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1.
Tonoplast and plasma membrane vesicles were prepared from rice(Oryza sativa L. var. Yuukara) culture cells with step sucrosegradient (30% and 42.9%, w/v) and/or step dextran T-70 gradient(1% and 8%, w/w) to determine the inhibition of tonoplast andplasma membrane AT-Pases by local anesthetics. The degree towhich the anesthetics inhibited these ATPases was of the followingorder: dibucaine>lidocainetetracaine>procaineGABA. Dibucaineranging in concentration from 0.2 nui to 2 mM inhibited tonoplastATPase activity more than plasma membrane ATPase, the half inhibitionsbeing 0.8 and 1.1 mM, respectively. The Km values of tonoplastand plasma membrane ATPases were not affected by dibucaine,but various values were noted for Vmax. Dibucaine inhibitedtonoplast and plasma membrane ATPases solubilized from 0.1%DOC pellet by n-octylglucoside and zwittergent 3–14, respectively.The addition of a phospholipid mixture (asolectin) to solubilizedboth ATPases had no effect on the inhibition by dibucaine. Thus,local anesthetics may act directly on the ATPase moiety withoutlipid mediation. (Received June 15, 1987; Accepted November 13, 1987)  相似文献   

2.
Subunits (, ß, ) and mixtures of subunits ( ß, , ß , ß ) were isolated without denaturationfrom a chloroform extract of chloroplast coupling factor 1 (CF1)from maize (Zea mays var. Ushiku 5-4) and from spinach by fastprotein liquid chromatography (FPLC), on an anion-exchange columnof Mono-Q in the presence of n-octylglucoside (OG) and on achromatofocusing column of Mono-P. The ß -subunitcomplex (CF1 ß ) was the minimum unit required forATPase activity, as was confirmed by the reconstituted complexof ß and subunits. An subunit isolated from maizeinhibited the ATPase activity of CF1 ß from bothmaize and spinach. CF1 ß was found to contain anOG-dependent Mg2+-ATPase. The ATPase activity of CF1 ß required divalent cations, such as Mg2+ or Mn2+, for its expressionin the presence of OG; its optimum pH was 8.0 and it was markedlyinhibited by NaN3. The enzyme hydrolyzed ATP in prefernece toGTP but not CTP, UTP, ADP, AMP or pNPP. Lineweaver-Burk plotsof its activity were curvilinear in the range of 0.6–0.7mM ATP.Mg2+. 1Present address: Department of Biology, School of Education,Waseda University, Shinjuku-ku, Tokyo, 160 Japan. (Received February 15, 1989; Accepted April 20, 1989)  相似文献   

3.
Uptake of the toxic heavy-metal, thallium, was studied in thecyanobacterium Synechococcus R-2 (PCC 7942) using clinicallyavailable 201Tl +. Thallium was found to distribute across theplasmalemma passively, and so the accumulation ratio of theion ([Tl+]i/[Tl+]o) could be used to calculate the apparentmembrane potential (­i,o) of the cells (ETI+i,o = ­i,o).The permeability of the plasmalemma to TI+ (PTI+ 1 to 5 nms–1)is higher than that of K+. Valinomycin does not increase thepermeability of TI+. Transient changes in the ­i,o of cells,because of electrogenic transport of ions, could be detectedfrom its effects upon the uptake rate of TI+. HCO3 hyperpolarizedSynechococcus cells, whereas NH+4, CH3NH+, and K+ led to depolarization.The use of TI+ as a reporter of ­i,o has some inherent limitations.Tl+ is toxic at very low concentrations (inhibitory effectsare apparent after about 6 h at concentrations as low as 1 mmolm–3). The rate of equilibration is slow (t1/25 to 20 min).Equilibration of TI+ takes about 2 h, which limits its valueas a membrane potential probe. Large amounts of TI+ bind tothe surface of the cells making the method impracticable formeasuring accumulation ratios of less than about 10 (­i,o)values smaller than about –60 mV). Cultures continuouslyexposed to Tl+ (10 mmol m–3) eventually become TI+ resistantby actively extruding TI+ (µTI+i,o= –3±0.2kJ mol–1) and so thallium cannot be used as a ­i,oprobe in such cells. (Received October 28, 1997; Accepted August 31, 1998)  相似文献   

4.
In Vigna mungo cotyledons, the -amylase activity increased markedlyduring germination at 27°C in the dark, while the activityof other amylases was very low. The -amylase was purified from4-day-old cotyledons by affinity chromatography on epoxyactivatedSepharose 6B substituted with rß-cyclodextrin andby column chromatography on Bio-Gel P-200. Gel filtration andpolyacrylamide gel electrophoresis showed that the enzyme existsmostly as a monomer (43,000 daltons), but partially aggregatesto form dimer, trimer and further multimers. Ca2+ protectedthe -amylase against heat inactivation. Incubation of the enzymewith 5 mM EDTA or dialysis against 10 mM EDTA resulted in a50–90% loss of activity. The inactivation was partiallyreversed by the addition of Ca2+. Other properties, such asthe amino acid composition, Km value, pH optimum and activationenergy were similar to those of other plant -amylases. (Received May 6, 1981; Accepted June 22, 1981)  相似文献   

5.
Sixteen legumes were grown in N-free media so that N was suppliedentirely by symbiotic N2 fixation. The plant tissues were analyzedfor natural 15N abundance (expressed as 15N per mil relativeto air N2) with a ratio mass spectrometer. The nodules of desmodium,centro, siratro, soybean and winged bean showed high enrichmentin 15N (+9), while red clover showed slight enrichment (+2).The nodules of 9 other forage legumes (Townsville stylo, whiteclover, alsike clover, common vetch, Chinese milk vetch, senna,alfalfa, ladino clover, and hairy vetch) showed little enrichmentin 15N. In all the legumes investigated, particularly in the ureide-transportingplants such as desmodium, centro, siratro, soybean, winged beanand field bean, the 15N value of the shoots was negative (–3.2).The 15N value of the shoots in winged bean and field bean variedby about 1 depending on the Rhizobium strains used. The isotopicmass balance of 13 legumes indicated that isotopic fractionationoccurs during N2 fixation by the legume-rhizobia symbiosis witha preference for 14N over 15N, resulting in a 15N value of –0.2to –2 in the whole plant. The results indicate that 15N/14N isotopic discrimination witha preference for the lighter atom may occur in both N2 fixationand export of fixed N from nodules. 1Present address: Department of Soils and Fertilizers, NationalAgriculture Research Center, Kannondai, Tsukuba, Ibaraki 305,Japan. (Received October 8, 1985; Accepted April 7, 1986)  相似文献   

6.
A Ras-related NTP-binding protein was partially purified froma membrane fraction derived from the mycelia of Neurospora crassa.[-32P]ATP and [-32P]GTP were incubated with mem brane and solublefractions which were then irradiated with UV light to inducecrosslinking of tightly bound nucleotides. After SDS-polyacrylamidegel electrophoresis, blotting onto a nitrocellulose filter andautoradiography it was apparent that most of the proteins thatbound [-32P]-GTP also bound [-32P]ATP. Pretreatment of the membranefraction with Ras-specific antibody effectively blocked thebinding of [-32P]ATP and [-32P]GTP to several ATP-GTP-bindingproteins. The band of a protein with a molecular weight of 26kDa on the SDS-polyacrylamide gel cross-reacted strongly withthe Ras-specific antibody. The protein was extracted from thegel and further purified by repeated gel electrophoresis. Thepurified protein bound [-32P]ATP, [-32P]-GTP, [-32P]CTP and[-32P]UTP at 1.6x10 M and was autophosphorylated in thepresence of [-32P]ATP and [-32P]GTP at 1.7x10 M. Pretreatmentof the protein with Ras-specific antibody partially blockedthe autophosphorylation in the presence of these nucleotides.The binding of [-32P]ATP to the NTP-binding protein was blockedby addition of ATP at 10–4–10–3 M. ATP ata concentration of 10–4 M prevented the binding of [-32P]to a greater extent than did GTP at the same concentration.Binding of [-32P]CTP and [-32P]UTP to the protein was also observed. (Received October 7, 1991; Accepted July 14, 1992)  相似文献   

7.
Various Cucurbita seed globulins showed patterns similar toone another on SDS-gel electrophoresis, and ß bandsfor unreduced globulins and , ', and ' bands for reduced ones.On gel electrophoresis in 6 M urea, reduced globulin gave twoacidic and two basic bands. These corresponded to and ' chainsand 1 and 2 chains, respectively, identified by two-dimensionalurea-SDS gel electrophoresis. The compositions of the and ßsubunits were proposed. (Received September 8, 1977; )  相似文献   

8.
Oryzains, cysteine proteinases of rice seeds, are induced byGA3 in germinating rice seeds [Abe et al. (1987) Agric. Biol.Chem. 51: 1509]. The effects of GA1, GA3, GA4, GA9, and GA20on the production of oryzain and -amylase were investigatedin embryoless half- and whole-seeds of rice (cv. Nipponbare).When gibberellins (GAs) were incubated with embryoless half-seeds,GA1, GA3 and GA4 induced oryzain and -amylase, but GA9, andGA20 did not. GA9 and GAM induced oryzain and -amylase productionin whole seeds, but this production was inhibited by the simultaneousapplication of prohexadione, an inhibitor of 2ß- and3ß-hydroxylation of GAs. Prohexadione did not inhibitthe activities of oryzain and -amylase induced by GA1. Theseresults suggest that GAs possessing the 3ß-hydroxylgroup induce activities of oryzain and -amylase in rice seedsand that GA9 and GA20 have activity only after they are convertedmetabolically to active GAs, probably GA4 and GA1, respectively.GA1, was more active than GA4 in both half seeds and wholeseeds incubation. Oryzain and -amylase activities induced byGA4 were significantly inhibited in the presence of 10–4M prohexadione. This suggests that the conversion of GA1, toGA4 (13-hydroxylation) might be inhibited at a high dose ofprohexadione in whole seeds. 4Present address: Institute of Food Development, Kyung Hee University,Suwon 449-701, Korea  相似文献   

9.
Two proteolytic activities I and II involved in the globulindegradation were detected in pumpkin seeds. Activity I, hydrolyzing and ß subunits of the globulin to form Fß,was found in both dry seeds and cycloheximide-treated cotyledons,and decreased during germination. Activity II, hydrolyzing Fßto produce small peptides and amino acids, was not observedin dry seeds but found in cycloheximide-treated cotyledons,increased up to 4 days, and gradually decreased during germination. Activity I gave limited hydrolytic products from the globulinand the chain, but not from Fß, the chain and some animal proteins. It was inhibitedby EDTA. On the other hand, activity II hydrolyzed Fßand the chain faster than the globulin, the chain and some animal proteins. It was inhibitedby EDTA and p-chloromer-curibenzoate, and activated by ß-mercaptoethanol,dithiothreitol and CoCl2. Optimum pH's were at about 6.8 andat 6.0 to 6.8 for activities I and II, respectively. The degradation process of the globulin can be divided intotwo steps: the first step is the conversion of globulin to Fßand the second step, Fß to small peptides and aminoacids. (Received November 9, 1979; )  相似文献   

10.
Effects of l, N6-ethenoadenylates (e-adenylates) were testedon phosphorylation, and electron transport under phosphorylation,arsenylation and quasi-arsenylation (stimulation of electrontransport in the presence of ATP, AMP and arsenate) conditionsin isolated spinach chloroplasts. -ATP as well as ATP partially inhibited ferricyanide reductionthrough binding to the chloroplast coupling factor 1 with anapparent dissociation constant (KDapp) of around 5µM,which was remarkably larger than that for ATP (ca. 2µM).e-ATP at below 500 µM had no effect on phosphorylationbut inhibited quasi-arsenylation in competition with ATP withan apparent inhibition constant (K1app) of around 60 µM. -ADP as well as ADP partially inhibited ferricyanide reductionwith a KDapp value close to that for -ATP. -ADP was phosphorylated(the apparent Michaelis constant, Kmapp=80µM) accompanyingstimulation of ferricyanide reduction to the magnitude predicted(P/e=l). -ADP-arsenylation was also detected by stimulationof ferricyanide reduction. -AMP alone caused little inhibition of ferricyanide reductionas AMP, but competitively depressed the electron transport inhibitionby ADP and ATP with a K1app value of around 200 µM. -AMPwas not effective for ADP phosphorylation but inhibited stimulationdue to quasi-arsenylation coupling in competition with AMP K1app=150µM Among the possible combinations of adenylates and -adenylatesfor quasiarsenylation, only [ATP+AMP] could couple with theenergy transduction mechanism. Based on the specificity of binding sites to adenylates and-adenylates, an attempt was made to distinguish at least four(two pairs) kinds of binding sites (at least six sites in toto)on the chloroplast coupling factor 1 for photosynthetic energytransduction. When one pair of sites is occupied by the designatedadenylates or -adenylates (allosteric effectors), the couplingfactor is thought to be in a conformation for coupling withthe energy transduction mechanism in the presence of phosphateor arsenate. 1Presented to the 1st Symposium of Japan Bioenergetics Group,December 19, 1975, Osaka. (Received February 17, 1976; )  相似文献   

11.
A rapid and sensitive method to determine the relative specificity() of ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO)using anion-exchange chromatography is described. We employedthe open gas system for the reaction of RuBisCO to get the mostreliable CO2 and O2 concentrations in the reaction mixture.3-Phosphoglycerate and 2-phosphoglycolate which were formedin the RuBisCO reaction were completely separated and directlymeasured with anion-exchange chromatography without using radioisotopes.The determination of the value was accomplished in 3 h. The values of RuBisCO enzymes from higher land plants were between90 and 96, and those from bacteria including cyanobacteriumwere close to 45. These values were in agreement with previouslyreported values. The enzyme of the red macroalga Porphyra yezoensisexhibited a value of over 140, as expected from the reportedvalue of the enzyme from the red microalga Porphyridium cruenteum.RuBisCO from the green macroalga Ulva pertusa had a value closeto 70 and similar to that of the enzyme from the green microalgaChlamydomonas reinhardtii. 4On leave from Research and Development Center, Unitika Ltd.,23 Kozakura, Uji, Kyoto, 611 Japan. 5Present address: Nara Institute of Science and Technology,8916-5 Takayama-Cho, Ikoma, Nara, 630-01 Japan  相似文献   

12.
-Carotene was isolated from previously known sources and itsspectral and adsorption properties compared with those of asimilar carotene recently observed in Cryptomonas ovata. Identitywas established. Similar comparisons with synthetic 1-carotenepoint to the identity of the natural and synthetic compoundsand permit assignment of KARRER and EUGSTER's formulation for1-carotene to the naturally occurring representative. 1 Dedicated to Prof. H. TAMIYA on the occasion ot his 60th birthday. 2Contribution from the Scripps Institution of Oceanography,University of California, San Diego. (Received January 22, 1963; )  相似文献   

13.
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; )  相似文献   

14.
An -glucan was isolated from 11-day-old suspension-culturedrice cells by extraction with hot Na-phosphate buffer (pH 6.8).The -glucan had []D=+234? (C = 0.14, in water) and its averagemolecular weight was estimated to be about 1.4 ? 104, basedon elution characteristics on acalibrated Sepharose CL-6B column.Upon partial acid hydrolysis, the -glucan gave mainly malto-oligosaccharides.The maximum absorption of the iodine complex of the -glucanin the presence of Na2SO4 was at 470 nm. The results of hydrolysisby , ß- and iso-amylases and methylation analysisindicated that the isolated -glucan is a highly branched polysaccharidewith an average chain length of 9. The exterior and interiorchain lengths of the -glucan were calculated to be 5 and 3,respectively. (Received July 23, 1986; Accepted February 7, 1987)  相似文献   

15.
Pumpkin seed globulin is composed of heterogeneous polypeptidechains, acidic and chains and basic 1 and 2 chains (12). This study showed that the basicchains had similar N-terminal sequences, Gly-Leu-Asp-Glu-Thr-Ile-for the 1 chain and Gly-Leu-Glu-Glu-Thr-Ile- for 2. On the contrary,the N-terminal sequences of the acidic and chains were dissimilar, Ile-Gln-Gly-Tyr- for the chain and no N-terminal residue for the chain, according to routine terminal analysis. Pyrrolidonylpeptidase digestion of the chain and its thermolysin digestion followed by Edman degradationsrevealed that the N-terminal sequence of the chain was < Glu-Ile-Glu-Gln-Gln-Glu-Pro(Trp,Ser)-. The N-terminal sequences and the C-terminal residuesindicated that the acidic and chains were more heterogeneous than the basic 1 and 2 chains.A preliminary study on the degradation of storage globulin isalso presented. (Received November 9, 1979; )  相似文献   

16.
Nucleoside triphosphate(NTP)-binding proteins were detectedin the crude extract of mycelia of Neurospora crassa, whichwas treated with 1% Lubrol PX and fractionated by gel filtration.Protein fractions showing the capacity to bind [35S]ATPS or[35S]GTPS were designated as AGN1 to 6. The binding of [35S]ATPSor [35S]GTPS was prevented in the presence of 0.1 mM ATP orGTP except that in fractions AGN1 and 2, the presence of GTPstimulated the binding of [35S] ATPS to ATP(NTP)-binding proteins.ATP or GTP was 1 to 2 orders of magnitude more effective thanCTP or UTP in preventing the binding of [35S]GTPS in AGN1, 2and 5. Among these fractions AGN1, 2, 5 and 6 showed activityto hydrolyze 1 nM [–32P]ATP or [–32P]GTP. NTP-bindingproteins bound with [35S]ATPS or [35S]GTPS had lower apparentmolecular weights than the same proteins without bound nucleotide.Proteins bound with [35S]ATPS or [35S]GTPS and those [32P]ADP-ribosylatedby endogenous ADP-ribosyl transferase in each fraction wereanalyzed by SDS-PAGE. About 20 species of ATP or ATP-GTP-bindingproteins were detected, several of which were ADP-ribosylated.The binding of [35S]ATPS or [35S]GTPS to NTP-binding proteinswas confirmed by the comparison of non-boiled and boiled samplesimmediately before loading to SDS-PAGE. ATP, GTP, CTP or UTPat the concentration of 0.1 mM effectively removed [33S]ATPSor [35S]GTPS bound to NTP-binding proteins. (Received December 10, 1990; Accepted April 18, 1991)  相似文献   

17.
The sexual agglutinability of haploid cells of heterothallicSaccharomyces cerevisiae was repressed when they were culturedin the absence of easily fermentable sugars, such as glucoseand mannose. The repression was reversed by the action of hormone-likesubstances of the opposite mating types. The substance producedby mating type cells was identical to subtsance-I which isknown to induce sexual agglutinability of inducible matingtype cells. The mating type cells produce a new hormone-likesubstance which induces or enhances sexual agglutinability of mating type cells. A crude fraction of the mating type-specific substance ( substance-I)was obtained by passing the culture filtrate of mating typecells through Amberlite CG-50 (H+ form), followed by elutionwith 1.5 M ammonia. 2 On leave from Osaka City University. (Received December 25, 1975; )  相似文献   

18.
The effects of -hydroxy-2-pyridinemethanesulphonic acid (-HPMS)upon net photosynthesis (Pn, the CO2 compensation point (),post-lower illumination burst of CO2 (PLIB) and post-lower temperatureburst of CO2 (PLTB) in detached rye (Secale cereale L.) leaveswere investigated. At low concentrations ( 0.5 mol m–3),-HPMS initially stimulated Pn and decreased the magnitude ofboth PLIB and PLTB. The decreased at all concentrations of-HPMS (0.05–5.0 mol m–3. The effects of -HPMS onPn and were time-dependent and, after a few minutes, the Pnwas inhibited while values increased considerably. At a higherconcentration (5.0 mol m –3), the transient effects of-HPMS were shorter () or not observed at all (Pn. Both PLIBand PLTB, when expressed in relation to Pn, increased at higherlevels of this compound. Similar data with respect to the effectsof -HPMS on PLIB and PLTB were found for leaves of dandelion(Taraxacum officinale L.). The results suggest that -HPMS may stimulate Pn by inhibitingphotorespiration, as originally suggested by Zelitch (1966),but only at low concentrations and over a short time span. Thedecrease of PLIB and PLTB values at low -HPMS levels is consistentwith these processes being a residual activity of the glycolatepathway. Key words: CO2 compensation point, -hydroxy-2-pyridinemethanesulphonic acid, photorespiration, photosynthesis  相似文献   

19.
Effects of -hydroxy-2-pyridinemethanesulfonate (-HPMS), 2,3-epoxypropionate(glycidate), and cyanide on the photosynthetic activities ofChromatiumwere studied. -HPMS stimulated photosynthetic CO2fixation in the bacterial cells in both N2 and O2 environments.The formation and subsequent excretion of both glycolate andglycine in the O2 atmosphere were markedly enhanced by -HPMS.In contrast to a recent report by Zelitch [Arch. Biochem. Biophys.163: 367–377 (1974) ] that glycidate specifically inhibitsglycolate formation in tobacco leaf disks, we found that ithad no influence on CO2 fixation by Chromatium in either N2or O2 atmosphere, and that the synthesis and extracellular excretionof glycolate were markedly stimulated by glycidate treatment.Cyanide (0.01–1 mM) exerted a marked inhibitory effecton photosynthetic CO2 fixation in N2. In O2 atmosphere, photosynthesiswas stimulated by 0.01 mM cyanide, and inhibited by it abovethis level. Both the incorporation of 14CO2 into glycolate andthe total synthesis of glycolate in the light were also enhancedby 0.01 mM cyanide, and strongly inhibited above that concentration. 1This is paper XXXVI in the series "Structure and Function ofChloroplast Proteins," and the research supported in part bygrants from the Ministry of Education of Japan (No. 111912),the Toray Science Foundation (Tokyo) and the Naito Science Foundation(Tokyo). (Received May 31, 1976; )  相似文献   

20.
Auxin-induced changes in the mechanical properties of cell wallwere examined by both positive and negative pressure jump methodsusing hypocotyl segments excised from the 3-day-old seedlingsof cowpea that has been treated with uniconazole, a potent inhibitorof the biosynthesis of gibberellins. In such segments (U-segments)that were deficient in endogenous gibberellin, auxin increasedonly the effective turgor (Pi–Y) and did not change theextensibility () of cell wall. As a result, the extent of theauxin-induced promotion of growth was halved. However, auxinwas able to increase of U-segments that has been pretreatedfor two hours with GA3 prior to the application of IAA. Measurementof intracellular pressure (Pi) with a pressure probe revealedthat auxin did not change Pi in either U-segments or GA3-pretreatedsegments. The results suggest that auxin can decrease the yieldthreshold of the cell wall (Y) independently of gibberellinbut can increase only in the presence of gibberellin. The differencebetween and Y in terms of their requirement for gibberellinto respond to auxin suggests that they are mutually separablemechanical properties that originate from different molecularprocesses that occur in the architecture of yielding cell walls. 3Present address: Ohishi, Enden, Mori-machi, Shuchi-gun, Shizuoka,437-02 Japan  相似文献   

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