Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “algae”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88Linked to original sources
PubMed1996

Isolation of a non-steroidal contragestative agent from Sri Lankan marine red alga, Gelidiella acerosa.

This study reports the isolation of a non-steroidal contragestative agent from the Sri Lankan marine red alga, Gelidiella acerosa. One-hundred grams of MeOH-CH2Cl2 (1:1) crude extract of G. acerosa was initially partitioned into hexane, CH2Cl2 and EtOAc, respectively, using the modified Kupchan scheme. At each separation step, all the resulting fractions were tested for contragestative effects in pregnant rats. The fertility was assessed in terms of the number of viable implants following oral administration of fractions (co-precipitated with polyvinylpyrrolidone), on day 1 through day 7 of pregnancy. The hexane fraction with highest activity was subjected to gel filtration through Sephadex LH-20, vacuum liquid chromatography over TLC-grade silica, two open-column chromatography runs over silica gel (60-120 mesh), and HPLC to isolate the active component. Nuclear magnetic resonance and infrared spectroscopic analysis revealed that the contragestative agent of G. acerosa is a sphingosine derivative.

Animals↗
PubMed1998

Vasoconstriction induced by zooxanthellatoxin-B, a polyoxygenated long-chain product from a marine alga.

We found that zooxanthellatoxin-B from a symbiotic marine alga, Symbiodinium sp., caused a concentration-dependent contraction of the rabbit isolated aorta at concentrations of 10(-7)-10(-5) M. Verapamil (10(-6) M) and mefenamic acid (10(-5) M) significantly attenuated the contractile response to zooxanthellatoxin-B at lower concentrations (10(-7)-10(-6) M) but not at higher concentrations (3 X 10(-6)-10(-5) M). The response to zooxanthellatoxin-B was partly inhibited by phentolamine (10(-6) M), whereas it was potentiated by ouabain (10(-5) M). Tetrodotoxin (10(-6) M), methysergide (10(-6) M), chlorpheniramine (10(-6) M) or indomethacin (3 X 10(-6) M), however, did not affect it. The zooxanthellatoxin-B-induced contraction was abolished by incubation in Ca2+-free solution. The contractile response increased in a concentration-dependent fashion with Ca2+ (0.03 and 10 mM) or Sr2 + (0.10 and 10 mM). After treatment with verapamil (10(-6) or 5 X 10(-6) M), the concentration-contractile response curves for Ca2+ and Sr2+ in the presence of zooxanthellatoxin-B were shifted to the right in parallel. MgCl2 (10 mM) shifted the concentration-response curve for Ca2+ more markedly than did verapamil. Zooxanthellatoxin-B increased tissue Na+ and reduced tissue K+ contents in the aorta, suggesting that zooxanthellatoxin-B increases Na+ and K+ permeability across the plasma membrane. These results suggest that the zooxanthellatoxin-B-induced contraction of the aorta is caused mainly by a direct action on smooth muscle, i.e., an increase in Ca2+ permeability that occurs at least partly through voltage-sensitive Ca2+ channels as well as through nonselective cation channels in the cell membrane of smooth muscle.

Animals↗
PubMed2000

Identification and characterization of a eukaryotically encoded rubredoxin in a cryptomonad alga.

We have identified an open reading frame with homology to prokaryotic rubredoxins (rds) on a nucleomorph chromosome of the cryptomonad alga Guillardia theta. cDNA analysis let us propose that the rd preprotein has an NH(2)-terminal extension that functions as a transit peptide for import into the plastid. Compared to rds found in non-photosynthetic prokaryotes or found in bacteria that exhibit an anoxigenic photosynthesis apparatus, nucleomorph rd has a COOH-terminal extension, which shows high homology exclusively to the COOH-termini of cyanobacterial rds as well as to a hypothetical rd in the Arabidopsis genome. This extension can be divided into a putative membrane anchor and a stretch of about 20 amino acids with unknown function linking the common rd fold to this anchor. Overexpression of nucleomorph rd in Escherichia coli using a T7 RNA polymerase/promotor system resulted in a mixture of iron-containing holorubredoxin and zinc-substituted protein. Preliminary spectroscopic studies of the iron form of nucleomorph rd suggest the existence of a native rd-type iron site. One-dimensional nuclear magnetic resonance spectroscopy of recombinant Zn-rd suggests the presence of a stable tertiary fold similar to that of other rd structures determined previously.

Amino Acid Sequence↗
PubMed1997

Repetitive Ca2+ spikes in a unicellular green alga.

Cytosolic Ca2+ activity ([Ca2+]cy) and membrane potential were measured simultaneously in the unicellular green alga Eremosphaera viridis. Steady state [Ca2+]cy was about 160 nM. A 'light-off' stimulus induced a transient elevation of [Ca2+]cy ([Ca2+]cy spike) in parallel with a transient hyperpolarization of the plasma membrane. Caffeine and Sr2+, known to release Ca2+ from intracellular stores in animal cells, induced repetitive [Ca2+]cy spikes in Eremosphaera which were always accompanied by parallel repetitive transient hyperpolarizations. These transient hyperpolarizations could be used as an indicator for [Ca2+]cy spikes. Repetitive [Ca2+]cy spikes in Eremosphaera were similar to repetitive [Ca2+]cy spikes in excitable animal cells. The mechanisms underlying these [Ca2+]cy oscillations seem to be comparable in animal and plant cells.

Caffeine↗
PubMed1998

Na+-ATPase from the plasma membrane of the marine alga Tetraselmis (Platymonas) viridis forms a phosphorylated intermediate.

Plasma membranes isolated from the marine unicellular alga Tetraselmis (Platymonas) viridis were phosphorylated by [gamma-32P]ATP, and membrane proteins were then analyzed by PAGE in SDS, under acidic conditions. Three radioactive components with apparent molecular masses of 100 kDa, 76 kDa, and 26 kDa were detected. The phosphorylation of one of them, the 100 kDa polypeptide, was specifically stimulated by Na+. Vanadate almost completely inhibited the Na+-mediated phosphorylation of the peptide. The phosphate bound to this peptide underwent rapid turnover and was discharged by hydroxylamine. The 100 kDa phosphopeptide was sensitive to ADP. The conclusion is drawn that the 100 kDa phosphopeptide is a phosphorylated intermediate of the Na+-transporting ATPase in the T. viridis plasma membrane.

Adenosine Diphosphate↗
PubMed1999

Purification and characterization of hydrogenase from the marine green alga, Chlorococcum littorale.

Hydrogenase from the marine green alga, Chlorococcum littorale, was purified 1485-fold, resulting in a specific activity for hydrogen evolution of 75.7 micromol/min/mg of protein at 25 degrees C, using reduced methyl viologen as an electron donor. The K(m) value for methyl viologen was 0.5 mM. The purity of the enzyme was judged by native PAGE. The molecular weight was estimated to be 55 kDa by SDS-PAGE, and 57 kDa by gel filtration. The optimum temperature and pH value for hydrogen evolution were 50 degrees C and 7.5, respectively. The partially purified hydrogenase catalyzed hydrogen evolution from ferredoxin that had been isolated from the same cells, but not from NADH or NADPH. The K(m) value for ferredoxin was 0.68 microM. The enzyme was extremely oxygen sensitive, losing over 95% of its activity upon exposure to air within minutes, even at 4 degrees C. Two peptide fragments were obtained from the hydrogenase protein digested enzymatically, and their amino acid sequences were determined. No significant homology was found to any other known sequences of hydrogenases.

Amino Acid Sequence↗
PubMed1999

Redox control of hydrogenase activity in the green alga Scenedesmus obliquus by thioredoxin and other thiols.

The activity of the NiFe-hydrogenase from the green alga Scenedesmus obliquus is inhibited by both algal thioredoxins f and I+II, and by Escherichia coli thioredoxin. The strongest inhibition was observed with homologous chloroplastic thioredoxin f (I50 = 21 nM) and E. coli thioredoxin (I50 = 83 nM). For the homologous cytoplasmic thioredoxins I+II an I50 of 667 nM was determined. Glutathione shows a similar but much less pronounced inhibitory effect whereas dithiothreitol had no effect. In addition to glucose-6-phosphate dehydrogenase, NiFe-hydrogenase is only the second enzyme known to be inhibited by reduced thioredoxin.

Chlorophyta↗
PubMed1989

Application of an asymmetrical flow field-flow fractionation channel to the separation and characterization of proteins, plasmids, plasmid fragments, polysaccharides and unicellular algae.

The asymmetrical flow field-flow fractionation channel has been improved by introduction of a different sample loading method, downstream central injection, which reduces sample relaxation and focusing time considerably and allows the concentrations of material in the channel, thereby enabling the loading of very large sample volumes. The performance of the channel was demonstrated by the separation of a protein from its dimer, retention of nucleic acids, i.e., plasmids and enzymatically cleaved plasmids, hyaluronate and unicellular algae.

Chemical Fractionation↗
PubMed2001

Supercritical fluid extraction for liquid chromatographic determination of carotenoids in Spirulina Pacifica algae: a chemometric approach.

An experimental design procedure was used to investigate the effects of some operating parameters on the supercritical fluid extraction of carotenoids beta-carotene, beta-cryptoxanthin and zeaxanthin from Spirulina Pacifica algae, a carotenoid-rich dietary product. Variables tested were temperature and pressure of the supercritical fluid, dynamic extraction time and percentage of ethanol added as the modifier. Each variable was tested at three levels; 31 experiments were performed in random order. Analyses of the extracts were performed by high-performance liquid chromatography with UV-Vis photodiode array detection. Analytical responses (chromatographic peak areas) were processed by using a stepwise multiple regression analysis, in order to find polynomial functions describing the relationships between variables and responses. For all the analytes the experimental conditions providing the highest extraction yield inside the experimental domain considered were found. Supercritical fluid extraction results obtained in these conditions were compared with those obtained by performing solvent extraction in order to evaluate the effectiveness of the supercritical fluid extraction procedure.

Carotenoids↗
PubMed1998

Identification of eicosanoids in the red algae, Gracilaria asiatica, using high-performance liquid chromatography and electrospray ionization mass spectrometry.

Identification of eicosanoids which are metabolites of arachidonic acid in red algae Gracilaria asiatica, one of the popular seaweeds in Japan, was carried out using high-performance liquid chromatography (HPLC) interfaced with electrospray ionization mass spectrometry. Prostaglandin (PG) E2, 15-keto-PGE2, and 8-hydroxyeicosatetraenoic acid (HETE) were detected as major eicosanoids and PGA2, leukotriene B4 as minor ones in G. asiatica. 8- and 12-HETE had the same retention time in HPLC analysis, but using this analytical method, we were able to identify them.

Chromatography, High Pressure Liquid↗
PubMed2000

Living in the intertidal zone - seasonal effects on heterosides and sun-screen compounds in the red alga Bangia atropurpurea (Bangiales).

The seasonal patterns of daylength and ultraviolet radiation (UVB and UVA) at Williamstown, Victoria, Australia were measured (October 1995-May 1996) and are considered in relation to levels of heterosides (soluble sugar compounds: D-isofloridoside, floridoside and L-isofloridoside) and sun-screen compounds (mycosporine-like amino acids: MAAs) in the intertidal red alga Bangia atropurpurea. UVB peaked in December-January at 2.2-2.4 W m(-2) and UVA also peaked at 70 W m(-2) in the same period. Total heteroside concentrations were highest (1230-1900 mmol kg(-1) dry weight) during November-December with floridoside and D-isofloridoside being 90% of the total. In late February through mid-April total heteroside contents were lower (315-905 mmol kg(-1) dry weight) with L-floridoside being as much as 34% of the total indicating a seasonal effect. Total MAAs varied from 3.4 to 7.1 mg g(-1) dry weight (mean 4.9 mg g(-1) dry weight) with both highest and lowest levels occurring in February. Porphyra-334 constituted 83 to 97% of this total with asterina-330, palythine and palythinol being 3-17%. Although maximum MAA concentrations did not show any significant parallel with the peak UV values, the quantitative data point to Bangia cells over the course of the seasons always loaded up with these photoprotective compounds.

Journal Article↗
PubMed1990

Structure of the [2Fe-2S] ferredoxin I from the blue-green alga Aphanothece sacrum at 2.2 A resolution.

Crystals of a [2Fe-2S] ferredoxin (Fd) I with a relative molecular mass of 10,480 were obtained from the blue-green alga Aphanothece sacrum. Each asymmetric unit of the crystal contains four molecules. An electron density map calculated by the single isomorphous replacement method with the anomalous dispersion at 2.5 A resolution was refined by averaging the four molecules in the asymmetric unit. Positional and isotropic thermal parameters for the non-hydrogen atoms of the four molecules and 158 water molecules were refined to an R-factor (R = sigma[Fo-Fc[/sigma Fo) of 0.23 by the restrained least-squares method. The estimated root-mean-square (r.m.s.) error for the atomic positions is 0.3 A. The r.m.s. deviations of equivalent C alpha atoms of the asymmetric-unit molecules superposed by the least-squares method average 0.35 A. The Fd molecule has a structure like the beta-barrel in the molecule of the [2Fe-2S] Fd from Spirulina platensis. A [2Fe-2S] cluster is bonded covalently to the protein molecule by four Fe-S, in which three of the Fe-S bonds are in a loop segment from position 38 to 47. The hydrophobic core inside the beta-barrel is formed by seven conservative residues: Val15, Val18, Ile24, Leu51, Ile74, Ala79 and Ile87. The molecular surface around Tyr23, Tyr80 and the active center may interact with ferredoxin-NADP+ reductase. One of the two iron atoms of the [2Fe-2S] cluster should be more easily reduced than the other because of differences in the hydrogen-bonding scheme and the hydrophobicity around the atoms.

Amino Acid Sequence↗
PubMed2002

Using genetic techniques to investigate the sources of the invasive alga Caulerpa taxifolia in three new locations in Australia.

The invasive green alga Caulerpa taxifolia has gained a high profile due to 'outbreaks' in the Mediterranean and California. During the year 2000 three new discrete locations colonised by abundant C. taxifolia were discovered in New South Wales (NSW), Australia. Sequencing of the internal transcribed spacer (ITS) region of the ribosomal DNA was used to explore the source(s) of these new records, which is an important prerequisite for subsequent environmental management responses. Our results indicate that the NSW C. taxifolia originated from several sources and, hence, through different invasion events. For two of the new records (Port Hacking, Careel Bay) it can be excluded that they are derived from the so-called "aquarium strain" of C. taxifolia, closely related to the invasive Mediterranean populations. Port Hacking is likely to have originated from tropical native populations. However, samples from Lake Conjola cannot be sufficiently distinguished with the applied technique from native C. taxifolia in Moreton Bay and the Mediterranean/"aquarium strain".

Base Sequence↗
PubMed1988

Algae as possible sources of antitumoural agents. Preliminary evaluation of the "in vitro" cytostatic activity of crude extracts.

Aqueous, ethanolic and chloroformic extracts of 13 algae from the Gulf of Trieste (North Adriatic Sea) were assayed in vitro against human tumour established cell line (KB). Some of them exhibit a noteworthy cytostatic activity, in particular Dictyopteris membranacea (Stackh.) Batt., which significantly inhibits the growth of the cell cultures in all the three different crude extracts, was quantitatively screened in different periods of the year for the presence of cytostatic compound(s).

Antineoplastic Agents↗
PubMed2000

Fatty acid amides from freshwater green alga Rhizoclonium hieroglyphicum.

Freshwater green algae Rhizoclonium hieroglyphicum growing in the Ural Mountains were examined for their fatty acid amides using capillary gas chromatography-mass spectrometry (GC-MS). Eight fatty acid amides were identified by GC-MS. (Z)-9-octadecenamide was found to be the major component (2.26%).

Amides↗
PubMed2001

(S)-12-hydroxygeranylgeraniol-derived diterpenes from the brown alga Bifurcaria bifurcata.

Four novel diterpenes were isolated from the brown alga Bifurcaria bifurcata collected off the Atlantic coast from Morocco, and their structures established by spectral and chemical methods. These compounds are acyclic diterpenes derived from (S)-12-hydroxygeranylgeraniol. One of them is its dehydration product at C-12, while the others are its oxidation derivatives: the methyl ester of the acid at C-1 and two stereoisomers (Z and E) of the aldehyde at C-1. These results are discussed from a chemotaxonomic point of view.

Diterpenes↗
PubMed2001

Sterol composition of Aureoumbra lagunensis, the Texas brown tide alga.

Aureoumbra lagunensis, the alga responsible for the "Texas brown tide", contains (E)-24-propylidenecholesterol (35.7% of total sterols) as its dominant sterol, in common with other members of the Pelagophyceae. Other major sterols are stigmasterol (22.2%), sitosterol (19.2%), cholesterol (14.1%), and (24R)-24-propylcholesterol (5.2%). Trace amounts of 24-methylenecholesterol, crinosterol, clerosterol, campesterol, dihydrobrassicasterol, and 24-isopropylcholesterol were also detected.

Chromatography, High Pressure Liquid↗
PubMed2002

C(15) Acetogenins from the red alga Laurencia obtusa.

Four C(15) acetogenins, 13-epilaurencienyne (3Z) (1), 13-epipinnatifidenyne (3E) (2), (3E, 6S(*), 7R(*), 9S(*), 10S(*), 12R(*))-9-chloro-13-bromo-6:12-epoxy-7, 10-diacetoxypentadec-3-en-1-yne (3), (3Z, 6S(*), 7R(*), 9S(*), 10S(*), 12R(*))-9-chloro-13-bromo-6:12-epoxy-7, 10-diacetoxypentadec-3-en-1-yne (4), along with the known 13-epilaurencienyne (3E) (5), have been isolated from the organic extract of the red alga Laurencia obtusa, collected in the Aegean Sea, Greece. The structures of the new natural products, as well as their relative stereochemistry, were established by means of spectral data analysis, including 2D NMR spectroscopic experiments. Some of the new metabolites exhibited significant insecticidal activity.

Animals↗