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1.
L-Leucine Transport in Isolated Protoplasts of Vinca Suspension Culture: Characterization of Uptake 总被引:1,自引:0,他引:1
The uptake of L-leucine into Vinca protoplasts was studied undervarious conditions. The uptake was highly pH-dependent, withthe optimal pH between 3.0 and 4.0. The uptake was also energydependent, since azide, 2,4-dinitrophenol (DNP), carbonyl cyanidem-chlorophenyl hydrazone (CCCP), and iodoacetate inhibited theuptake. Oligomycin, N,N'-dicycIohexyI carbodiimide (DCCD) andvanadate, but not ouabain, inhibited the uptake, suggestingthat ATPase for H+ electrogenic extrusion was necessary to theuptake of L-leucine. The uptake showed stereospecificity, butwas partially inhibited by other L-amino acids. A kinetic studyof the uptake showed that the uptake was multiphasic with threesaturable phases and one unsaturable phase which occurred atconcentrations of L-leucine over 1 mM. The Km values of thethree affinity sites were 1.4 x 103 M, 1.3 x 104M, 4.3 x 105 M; the maximum velocity values were 3.3x 108, 4.5 x 109, 1.8 x 109 mol/10 min/4x 106 cells. (Received April 18, 1981; Accepted August 25, 1981) 相似文献
2.
Selective inhibition of antimycin A-insensitive respiration in Ustilago maydis and Ceratocystis ulmi
Sporidia of Ustilago maydis and conidia of Ceratocystis ulmipossess an antimycin A and azide-tolerant electron transportpathway which apparently diverts electrons to O2 from some pointon the substrate side of the antimycin A block. The alternatepathway (induced by 0.5 µg/ml antimycin A or 5x104M sodium azide) supports a respiratory rate 1.52 timesthat of the normal system, but has a terminal oxidase with alower than normal affinity for O2. A similarly high respiratoryrate in U. maydis is supported by the normal pathway when uncoupledby 4 µg/ml of 4,5-dichloro-2-trifluoromethylbenzimidazole,but a high affinity for O2 in this case indicates that the normalterminal oxidase is utilized. Respiration by the normal pathway in both fungi is only slightlyor moderately inhibited by 1.5x103 M benzohydroxamicacid (BHAM) and 5x104 M 8-hydroxyquinoline. The alternatepathway in U. maydis, however, is inhibited as much as 84 and92% respectively by these two compounds, while alternate respirationin C. ulmi can be inhibited as much as 86 and 76% respectively.BHAM, 8-hydroxyquinoline, 2-pyridinethiol-1-oxide, a,a'-dipyridyl,carboxin, and diphenylamine inhibit alternate respiration ata site on the alternate pathway which is not part of the normalelectron transport system. Antimycin A and azide-insensitiverespiration found in U. maydis and C. ulmi closely resemblesinhibitor insensitivity noted in several fungi and some higherplants. Such an alternate respiratory pathway may be an earlystep in the evolution of oxidative phosphorylation. (Received June 27, 1972; ) 相似文献
3.
Effects of indoleacetic, p-chlorophenoxyisobutyric and 2,4,6-trichlorophenoxyacetic acids on three phases of rooting in Azukia cuttings 总被引:1,自引:0,他引:1
In adventitious root formation of disbudded epicotyl cuttingstaken from light-grown, 5-day-old Azukia angularis seedlings,indoleacetic acid (IAA), 1 x 104 M, applied during thefirst day showed no effect, but enhanced the effect of IAA,1 x 104 M, applied during the second day. Treatment duringthe second day promoted rooting by about 70%, and a combinationof treatments for the first and second days promoted rootingsome 200%. p-Chlorophenoxyisobutyric acid (PCIB), 3 x 104M, and2,4,6-trichlorophenoxyacetic acid (2,4,6-T), 2 x 1044M, applied the first day also enhanced the effect of IAA, 2x 104 M, applied the second day. When applied the second day, PCIB, 2 x 104M, increasedthe number of root primordia or clusters of small cells, butnot die number of protruded roots. Formation of the cell clusterwas inhibited by 2,4,6-T, 3 x 104M, applied the secondday. Rooting processes in Azukia cuttings seem to include at leastthree phases: the first phase is induced not only by IAA butalso by PCIB or 2,4,6-T, the second phase is induced by IAAor PCIB and the diird phase depends specifically on IAA. (Received October 28, 1970; ) 相似文献
4.
Xylopine, an aporphine alkaloid contained in the bark of Xylopiadiscreta strongly inhibits growth of Scenedesmus obliquus; 50%inhibition was caused by 2x105 M of xylopine. Photosynthesis was also strongly inhibited by xylopine at concentrationsabove 104 M. Effects on photosynthesis, however, differeddepending on the ratio of alkaloid concentration to cell concentrationin the reaction mixture, so that under certain experimentalconditions with concentrations of xylopine below 104M, there was some acceleration of photosynthesis. Xylopine strongly inhibited the HILL reaction with benzoquinoneas the HILL oxidant. Respiration was not affected at concentrationscompletely inhibiting photosynthesisd growth of the alga. A probable role of the aporphine alkaloid in controlling lichengrowth in nature is discussed. (Received March 25, 1970; ) 相似文献
5.
5 x 105 M L-phenylalanine overcame the inhibitory effectof white light on cell division in artichoke callus culturesand increased extractable phenylalanine ammonia-lyase (PAL)activity compared to cultures grown in the presence of 5 x 104M phenylalanine The lower concentration of the amino acid alsoenhanced rates of uptake and incorporation of 14C labelled phenylalaninethroughout G1 and S. Differences between the two concentrationswere greatest during S with a 4-fold increase in uptake anda 3-fold increase in incorporation It is suggested thereforethat the capacity of 5 x105 M phenylalanine to offsetthe light effect is due to an indirect stimulatory effect onamino acid and protein metabolism Increased levels of extractablePAL activity would then be reflected by this general stimulationof protein synthesis. Helianthus tuberosus L, Jerusalem artichoke, callus culture, cell division, phenylalanine ammonia-lyase 相似文献
6.
Incorporation of polyamine-spermidine into the nutrient mediumat 106 and 105 M concentrations stimulates pollen-tubegrowth in vitro in Catharanthus roseus L. G. Don. MGBG, an inhibitorof spermidine biosynthesis, at 0.5 x 103 and 1 x 103M concentrations reduced the percentage of germination as wellas tube growth and at a concentration of 1.5 x 103 Mgermination was totally inhibited. Pollen grains incubated inthe medium containing 1.5 x 103 M MGBG, when transferredto a fresh medium with 105 M spermidine, resulted in80% germination recovery, along with considerable tube growth.Experiments with actinomycin-D indicate that stimulation ofpollen-tube growth by spermidine may involve de novo synthesisof protein. Catharanthus roseus, pollen germination, tube growth, spermidine, MGBG, inhibition, actinomycin-D 相似文献
7.
The effects of cyanide on the electron flow in NO3 andNO2 reductions and photosynthetic electron transfer wereinvestigated with intact cells of a photodenitrifier, Rhodobactersphaeroides f. s. denitrificans. In the presence of 30 µMKCN, electron transfer for NO3 reduction was inhibitedby about 70% and the concomitant H translocation was completelyinhibited. However, neither NO2 reduction nor photosyntheticcyclic electron transfer was affected at 30 µM. Theseresults suggested that the electron transfer pathway to NO3has, in addition to a b-type cytochrome and the nitratereductase,a component sensitive to a low concenration of cyanide whichis not involvedin the cytochrome bc1 complex. (Received April 13, 1987; Accepted July 23, 1987) 相似文献
8.
The response of isolated stolons cultured in vitro, to abscisicacid (ABA) has been studied in the presence and absence of kinetin(6-furfurylaminopurine). ABA alone in concentrations from 7.5x 104 mM to 7.5 x 102 mM, inhibited stolon elongationbut failed to promote tuber initiation. In the presence of kinetin,ABA at concentrations of 3.0 x 102 and 7.5 x 102mM markedly inhibited kinetin-induced tuber initiation and stolonelongation, but at 7.5 x 104 and 7.5 x 103 mMABA did not prevent tuber initiation. When stolons were incubated on a medium containing kinetin andlater transferred to one containing ABA with or without kinetin,the inhibitory effect of ABA decreased appreciably as the timeof incubation on kinetin is increased. The results are discussed in relation to the role of ABA inthe inhibition of nucleic acid and protein synthesis and theinteraction with cytokinins and the possible effect of ABA onkinetin uptake, transport and accumulation at the locus of action. (Received February 26, 1969; ) 相似文献
9.
The NADP$-specific isocitrate dehydrogenase was partially purifiedfrom photosynthetically-grown Rhodospirillum rubrum. The pHoptimum is between 7.5 and 9.0 in phosphate buffer. The apparentKm is 3.1x105 M for isocitrate, 5.1x105 M forNADP$, 1.7x105 M for manganese, 1.5x104 M formagnesium, and 3.5x103 M for inorganic orthophosphate.Arsenate exerts a slight inhibition. The Q10 between 17.5°Cand 40°C is 1.62, and the energy of activation at 25°Cis 9.74 Kcal/mole. Glyoxylate and oxalacetate cause concertedinhibition of the enzyme activity. Various nucleotides inhibitthe activity. The kinetics of inhibition by ATP was found tobe mixed type with respect to NADP$ and isocitrate, the Ki valuesbeing 1.17x103 M and 1.10x103 M respectively.The inhibition between ATP and orthophosphate is competitivewith a Ki of 104M. Thiol binding reagents are inhibitory;this inhibition is reversed by cysteine or reduced glutathione. (Received October 1, 1971; ) 相似文献
10.
107 M cycloheximide inhibited bean (Phaseolus vulgaris)root elongation by about 20 per cent but it inhibited absorptionof rubidium, sodium, and phosphate ions to a much greater extent(3471 per cent). Tips of intact plant roots grown inthe inhibitor showed more inhibition in ion uptake than adjacentproximal portions of the same roots and this is taken to indicatethat 107 M cycloheximide does not exert its effect onion uptake by any uncoupling action. Sodium uptake from 0.5 or 10 mM NaCl solutions by root tipswas inhibited by 107 M cycloheximide to twice the extentthat it was in the elongating region of the root. Assuming thatthe inhibitor affects the plasmalemma more than the tonoplast,Epstein's model of parallel operation of system 1 and system2 at the plasmalemma is supported. 相似文献
11.
Five inbred strains (129/J, BALB/cByJ, C3HeB/FeJ, C57BI/6J andDBA/2J) were examined with two-bottle (48 h) preference ratiotesting across concentrations of sodium saccharin (3 x 104M, 103 M, 3 x 103 M and 102 M), d-phenylalanine(103 M, 102 M and 101 M), and l-glutamine(102 M, 3 x 102 M, 101 M and 3 x 101M). Three consistent groupings of strains were observed acrosssubstances and concentrations:
- C57BI/6J (preference at low andhigh concentrations);
- BALB/cByJ and C3HeB/FeJ (preferenceat high concentrations);
- 129/J and DBA/2J (preference at highconcentration for sodiumsaccharin and indifference to d-phenylalanineand l-glutamine).
12.
In azuki bean (Azukia angularis = Vignia angularis) epicotylsections, 5 ? 104 M coumarin inhibited the incorporationof radioactivity from [U14C]glucose into the cellulosefraction by 35% in the absence of indole-3-acetic acid (IAA)and by 40% in the presence of 1 ? 104 M IAA. There wasno inhibitory effect on the incorporation of radioactivity intothe other fractions. Coumarin at 5 ? 104 M reversed thepromoting effect of 1 ? 105 M gibberellin A3 (GA) andthe inhibitory effect of 1 ? 105 M kinetin on IAA-inducedelongation of sections with no significant effects on IAA-inducedelongation. Neither GA nor kinetin had any appreciable effectson cellulose synthesis. No inhibition of cellulose syntheiswas observed with 1 ? 103 M colchichine, which has beenreported to have effects similar to those of coumarin on GA-or kinetin-affected stem elongation. Coumarin at 5 ? 104M was ineffectual in breaking up wall microtubules, while adisrupting effect on wall microtubules was clearly demonstratedwith 3 ? 104M colchicine. From these results, the possible involvement of cellulose synthesisin cell expansion controlled by GA or kinetin was suggested. (Received August 3, 1973; ) 相似文献
13.
Mannitol-1-phosphate dehydrogenase (EC 1.1.1.17
[EC]
) and mannitol-1-phosphatase(EC number yet unassigned) were detected in the brown algae,Spatoglossum pacificum and Dictyota dichotoma. The enzymes wereextracted from algal fronds and their properties were investigatedusing partially purified preparations. Mannitol-1-phosphatase shows maximum activity at pH 7. The enzymehad a narrow substrate specificity. The Km value for mannitol-1-phosphateis 8.3x104 M (30°C, pH 7.0). The enzyme is activatedby Mg++ and Mn++and is strongly inhibited by PCMB, Hg++and NaF. Mannitol-1-phosphate dehydrogenase showed maximum activitiesat pH values 6.5 and 10.2 in reductive and oxidative reactions,respectively. The dehydrogenase also showed narrow substratespecificity; mannitol-1-phosphate and NAD or fructose-6-phosphateand NADH2 are utilized, respectively, in oxidative and reductivereactions by the enzyme. Km values for these substrates andthe coenzymes are 2.5x104 M and 7.1x105 M forthe first pair and 2.8x104 M and 1.3x105 M forthe latter pair. This enzyme was strongly inhibited by PCMBand Hg++, but was only slightly affected by adenosine phosphates. Possible roles of these enzymes in the biosynthesis of mannitolin brown algae are discussed.
1 Contributions from the Shimoda Marine Biological Station ofTokyo Kyoiku University, No. 233. This work was supported inpart by a Grant-in-Aid for Co-operative Research from the Ministryof Education, Japan and in part by a grant to one of us (T.Ikawa) from the Matsunaga Science Foundation.
2 Present address: Chemical and Physical Laboratory, HoechstJapan Research Laboratory, Minamidai, Kawagoe, Japan. (Received February 22, 1972; ) 相似文献
14.
Two groups of tiger salamanders (Ambystoma tigrinum) were conditionedto respond to odorant-air mixtures of n-butyl acetate (8.9 x105M) or n-butyl alcohol (6.7 x l05M). They werethen given tests with various concentrations of the trainingodorants presented using a temporal forced-choice method ofascending limits. Results showed that reliable responses toodorant-air presentations were obtained with concentrationsof n-butyl acetate above 2.4 x l07M and with concentrationsof n-butyl alcohol above 8.5 x 108M. These results arein substantial agreement with previous dectrophysiological findings. 相似文献
15.
In "air-grown" Chroomonas sp. cells, low concentrations of DCMU(less than 0.1 µM) could prevent the inhibition of 14CO2fixation by anaerobiosis under light-saturating conditions (morethan 40 W.m2), with phenazine methosulfate showing asimilar effect. Antimycin A, carbonyl cyanide m-chlorophenylhydrazone(CCCP), and N,N'-dicyclohexylcarbodiimide strongly inhibitedanaerobic photosynthesis at concentrations which did not significantlyinhibit the rate under 2% O2 at high light intensity (200 W.m2),although 0.2 µM CCCP stimulated the rate under 2% O2 tosome extent. On the other hand, KCN inhibited the rate muchmore strongly under 2% O2 than N2, although it inhibited therate very strongly at concentrations above 5 µM both underN2 and 2% O2. These results suggest that the inhibition of photosynthetic14CO2 fixation by anaerobiosis in this alga result from ATPdeficiency caused by over-reduction of electron carriers ofthe cyclic electron flow and that oxygen can prevent the over-reduction.Cyclic electron flow seems to be necessary to provide additionalATP for CO2 reduction under anaerobic conditions, although itseems to be less necessary under aerobic conditions. (Received July 21, 1983; Accepted January 23, 1984) 相似文献
16.
Cytochrome b561 from Rhodopseudomonas sphaeroides had cytochromec (c2) oxidase activity and a pH optimum at 6.0 for this activity.The activity was affected by the ionic strength of the reactionmixture. The apparent Km and maximal velocity (Vmax) valuesin the absence of addea salts were 14 µM and 120 nmoloxidized per min per mg protein for horse heart cytochrome c.Reduced horse heart cytochrome c was reoxidized in first-orderkinetics by this cytochrome b561. The specific activity was0.7 s1 per mg protein at 20°C at the concentrationof 30 µMM cytochrome c. Activity was inhibited by KCN and NaN3, but not by antimycin.The addition of a low concentration of KCN to the cytochromeb561 produced a change in the absorption spectrum, evidencethat KCN interacts with the heme moiety of cytochrome b561.Results of this and preceeding studies show that the cytochromeoxidase (cytochrome "o") described earlier (Sasaki et al. 1970)is cytochrome b561. (Received May 16, 1983; Accepted September 8, 1983) 相似文献
17.
BETZ CHRISTOPH; ULLRICH CORNELIA I.; HARTUNG WOLFRAM 《Journal of experimental botany》1993,44(1):35-39
Electron transport across the plasma membrane of Valerianellalocusta mesophyll cells and intact fronds of Lemna gibba, inducedby 103 M ferricyanide, was inhibited by tetcyclacis,an inhibitor regarded to be specific for cytochrome P-450 mono-oxygenases.The effect was dependent on the concentration of tetcyclacisand the duration of preincubation. The apparent rate of trans-membraneelectron transport increased in the presence of catalase, indicatingtetcyclacis-induced H2O2-production or additional tetcyclacis-independentH2O2 release. The findings suggest an interaction of cytochromeP-450 with the plasma membrane-located electron transport chain.This redox-chain could be involved in the degradation of abscisicacid, being located at the plasma membrane. This assumptionis supported by the finding that ABA inhibits extracellularferricyanide reduction. Key words: Abscisic acid, cytochrome P-450 mono-oxygenase, plasma membrane, tetcyclacis 相似文献
18.
Uptake of uridine by a long-day duckweed, Lemna gibba G3 wasexamined. Km and Vmax for uptake were in the range of 1 to 2x105 M and of 5 to 10 x108 moles/g fresh weight/2hr, respectively. Uptake rate depended on temperature, and theoptimum pH was 5.0. Uridine uptake was competitively inhibitedby some compounds structurally analogous to uridine. However,the activity of uridine kinase was not affected by these compounds,except for cytidine. Uridine uptake was inhibited by metabolicinhibitors, in which uridine taken up was left unconverted toother forms, especially in the presence of DNP. These resultssuggest that uridine was taken up into the duckweed celb bya specific transport system and immediately phosphorylated byuridine kinase. Phosphorylation of uridine was not associatedwith the uridine transport reaction. (Received November 15, 1976; ) 相似文献
19.
The flowers of Skunk-cabbage (Symplocarpus foetidus), like thespadix tissues of other Aroids, have a rapid, carbon monoxideand cyanide (HCN) resistant respiration; oxygen uptake is independentof the oxygen partial pressure over a wide range. Cell fractionswere isolated by differential centrifugation and their oxidativeactivities studied. Oxidation of succinate and citrate by mitochondriacan be inhibited 50 to 60 per cent. by 1 X 103 M. HCN,and antimycin A (AA) causes partial inhibitions. An active mitochondrialcytochrome-c oxidase is present, and it shows a typical sensitivityto cyanide. The mitochondria possess an active reduced diphosphopyridine-nucleotide(DPNH) oxidase system, which is inhibited roughly 80 per cent.by 1 X 103 M. HCN and 1.7 µg./ml. AA. The microsomalDPNH oxidase, which is less sensitive to inhibitors, is lessactive per gramme of tissue than that on the mitochondria. Thefinal supernatant shows little DPNH oxidase. With all fractions,reduced triphosphopyridine nucleotide (TPNH) is oxidized muchmore slowly than DPNH. DPNH-cyto-chrome-c reductase activitywas measured; the mitochondrial system is partially blockedby AA, whereas the microsomal activity is AA-insensitive. Spectro-photometricexamination of a preparation of solubilized mitochondria showedthat cytochromes a, b, and c are present. The results are discussedwith reference to the pathway and localization of hydrogen andelectron transport in the Aroid spadix. 相似文献
20.
Guttation was used as a non-destructive way to study the flowof water and mineral ions from the roots and compared with parallelmeasurements of root exudation. Guttation of the leaves of barley seedlings depends on age andon the culture solution. Best rates of guttation were obtainedwith the primary leaves of 6- to 7-day-old seedlings grown onfull mineral nutrient solution. The growing leaf tissue becomessaturated with K+ below 1.5 mM K+ in the medium, whereas K+concentration in the guttated fluid still increases furtheras K+ concentration in the medium is raised. At 3 mM K+ averagevalues of guttation were 1.42.4 mm3 h1 per plantwith a K+ concentration of 1020 mM; for exuding plantsthe flow was 4.27.6 mm3 h1 per plant and K+ concentration3555 mM. Abscisic acid (ABA) at 106 to 104 M 02h after addition to the root medium increased volume flow ofguttation and exudation and the amount of K+ exported. Threeh after addition of ABA both volume and amount of K+ were reduced.There was an ABA-dependent increase in water permeability (Lp)of exuding roots shortly after ABA addition. Later Lp was decreasedby 35 per cent and salt export by 60 per cent suggesting aneffect of ABA on salt transport to the xylem apart from itseffect on Lp. Benzyladenine (5 x 108 to 105 M)and kinetin (5 x 106 M) progressively reduced volumeflow and K+ export in guttation and exudation and reduced Lp. Guttation showed a qualitatively similar response to phytohormonesas found here and elsewhere using exuding roots. Hordeum vulgare L., barley, guttation, abscisic acid, cytokinins, benzyl adenine, kinetin 相似文献