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1.
Blue light effects on the acclimation of energy partitioningcharacteristics in PSII and CO2 assimilation capacity in spinachto high growth irradiance were investigated. Plants were grownhydroponically in different light treatments that were a combinationof two light qualities and two irradiances, i.e. white lightand blue-deficient light at photosynthetic photon flux densities(PPFDs) of 100 and 500 µmol m–2 s–1. The CO2assimilation rate, the quantum efficiency of PSII (PSII) andthermal dissipation activity / in young, fully expanded leaves were measured under 1,600 µmol m–2 s–1white light. The CO2 assimilation rate and PSII were higher,while / was lower in plants grown under high irradiancethan in plants grown under low irradiance. These responses wereobserved irrespective of the presence or absence of blue lightduring growth. The extent of the increase in the CO2 assimilationrate and PSII and the decrease in / by high growth irradiance was smaller under blue light-deficient conditions. These resultsindicate that blue light helps to boost the acclimation responsesof energy partitioning in PSII and CO2 assimilation to highirradiance. Similarly, leaf N, Cyt f and Chl contents per unitleaf area increased by high growth irradiance, and the extentof the increment in leaf N, Cyt f and Chl was smaller underblue light-deficient conditions. Regression analysis showedthat the differences in energy partitioning in PSII and CO2assimilation between plants grown under high white light andhigh blue-deficient light were closely related to the differencein leaf N.  相似文献   

2.
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   

3.
The decay kinetics of tyrosine Z (Yz) in Tris-treated PhotosystemII particles were measured by time-resolved EPR at differentpH values (pH 5.5 to 7.5) between 230 and 297 K. Yz inducedby laser flashes decayed in a biphasic wav; t values were about100 ms in the fast phase and about 1 s in the slow one, respectively,at room temperature. The fast phase was attributed to a recombinationof charges on Yz and QA. The activation energies forthe reaction of Yz with QA between 245 and 297 K havebeen estimated to be more than 38 kJ mol–1 at pH (>6.5)and less than 32 kJ mol–1 at pH (<6.0), respectively.The activation energy gap between high pH (>6.5) and lowpH (<6.0) ranges was found to be E=4.4 kJ mol–1. Judgingfrom the fact that pH 6.2 appears to be the border between thehigh and low pH regions, we suggest that the kinetics of Yzis strongly influenced by the dissociation of the nearby histidineresidue. (Received February 21, 1997; Accepted June 24, 1997)  相似文献   

4.
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   

5.
The effect of a pure preparation of substance-IA (S-IA) whoseamino acid sequence is identical to that of one of the factorpeptides (2), on sexual agglutinability and DNA synthesis wascomparatively studied. The optimum concentration of S-IA forthe induction of sexual agglutinability of cells of an inducible strain was 1 ng/ml. The inducing action of S-IA was detectedin 20 min and reached a maximum in 60 min. Only 8.7% inhibitionof DNA synthesis by S-IA in the same strain was detected in1 hr and 40.4% inhibition in 2 hr at a concentration of 1 µg/ml.These results suggest that the primary action of the peptidyl sex fractor on a mating-type cells is the induction of sexualagglutinabiity. (Received October 25, 1977; )  相似文献   

6.
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   

7.
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   

8.
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   

9.
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   

10.
A cell-free ethylene-forming system of Pseudomonas syringaepv.phaseolicola (Kudzu strain) was characterized by its psychrophilictrait. Ethylene was most effectively produced from -ketoglutaricacid (-KG) at 0.5 mM followed by glutamate and then istidineat 5 to 10 mM. The presence of FeSO4 was essential to the cell-freesystem. DTT and histidine greatly stimulated ethylene production;the latter could be substituted to some extent by its analogues.The optimum pH value and temperature for the ethylene-formingreactions were pH 7.0 and 25?C, respectively. Ethylene formationfrom -KG was inhibited in the presence of carbonates or organicacids of the TCA cycle, whereas that from glutamate was inhibitedin the presence of ammonium salts. Ethylene production from-keto--methylthiobutyric acid in the cell-free system was largelydependent on non-enzymical processes in the presence of DTTand FeSO4. The ethylene-forming reactions were inhibited completelyby 1 mM n-propyl gallate and 1 mM p-chloromercuribenzoic acidand partly by coenzymes such as pyridoxal-1-phosphate, folicacid, and flavin mononucleotide at 5mM. The complete systemfor the highest ethylene production consisted of: 0.5 mM -KG,50 mM HEPES (pH 7.0), 5 mM DTT, 0.5 mM FeSO4, and 10 mM histidine.The amount of ethylene produced in this system was equivalentto 40 to 50% of that produced by the living cells. (Received October 22, 1986; Accepted January 19, 1987)  相似文献   

11.
We analyzed the chlorophyll fluorescence parameters in a 3Dcellular arrangement in vivo by using a modified Nipkow disk-typeconfocal laser scanning microscope (CLSM). We first definedthe 3D values of PSII (photochemical yield of PSII) and NPQ(non-photochemical quenching) in mesophyll, epidermal and guardcell chloroplasts from the leaf surface to several tens of micronsin depth. We also used this CLSM method to analyze the relationshipsbetween actinic light intensity and the chlorophyll fluorescenceparameters for Boston fern and broad bean leaf specimens. Asthe actinic light intensity increased, the mean PSII valuesdecreased and the NPQ values increased in all chloroplasts ofBoston fern and broad bean leaf. These values differed withcell type and species. The Boston fern chloroplasts had lowerPSII values than the broad bean chloroplasts, and vice versafor the NPQ values. The PSII values of Boston fern chloroplastsdecreased in the order mesophyll, epidermal and guard cell chloroplasts.The NPQ values decreased in the order guard cell, mesophylland epidermal chloroplasts, except at 12 µmol m–2s–1 actinic light, when the mesophyll value was slightlylower than that of the epidermis. The trend in the PSII andNPQ values of broad bean mesophyll and guard cell chloroplastswas opposite to that of Boston fern chloroplasts. As 3D CLSMcan provide the PSII and NPQ values of each chloroplast in a3D cellular arrangement, this method has potential for investigatingdifferences in the functions of chloroplasts in vivo.  相似文献   

12.
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   

13.
Enzymatic Degradation of Chlorophyll in Chenopodium album   总被引:3,自引:0,他引:3  
The breakdown of chlorophyll (Chi) in crude extracts of Chenopodiumalbum (white goose foot) in the dark was examined. Derivativesof pheophorbide were formed when Chi or chlorophyllide wasincubated with depigmented crude extracts. The formation ofpheophorbide was completely prevented by heat treatment of extracts,indicating that the reaction was enzymatic, and the presenceof a Mg-releasing enzyme, the so called Mg-dechelatase, waspostulated. This hypothesis was strongly supported by the observationthat the formation of pheophorbide was inhibited by 51% by 10mM MgCl2. Analysis by high-performance thin-layer chromatography(HPTLC) and liquid chromatography (HPLC) showed that the appearanceof chlorophyllide , pheophorbide 132-hydroxychlorophyllide and pyropheophorbide was accompanied by a concomitant decreasein levels of Chi The formation of 132-hydroxychloro-phyllide was not clearly an enzymatic reaction and requires furtherexamination. It appears that Chl is degraded in a crude extractof C. album via the following enzymatically catalyzed reactions (Received September 10, 1990; Accepted November 15, 1990)  相似文献   

14.
Hypocotyl growth of seedlings of dark-grown squash (Cucurbitamaxima Duch.) was greatly reduced by the addition of 60mM polyethyleneglycol (PEG) to hydroponic solution (water stress). Apoplastic solution (A) and cell sap (C) were separately collectedfrom the hypocotyl segments by a centrifugation method. Theosmotic potentials of A (A) and C (c), and (=cA) ofstressed hypocotyls were always lower than those of unstressedhypocotyls. Suction force was measured by immersing the segments into solutionsof different concentrations of mannitol. Suction force was significantlycorrelated with C (r= –0.99). The mechanical properties of the cell wall of hypocotyl segmentswere measured by stressrelaxation technique. Minimum stressrelaxation time (To), relaxation rate (R) and residual stressof unstressed hypocotyls were low during the growth period andincreased when the growth ceased. To and R of stressed hypocotylsdecreased one day after the stress treatment, but the residualstress was not decreased by the water stress throughout theexperiment. These results suggest that the suppressed growth of dark-grownsquash hypocotyls under water stress was due neither to thereduction of the osmotic potential difference between innerand outer space of the cell, nor to the decrease in suctionforce, but was partly due to the unchanged mechanical propertiesof the cell wall, as represented by one stress-relaxation parameter,residual stress. (Received February 5, 1988; Accepted September 8, 1988)  相似文献   

15.
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   

16.
The effect of premature drying on the sensitivity of aleuronelayer cells of developing barley (Hordeum vulgare L.) grainto gibberellic acid (GA3) was investigated. The capacity ofbarley aleurone layer cells to respond to GA3, as indicatedby -amylase synthesis and secretion by de-embryonated grain,increased during the later stages of development. Aleurone layersof immature grain (younger than 30 d after anthesis; DAA) werenot capable of producing amylase in response to GA3; however,premature drying at this stage promoted GA-responsiveness resultingin the induction of mRNA for -amylase and increased -amylasesynthesis and secretion. Preincubation of the immature grainor its maintenance at 100% relative humidity prior to exposureof the de-embryonated grain to GA3 also led to an enhanced capacityof the aleurone layer to produce amylase and its mRNA as comparedto the fresh, untreated grain. However, the amount of mRNA andenzyme produced was much lower than that induced by prematuredrying. Moreover, following these nondrying treatments, thealeurone layer cells remained unresponsive to exogenous GA3;the same amount of enzyme was produced in the absence of appliedGA3. Transient expression of chimeric gene constructs in aleuronelayer cells of de-embryonated grain suggest that drying up-regulatesthe -amylase gene promoter in response to GA3. We conclude thatdesiccation is required for barley aleurone layer cells to becomeresponsive to GA3 and hence express their full potential foramylase synthesis and secretion. 3Present address: Department of Biochemistry, University ofMissouri, 117 Schweitzer Hall, Columbia MO 65211, U.S.A.  相似文献   

17.
The possibility that gibberellin-induced -amylase synthesisin barley endosperm might be mediated by cyclic-3',5'-adenosinemonophosphate (3',5'-AMP) was examined. Promotion of -amylasesynthesis by 3',5'-AMP (5 mM) was observed in the absence ofgibberellic acid (GA3) and in combination with GA3 at concentrationsbelow 2 mµM. When combined with gibberellin at concentrationsabove 2 mµM, however, 3',5'-AMP reduced the amount of-amylase obtained. The cyclic nucleotide showed slight activityat concentrations as low as 0.05 mM. These promotions were shownto be due to increased synthesis of -amylase rather than toan increased secretion of the enzyme. Of a variety of adeninecompounds and nucleoside diphosphates tested only 3',5'-AMPand adenosine diphosphate (ADP) induced -amylase synthesis.Longer incubation times were necessary to obtain maximal -amylaseinduction with the nucleotides than with GA3. ADP and 3',5'-AMPwere about one third and one fifth as active, respectively,as GA3 in promoting -amylase synthesis, although GA3 was morethan 107 times more effective. AMO-1618 did not inhibit theaction of the nucleotides and methanolic extracts of the nucleotidesshowed no gibberellin-like activity. Both nucleotides were synergisticwith GA3 in overcoming the inhibitory effects of acetate andcitrate buffers on -amylase synthesis. (Received February 24, 1969; )  相似文献   

18.
Eleven different types of bacteria were isolated which werecapable of growing on -caprolactam, the monomeric material fornylon 6 polyamide, as the sole source of both carbon and nitrogen. The optimal concentration of -caprolactam for the bacterialgrowth was about 0.6% in a synthetic liquid medium enrichedwith a small amount of yeast extract. The bacterial strains grew also on -butyrolactam, -valerolactamand the -amino acids corresponding to these lactams and -caprolactam.Ammonium adipate was a good substrate for the growth of allthe strains. One strain of Corynebacterium aurantiacum was found to be capableof utilizing cyclic and linear oligomers of 6-aminocaproic acidwith an exception of cyclic dimer. The strains of corynebacteria required vitamin B1 for growth. Metabolism of -caprolactam and related compounds is discussedbriefly. (Received September 9, 1965; )  相似文献   

19.
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   

20.
Rhizoid differentiation in Spirogyra I. Basic features of rhizoid formation   总被引:1,自引:0,他引:1  
Several types of rhizoids occurring in the process of differentiationin Spirogyra sp. are described and their interrelation was elucidated.There are two differentiation sequences: PpPRhros or PpPRhrodRhros(for explanation of abbreviations see p. 533), although undersome conditions the sequences ceased halfway through. The initiationtime for rhizoid formation had no relation to the cell cyclestage. The difference in growth patterns between the rhizoidand ordinary filament cells was demonstrated with Calcofluor-stainingand centrifugation. The optimum temperature and pH of the culture medium for rhizoiddifferentiation were 20?C and pH 7, respectively. A contactstimulus was not necessary for induction. Of the several environmental factors examined, light was themost important, for rhizoid formation, since a rhizoid was inducedonly when light was given after cutting the filament. (Received December 14, 1972; )  相似文献   

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