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1.
- In the early stage of CO2-fixation by Thiobacillus thiooxidans,which was incubated aerobically in the presence of sulfur, mostpart of the fixed carbon was found in the phosphate ester fraction.
- The fixation was inhibited by NaF, picolinic acid, PCMB, azide,dipyridyl, o-phenanthroline, monoiodoacetic acid, and arsenite,each in the concentration range where the sulfur oxidation wasnot affected strongly.
- The crude extract of this organismcould fix CO2 in the presenceof ATP, R-5-P and Mg++. Most partof the fixed carbon was foundin PGA.
- The crude extract showedthe CO2-fixation coupled with the H2S-oxidationin the presenceof ADP.
- An appreciable reduction of PGA could not be detectedin thepresence of reducing systems, involving TPNH and DPNH.
2.
Metabolism of some sulfur-containing substances was studiedin a copper-resistant strain of yeast (R), its parent strain(P) and respiratory-deficient(RD) mutants from them. The resultsobtained are as follows:
- Using sulfate, sulfite and thiosulfate as sulfur sources, Rproducedmore H2S than P, and both of these had the activityhigher than their RD mutants. All of them produced a large amountof H2S from cysteine, but only little from methionine, cysteinesulfinic acid and S-sulfocysteine.
- From sulfite and thiosulfate,P and R produced more H2S inaerobicthan in anaerobic condition.With sulfate and cysteine, however,H2S production did not differunder those conditions.
- In both P and R, the sulfate-to-sulfiteand sulfite-to-sulfidereactions were remarkably lowered byiron and zinc deficiencies.But the cysteine-to-sulfide reactionwas not affected by themetal-deficiencies.
- H2S productionfrom sulfate was remarkably depressed by highconcentrationsof pantothenate.
- Rates of reaction steps on a plausible pathway from sulfatetosulfide and to organic sulfur compounds areestimated forthe strainsused. R is characterized by its largecapacity ofthe reaction step from sulfate to sulfite, and excessivesulfitethus formed is liberatedas sulfide not by the way ofcysteine.
3.
- Using intact cells of Chlorella, the effects of CO2 on thelevelsof oxidized and reduced forms of DPN and TPN in the lightandin the dark were investigated.
- It was found that the light-inducedchanges of the DPNH-levelwere not affected by the presenceor absence of CO2. On theother hand, the light-induced increaseof TPNH was suppressedin the presence of CO2 and the levelof TPNH which was raisedon illumination in the absence of CO2was lowered by the provisionof CO2.
- On the basis of thesefindings, it was concluded that TPNH,but not DPNH, is participating,in some way, in the mechanismof photosynthesis.
- Discussionswere made on the difference in the sites of participationofTPNH and of the photogenic reducing agent (R) in the pathofcarbon in photosynthesis.
4.
Oxygen enhanced photosynthetic 14CO2 fixation in Anacystis nidulanscells. Results obtained under different conditions revealedthe following properties of the oxygen enhancement:
- The enhancement was most significant at ca. 10% O2. Furtherincrease in oxygen concentration decreased the enhancing effect.The rate under 100% O2 was equivalent to or a little higherthan that under N2 gas.
- b) With the increase in CO2 concentration,the magnitude ofthe enhancing effect decreased. No oxygen enhancementwas observedwhen the CO2 concentration. was raised to 9,000ppm.
- c) The enhancement was observed only at high light intensities.No enhancement was observed when the rate of photosynthesiswas limited by light intensity.
- Ribulose 1,5-diphosphate (RuDP)carboxylase activity was demonstratedin the extract obtainedfrom A. nidulans cells. We also foundthat the RuDP carboxylaseactivity in this extract was competitivelyinhibited by oxygen.
- Based on the above-mentioned results, the possible mechanismunderlying the observed enhancing effect of oxygen was discussed.
5.
- Using intact cells of Chlorella ellipsoidea, investigationswere made on the effects of some SH-reagents (IAA, CMB and arsenite)upon various reactions pertaining to the primary photogenicagent (designated by R) formed in the mechanism of photosynthesis.
- The pre-illumination experiments using 14CO2 as a tracer haveled us to the inference that (i) the process of photochemicalformation of R is inhibited by IAA, that (ii) the spontaneousdecay of R in the dark is markedly accelerated by CMB and arsenite,but not at all affected by IAA, and that (iii) the participationof R in the cyclic path of carbon leading to the fixation ofCO2 is not affected by IAA and CMB.
- Based on the assumptionthat R is a reducing agent, it was discussedthat the fact mentionedunder (iii) is incompatible with theidea that the reductionof PGA to triose phosphate be the soleor rate-determining reductivestep in the cyclic path of carbonin photosynthesis.
- The possibilitythat R may have a functional SH-group (s) wasinvoked to accountfor the observation that the decay of R inthe dark was markedlyaccelerated by CMB and arsenite.
6.
- In the presence of NADP+ and Mg++, the bundle sheath strandsisolated from corn (Zea mays) leaves by cellulase treatmentsdecarboxylated malate in the light at an initial rate (200 µmoles/mgchl.hr), which was sufficient to account for photosyntheticCO2 fixation in intact leaves. This rate gradually slowed downand then stopped. The final level of the malate decarboxylatedwas approximately equal to the amount of NADP+ added.
- Rapidand continued decarboxylation of malate was observed whenNADP+,3-phosphoglyceric acid and ATP (and Mg++) were addedtogether.The addition of ADP instead of ATP showed a similareffect.Light did not show any effect on the malate decarboxylationin the presence of ATP or ADP.
- When malate was added to thebundle sheath strands in the presenceof exogenous NADP+ NADP+was rapidly reduced. The reductionstopped after 2 min when,73% of the added NADP+ was reduced.The further addition of3-phosphoglyceric acid and ATP broughtabout a decrease in theNADPH-level, which rose again to attaina new steady level.
- The transfer of radioactivity from (1-14C-3-phosphoglycericacid to dihydroxyacetone phosphate in the bundle sheath strandsin the presence of ATP and NADP+ was greatly enhanced by theaddition of malate.
- In the presence of ribose 5-phosphateand ATP, the rate of 14C-transferfrom (4-14C)-malate to theintermediates of the reductive pentosephosphate cycle was equalto that of 14CO2 fixation in the light.
7.
- Changes in capacities for reducing nitrate, nitrite and hydroxylaminecaused by provision or depletion of various nitrogen sourceswere investigated with a nitrogen fixing blue-green alga, Anabaenacylindrica, and adaptive nature of these reducing system wasdemonstrated.
- It was found that, under light-aerobic conditions,nitrate-and nitrite- reducing systems were induced by nitrateor nitritebut not by N2 ammonia and glutamate. On the otherhand, theactivity of enzymes pertaining to hydroxylamine reductionwasstimulated equally by nitrate, nitrite and N2. The latteractivitywas suppressed markedly in the presence of ammoniaor glutamate.
- Adaptive formation of nitrite reducing systemis completelyinhibited by chloramphenicol, a potent inhibitorof proteinsynthesis. No formation was also observed under theanaerobiccondition or in the dark.
- On the basis of thesefindings, a tentative scheme for pathwaysof nitrate reductionand nitrogen fixation in Analaena cylindricawas proposed.
8.
- Evidence was obtained which supports the hypothesis that thefirm colonies of Nostoc verrucosum, but not the softer onesof N. commune, can accumulate phosphate from the environmentby non-active means.
- This accumulation of phosphate was reducedby pre-treating thecolonies with chelating agents, whilst thepresence of CaCl2in the medium led to an increase.
9.
- Cytochromes a1590, b560, c1554 and c1552 were isolated andpurifiedfrom a strain of Acetobacter suboxydans. The proceduresusedwere described in detail.
- The main cytochrome band at550-560 mµ in intact cellssplitted at liquid air temperatureinto two bands, 551 mµ(strong) and 559 mµ (weak).
- Optical and physiological properties of the four cytochromeswere investigated. Lactic dehydrogenase activity was found tobe associated with cytochrome c1554. The two c1-type cytochromes,especially cytochrome c1554, persisted in their reduced formafter the purification through many steps.
- By some combinationsof isolated components reconstruction ofthe oxygen uptake systemcould be realized.
- The oxygen-consuming activity of purifiedoxidase preparationswas accelerated by a-tocopherol but notby Emasoll 4130 andTween 80.
- Some discussions were made onthe nature of terminal oxidase,the role of cytochrome c1552in the electron-transport system,and persistence of reducedstate of c1-type cytochromes.
- A possible scheme of the electron-transferringsystem of Acetobactersuboxydans was presented.
10.
- Several kinds of a-hydroxysulfonates, the bisulfite additioncompounds of aldehydes and ketones, were found to inhibit thephotosynthetic carbon dioxide fixation of the barley and wheatseedlings, tobacco leaf and Chlorella cells. Bisulfite additioncompounds of glyoxal, glyoxylate and benzaldehyde were moreeffective in this respect than those of formaldehyde and acetaldehyde.
- The presence of -hydroxysulfonate causes an increase in ratiosof :14CO2 incorporated in glycolate and alanine, and a decreasein incorporation in serine, malate, isocitrate and citrate.It was inferred that these changes are caused by the blockingof the formation of glyoxylate through inhibition of glycolicacid oxidase by the poison.
- A reaction scheme was proposedto account for the above-statedresults, and the bearing ofthese findings on the possible roleof glycolic acid oxidasein the photosynthetic carbon dioxidefixation and in the formationof amino and organic acids wasdiscussed.
11.
- The formation of phycobilin pigments in a blue-green alga Tolypothrixtenuis was investigated with special reference to the effectsof preillumination with colored lights.
- It was discoveredthat the algal cells are capable of formingphycobilin pigmentsin the dark, if they have been previouslyilluminated for severalhours in the presence of CO2.
- The color of light applied inthe later period of preillumination(chromatic illumination)was found to affect the ratio of phycoerythrinto phycocyaninformed in the subsequent dark period. A greenlight acceleratesthe dark-formation of phycoerythrin, a redlight that of phycocyanin,and the two lights counteractingwith each other in their effects.
- These directive effects of the "chromatic illumination" canbe accomplished within a very short period, for instance, in3 minutes if it is preceded by sufficient "preillumination"with an incandescent or day light fluorescent light. The reactionsoccurring during the period of chromatic illumination does notrequire the presence of CO2 and the aerobic condition.
- Thealga can be grown heterotrophically when supplied with casaminoacids and glucose. Under such a condition the alga forms phycocyanintogether with chlorophyll and carotenoids, but not phycoerythrin.
- On the basis of the results obtained, a tentative scheme forthe biosynthesis of phycobilin pigments in the alga was proposed,assuming the light-induced formation of unknown precursors whichare converted into phycocyanin and phycoerythrin in the subsequentdark period.
12.
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
13.
LIGHT-INDUCED REDUCTION OF NITRATE, NITRITE AND HYDROXYLAMINE IN A BLUE-GREEN ALGA, ANABAENA CYLINDRICA 总被引:1,自引:0,他引:1
- Reduction of nitrate, nitrite and hydroxylamine by intact cellsof Anabaena cylindrica was investigated with special referenceto the stimulating effect of light on these processes.
- Itwas found that in light and under anaerobic condition thesecompounds are reduced to ammonia, with the production of extraoxygen. The stoichiometry of the reactions under these conditionscan be represented as follows: HNO2+H2O=NH2+2O2 HNO2+H2O=NH2+1O2 NH2OH+H2O=NH2+O2+H2O
- Reduction of nitrite and hydroxylaminewas markedly suppressedby CMU in the light but not in the dark.KCN inhibited reductionto the same extent both in the lightand in the dark. Reductionin the light was much less sensitiveto the uncoupling agent,DNP, than was that in the dark.
- Atlow light intensities, CO2 was suppressed by 2030per cent by the simultaneous provision of nitrite, but the nitritereduction was not affected at all by CO2. At high light intensities,reduction of nitrate and nitrite was considerably acceleratedby CO2
- On the basis of these findings, a possible mechanismfor thelight stimulation of the reactions in question was brieflydiscussed.
14.
- As previously demonstrated, normal cells of Chlorella protothecoidesare bleached with degeneration of chloroplasts when they areincubated, under aerobic conditionseither in the lightor in darkness, in a glucose-containing medium withoutadded nitrogen source ("glucose-bleaching"). It was found inthe present study that under the atmosphere of N2, neither bleachingnor growth of algal cells occurs in the dark, while in the lighta significant growth of cells takes place with formation ofa certain amount of chlorophyll.
- Studies on the effects ofvarious inhibitors (ammonium ion,DNP, CMU, -hydroxysulphonates,arsenate, cyanide, azide, andantimycin A) under different conditionsshowed that oxidativephosphorylation is a necessary processfor the occurrence ofthe glucosebleaching as well as the assimilationof glucose(cellular growth). Under light-anaerobic conditionsin the presenceof glucose, assimilation of glucose (cellulargrowth) takesplace being supported by photophosphorylation,but no bleachingoccurs.
- When the algal cells in the courseof bleaching were transferredto the glucose-free mineral medium,the cell growth ceased immediatelybut the cell bleaching proceededfor several hours before itscessation. The respiratory activity,which was high in the glucose-containingmedium, became loweron transferring the algal cells into theglucose-free medium.The lowered level of respiration was maintained,for more than8 hr after the transfer of cells to the glucose-freemedium.
- When the cells in the course of bleaching were placed underthe atmosphere of N2, the cell bleaching ceased almost instantaneously.
- Based on these observations and other inhibition experiments,it was inferred that a certain intermediate(s) produced by theaerobic respiration of glucose is closely associated with theoccurrence of cell bleaching, and that an O2-requiring stepmay be involved in the process of chlorophyll degradation.
15.
- Previous studies have shown that when Chlorella protothecoidesis grown in a medium rich in glucose and poor in nitrogen source(urea), apparently chlorophyll-less cells with profoundly degeneratedplastidsreferred to as "glucose-bleached cellsareproduced either in the light or in darkness. When the glucose-bleachedcells are incubated in a medium enriched with the nitrogen sourcebut without added glucose, an active formation of chlorophylloccurs after a certain lag period under illumination, whilein darkness a very small amount of chlorophyll is formed atabout the same time as in the light. The stimulating effectof light on the chlorophyll formation is not appreciably affectedwhen the photosynthetic CO2-fixation of greening algal cellsis blocked by the addition of CMU. In the present study, itwas further found that the light-enhanced chlorophyll formationproceeds, although at a somewhat lower rate, under aerationof CO2-free air. All the experiments in this work were doneunder these non-photosynthetic conditions to exclude any influenceof photosynthates.
- The effect of light (from daylight fluorescentlamps) on thechlorophyll formation in the glucose-bleachedalgal cells wassaturating at about 1,000 lux. Blue light wasfound to be mosteffective; yellow, green and red light followingin the orderof decreasing effectiveness.
- When the bleachedalgal cells were illuminated for a short periodin the lag phaseof chlorophyll formation and subsequently incubatedin darkness,there occurred an appreciable enhancement of chlorophyllformationin the dark. When the short illumination was appliedat differenttimes of the lag phase, the enhancement was inducedto almostthe same extent. But the longer the duration of theilluminationduring the lag phase, the greater was the enhancementof chlorophyllformation in the subsequent dark incubation.In such experimentsblue light was most effective and red lightleast, as it wasthe case in the experiments of continuous illumination.An intervenientillumination of the bleached cells at lowertemperatures orunder the atmosphere of N2 produced little orno enhancementof the chlorophyll formation in the subsequentdark incubation.
- Based on these results, it was concluded that the light enhancementof chlorophyll formation in the glucose-bleached algal cellsis mediated by a non-chlorophyllous photoreceptor(s), absorbingmaximally blue and yellow light, and that a light-induced changeof the photoreceptor is immediately followed by a certain dark(temperaturedependent and aerobic) process(es) which is connected,directly or indirectly, to the chlorophyll synthesis.
16.
- The photochemical conversion between the precursors of phycocyaninand phycoerythrin in Tolypothrix tenuis was investigated.
- Itwas found that the conversion of phycocyanin-precursor intophycoerythrin-precursor was induced by green light, and thereverse reaction by red light. These reactions proceeded exponentially, indicating that the photochemical process was acceleratedautocatalytically by the reaction-product.
- The rates of thesephotochemical reactions were found to beunaltered by varyingthe incubation temperature (0? to 35?)and the composition ofthe gas atmosphere (presence or absenceof CO2 and of O2 orby an inhibitor of photosynthesis, p-chlorophenyldimethylurea.
- The action spectra of the photochemical interconversions betweenprecursors of phycobilin chromoproteids were found to be distinctlydifferent from the absorption spectra of chlorophyll and carotenoids.The most effective wavelength for inducing the conversion ofphycocyanin- into phycoerythrin-precursor (541 mµ) isnear the absorption maximum of phycoerythrin (565 mµ),and that of the reverse reaction (641 mµ) is near theabsorption maximum of phycocyanin (620 mµ). Additionaldata, indicating that the phycobilin chromoproteids themselvesdo not participate in these processes as light absorber, werealso presented.
- On the basis of these results, a possiblemechanism of the photochemicalinterconversion between the precursorsof phycobilin chromoproteidsis proposed.
17.
- By growing Chlorella protothecoides in a medium rich in glucoseand poor in nitrogen source (urea), entirely chlorophyll-lesscells, called "glucose-bleached cells, were obtained.These cells were found to have neither discernible plastid structuresnor photosynthetic activities. When these cells were incubatedin a nitrogenenriched mineral medium without added glucose,a remarkable formation of fully organized chloroplasts occurredin the light and only partially organized chloroplasts weredeveloped in darkness.
- In the dark-incubated algal cells asmall but appreciable amountof chlorophyll was formed, beingaccompanied by developmentof significant activities for thePMS- and FMN-catalyzed photophosphorylationsand the HILL reaction.The development of the capacity for performingphotosyntheticCO2-fixation, however, was negligible.
- During the processof "re-generation" of chloroplasts in thelight, there occurredactive formation of chlorophyll followedby development of allthe photic activities mentioned above.Chlorophyll formationas well as development of the photic activitiesproceeded firstin a manner of autocatalytic reaction and laterin the formof the first-order reaction. It was inferred thatthe light-absorbingagent which mediates the chlorophyll synthesisis chlorophyllitself.
- The activities for the PMS- and FMN-photophosphorylations,theHILL reaction and photosynthetic CO2-fixation were recognizedalready in the algal cells at an early stage of greening inthe light, in which the "discs" were developed but no completelamellar structure was observed. Further processes of increaseof these photosynthetic and related activitiesas measuredat a high and a lower light intensitieswere studied inrelation to the chlorophyll formation under continuous illuminationand under light-dark conditions. It was found that the PMS-photophosphorylationactivity was developed always in parallel with the chlorophyllformation under these different light conditions. Developmentof the activities for the other photic reactions, however, lagged,to different extents, behind the formation of chlorophyll inthe later phase of greening of algal cells under these conditions.
- Based on these results the modes of formation of the componentsinvolved in these photic reactions were surmised.
18.
ORGANIC ACID SYNTHESIS IN RESPONSE TO EXCESS CATION ABSORPTION IN VACUOLATE AND NON-VACUOLATE SECTIONS OF CORN AND BARLEY ROOTS 总被引:2,自引:0,他引:2
- 14CO2 fixation into organic acids in tips and proximal sectionsof both corn and barley roots was studied as a function of thenature and concentration of the salt in the external solution.
- In comparison with the level of 14CO2 fixation by vacuolateproximal sections in KCI, incorporation was markedly enhancedin K2SO4 and diminished in CaCk. By contrast, non-vacuolateroot tips were indifferent to the type of external salt withrespect to UCO2 incorporation into organic acids.
- The effectof salt type on organic acid formation from 14CO2was most pronouncedat relatively high concentrations.
- The conclusion was reachedthat organic acid synthesis in responsetoexcess cation uptakeis the result of cation movement into thevacuole, and thattransport into the vacuole is mediated bythe low-affinity componentof the dual mechanisms involved inion absorption.
19.
- The effects of 3-(4'-chlorophenyl)-1, 1-dimethylurea (CMU)onthe fluorescence of photosynthetic pigments in vivo wereinvestigatedin blue-green, red and brown algae and in isolatedspinach chloroplasts.CMU caused an increase in steady statelevel of fluorescenceof chlorophyll a, but did not influencethe fluorescence ofphycobilins. The spectrum of the fluorescenceincrement hada peak at 685 m/µ and a shoulder at 730740mµ.These two bands probably arise from chlorophyll a(Cf684) belongingto pigment system II.
- On excitation of chlorophylla in a red alga, Porphyra yezoensis,a fluorescence band witha peak at 720 mµ was observedbesides a shoulder at 685mµ. The 720 m band is inferredto arise from chlorophylla (probably, Cf-1) in pigment systemI.
- On addition of CMUto the algal cells, the induction of fluorescencewas modifiedto take a simple time course. The induction wasobserved onlywith respect to the fluorescence of chlorophylla, but not inthe fluorescence of phycobilins. The spectrumof the "transient"fluorescence showed two emission bands ofchlorophyll a at 685mµ and 740 mµ, and was quitesimilar in form tothe spectrum of the CMU-caused increase insteady state fluorescence.
- These facts were interpreted in terms of the correlation offluorescence of chlorophyll a and the photochemical reactionsof photosynthesis
20.
MODE OF NUCLEAR DIVISION IN SYNCHRONOUS CULTURES OF CHLORELLA: COMPARISON OF VARIOUS METHODS OF SYNCHRONIZATION 总被引:1,自引:0,他引:1
TAMIYA HIROSHI; MORIMURA YUJI; YOKOTA MIZUE; KUNIEDA REIKO 《Plant & cell physiology》1961,2(4):383-403
- Chlorella ellipsoidea was grown synchronously using variouspossible techniques and the mode of nuclear division in eachcase was followed by staining the nuclei according to FEULGEN.
- A satisfactory synchrony in respect to nuclear and cellulardivision was obtained by starting the culture from a homogeneouspopulation of young and small cells and by discontinuing theillumination at the stage which was called the L3-stage. Thestarting young cells were invariably mononuclear and the L3-cellswere either dinuclear or tetranuclear. When the L3 were incubatedin the dark, they ripened further, and after passing througha tetranuclear stage (referred to as the L4) divided into fourmononuclear daughter cells which have been called the Dn-cells.The most clear-cut and repetitive synchronous culture was obtainedwhen the culture (in the light) was started from the Dn-cellsand the illumination was discontinued at the L3-stage untilthe fully ripened cells divided into four each of Dn-cells.
- An apparently "synchronous" culture was also obtained by themethod of programmed light-and-dark regimen, in which a randomculture is subjected to a regular alternation of light and darkperiods of adequate durations. In this case, however, the cellsat different stages of culture showed irregular nuclear patterns,and the average "division number" of mother cells was not constant,being subject to change between 4.0 and 4.9.