chlorotica and plastids from the chromophytic alga Vaucheria litorea is the longest-lived relationship of its kind known, lasting up to 9 months. During this time, the plastids continue to photosynthesize in the absence of the algal nucleus at rates sufficient to meet the nutritional needs of the slugs. We have previously demonstrated that the synthesis of photosynthetic proteins occurs while the plastids reside within the diverticular cells of the slug. Here, we have identified several of these synthesized proteins as belonging to the nuclear-encoded family of polypeptides known as light-harvesting complex I (LHCI). The synthesis of LHCI is blocked by the cytosolic ribosomal inhibitor cycloheximide and proceeds in the presence of chloramphenicol, a plastid ribosome inhibitor, indicating that the gene encoding LHCI resides in the nuclear DNA of the slug. These results suggest that a horizontal transfer of the LHCI gene from the alga to the slug has taken place.

Animals↗
PubMed2004

Induction of settlement of larvae of the sea urchin Holopneustes purpurascens by histamine from a host alga.

Larvae of the Australian sea urchin Holopneustes purpurascens are induced to settle and metamorphose (termed settlement herein) by a water-soluble compound produced by the red alga Delisea pulchra, the main host plant of new recruits. The settlement cue for H. purpurascens had previously been identified as a floridoside-isethionic acid complex, and this paper presents new evidence correcting that finding. The actual settlement cue produced by D. pulchra was isolated from the polar extract by cation-exchange chromatography and identified as histamine, using one- and two-dimensional nuclear magnetic resonance spectrometry. The chemical identity of the cue was confirmed by gas chromatography-mass spectrometry (GC-MS) and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. Synthetic histamine and histamine at 4.5 microM isolated from D. pulchra both induced rapid settlement in 80%-100% of the larvae of H. purpurascens. Lower concentrations of histamine (0.9-2.3 micro M) induced larval settlement, but this response varied from 0%-90%. The histamine content of two host plants of H. purpurascens--D. pulchra and Ecklonia radiata--and of four other common species was quantified using GC-MS. D. pulchra had the highest histamine content, which is consistent with H. purpurascens recruiting to this species. Histamine was also detected in the seawater surrounding these host algae. This is the first time that a settlement cue has been quantified in the habitat of a marine organism.

Animals↗
PubMed1990

Sequence analysis of the plastid rDNA spacer region of the chlorophyll c-containing alga Cryptomonas phi.

A 0.8 kb AvaI/SmaI fragment of the plastid genome of the chlorophyll c-containing alga Cryptomonas phi encompassing the rRNA spacer region and flanking genes has been cloned and sequenced. The spacer region between the 16S and 23S rRNA genes is 275 base pairs long, one of the shortest yet reported, and it contains uninterrupted genes for tRNA(Ile) and tRNA(Ala) separated by only two base pairs. The coding regions for tRNAs and rRNAs have been compared with those from cyanobacteria, land plants and other algae and the possible evolutionary relationships discussed.

Base Sequence↗
PubMed1982

Cytofluorometric determination of nuclear DNA in living and preserved algae.

Three DNA-localizing fluorochromes used in conjunction with epi (incident) UV illumination were examined for sensitivity and selectivity for the cytofluorometric determination of nuclear DNA in ten species of six algal genera: Mougeotia, Oedogonium, Sirogonium, Spirogyra and Zygnema among the green algae, and the marine red alga Polysiphonia boldii. In comparison with absorption photometry for the determination of nuclear DNA, the cytofluorometric procedure proved to be simpler and considerably more sensitive. Following staining with 4',6-diamidino-2-phenylindole (DAPI), nuclei fluoresce blue-white, the fluorescence intensity of the DNA-DAPI complex being considerably greater than that of the unbound dye molecule. Algal strains stained with 2,5-bis[4'-aminophenyl(1')]-1,3,4-oxadiazole (BAO) also showed brilliant blue-white nuclear fluorescence. Although the BAO schedule requires the use of freshly prepared dye and sulfite water, and careful control of hydrolysis, nuclear fluorescence of the stained specimens does not fade under irradiation of the UV beam as rapidly as it does with certain other fluorochrome procedures. A more useful fluorochrome was the fungal antibiotic mithramycin. Its staining schedule is simple and the bright orange-yellow fluorescence of the nuclei is associated with an exceptional degree of sensitivity and specificity for DNA. Forty-eight-year-old preserved filaments of Spirogyra jatobae, stained with either BAO or mithramycin, exhibited a fluorescence brilliance of nuclear and chloroplast DNA equal to that of fresh specimens of this species. The three schedules, but particularly the one with mithramycin, have proven useful in providing indirect evidence for variation in ploidy level in several of the above algal genera, and in verifying the assumed ploidy level of the gametophyte (haploid) and tetrasporophyte (diploid) of Polysiphonia boldii.

Cell Nucleus↗
PubMed1996

Dietary marine algae promotes efficient deposition of n-3 fatty acids for the production of enriched shell eggs.

Two experiments were conducted to investigate the usefulness of a natural golden marine algae (MA) as a poultry ration supplement for the production of shell eggs rich in n-3 fatty acids (n-3 FA). This MA is unique due to a high concentration of docosahexaenoic acid (DHA; C22:6n-3) and the absence of other n-3 FA normally present in marine oils such as menhaden oil (MO). In the first experiment, 60 24-wk-old Single Comb White Leghorn (SCWL) hens were divided among four dietary treatments, including a typical corn-soybean control (CON); 1.5% MO, supplying 233 mg eicosapentaenoic acid (EPA) and 155 mg DHA per d; 2.4% MA, supplying 200 mg DHA/d; and 4.8% MA, supplying 400 mg DHA/d. A second experiment using 96 56-wk-old SCWL was conducted using the same diets. In both experiments, eggs were collected weekly for 4 wk for determination of egg production parameters and yolk FA content. Each week, yolk samples were extracted, methyl estered, and quantified using gas chromatography. Transient depression in egg and yolk weights were noted early in Experiment 1 in response to dietary 4.8% MA. Although egg and yolk weights were not affected in Experiment 2, egg production was significantly reduced in the 4.8% MA treatment. Egg production was unaffected due to diet or week in Experiment 1. In both experiments, yolk polyunsaturated profiles were significantly influenced by diet. Dietary n-3 FA supplementation significantly increased yolk total N-3 FA with concomitant reductions in yolk n-6 FA. Although hens fed MO were supplied predominantly EPA, the principal yolk FA deposited was DHA. Marine algae also promoted efficient yolk DHA deposition with the highest yolk DHA concentrations attained in eggs from hens fed 4.8% MA. These data indicate that utilization of MA as a direct source of dietary n-3 FA may provide an efficient alternative to current sources of n-3 FA available for the production of poultry products rich in n-3 FA.

Animal Feed↗
PubMed2026

Nucleotide Combination Proportions Across Algae, Monocotyledons and Dicotyledons: Insights into Plant Genome Evolution.

Plant evolution started with unicellular algae, gradually evolving multicellularity and terrestrial colonization. These evolutionary events were accompanied by the interplay of chromosome polyploidization, rearrangement, gene loss, and point mutation. We counted the proportion of nucleotide combinations in the genome sequences of 64 sequenced plants, and analyzed the significant difference in these nucleotide combination proportions among algae, monocotyledons and dicotyledons. The correlation of highly significant different and no significant different nucleotide combinations was analyzed respectively. Nucleotide combinations and their reverse complementary sequence proportions were analyzed in different functional regions of the genome. These results reveal that some nucleotide combinations are subject to strict selection, and these combinations have a higher proportion in the CDS regions and lower proportion in the intergenic regions. Meanwhile, there are some nucleotide combinations that are under less selective pressure, and these combinations have a higher proportion in the intergenic regions and lower proportion in the CDS regions. Cluster analysis based on trinucleotide to octanucleotide combination proportions reveals that plant genome evolution is accompanied by clade-wide differentiation of genome-wide nucleotide composition patterns, in addition to well-documented chromosomal polyploidization, structural rearrangement and gene loss events. We analyzed the changes in the proportion of nucleotide combinations at the genome level in 64 sequenced plants, providing a new idea for studying genome evolution in the plant kingdom.

comparative genomics↗
PubMed1999

Comparative study of the lipids of four dominating species of freshwater plants and algae of the Shulgan river.

The fatty acid and lipid compositions of four dominating species of plants and algae of the Shulgan river--Alliaria petiolata, Rhynchostegium riparioides, Sphaeroplea annulina, and Rhizoclonium hieroglyphicum--were studied. The composition of phospho-, glyco-, and neutral lipids was investigated. A betaine lipid 1(3), 2-diacylglyceryl-(3)-O-4-(N,N,N-trimethyl)homoserine was detected in the polar lipid fraction of the Rhynchostegium riparioides bryophyte. Characteristic distribution of lipids and fatty acids of freshwater plants and algae is discussed in term of various species specificity.

Eukaryota↗
PubMed1978

[Production of vitamin B 12 by a blue-green alga].

In this study, we have been able to demonstrate the production and liberation of vitamin B12 (up to 16.5 pg/ml after 31 days of growth) by a blue green alga. Anabaena flos-aquae, in non-axenic and axenic cultures. This finding has a relevant ecological significance since it shows that, like bacteria, blue green algae may play a role as producers of vitamin B12.

Cyanobacteria↗
PubMed2000

Bacterial dynamics in first year sea ice and underlying seawater of Saroma-ko Lagoon (Sea of Okhotsk, Japan) and resolute passage (High Canadian Arctic): inhibitory effects of ice algae on bacterial dynamics.

The seasonal development of bacterial abundance in first year bottom ice and underlying seawater were studied at Saroma-ko Lagoon in Hokkaido, Japan, and at Resolute Passage in the High Canadian Arctic during the algal bloom in spring 1992. The aim of this study was to evaluate whether the high algal concentrations reached during the bloom of ice algae have inhibitory effects on bacterial dynamics. Bacterial abundance (measured as total cell count and colony-forming units CFU) increased with the increase of the algal biomass up to 500 micrograms Chla.L-1 in both locations. Culturable fraction (measured as the percentage of CFU counts versus the total cell counts) was between 7% and 22% at Saroma-ko, and approximately 0.08% at Resolute Passage. When algal biomass exceeded 500 micrograms of Chla.L-1, both bacterial abundance and culturable fraction decreased significantly. There was a maximum threshold of algal biomass (between 500 and 800 micrograms of Chla.L-1) after which bacterial dynamics become negatively coupled to the algal biomass. These results suggest that bactericidal and/or bacteriostatic compounds from these extremely high algal concentrations could explain the decrease in bacterial abundance and culturability in bottom ice observed after the ice algae bloom.

Arctic Regions↗
PubMed2000

Primary sodium plasma membrane ATPases in salt-tolerant algae: facts and fictions.

For thermodynamic reasons algae growing in media of both high salinity and high alkalinity require active export of sodium. However, experimental evidence for an active Na+-dependent cycle was scarce until recently, in contrast to the situation in marine bacteria (including cyanobacteria), fungi and animals. However, a review of literature reveals that some progress has been made in this respect, recently: data demonstrate that at least in two marine algae, Tetraselmis (Platymonas) viridis and Heterosigma akashiwo (syn. Olisthodiscus luteus), active Na+-export is carried out by means of a plasma membrane localized Na+-pump (apparent molecular mass 100-140 kDa). Biochemical characteristics of this vanadate-sensitive, but ouabain-resistant primary P-type Na+-ATPase are described and compared with the corresponding properties of Na+-ATPase from prokaryotes and animals. Alternative mechanisms for Na+-pumping are discussed.

Adenosine Triphosphate↗
PubMedDate not supplied

[Response of the algae Gymnodinium kovalevskii (Dinophyta) to exposure to synthetic detergents and distillation].

The effects of synthetic detergents and combined effects of synthetic detergents and water freshening on growth characteristics of the alga Gymnodinium kovalevskii (Dinophyta) were studied. Low concentrations of synthetic detergents (0.1 and 1.0 mg/l) stimulated the algal growth. Elevated concentrations inhibited cell division, affected their motility and induced morphological changes. Contamination with synthetic detergents adversely affected the adaptation plasticity of algae with respect to salinity.

Adaptation, Physiological↗
PubMed2000

Thermotropic behaviour of membrane lipids from brown marine alga Laminaria japonica.

Microcalorimetry was used to show that transition-temperature ranges of phospho- and glycolipids of the brown marine alga Laminaria japonica were similar (from -62 to -47 degrees C up to 62-65 degrees C), except for monogalactosyldiacylglycerol, the low-temperature limit of which was shifted to -78 degrees C. As was shown by polarizing microscopy, the low-enthalpy peaks at temperatures of approx. 30-45 degrees C corresponded to isotropic melting of galactolipids and coincided with the high-temperature limit for photosynthetic and mitochondrial activity of the algae. As a whole, a classical interrelation was observed between thermotropic behaviour and the fatty acid unsaturation of lipids.

Acclimatization↗
PubMed2000

[Algae in dam reservoirs used for drinking water production in Morocco].

As part of the study of water quality of dam reservoirs used for drinking-water production, the Water Quality Laboratory of the National Office for Drinking Water in Morocco prepared a micrographic atlas of the main species of planktonic algae found in 22 reservoirs over a period of 25 years. The atlas includes 321 micrographs representing 156 taxons with an indication of the sample location and an enlargement ratio for each micrograph. In some cases, information is also provided on algae associations, algal counts and monthly occurrence.

Colony Count, Microbial↗
PubMed2001

Algae-removal performance of a fluidized-bed biofilm reactor system for lake water treatment.

The algae removal efficiency of a pilot plant--based on a fluidized-bed biofilm reactor system for treating--was investigated. This system does not require back-washing because the fluidized-bed suffers no clogging. Moreover, the system uses dissolved oxygen in the influent water for aerobic biological treatment without the need for additional aeration equipment. This, it is an easy-maintenance, low-energy system for purifying eutrophic lake water. The system was operated continuously at a flow rate of 1500 m3/d for nine months at Tsuchiura Port in Lake Kasumigaura. And concentrations of chlorophyll-a and dissolved oxygen in both the influent and effluent water were continuously monitored. In summer (August to September) when water bloom occurred, the average efficiency of chlorophyll-a removal was 64% at an average influent chlorophyll-a concentration of 137.8 micrograms/L. Over the entire experimental period of nine months, the average daily amount of removed chlorophyll-a was 40.3 g/d at an average influent chlorophyll-a concentration of 89.5 micrograms/L. By analyzing the relationship between the amount of removed chlorophyll-a and the consumption of dissolved oxygen, it was estimated that almost all of the algae trapped in the reactor was biologically degraded.

Biofilms↗