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PubMedDate not supplied

Chlorella viruses encode multiple DNA methyltransferases.

The >320 kb dsDNA genomes of 16 viruses which infect Chlorella strain NC64A and 5 viruses infecting Chlorella strain Pbi were tested for their sensitivity/resistance to more than 80 DNA restriction endonucleases. From the known methylation sensitivities of these enzymes to site-specific 5-methylcytosine and N6-methyladenine DNA modifications, we deduce that the 16 NC64A viruses encode at least 13 different sequence-specific DNA methyltransferases and the 5 Pbi viruses encode at least 7 sequence-specific DNA methyltransferases. Each DNA methyltransferase has a 2 to 4 base pair DNA recognition sequence. Some individual viruses encode as many as ten different DNA methyltransferases, making these chlorella virus genomes among the most concentrated sources of DNA methyltransferase genes known.

Chlorella↗
PubMed2002

Chlorella virus pyrimidine dimer glycosylase excises ultraviolet radiation- and hydroxyl radical-induced products 4,6-diamino-5-formamidopyrimidine and 2,6-diamino-4-hydroxy-5-formamidopyrimidine from DNA.

A DNA glycosylase specific for UV radiation-induced pyrimidine dimers has been identified from the Chlorella virus Paramecium Bursaria Chlorella virus-1. This enzyme (Chlorella virus pyrimidine dimer glycosylase [cv-pdg]) exhibits a 41% amino acid identity with endonuclease V from bacteriophage T4 (T4 pyrimidine dimer glycosylase [T4-pdg]), which is also specific for pyrimidine dimers. However, cv-pdg possesses a higher catalytic efficiency and broader substrate specificity than T4-pdg. The latter excises 4,6-diamino-5-formamidopyrimidine (FapyAde), a UV radiation- and hydroxyl radical-induced monomeric product of adenine in DNA. Using gas chromatography-isotope-dilution mass spectrometry and y-irradiated DNA, we show in this work that cv-pdg also displays a catalytic activity for excision of FapyAde and, in addition, it excises 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua). Kinetic data show that FapyAde is a better substrate for cv-pdg than FapyGua. On the other hand, cv-pdg possesses a greater efficiency for the extension of FapyAde than T4-pdg. These two enzymes exhibit different substrate specificities despite substantial structural similarities.

Chlorella↗
PubMedDate not supplied

[Cytochrome f from Chlorella pyrenoidosa Pringsheim 82 T].

Cytochrome of the f type was isolated from the thermophilous autotrophic strain Chlorella pyrenoidosa Pringsheim 82T and purified on Sephadex G-75. The isolation procedure allowed a simultaneous production of glutamate dehydrogenase isoenzymes. From 100 g of Chlorella wet paste 100 to 120 nM of electrophoretically unicomponent protein with a molecular weight of 12,000 to 13,000 were isolated. The Chlorella cytochrome had an absorption spectrum in the visible light that was typical of the f type cytochromes.

Chlorella↗
PubMed2002

[Endosymbiotic bacteria and their relationship with chlorella in the ciliate Climacostomum virens].

Structure of cytoplasmic bacterial symbionts of chlorella-free ciliate Climacostomum virens has been investigated. It is shown that ciliates are not able to support simultaneously growth and duplication of two different symbionts--bacteria and chlorella. Cells of C. virens lost bacterial symbionts after an artificial infection with chlorella by microinjection. Competitive relationships between two endopionts are discussed.

Animals↗
PubMed2003

[Using chlorella and effective microorganisms to optimize aquatic ecological structure and to regulate water quality].

To optimize aquatic ecological structure and to regulate water quality, Chlorella vulgaris and effective microorganism were added to Exopalaemon carinicauda pond and fishponds. The results showed that after adding Chlorella vulgaris to the shrimp pond and fishpond, Chlorella vulgaris turned into a dominant species, and its amount was 16.92 and 4.76 times of CK. The zooplankton biomass reached to 4.32 mg.L-1 and 2.84 mg.L-1, increasing by 19.3% and 2.5%, compared with CK, respectively. Rhodospirillaceae, photosynthetic bacteria and yeast saccharomycete in the ponds could obviously change the composition, number, ratio, and biomass of the plankton (phytoplankton and zooplankton), and adjust aquatic chemical environment. The treatment of "Saccharomycete + Nitrifying bacteria" decreased the concentrations of NH4+ obviously, which was only 44% of CK. The BOD and COD in shrimp ponds were only 56.5% and 38.4% of CK. The treatment could increase the dissolved oxygen and primary production in the pond.

Animals↗
PubMed2004

[Photodegradation of 17beta-estradiol induced by Chlorella vulgaris].

The study showed that when exposed to high-pressure Hg-lamp (HPML, lambda(max) > or = 365 nm), and the concentration of Chlorella vulgaris was 4.0 x 10(10) cells x L(-1), the photodegradation rate of 17beta-estradiol could reach to 37%. When the concentration of Chlorella vulgaris was 4.2 x 10(10) cells x L(-1), the photodegradation of 1.5 x 10(-5) - 6.0 x 10(-5) mol x L(-1) 17beta-estradiol in aqueous solutions was pseudo-first order reaction. Increasing the initial concentration of 17beta-estradiol could lower its photodegradation rate. The influence of light intension and Chlorella vulgaris concentration on the photodegradation of 17beta-estradiol was also studied in this paper.

Biodegradation, Environmental↗
PubMed1991

Effect of chlorella on rats with iron deficient anemia.

In order to determine effects of iron deficiency on the living body, rats were given the iron deficient diet (Group 1, iron content, 0.32mg/100g), the complete diet added with iron (Group 5, iron content, 32.5mg/100g), the diet added with 1% chlorella (Group 2, iron content, 2.2mg/100g), the diet added with 5% chlorella (Group 3, iron content, 7.4mg/100g), or the diet added with 10% chlorella (Group 4, iron content, 13.9mg/100g). For the first 30 days, rats of all groups were given the iron deficiency diet to make them iron deficient, and were subsequently given the respective diet during the next 30 days to observe various changes in the conditions of rats. Following results were obtained. 1) When rats were reared for 30 days with the iron deficient diet, rats of these groups became anemic and their hemoglobin concentrations and hematocrit values lowered. Rats of Groups 3, 4 and 5 fed with the diets containing certain amounts of iron rapidly recovered, while the recovery of those of Group 2 fed with less iron content diet was delayed. Group 1 fed with the iron deficient diet showed no recovery. 2) Examination of effects of these diets on the rats body weight gains revealed that the growth of Groups 1 and 2 with iron deficiency was delayed notably (p less than 0.01) as compared with Group 5 and that of Group 3 was likewise restrained (p less than 0.05). The relative organ weights of all rats were examined. The liver weight in Groups 1, 2, 3, 4 was lower than that in Group 5, while that of the spleen in Groups 1 and 2 was higher than that in Group 5. 3) The Numbers of erythrocyte decreased in Groups 1 and 2 (p less than 0.01) and increased in Groups 3 and 4 (p less than 0.01) as compared with Group 5. There was no direct relation between the iron content in the diet and the number of leukocytes and their compositions. 4) Serum iron decreased remarkably in Groups 1 and 2 (p less than 0.01) but there were no intergroup differences in blood glucose value. 5) When osmotic fragility of erythrocyte membranes was expressed in term of NaCl concentration to indicate 50% hemolysis, Groups 1, 2 and 3 apparently increased their resistance as compared with Group 5 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia, Hypochromic↗
PubMed1987

Effect of dried, powdered Chlorella vulgaris on experimental atherosclerosis and alimentary hypercholesterolemia in cholesterol-fed rabbits.

The anti-lipidemic action and anti-atherosclerotic action of dried, powdered Chlorella vulgaris (CVP) were investigated using male Japanese White rabbits. A ten-week load of high-cholesterol diet remarkably increased serum total cholesterol and the beta-lipoprotein cholesterol levels in serum, causing aortic atheromatous lesion. In the Chlorella group which was administered a high-cholesterol diet containing 1% powdered Chlorella vulgaris, increase of total and beta-lipoprotein cholesterol level was suppressed. Further, the development of aortic atheromatous lesions was significantly inhibited. Clofibrate used as positive control in this experiment, did not show any inhibitory effect, either on the increase in serum lipid level or on the development of aortic atheromatous lesion.

Animals↗
PubMed1974

Metabolism of sulfoquinovosyl diglyceride in Chlorella pyrenoidosa by sulfoquinovosyl monoglyceride: fatty acyl CoA acyltransferase and sulfoquinovosyl glyceride: fatty acyl ester hydrolase pathways.

Cell-free preparations of Chlorella pyrenoidosa catalyze the transfer of the fatty acyl moiety of fatty acyl CoA derivatives to sulfoquinovosyl monoglyceride to form sulfoquinovosyl diglyceride. This reaction is stimulated by Triton X-100 concentrations of up to 0.6 mg/ml and has a pH optimum of 7.7. Similar Chlorella preparations catalyze the stepwise removal of both fatty acyl groups from sulfoquinovosyl diglyceride to form sulfoquinovosyl monoglyceride and then sulfoquinovosyl glycerol. This reaction is inhibited by both calcium and magnesium. The nonionic surfactant Triton X-100 inhibits the enzymatic deacylation at concentrations of less than 0.5 mg/ml but stimulates it at higher concentrations. The pH optimum for the deacylation of sulfoquinovosyl glycerides is 8.2, with little activity observed below pH 8. The enzymatic activities for both the transacylation and deacylation reactions are associated with a 30,000 g particulate fraction of Chlorella. Sulfoquinovosyl glycerol was found not to be an acceptor of the fatty acyl moiety of fatty acyl CoA derivatives. Methods are described for the preparation of sulfoquinovosyl monoglyceride, sulfoquinovose, and 3-sulfo-1,2-propanediol.

Acyltransferases↗
PubMed1994

On the molecular mechanism of the circadian clock. The 41,000 M(r) clock protein of Chlorella was identified as 3-phosphoglycerate kinase.

A 41,000 M(r) polypeptide of Chlorella exhibits a circadian rhythm in its synthesis and possesses characteristic features of a putative essential clock protein as was proposed by the coupled translation-membrane model. Purification of this polypeptide and a microsequencing analysis yielded a N-terminal sequence of 35 amino acids that showed no homology to known sequences that were thought to be involved in circadian rhythm such as the per gene of Drosophila and the frq gene of Neurospora. However, strong homology was observed to 3-phosphoglycerate kinase (PGK) of different organisms. The highest homology (83%) of this Chlorella sequence was found with the PGK of wheat chloroplast. PGK activity and the 41,000 M(r) polypeptide co-purified through differential centrifugation and gel filtration. These data, and comparison with the physical properties of other known PGK molecules, support the conclusion that the 41,000 M(r) polypeptide of Chlorella, a candidate for a putative essential clock protein, is 3-phosphoglycerate kinase.

Amino Acid Sequence↗
PubMed1993

Group I self-splicing introns in both large and small subunit rRNA genes of Chlorella.

We report the presence of Group I self-splicing introns in both nuclear small subunit (SSU) and large subunit (LSU) rRNAs of the unicellular green alga Chlorella ellipsoidea. The SSU intron (442 nt) was located at a position within the highly conserved helix 48 that was close to the 3' terminus of SSU rRNA: the position was exactly the same as previously reported for the Pneumocystis carinii Group I intron. The LSU intron (445 nt) was found in a highly conserved helix region (between positions 924-925) of LSU rRNA. Both introns can be folded into the secondary structures characteristic of Group I introns. The Chlorella introns self-spliced in vitro, yielding the typical Group-I intron splicing intermediates and products. Unlike the ordinary introns, however, splicing of the SSU intron was inhibited by high concentrations of monovalent cations at the second stage of splicing reaction. The Chlorella introns offer an opportunity to study the origin and evolution, physiological roles, and relationship between structure and splicing activity of Group I self-splicing introns.

Base Sequence↗
PubMed1995

Isolation and characterization of hardening-induced proteins in Chlorella vulgaris C-27: identification of late embryogenesis abundant proteins.

Hardening-induced soluble proteins of Chlorella vulgaris Beijerink IAM C-27 (formerly Chlorella ellipsoidea Gerneck IAM C-27) were isolated and purified by two-dimensional high-performance liquid chromatography (2D-HPLC) on an anion-exchange column, with subsequent reversed-phase chromatography. Some of the proteins were resolved by SDS-PAGE, characterized by amino-terminal sequencing and identified by searching for homologies in databases. Separation of the soluble proteins during the hardening of Chlorella by a combination of 2D-HPLC and SDS-PAGE revealed that at least 31 proteins were induced or increased in abundance. Of particular interest was the induction after 12 h of a 10-kDa protein with the amino-terminal amino acid sequence AGNKPITEQISDAVGAAGQKVG and the induction after 6 h of a 14-kDa protein with the amino-terminal sequence ALGEESLGDKAKNAFEDAKDAVKDAAGNVKEAV. The amino-terminal sequences of these proteins indicated that they were homologous to late embryogenesis abundant (LEA) proteins. Furthermore, the level of a 22-kDa protein also increased after 12 h. The amino-terminal sequence of this protein, AAPLVGGPAPDFTAAAVFD, indicated that it was homologous to thioredoxin peroxidase.

Amino Acid Sequence↗
PubMed1993

Characterization of the terminal inverted repeats and their neighboring tandem repeats in the Chlorella CVK1 virus genome.

A unique group of large icosahedral viruses that infect a unicellular green alga (Chlorella sp. NC64A) were isolated from freshwater sources in Japan. These viruses contain a linear double-stranded DNA (dsDNA) genome with hairpin ends. A physical map was constructed for the genomic DNA of CVK1 (Chlorella virus isolated in Kyoto, no. 1) by pulsed-field gel electrophoresis of restriction fragments. The nucleotide sequences around both termini of the CVK1 DNA revealed the presence of inverted terminal repeats (ITR) of approximately 1.0 kb. Adjacent to the ITR, unique sequence elements of 10 to 20 bp were directly repeated 20 to 30 times in tandem array. Several copies of these repeat elements were deleted in virus mutants that were occasionally generated from Chlorella cells that were in a putative CVK1 carrier state. These repeats might represent a hot spot of rearrangement in the CVK1 genome.

Base Sequence↗
PubMed1989

Wastewater nutrient removal by Chlorella pyrenoidosa and Scenedesmus sp.

Two different species of photosynthetic microalgae, Chlorella pyrenoidosa and Scenedesmus sp., were grown in settled and activated sewage filtrates at two different inoculum sizes, aimed to reduce nutrient load from wastewater. Higher growth rates were recorded in cultures with higher inoculum size, and algal cells usually grew better in settled sewage than in activated sewage. As algae started to grow and multiply, both nitrogen and phosphorus content in wastewater decreased significantly. The removal rate was rapid during the first week of growth and more than 2/3 of wastewater N and P was reduced. After the initial period, the removal rate slowed down. At the end of this study, more than 80% of total-P and inorganic N present in settled sewage were reduced but such removal efficiency was lower in activated sewage. In general, high inoculum size of algal cells provided more N and P removal than low inoculum, and Chlorella cells performed better than Scenedesmus. These results suggest that cultivation of Chlorella seems to be one of the feasible methods to reduce the amount of nitrogen and phosphorus entering the nearby coastal water, thus preventing the eutrophication problem. It is also clear that algal ponds with high inoculum size might be more suitable to be installed as a secondary rather than a tertiary treatment process.

Journal Article↗
PubMed1990

The comparison of growth and nutrient removal efficiency of Chlorella pyrenoidosa in settled and activated sewage.

The microscopic green alga, Chlorella pyrenoidosa was grown in settled and activated sewage under two different culture systems, batch and semi-continuous. Good growth was obtained in both types of wastewater and the algal production was comparable to and even higher than that found in commercial Bristol medium. The semi-continuous culture supported more growth than the batch system. There was a close relationship between algal growth and the amount of nutrient removed from both settled and activated sewage. A more rapid drop in NH(4)(+)-N was found in settle rather than activated sewage. The NH(4)(+)-N of settled sewage dropped from its initial 27 to 5 mg litre(-1) in both culture systems. On the other hand, the NO(3)(-)-N of activated sewage started to decrease from Day 2 onwards and the final NO(3)(-)-N concentration was less than 1 mg litre(-1) (over 90% removal efficiency). The amount of total inorganic nitrogen being reduced due to algal culture was similar in both types of sewage. The changes of phosphate content followed the same trend in both sewage, the P concentration increased slightly in the first two days then decreased, especially in the semi-continuous cultures. The final ortho-P in the sewage treated by Chlorella in semi-continuous culture was less than 5 mg litre(-1) (about 62% reduction). Such removal efficiency was slightly lower than those reported in previous studies. In general, the semi-continuous algal culture appeared to be a more suitable and efficient way for wastewater treatment than the batch system. With respect to the total reduction of wastewater inorganic N and P by means of Chlorella cells, there was no significant difference between settled and activated sewage.

Journal Article↗
PubMed1988

Immunomodulation by a unicellular green algae (Chlorella pyrenoidosa) in tumor-bearing mice.

A unicellular algae, Chlorella pyrenoidosa, was used as a biological response modifier. In C57BL/6(B6), C3H/He and DDD/1 mice, both intraperitoneal or oral administrations of autoclaved Chlorella cells or heat-extracted substance were carried out every other day for 10 days before mouse mammary carcinoma (MM-2) or Ehrlich ascites cells were transplanted into the peritoneal cavity. In case of mouse leukemia cells (EL-4), subcutaneous transplantation was carried out. All control mice died within 20 days after each tumor cell transplantation, while 73.3-80% of the treated groups survived over 60 days in the combination of MM-2 vs. C3H/He and EL-4 vs. B6, respectively. The cytotoxic activities against tumor cells, that were abolished by treatment with anti-Thyl.2 monoclonal antibody plus complement, were evidenced in the experimental host. Since Chlorella cells and derivatives showed no indication of direct in vitro cytotoxicity to either tumor or mouse spleen cells, the antitumor effects documented may be mediated by host immune response.

Adjuvants, Immunologic↗
PubMed2003

Analysis of the DNA joining repertoire of Chlorella virus DNA ligase and a new crystal structure of the ligase-adenylate intermediate.

Chlorella virus DNA ligase is the smallest eukaryotic ATP-dependent DNA ligase known; it suffices for yeast cell growth in lieu of the essential yeast DNA ligase Cdc9. The Chlorella virus ligase-adenylate intermediate has an intrinsic nick sensing function and its DNA footprint extends 8-9 nt on the 3'-hydroxyl (3'-OH) side of the nick and 11-12 nt on the 5'-phosphate (5'-PO4) side. Here we establish the minimal length requirements for ligatable 3'-OH and 5'-PO4 strands at the nick (6 nt) and describe a new crystal structure of the ligase-adenylate in a state construed to reflect the configuration of the active site prior to nick recognition. Comparison with a previous structure of the ligase-adenylate bound to sulfate (a mimetic of the nick 5'-PO4) suggests how the positions and contacts of the active site components and the bound adenylate are remodeled by DNA binding. We find that the minimal Chlorella virus ligase is capable of catalyzing non-homologous end-joining reactions in vivo in yeast, a process normally executed by the structurally more complex cellular Lig4 enzyme. Our results suggest a model of ligase evolution in which: (i) a small 'pluripotent' ligase is the progenitor of the much larger ligases found presently in eukaryotic cells and (ii) gene duplications, variations within the core ligase structure and the fusion of new domains to the core structure (affording new protein-protein interactions) led to the compartmentalization of eukaryotic ligase function, i.e. by enhancing some components of the functional repertoire of the ancestral ligase while disabling others.

Adenosine Monophosphate↗
PubMed1994

Growth at Low Temperature Mimics High-Light Acclimation in Chlorella vulgaris.

Structural and functional alterations to the photosynthetic apparatus after growth at low temperature (5[deg]C) were investigated in the green alga Chlorella vulgaris Beijer. Cells grown at 5[deg]C had a 2-fold higher ratio of chlorophyll a/b, 5-fold lower chlorophyll content, and an increased xanthophyll content compared to cells grown at 27[deg]C even though growth irradiance was kept constant at 150 [mu]mol m-2 s-1. Concomitant with the increase in the chlorophyll a/b ratio was a lower abundance of light-harvesting polypeptides in 5[deg]C-grown cells as observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and confirmed by western blotting.The differences in pigment composition were found to be alleviated within 12 h of transferring 5[deg]C-grown cells to 27[deg]C. Furthermore, exposure of 5[deg]C-grown cells to a 30-fold lower growth irradiance (5 [mu]mol m-2 s-1) resulted in pigment content and composition similar to that in cells grown at 27[deg]C and 150 [mu]mol m-2 s-1. Although both cell types exhibited similar measuring-temperature effects on CO2-saturated O2 evolution, 5[deg]C-grown cells exhibited light-saturated rates of O2 evolution that were 2.8-and 3.9-fold higher than 27[deg]C-grown cells measured at 27[deg]C and 5[deg]C, respectively. Steady-state chlorophyll a fluorescence indicated that the yield of photosystem II electron transport of 5[deg]C-grown cells was less temperature sensitive than that of 27[deg]C-grown cells. This appears to be due to an increased capacity to keep the primary, stable quinone electron acceptor of photosystem II (QA) oxidized at low temperature in 5[deg]C- compared with 27[deg]C-grown cells regardless of irradiance. We conclude that Chlorella acclimated to low temperature adjusts its photosynthetic apparatus in response to the excitation pressure on photosystem II and not to the absolute external irradiance. We suggest that the redox state of QA may act as a signal for this photosynthetic acclimation to low temperature in Chlorella.

Journal Article↗