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At least 1,621 records · Page 90Linked to original sources
PubMed2000

Ionic strength effects in biosorption of metals by marine algae.

Biosorption, the passive accumulation of metals by biomass, can be used as a cost-effective process for the treatment of metal polluted industrial effluents. The green alga Ulva fascia and the brown seaweeds Sargassum hemiphyllum, Petalonia fascia, and Colpomenia sinuosa were characterized in terms of their number of binding sites, their charge density and intrinsic proton binding constant (pKa) using pH titrations at different ionic strengths. The determined number of binding sites decreased in the order Petalonia > or = Sargassum > Colpomenia > Ulva. Due to their high number of binding sites Sargassum and Petalonia are most promising for biosorption applications. The decrease of proton binding with increasing ionic strength and pH as well as the increase of Cu and Ni binding with increasing pH and decreasing ionic strength could be described by the Donnan model in conjunction with an ion exchange biosorption isotherm.

Absorption↗
PubMed2001

Anticoagulant properties of a sulfated galactan preparation from a marine green alga, Codium cylindricum.

An anticoagulant was isolated from a marine green alga, Codium cylindricum. The anticoagulant was composed mainly of galactose with a small amount of glucose, and was highly sulfated (13.1% as SO3Na). The anticoagulant properties of the purified anticoagulant were compared with that of heparin by assays of activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) using normal human plasma. The anticoagulant showed similar activities with heparin, however, weaker than heparin. On the other hand, the anticoagulant did not affect PT even at the concentration at which APTT and TT were strongly prolonged. The anticoagulant did not potentiate antithrombin III (AT III) and heparin cofactor II (HC II), thus the anticoagulant mechanism would be different from that of other anticoagulants isolated so far from the genus Codium.

Anticoagulants↗
PubMed2003

Lead and cadmium levels in coastal benthic algae (seaweeds) of Tenerife, Canary Islands.

Lead and cadmium levels of some species of brown-algae (Phaeophyta) from the mesolittoral (intertidal area) of the Island of Tenerife (central-eastern Atlantic) were determined by Atomic Absorption Spectrometry. The quality control was carried out using a standard "CRM 279 Ulva lactuca". The mean, minimum and maximum concentrations were 11.21, 2.090 and 81.795 microg/g/dw; and 1.13, 0.190 and 5.130 microg/g/dw for lead and cadmium, respectively. The fact that samples registering the highest cadmium concentrations were the same as those which showed the highest lead level corresponding to a sampling station nearby an urban water outlet could be relevant.

Atlantic Ocean↗
PubMed2001

Intron-specific RNA binding proteins in the chloroplast of the green alga Chlamydomonas reinhardtii.

Mitochondria and chloroplasts both contain group II introns which are believed to be the ancestors of nuclear spliceosomal introns. We used the mitochondrial group II intron rI1 from the green alga Scenedesmus obliquus for biochemical characterization of intron-specific RNA binding proteins. rI1 is correctly spliced from a chloroplast precursor RNA when integrated into the chloroplast genome of Chlamydomonas reinhardtii. Glycerol gradients revealed the sedimentation profile of transcripts containing intron rI1 in native C. reinhardtii extracts and in deproteinized RNA preparations, thus indicating the association of rI1 containing transcripts with high molecular weight ribonucleoprotein complexes in vivo. Furthermore, the specific binding of a 61 kDa protein and a 31 kDa protein with the conserved domain IV was demonstrated using a set of intron derivatives for in vitro RNA binding experiments. We propose that we have biochemically characterized 'general splicing factors', which enable the successful splicing even of mitochondrial introns in chloroplasts.

Animals↗
PubMed2001

Characterization of a nicotinamide nucleotide transhydrogenase gene from the green alga Acetabularia acetabulum and comparison of its structure with those of the corresponding genes in mouse and Caenorhabditis elegans.

Proton-pumping nicotinamide nucleotide transhydrogenase (Nnt) is a membrane-bound enzyme that catalyzes the reversible reduction of NADP(+) by NADH. This reaction is linked to proton translocation across the membrane. Depending on metabolic conditions, the enzyme may be involved in NADPH generation, e.g., for detoxification of peroxides and/or free radicals and protection from ischemic damage. Nnt exists in most prokaryotes and in animal mitochondria. It is composed of 2-3 subunits in bacteria and of a single polypeptide in mitochondria. An open question is whether Nnt exists in any photosynthetic eukaryotes and if so, to which class it belongs. In the present study it is demonstrated that, by cloning and sequencing cDNA and genomic copies of its NNT gene, an ancient alga, Acetabularia acetabulum (Chlorophyta, Dasycladales), contains a nuclear-encoded Nnt. In contrast to photosynthetic bacteria, this algal Nnt is composed of a single polypeptide of the class found in animal mitochondria. Excluding a poly(A) tail, NNT cDNA from A. acetabulum is 3688 bp long, consists of eight exons and spans 17 kb. The NNT gene from mouse was also characterized. Subsequently, the gene organization of the A. acetabulum NNT was compared to those of the homologous mouse (100 kb and 21 exons) and Caenorhabditis elegans (5.1 kb and 18 exons) genes.

Amino Acid Sequence↗
PubMed2002

Isolation and molecular characterization of the [Fe]-hydrogenase from the unicellular green alga Chlorella fusca.

[Fe]-hydrogenases are redoxenzymes that catalyze the reversible reduction of protons to hydrogen. Hydrogenase activity was observed in a culture of the unicellular green alga Chlorella fusca after an anaerobic incubation, but not in the related species Chlorella vulgaris. Specific polymerase chain reaction (PCR) techniques lead to the isolation of the cDNA and the genomic DNA of a special type of [Fe]-hydrogenase in C. fusca. The functional [Fe]-hydrogenase was purified to homogeneity and its N-terminus was sequenced. The polypeptide sequence shows a high degree of identity with the amino acid sequence deduced from the respective cDNA region. Structural and biochemical analyses indicate that ferredoxin is the main physiological electron donor.

Algal Proteins↗
PubMed2000

A cDNA from the green alga Spermatozopsis similis encodes a protein with homology to the newly discovered Roadblock/LC7 family of dynein-associated proteins.

A clone, designated as B15, was isolated from a cDNA library of the unicellular green alga Spermatozopsis similis and characterised. The deduced amino acid sequence of its open reading frame exhibits high homology to members of the recently discovered roadblock/LC7 protein family (robl/LC7) of dynein-associated proteins. Homologies were highest to a robl/LC7-member from human testis (86%, identity 56%) and to the roadblock protein of Drosophila (88%, identity 52%). Data bank analyses revealed no homologies to known higher plant proteins. B15 is a single copy gene in the genome of Sperm-latozopsis and its transcript was detectable throughout the cell cycle.

Amino Acid Sequence↗
PubMed1999

A group of alpha-1,4-glucan lyases and their genes from the red alga Gracilariopsis lemaneiformis: purification, cloning, and heterologous expression.

We present here the first report of a group of alpha-1,4-glucan lyases (EC 4.2.2.13) and their genes. The lyases produce 1, 5-anhydro-D-fructose from starch and related oligomers and polymers. The enzymes were isolated from the red alga Gracilariopsis lemaneiformis from the Pacific coasts of China and USA, and the Atlantic Coast of Venezuela. Three lyase isozymes (GLq1, GLq2 and GLq3) from the Chinese subspecies, two lyase isozymes (GLs1 and GLs2) from the USA subspecies and one lyase (GLa1) from the Venezuelan subspecies were identified and investigated. GLq1, GLq3, GLs1 and GLa1 were purified and partially sequenced. Based on the amino acid sequences obtained, three lyase genes or their cDNAs (GLq1, GLq2 and GLs1) were cloned and completely sequenced and two other genes (GLq3 and GLs2) were partially sequenced. The coding sequences of the lyase genes GLq1, GLq2 and GLs1 are 3267, 3276 and 3279 bp, encoding lyases of 1088, 1091 and 1092 amino acids, respectively. The deduced molecular masses of the mature lyases from the coding sequences are 117030, 117667 and 117790 Da, respectively, close to those determined by mass spectrometry using purified lyases. The amino acid sequence identity is more than 70% among the six algal lyase isozymes. The algal GLq1 gene was expressed in Pichia pastoris and Aspergillus niger, and the expression product was identical to the wild-type enzyme.

Amino Acid Sequence↗
PubMed1998

Characterization of a chloroplast isoform of serine acetyltransferase from the thermo-acidiphilic red alga Cyanidioschyzon merolae.

We isolated a gene for serine acetyltransferase (SAT), a key enzyme in sulfate assimilation, from the primitive red alga Cyanidioschyzon merolae, an inhabitant of sulfurous hot springs, and designated this gene cmSAT. The N-terminal region of the cmSAT protein has characteristics of a chloroplast targeting peptide. cmSAT protein fused with a 6x histidine tag complemented a SAT deficient Escherichia coli mutant. The protein was purified with its SAT activity, which was inhibited by cysteine, using the high affinity of the histidine tag in an Ni-NTA column. The Km values for acetyl-CoA and l-serine were 0.3 and 0.1 mM, respectively. Southern blotting indicated the existence of other SAT isoforms in C. merolae. A 2.4 kb transcript was always detected when growth was synchronized under a 12-h light/dark cycle. Under these conditions, a 31-kDa protein was always detected on immunoblots, indicating processing of the cmSAT protein and constitutive expression of cmSAT. A 45-kDa protein, thought to be the unprocessed cmSAT protein, was detected in the dark period, from M phase to early G1 phase. No significant change in the level of protein expression was detected under continuous darkness or in a sulfate-deficient medium. Using immunoelectron microscopy, the cmSAT protein was primarily detected in the stroma and a few were detected in the cytoplasm, which indicate that cmSAT protein is transported to and functions in a chloroplast.

Acetyltransferases↗
PubMed2003

Lateralization defects and ciliary dyskinesia: lessons from algae.

Flagella and cilia are two very similar organelles that "beat" to move cells and to propel fluid over tissues. They are highly conserved, being found in organisms ranging from prokaryotes to plant and animal eukaryotes. In humans, cilia are present in almost every organ, and several human conditions involve dysfunctional cilia; for example, lateralization defects, where the positions of organs are reversed, and primary ciliary dyskinesia, a rare condition where patients suffer from recurrent respiratory infections. In this article, we will discuss how information gained from studies on algae has aided research into these human diseases. These studies found a variety of functions that was previously unsuspected, renewing interest in cilia.

Animals↗
PubMed1997

Potent anti-inflammatory activity of pheophytin a derived from edible green alga, Enteromorpha prolifera (Sujiao-nori).

Recently, a chlorophyll-related compound, pheophytin a, has been identified from an edible green alga, Enteromorpha prolifera (Sujiao-nori in Japanese) as a potent suppressive substance against genotoxin-induced umu C gene expression in a tester bacteria (Okai and Higashi-Okai, 1997, J. Sci. Food Agricul. 71, 531-535). In the present study, anti-inflammatory effects of pheophytin a from Enteromorpha prolifera have been analyzed using in vitro and in vivo experiments. 1. Pheophytin a suppressed the production of superoxide anion (O2-) in mouse macrophages induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) using the cytochrome C reduction method. 2. Pheophytin a caused a suppressive effect against formyl-Met-Leu-Phe, (FMLP)-induced chemotaxis of human polymorphonuclear leukocytes (PMNs) in Boyden's chamber experiment. 3. Pheophytin a exhibited a significant suppression against TPA-induced inflammatory reaction such as edema formation in BALB/c mouse ear. These results suggest that pheophytin a from Enteromorpha prolifera has a potent anti-inflammatory activity.

Animals↗
PubMedDate not supplied

Ultrastructure of post-fertilization development in the red alga Scinaia articulata (Galaxauraceae, Nemaliales, Rhodophyta).

The ultrastructure of the carposporophyte and carposporogenesis is described for the red alga Scinaia articulata Setch. After fertilization, the trichogyne disappears, and the pericarp develops to form a thick protective tissue that surrounds the carposporophyte. The hypogynous cell cuts off both one-celled and two-celled sterile branches. Patches of chromatin are frequently observed in evaginations of the nuclear envelope, which appear to produce vesicles in the cytoplasm of the cell of the sterile branch. Large gonimoblast lobes extend from the carpogonium and cleave to form gonimoblast initials. Subsequently, a fusion cell is formed from fusions of the carpogonium, the hypogynous cell and the basal cell of the carpogonial branch. The mature carposporophyte comprises the fusion cell that is connected to the sterile branch cells, gonimoblast cells and carpospores and is surrounded by extensive mucilage. Young carpospores possess a large nucleus and proplastids with a peripheral thylakoid, but they have few dictyosomes and starch granules and are indistinguishable from gonimoblast cells. Subsequently, dictyosomes are formed, which produce vesicles with an electron-dense granule, which indicates an initiation of wall deposition. Thylakoid formation coincides with incipient starch granule deposition. The nuclear envelope produces fibrous vacuoles and concentric membrane bodies. Carpospores are interconnected by pit connections with two cap layers. Dictyosome activity increases, resulting in the production of vesicles, which either continue to deposit wall material or coalesce to form fibrous vacuoles. The final stage of carposporogenesis is characterized by the massive production of cored vesicles from curved dictyosomes. Mature carpospores are uninucleate and contain fully developed chloroplasts, numerous cored vesicles, numerous starch granules and fibrous vacuoles. The mature carpospore is surrounded by a wall layer and a separating layer, but a carposporangial wall is lacking.

Animals↗
PubMed2001

Cadmium(II) removal from aqueous solutions by pre-treated biomass of marine alga Padina sp.

In this study, the adsorption properties of a pre-treated biomass from marine alga Padina sp., a biomass collected from Surin Island, Thailand, for removal of cadmium(II) ions from aqueous solutions was investigated. Batch and column experiments were conducted to determine the adsorption properties of the modified biomass. At a pH of 5, the maximum removal capacity of the biomass is 0.53 mmol/g. The kinetics of cadmium(II) adsorption were fast with 90% of adsorption taking place within 35 min. This study demonstrated that the pre-treated biomass of Padina sp. could be used as an efficient biosorbent for the treatment of cadmium(II)-bearing wastewater streams.

Adsorption↗
PubMed2001

Kinetics of chromium (VI) reduction by a type strain Shewanella alga under different growth conditions.

We conducted kinetic batch experiments to determine the reduction of Chromium(VI) by a type strain of Shewanella alga (BrY-MT) ATCC 55627. Chromium(VI) was reduced to Chromium(III) by BrY-MT grown in three different substrates: BHIB (brain heart infusion broth), TSB (tryptic soy broth), and M9 (minimum broth). Four different Cr(VI) concentrations 4.836, 10.00, 37.125, and 260.00 mg l-1 were reduced at different rates by BrY-MT in both aerobic and anaerobic conditions. BrY-MT grown in BHIB reduced the maximum amount of Cr(VI) followed by TSB and M9. Carbondioxide produced from bacterial respiration varied with and without Cr(VI) under both aerobic and anaerobic conditions. The Cr(VI) reduction data under anaerobic condition was fitted by a monod model to determine the bacterial kinetic parameters. The kinetic parameters determined by fitting the anaerobic experimental data were used to run a forward simulation for experiments conducted under aerobic conditions. The monod model was modified to account for an inhibition parameter for the Cr(VI) experiment at 260 mg l-1. All the parameters varied within a narrow range, and were distinct for different substrates. Our studies show that, successful in situ bioremediation of Cr(VI) is depended on the type of substrates (electron donors) and the concentration of Cr(VI) in geologic medium.

Aerobiosis↗
PubMed2003

Two new growth inhibition tests with the filamentous algae Ceramium strictum and C. tenuicorne (Rhodophyta).

Two growth inhibition tests using the red marine macroalgae Ceramium strictum and the brackish water relative C. tenuicorne have been developed. Besides using phenol as a reference substance, the toxicity of a metal, a flame retardant and a complex effluent water were assayed. The two methods are reliable and repeatable bioassays for salinities between 4 and 30 per thousandth. The coefficients of variation (CV) for toxicity of the reference substance phenol were 15% for the Stereo Microscope Analysis test and between 24 and 51% for the Computer Image Analysis test (n=5). Ceramium spp. are common and important primary producers in temperate coastal waters and are thus relevant as test organisms. Both algae grow well in laboratorial conditions and tests can be performed all year around.

Biological Assay↗
PubMed2001

Trace metals in seagrass, algae and molluscs from an uncontaminated area in the Mediterranean.

The concentrations of Cd, Cr, Cu, Pb and Zn were measured in specimens of four marine organisms--the seagrass Posidonia oceanica (L.) Delile, the brown algae Padina pavonica (L.) Thivy, and the two gastropod molluscs Monodonta turbinata Born and Patella caerulea L.--selected as possible cosmopolitan biomonitors of trace metals in the Mediterranean area. The organisms were collected at five coastal sites in Favignana Island (Sicily, Italy), an area virtually uninfluenced by anthropogenic activities. In order to gain a more complete picture of both the environmental conditions of the experimental area and the bioaccumulation patterns of the selected organisms, soluble and total metal concentrations were determined in coastal water samples collected at the same stations. The picture of bioavailable metal loads in the different sites of the selected area provided by the four species was rather univocal. An overall trend of increased metal concentrations at the station in which the local harbour is located was clear. On the other hand, the metal concentrations recorded at the 'clean' stations generally fall in the range of the lowest values available in the literature and may be considered as useful background levels to which to refer for intraspecific comparison within the Mediterranean area. Implications in biomonitoring of the observed accumulation patterns, especially in the different tissues of Posidonia oceanica, are discussed.

Animals↗
PubMed2000

Primary structures of two hemagglutinins from the marine red alga, Hypnea japonica.

As the first examples among marine algal hemagglutinins, the primary structures of two hemagglutinins, named hypnin A-1 and A-2, from the red alga Hypnea japonica, were determined by Edman degradation. Both hemagglutinins were single-chain polypeptides composed of 90 amino acid residues including four half-cystines, all of which were involved in two intrachain disulfide bonds, Cys(5)-Cys(62) and Cys(12)-Cys(89). Hypnin A-1 and A-2 had calculated molecular masses of 9146.7 and 9109.7 Da which coincided with determined values, 9148 and 9109 Da, by electrospray ionization-mass spectrometry, respectively. Both hemagglutinins only differed from each other at three positions; Pro(19), Arg(31) and Phe(52) of hypnin A-1 as compared with Leu(19), Ser(31), and Tyr(52) of hypnin A-2. Approximately 43% of total residual numbers consisted of three kinds of amino acids: serine, glycine and proline. The hemagglutination activities were lost by reduction and alkylation of the disulfide bonds. The nature of the small-sized polypeptides, including disulfide bonds, may contribute to the extreme thermostability of the hemagglutinins. Sequence having overall similarity to hypnin A-1 or A-2 was not detected in databases. Unexpectedly, however, hypnins contained a motif similar to the alignment of the C-terminal conserved amino acids within carbohydrate-recognition domains of C-type animal lectins. Furthermore, interestingly, the hemagglutination activities were inhibited by a protein, phospholipase A-2 besides some glycoproteins, suggesting that hypnins may possess both a protein-recognition site(s) and a carbohydrate-recognition site(s).

Amino Acid Sequence↗
PubMed1999

Characterization of exo-(1,4)-alpha glucan lyase from red alga Gracilaria chorda. Activation, inactivation and the kinetic properties of the enzyme.

Exo-(1,4)-alpha glucan lyase (GLase) was purified from a red alga Gracilaria chorda. The enzyme was activated 1.3-fold in the presence of Ca(2+) and Cl(-) ions. The ions also stabilized the enzyme increasing the temperature of its maximum activity from 45 degrees C to 50 degrees C. GLase was inactivated by chemical modification with carbodiimide and a carboxyl group of the enzyme was shown essential to the lyase activity. A tryptophanyl residue(s) was also shown to be important for the activity and was probably involved in substrate binding. K(m) values of the enzyme were 2.3 mM for maltose, 0.4 mM for maltotriose and 0.1 mM for maltooligosaccharides of degree of polymerization (dp) 4-7, and the k(0) values for the oligosaccharides were similar (42-53 s(-1)). The analysis of these kinetic parameters showed that the enzyme has four subsites to accommodate oligosaccharides. The subsite map of GLase was unique, since subsite 1 and subsite 2 have large positive and small negative affinities, respectively. The subsite map of this type has not been found in other enzymes with exo-action on alpha-1,4-glucan. The K(m) and k(0) values for the polysaccharides were lower (0.03 mM) and higher (60-100 s(-1)), respectively, suggesting the presence of another affinity site specific to the polysaccharides.

Ammonium Chloride↗