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1.
The mechanism of the regulation of the activation of ribulose1,5-bisphosphate carboxylase/ oxygenase (RuBisCO) by inorganicphosphate (Pi) in the presence of limiting concentrations ofCO2 was explored. The activation state of RuBisCO increasedsigmoidally following a biphasic kinetics against the concentrationof Pi in the activation mixture with an intermediary plateauat 2 to 3 mM Pi when the enzyme was activated for 30 min. Theintermediary plateau could not be seen when the preincubationtime was 10 min and the activation was completed at 10 mM Pi.RuBisCO from Euglena also showed a quite similar activationkinetics. The activation was not due to the contaminating CO2included in the stock Pi solution or in the activation buffercontaining the enzyme. The experiments with 2-carboxyarabinitol1,5-bisphosphate showed that the Pi stimulated activation wasdue to the promotion of binding of the activator CO2 to theactivation sites. It was also found that Pi increased the affinityof RuBisCO for the activator CO2 5.4-fold accompanied by a decreaseof the half-saturating concentration of CO2 to 1.6 µMat 20 mM MgCl2. Physiological significance of the effects ofPi on the activation of RuBisCO is discussed. 2Present address: Laboratory of Plant Molecular Physiology,Research Institute of Innovative Technology for the Earth (RITE),9-2 Kizugawadai, Kizu-cho, Soraku-gun, Kyoto, Japan.  相似文献   

2.
The development of therapeutic glycoprotein production usingthe baculovirus expression system depends on the ability ofinsect cell lines to reproduce site specific mammalian-likeN-glycans. A combination of 1H-NMR and mass spectrometry techniques(MALD-MS, ES-MS, and CID-MS-MS) allowed us to elucidate theN-linked oligosaccharides microheterogeneity on three differentN-glycosylation sites, Asn233, Asn476, and Asn545, of a baculovirus-expressedrecombinant bovine lactoferrin produced in Mamestra brassicae.Two families of N-glycan structures have been found: first,oligomannosidic glycans (Man95GlcNAC2) and secondly, short truncatedpartially fucosylated glycans (Man3–2[Fuc0–1]GlcNAc2).These results indicate that Mamestra brassicae cell line isnot able to synthesize complex N-glycans, even if an  相似文献   

3.
The ability of phytochrome from etiolated pea shoots (Pisumsativum L. cv. Alaska) to bind to various chromatographic adsorbentsand its mobility during non-denaturing electrophoresis wereexamined with phytochrome in either the red light-absorbingform (PR) or the far-red light-absorbing form (PFR). Preferentialbinding of PFR to modified hydrophilic polyvinyl resins, suchas butyl Toyopearl, phenyl Toyopearl, Blue Toyopearl (CibacronBlue F3G-A conjugated) and Red Toyopearl (Procion Red HE-3Bconjugated), was observed. A simplified method for purificationof native phytochrome was developed based on the propertiesof PR and PFR. PFR bound preferentially to the hydrophobic adsorbents,to indicate that the surface of PFR is more hydrophobic thanthat of PR. A difference in net surface charges between PR andPFR was detected by an analysis based on the different mobilitiesof the two forms during non-denaturing polyacrylamide gel electrophoresisin gels prepared with various concentrations of polyacrylamide.The apparent molecular weights of PR and PFR, estimated fromthe analysis, were 378 and 419 kilodaltons, respectively. Thedifference suggests that a significant change in molecular shapeoccurs during the photoconversion. The differences in surfaceproperties of PR and PFR are discussed. (Received April 20, 1991; Accepted August 26, 1991)  相似文献   

4.
An attempt was made to examine the possible connection betweenself-incompatibility in Lilium longiflorum and the stress responseusing pistils after self-incompatible pollination. The growthof pollen tubes in the pistil after self-incompatible pollinationwas promoted by treatment with germanium compounds [(GeCH2CH2COOH)2O3and GeO2], which are scavengers of active oxygen species, suchas O2 and H2O2. The promotion by germanium compoundsof the growth of pollen tubes after self-incompatible pollinationwas reflected by the detection of elevated levels of activityof superoxide-forming NADPH-dependent oxidase, xanthine oxidase,superoxide dismutase, catalase and ascorbate peroxidase, allof which are associated with stress responses, in pistils uponself-incompatible pollination as compared to the activitiesof these enzymes after cross-compatible pollination. A possibleconnection between self-incompatibility and stress in pistilsupon self-incompatible pollination is discussed on the basisof these results. (Received October 9, 1995; Accepted November 11, 1996)  相似文献   

5.
Azide ions inhibited O2 evolution in PSII membranes from spinachin a time-dependent manner in the light until all activity disappeared.Illumination in the presence of azide (azide-phototreatment)irreversibly inhibited the following processes: (1) both theoxidation of water and the electron transport between the redox-activetyrosine 161 of the D1 protein (YZ) and the secondary quinoneelectron acceptor (QB) site, to the same extent; (2) the donationof electrons to the primary quinone electron acceptor (QA),as measured by monitoring the maximum variable fluorescenceof Chl; and (3) the photoproduction of the YZ radical (Y). Thus,the primary site of inhibition appeared to lie between YZ andQA. On illumination of Tris-treated PSII membranes in the presenceof azide, production of the azidyl radical was observed by spin-trappingESR. Yield of Y in Tris-treated membranes on illumination wassuppressed by azide. Electron transport from YZ to QB in Tris-treatedmembranes was inhibited only when the azidyl radical was photoproduced,and it was inhibited more rapidly than it was in the oxygenicPSII membranes. These results indicate that the azidyl radicalwas produced via a univalent oxidation of azide by Y and thatit irreversibly inhibited the electron transport from YZ toQA in Tris-treated membranes. Although the azidyl radical wasundetectable in the oxygenic PSII membranes, probably due tosteric interference by the peripheral proteins of water-oxidizingcomplex with the access of the spin-trapping reagent to theproduction site of the radical, the participation of the azidylradical in the inhibition of the oxygenic PSII membranes issuggested since simultaneous occurrence of both electron transportand azide was required for the inhibition. Possible inhibitorymechanisms and the target sites of azidyl radical are discussed. (Received April 21, 1995; Accepted July 3, 1995)  相似文献   

6.
The responsiveness of non-dormant, upper cocklebur (Xanthiumpennsylvanicum Wallr.) seeds to various germination stimulants,such as CO2 C2H4 CS(NH2)2, BA and enriched O2, decreased withincreasing periods of water imbibition and was completely lostin the state of secondary dormancy. Unlike CO2 BA and CS(NH2)2however, C2H2 and enriched O2 effectively prevented the developmentof secondary dormancy, and their combination was the most effectivefor stimulating the germination of seeds which had undergoneimbibition for a long time. CS(NH2)2 and BA were effective,not by themselves but either under anaerobiosis or elevatedO2 tension. Growth of the axial and cotyledonary segments excisedfrom aged seeds remained responsive to these germination stimulantsand could be further stimulated by exogenous C2H2. With imbibitionat a lower temperature, the seeds maintained high germinationin response to various stimulants and a high rate of C2H2 andCO2 production during a long period of water imbibition. Theseresults are discussed in terms of the two possible causes forthe loss of responsiveness or induction of the secondary dormancy. (Received June 27, 1978; )  相似文献   

7.
The rate of total dry matter production of a vegetative crop,under optimal water and nutrient regimens is related to someleaf and canopy photosynthetic characteristics. Three leaf photosyntheticcharacteristics are examined in detail: the light utilizationefficiency at normal ambient CO2 and O2 concentrations, a, therate of light saturated photosynthesis per unit leaf area, Fmax,and the ratio of the rates of photorespira tion and gross photosynthesis.The genetic variability in each of these characteristics issought from published data on a wide range of C3 and C4 planttypes. Within C3 and C4 plant types there are significant genetic differencesonly in Fmax,, although differences exist between C3 and C4plants in the other two characteristics. The effects of thesedifferences on the rate total dry matter production are estimated,and it is concluded that there is no compelling evidence toindicate that improvements in total dry matter production rates,in the U.K., are likely to result from genetic manipulationof these characteristics in the existing range of plant material.  相似文献   

8.
Anabaena flos-aquae A-37 was grown in bacteria-free cultureon a variety of nitrogen sources. Extracellular polysaccharideproduction was found to be a part of the normal metabolic processescausing the liberation of excess carbohydrates into the surroundingmedium rather than the result of cellular lysis. Non-adaptedcells supplied with NH4Cl produced abundant polysaccharide.However, the population did not increase. Cells adapted to NH4Clproduced smaller quantities of polysaccharide, but the populationdid increase. Polysaccharide production per cell was similaron Mg(NO3)2, KNO3, NaN03, NH4NO3, and NH4Cl. It was concludedthat an adequately utilized nitrogen source does not affectpolysaccharide production in A. flos-aquae A-37.  相似文献   

9.
Reduction kinetics of chloro- or methyl-substituted benzoquinones(BQs) in spinach PSII membrane fragments or n-heptyl-rß-D-thioglucoside-extractedPSII core complexes (HTG-PSII) was studied and compared to thatin cyanobacterial PSII core complexes [Satoh et al. (1995) PlantCell Physiol. 36: 597]. It was found that the BQs accept electronsat two sites (the QB and PQ sites) in the both spinach preparationsas in the cyanobacterial preparation. Maximum turnover rates(Vmax) and binding affinities (Km) of the two sites were estimated.Comparison of the values in PSII membrane fragments with thosein HTG-PSII showed that removal of the membrane structure orlight-harvesting chlorophyll a/b protein complexes from thePSII core complexes had little effect on the characteristicsof the QB site, indicating that the HTG-PSII have the intactQB site and are good materials to study the site. The Km andVmax values were comparable to those in the cyanobacterial preparation. Low affinity (high Km values) and high Vmax values of methyl-substitutedBQs to the QB site and almost the same rate of intrinsic electronflow through the QB site in the both spinach preparations furthersupport the hypothesis that the plastoquinone (PQ) moleculeat the QB site is not replaced by another PQ molecule but, afterreduction, only its head group goes out of the QB pocket, andcomes back after transferring the electrons and protons to afree PQ molecule [Satoh et al. (1993) Z. Naturforsch. 48c: 174]. (Received May 2, 1996; Accepted July 26, 1996)  相似文献   

10.
A strong correlation between the photosynthetic parameters Jmaxand Vcmax was found by Wullschleger (1993) in a survey of 109plant species. Measurements were made at various leaf temperatures,but the temperature dependence of Jmax and Vcmax differ. Oncevalues for Jmax and Vcmax in Wullschleger's analysis were adjustedto a common temperature, using an equation for the temperaturedependence of these parameters, the slope of the linear regressionfor Jmax versus Vcmax forced through the origin increased from1.97 to 2.68, and r2 increased from 0.79 to 0.87. Key words: Temperature, photosynthesis parameters  相似文献   

11.
BARCELO  A. ROS 《Annals of botany》1998,82(1):97-103
Production of hydrogen peroxide (H2O2) by the lignifying xylemof several vascular plants has been studied using a new histochemicalmethod based on the H2O2-dependent oxidation of 3,5,3'5'-tetramethylbenzidine(TMB) catalysed by cell wall peroxidases. This method allowsH2O2to be determined in the range of 5–100 µM, whereother methods, such as the KI/starch reagent, fail. With thismethod, it has been possible to determine H2O2production inthe lignifying xylem of a wide range of vascular plants (gymnospermsand angiosperms). The capability of xylem tissues of sustainingH2O2production lends support to the hypothesis that cinnamylalcohol polymerization in xylem vessels is caused by an H2O2-dependentoxidative coupling process.Copyright 1998 Annals of Botany Company H2O2generation, lignification, peroxidase, tetramethylbenzidine, xylem.  相似文献   

12.
Etiolated Avena sativa L. coleoptile sections were used to determinethe influence of C2H4 on in vivo and in vitro rates of CO2 fixation,and to measure the influence of various permutations of C2H4,CO2, and malate on growth. Whereas 1 mM malate or 320 µI-1 CO2 stimulated growth by approximately 100 per cent, inhibitionof growth by 10-8 µ I-1 C2H4 was substantial only in thepresence of malate or CO2 The increase in growth rate in responseto these two agents was eliminated by the simultaneous applicationof C2H4. The in vivo rate of dark [14C]bicarbonate fixationand in vitro enzymic assays of fixation were not measurablyinhibited by C2H4. These results are discussed in the lightof evidence which indicates that CO2-stimulated growth is mediatedby dark fixation. The data do not support the view that C2H4inhibition of growth results from an inhibition of fixation,but suggests that C2H4 may inhibit some step in the processby which malate stimulates growth.  相似文献   

13.
When Chlorella oulgaris ll h cells grown in air containing 4%CO2 (high-CO2 cells) were given low concentrations of14CO2 (<150ppm), the initial rate of photosynthetic 14CO2 fixation wasvery low and linear 14CO2 fixation was observed after an inductionperiod which lasted for ca. 45 min. No such induction period was observed when high-CO2 cells weregiven high concentrations of 14CO2 (10,000 ppm) or when IOW-CO2cells were given either low or high concentrations of 14CO2,supporting the observations by Briggs and Whittingham (l). However,irrespective of CO2 concentrations during growth and of 14CO2concentrations during the experiments, most of the 14C was incorporatedinto phosphate esters during the initial periods of photosynthetic14CO2 fixation. These results are in sharp contrast to the reportby Graham and Whittingham (4). 1 Requests for reprints should be addressed to S. Miyachi, RadioisotopeCentre, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan. (Received June 30, 1979; )  相似文献   

14.
利用Bac to Bac系统将意大利蜜蜂蜂毒磷脂酶A2(AmPLA2)基因cDNA克隆至转移载体pFastBacHTa中,得到pBacHT-AmPLA2,再将其转化入含穿梭载体Bacmid的受体大肠杆菌DH10Bac中,通过转座作用,得到含AmPLA2基因的重组病毒rBacmid-AmPLA2的DNA。提取其基因组DNA,用脂质体介导转染粉纹夜蛾细胞Tn-5B1-4,得到重组病毒rACV-Bac-AmPLA2。用此重组病毒感染Tn-5B1-4细胞, 在细胞中表达AmPLA2。SDS-PAGE电泳结果显示,与6×His Tag融合表达的产物蛋白分子量约为18 kD左右,表达量约占细胞总蛋白的5.35%。Western blot印迹显示,融合表达产物能与意大利蜜蜂蜂毒AmPLA2抗血清发生免疫反应。生物活性测定显示,含表达产物的细胞蛋白粗提物对底物蛋黄的酶活力约为6.13 μmol·min-1·mg-1。  相似文献   

15.
Varki  Ajit 《Glycobiology》1992,2(2):169
Fig. 1. The sialic acids. The nine-carbon backbone common toall sialic acids is shown. Natural substitutions described todate (at C4, C5, C7 C8, and C9,) are indicated. Additional diversityis generated by various types of glycosidic linkage (at R3)by generation of lactones (at C1 ), by dehydro forms (eliminatingR3), and anhydro forms diversity sialic acids neuraminic acids O-acetylation sialidase  相似文献   

16.
Cells of Dunaliella tertiolecta which had been grown in ordinaryair (low-CO2 cells) had high carbonic anhydrase (CA) activityon the cell surface and mainly utilized HCO3 for photosynthesis.When CA activity on the cell surface was inhibited by Diamoxor subtilisin, the cells utilized CO2. When bovine CA was added,the subtilisin-treated low-CO2 cells utilized mainly HCO3.When grown in air containing 2% CO2, the cells had low CA activityon the cell surface, and preferred CO2 to HCO3. Kineticanalysis of these results indicated that low-CO2 cells of D.tertiolecta absorb CO2 which was converted from HCO3via the CA located on the cell surface. (Received June 29, 1985; Accepted October 9, 1985)  相似文献   

17.
Legume symbioses such as pea, lucerne and clover exhibit a substantialdecline in nodular respiration and nitrogenase activity whensubjected to gas streams containing C2H2. Assuming a constantrate of O2 diffusion into the nodule this decrease in respiratoryO2 consumption would lead to an increase in internal O2 concentrationwhich would inactivate nitrogenase. No such inactivation hasbeen observed indicating that a change in diffusion resistanceis involved in the C2H2 response. Root nodules of C2H2 responsivesymbioses are distinguished by their tolerance to high (80 percent) O2 levels. The nitrogenase of soya-bean and sainfoin,which do not respond to added C2H2, is denatured at O2 levelsabove 40 per cent. Even in O2-tolerant systems (e.g. pea) theenzyme is damaged if the increase in O2 levels is rapid (ca.45 s) indicating that an induced change rather than a ‘permanent’feature is involved. The O2-tolerant, C2H2-responsive behaviourpattern of white clover nodules was reversed by pulse feedingwith nitrate-N indicating that the overall C: N ratio in thenodules is involved in determining the response.  相似文献   

18.
Sea water collected in mid-July was spiked with different combinationsof nutrients. Dissolved inorganic nitrogen (DIN) became exhausted,while significant amounts of P-PO4 and Si-SiO3 remained available.NH4 was taken up before NO3, but, in some cultures, NO3 uptakeappears to have started in the presence of  相似文献   

19.
Actinomycin D inhibited the elongation of epicotyl segmentsfrom azuki bean seedlings that was induced by simultaneous treatmentwith IAA and GA3. The drug also inhibited the elongation ofthe segments that was caused by IAA alone when it was appliedtogether with IAA. When the segments were pretreated with GA3and then incubated with IAA, GA3 promoted the elongation causedby IAA and brought about a predominance of transverse corticalmicrotubules (MTs) in the epidermal cells of the segments. Thechange in the arrangement of MTs caused by pretreatment withGA3 was evident 1 h after the start of subsequent incubationwith IAA when the effect of pretreatment with GA3 on the elongationhad not yet become apparent. Pretreatment with GA3 did not causeany change in the arrangement of MTs when GA3-pretreated segmentswere not incubated subsequently with IAA. Although actinomycinD applied before treatment with IAA did not inhibit the IAA-inducedelongation, the drug diminished the promotion of the elongationcaused by pretreatment with GA3 and prevented GA3 from bringingabout a predominance of transverse MTs when the drug was appliedduring the pretreatment with GA3. GA3-induced synthesis of mRNA seems to be involved in the promotionby GA3 of IAA-induced elongation and in the GA3-induced rearrangementof cortical MTs. (Received June 15, 1993; Accepted August 16, 1993)  相似文献   

20.
The seminal roots of N-free-grown barley seedlings were ableto take up NO3 immediately upon initial exposure; theuptake rate in the tip was half of that in the older root zones(middle and base). A lag of 60 min was required in all rootzones before the uptake rates started to increase during inductionwith external NO3. This increase could be prevented bythe addition of pFPA; we thus assume that additional NO3transport proteins were synthesized during NO3 induction.During the time-course of NO3 induction different uptakerates were measured in morphologically different regions ofthe tip (1 mm segments) indicating a regulation of NO3induction on a narrow local scale. In NO3 grown plants, NO3 uptake as well as NO3content increased basipetally along the root axis concomitantlywith increasing vacuolization of the cells. Although NO3uptake into the tip was only half of that into the older rootzones, this NO3 uptake was very important for the entireroot. Firstly, it provided the substrate for protein biosynthesisin the meristematic region: nitrate reductase activity and totalsoluble protein were highest in the first apical mm of the tip.Secondly, 3% of the NO3 taken up by the tip was foundin the base where it induced NO3 uptake: NO3 wastranslocated almost exclusively basipetally and as little as20nmolg1 root fr. wt. translocated from the tip weresufficient for acceleration of NO3 induction in the rootbase of N-free-grown plants. This clearly shows that the inductionof NO3 uptake does not depend exclusively on the availabilityof external NO3, but can be mediated also with internallytranslocated NO3.The root tip, therefore, may be consideredthe NO3 sensing region of the root. Key words: Barley, Hordeum vulgare L, internal NO3, NO3 uptake, root zones  相似文献   

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