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At least 1,279 records · Page 71Linked to original sources
PubMed2005

Points of commitment to reproductive events as a tool for analysis of the cell cycle in synchronous cultures of algae.

Methods for determining the points of commitment for cell division are described for species of green algae dividing by multiple fission, both forming coenobia (Scenedesmus quadricauda) and releasing single daughter cells (Chlamydomonas eugametos, Scenedesmus armatus). The timing of commitment points was followed in detail in synchronous cultures of S. quadricauda grown under various light intensities, illumination regimes, and temperatures. The pre-commitment periods were rate limiting, while the post-commitment periods remained more or less constant under various light intensity. Temperature, on the other hand, affected both periods in a similar manner and they were prolonged with decreasing temperature.

Animals↗
PubMed2004

Zoosporangia survival, dehiscence and zoospore formation, and motility in the green alga Rhizoclonium hieroglyphicum as affected by different factors.

Urea at 200 ppm (probably serving as a nitrogen source), liquid Bold's basal medium at pH 7.5, temperature of about 22 degrees C and light intensity of about 40 micromol m(-2) s(-1) for 16 h a day induced rapid and/or abundant zoospores formation and zoosporangia dehiscence and favored zoospore liberation, speed and motility time period in the green alga Rhizoclonium hieroglyphicum. However, factors such as water stress (2 and 4 % agarized media, liquid media with 0.2-0.4 mol/L NaCl, 5-60 min blot-dryness of filaments), pH extremes of liquid media (at < or =6.5 and > or =9.5), temperature shock in liquid media (5 and 35 degrees C for > or =5 min), UV exposure (0.96-3.84 kJ/m2), lack of all nutrients from liquid medium (double distilled water), darkness, and presence of "heavy" metals (1-25 ppm Cu, Fe, Zn, Hg, Ni, Co) or organic substances (200-600 ppm captan or DDT, 800 and 1000 ppm 2,4-D, 50 and 400 ppm indole-3-acetic acid (3-IAA), 1000 and 2000 ppm urea, 100 and 200 ppm thiourea) in liquid media decreased and/or delayed at various levels either zoosporangia survival, zoospore formation or zoosporangia dehiscence and/or the rate of zoospore liberation from zoosporangia, zoospore speed and time period of motility in the media or totally inhibited all these processes. 3-IAA at 50 and 400 ppm induced zoosporangial papilla to grow into a tube-like projection of about 30-120 microm in length. Zoosporangial dehiscence rather than zoospore formation or zoosporangia survival, and zoospore motility period rather than zoospore speed are probably more sensitive to various adverse environmental factors. The rate of zoospores liberation from zoosporangium (possibly related directly to some extent on the zoospore number inside) is probably independent of zoospore speed in the medium.

Chlorophyta↗
PubMed2005

Endosymbiotic alga from green hydra under the influence of cinoxacin.

Cinoxacin (Cxn) showed a strong effect on the endosymbiotic alga Chlorella; it was significantly damaged. Changes in algal color, position, structure and ultrastructure were found. In some algal cells ultrastructures were completely destroyed. The antichloroplastal and antimitochondrial effect was especially expressed. Damage to the thylakoid system of chloroplasts was more pronounced with increasing Cxn concentration. Some of the mitochondria were swollen and some of them were completely destroyed. From the evolutionary point of view, the correlation between antibacterial, and antichloroplastal and antimitochondrial effect of Cxn points to the evolutionary connection of chloroplasts and mitochondria with eubacteria.

Animals↗
PubMed2004

The effect of nalidixic acid on growth and reproductive events in nucleocytosolic and chloroplast compartments in the alga Scenedesmus quadricauda.

The courses of rRNA accumulation, DNA replication, and nuclear division were followed both in the chloroplast and the nucleocytosolic compartments during the cell cycle in synchronized populations of the chlorococcal alga Scenedesmus quadricauda. Control and nalidixic acid-treated cultures were compared. Nalidixic acid (150 mg/L) was added either at the beginning of the cell cycle or consecutively during the cell cycle to subcultures transferred into the dark. If the inhibitor was applied at the beginning of the cell cycle, chloroplast DNA did not replicate and nucleoids did not divide. Chloroplast division, however, was coordinated in a timely fashion with cytokinesis even under conditions of blocked chloroplast DNA replication. While the growth rate was slowed down, the courses of reproductive processes in the nucleocytosolic compartment were not affected and their timing and the number of rounds were coordinated with growth rate as in the control culture. The rate of cytosolic rRNA synthesis was lower but no apparent effect was seen on the amount of rRNA that accumulated during the cell cycle. In contrast, lower levels of chloroplast rRNA were found at the end of the cell cycle compared with the control culture. Experiments in which cells were transferred to the dark during the cell cycle showed that the inhibitor affected none of the reproductive events in the nucleocytosolic compartment. In the chloroplast compartment, DNA replication was inhibited in inhibitor-treated cultures, but was unaffected in controls. The chloroplast nucleoids themselves divided even in the presence of the inhibitor, reducing their DNA content to a level which corresponded to that in freshly formed control daughter cells.

Chloroplasts↗
PubMed2003

Anti-oxidant activities of fucosterol from the marine algae Pelvetia siliquosa.

The anti-oxidant activities of fucosterol isolated from the marine algae Pelvetia siliquosa were investigated. Fucosterol exhibited a significant decrease in serum transaminase activities elevated by hepatic damage induced by CCl4-intoxication in rats. Fucosterol inhibited the sGOT and sGPT activities by 25.57 and 63.16%, respectively. Fucosterol showed the increase in the anti-oxidant enzymes such as hepatic cytosolic superoxide dismutase (SOD), catalase and glutathione peroxidase (GSH-px) activities by 33.89, 21.56 and 39.24%, respectively, in CCl4-intoxicated rats. These results suggest that fucosterol possess not only the anti-oxidant, but also the hepatoprotective activities in rats.

Administration, Oral↗
PubMed2003

Antioxidative properties of brown algae polyphenolics and their perspectives as chemopreventive agents against vascular risk factors.

Several polyphenolic compounds and complex mixtures were isolated from brown algae species. The 1,1-diphenyl-2-picryhydarzyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) of these compounds were evaluated to determine their physiological usefulness as antioxidants for vascular protection. The antioxidative protection of low-density lipoprotein (LDL) was also evaluated and compared with that of catechin, because the generation of oxidized LDL is one of the most active and specific risk factors contributing to atherogenesis. Oral administration to rats of a commercially available sample (VNP) containing 30% of these polyphenolic compounds and 70% dietary fiber revealed that the serum reducing capacity measured in terms of FRAP value was significantly elevated 30 min after the treatment, but declined rather quickly thereafter, indicating the good oral absorption of the compounds and their fast binding to the lumenal surface of the blood vessels. An eight-week, human, clinical trial (n=31) of VNP showed significant improvement in erectile function measured by IIEF (international index of erectile function) score. These results collectively demonstrated the usefulness of these polyphenolic compounds as fundamental chemopreventive agents against vascular risk factors originating from oxidative stress.

Animals↗
PubMed2003

Cholinesterase inhibitory activity of two farnesylacetone derivatives from the brown alga Sargassum sagamianum.

Two known farnesylacetone derivatives (1 and 2) were isolated from the Korean brown alga Sargassum sagamianum off Jeju Island, Korea. Compounds 1 and 2 were identified as (5E,10Z)-6,10,14-trimethylpentadeca-5,10-dien-2,12-dione and (5E,9E,13E)-6,10,4-trimethyl-pentadeca-5,9,13-trien-2,12-dione, respectively, by comparison with the literature data. Compounds 1 and 2 showed moderate acetylcholinesterase and butyrylcholinesterase inhibitory activities with IC50 values of 65.0 approximately 48.0 and 34.0 approximately 23.0 microM, respectively.

Butyrylcholinesterase↗
PubMed2000

The amino acid sequence of the agglutinin isolated from the red marine alga Bryothamnion triquetrum defines a novel lectin structure.

The primary structure of a lectin isolated from the red alga Bryothamnion triquetrum was established by combination of Edman degradation of sets of overlapping peptides and mass spectrometry. It contains 91 amino acids and two disulphide bonds. The primary structure of the B. triquetrum lectin does not show amino acid sequence similarity with known plant and animal lectin structures. Hence, this protein may be the paradigm of a novel lectin family.

Algal Proteins↗
PubMed1997

The reverse-transcriptase-like proteins encoded by group II introns in the mitochondrial genome of the brown alga Pylaiella littoralis belong to two different lineages which apparently coevolved with the group II ribosyme lineages.

The mitochondrial genome of the brown alga Pylaiella littoralis contains two different types of group II introns. They each encode complete complex proteins, i.e., with a reverse transcriptase domain, a maturase or X domain, and an endonuclease or H-N-H/zinc finger domain. To our knowledge, this is the first example of the presence in the same genome of introns belonging to subgroups IIA and IIB which both contain multidomained RT-like proteins. We describe the group IIA introns that interrupt the cox1 gene. The RT-like proteins contained in these introns were compared to those of the LSU rDNA group IIB introns. The phylogenetic relationships of these intron ORFs were investigated and the possible evolution of group II introns is discussed.

Amino Acid Sequence↗
PubMed1999

Utilization of xylose for growth by the eukaryotic alga, Chlorella.

A green alga, Chlorella, was found to be capable of utilizing xylose or other pentose sugars (xylitol, arabinose) for enhanced growth rates when grown in the light, but not when grown heterotrophically in the dark. With selection for growth in xylose-containing medium, it was possible to improve dramatically the ability of selected Chlorella strains to grow on xylose mixotrophically. Growth on arabinose or xylitol was not changed in the xylose-selected strains.

Arabinose↗
PubMed1998

Antioxidant and anti-inflammatory properties of C-phycocyanin from blue-green algae.

OBJECTIVE: Phycocyanin is a pigment found in blue-green algae which contains open chain tetrapyrroles with possible scavenging properties. We have studied its antioxidant properties. MATERIALS AND METHODS: Phycocyanin was evaluated as a putative antioxidant in vitro by using: a) luminol-enhanced chemiluminescence (LCL) generated by three different radical species (O2-, OH., RO.) and by zymosan activated human polymorphonuclear leukocytes (PMNLs), b) deoxyribose assay and c) inhibition of liver microsomal lipid peroxidation induced by Fe+2-ascorbic acid. The antioxidant activity was also assayed in vivo in glucose oxidase (GO)-induced inflammation in mouse paw. RESULTS: The results indicated that phycocyanin is able to scavenge OH. (IC50 = 0.91 mg/mL) and RO. (IC50 = 76 microg/mL) radicals, with activity equivalent to 0.125 mg/mL of dimethyl sulphoxide (DMSO) and 0.038 microg/mL of trolox, specific scavengers of those radicals respectively. In the deoxyribose assay the second-order rate constant was 3.56 x 10(11) M(-1) S(-1), similar to that obtained for some non-steroidal anti-inflammatory drugs. Phycocyanin also inhibits liver microsomal lipid peroxidation (IC50 = 12 mg/mL), the CL response of PMNLs (p < 0.05) as well as the edema index in GO-induced inflammation in mouse paw (p < 0.05). CONCLUSIONS: To our knowledge this is the first report of the antioxidant and anti-inflammatory properties of c-phycocyanin.

Animals↗
PubMed1999

Chlorophyll breakdown in higher plants and algae.

Leaf senescence is accompanied by the metabolism of chlorophyll (Chl) to nonfluorescent catabolites (NCCs). The pathway of Chl degradation comprises several reactions and includes the occurrence of intermediary catabolites. After removal of phytol and the central Mg atom from Chl by chlorophyllase and Mg dechelatase, respectively, the porphyrin macrocycle of pheophorbide (Pheide) a is cleaved. This two-step reaction is catalyzed by Pheide a oxygenase and RCC reductase and yields a primary fluorescent catabolite (pFCC). After hydroxylation and additional species-specific modifications, FCCs are tautomerized nonenzymically to NCCs inside the vacuole. Different subcellular compartments participate in Chl catabolism and, thus, transport processes across membranes are required. This review focuses on the catabolites and the individual reactions of Chl breakdown in higher plants. In addition, the pathway is compared to Chl conversion to red catabolites in an alga, Chlorella protothecoides. Finally, the significance and regulation of Chl degradation are discussed.

Chlorella↗
PubMed2001

Innate immune reactions stimulated by a lipopolysaccharide-like component of the alga Prototheca (strain 289).

We report on the influence of an LPS-like molecule (aLPS) from the pathogenic alga, Prototheca (strain 289) on insect and murine innate immune reactions. Insect innate reactions to infection include nodule formation, a process of entrapping bacterial cells in aggregates of hemocytes. We recorded eicosanoid-dependent, dose-related nodulation reactions to aLPS in hornworms (Manduca sexta). The insect reaction was attenuated by pre-incubating the aLPS with polymyxin-B. Conversely, the murine macrophages reacted to challenge with Escherichia coli LPS by secreting cytokines, but did not react to aLPS. We infer that, while highly conserved with respect to intracellular mechanisms of interaction, insect and mammalian immune surveillance systems differ in recognition of LPS molecular types.

Animals↗
PubMed1997

Biotransformation of 1-naphthalenesulfonic acid by the green alga Scenedesmus obliquus.

Under sulfate limitation, axenic batch cultures of the green alga Scenedesmus obliquus metabolized 1-naphthalenesulfonic acid and partially used the sulfonate as a source of sulfur. The main metabolite, 1-hydroxy-2-naphthalenesulfonic acid, which was not metabolized further in the algal culture, was formed by hydroxylation of the substrate in position 1 and by migration of the sulfonic acid group to position 2 of the naphthalene ring (NIH shift). A smaller amount of 1-naphthalenesulfonic acid was desulfonated. The resulting 1-naphthol was mostly transformed into 1-naphthyl beta-d-glucopyranoside.

Biotransformation↗
PubMed2001

Multidimensional liquid chromatography with parallel ICP MS and electrospray MS/MS detection as a tool for the characterization of arsenic species in algae.

An analytical strategy was developed for the characterization of arsenic species in a Laminaria algae. The approach was based on multidimensional liquid chromatography (LC) including sample extract cleanup by size-exclusion LC, separation of arsenic species by anion-exchange LC, verification of the chromatographic purity of arsenic-containing fractions, and their further purification, if necessary, by reversed-phase (RP) HPLC. The complementarity of ICP MS, used as the chromatographic detector, and ES MS/MS, employed for the identification of the peaks observed, was demonstrated. The species found were: arsenosugar A 11.7+/-0.5 microg g(-1), AsV 10.9+/-2.1 microg g(-1), arsenosugar B 2.22+/-0.07 microg g(-1), arsenosugar D 1.5+/-1.2 microg g(-1), a newly detected arsenosugar 1.13+/-0.07 microg g(-1), arsenosugar C 0.61+/-0.04 microg g(-1), DMA 0.42+/-0.02 microg g(-1) and these accounted for >99% of the arsenic present. The identities of all the species, except the newly detected compound, were doubly checked by matching the retention times of chromatographically pure (after the 3rd LC dimension) species with standards and by ES MS/MS.

Animals↗
PubMed2000

Comparison of open microwave digestion and digestion by conventional heating for the determination of Cd, Cr, Cu and Pb in algae using transverse heated electrothermal atomic absorption spectrometry.

A comparison between open microwave digestion and digestion by conventional heating was carried out for the determination of Cd, Cr, Cu, and Pb in two algae matrices using transverse heated electrothermal atomic absorption spectrometry (ETAAS). A SRM GBW 08504 cabbage was also analysed. These matrices were digested with HNO3, using a quartz vessel for microwave digestion and PFA vessel for digestion by conventional heating. Cd, Cu and Cr were determined without any modifier, while magnesium nitrate and ammonium phosphate mixed modifier was used for Pb. Results obtained by both the procedures were in good agreement with each other at 95% confidence level, and for SRM GBW 08504 cabbage the values agree well with the certified values. The limits of detection obtained were 0.0004, 0.060, 0.065 and 0.054 mg/kg for Cd, Cr, Cu, and Pb, respectively, using the microwave digestion process. The RSD for Cd was 10-15% and for the other elements 5-10%.

Bryopsida↗
PubMed2000

Determination of 'arsenosugars' in algae with anion-exchange chromatography and an inductively coupled plasma mass spectrometer as element-specific detector.

The retention behavior of four naturally occurring dimethylarsinoylribosides with -CH2-CHOH-CH2X (X = OH, HO3POCH2CHOHCH2OH, SO3H, OSO3H) as aglycones, of arsenous acid, arsenic acid, methylarsonic acid, and dimethylarsinic acid was investigated on a Hamilton PRP-X100 anion-exchange column with aqueous solutions of ammonium dihydrogen phosphate (20 mmol/L) in the pH range of 3.8-9.0 as mobile phase. A HP 4500 inductively coupled plasma mass spectrometer (ICP-MS) served as arsenic-specific detector. The influence of pH, temperature, and the concentration of methanol in the mobile phase on the retention times of these arsenic compounds was explored. An aqueous 20 mM ammonium dihydrogen phosphate solution at pH 5.6 at a column temperature of 40 degrees C was considered optimal as it allowed the separation of seven of the arsenic compounds within 16 min. Only arsenous acid and the ribose with the glycerol aglycone have overlapping signals with both migrating almost with the solvent front. At a concentration of 0.50 ng As mL(-1) the relative standard deviations (n = 3) of the signal areas of the eight arsenic compounds was in the range from 3.5 to 8.1%. The linear calibration curves (peak areas) from 0.5 to 10 ng/mL had correlation coefficients > 0.997. Extracts obtained from the brown algae Fucus spiralis and Halidrys siliquosa were chromatographed under the optimized conditions. Both species contained the sulfate riboside as the major arsenic compound (approximately 55% of total extractable arsenic) together with the sulfonate- and phosphate riboside. Arsenic acid was a significant constituent of Halidrys siliquosa (approximately 6.5%), but was not detected in Fucus spiralis.

Arsenicals↗
PubMed2001

Bioconcentration of linear alkylbenzene sulfonates and their degradation intermediates in marine algae.

Sorption experiments using different homologues of linear alkylbenzene sulfonate (LAS) and sulfophenylcarboxylic acid (SPC) on several marine microalgae have been carried out. The steady state seems to be reached in the first 4 hours. Longer exposure times lead to biodegradation of the compound and, therefore, to an overestimation of the bioconcentration factor. Sorption coefficients are higher for Nannochloropsis gaditana, for example, 1,293 Lkg(-1) for C11-LAS and 525 Lkg(-1) for C11-SPC versus 727 Lkg(-1) for C11-LAS and 28 Lkg(-1) for C11-SPC for Dunaliella salina. For both algae an increase in the sorption coefficient is observed when the polarity of the compound decreases (C5-SPC<C11-SPC<C11-LAS approximately/= C12-LAS). The sorption of C11-LAS on D. salina is fitted to a linear Freundlich isotherm (K=176+/-0.02, n=0.964+/-0.02).

Alkanesulfonic Acids↗