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At least 649 records · Page 36Linked to original sources
PubMed1997

Purification and identification of apophycocyanin alpha and beta subunits from soluble protein extracts of the red alga Cyanidium caldarium. Light exposure is not a prerequisite for biosynthesis of the protein moiety of this photosynthetic accessory pigment.

Much controversy exists as to the level at which light exerts control over the biosynthesis of the photosynthetic apparatus in higher plants and other organisms. The eukaryotic red alga Cyanidium caldarium, like higher plants, undergoes light induction of chlorophyll synthesis. In addition to chlorophyll a the alga also synthesises the linear tetrapyrrole phycocyanobilin, which is combined with alpha or beta apobiliproteins to form phycocyanin, the major light-harvesting pigment in this organism. We have previously shown that the tetrapyrrole precursor 5-aminolaevulinic acid (ALA) can substitute for light in inducing the biosynthesis of the phycocyanobilin moiety of this protein. We have also described the appearance of a protein of similar isoelectric point and molecular weight to phycocyanin in ALA-fed cells (Turner et al., 1992, Plant Physiol Biochem 30: 309-314). We now report on the protein's immunological and sequence identity with phycocyanin alpha and beta subunits, and provide further evidence that bilin-apoprotein ligation is light dependent.

Amino Acid Sequence↗
PubMed1980

The comparative aspects of cell wall chemistry in the green algae (Chlorophyta).

The origin of a cell wall was an event of fundamental importance in the evolution of plants. In the green algae, cell walls apparently had independent origins in at least three lines of evolution. In this paper, the components of the cell wall were determined and compared in four filamentous green algae representing the charophycean, chlorophycean and ulvacean evoluationary lines. The walls of all four have hydroxyproline-containing proteins which separate into five or six bands upon SDS gel electrophoresis. Variation does exist, with the charophyte possessing fast moving electrophoretic bands and high hydroxyproline content, the chlorophytes having intermediate movement of bands and lower hydroxyproline content, and the ulvaecean representative possessing slow moving bands and a very low, if not questionable, hydroxyproline and saccharide content. Qualitative and quantitative estimates of wall proteins and sugars have been determined and compared. A hypothetical scheme of cell wall evolution based on these data, those of previous analyses, and recent phylogenetic schemes is presented. Although sound conclusions cannot be made until more information is available, the scheme might help to emphasize the areas most in need of additional research.

Amino Acids↗
PubMed1991

Characterization of a plasma membrane H(+)-ATPase from the extremely acidophilic alga Dunaliella acidophila.

Dunaliella acidophila is an unicellular green alga which grows optimally at pH 0-1 while maintaining neutral internal pH. A plasma membrane preparation of this algae has been purified on sucrose density gradients. The preparation exhibits vanadate-sensitive ATPase activity of 2 mumol Pi/mg protein/min, an activity 15 to 30-fold higher than that in the related neutrophilic species D. salina. The following properties suggest that the ATPase is an electrogenic plasma membrane H+ pump. (i) ATP induces proton uptake and generates a positive-inside membrane potential as demonstrated with optical probes. (ii) ATP hydrolysis and proton uptake are inhibited by vanadate, diethylstilbestrol, dicyclohexylcarbodiimide and erythrosine but not by molybdate, azide or nitrate. (iii) ATP hydrolysis and proton uptake are stimulated by fussicoccin in a pH-dependent manner as found for plants plasma membrane H(+)-ATPase. Unusual properties of this enzyme are: (i) the Km for ATP is around 60 microM, considerably lower than in other plasma membrane H(+)-ATPases, and (ii) the ATPase activity and proton uptake are stimulated three to fourfold by K+ and to a smaller extent by other monovalent cations. These results suggest that D. acidophila possesses a vanadate-sensitive H(+)-ATPase with unusual features enabling it to maintain the large transmembrane pH gradient.

Cations↗
PubMed1975

Observations of mechanisms of attachment in the green alga Ulva mutabilis Føyn. An ultrastructural and light microscopical study of zygotes and rhizoids.

The development of the rhizoid cells of the green alga Ulva mutabilis was investigated at the ultrastructural level paying special attention to the mechanism of attachment of the plant. Cytochemical data concerning the initial settling of the early zygote are also given. On the basis of histochemical staining and enzyme treatment it is concluded that the adhesive material secreted by the rhizoid cells is chemically different from that secreted by the zygote during the initial settling of the alga.

Cell Division↗
PubMed1992

Absorption of color additives and settling volume in water of blue-green alga, ishikurage (Nostoc commune).

The properties of ishikurage (Nostoc commune) and other algae were compared. Ishikurage and suizenji nori (Aphanothece sacrum) absorbed much more amaranth than others. They have a high settling volume (SV) in water. The high SV of ishikurage is attributable to its neutral detergent fiber (NDF). The acid detergent fiber (ADF) from the alga had a high amaranth absorption. However the absorption by the ADF did not explain the absorption by ishikurage. The results suggest that ishikurage may have a nutritional significance as a source of dietary fiber.

Absorption↗
PubMed1975

Effect of pesticides on blue-green algae and nitrogen-fixation.

The effects of the pesticides, amitrol, a derivative of amitrol (viz. 3,5-diamino-1,2,4-triazole), diquat, paraquat, linuron, MCPA, malathion, and monuron, were studied on the nitrogen-fixing algae, Anabaena cylindrica, Aulosira sp., Calothrix elenkenii. Chlorogloeae frischii, Cylindrospermum muscicola, Nostoc sp. from Collema tenax, Nostoc muscorum Tolypothrix tenuis, and Westiellopsis sp. In general, two types of response were discernible; an initial period of depression succeeded by an increased activity and an initial period of depression followed by a distinct decrease on prolonged incubation. The results indicate that some pesticidal compounds can severely limit the nitrogen-fixing capacities of blue-green algae, thereby affecting the overall nitrogen economy of soils in general.

Culture Media↗
PubMed1977

The effect of 2,4-dichlorophenoxyacetic acid on growth and nitrogen-fixation of blue-green alga Anabaenopsis raciborskii.

Sodium salt of 2,4-dichlorophenoxyacetic acid (80% active ingredient), commonly applied for the control of aquatic weeds, was used to observe its effect on the growth and nitrogen fixation of a heterocystous bloom forming blue-green alga Anabaenopsis raciborskii. A concentration of 10 microgram per ml of 2,4-D showed stimulation of growth and nitrogen fixation and these were almost unaffected in presence of its 100 microgram per ml in the medium. The alga could tolerate up to 800 microgram per ml in liquid culture media with and without nitrate nitrogen and up to 90 microgram per ml on to agar plates. Nitrogen fixation was inhibited in presence of its higher concentrations.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1991

An aldehyde-containing galactolipid from the red alga Gracilariopsis lemaneiformis.

An unprecedented aldehyde-containing digalactosyldiacylglycerol (DGDAG) has been isolated from the red alga Gracilariopsis lemaneiformis and structurally defined. Its structure was determined as 1-O-[5-hydroxy-12-oxo-dodeca-6(E),8(E),10(E)-trienoyl]-2-O-p almitoyl-3-O- [-beta-D-galactopyranosyl-6,1-alpha-D-galactopyranosyl]-glycerol by nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry and degradation to simple fragments. The identification of this aldehyde-containing DGDAG from G. lemaneiformis, in addition to our previous findings of unusual galactolipids, further indicates that this alga has unique lipoxygenase capacities.

Aldehydes↗
PubMed1993

Divinyl ethers and hydroxy fatty acids from three species of Laminaria (brown algae).

Three species of brown algae, Laminaria sinclairii, L. saccharina and L. setchellii, have been investigated for the presence of oxylipins. From one, L. sinclairii, three new divinyl ether fatty acids have been characterized as methyl ester derivatives (methyl 12-[1'(Z),3'(Z)-hexadienyloxy]-6(Z), 9(Z),11(E)-dodecatrienoate, methyl 12-[1'(Z),3'(Z)-hexadienyloxy]-9(Z), 11(E)-dodecadienoate, and methyl 14-[1'(Z),3'(Z)-hexadienyloxy]- 5(Z),8(Z),11(Z),13(E)-tetradecatetraenoate) by a variety of spectroscopic methods. In addition, one new [13(S)-hydroxy-6(Z),9(Z),11(E),15(Z)-octadecatetraenoic acid] and four known monohydroxy polyunsaturated fatty acids have been isolated from all three species as their methyl ester derivatives. The occurrence of these compounds in brown algae strongly suggests that these organisms possess an active lipoxygenase(s) with omega 6 specificity.

Fatty Acids↗
PubMed2002

Toxicological response of the green alga Scenedesmus bijuga to mercury and lead.

Effect of mercury or lead on the growth, bioaccumulation and some enzyme activities of one of the most common algae in River Nile, Scenedesmus bijuga, was determined. The cell count and chlorophyll a content decreased with an increase in mercury or lead concentrations in a culture medium, particularly at higher doses. Higher mercury and lead uptake was observed with increasing concentration of the elements. The alga accumulated appreciably more mercury than lead. At higher doses, the two elements strongly suppressed some enzyme activities of primary S. bijuga metabolism.

Acid Phosphatase↗
PubMed1982

Hydrocarbons in green and blue-green algae.

Liquid column chromatography and thin-layer chromatography were used to determine the total content of hydrocarbons and gas chromatography was used to evaluate composition of hydrocarbons in green algae (Chlorella kessleri, C. vulgaris, Chlorella sp., Scenedesmus acutus, S. acuminatus, S. obliquus) and the blue-green alga (Spirulina platensis) cultivated under autotrophic or heterotrophic conditions. In C. kessleri cultivated under heterotrophic conditions the content of hydrocarbons was found to be about 10(-2)% (per dry mass), whereas under autotrophic conditions it was about 10(-3)% (per dry mass). The highest content of hydrocarbons was detected in species of the genus Scenedesmus cultivated autotrophically (10(-1)%). Heptadecane and hexacosane were found as major alkanes, 1-heptadecene was detected among alkenes.

Alkanes↗
PubMed2003

Viability of dried vegetative cells or filaments, survivability and/or reproduction under water and light stress, and following heat and UV exposure in some blue-green and green algae.

Vegetative cells in dried, mucilagenous mass of Gloeocapsa aeruginosa and Aphanothece nidulans, reticulum of Hydrodictyon reticulatum, mucilagenous mass of Chroococcus minor, and filaments of Oedogonium sp. and Scytonema hofmanni died within 1/2, 1/2, 1/2, 1, 3 and 6 h, respectively, while dried vegetative filaments of Phormidium foveolarum retained under similar storage conditions viability for 4 d. P. foveolarum tolerated 1 mol/L NaCl. The resistance to desiccation in P. foveolarum exhibited similar dependence as that to heat or UV light. The water stress imposed on growing algae either on high-agar solid media or in NaCl-containing liquid media reduced at various levels or altogether inhibited the survival of vegetative parts in all, the cell division in C. minor, G. aeruginosa and A. nidulans, formation of heterocyst and false branch in S. hofmanni, oogonium in Oedogonium sp., and daughter net in H. reticulatum. Heat or UV shock of any level also produced similar effects as that by water stress. P. foveolarum tolerated low light level of 10 and 2 mumol m-2 s-1 and no light longer than the rest of other algae studied. Tolerance of microalgal forms to water, heat or UV stress depends primarily upon cell-wall characteristics or cell-sap osmotic properties rather than their habitats, morphology and prokaryotic or eukaryotic nature.

Chlorophyta↗
PubMed2003

Nitric oxide alleviates oxidative damage in the green alga Chlorella pyrenoidosa caused by UV-B radiation.

The effect of ultraviolet-B radiation (UV-B; 280-320 nm) on induction of nitric oxide was estimated in the suspensions of green alga Chlorella pyrenoidosa with or without the NO scavenger N-acetyl-L-cysteine, and reductants such as 1,4-dithiothreitol, glutathione (reduced form), and ascorbic acid. Exogenously added sodium nitroprusside (NO donor), glutathione, 1,4-dithiothreitol, and ascorbic acid were able to prevent chlorophyll loss mediated by UV-B. Addition of NO to algal suspensions irradiated by UV-B increased the activity of catalase and superoxide dismutase but lowered the activity of phenylalanine ammonia-lyase. UV-B thus appears to be a strong inducer of NO production, exogenously added NO and reductants protecting the green alga against UV-B-induced oxidative damage.

Acetylcysteine↗
PubMed2004

Tyrosinase inhibitors isolated from the edible brown alga Ecklonia stolonifera.

Extracts from seventeen seaweeds were determined for tyrosinase inhibitory activity using mushroom tyrosinase with L-tyrosine as a substrate. Only one of them, Ecklonia stolonifera OKAMURA (Laminariaceae) belonging to brown algae, showed high tyrosinase inhibitory activity. Bioassay-guided fractionation of the active ethyl acetate (EtOAc) soluble fraction from the methanolic extract of E. stolonifera, led us to the isolation of phloroglucinol derivatives [phloroglucinol (1), eckstolonol (2), eckol (3), phlorofucofuroeckol A (4), and dieckol (5)]. Compounds 1 approximately 5 were found to inhibit the oxidation of L-tyrosine catalyzed by mushroom tyrosinase with IC50 values of 92.8, 126, 33.2, 177, and 2.16 microg/mL, respectively. It was compared with those of kojic acid and arbutin, well-known tyrosinase inhibitors, with IC50 values of 6.32 and 112 microg/ mL, respectively. The inhibitory kinetics analyzed from Lineweaver-Burk plots, showed compounds 1 and 2 to be competitive inhibitors with Ki of 2.3x10(-4) and 3.1x10(-4) M, and compounds 3 approximately 5 to be noncompetitive inhibitors with Ki of 1.9x10(-5), 1.4x10(-3) and 1.5x10(-5) M, respectively. This work showed that phloroglucinol derivatives, natural compounds found in brown algae, could be involved in the control of pigmentation in plants and other organisms through inhibition of tyrosinase activity using L-tyrosine as a substrate.

Enzyme Inhibitors↗
PubMed2005

Hepatoprotective constituents of the edible brown alga Ecklonia stolonifera on tacrine-induced cytotoxicity in Hep G2 cells.

In this study, ethanolic extracts from 18 seaweed variants were assessed for hepatoprotective activity against tacrine-induced cytotoxicity in Hep G2 cells. Only one of these, Ecklonia stolonifera Okamura (Laminariaceae), a member of the brown algae, exhibited promising hepatoprotective activity. Bioassay-guided fractionation of the active ethyl acetate (EtOAc) soluble fraction obtained from the ethanolic extract of E. stolonifera, resulted in the isolation of several phlorotannins [phloroglucinol (1), eckstolonol (2), eckol (3), phlorofucofuroeckol A (4), and dieckol (5)]. Compounds 2 and 4 were determined to protect Hep G2 cells against the cytotoxic effects of tacrine, with EC50 values of 62.0 and 79.2 microg/mL, respectively. Silybin, a well characterized hepatoprotective agent, was used as a positive control, and exhibited an EC50 value of 50.0 microg/mL. It has been suggested that the phlorotannins derived from marine brown algae might prove useful sources in the development of novel hepatoprotective agents.

Benzofurans↗
PubMed2004

Inhibitory phlorotannins from the edible brown alga Ecklonia stolonifera on total reactive oxygen species (ROS) generation.

Reactive oxygen species (ROS) play an important role in the pathogenesis of many human degenerative diseases such as cancer, aging, arteriosclerosis, and rheumatism. Much attention has been focused on the development of safe and effective antioxidants. To discover sources of antioxidative activity in marine algae, extracts from 17 kinds of seaweed were screened for their inhibitory effect on total ROS generation in kidney homogenate using 2',7'-dichlorofluorescein diacetate (DCFH-DA). ROS inhibition was seen in three species: Ulva pertusa, Symphyocladia latiuscula, and Ecklonia stolonifera. At a final concentration of 25 microg/mL, U. pertusa inhibited 85.65+/-20.28% of total ROS generation, S. latiscula caused 50.63+/-0.09% inhibitory, and the Ecklonia species was 44.30+/-7.33% inhibition. E. stolonifera Okamura (Laminariaceae), which belongs to the brown algae, has been further investigated because it is commonly used as a foodstuff in Korea. Five compounds, phloroglucinol (1), eckstolonol (2), eckol (3), phlorofucofuroeckol A (4), and dieckol (5), isolated from the ethyl acetate soluble fraction of the methanolic extract of E. stolonifera inhibited total ROS generation.

Animals↗
PubMed1997

Analysis of the cluster of ribosomal protein genes in the plastid genome of a unicellular red alga Cyanidioschyzon merolae: translocation of the str cluster as an early event in the rhodophyte-chromophyte lineage of plastid evolution.

The nucleotide sequence of a cluster of ribosomal protein genes in the plastid genome of a unicellular red alga, Cyanidioschyzon merolae, which has been supposed to be the most primitive alga, was determined. The phylogenetic tree inferred from the amino acid sequence of ribosomal proteins of two rhodophytes, a chromophyte, a glaucophyte, two chlorophytes (land plants), a cyanobacterium, and three eubacteria suggested a close relationship between the cyanobacterium Synechocystis PCC6803 and the plastids of various species in the kingdom Plantae, which is consistent with the hypothesis of the endosymbiotic origin of plastids. In this tree, the two species of rhodophytes were grouped with the chromophyte, and the glaucophyte was grouped with the chlorophytes. Analysis of the organization of the genes encoding the ribosomal proteins suggested that the translocation of the str cluster occurred early in the lineage of rhodophytes and chromophytes after these groups had been separated from chlorophytes and glaucophytes.

Cyanobacteria↗