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1.
Phosphatases in cucumber roots, whose production was inducedby Ca2$ deficiency, were characterized chromatographically usingATP, 2'(3')-AMP and p-nitrophenyl-phosphate (PNPP) as substrates.Ca2$ deficiency stimulated greater than 10-fold increases inthe activities with these substrates of the non-adsorbed fractionfrom a DEAE-cellulose column. Several fractions associated withthese phosphatase activities were eluted from the column withNaCl solution; their levels increased less with Ca2$ starvation.When the non-adsorbed fraction from Ca2$-straved roots was appliedto a Sephadex G-200 column, fractions associated with 2'(3')-AMPase(phosphatase I) and with both ATPase and PNPPase (phosphataseII) were separated. In the control roots, very weak activitiesof phosphatases I and II were observed at the same positionon the gel filtration. The phosphatase I isolated from boththe control and Ca2$-starved roots was extremely specific tonucleoside 2'(3')-monophosphates, whereas phosphatase II fromboth types of roots had a relatively broad substrate specificity.When phosphatase I from Ca2$-starved roots was stained with2'(3')-AMP in CaCl2 after polyacrylamide gel electrophoresis,a single band was obtained. Phosphatase I from control rootsalso showed a single band, with the same Rf value. PhosphataseII from both types of roots contained two isozyme bands whenthe activities were stained with either ATP or PNPP. These resultsindicate that Ca2$ starvation causes specific increases in thelevel of phosphatases I and II in cucumber roots. (Received October 28, 1981; Accepted January 19, 1982) 相似文献
2.
Proton extrusion from cucumber roots decreased markedly duringCa2+ starvation in the presence of KC1. Vesicles with ATP-dependentproton transport activity were prepared from the microsomalmembrane fraction of control and Ca2+-starved roots. The protontransport rate of the vesicles from Ca2+-starved roots was repressedto less than half of the vesicles prepared from the controlroots. K+-Mg2+-ATPase activity associated with the vesiclesprepared from Ca2+-starved roots was approximately one-thirdof the activity associated with those prepared from controlroots. Km values of the proton transport rate and K+-Mg2+-ATPasefor ATP were much higher in vesicles prepared from Ca2+-starvedroots. The repression of proton extrusion linked with K+ uptake inthe Ca2+-starved roots could be largely caused by the reducedproton pumping activity associated with microsomal membranesin the roots. (Received May 25, 1987; Accepted October 14, 1987) 相似文献
3.
The uptake of K+ by cucumber plants decreased markedly duringCa2+ starvation. A plasma membrane-enriched fraction, judgedfrom the distribution of marker enzymes, was prepared from controland Ca2+-starved roots. The Mg2+- and K+-Mg2+-ATPase activitiesassociated with the plasma membrane-enriched fraction of controlroots were maxima at pH 6.5. Various monovalent cations andpotassium salts of monovalent anions stimulated Mg2+-ATPaseactivity. Vanadate, DES and DCCD inhibited K+- Mg2+-ATPase activity.Of the divalent cations and phosphate esters tested, Mg2+ andATP were most effective for the stimulation of ATPase by K+,whereas Ca2+ was ineffective in replacing Mg2+. Mg2+- and K+-Mg2+-ATPase activities associated with the plasmamembrane enriched fraction of Ca2+-starved roots were much lowerthan those of control roots. Km values of K+-Mg2+-ATPase forATP were comparable for control and Ca2+-starved roots. The K+-stimulated activity of Mg2+-ATPase in Ca2+-starved rootswas approximately one fourth that of the control, whereas therate of stimulation was only slightly lower in Ca2+-starvedroots. (Received May 9, 1984; Accepted September 17, 1984) 相似文献
4.
In apple fruit, active ATP-dependent microsomal Ca2$ uptakeand respiration-dependent mitochondrial Ca2$ uptake were observed. The mitochondrial Ca2$ uptake was depressed by the calmodulinantagonists chlorpromazine hydrochloride (CPZ) and N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamidehydrochloride (W-7). The Ca2$-ATPase from apple mitochondriawas also inhibited by CPZ or W-7. The apparent Km value forCa2$ in mitochondrial Ca2$ uptake (Km=0.35 mM) was similar tothat of mitochondrial Ca2$-ATPase (Km=0.32 mM). The inhibitoryeffect of W-7 on the activity of the mitochondrial Ca2$ uptakewas closely correlated with the inhibition by W-7 of mitochondrialCa2$-ATPase (r=0.996). These findings indicate that the mitochondrialuptake of Ca2$ in apple fruit depends on the calmodulin-mediatedactivation of Ca2$-ATPase. The microsomal Ca2$ uptake was depressed by CPZ, suggestingthat the microsomal Ca2$ uptake may also be modulated by calmodulin.
1 Contribution No. C-72, Fruit Tree Research Station. (Received June 7, 1982; Accepted October 19, 1982) 相似文献
5.
The ATPase activity of the plasma membrane-enriched fractionwas severely inhibited by withdrawal of Ca2+ from the mediumfor 5 days, although the root system appeared to be unaffectedto visual inspection. Partially lipid-depleted ATPases withsimilar ratios of phospholipid to protein were prepared fromthe plasma membrane-enriched fraction of cucumber roots culturedwith control medium and one lacking Ca2+, and their propertieswere compared. SDS disc polyacrylamide gel electrophoresis showedthat the polypeptide components were essentially similar betweencontrol and Ca2+-starved roots. Partially lipid-depleted ATPasereassociated with asolectin, the lecithin from soybean, showedtypical characteristics of plasma membrane type ATPase; pH optimumat 6.5, high specificity for ATP as substrate and strong inhibitionby vanadate but not nitrate. The activity of reassociated ATPaseobtained from the control roots was apparently higher than theactivity obtained from Ca2+-starved roots. The amount of asolectinrequired for maximum activation of the partially lipid-depletedATPase prepared from control roots was much lower than thatprepared from Ca2+-starved roots. Reassociation of partiallylipid-depleted ATPase with asolectin produced higher ATPaseactivity than that with individual phospholipids. The activationof partially lipid-depleted ATPase prepared from control rootswith asolectin was not inhibited by addition of a sample preparedfrom Ca2+-starved roots. Thus, a decrease in the functionalassociation of ATPase with phospholipids might be one of thephysiological injuries in root cell membranes of cucumber causedby Ca2+ starvation.
1Permanent address: Department of Horticulture, College of Agriculture,Chonnam National University, Chonnam 500, Korea. (Received February 23, 1988; Accepted August 18, 1988) 相似文献
6.
The movement of calcium across the elongation zone of gravistimulatedprimary roots of maize (Zea mays L.) was measured using 45Ca2$.Radioactive calcium was applied to one side of the elongationzone about 4 mm back from the root tip and the distributionof radioactivity across the root in the region of applicationwas determined using scintillation spectrometry. The movementof 45Ca2$ across the elongation zone was non-polar in verticallyoriented roots. In gravistimulated roots the movement of labelwas polarized with about twice as much label moving from topto bottom as from bottom to top. A variety of treatments whichinterfere with gravitropism was found to eliminate the polarmovement of 45Ca2$ across the elongation zone. In maize cultivarswhich require light for gravitropic competency, dark grown rootsexhibited neither gravitropism nor polar movement of 45Ca2$across the elongation zone. Upon illumination the roots developedboth gravitropic competency and gravity-induced polar movementof 45Ca2$ across the elongation zone. Similarly, roots of light-grownseedlings lost both gravitropic competency and 45Ca2$ transportpolarity upon transfer to the dark. The results indicate a closecorrelation between calcium movement and gravitropism in primaryroots of maize. (Received July 20, 1985; Accepted September 25, 1985) 相似文献
7.
The Effect of pH on the Binding of Calcium to Pea Epicotyl Cell Walls and its Implications for the Control of Cell Extension 总被引:1,自引:0,他引:1
Cell walls were prepared from the epicotyls of dark-grown pea(Pisum sativum L.) seedlings. The walls were found to bind externally-added45Ca2+, with a binding constant of 4 ? 104 mol dm3and a maximum capacity of 1.5 ? 108 g-ions of Ca2+ perg fresh weight of epicotyl. The binding capacity decreased asthe pH of the medium was decreased below 6.0, suggesting thatthe calcium was bound by an anionic group with an apparent pKof 4.7. More than half the calcium binding was due to polygalacturonicacid in the wall, since up to 60% of the calcium binding capacitywas removed by pre-incubation of the cell walls with polygalacturonase(E.C.3.2.1.15). Only small decreases in calcium binding wereseen following pre-incubation with protease, nucleases, phospholipaseand hemicellulase. These results indicate that calcium willbe displaced from the cell wall at hydrogen ion concentrationswhich are known to occur in the wall during wall extension.They are consistent with a mechanism by which calcium inhibitswall extension by forming ionic bridges between polygalacturonicacid molecules, and also with the hypothesis that calcium andhydrogen ions exert opposing influences on cell wall extensionby competing for the same binding sites on the polygalacturonicacid. Key words: Pea epicotyl, Cell wall, Calcium, pH 相似文献
8.
Salinity Effects on the Activity of Plasma Membrane H+and Ca2+Transporters in Bean Leaf Mesophyll: Masking Role of the Cell Wall 总被引:1,自引:0,他引:1
Net fluxes of H+and Ca2+were measured in the mesophyll tissueof broad bean (Vicia faba L.) leaves and in protoplasts derivedfrom these cells. NaCl at 90 m M enhanced H+extrusion in bothprotoplasts and tissue, but in different ways. Proton extrusionwas inhibited by vanadate, suggesting the involvement of theplasma membrane H+-ATPase in cell responses to salinity. Therewas virtually no effect of NaCl on the net Ca2+flux in protoplasts,while in the tissue a large transient Ca2+efflux followed thesalt treatment. Salt-induced Ca2+efflux was essentially independentof external Ca2+concentrations in the range 0.1 to 10 m M. Also,Ca2+flux responses were saturated above 50 m MNaCl. It is suggested that almost all the measured Ca2+fluxoriginates from Na+/Ca2+and H+/Ca2+ion exchange in the cellwall. This conclusion was supported by the results of modellingcation exchange in the cell wall. Copyright 2000 Annals of BotanyCompany Salinity, membrane transporters, wall ion exchange, proton, calcium, Vicia faba 相似文献
9.
The role of cell wall matrix polysaccharides in gibberellin-regulatedroot growth is unknown. We examined pectic polysaccharides frompea roots treated with or without gibberellin A3 (GA3) in thepresence of ancymidol, an inhibitor of gibberellin biosynthesis.Pectic polymers solubilized by CDTA (trans-l,2-cyclohexanediamine-N,N,N',N'-tetraaceticacid) at 23°C and subjected to gel permeation analysis exhibitedhigh polydispersity with a molecular mass in excess of 500 kDa.Subsequent extraction of cell walls with CDTA at 100°C solubilizedpolymers with an average mol mass of 10 to 40 kDa. Subjectingthe high molecular mass pectic polymers extracted at 23°Cto 70100°C for 2h generated 10 to 40 kDa fragments,similar in size distribution to those solubilized directly fromcell walls by CDTA solutions at 100°C. Pectic polymers from(GA3+Anc)-treated roots were of higher average mol mass thanthose from Anc-treated roots in both the elongation zone andin the basal maturation zone. Since (GA3+Anc)-treated rootselongate more quickly than Anc-treated roots [Tanimoto (1994)Plant Cell Physiol. 35:1019], the slender, GA3-treated rootsmay produce and deposit highly integrated pectins more rapidlythan the thicker, Anc-treated roots in the elongating or elongatedcell walls.
2Present address: Horticultural Sciences Department, POB 110690IFAS, University of Florida, Gainesville, FL 32611-0690 U.S.A. 相似文献
10.
Hayashi Ryuzo; Morikawa Hiromichi; Nakajima Norihiko; Ichikawa Yoshiaki; Senda Mitsugi 《Plant & cell physiology》1980,21(6):999-1005
Polarized infrared absorption spectra of film specimens of theepidermal cell wall of the third internode of pea stems wererecorded before and after treatment with endopolygalacturonase(endo-PG) and endo-pectin lyase (endo-PL). The spectra showedthat the pectic polysaccharides solubilized with endo-PG wereessentially the same as those solubilized with endo-PL. Thedegree of esterification of the pectic polysaccharides was about20%, and their major sugar components were uronic acids (32.8%),arabinose (48.1%) and galactose (19.2%). The polarized infraredspectra showed that pectic polysaccharides have an orientedstructure in cell walls with their molecular chains orientedpreferentially parallel to the direction of cell elongation.
1Present address: Research and Development, Kanzaki Paper Mfg.Co., Ltd., Amagasaki, Hyogo 660, Japan.
2Present address: Wakayama Research Laboratories, Kao Soap Co.,Ltd., Wakayama 640-91, Japan. (Received June 28, 1980; ) 相似文献
11.
Diffusion potentials (concentration and bi- or multi-ionic potentials)in KC1, NaCl, or LiCl solutions have been measured across anisolated cell wall of Nitella, with or without the same concentrationof CaCl2 on either side of the cell wall. The absolute valueof the potentials decreases as the external Ca2+concentrationincreases and it may happen that an inversion of the sign ofthe concentration potentials results when the external Ca2+solution reaches 1 mM. Dosages of K+ and Ca2+ in the cell wallhave shown that Ca2+ easily displaces the monovalent ion fromthe exchange sites and tends to neutralize the cationic exchanger.However, in most cases, the measured potentials are still morenegative than the theoretical potentials which would be setup by a neutral-site membrane in the same conditions. Theseresults suggest that Ca2+ largely reduces the discriminationproperties of the cell wall between cations and anions. 相似文献
12.
The effects of H$ and fusicoccin (FC) on stomatal opening inthe dark were investigated using epidermal strips of Commelinacommunis and Vicia faba cv. Ryosai Issun. Citrate-phosphatebuffer induced maximal opening of stomata at pH 3.0 when testedover the range of 2.7 to 5.0. HCl at 1 mM also induced stomatalopening without appreciable accumulation of K$ in the guardcells. After 4 hr treatment with 10 µM FC, stomata openedwith concomitant accumulation of K$ in the guard cells, although12 hr treatment caused opening without concomitant K$increase. These results suggest that stomatal opening can be caused bysalt accumulation and/or changes of the physicochemical conditionsin the cell wall of the guard cells due to high acidity.
1 Present address: Biological Laboratory, Faculty of Education,Nagasaki University, Nagasski 852, Japan. (Received April 30, 1982; Accepted July 17, 1982) 相似文献
13.
Effect of Phosphorus Deficiency on Phosphatase Activity of Cell Walls from Roots of Subterranean Clover 总被引:6,自引:0,他引:6
DRACUP M. N. H.; BARRETT-LENNARD E. G.; GREENWAY H.; ROBSON A. D. 《Journal of experimental botany》1984,35(4):466-480
Clover (Trifolium subterraneum L. cv. Mt. Barker) was grownin solution culture with adequate (+P) or no phosphate (P).Cell walls were extracted from roots in such a way that theywere uncontaminated by other cellular materials. Phosphataseactivity was assayed using p-nitro-phenylphosphate (NPP). Phosphatasebound to cell walls had a pH optimum between 5.0 and 6.0, irrespectiveof the P supply to the plants. Activity of phosphatase boundto cell walls increased with electrolyte concentration of theassay medium at pH 6.5 but not at pH 5.5. This increase in activitywas probably due to a higher degree of ionization of the cellwall at pH 6.5 than at pH 5.5, and to effects of high ionicstrength in decreasing the mutual repulsion of negatively chargedNPP from negative charges on the cell walls. Cell wall-boundphosphatase did not exhibit Michaelis-Menten kinetics: the concentrationof NPP at which activity was half the maximum rate (S0.5) was0.7 mM for cell walls extracted from roots of both +P and Pplants. Up to 30% of the phosphatase activity bound to cellwalls could be removed using buffer solutions of high pH andhigh ionic strength which contained Triton X100. Both soluble and cell wall-bound phosphatase(s) of roots increasedin activity with P deficiency. The phosphatase activity of cellwalls increased 1.5 fold as the P concentration in the rootsfell from 0.40.2% dry weight. Experiments with sterileroots of clover showed that increases in cell wall-bound phosphataseactivity associated with P deficiency were not due to microbialcontamination. It is argued that phosphatase(s) in cell wallsof roots could make a substantial contribution to the P nutritionof clover in soils deficient in inorganic phosphate by hydrolysingorganic phosphate compounds in the soil. Key words: Phosphatase, Clover, Roots, Phosphorus deficiency, Cell walls 相似文献
14.
Deprivation of Ca2+ from a complete culture medium affectedthe enzyme activities associated with five membrane fractionsof cucmber roots obtained by discontinuous sucrose density gradientcentrifugation. The total activity of K+-ATPase, Cyt. c oxidaseand NADPH-Cyt. c reductase of Ca2+-deficient roots, starvedfor only 4 days, had decreased to 14, 38 and 60% of the activityof the control roots. In general, loss of enzyme activitieswas accompanied by a shift of activity distribution from theheavier density fractions to lighter ones. The amounts of Ca2+ associated with membranes from Ca2+-starvedroots decreased to 5060% of those of the control roots.Both phospholipid and neutral lipid contents in the membranesdecreased markedly while the protein content was not changedby Ca2+ deficiency. Phospholipid analysis indicated a drasticdrop in the percent composition of phosphatidylinositol butan increase of phosphatidic acid. Also, phospholipase D activityincreased remarkably during Ca2+ starvation, paralleling theappearance of Ca2+-deficiency symptoms. Thus, the major effects of Ca2+ deficiency appear to be to stimulatephospholipase D activity and a reduction in membrane bound Ca2+.These effect may be involved in disorganization of the membranestructure and the changes of enzyme activities associated withthe altered membranes.
1Rubber Research Institute of Sri Lanka, Dartonfield, Agalwatta,Sri Lanka. (Received July 15, 1985; Accepted November 21, 1985) 相似文献
15.
Glutamate dehydrogenase (GDH) (EC 1.4.1.3
[EC]
.) purified from greentobacco callus mitochondria was activated markedly by Ca2$ inthe amination reaction. This activation was detectable evenat concentrations below 5 µM Ca2$. Saturation curves for the three substrates of the aminationreaction showed normal Michaelis-Menten kinetics in the presenceof 1 mM of Ca2$, but pronounced substrate inhibition occurredwithout Ca2$. The effect of Ca2$ was chiefly on the maximalvelocity. The saturation curve for NH4Cl in the presence of Ca2$ was modulatedby a change in pH. The apparent Km value for NH4Cl markedlydecreased whereas that for -ketoglutarate increased slightlywhen the pH was raised from 7.3 to 9.0. In contrast, the Kmfor NADH was little affected by raising the pH. The characteristicof GDH which increases its affinity for NH4Cl when the pH israised may be compatible with the detoxification of ammonia.
1 Present address: Mochida Pharmaceutical Co., Ltd. (Received August 24, 1981; Accepted November 28, 1981) 相似文献
16.
Activity of glucose 6-phosphate dehydrogenase (D-glucose 6-phosphate:NADP oxidoreductase, EC 1.1.1.49
[EC]
) preparation from sweet potatoroot tissue was markedly altered in the presence of variousions. Cations or anions were effective in the following order:Na$, K$>Tris$>NH4$>Mg2$>Ca2$, or Cl>NO3,HPO42>SO42>HCO3. Activity was inhibitedat high concentrations of Ca2$, and HCO3,. In an investigationon the dependence of the activity on pH, two activity peakswere clearly observed at low ionic strength. Ionic strength altered both the Km and Vmax for glucose 6-phosphate(G6P). A Lineweaver-Burk plot for the enzyme, with respect toG6P, showed a bimodal nature at low ionic strength; suggestingnegative cooperativity. Deviation from linearity of the plotwas less with an increase in the ionic strength.
1 Present address: Institute of Applied Microbiology, Universityof Tokyo, Bunkyo-ku, Tokyo 113. (Received September 18, 1971; ) 相似文献
17.
A protein kinase which phosphorylates histone was isolated fromthe endoplasmic reticulum-rich fractions of Lemna paucicostata.The enzyme could be solubilized by sonication, and its molecularweight was estimated as 220,000 by Sephacryl S-300 gel filtration.The optimum pH for enzyme activity was 9.09.5 and theactivity was stimulated by Co2$, Mg2$ and Mn2$. Substrate proteinswhich might be phosphorylated by this protein kinase were alsodetected in microsomal fractions of Lemna plants.
1 Present address: Advanced Research Laboratory, HITACHI LTD.,Kokubunji, Tokyo 185, Japan. 相似文献
18.
The carbon metabolism in cell walls of Chlorella ellipsoideawas studied by following 14C incorporation into cell wall constituentsin photosynthesizing, synchronously growing cells. The rateof incorporation was higher at an early growth phase of thecell cycle. The 14C was incorporated into both the major cellwall constituents, hemicellulose and rigid wall,and the radioactivity in the latter was distributed into itstwo components, glucosamine and amino acids. In pulse-chaseexperiments, the 14C fixed photosynthetically in the precedingcell cycle was rapidly transferred into the cell wall constituentsat the early growth phase of the ongoing cell cycle, and thereafterwas gradually released from the cell walls, although the totalamount of 14C in the cells remained constant. It was concludedthat the cell wall constituents are turned over during the growthphase of the algal cell cycle, and that the cell wall metabolismin the ongoing cell cycle is closely connected with the carbonmetabolism in the preceding cell cycle. (Received February 3, 1982; Accepted June 21, 1982) 相似文献
19.
Specific Response of Partially Purified Cell Wall-Bound ATPases to Fungal Suppressor 总被引:1,自引:0,他引:1
Kiba Akinori; Toyoda Kazuhiro; Ichinose Yuki; Yamada Tetsuji; Shiraishi Tomonori 《Plant & cell physiology》1996,37(2):207-214
It was found that NTPases were bound to cell walls of pea andcowpea. The suppressor in pycnospore germination fluid of apea pathogen, Mycosphaerella pinodes, inhibited the ATPase activityin the fraction, which was solubilized from pea cell wall with0.5% Triton X-100, in a dose-dependent manner, but rather enhancedthat from cowpea cell wall even at the concentration of 1 µgml-1. Inhibition by the suppressor of pea cell wall-bound ATPasewas a mixed type of competitive and noncompetitive. Triton X-100PAGE and active staining of ATPase indicated that both TritonX-100 solubilized fractions contained plural molecules thathydrolyze ATP. The Mrs of cell wall-bound ATPases seem to beconsiderably different from those of plasma membranes, and thenumber of cell wall-bound ATPase molecules were different betweenpea and cowpea. The electroeluted fractions corresponding tothe bands of active-stained ATPases were also able to hydrolyzeNTP and PPi. The respective electroeluted ATPases also showedthe species-specific response to the suppressor. These resultsmay confirm our previous concept that putative receptors forthe suppressor might tightly bind to cell wall-bound ATPaseor that the ATPase might be the receptor itself. (Received September 8, 1995; Accepted March 9, 1996) 相似文献
20.
Most nucleases from gametes of Chlamydomonas reinhardtii needCa2$ for full activation. They have been named nuclease C andat least six species of isozymes have been found in the femalegamete (Ogawa and Kuroiwa 1985a). Nuclease C1&2 and C3 were purified from the vegetative cellsof this organism. Nuclease C1&2 exhibited a sharp pH optimumat 9.5, while nuclease C3 preferred a more neutral pH at 7.08.5.Use of the Ca2$-EGTA [ethylene-glycol-bis-(2-aminoethyl ether)-N,N,N',N'-tetraaceticacid] buffer in the reaction mixture made it possible to determinetheir activity at the physiological Ca2$ concentration. NucleaseC3 was not activated at low Ca2$ concentration and exhibiteda sharp optimum at 103{small tilde}104 M. NucleaseC1&2 were activated at a physiological concentration of106 M; increasing the Ca2$ concentration did not affectthe activity. Nuclease C gave active fragments upon trypsin digestion. Trypticfragments of nuclease C1&2 and C3 had molecular weightsof 21,000 (referred as C6T) and 16,000 (C4T), respectively.Upon regulating the digestion, a few fragments were identifiedas intermediates of nuclease C6T by the in situ nuclease assay.These tryptic fragments were similar in molecular size to theminor components of nuclease C found in the cell lysates ofgametes and early zygotes. This finding suggests that a minorspecies of nuclease C may be produced from the major nucleaseC during gametogenesis. (Received June 26, 1985; Accepted August 28, 1985) 相似文献