Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Chlorella”

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 667 records · Page 37Linked to original sources
PubMedDate not supplied

[Isolation and properties of the cell envelope of the green alga Chlorella fusca (author's transl)].

Chlorella cell envelopes were isolated by a mechanical procedure. The obtained morphological structure shown in an EM-picture has a mean density of rho=1.42. A characteristic chemical property of the envelope is the percentage of mono- and di-unsaturated C18-fatty acids which is considerably higher than that of intact cells. With 14C labelled sugars a selectivity of the hexose uptake could be shown, galactose uptake amounting only to about one fifth that of glucose and mannose. The uptake shows a temperature maximum. Part of the 14C registered after a 30 min uptake period is released by high concentration of unlabelled glucose, 20% are irreversibly fixed.

Cell Fractionation↗
PubMed1976

[Experimental role of the unicellular algae Prototheca and Chlorella (Chlorellaceae) in anti-cancer immunogenesis (murine BP8 sarcoma)].

Bacteria and Yeasts are able to induce, when inoculated into laboratory rodents, a general stimulation of defences by an immune process. We could estimate that unicellular algae would induce the same phenomenon because the chemical compounds of their walls are related to those of the precedings microorganisms specially to bacteria. Indeed, two Chlorellaceae, Prototheca segbwema and Chlorella pyrenoidosa are respectively protecting 78% and 82% CH3 mice against the sarcoma BP8 grafting.

Animals↗
PubMed2001

Ultrastructure of interaction in alginate beads between the microalga Chlorella vulgaris with its natural associative bacterium Phyllobacterium myrsinacearum and with the plant growth-promoting bacterium Azospirillum brasilense.

Chlorella vulgaris, a microalga often used in wastewater treatment, was coimmobilized and coincubated either with the plant growth-promoting bacterium Azospirillum brasilense, or with its natural associative bacterium Phyllobacterium myrsinacearum, in alginate beads designed for advanced wastewater treatment. Interactions between the microalga and each of the bacterial species were followed using transmission electron microscopy for 10 days. Initially, most of the small cavities within the beads were colonized by microcolonies of only one microorganism, regardless of the bacterial species cocultured with the microalga. Subsequently, the bacterial and microalgal microcolonies merged to form large, mixed colonies within the cavities. At this stage, the effect of bacterial association with the microalga differed depending on the bacterium present. Though the microalga entered a senescence phase in the presence of P. myrsinacearum, it remained in a growth phase in the presence of A. brasilense. This study suggests that there are commensal interactions between the microalga and the two plant associative bacteria, and that with time the bacterial species determined whether the outcome for the microalga is senescence or continuous multiplication.

Alginates↗
PubMedDate not supplied

[Activation of the chloroplast respiration increases chlorophyll fluorescence yield in Chlorella adapted to darkness at higher temperature].

A tenfold increase in chlororespiration during dark incubation of Chlorella perynoidosa Chick at high temperature doubled the initial chlorophyll fluorescence yield (F0). The presence of iodacetamide or unmetabolizable glucose analog 2-deoxy-D-glucose prevented increase in both chlororespiration and F0 yield. The rates of chlororespiration and F0 yield growth demonstrated a similar pattern of temperature dependence. Inhibition of electron transport between QA and plastoquinone prevented increase in F0 during dark respiration of the cells at high temperature. Apparently, a pool of plastoquinone was restored in the chlororespiratory chain during the dark incubation at 37.5-41 degrees C and plastoquinone exchanged electrons with QA. This is the cause of QA reduction and subsequent increase in F0 yield.

Adaptation, Physiological↗
PubMedDate not supplied

[Extracellular carbohydrates and polysaccharides of the algae Chlorella pyrenoidosa Chick S-39].

In the growing culture of the thermophilic alga Chlorella pyrenoidosa Chick S-39, the amount of extracellular carbohydrates in the medium reached 5-17% of their content in the cells and 20-40% of the total content of extracellular organic matter. Experiments with the enrichment and synchronous algal cultures showed that the accumulation of extracellular carbohydrates and polysaccharides in the media occurred due to their release from the cells, rather than to cell lysis, and depended on cell photosynthetic activity and reproduction. Chromatographic determination of free sugars revealed the presence of saccharose, glucose, and fructose in the culture medium. Extracellular carbohydrates in C. pyrenoidosa cultures were represented mainly by water-soluble polysaccharides containing galactose, mannose, arabinose, xylose, ribose, fucose, and rhamnose.

Arabinose↗
PubMed2004

[Isolation and effects on green alga Chlorella pyrenoidosa of algal-inhibiting allelochemicals in the macrophyte, Phragmites communis Tris].

Two fractions of secondary metabolites which inhibited the growth of green alga Chlorella pyrenoidosa, was isolated by several separation techniques from the ethanol extract of the macrophyte, Phragmites communis Tris. The EC50 of the two fractions on C. pyrenoidosa were 0.68 mg/L (the fraction of acidic solvent) and 2.65 mg/L (the fraction of alkaline solvent), respectively. Further purification of the allelochemicals in the acidic solvent by alkaline aluminum oxide column chromatography revealed that this fraction containing inhibiting allelochemicals and stimulating allelochemicals. The inhibiting allelochemicals showed more inhibitory effect and the EC50 was 0.50 mg/L. The result suggests that allelochemicals in P. communis can be used as an algae-inhibitor.

Chlorella↗
PubMed1977

[Purification, properties and quaternary structure of glutamine synthetase from Chlorella].

A highly purified preparation of glutamine synthetase from chlorella grown on a medium containing nitrate as a sole source of nitrogen, was isolated and characterized by disc-electrophoresis and analytical ultracentrifugation. The N-terminal amino acid of glutamine synthetase is glycine. The molecular weight of glutamine synthetase is 32.000; its activity in the presence of Mg2+ was 150 mkmol o-phosphate per min per mg protein. The molecular weight of subunits of the enzyme, equal to 53.000 was determined by disc-electrophoresis in polyacrylamide gel in the presence of sodium dodecyl sulfate. Electron microscopy of negatively contrasted enzyme preparations revealed 6 subunits in the enzyme molecule, arranged in a point symmetry group 32.

Chlorella↗
PubMed2004

[Sensitivity of Chlorella vulgaris to metribuzin, puma and alachlor].

The relative sensitivities of Chlorella vulgaris to three commonly used herbicides metribuzin, puma and alachlor were determined by toxicity tests of 96-h static exposures. The results showed that the toxicities of metribuzin and alachlor to C. vulgaris increased with exposure time, and the density of C. vulgaris decreased with increasing concentrations of these two herbicides in the test media. The maximum specific growth rate of C. vulgaris exposed to metribuzin (0.24 mgL x L(-1)) and alachlor (12.8 mg x L(-1)) was 12.38% and 31.58% of the control, respectively. At low concentration, puma stimulated C. vulgaris growth, but at high concentration, it inhibited the growth significantly. The maximum specific growth rate of C. vulgaris under 0.08 mg x L(-1) puma was 111.44% of the control, and the toxicity of puma declined with increasing exposure duration. The EC50 value of metribuzin, puma and alachlor was 0.021, 0.937, and 5.54 mg x L(-1), respectively. The relative sensitivities of C. vulgaris to the three herbicides decreased in the order of metribuzin, puma and alachlor. The chlorophyll a content of C. vulgaris decreased with the increasing concentrations of metribuzin, puma and alachlor.

Acetamides↗
PubMed2005

Suppression of glutathione S-transferase placental form-positive foci development in rat hepatocarcinogenesis by Chlorella pyrenoidosa.

The modifying effects of dietary administration of dried Chlorella pyrenoidosa powder (C. pyrenoidosa) on the development of glutathione S-transferase placental form-positive foci (GST-P-positive foci), which are putative preneoplastic lesions, in male F344 rats were investigated using a medium-term liver bioassay system. In rats given 10% C. pyrenoidosa in a basal diet, the number and area of GST-P-positive foci in the rat livers, which diethylnitrosamine (DEN) initiated and 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx) promoted, were significantly decreased compared with those fed a basal diet not containing C. pyrenoidosa. The inhibition percentage of the number and area of GST-P-positive foci > or =0.2 mm in diameter was 67.6 and 74.2%, respectively (p<0.01). Furthermore, C. pyrenoidosa significantly decreased the number of GST-P-positive foci induced by MeIQx alone. The inhibition percentage of the number of GST-P-positive foci <0.2 mm in diameter was 52% (p<0.01). These results suggest that C. pyrenoidosa has chemopreventive effects against hepatocarcinogenesis in rats. C. pyrenoidosa appears to be a promising chemopreventive agent for human liver neoplasia and carcinogenesis induced by heterocyclic amines such as MeIQx.

Animals↗
PubMedDate not supplied

[Influence of twovalent foreign cations on the uptake of zinc by Chlorella (author's transl)].

The influence of 10(-4) divalent cations on the uptake of labelled Zn in the concentration range 10(-5) to 5 x 10(-5) M into the interior of Chlorella fusca at 30 degrees C was measured during 75 min. The Zn absorbed on the surface or contained in the free space was removed by washing with EDTA. Corrections were applied for the loss in concentration due to surface adsorption, etc. The results were consistent with competitive inhibition of Zn uptake by the foreign ions. No allosteric inhibition was found. From the Lineweaver-Burk diagram, for uninhibited Zn, KM was found as 7 x 10(-6) M and Vmax as 8.3 x 10(-9) mol.min-1.g-1 algae. The inhibitor constants were: Mg 1.3 x 10(-5), Ca 4.3 x 10(-5), Co 4.3 x 10(-5), Ni 4.3 x 10(-5), Cd 1.3 x 10(-5) and Pb 9.4 x 10(-7) M. The values given for Km and the inhibitor constant refer to the velocities of uptake after 45 min.

Biological Transport↗
PubMed2005

Effects of selenium stress on photosynthetic pigment contents and growth of Chlorella vulgaris.

Changes in photosynthetic pigment and protein contents, growth and the spectral characteristics in Chlorella vulgaris in response to selenium stress were investigated. Carotenoids (beta-carotene and xanthophylls) and chlorophyll (Chl a and Chl b) contents in cells exposed to Se 50 mg/L increased primarily and decreased afterwards, while photosynthetic pigments in cells exposed to Se 800 mg/L decreased significantly. Chlorophyll (Chl) absorption peak at 693 nm and prominent Chl emission peak at 700 nm, weakened significantly after Se stress. The excitation spectra showed a decrease in excitation energy transfer efficiency in Se-stressed cells. Total soluble protein decreased after Se stress. The changes in total Se, Mg(2+), Ca(2+), K(+) and Na(+) concentrations in culture medium and cells were also determined by ICP-AES.

Calcium↗
PubMed2005

[Effects of Branchionus calyciflorus culture media filtrate on Microcystis aeruginosa, Scenedesmus obliquus and Chlorella vulgaris colony formation and growth].

To examine the possible information transfer by chemicals between zooplankton and algae, this paper studied the effects of Brachionus calyciflorus culture media filtrate on the colony formation and growth of Microcystis aeruginosa, Scenedesmus obliquus and Chlorella vulgaris. The results showed that the test filtrate could significantly promote the colony formation and population growth of S. obliquus, while no significant effect was observed on M. aeruginosa and C. vulgaris. The induced colony formation of S. obliquus increased its resistance to grazing, and thus, reduced the risk of its being grazed, which could be viewed as a kind of inducing defense. The accelerated growth of C. vulgaris and the toxin production of M. aeruginosa could also be interpreted as a defense mechanism against grazing. It maybe concluded that M. aeruginosa, S. obliquus and C. vulgaris could adopt different ecological strategies to resist the potential grazing by rotifer B. calyciflorus, and thus, to keep their population on a certain scale.

Animals↗
PubMed1975

Reduced nicotinamide adenine dinucleotide-nitrate reductase of Chlorella vulgaris. Purification, prosthetic groups, and molecular properties.

NADH:nitrate reductase (EC 1.6.6.1) from Chlorella vulgaris has been purified 640-fold with an over-all yield of 26% by a combination of protamine sulfate fractionation, ammonium sulfate fractionation, gel chromatography, density gradient centrifugation, and DEAE-chromatography. The purified enzyme is stable for more than 2 months when stored at minus 20 degrees in phosphate buffer (pH 6.9) containing 40% (v/v) glycerol. After the initial steps of the purification, a constant ratio of NADH:nitrate reductase activity to NADH:cytochrome c reductase and reduced methyl viologen:nitrate reductase activities was observed. One band of protein was detected after polyacrylamide gel electrophoresis of the purified enzyme. This band also gave a positive stain for heme, NADH dehydrogenase, and reduced methyl viologen:nitrate reductase. One band, corresponding to a molecular weight of 100, 000, was detected after sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme contains FAD, heme, and molybdenum in a 1:1:0.8 ratio. One "cyanide binding site" per molybdenum was found. No non-heme-iron or labile sulfide was detected. From a dry weight determination of the purified enzyme, a minimal molecular weight of 152, 000 per molecule of heme or FAD was calculated. An s20, w of 9.7 S for nitrate reductase was found by the use of sucrose density gradient centrifugation and a Stokes radius of 89 A was estimated by gel filtration techniques. From these values, and the assumption that the partial specific volume is 0.725 cc/g, a molecular weight of 356, 000 was estimated for the native enzyme. These data suggest that the native enzyme contains a minimum of 2 molecules each of FAD, heme, and molybdenum and is composed of at least three subunits.

Binding Sites↗
PubMed1990

Effect of Chlorella vulgaris extracts on murine cytomegalovirus infections.

The host-mediated antiviral effect of Chlorella vulgaris extracts (CVE) was evaluated in ICR mice against murine cytomegalovirus (MCMV) infection. Mice treated with 10 mg of CVE on days 3 and 1 before virus challenge survived lethal infection. The protective effect of CVE was shown by a decrease in the infectious viruses replicated in the target organs of CVE-treated ICR mice. CVE also protected mice from histopathological damage to the target organs due to MCMV infection. Both the serum interferon (IFN) level and 2'5'-oligoadenylate (2-5A) synthetase activity were elevated in CVE-treated and MCMV-infected mice, and were higher than those in the control mice. The natural killer (NK) activity of spleen cells, which is otherwise deteriorated by lethal MCMV infection, was remarkably augmented in CVE-treated mice. Neither virocidal nor virostatic activity of CVE on MCMV was seen in vitro. Thus, CVE-induced resistance against MCMV seems to be host-mediated. The protective effect correlated with the augmentation of NK activity of the spleen cells and serum IFN activity, which inhibited replication of MCMV in the target organs and subsequently saved the mice from death.

2',5'-Oligoadenylate Synthetase↗
PubMedDate not supplied

[Extraction of deuterated compounds from Chlorella sp. K. grown in D20].

A comparison of the three known methods made it possible to work out methods of complex extraction of deutero amino acids, deutero sugars and deutero vitamins from algae Chlorella sp. K., grown autotrophically in heavy water. An analysis of the isotopic composition of deutero amino acids by PMR indicates that treatment with HCl introduces 1H into side chains of some amino acids by chemical exchange (C2, 6H of tyrosine, C2H of histidine, rho-H of phenylalanin, beta-CH2-aspartate and gamma-CH2-glutamate. These exchanges made the amino acids convenient to be used as the substrates for the growth of heterotrophic selective deuterated organisms as a source of selective deuterated proteins.

Amino Acids↗
PubMed1990

Effect of cadmium on photosynthetic pigments in synchronously growing Chlorella cells.

Cadmium ions introduced at concentration of 30 ppm to the cultivation medium of synchronously growing Chlorella vulgaris decreased concentration of chlorophylls a and b, carotenes alpha and beta and lutein at various stages of the cell cycle, while at concentration of 1 ppm synthesis of the photosynthetic pigments was stimulated. The pigment content in the cadmium treated cells was related to the morphometrically determined changes in the size and shape of the cells.

Cadmium↗
PubMed1990

Immunological identification and quantification of light harvesting chlorophyll a/b protein of Chlorella protothecoides.

The alteration of photosynthetic membrane proteins in relation to the disappearance of pigments during the heterotrophic growth of Chlorella protothecoides was investigated. Chlorophylls and certain polypeptides associated with the LHC II disappeared after 50 hr of heterotrophic growth but the 24 kDa apoprotein constituting LHC II was not affected. Immunological analysis indicated that the chlorophylls and the light harvesting complex proteins of the thylakoid membranes are not tightly coupled and the latter is retained in its native form irrespective of the presence or absence of the former. The circumstantial evidence that the other photosynthetic membrane polypeptides are degraded along with the pigments due to increased proteolytic activity in the rapidly dividing heterotrophic cells indicate that chlorophyll synthesis is not a pre-requisite for the synthesis of the LHC II apoprotein.

Chlorella↗
PubMed1979

Observations on the mechanism of the reversible epimerization of GDP-D-mannose to GDP-L-galactose by an enzyme from Chlorella pyrenoidosa.

An enzyme fraction from the green alga Chlorella pyrenoidosa that catalyzes the reversible epimerization of guanosine 5'-diphosphate D-mannose to guanosine 5'-diphosphate L-galactose brings about the incorporation of tritium from tritium-labeled water into the hexosyl moieties of those sugar nucleotides. The hexoses were degraded by periodate oxidation whereby the tritium was found to be equally distributed between carbon atoms 3 and 5. That observation was taken to imply that the epimerizations proceed via ene-diol intermediates.

Carbohydrate Epimerases↗