CHANGES IN EMISSION SPECTRA OF PHOTOSYNTHETIC PIGMENTS IN VIVO

1. 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 730–740mµ.These two bands probably arise from chlorophyll a(C_f684) belongingto pigment system II.
2. 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, C_f-1) in pigment systemI.
3. 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.
4. These facts were interpreted in terms of the correlation offluorescence of chlorophyll a and the photochemical reactionsof photosynthesis

(Received July 20, 1967; )     

A PHENOLIC PIGMENT REACTIVE TO L-LACTATE CYTOCHROME C REDUCTASE OF YEAST

1. A phenolic pigment was extracted from baker's yeast. The pigmentis slowly autooxidizable, and rapidly oxidized with Rhus-laccaseor polyphenol oxidase and reduced by dithionite.
2. The pigmentdissolved in ethylether had an absorption peak at258 mµ,shoulders at 289 and 382 mµ and a plateauat 450–500mµ. The difference spectrum between oxidizedand reducedforms of the pigment showed a wide plateau around500 mµ.
3. The pigment supported the oxygen uptake by reconstructed enzymesystem: L-lactate, L-lactate cytochhrome c reductase and Rhuslaccaseor polyphenol oxidase. In its absence, no oxygen uptake tookplace. The pigment was replaced successfully with p-quinone,catechol and menadione, but not with ubiquinone. The sequenceof hydrogen transport can be represented: L-lactate L-lactatecytochrome c reductase "phenolic pigment" oxidase oxygen.

(Received August 11, 1967; )     

Light-induced changes of b-type cytochromes in the electron transport chain of Euglena chloroplasts

Light-induced changes of b-type cytochromes in Euglena chloroplastswere studied spectrophotometrically.

1. In the dark and at pH 6.5, most of the cytochrome 558 in chloroplastswas in the reduced state, and most of the cytochrome 563, inthe oxidized state. Illumination of chloroplasts at pH 6.5 induceda rapid, but slight oxidation of cytochrome 552 and cytochrome558. The magnitude of photooxidation of cytochrome 558 was greatlyenhanced by the addition of 3-(3',4'-dichlorophenyl)-1,1-dimethylurea(DCMU). The rate of photooxidation in the presence of DCMU wasstimulated by the addition of 0.15 µM Euglena cytochrome552, or 100 µM methyl viologen.
2. Euglena chloroplasts,incubated at 55°C for 5 min showedno significant absorbancechanges for about 10 min after theonset of illumination. However,greater photooxidation of cytochrome558 was observed afterprolonged illumination, or in the presenceof DCMU or ethylenediaminetetraaceticacid (EDTA). Similar resultswere obtained with chloroplastspre-treated at pH 9.0–10.0for 5 min.
3. At pH 9.5, andin the dark, both cytochrome 563 and cytochrome558 were inan almost reduced state. On illumination at thispH, both cytochromeswere photooxidized, with a complicatedkinetics, showing aninitial rapid and small absorbance decrease,followed by a stagnantphase of temporary retarded reaction.In the presence of DCMUor EDTA, photooxidation proceeded rapidlywithout a stagnantphase.
4. At pH 6.5 cytochrome 558, on cessation of illumination,wasquickly reduced to the initial level. At pH 9.5, there wasalsoappreciable re-reduction of cytochrome 558 and 563 whenthelight was turned off at an early stage of illumination.Theamounts of re-reduction of the cytochromes in the subsequentdark period, however, decreased as photooxidation of cytochromesproceeded. This decrease was accelerated by the presence ofDCMU.
5. At pH 9.5 ascorbate and manganese served as electrondonorsfor die DCMU-sensitive photooxidation of cytochromes558 and563.
6. Experimental results are discussed with specialreference tothe occurrence of two pools of electron carriers,one at thereducing side and the other at the oxidizing sideof photosystem2. The role of manganese in the latter pool ofelectron carriersis also discussed.

(Received March 11, 1970; )     

COMPONENTS OF THE ELECTRON-TRANSFERRING SYSTEM IN ACETOBACTER SUBOXYDANS AND RECONSTRUCTION OF THE LACTATE OXIDATION SYSTEM

1. Cytochromes a₁⁵⁹⁰, b⁵⁶⁰, c₁⁵⁵⁴ and c₁⁵⁵² were isolated andpurifiedfrom a strain of Acetobacter suboxydans. The proceduresusedwere described in detail.
2. The main cytochrome band at550-560 mµ in intact cellssplitted at liquid air temperatureinto two bands, 551 mµ(strong) and 559 mµ (weak).
3. 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.
4. By some combinationsof isolated components reconstruction ofthe oxygen uptake systemcould be realized.
5. The oxygen-consuming activity of purifiedoxidase preparationswas accelerated by a-tocopherol but notby Emasoll 4130 andTween 80.
6. 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.
7. A possible scheme of the electron-transferringsystem of Acetobactersuboxydans was presented.

(Received May 16, 1960; )     

PHOTOCHEMICAL INTERCONVERSION BETWEEN PRECURSORS OF PHYCOBILIN CHROMOPROTEIDS IN TOLYPOTHRIX TENUIS

1. The photochemical conversion between the precursors of phycocyaninand phycoerythrin in Tolypothrix tenuis was investigated.
2. 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.
3. 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.
4. 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.
5. On the basis of these results, a possiblemechanism of the photochemicalinterconversion between the precursorsof phycobilin chromoproteidsis proposed.

(Received March 13, 1962; )     

ELECTRON TRANSPORT SYSTEMS OF RHIZOBIUM GROWN IN NODULES AND IN LABORATORY MEDIUM

The electon transport systems of Rhizobium japonicum were studied,comparing cells harvested from effective nodules with thosefrom artificial culture. Participation of the cytochrome systemwas confirmed in both forms of cells. Absorption peaks of thecytochromes of cultured cells were a, b, c type, resemblingthose of Bacillus subtilis, yeast and mammalian tissue. Cytochromea could not be detected in the absorption spectrum of symbioticcells, although the CO binding difference spectrum showed apeak at about 438 mµ, which can be attributed to a componenta₃ or a₁. CO difference spectrum also showed a shoulder at about416 mµ. Cells cultivated under the insufficient supply of oxygen showedthe cytochrome absorption spectrum closely resembled that ofsymbiotic cells. Diaphorase activity was lower in symbioticcells. These results are considered to be due to the insufficientsupply of oxygen within nodule tissue. Succinate oxidation bythe symbiotic cell paniculate was shown to be carbon monooxideresistant. NADH₂ oxidation by the supernatant fraction of symbioticcells was accelerated by flavin mononucleotide, 2, 6-dichiorophenolindophenol, methylene blue and vitamin K₃. ¹Present address: Faculty of Agriculture, Tôhoku University,Sendai. ²Present address: Central Agricultural Experiment Station, Kitamoto.     

AN f-TYPE CYTOCHROME FROM CHLORELLA VULGARIS

A method for isolating an f-type cytochrome (Chlorella cytochrome554) from Chlorella vulgaris var. viridis (CHODAT) utilizingN, N-diethylaminoethylcellulose is described. The spectrum ofreduced Chlorella cyt. 554 has absorption maxima at 554 mµ(-band), 524 mµ (ß-band), 417 mµ (SORETband), 352 mµ, 319 mµ and 277 mµ (proteinband). The oxidized form has absorption maxima at 554mµ530 mµ, (ß-band), 412 mµ (SORET band),360mµ 322 mµ and 275 mµ (protein band). Thespectral characteristics resembled other f-type cytochromes,e. g. in the high SORET to -extinction ratio (6.8) and an asymmetric-absorption band (especially at liquid N₂ temperature) ; butcharacteristic differences were present. Mitochondria from whitelupine seedlings and sweet potato roots reduced Chlorella cyt.554. From the effects of antimycin A and 2-heptyl-4-hydroxyquinolineN-oxide it appears that Chlorella cyt. 554 was reduced sequentiallybefore cytochrome a+a₃ and near the level of the cytochromesof the b type. Oxidation was slow using lupine mitochondriaand nil with sweet potato mitochondria. The oxidation-reductionpotential at pH 7.2 and 30? was 0.35 V. Ascorbate, cysteine,glutathione and Na₂S₂O₄ readily reduced Chlorella cyt. 554.The cytochrome was not autoxidizable and was slowly oxidizedby excess potassium ferricyanide. The reduced form did not reactwith CO and was not adsorbed by IRC-50 or Cellex-P cation exchangers. ¹ Temporary address until September 1961: Department of HorticulturalScience, University of California, Los Angeles 24, California,U. S. A. ² Present address: Plant Industry Station, Pioneering ResearchLaboratory, Marketing Quality Research Division, AgriculturalMarketing Service, Beltsville, Maryland, U. S. A. (Received January 16, 1961; )     

Nature of light-induced absorbance changes at 682 m{micro} and 702 m{micro} in photosynthesis of Anacystis nidulans

Light-induced absorbance changes in the region around the redabsorption band of chlorophyll a were measured in cells andlamella fragments of Anacystis nidulans. In both materials,absorbance decreases were observed at 702 mµ and 682 mµ.(The pigments are designated as P₇₀₀ and P₆₈₀.) The nature ofP₆₈₀ was investigated with special reference to its relationshipto P₇₀₀. In the cells, light absorbed by chlorophyll a causedan absorbance decrease at 682 mµ; Simultaneous illuminationwith light absorbed by phycocyanin caused a partial recoveryof the absorbance decrease. Similar results were observed withthe light-induced absorbance change at 702 mµ. This indicatesthat P₆₈₀ is also an electron carrier in the electron transportchain and occupies a place between the two photoreactions. Inlamella fragments, both the light-induced reversible absorbancechanges of P₆₈₀ and P₇₀₀ appeared in the presence of an electrondonor system; i.e., ascorbate and 2,6-dichlorophenolindophenolor N,N,N',N'-tetramethyl-l,4-phenylenediamine. The experimentsin which the oxidation-reduction potential of the reaction mediumwas changed showed that both P₆₈₀ and P₇₀₀ are one-electroncarriers, having a normal oxidation-reduction potential of 0.44v (assuming that the normal oxidation-reduction potential ofthe ferricyanide-ferrocyanide system is 0.409 v). A possibilitywas suggested that the absorbance change observed at 682 mµis another expression of the oxidation-reduction reaction ofP₇₀₀). (Received October 30, 1968; )     

WATER PERMEABILITY OF THE CELL WALL IN NITELLA

1. A method has been developed to measure the hydraulic conductivityof the wall of the internodal cell of Nitella flexilis.
2. Therate of water penetration through the cell wall varies linearlywith the hydrostatic pressure difference between the two sidesof the wall, showing that water permeability of the cell wallremains independent of the pressure difference applied.
3. Waterpermeability of the cell wall is inversely proportionalto itsthickness It is 30µµmin^–3{dot}atm^–3when the thickness of the wall is 10 µ.
4. Water permeabilityof the cell wall is the same for inward andoutward water flow.The polar water permeability of the entiremembrane system (walland protoplasmic part) of the living celldemonstrated by KAMIYAand TAZAWA (1) is, therefore, due tothe living protoplasmicpart.
5. The ratio of the inward to outward permeability constantsofthe protoplasmic layer alone is higher than that of the entiremembrane system composed of protoplasmic layer and cell wall.

¹ Dedicated to Prof. H. TAMIYA on the occasion of his 60th birthday.The present work was supported in part by a Grant-in-Aid forFundamental Scientific Research from the Ministry of Education. ² Present address: Sh?in Women's College, Kobe. (Received July 21, 1962; )     

Enhancement of Peroxidase-Dependent Oxidation of Sinapyl Alcohol by an Apoplastic Component, 4-Coumaric Acid Ester Isolated from Epicotyls of Vigna angularis L.

A water-soluble component that enhanced the peroxidase-dependent(POX-dependent) oxidation of sinapyl alcohol was isolated fromepicotyls of Vigna angularis. This compound was an ester of4-coumaric acid and a hexose, and it was found in both the apoplastand the symplast. The ester was oxidized by a basic POX isozyme(K_m, about 20 µM) and by an acidic POX isozyme (K_m, about40 µM) that had been partially purified from the apoplasticfraction of epicotyls of V. angularis. These POX isozymes oxidizedsinapyl alcohol at only a very low rate, but a 15-fold enhancementwas observed upon addition of the ester. The concentrationsof the ester required for the half-maximal enhancement weresimilar to the K_m values of the ester for its oxidation by therespective isozymes. The apoplastic concentration of the esterwas higher than 130 µM, suggesting that this ester mightact as a donor of electrons to the apoplastic POX isozymes insitu. Coniferyl alcohol also enhanced the POX-catalyzed oxidationof sinapyl alcohol. The concentrations of coniferyl alcoholrequired for half-maximal enhancement of the oxidation of sinapylalcohol were about 23 and 250 µM when reactions were catalyzedby the basic and acidic POXs, respectively. These values weresimilar to the K_m values of coniferyl alcohol for its oxidationby the respective isozymes. These results suggest that 4-coumaricacid ester and coniferyl alcohol, if it is present in the apoplast,can enhance the POX-dependent oxidation of sinapyl alcohol inthe apoplast of epicotyls of V. angularis. (Received July 1, 1996; Accepted February 5, 1997)     

An action spectrum for photoinduced sporulation in the fungus Trichoderma viride

When a dark grown colony of Trichoderma viride is exposed towhite light for a short time, sporulation occurs only in thenarrow region of mycelia produced just prior to illumination.The action spectrum of this light effect was obtained for wavelengthsbelow 520 mµ using monochromatic irradiation of knownintensity having a band width of 10 mµ. The action spectrumshows 4 distinct peaks at 320, 380, 430 and 480 mµ. Thewavelengths at 320 and 380 mµ are most effective in photoinducedsporulation. The longer wavelengths, 430 and 480 mµ, areconsiderably less effective. The possibility that a carotenoid or a flavin compound may bea photoreceptor in this photoinduced sporulation is discussed. (Received January 4, 1969; )     

ETUDE DES COMPLEXES DE PIGMENTS CHLOROPHYLLIENS D'EUGLENA GRACILIS AU COURS DE LA CROISSANCE ET A L'ETAT ADULTE

Une tude des cellules d'Euglnes et de leurs extraits prparsavec les ultra-sons, chauffs ou non chauffs (quelques heures 35), montre que:

1. le chauffage ne dtruit pas la chlorophylle de faon notable;
2. en prsence d'alcool, un agrgat de chlorophylle ayant unebanded'absorption 740–750 mµ apparait dans lesextraitsd'Euglnes ges de plus de 11 jours;
3. les jeunesEuglnes et les Euglnes ges et chauffes ne peuventformerl'agrgat absorbant aux grandes longueurs d'ondes;
4. deux outrois complexes chlorophylliens diffrents sont impliqusdansla formation des agrgats qui absorbent 740 mµ.

¹ Travail rendu possible par l'attribution d'une bourse d'tudede l'universit de Montral l'un des auteurs (DE K.) et l'octroid'une subvention de recherches (A-1196) du Conseil Nationaldes Recherches du Canada.     

Polyphenoloxidase and the Respiration of Ivy Leaves

1. Polyphenoloxidase is present in ivy leaves but not in thoseof Aucuba or Euonymus.
2. Respiration of intact ivy leaves wasmarkedly stimulated bycatechol (R.Q. approximately=I), gallicacid, caffeic acid,and dihydroxyphenylalanine. The stimulationwas not relatedto injury as far as could be detected and wasnot followed byinhibition. The extra oxygen consumption representsa many timesrepeated oxidation of the amount of catechol supplied.
3. The effect of catechol on the respiration of Aucuba and Euonymusleaves was very small.
4. Cupferron and phenylthiourea, whichinhibit polyphenoloxidasein vitro, nevertheless increased respirationwhen administeredto leaves through the petiole. On the otherhand, when appliedby infiltration, cupferron did cause inhibition,but in Aucubaand Euonymus as much as in ivy.

     

STUDIES ON THE MECHANISM OF GROWTH INHIBITING EFFECT OF LIGHT

1. A substance which inhibits indoleacetic acid (IAA)-and naphthaleneaceticacid (NAA)-induced elongation of Avena coleoptile section andIAA-induced Avena coleoptile curvature was found in an ethersoluble neutral fraction of water extract of sunflower leavesand in agar blocks containing the diffusate from young sunflowerleaves.
2. This substance also inhibits the growth of isolatedsunflowerepicotyl.
3. The R_f value (0.9) of the substance ona paper chromatogramdeveloped with ammoniacal iso-propanolindicates that it isidentical with the inhibitor reported byAUDUS et al. (1956),but not with inhibitor-ß.
4. Theinhibitor can be transported from leaf to stem, and thetransportseems to be accelerated by illuminating the leaf.
5. The auxindiffused from sunflower leaf into agar block may beidenticalwith IAA.
6. A substance, which has the same properties as theinhibitorfrom sunflower leaf, was obtained in crystalline formfrom theleaf of Jerusalem artichoke.
7. The mechanism of growthinhibition caused by this crystallinesubstance seems to involveinactivation of a sulfhydryl group.
8. The reason why the stemgrowth of sunflower seedlings is reducedby strong light isdiscussed: the amount of the inhibitor transportedfrom leafto stem is increased under strong light, and in thestem, growthinhibition is caused by a direct effect of thisinhibitor ongrowth and by its inhibiting effect on the transportof IAAfrom leaf to stem.

¹ Present address: Botanical Garden, Faculty of Science, Universityof Tokyo, Tokyo (Received February 15, 1961; )     

BIOTIN LIBERATION BY THE LICHEN ALGA COCCOMYXA SP. AND BY CHLORELLA PYRENOIDOSA

The unicellular green alga Coccomyxa, a component of the lichenPeltigera aphthosa, liberated about 7.2mµg biotin permg dry weight of cells into the culture medium during a growthperiod of 15–20 days. The corresponding figure for thefree-living alga Chlorella pyrenoidosa was 0.45mµg ofbiotin. Chromatographic analysis indicated that this was freebiotin and not a bound form of the vitamin. The biotin concentrationof rinsed Coccomyxa cells was 1.88mµg per mg dry weightof cells, of which less than 0.01mµg was extractable byhot water. Cells of Chlorella contained 0.16mµg of biotinper mg dry weight, of which 0.11mµg was extractable byhot water. The biotin content of Coccomyxa, which was about12 times that of Chlorella, is thus almost entirely in the boundform. The importance of biotin in the symbiotic interactionsbetween the alga and the fungus in Peltigera is discussed. ¹Present address: University Department of Agriculture, Oxford,England. ²Present address: Institute of Marine Resources, Universityof California, La Jolla, California, U.S.A.     

Photophosphorylation in intact algae: Effects of inhibitors, intensity of light, electron acceptor and donors

The luciferin-luciferase method was used to determine ATP extractedfrom darkmaintained and light-exposed samples of the green algaChlorella pyrenoidosa and of the blue-green alga Anacystis nidulans.A few measurements on Synechococcus lividus (a bluegreen thermophile,clone 65?C) are also reported.

1. The light-minus-dark ATP levels (ATP) from aerobic cells ofChlorella and Anacystis were negative; however, ATP from Synechococcuswas positive. Large positive ATP was obtained in regularly grown(RG: moderate light) Chlorella treated with oligomycin; darklevels were reduced, light levels remained essentially unaffected.In high-light exposed (HLE) Chlorella, oligomycin reduced bothlight and dark ATP levels, but positive ATP was still obtained.However, in Anacystis, which has a different organization ofthylakoid membrane, oligomycin severely reduced both the lightand the dark ATP levels and the ATP remained negative.
2. Theoligomycin (12 µM) treated Chlorella and the untreatedAnacystis and Synechococcus show the presence of cyclic photophosphorylationunder conditions in which the non-cyclic electron flow fromphotosystem II to photosystem I is blocked by 10 µM 3-(3,4-dichlorophenyl)-l,l-dimethylurea(DCMU), or not allowed to operate by the absence of CO₂. Cyclicphotophosphorylation ranged from 10–30% of the maximumATP in RG, to 40–50% in HLE Chlorella. In RG Chlorella,cyclic and non-cyclic (in the absence of DCMU) photophosphorylation(ATP) saturate at about 10³ ergs cm^–2 sec^–1 and10⁴ ergs cm^–2 sec^–1 and 10⁴ ergs cm^–2 sec^–1red (>640 nm) light, respectively; a lag was observed inthe light curve.
3. In Chlorella, the addition of the photosystemI electron acceptormethyl viologen (MV; 1 mM) increased ATPby twofold. Furtheraddition of DCMU (25 µm) reduced thisto the level observedwith DCMU alone. If 1 mM reduced dichlorophenolindophenol orphenazine methosulphate (DCPIPH₂ or PMSH₂, respectively)wasadded along with DCMU, the ATP level was 30–40% ofthecontrol. Further addition of MV increased the JATP to be70–80%of that of the control. These and other resultsconfirm thepresence of both non-cyclic and cyclic photophosphorylationin vivo, the former predominating in Chlorella, and the latterin Anacystis and Synechococcus.

(Received May 1, 1973; )     

CHANGES IN RESTING POTENTIAL AND ION ABSORPTION INDUCED BY LIGHT IN A SINGLE PLANT CELL

1. Effect of light on ion absorption and resting potential of theinternodal cell of Nitella flexilis was investigated under variousconditions.
2. On illumination, the resting potential increasedby about 30mVin 10^–4 M KCl and by about 60 mV in 10^–4M NaClsolution. A similar photoelectric response was also observedin 10^–3 M KCl, 10^–2 M CaCl₂ and 5 x 10^–2 MCaCl₂ solutions, but not at all in 10^–2 M KCl solution.
3. Absorption of ions by the cell took place in parallel withthelight-induced change in resting potential.
4. Red and bluelights were very effective in increasing the restingpotential,while green light was almost ineffective. These differenteffectsof color lights were in good agreement with their effectsinincreasing the osmotic value of the cell.
5. The photoelectricresponse was not affected by phenylurethane,which, on the otherhand, strongly inhibited the light-inducedion absorption.
6. Theuptake of ions by the cell from the external medium intothevacuole is assumed to proceed in two different steps: thefirstis the process involving the ion movements across theoutermostplasmalemma, and the second is that involved in thetransportof ions through the cytoplasmic layer and tonoplast.The formerprocess is considered to be influenced by the increasein restingpotential probably caused by the light absorbed bychlorophyll.The process was, however, suggested to be independentof photosynthesis.On the other hand, the latter process issupposed to be relatedto photosynthesis. A discussion was madealong this line.

(Received July 26, 1962; )     

INTERACTION BETWEEN HELIANGINE AND PYRIMIDINES IN ADVENTITIOUS ROOT FORMATION OF PHASEOLUS CUTTINGS

1. Heliangine at 110^–4 M promoted the adventitious rootformation in hypocotyls of cuttings taken from light-grown (1,900lux) Phaseolus mungo seedlings. The promotion was almost completelyreversed by 310^–4 M uracil, uridine, cytidine, oroticacid or 610^–4 M carbamoyl DL-aspartic acid, and partlyby 310^–4 M thymine or thymidine. Neither 310^–4M cytosine, adenine, adenosine, guanine, guanosine nor a combinationof 310^–4 M carbamoyl phosphate and 310^–4 M L-asparticacid reduced the promotion by heliangine.
2. Uracil did not reducethe inhibiting effect of heliangine onthe indoleacetic acidinduced elongation of etiolated Avenacoleoptile sections.
3. Helianginein an aqueous uracil solution was recovered unchangedafter24-hr incubation at room temperature.
4. The root formation ofPhaseolus cuttings was promoted also by2-thiouracil and 5-fluorouracil.The effect was reversed byorotic acid or carbamoyl asparticacid, but not by carbamoylphosphate plus aspartic acid.
5. Ribonucleaseat 100 µg/ml increased the number of rootsprotruded fromhypocotyls of cuttings by about 260%.
6. A possible interpretationfor the promotion of root formationby heliangine is offered.

¹ Contribution No. 15 from the Botanical Gardens, Faculty ofScience, University of Tokyo, Tokyo, Japan. ² Dedicated to Prof. Dr. H. SODING in commemoration of the 70thbirthday.     

PROMOTION OF ADVENTITIOUS ROOT FORMATION BY HELIANGINE AND ITS REMOVAL BY CYSTEINE

1. Heliangine at 10^–4M promoted the adventitious root formationin hypocotyls of cuttings taken from light-grown (1,900 lux)seedlings of Phaseolus mungo. The promotion was almost completelyreduced by simultaneously supplied 310^–4M cysteine or1.510^–4M cystine, but not suppressed by 310^–4Mof reduced glutathione, alanine or serine.
2. A 4 hr pretreatmentwith 310^–4M cysteine made Phaseoluscuttings less sensitiveto heliangine, but cysteine suppliedafter the treatment withheliangine brought about no effecton the action of heliangine.
3. Cysteine also removed the inhibiting effect of heliangineonthe indoleacetic acid-induced elongation of etiolated Avenacoleoptile sections.
4. In an aqueous solution heliangine formedan addition productwith cysteine, indicating that cysteinecan inactivate helianginewithout any biological processes.
5. On Phaseolus adventitious rooting, no effect was observedofp-chloromercuribenzoic acid, N-ethylmaleimide, 1,4-naphthoquinone,coumarin or penicillin. Reactivity toward sulfhydryl groupsalone does not qualify a substance to be a promotor of rootformation.
6. Maleic hydrazide at 10^–4M promoted root formation,butits effect was not removed by cysteine.

¹ Contribution No. 13 from the Botanical Gardens, Faculty ofScience, University of Tokyo, Koishikawa, Tokyo.     

LIGHT-INDUCED REACTIONS OF UBIQUINONE IN PHOTOSYNTHETIC BACTERIUM, CHROMATIUM D

Light-induced changes in ultraviolet absorption were investigatedin a photosynthetic bacterium, Chromatium strain D. The difference spectra (light-minus-dark) of the changes insteady state level of absorption under various experimentalconditions have common maxima (peaks or troughs) at 275 mµ,315 mµ and 340 mµ; The sign of change, however,varied according to the conditions of illumination (see below).From the shape of the difference spectra and for other reasonsdiscussed in the present paper, the changes at 275 mµwere ascribed to the oxidation-reduction changes of ubiquinone. Illumination under aerobic condition caused a reduction of ubiquinonsamounting to about 6–7 percent of total ubiquinone inthe cell. The addition of Na₂S₂O₃ enhanced the amplitude ofthe photoinduced change to about 25% of the total ubiquinonein the cell. The sign of the photoinduced absorption change at 275 mµwas reverted by the presence of malate or succinate as substrate.On illumination under anaerobic condition, there was a photoinducedoxidation of ubiquinone amounting to about 50% of the total.Under aerobic condition the amount was about 6–7 percentof the total. Transitional changes of ubiquinone in the bacterial cell werealso investigated under various experimental conditions. (Received July 24, 1967; )