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1.
Utilization Modes of Inorganic Carbon for Photosynthesis in Various Species of Chlorella 总被引:5,自引:0,他引:5
Rates of CO2 and HCC3 fixation in cells of various Chlorellaspecies in suspension were compared from the amounts of 14Cfixed during the 5 s after the injection of a solution containingonly 14CO2 or H14CO3. Results indicated that irrespectiveof the CO2 concentration during growth, Chlorella vulgaris 11h and C. miniata mainly utilized CO2, whereas C. vulgaris C-3,C. sp. K. and C. ellipsoidea took up HCO3 in additionto CO2. Cells of C. pyrenoidosa that had been grown with 1.5%CO2 (high-CO2 cells) mainly utilized CO2, whereas those grownwith air (low-CO2 cells) utilized HCO3 in addition toCO2. Cells that utilized HCO3 had carbonic anhydrase(CA) on their surfaces. The effects of Diamox and CA on the rates of CO2 and HCO3fixation are in accord with the inference that HCO3 wasutilized after conversion to CO2 via the CA located on the cellsurface. CA was found in both the soluble and insoluble fractions;the CA on the cell surface was insoluble. Independent of the modes of utilization, the apparent Km (NaHCO3)for photosynthesis was much lower in low-CO2 cells than in high-CO2ones. The fact that the CA in the soluble fraction in C. vulgarisC-3 was closely correlated with the Km(NaHCO3) indicates thatsoluble CA lowers the Km.
1 Dedicated to the late Professor Joji Ashida, one of the foundersand first president of the Japanese Society of Plant Physiologists.
4 On leave from Research and Production Laboratory of Algology,Bulgarian Academy of Sciences, Sofia. (Received September 14, 1982; Accepted March 1, 1983) 相似文献
2.
Chlorella vulgaris 11h cells grown in air enriched with 4% CO2(high-CO2 cells) had carbonic anhydrase (CA) activity whichwas 20 to 90 times lower than that of algal cells grown in ordinaryair (containing 0.04% CO2, low-CO2 cells). The CO2 concentrationduring growth did not affect either ribulose 1,5-bisphosphate(RuBP) carboxylase activity or its Km for CO2. When high-CO2 cells were transferred to low CO2 conditions,CA activity increased without a lag period, and this increasewas accompanied by an increase in the rate of photosynthetic14CO2 fixation under 14CO2-limiting conditions. On the otherhand, CA activity as well as the rate of photosynthetic 14CO2fixation at low 14CO2 concentrations decreased when low-CO2cells were transferred to high CO2 conditions. Diamox, an inhibitor of CA, at 0.1 mM did not affect photosynthesisof low-CO2 cells at high CO2 concentration (0.5%). Diamox inhibitedphotosynthesis only under low CO2 concentrations, and the lowerthe CO2 concentration, the greater was the inhibition. Consequently,the CO2 concentration at which the rate of photosynthesis attainedone-half its maximum rate (Km) greatly increased in the presenceof this inhibitor. When CO2 concentration was higher than 1%, the photosyntheticrate in low-CO2 cells decreased, while that in high-CO2 cellsincreased. Fractionation of the low-CO2 cells in non-aqueous medium bydensity showed that CA was fractionated in a manner similarto the distribution of chlorophyll and RuBP carboxylase. These observations indicate that CA enhances photosynthesisunder CO2-limiting conditions, but inhibits it at CO2 concentrationshigher than a certain level. The mechanism underlying the aboveregulatory functions of CA is discussed.
1This work was reported at the International Symposium on PhotosyntheticCO2-Assimilation and Photorespiration, Sofia, August, 1977 (18).Requests for reprints should be addressed to S. Miyachi, RadioisotopeCentre, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan. (Received December 11, 1978; ) 相似文献
3.
Role of Carbonic Anhydrase in Photosynthesis of Blue-Green Alga (Cyanobacterium) Anabaena variabilis ATCC 29413 总被引:2,自引:0,他引:2
The affinity for NaHCO3 (CO2) in photosynthesis of Anabaenavariabilis ATCC 29413 was much higher in the cells grown underordinary air (low-CO2 cells) than in those grown in air enrichedwith 24% CO2 (high-CO2 cells) (pH 8.0, 25?C). Ethoxyzolamide(50 µM) increased the Km(NaHCO3 in low-CO2 cells aboutnine times (from 14.3 to 125), while the maximum rate of photosynthesisdecreased about 20%. When high-CO2 cells were transferred tolow-CO2 conditions, carbonic anhydrase (CA) activity increased,while Km(NaHCO3) in photosynthesis decreased from 140 to 30µM within about 5 h. The addition of CA to the suspensionof both high- and low-CO2 cells enhanced the rates of photosyntheticO2 evolution under CO2-limiting conditions. The rate of 14CO2fixation was much faster than that of H14CO3 fixation.The former reaction was greatly suppressed, while the latterwas enhanced by the addition of CA. These results indicate thatthe active species of inorganic carbon utilized for photosynthesiswas free CO2 irrespective of the CO2 concentration given duringgrowth. It is suggested that CA plays an active role in increasingthe affinity for CO2 in photosynthesis of low-CO2 cells of thisblue-green alga. (Received January 24, 1984; Accepted October 22, 1984) 相似文献
4.
Form of inorganic carbon utilized for photosynthesis in Chlorella vulgaris 11 h cells 总被引:2,自引:0,他引:2
The rate of photosynthetic 14CO2 fixation in Chlorella vulgaris11h cells in the presence of 0.55 mM NaH14CO3 at pH 8.0 (20?C)was greatly enhanced by the addition of carbonic anhydrase (CA).However, when air containing 400 ppm 14CO2 was bubbled throughthe algal suspension, the rate of 14CO2 fixation immediatelyafter the start of the bubbling was suppressed by CA. Theseeffects of CA were observed in cells which had been grown inair containing 2% CO2 (high-CO2 cells) as well as those grownin ordinary air (containing 0.04% CO2, low-CO2 cells). We thereforeconcluded that, irrespective of the CO2 concentration givento the algal cells during growth, the active species of inorganiccarbon absorbed by Chlorella cells is free CO2 and they cannotutilize bicarbonate. The effects observed in the high-CO2 cellswere much more pronounced than those in the high-CO2 cells.This difference was accounted for by the difference in the affinityfor CO2 in photosynthesis between the high- and low-CO2 cells. (Received May 19, 1978; ) 相似文献
5.
Cells of Dunaliella tertiolecta which had been grown in ordinaryair (low-CO2 cells) had high carbonic anhydrase (CA) activityon the cell surface and mainly utilized HCO3 for photosynthesis.When CA activity on the cell surface was inhibited by Diamoxor subtilisin, the cells utilized CO2. When bovine CA was added,the subtilisin-treated low-CO2 cells utilized mainly HCO3.When grown in air containing 2% CO2, the cells had low CA activityon the cell surface, and preferred CO2 to HCO3. Kineticanalysis of these results indicated that low-CO2 cells of D.tertiolecta absorb CO2 which was converted from HCO3via the CA located on the cell surface. (Received June 29, 1985; Accepted October 9, 1985) 相似文献
6.
Time courses of photosynthetic 14CO2 fixation and its simulationare presented for Chlorella cells grown under low CO2 concentration(low-CO2 cells) and subsequently exposed to 0.2 mM NaH14CO3or 130 ppm 14CO2 in the presence or absence of carbonic anhydrase(CA) in the suspending medium. It was shown that Chlorella cells utilized only free CO2 whenNaHCO3 was given in the presence or absence of CA, or when CO2was bubbled in the absence of CA. However, the present simulationindicated that both CO3 and HCO3 were utilized when CO2was given in the presence of CA. Based on these results, weconcluded that 1) Chlorella cells absorb only free CO2 and 2)this gas is provided to algal cells in two ways, i.e., by directand indirect CO2 supply. Usually, the dissolved CO2 is directlyutilized by the algal cells (direct supply of CO2). However,when the concentration of dissolved CO2 is extremely low andwhen there is CA, CO2 reconverted from HCO3 is also utilizedby Chlorella cells (indirect supply of CO2). The utilizationof HCO3 indicated by the above simulation was explainedby the indirect supply of CO2. We further assumed that the indirectsupply of CO2 to ribulose 1,5-bisphosphate carboxylase occursmainly in the chloroplasts of low-CO2 cells containing highCA. Thus, under low CO2 concentrations, low-CO2 cells can carryout more efficient CO2 fixation than high-CO2 cells, resultingin the lower apparent Km(CO2).
3Department of Biology, Faculty of Science, Niigata University,Niigata, Japan. (Received April 2, 1980; ) 相似文献
7.
Imamura Machiko; Tsuzuki Mikio; Shiraiwa Yoshihiro; Miyachi Shigetoh 《Plant & cell physiology》1983,24(3):533-540
The effect of carbonic anhydrase (CA) on time courses of photosynthetic14C incorporation in the presence of 14CO2 or NaH14CO3 was studiedwith cells of Chlamydomonas reinhardtii which had been grownunder ordinary air (low-CO2 cells) or air enriched with 4% CO2(high-CO2 cells). Experimental data obtained at 20°C andpH 8.0 suggested that the major form of inorganic carbon utilizedby high-CO2 cells was CO2, while that utilized by low-CO2 cellswas HCO3. The cell suspension showed CA activity which was comparableto that observed in the sonicate of cells. Both activities werehigher in low-CO2 cells than in high-CO2 cells. The mechanism by which HCO3 is utilized by low-CO2 cellsof C. reinhardtii is discussed.
3Present address: Department of Biology, Faculty of Science,University of Niigata, Niigata 950-21, Japan. (Received August 4, 1982; Accepted January 19, 1983) 相似文献
8.
The increase in carbonic anhydrase (CA) activity and the decreasein apparent Km(CO2) for photosynthesis induced by reducing CO2concentration during the growth of Chlorella vulgaris 11h cellswere followed under different temperatures. Both changes wereaccelerated by raising the temperature and reached an optimumat 3237?C. When the CO2 concentration was lowered from3 to 0.04%, the rate of photosynthetic O2 evolution at limitingCO2 concentrations increased and reached a stationary levelafter 3 h. Under such conditions, the concentration of CO2 dissolvedin the algal suspension decreased logarithmically (t1/2=10 min)and reached a concentration in equilibrium with 0.04% CO2 inair after ca. 2 h. When high-CO2 cells grown with 3% CO2 in air were transferredto various lower CO2 concentrations, CA activity and apparentKm(CO2) for photosynthesis changed depending on the CO2 concentration.The CO2 concentration which gives one-half the maximum valuefor Km(CO2) and one-half minimum value foi CA activities wasabout 0.5%. The inverse relationship observed for the changesin CA activity and the affinity for CO2 in photosynthesis supportsthe theory that CA loweres the apparent Km(CO2) for photosynthesisin Chlorella vulgaris 11h. (Received August 27, 1984; Accepted February 8, 1985) 相似文献
9.
In cells of cyanobacterium Anabaena variabilis grown under ordinaryair (low-CO2 cells), the transport of both CO2 and HCO3was significantly enhanced by Na+. This effect was pronouncedas the external pH increased. When low-CO2 cells were treatedwith an inhibitor of carbonic anhydrase (CA), only CO2 transportbut not HCO3 transport, was inhibited. The initial rateof photosynthetic carbon fixation as a function of the concentrationof internal inorganic carbon (IC) was practically the same irrespectiveof whether CO2 or HCO3 was externally supplied. Theseresults suggest that IC is actively transported through theplasma membrane in a form of HCO3 probably by some transporterand that the transmembrane Na+ gradient is involved in thisIC transport system. Free CO2 may be hydrated by CA to HCO3and then transported to the cells by this transporter. On the other hand, CO2 is actively taken up by cells grown withair containing 5% CO2 (high-CO2 cells) though the enhancingeffect of Na+ was much smaller in high- CO2 cells than in low-CO2cells. The initial rate of fixation as a function of internal IC concentrationindicated that the rate of the carboxylation reaction of accumulatedIC is higher in I0W-CO2 cells than in high-CO2 cells. The studieswith ethoxyzolamide indicated that even in low-CO2 cells, CAdoes not function inside Anabaena cells. These results suggestthat inside the low-CO2 cells of Anabaena, some mediator(s)facilitates the transport of IC to RuBPCase. (Received January 23, 1987; Accepted April 24, 1987) 相似文献
10.
Active uptake of inorganic carbon by Chlorella saccharophila is not repressed by growth in high CO2 总被引:1,自引:0,他引:1
Regulation of transport of dissolved inorganic carbon (DIC)in response to CO2 concentration in the external medium hasbeen compared in two closely-related green algae, Chlorellaellipsoidea and Chlorella saccharophila. C. ellipsoidea, whengrown in high CO2, had reduced activities of both CO2 and transport and DIC transport activitieswere increased after the cells had acclimated to air. However,high CO2-grown C. saccharophila had a comparable level of photosyntheticaffinity for DIC to that of air-grown C. ellipsoidea and thiswas accompanied by a capacity to accumulate high internal concentrationsof DIC. The high photosynthetic affinity and the high intracellularDIC accumulation did not change in cells grown in air exceptthat the occurrence of external carbonic anhydrase (CA) in air-grownC. saccharophila stimulated the intracellular DIC accumulationin the absence of added CA. These data indicate that activeDIC transport is constitutively expressed in C. saccharophila,presumably because this alga is insensitive to the repressiveeffect of high CO2 on DIC transport. This strongly supportsthe existence of a direct sensing mechanism for external CO2in Chlorella species, but also indicates that external CA isregulated independently of DIC transport in Chlorella species. Key words: Carbonic anhydrase, Chlorella, CO2-insensitive, DIC transport, wild type 相似文献
11.
Transfer of algal cells of Chlorella regularis from 3% CO2 inair into ordinary air in the light increased external carbonicanhydrase (CA) activity as well as photosynthetic affinity forCO2 by several-fold within 2 h. Since no noticeable differencewas observed in CA activity between intact cells and cell homogenates,CA seemed to be mainly localized on the cell surface. Changesin CA activity and K?(CO2) of photosynthesis were not observedin the dark. CA induction was 50%-inhibited by incubation with10 µM DCMU during adaptation of high-CO2 cells to air,whereas it was considerably suppressed when high-CO2 cells preincubatedwith DCMU in the light for 6 h or without DCMU in the dark for24 h were used. The change in K?(CO2) of photosynthesis wasonly slightly affected by DCMU. Uncoupler like carbonylcyanide-m-chlorophenyl-hydrazone(CCCP) and inhibitors of mitochondrial respiration (KCN plussalicylhydroxamic acid) suppressed CA induction during adaptationof high-CO2 cells to low CO2 conditions. These results suggest that photosynthesis is not essential forCA induction in Chlorella regularis when some amounts of photosyntheticproducts are previously stored in the cells and respirationis active. A decrease in K?(CO2) of photosynthesis during adaptationfrom high to low CO2 was mostly independent on photosynthesis.However, light is essential for both phenomena. (Received July 16, 1990; Accepted January 21, 1991) 相似文献
12.
In Dunaliella tertiolecta, D. bioculata and D. viridis the activitiesof phosphoenolpyruvate carboxylase and carbonic anhydrase werehigher in the cells grown in ordinary air (low-CO2 cells) thanin those grown in air enriched with 15% CO2 (high-CO2cells), whereas in Porphyridium cruentum R-1 there was no differencein phosphoenolpyruvate carboxylase activity between these twotypes of cells. Apparent Km(NaHCO3) values for photosynthesisin low-CO2 cells of all species tested were smaller than thosein high-CO2 cells. Most of the 14C was incorporated into 3-phosphoglycerate,sugar mono- and di-phosphates during the initial periods ofphotosynthetic NaH14CO3 indicating that both types of cellsin D. tertiolecta are C3 plants. (Received May 27, 1985; Accepted June 25, 1985) 相似文献
13.
Intracellular accumulation of inorganic carbon (Ci) and itsfixation in photosynthesis were investigated using siliconeoil layer filtering centrifugation technique with the cellsof Chlorella vulgaris 11h grown under ordinary air. Both CO2and HCO3 were transported into the cells from the reactionmedium and accumulated in the cells, but the rate of transportwas much faster for the former than the latter. 14C-fixationfrom the total transported Ci was much more efficient when CO2was added in the external medium than when HCO3 was added.This indicates that CO2 and HCO3 were not converted tothe common compound in the cells during the initial period ofphotosynthesis. Accumulation of Ci into the cells was much lesssusceptible to low temperature than its fixation. Accumulationof Ci was also observed in the dark. Ethoxyzolamide, an inhibitorof carbonic anhydrase (CA), inhibited the fixation of accumulatedCO2 in the cells, suggesting that CA enhanced the supply ofCO2 to the reaction site of ribulose bisphosphate carboxylasein the stroma. Mechanism for transport and fixation of Ci duringphotosynthesis in low-CO2 cells of C. vulgaris 1lh was proposedfrom these results. (Received March 19, 1986; Accepted June 26, 1986) 相似文献
14.
The maximum rate of photosynthetic 14CO2 fixation (Vmax) aswell as the concentration of CO2 at which the rate of photosynthetic14CO2 fixation attains one-half its maximum velocity (Km) inChlorella vulgaris 11h cells was strongly dependent on the concentrationof CO2 continuously provided during the algal growth. The Vmax (µmoles 14CO2 fixed/ml pcv?min) and Km (% CO2)of the algal cells which had been grown in air containing 4%CO2 (by volume) were ca. 10 and 0.150.17, while thosein the cells which had been grown in ordinary air (containing0.04% CO2) were 7 and 0.050.06, respectively. When the concentration of CO2 in the bubbling gas was loweredfrom 4 to 0.04% during the algal growth, their photosynthetickinetics attained the respective lower steady levels after 510hr. On the other hand, when the photosynthetic kinetics weredetermined 24 hr after raising the concentration of CO2 from0.04 to 4%, the Vmax and Km-values were found to have alreadyattained the respective higher levels. (Received October 15, 1976; ) 相似文献
15.
Carbonic anhydrase (CA) activity was detected in homogenatesfrom Anabaena variabilis ATCC 29413, M-2 and M-3, but not inthe suspension of the intact cells. Activity was higher in cellsgrown in ordinary air (low-CO2 cells) than in those grown inair enriched with 24% CO2 (high-CO2 cells). Fractionationby centrifugation indicated that the CA from A. variabilis ATCC29413 is soluble, whereas both soluble and insoluble forms existin A. variabilis M-2 and M-3. The addition of dithiothreitoland Mg2 $ greatly decreased the CA activity of A. variabilisATCC 29413. The specific activity of the CA from A. variabilis ATCC 29413was increased ca. 200 times by purification with ammonium sulfate,DEAE-Sephadex A-50 and Sephadex G-100. Major and minor CA peaksin Sephadex G-100 chromatography showed respective molecularweights of 48,000 and 25,000. The molecular weight of the CAdetermined by polyacrylamide disc gel electrophoresis was 42,000?5,000.The activity of CA was inhibited by ethoxyzolamide (I50=2.8?10-9M), acetazolamide (I50=2.5?10-7 M) and sulfanilamide (I50=2.9?10-6M). (Received January 5, 1984; Accepted April 26, 1984) 相似文献
16.
Tsuzuki Mikio; Gantar Miroslav; Aizawa Katsunori; Miyachi Shigetoh 《Plant & cell physiology》1986,27(4):737-739
The cells of Dunaliella tertiolecta grown under ordinary air(low-CO2 cells) had a well developed pyrenoid with many morestarch granules than those grown under air enriched with CO2(high-CO2 cells). The chloroplast was located close to the plasmamembranein low-CO2 cells, while that in high-CO2 cells was located inthe inner area of the cells. Chloroplast envelope was electronicallydenser in low-CO2 cells than in high-CO2 cells, while the oppositeeffect of CO2 was observed for the plasmamembrane.
2On leave from Institute of Biology, University of Novi Sad,Novi Sad, Yugoslavia. (Received November 7, 1985; Accepted March 5, 1986) 相似文献
17.
A method is described for the rapid separation of carbonic anhydrase(CA) isozymes by cellulose acetate membrane electrophoresisin which CA activity is detected using the pH-indicating dye,bromcresol purple. This method can detect bovine erythrocyteCA in a 0.3 mm3 sample applied at a concentration of 100 ngcm3 (total of 30 pg applied) while at higher concentrationsthree isozymes were observed. It was found, using a potentiometrictechnique, that intact cells of Anabaena flos-aquae (Cyanophyceae)and Chlorella ellipsoidea had no detectable activity while C.saccharophila and Chlamydomonas reinhardtii (Chlorophyceae)had external CA activity. CA activity of the extracts suggestedthe presence of internal CA in all species. After electrophoresisit was found that C. saccharophila and C. reinhardtii had twoisozymes while A. flos-aquae and C. ellipsoidea had only a singledetectable band. Spinach had up to five detectable isozymesthat were difficult to resolve. Incubation of spinach extractwith the CA inhibitor ClO4 (500 mol m3) inhibitedCA activity by 90% using the potentiometric technique, but afterelectrophoresis had no detectable effect. This technique isuseful in identifying isozymes that are substantially differentin electrical charge and in monitoring CA isozyme activity duringenzyme purification. Key words: Carbonic anhydrase, isozymes, cyanobacteria, microalgae, spinach 相似文献
18.
19.
Antibody was raised against Porphyridium carbonic anhydrase(CA) which was electrophoretically recovered from the gel afterSDS-polyacrylamide slab gel electrophoresis (SDS-PAGE) of thepartially purified enzyme. The antiserum reacted with CA ofPorphyridium, but not with that of Chlamydomonas reinhardtii.Even though the antiserum did not react with CA from P. cruentumR-l in Ouchterlony's double immunodiffusion, it blocked theenzyme activity in the presence of 1% Nonidet P-40 and 1% TritonX-100. After Western blotting and enzyme-linked immunostaining(ELIS), only one band which reacted with the antiserum was detectedin the extract of low-CO2 cells (grown under ordinary air) ofP cruentum, while no significant band was detected in that ofhigh-CO2 cells (grown under air enriched with 15% CO2).Immunogold electron microscopy of low-CO2 cells of P. cruentumR-l using this antibody revealed that most of the CA was localizedin the chloroplast, with some in the cytoplasm. No specificbinding of gold particles was observed in the high-CO2 cells.
1Present address: National Institute for Basic Biology, Myodaiji,Okazaki 444, Japan (Received May 18, 1987; Accepted September 7, 1987) 相似文献
20.
GEHL KATHARINA A.; COOK CATHERINE M.; COLMAN BRIAN 《Journal of experimental botany》1987,38(7):1203-1210
The carbon dioxide compensation point of the unicellular greenalga, Chloretla saccharophila, was determined in aqueous mediumby a gas chromatographic method. Compensation points decreasedmarkedly from 63 cm3 m3 at an external pH of 4.0 to 3.2cm3 m3 at pH 8.0 and were not affected by the O2 concentrationof the medium. The calculated CO2 concentration required tosupport the half-maximum photosynthetic rate of the algal cellsranged from 6.0 mmol m3 at an external pH of 60 to 1.5mmol m3 at pH 8.0 and these values were not affectedby O2 concentration. The Km(CO2) of nbulose-l,5-bisphosphatecarboxylase isolated from cells grown either at pH 4.0 or pH8.0 was determined to be 64 mmol m3. These results indicatethat loss of CO2 by photorespiration does not occur in C. saccharophilacells at acid pH and the disparity between the apparent affinityfor CO2 of the intact cells and that of the carboxylase indicatesthe operation of a CO2 concentrating mechanismin this alga at acid pH. Key words: Acidophilic alga, bicarbonate transport, Chlorella saccharophila, compensation point, CO2 affinity, PH, RuBP carboxylase 相似文献