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1.
Cell wall lytic activity was detected in Chlorella ellipsoidea Gernick IAM C-27 using the [14C]-labeled cell wall as substrate. The highest activity was obtained at pH 8. and the solubilized product was a polysaccharide of high molecular weight. The lytic activity appeared to be a protease and did not hydrolyse glycosidic bonds of the cell wall polysaccharides. The activity probably solubilizes the cell wall by cleaving the peptide bonds that interconnect the polysaccharides of the cell wall.  相似文献   

2.
For the elucidation of the isotope effect on cell functionsof deuterium (D) incorporated into cell constituents, alterationsin the heat response of D-exchanged Chlorella ellipsoidea (D-Chlorella)were investigated. D-Chlorella cells obtained by culture inmedium that contained 60 mol% D2O were assayed for their responseto heat in H2O medium to rule out the solvent isotope effectof D2O. Upon heating at 41–45?C, the heat sensitivityof D-Chlorella was greater than that of ordinary (H-Chlorella)cells; at 43?C, the heat sensitivity of D-Chlorella was 1.5–1.6times higher than that of H-Chlorella. For the induction ofresistance to heating, preheating of the cells at a lower temperaturethan that used for heat treatment was effective in the caseof both D- and H-Chlorella. However, the optimum temperaturefor preheating of D-Chlorella (34?C) was lower than for H-Chlorella(36–37?C). With preheating at 34?C, heat-shock proteins(HSPs), in particular proteins of 62 and 79 kDa, were inducedsimilarly in both types of cell. However, the gel-electrophoreticpatterns of HSPs induced at 37?C were differed somewhat betweenD- and H-Chlorella. These results suggest that the responseof cells to heat, in particular the induction of resistanceto heating and the synthesis of HSPs, was altered by deuterationof cell constituents. (Received June 11, 1990; Accepted November 24, 1990)  相似文献   

3.
The photosynthetic metabolism of carbon in fully deuteratedcells of Chlorella ellipsoidea C-27 (D-Chlorella), obtainedby culture in medium prepared with 100 mol% D2O, was characterizedby examining the activities of several enzymes and the levelsof metabolic regulators in a comparison with those of ordinarycells (H-Chlorella). The cellular content of starch in D-Chlorellawas more than twice that in H-Chlorella, whereas those of sucroseand glucose were significantly lower in D-Chlorella. Deuterationof Chlorella caused marked alterations in the activities ofenzymes involved in starch metabolism. There was a significantdecrease in the activity of phosphorylase, a catabolic enzyme,and a significant increase in the activity of starch synthase,an anabolic enzyme. These alterations are probably responsiblefor the increase in the amount of starch in cells. By contrast,no marked changes were observed in the activities of enzymesand the levels of metabolic inhibitors that are involved inthe synthesis of sucrose. It seems likely, therefore, that thedecrease in the amount of sucrose in D-Chlorella was causedmainly by a deficiency in sources of carbon in the cytoplasm,as a consequence of an increase in levels of starch in chloroplasts. (Received May 13, 1992; Accepted December 1, 1992)  相似文献   

4.
Rhythmical changes in carbonic anhydrase activity(CA) and inphotosynthesis were observed during the cell cycle of Chlorellaellipsoidea C-27 synchronized at various concentrations of dissolvedCO2 (dCO2 with a regime of 16 h of light and 8 h of darkness.At a constant low concentration of dCO2 (11 {diaeresis}M), intracellularCA activity showed obvious fluctuations with a peak at 8 h afterthe initiation of illumination, while extracellular CA activity,located on the cell surface, showed only minor fluctuationsalthough the activity was as high as the maximum activity ofintracellular CA. In contrast, obvious changes in the activitiesof intra- and extracellular CA activities were not observedat a high concentration of dCO2 (520 {diaeresis}M). The ratioof photosynthetic activity at limiting versus saturating concentrationsof dCO2, which is indicative of the affinity of cells for CO2,showed clear rhythmical changes during the cell cycle and theratio was higher in low-CO2 cells than in high-CO2 cells. Thechanges in the ratio seemed to reflect the changes in CA activity. When the cells that had been synchronized under high CO2 conditionswere transferred to low CO2 conditions at any given stage inthe cell cycle, CA activity was induced in every case but thecapacity for induction of CA was greater in young cells thanin mature cells. This result suggests that the capacity of cellsto induce CA over the course of the cell cycle is closely relatedto endogenous aging of the cell. (Received August 29, 1988; Accepted December 28, 1988)  相似文献   

5.
Protoplasts from Chlorella ellipsoidea IAM C-27 were rapidlyobtained by enzymatic digestion with a mixture of ChitosanaseKI, mixed glycosidases, and a cell wall-lytic enzyme found inthe cell homogenate of C-27 cells. The formation of naked protoplastswas demonstrated by electron microscopy. (Received December 18, 1991; Accepted May 12, 1992)  相似文献   

6.
Cell wall lytic activity was detected in the culture medium and cell wall of 1AM Chlorella ellipsoidea C-87. The enzymes of both fractions had their highest activity at pH 5. The lytic activity bound to the cell wall consisted of a polysaccharide releasing enzyme, an exo-type enzyme releasing disaccharide, and glucosidase; but only the polysaccharide releasing enzyme was solubilized by lithium chloride. A polysaccharide releasing enzyme with a molecular weight around 40 kDa was isolated from the culture medium. Hemicellulose is degraded by the polysaccharide releasing enzyme, and the rigid wall by the exo-type enzyme.  相似文献   

7.
The effect of cyanide on ammonia and urea metabolism was studiedwith intact cells of Chlorella ellipsoidea Gerneck, a greenalga which apparently lacks urease. Ammonia uptake was inhibited more readily by cyanide than wasurea uptake. Urea uptake was stimulated by lower concentrationsof cyanide. The addition of cyanide caused the formation ofammonia from some cellular nitrogenous compounds. In the presenceof exogenously added urea, the molar ratio of ammonia accumulatedin the medium to urea taken up exceeded 2.0 as the cyanide concentrationincreased. However, the molar ratio of ammonia actually producedfrom urea nitrogen to urea taken up was less than 1.35 at anyconcentration of cyanide tested. In the presence of higher concentrationsof cyanide, the rate of incorporation of 15N into amino acidsfrom 15N-urea was higher than that from 15N-ammonium sulfate. The results suggest that Chlorella ellipsoidea possesses a pathwaythrough which urea nitrogen is assimilated directly withouta preliminary breakdown to ammonia. (Received October 18, 1976; )  相似文献   

8.
The ratio of the extracellular to the intracellular activityof carbonic anhydrase (CA) in cells of Chlorella ellipsoideaC-27, adapted to low levels of CO2 for 24 h (low-CO2 cells),was about one to one. Treatment of intact cells with PronaseP inactivated about one-half of the extracellular CA activitywithout affecting photosynthetic activity. The CA activity incell homogenates and in cell-wall ghosts liberated during celldivision was completely inactivated by the same treatment. Pretreatmentwith Glycosidase mix, Chitosanase and Macerozyme enhanced theinactivation of the CA activity in intact cells. These resultssuggest that extracellular CA is evenly distributed throughoutthe whole cell-wall region. The apparent K1/2 for dissolved inorganic carbon (DIC) in low-CO2cells doubled when extracellular CA was inactivated by treatmentwith Pronase P, but the K1/2 obtained was still one-half ofthat in high-CO2 cells. Photosynthetic 14CO2-fixation in low-CO2cells was enhanced by acetazolamide, whereas H14CO3-fixationwas suppressed. The results suggest that CO2 is a dominant substrateutilized by cells and that HCO3 is utilized after conversionto CO2. The present results show that both intracellular andextracellular CA contribute to the increase in affinity forDIC during photosynthesis in low-CO2 cells of Chlorella ellipsoideaC-27. (Received May 7, 1990; Accepted July 18, 1990)  相似文献   

9.
Superoxide dismutase and chilling injury in Chlorella ellipsoidea   总被引:7,自引:0,他引:7  
The relationship between superoxide dismutase (SOD) and chilling injury was examined in chilling-sensitive and chilling-resistant strains of Chlorella ellipsoidea. The sensitive strain contained less SOD than the resistant strain. Moreover, all of the SOD in the sensitive strain was the H2O2-sensitive, iron-containing SOD, whereas most of the SOD in the resistant strain was the H2O2-resistant, manganese-containing SOD. Illumination further enhanced the disparity in SOD content between the sensitive and resistant strains since the SOD in the former declined during illumination, whereas the SOD in the latter strain did not. It was possible to elevate the SOD content of the sensitive strain and to increase the proportion of MnSOD by prior growth in the presence of 50 microM paraquat. The SOD content of the cultures after 5 h of illumination at 4 degrees C fell in the order sensitive strain less than paraquat-induced sensitive strain less than resistant strain. The resistance of these cultures to chilling injury was related to SOD content. This was the case whether resistance was assessed in terms of growth rate after chilling, bleaching of chlorophyll during chilling, or loss of viability during chilling. It thus appears likely that O2- is an agent of chilling injury.  相似文献   

10.
Cells of Chlorella ellipsoidea Gerneck (IAM C-27) were synchronouslygrown under a 28-hr light-14-hr dark regime at 25°C. Thealgal cells at different stages during the cell cycle were hardenedat 3°C for 48 hr. The survival rate of hardened cells wasmaximum (70%) at the L2 stage(ripening phase) in the life cycle.The average cell volume of L2 cells increased during hardening,but the process of nuclear division scarcely advanced. The hardinessof L2 cells increasedwith prolongation of hardening time upto 48 hr. Their viability decreased upon increasing the ratof cooling and lowering the final freezing temperature. Butthe hardened cells, which had been prefrozen stepwise, showeda survival rate above 50% even at –196°C when thawedrapidlyin a bath at 25°C. Although L2 cells were somewhathardened in the dark, illumination was the more effective whenused with bubbling gas. Under illumination, bubbling of 1% CO2-airincreased the hardiness more than CO2-free air, but in the dark,this relation was reversed. The hardiness was lowest with nitrogengas bubbling under both conditions. (Received December 3, 1975; )  相似文献   

11.
A circular DNA molecule was isolated from chloroplasts of Chorella ellipsoidea. The DNA had a buoyant density of 1.695 grams per cubic centimeter (36% GC) and a contour length of 56 micrometers (175 kilobase pairs). The restriction endonuclease analysis gave the same size. Agarose gel electrophoretic patterns of chloroplast DNA digested by several restriction endonucleases were also presented. The digestion by the restriction enzymes, HpaII, MspI, SmaI, and XmaI revealed no appreciable methylation at CG sites in chloroplast DNA.  相似文献   

12.
The sterol composition of C. ellipsoidea was markedly changed when this alga was grown in the presence of 1 μg/g triparanol. Triparanol appears to inhibit the removal of 14α-methyl group, the second alkylation at C-24, Δ7-reductase, and Δ8 → Δ7-isomerase. The effect of triparanol in Chlorella is much more diversified than the specific effect originally assigned to it in animals.  相似文献   

13.
Chlorella is an attractive organism for complex recombinant protein production because of its eukaryotic characteristics and low cost for large-scale culture. Protoplasts of C. ellipsoidea were transformed with a vector containing the flounder growth hormone gene (fGH) under the control of the cauliflower mosaic virus 35S promoter, and the phleomycin resistance Sh ble gene under the control of the Chlamydomonas RBCS2 gene promoter. The presence of introduced DNA was first determined by PCR amplification of both the fGH and Sh ble genes from genomic DNA isolated from transformants and fGH protein expression was detected by immunoblot analysis. Over 400 μg of fGH protein expression per one liter culture containing 1 × 108 cells/ml was estimated by ELISA. Stable integration of introduced DNA was confirmed by Southern blot analysis of genomic DNA digested with restriction enzymes. The introduced DNA and fGH expression were detected after seven successive transfers in media devoid of phleomycin, but stably remained in the presence of the antibiotic. Flounder fry fed on the transformed Chlorella revealed a 25% growth increase after 30 days of feeding. Received March 26, 2001; accepted July 10, 2001.  相似文献   

14.
24-Dihydrolanosterol-[2-3H] was converted to cholesterol in Chlorella ellipsoidea but ergost-5-enol, poriferasterol, clionasterol were not labelled. The absence of the necessary 24(25) double bond precursor eliminates the possibility of C28 and C29 sterol synthesis. However, it was confirmed that 24-dihydrolanosterol was metabolized by Ochromonas malhamensis to give cholesterol, brassicasterol, and poriferasterol.  相似文献   

15.
Eight bacterial strains identified as P1, P2, Y1, Y2, W1, W2, G, and R were isolated from a long-term laboratory culture of the green alga Chlorella ellipsoidea. Although it is unknown how these bacterial strains have been maintained with the C. ellipsoidea culture, all appeared to promote the growth of C. ellipsoidea. Co-inoculation of each bacterial strain with C. ellipsoidea resulted in 0.5–3 times greater algal growth than that of C. ellipsoidea alone. The most effective bacterium (i.e., strain P1) was selected and further characterized. Biochemical analysis and transmission electron microscopy revealed that strain P1 is closely related to the genus Brevundimonas. Sequence analysis of the 16S rRNA of strain P1 showed 99.9 and 99.4% nucleotide sequence identity to that of B. nasdae and B. vesicularis, respectively. In addition to the growth promotion of C. ellipsoidea by strain P1, the growth of strain P1 was also significantly enhanced by co-culturing with C. ellipsoidea, indicating a symbiotic relationship between the bacterium and alga. Scanning electron microscopy showed the direct adhesion of strain P1 cells to the surface of C. ellipsoidea cells, as well as the development of abundant crinkles on the surface of co-cultured C. ellipsoidea cells. Handling editor: J. Padisak  相似文献   

16.
A rapid induction of sulfate transport was observed in the greenalga Chlorella ellipsoidea during sulfur-limited growth. Bothaffinity and Vmax increased about five-fold within 6 h of transferringcells from Bold's basal medium with 350 µM MgSO4 to sulfur-deficientBold's medium. High affinity sulfate transport was induced within15 min and reached maximum rate within 3 h of transferring cellsto sulfur-deficient condition, indicating that a new, high-affinity-sulfatetransport system is induced by sulfur starvation in C. ellipsoidea.Eadie-Hofstee plots of initial rates of sulfate uptake indicatedthat the K of sulfur-starved cells was about 17 µM. Bothsulfur-starved and unstarved cells grown in air had a Vmax of1.5 times higher than that of high-CO2 grown cells. Sulfatetransport was completely inhibited by 30 µM CCCP or 800µMKCN both in the light and the dark but transport in the lightwas not inhibited by 20 µM DCMU. Treatment with 50 µMor 500 µM vanadate caused 50% inhibition of uptake. Therate of sulfate uptake in the dark was twice that in the lightand was stimulated by low pH. These results suggest that thesulfate transport system in C. ellipsoidea is operated by protonsymport across the plasmamembrane which is partially mediatedby P-type ATPase and that these systems depend exclusively onenergy derived from oxidative phosphorylation in the mitochondria. (Received June 28, 1995; Accepted August 8, 1995)  相似文献   

17.
The nucleotide sequence of hiC12, isolated as a cDNA clone of hardening-induced Chlorella (hiC) genes, was identified. The clone encodes a late embryogenesis abundant (LEA) protein having six repeats of a 11-mer amino acid motif, although in a slightly imperfect form. To overexpress the hiC61) and hiC12 genes, their coding regions were PCR amplified and subcloned into a pGEX-1lambdaT vector. The HIC6 and HIC12 proteins were expressed as GST fusion proteins in E. coli, then purified. The two HIC proteins were found to be effective in protecting a freeze-labile enzyme, LDH, against freeze-inactivation. On a molar concentration basis, they were about 3.1 x 10(6) times more effective in protecting LDH than sucrose and as effective as BSA. Cryoprotection tests with five kinds of chain-shortened polypeptides, synthesized based on the 11-mer amino acid motif of the HIC6 protein showed that the cryoprotective activity decreased with a decrease in the repeating units of the 11-mer motif. In fact, cryoprotective activities of three kinds of single 11-mer amino acids were very low even at high concentrations. All the results suggested that the sufficiently repeated 11-mer motif is required for the cryoprotective activities of Chlorella LEA proteins.  相似文献   

18.
Chlorella ellipsoidea Gerneck (IAM C-27) was synchronously grown and cells at an intermediate stage in the ripening phase of the cell cycle were hardened at 3 C for 48 hours. At various times of hardening, the cells were pulse-labeled for 4 minutes with [14C]NaHCO3 in the light or with [14C]glucose in the dark, and the incorporation rate of 14C into total lipids was determined. A high incorporation rate of [14C]NaHCO3 at zero time of hardening decreased after 6 hours. In the next 15 hours, a distinct increase was noted. This increase occurred prior to the development of frost hardiness. Cycloheximide completely inhibited both the increase and the development, and 3-(3,4-dichlorophenyl)-1,1-dimethylurea remarkably lowered the high incorporation rate at zero time. The incorporation rate of [14C]glucose increased along with hardiness in the dark. These results suggest that the major site of lipid synthesis shifts from chloroplasts to a cytoplasmic system during hardening of Chlorella.  相似文献   

19.
Summary An EcoRI 2.7 kbp fragment from Chlorella ellipsoidea chloroplast DNA (cpDNA) cloned in YIp5 was shown to promote autonomous replication in Saccharomyces cerevisiae. The fragment was localized in the small single copy region close to the inverted repeat. The ARS activity (autonomously replicating sequences in yeast) was found to be confined within a subclone of a ca. 300 bp HindIII fragment. Sequence analysis of this fragment revealed its high AT content and the presence of several direct and inverted repeats and a few elements that were related to the yeast ARS consensus sequence. Electron microscopic studies revealed that this sequence did not coincide with the primary replication origin of chloroplast DNA. The functioning of this sequence as a possible origin of plasmid replication in vivo is discussed. This is the first report on Chlorella cpDNA sequence. re]19850821 rv]19851211 ac]19851216  相似文献   

20.
Chlorella ellipsoidea cells at an intermediate stage in theripening phase of the cell cycle were hardened at 3?C. Oligomycin(OGM) and 3-(3,4-dichiorophenyl)-1,1-dimethylurea (DCMU) addedduring hardening in the light inhibited the development of frosthardiness, suggesting that mitochondria and chloroplasts wereinvolved in the hardening process. The O2-uptake activity in unhardened cells increased duringhardening in the light while the O2-evolution activity decreased,when these activities were measured at 25?C. The increase inO2 uptake was suppressed by OGM and DCMU and the decrease inO2 evolution was stimulated by OGM. While the algal hardinessin the dark was very limited, the addition of glucose duringhardening in the dark caused a remarkable development of frosthardiness. These results suggest that mitochondria and chloroplastsclosely interact at low temperature, and the former plays aprincipal role in the hardening process and the latter servesas substrate-donor in the light. The O2 evolution in cells which survived freezing was remarkablydecreased by freeze-thawing while the O2 uptake was hardly affected.The freeze-injured chloroplasts were repaired during the followingincubation. OGM inhibited the repair of freeze-injured chloroplasts.From the results, mitochondria seem to change their membranesinto a structure hardier than chloroplasts, and ATP synthesizedby mitochondria seems to be essential for the repair of freeze-injuredchloroplasts. 1 Present address: Department of Public Health, Faculty of Medicine,Kyushu University, Maidashi 3-1-1, Higashiku, Fukuoka 812, Japan. (Received November 9, 1977; )  相似文献   

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