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PubMed1994

Purification and some properties of a trehalase from a green alga, Lobosphaera sp.

An unicellular green alga identified as Lobosphaera sp. by morphological observations was selected as a source of trehalase. The alga grew well heterotrophically and produced intracellular trehalase using Polypepton, yeast extract, and glycerol as nutrients. The enzyme was highly purified by ammonium sulfate fractionation, column chromatography on DEAE-Toyopearl, Sepharose CL-4B, and SP-Toyopearl. The molecular mass was estimated to be 400 kDa by gel filtration. SDS-PAGE indicated that the enzyme consisted of two subunits with a molecular mass range of 180-220 kDa and it contained carbohydrates. The enzyme was most active at pH 5.5 and at 65 degrees C and stable between pH 4-9 and below 65 degrees C. Fe3+ inactivated the enzyme. Sucrose was a competitive inhibitor with a Ki of 7.5 mM. The enzyme specifically hydrolyzed trehalase with a Km of 0.6 mM.

Carbohydrate Metabolism↗
PubMed2006

Cytoplasmic localization of the single glutamine synthetase in a unicellular red alga, Cyanidioschyzon merolae 10D.

Glutamine synthetase (GS) is a key enzyme for nitrogen assimilation. Although GS contains multiple molecular species found in plastid, mitochondria and cytoplasm in green plants and algae, genome analysis of a red alga, Cyanidioschyzon merolae, revealed a single nuclear gene for GS (CmGS). In this study, we experimentally determined the CmGS localization in the cytoplasmic compartment.

Cell Fractionation↗
PubMed2006

Characterization of a corrinoid compound in the edible (blue-green) alga, Suizenji-nori.

The edible blue-green alga (cyanobacterium), Suizenji-nori, contained 143.8+/-22.4 microg of vitamin B(12) per 100 g dry weight of the alga (mean+/-SE, n=4). A corrinoid compound was purified from the dried Suizenji-nori, and partially characterized. The silica gel 60 TLC and reversed-phase HPLC patterns of the purified corrinoid compound were not identical to those of true vitamin B(12), but to those of pseudovitamin B(12) which is inactive for humans.

Chromatography, High Pressure Liquid↗
PubMed1998

Inhibition of icosanoid production in MC/9 mouse mast cells by n-3 polyunsaturated fatty acids isolated from edible marine algae.

The effects of two polyunsaturated fatty acids, 18:4n-3 and 16:4n-3 purified from the marine algae, Undaria pinnatifida and Ulva pertusa, on icosanoid production in MC/9 mouse mast cells were assessed. Both fatty acids suppressed the production of leukotriene B4 (LTB4), leukotriene C4 (LTC4), and 5-hydroxyeicosatetraenoic acid (5-HETE). The order of the suppressive activity for the two marine algae-derived fatty acids and three other common polyunsaturated fatty acids was as follows; 22:6n-3 = 18:4n-3 = 18:3n-3 > 20:5n-3 = 16:4n-3 for LTB4; 22:6n-3 = 18:4n-3 = 18:3n-3 > 16:4n-3 > 20:5n-3 (no suppression) for LTC4; 22:6n-3 = 18:4n-3 > 18:3n-3 > 20:5n-3 = 16:4n-3 for 5-HETE.

Animals↗
PubMed2001

Isolation, growth, ultrastructure, and metal tolerance of the green alga, Chlamydomonas acidophila (Chlorophyta).

An acidophilic volvocine flagellate, Chlamydomonas acidophila (Volvocales) that was isolated from an acid lake, Katanuma, in Miyagi prefecture, Japan was studied for growth, ultrastructural characterization, and metal tolerance. Chlamydomonas acidophila is obligately photoautotrophic, and did not grow in the cultures containing acetate or citrate even in the light. The optimum pH for growth was 3.5-4.5. To characterize metal tolerance, the toxic effects of Cd, Co, Cu, and Zn on this alga were also studied. Effective metal concentrations, which limited the growth by 50%, EC50 were measured, after 72 h of static exposure. EC50s were 14.4 microM Cd2+, 81.3 microM Co2+, 141 microM Cu2+, and 1.16 mM Zn2+ for 72 h of exposure. Thus, this alga had stronger tolerance to these metals than other species in the genus Chlamydomonas.

Adaptation, Physiological↗
PubMed2002

Uptake and physiological function of vitamin B12 in a photosynthetic unicellular coccolithophorid alga, Pleurochrysis carterae.

The photosynthetic coccolithophoid alga, Pleurochrysis (Hymenomonas) carterae, could take up and accumulate exogenous vitamin B12, most of which was converted into the coenzyme forms of vitamin B12. Two vitamin B12-dependent enzyme activities (methylmalonyl-CoA mutase, 2.6+/-0.4 nmol/min/mg protein and methionine synthase, 85.1+/-38.9 pmol/min/mg protein) could be found in a cell homogenate of the vitamin B12-supplemented alga. Most of the methylmalonyl-CoA mutase activity and 19.2% of the vitamin B12 accumulated by the algal cells were recovered in the macromolecular fractions with Mr of 150 kDa, although the remaining vitamin B12 was found only in free vitamin B12 fractions.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMedDate not supplied

Public health benefits of using algae for simultaneous multiple metal extraction from waters.

Algae have been described as inexpensive organisms for the efficient extraction and recovery of heavy-metals from polluted waters. This method is most effective when the solution conditions are adjusted for the selective adsorption of individual metals. Experiments that are designed for extracting single metals, however, do not accurately assess either environmental or water systems. In this article, we distinguish between using algae to remove individual versus multiple metals. Simultaneous multiple metal extraction has a major disadvantage, however, because all the metals in a solution may not be removed with great efficiency. Single-metal extraction is more readily optimized for almost 100% recovery.

Animals↗
PubMedDate not supplied

[Activity of aminotransferases in the blue green alga Anacystis nidulans].

The blue-green alga Anacystis nidulans (strain L 1402-1) was grown at +37 degrees C in air (0.03 vol% CO2 and in air enriched with 3.0 vol% CO2. The effects of several inhibitors on the activity of aminotransferases, 14CO2 fixation and radioactive photosynthetic products of Anacystis were studied. No serine-pyruvate aminotransferase activity could be found in 10-2 M isonicotinyl hydrazide (INH); under the influence of this inhibitor aspartate and alanine aminotransferase were decreased about 49% respectively 17.6%. Serine-pyruvate and alanine aminotransferase activity decreased to more than 50% in 10-3 M glyoxalbisulfite. The obtained inhibitory effect of 10-4 M HPMS on serine-pyruvate aminotransferase (35%) was stronger than one the other aminotransferases. DCMU (5 x 10-6 M) inhibition on alanine aminotransferase activity was 83.7%. Under the influence of 10-3 M glyoxalbisulfite no 14C-labelled amino acids could be detected after 5 min photosynthesis; 14C-labelling of phosphoenolpyruvate, malate, phosphoglycolate and glycolic acid increased. Isonicotinyl hydrazide (10-2 M) caused in comparison to the control experiment a lower radioactivity in aspartate glutamate and phosphoenolpyruvate. The results are discussed with reference fo the operation of the glycolate pathway and a carboxylation reaction of phosphoenol-pyruvate in the blue-green alga Anacystis nidulans.

Alanine Transaminase↗
PubMed1979

Inhibition of photosynthetic electron transport in tobacco chloroplasts and thylakoids of the blue green alga Oscillatoria chalybea by an antiserum to synthetic zeaxanthin.

An antiserum to synthetic Zeaxanthin inhibits photosynthetic electron transport on the oxygen-evolving side of photosystem II in tobacco chloroplasts and thylakoids of the filamentous blue-green alga Oscillatoria chalybea. The inhibition site lies for both species between the site of electron donation of water or tetramethyl benzidine and that of diphenyl carbazide or manganese II ions. Typical photosystem I reactions are not impaired by the antiserum. The effect of the antiserum concerning the inhibition site is practically identical to that of the earlier described antiserum to violaxanthin. However, the degree of inhibition seems to be generally somewhat lower with the antiserum to Zeaxanthin, than with that to violaxanthin which hints at a lesser accessibility of zeaxanthin, in the tylakoid membrane in comparison to violaxanthin. In the course of these investigations new evidence was obtained that the oxygen-evolving side of the electron transport scheme is differently organized in Oscillatoria chalybea when compared to tobacco chloroplasts. Thus, the silicomolybdate reduction with water as the electron donor is sensitive to DCMU in these algae.

Carotenoids↗
PubMedDate not supplied

Evidence for nickel in the soluble hydrogenase from the unicellular green alga Scenedesmus obliquus.

Cultures of the green alga Scenedesmus obliquus were grown in the presence of either the chelating reagent EDTA or NiCl2 in various concentrations and assayed for hydrogenase catalyzed photohydrogen evolution after an anaerobic dark adaptation period. Cultivation of algae in the presence of 100 microM EDTA inhibited the formation of hydrogenase activity by 37%. After a cultivation of the cells in the presence of 5-20 microM NiCl2 photohydrogen evolution was increased by 20-40%. Addition of EDTA up to a final concentration of 1.5 mM had no effect on the activity of hydrogenase in cell-free hydrogenase preparations. Cultures grown in the presence of radioactive 63NiCl2 incorporated 63Ni in a parallel fashion to the cell growth. In radioactive labeled hydrogenase preparations a co-elution of radioactivity and hydrogenase activity could be observed using gel filtration chromatography.

Anaerobiosis↗
PubMedDate not supplied

Purification and characterization of cytochrome c6 from the unicellular green alga Scenedesmus obliquus.

Purification of a soluble cytochrome c6 from the unicellular green alga Scenedesmus obliquus by a simple and rapid method is described. The purification procedure includes ammonium sulfate precipitation and non-denaturating PAGE. The N-terminal sequence of the first 20 amino acids was determined and shows 85% similarity and 75% identity to the sequence of cytochrome c6 from the green alga Monoraphidium braunii. The ferrocytochrome shows typical UV/VIS absorption peaks at 552.9, 521.9 and 415.7 nm. The apparent molecular mass was estimated to be 12 kDa by SDS-PAGE. EPR-spectroscopy at 20 K shows resonances indicative for two distinct low-spin heme forms.

Amino Acid Sequence↗
PubMedDate not supplied

Chemical composition and biological activities of the Black Sea algae Polysiphonia denudata (Dillw.) Kutz. and Polysiphonia denudata f. fragilis (Sperk) Woronich.

The two investigated algae had almost identical sterol composition, but there were significant differences in the composition of the polar components and especially in the composition of the volatiles. P. denudata f. fragilis extracts possessed a stronger biological activity (antibacterial, antifungal and toxicity against Artemia salina). Despite the minute morphological differences between the two algae, we recommend P. denudata f. fragilis to be regarded as P. denudata subsp. fragilis.

1-Butanol↗
PubMed2005

Recent developments in the production of human therapeutic proteins in eukaryotic algae.

Antibody-based therapeutics have had great success over the last few years, and continue to be one of the fastest growing sectors of drug development. The efficacy and specificity of antibody-based drugs makes them ideal candidates for new drug development, but the specificity of these drugs comes from their complexity, and this complexity makes antibodies very expensive to produce. To address this problem, the authors have developed a system for the expression of recombinant proteins using the unicellular eukaryotic green algae, Chlamydomonas reinhardtii. As proof of concept, the authors have engineered microalgae to produce several forms of a human IgA antibody directed against herpes simplex virus. The expression of human monoclonal antibodies in C. reinhardtii offers an attractive alternative to traditional mammalian-based expression systems, as both the plastid and nuclear genomes are easily and quickly transformed, and the production of proteins in algae has an inherently low cost of capitalisation and production.

Algal Proteins↗
PubMed2001

The light environment and cellular optics of the snow alga Chlamydomonas nivalis (Bauer) Wille.

The alga Chlamydomonas nivalis lives in a high-light, cold environment: persistent alpine snowfields. Since the algae in snow receive light from all angles, the photon fluence rate is the critical parameter for photosynthesis, but it is rarely measured. We measured photon irradiance and photon fluence rate in the snow that contained blooms of C. nivalis. On a cloudless day the photon fluence rate at the snow surface was nearly twice the photon irradiance, and it can be many times greater than the photon irradiance when the solar angle is low or the light is diffuse. Beneath the surface the photon fluence rate can be five times the photon irradiance. Photon irradiance and photon fluence rate declined exponentially with depth, approximating the Bouguer-Lambert relationship. We used an integrating sphere to measure the spectral characteristics of a monolayer of cells and microscopic techniques to examine the spectral characteristics of individual cells. Astaxanthin blocked blue light and unknown absorbers blocked UV radiation; the penetration of these wavelengths through whole cells was negligible. We extracted astaxanthin, measured absorbance on a per-cell basis and estimated that the layer of astaxanthin within cells would allow only a small percentage of the blue light to reach the chloroplast, potentially protecting the chloroplast from excessive light.

Animals↗
PubMed2002

Heterologous expression and characterization of recombinant phytochrome from the green alga Mougeotia scalaris.

The full-length apoprotein (124 kDa) and the chromophore-binding N-terminal half (66 kDa) of the phytochrome of the unicellular green alga Mougeotia scalaris have been heterologously expressed in the methylotrophic yeast Pichia pastoris. Assembly with the tetrapyrrole phycocyanobilin (PCB) yielded absorption maxima (for the full-length protein) at 646 and 720 nm for red- and far-red absorbing forms of phytochrome (Pr and Pfr), respectively, whereas the maxima of the N-terminal 66 kDa domain are slightly blueshifted (639 and 714 nm, Pr and Pfr, respectively). Comparison with an action spectrum reported earlier gives evidence that in Mougeotia, as formerly reported for the green alga Mesotaenium caldariorum, PCB constitutes the genuine chromophore. The full-length protein, when converted into its Pfr form and kept in the dark, reverted rapidly into the Pr form (lifetimes of 1 and 24 min, ambient temperature), whereas the truncated chromopeptide (66 kDa construct) was more stable and converted into Pr with time constants of 18 and 250 min. Also, time-resolved analysis of the light-induced Pfr formation revealed clear differences between both recombinant chromoproteins in the various steps involved. The full-length phytochrome showed slower kinetics in the long milliseconds-to-seconds time domain (with dominant Pfr formation processes of ca 130 and 800 ms), whereas for the truncated phytochrome the major component of Pfr formation had a lifetime of 32 ms.

Base Sequence↗
PubMed2004

A monochromatic action spectrum for the photoinduction of the UV-absorbing mycosporine-like amino acid shinorine in the red alga Chondrus crispus.

To determine the action spectrum for photoinduction of the ultraviolet (UV)-absorbing mycosporine-like amino acid shinorine, specimens of the marine red alga Chondrus crispus were irradiated with monochromatic light of various wavelengths using the Okazaki large spectrograph at the National Institute for Basic Biology, Okazaki, Japan. Fluence response curves were determined for the wavelengths between 280 and 750 nm, by irradiating the algae with monochromatic light for 10 h, followed by 4 h of 25 micromol m(-2) s(-1) photosynthetically active radiation and 10 h darkness. Samples were taken after the second exposure interval. A linear correlation between fluence rate and accumulated shinorine concentration was detected for wavelengths between 350 and 490 nm in the fluence rate range of 20-30 micromol m(-2) s(-1), whereas there was no induction above 490 nm. Below 350 nm a decline in shinorine concentration could be observed at fluence rates above 30 micromol m(-2) s(-1), probably due to an inhibition of photosynthetic activity and a subsequent impairment of shinorine biosynthesis. The constructed action spectrum indicated that the photoreceptors mediating shinorine photoinduction might be an unidentified UV-A-type photoreceptor with absorption peaks at 320, 340 and 400 nm.

Amino Acids↗
PubMedDate not supplied

Microspectroscopy of the photosynthetic compartment of algae.

We performed microspectroscopic evaluation of the pigment composition of the photosynthetic compartments of algae belonging to different taxonomic divisions and higher plants. The feasibility of microspectroscopy for discriminating among species and/or phylogenetic groups was tested on laboratory cultures. Gaussian bands decompositions and a fitting algorithm, together with fourth-derivative transformation of absorbance spectra, provided a reliable discrimination among chlorophylls a, b and c, phycobiliproteins and carotenoids. Comparative analysis of absorption spectra highlighted the evolutionary grouping of the algae into three main lineages in accordance with the most recent endosymbiotic theories.

Eukaryota↗
PubMed2006

Tissue type matters: selective herbivory on different life history stages of an isomorphic alga.

Selective grazing by herbivores can have large effects on the population dynamics and community structure of primary producers. However, the ecological impacts of within-species herbivore preference for tissues of different phases (e.g., ploidy levels) or reproductive status remain relatively poorly known, especially among algae and other species with free-living haploid (gametophyte) and diploid (sporophyte) phases. We tested for herbivore selectivity among tissue types of the isomorphic (identical haploid and diploid free-living stages) red alga Mazzaella flaccida. Laboratory feeding assays demonstrated that the snail Tegula funebralis exhibited more than a threefold preference for gametophyte reproductive tissue over other tissue types, due to morphological differences. In contrast, the urchin Strongylocentrotus purpuratus did not distinguish as clearly between gametophytes and sporophytes; but it did prefer sporophyte reproductive to nonreproductive tissue, due to differences in water-soluble chemicals. Field surveys of grazer damage on M. flaccida blades were consistent with these laboratory preferences, with more damage found on gametophytes than sporophytes and reproductive than nonreproductive tissues. Differential fecundity can contribute to a skew in relative frequencies of phases in the field, and our results suggest that differential grazing by snails may contribute to this pattern and thus play a role in algal population biology.

Analysis of Variance↗