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1.
According to the conventional glycolytic sequence [3,4-14C]glucoseyields phosphoenolpyruvate (PEP) labeled in position C-1. Thisyields pyruvate through pyruvate kinase reaction also labeledin C-1. Subsequent metabolism of pyruvate to acetyl CoA releasesradioactive carbon dioxide. Alternatively PEP may be convertedto oxalacetate by PEP carboxylase and then into organic andamino acids which retain the label. The procedure adopted wasto trap carbon dioxide evolved and isolate organic acids producedafter feeding [3,4-14C]glucose to developing soybean cotyledons.Under conditions of 27?C and pH of 7.5 and 8.5 about 60% ofthe glycolytic carbon was processed by pyruvate kinase and 40%by PEP carboxylase. At lower temperature (15?C) 60% of the carbonwas directed through the PEP carboxylase reaction. This maybe caused by cold lability of pyruvate kinase which was demonstratedin in vitro assays. Low pH, down to 5.5, reduced organic acidproduction by inhibition of PEP carboxylase activity. Pyruvatekinase was not affected and carbon dioxide evolution remainedconstant at varying pH. PEP carboxyiase and pyruvate kinaseindependently feed their products into two separate metabolicpools. Possibly they should jointly be considered as final enzymesin the glycolytic pathway of plants. (Received April 3, 1982; Accepted June 12, 1982) 相似文献
2.
Glucose, either uniformly labelled with14C, or specificallylabelled in the I, 2, or 6 position, was added to C. vulgaris.Radio-active carbon dioxide was produced initially ten timesfaster from glucose-I-14C than from glucose-6-14C. This differencewas found with carbohydrate-starved cultures, exponentiallygrowing cultures, and cultures assimilating ammonia or nitraterapidly. A similar difference was also found with C. pyrenoidosaand Ankistrodesmus. 37 per cent. of the 14C added as glucose-1-14Cto exponentially growing cells was recovered as carbon dioxidebut generally the recovery was less than this. Only 5 per cent.of 14C added as glucose-6-14C was recovered as carbon dioxide.The specific activity of the carbon dioxide produced was considerablylower than that of the carbon in the added glucose. 相似文献
3.
(±)(2-14C]ABA is metabolized by pea seedlings to phaseicand dihydrophaseic acids and conjugates and it is also reducedto the 1', 4'-trans-diol of ABA. This compound runs at the sameRF as the putative metabolite identified as 4'-desoxy ABA byTietz et al (1979). The 1', m4'-/trans-diol is dehydrated duringgas/liquid chromatography to 4'-desoxy ABA. No labelled zoneon the autoradiogram of the plant extract could be attributedto 4'-desoxy ABA so it is presumably an artefact formed by thedehydration of the 1', 4'-trans-diol of ABA. This probably occursin the injection port of the G. L.C. Key words: Plsum sativum, A. B.A., Metabolism, Phaseic/dihydrophaseic acids 相似文献
4.
The R- and S-enantiomers of racemic [2-14C]Me 1', 4'-cis-diolof abscisic acid have been separated by high performance liquidchromatography on an optically-active Pirkle column. R-[2-14C]-and S-[2-14C]abscisic acids, formed from the Me 1', 4'-cis-diolby oxidation and alkyline hydrolysis were fed to tomato shootsand the extracts analysed by reversed phase high performanceliquid chromatography. R-[2-14C]abscisic acid formed mainlythe abscisic acid glucose ester (ABAGE), abscisic acid l'-glucoside(ABAGS) and an uncharacterized conjugate. Dihydrophaseic acid4'-B-D-glucoside, the major metabolite of RS-abscisic acid intomato shoots, was found to be derived virtually exclusivelyfrom the natural, S-abscisic acid. Phaseic acid and conjugatesof abscisic acid were also found as products of the naturallyoccurring enantiomer. The resolution method was used to measurethe relative proportions of R and S enantiomers in the freeacid liberated from conjugates formed from RS-[2-14C]ABA fedto shoots. The ratios show an excess of the R-enantiomer: 5.8:1, ABAGE; 29.4: 1, ABAGE; 8.3: 1 for an uncharacterized conjugateand 6.1: 1 for the residual free [2-14C]ABA. Key words: ABA, HPLC, Tomato 相似文献
5.
Uptake of the dinitroaniline herbicide oryzalin (3,5-dinitro-N4,N4-dipropylsulfamlamide) and its effect on root growth werestudied using 5 mm corn (Zea mays L.) and pea (Pisum sativum)root apices. Pea root growth was much less susceptible to oryzalinthan corn root growth. Uptake studies showed that pea root apicesalso accumulated much less [14C]oryzalin and had a lower bindingaffinity for this herbicide. [14C]oryzalin was not metabolizedin root apices from either species. Thus, the differential susceptibilityto oryzalin in the case of corn versus pea can be explained,at least in part, by differences in oryzalin uptake and accumulationby roots. Oryzalin, dinitroaniline herbicides, Zea mays, Pisum sativum 相似文献
6.
Shelled green peas (ripening seeds of Pisum sativum var. Onward)were kept in the dark for 2 or 3 days in an atmosphere, eitherof air or 10 per cent carbon dioxide in air, containing 14CO2.Samples were removed at intervals, the acids of the T.C.A.C.extracted, estimated, and their content of 14C measured. Incorporationof 14C was mainly into the carboxyl carbon atoms of the acidswhich, with the exception of citrate, rose in specific activityrapidly for the first 46 h and then levelled off androse slowly for the rest of the experiment. The final valuesattained, again with the exception of C-6 of citrate, were muchbelow that of the tissue carbon dioxide. The cause of this failureto equilibrate with tissue carbon dioxide is discussed. Twomain carboxylation reactions are proposed, one from pyruvate(or other three carbon acid) to malate and the other from -oxoglutarateto oxalsuccinate and so to C-6 of citrate. The value of thevelocity constant of the first of these reactions was shownto be markedly decreased by increase in tissue carbon dioxidewhile that for the second carboxylation was unaffected. 14Cmoved into soluble amino-acids rapidly at first and then moreslowly; protein received 14C at a high rate throughout the experimentsmainly by isotopic exchange reactions. Calculations were madeof the rate of movement of carbon in the T.C.A.C. which wouldhave been required to give the observed changes in specificactivity of the metabolites but no scheme tested fitted allthe results satisfactorily. 相似文献
7.
《Journal of experimental botany》1968,19(2):219
Page 678, line 3, for [4-14C] read [I-14C] Page 678, line 4, for [I-14C] read [4-14C] Page 679, line 17, for C-I of malate read C-4 of malate Page 679, line 18, for C-4 of malate read C-I of malate 相似文献
8.
Grape leaves (Vitis labrusca L.) that are removed from the positionopposite the flower cluster either 28 or 14 days before anthesiscleave L-ascorbic acid (AA) at the C4-C5 bond into a C4 and,presumably, a C2 fragment. Leaves taken from this position 14days after anthesis fail to cleave AA. The C4 fragment is utilizedfor L(+)-tartaric acid (TA) biosynthesis while the C2 fragmentis recycled into hexose and products of the hexose metabolism.When [6-14C]AA is the source of the label, the sucrose-derivedglucose from labeled leaves has a distribution of 14C in thecarbon skeleton as follows: Cl, 35%; C2, 14%; C3, 4%; C(4+5),13% and C6, 34%. The effect of inhibitors of the glycolate pathwayon [6-l4C]AA metabolism is examined.
1This work was supported by Grant No. GM-22427 from the NationalInstitute of General Medical Science, National Institute ofHealth, United States Public Health Service, Bethesda, Maryland.This is Scientific paper No. 5305, Project 0266, College ofAgricultural Research Center, Washington State University, Pullman,WA 99164, U.S.A.
2Present address: The Radioisotope Research Center, Kyoto University,Kyoto 606, Japan. (Received August 29, 1979; ) 相似文献
9.
10.
Most of the 14C added as glucose to carbohydrate-starved cellsof Chlorella Vulgaris can be recovered as alcohol-soluble compoundsor as polysaccharide. Only 5I6 per cent., depending onthe position of 14C in the glucose supplied, is released ascarbon dioxide. Similar results were obtained with Chlorellapyrenoidosa and Ankistrodesmus. The labelled alcohol-solublecompounds in Chlorella vulgaris include amino-acids, particularlyglutamic acid, aspartic acid, and alanine, and, when glucose-I-14Cis metabolized, the amount of 14C recovered in these amino-acidsis about the same as that recovered as carbon dioxide. Degradationof the glucose incorporated into polysaccharide shown that theC1 and C6 atoms of glucose rapidly interchange when in the cells.The bearing of these results on attempts to estimate the relativeimportance of different pathways of glucose breakdown is discussed. 相似文献
11.
[14C]Sucrose, [14C]glucose and [14C]fructose were introducedinto potato tubers held at 10 °C and the redistributionof label chased over a 65 d period in storage. Respiratory losseswere identical in all treatments, as was the partitioning of14C between soluble and insoluble forms. Sucrose was the predominantlabelled sugar in the tubers after 20 h, regardless of the original[14C]sugar introduced, and was loaded and distributed throughoutthe tubers by the internal phloem system. After 20 h the proportionsof labelled sugars bore no relationship to those of the unlabelledendogenous sugars. However, with time the percentage of 14Cin sucrose fell while that in glucose increased and by 65 dthe proportions of the labelled sugars more closely resembledthe endogenous pools. Fructose represented a consistently lowproportion of both the labelled and unlabelled sugars. By 21d a considerable proportion of the soluble 14C had been convertedto starch (approx. 25% of the total tuber 14C), this value remainingrelatively constant for the remainder of the storage period.Sprouts which formed on the tubers contained up to 6% of thetotal tuber 14C but less than 0.2% of the tuber dry matter.It is suggested that the bulk of the translocated [14C]sucroseentered the symplast and exchanged slowly with the bulk of thesugars in the storage cell vacuoles. [14C]sugars, phloem loading, starch, potato tuber, Solunum tuberosum, cold storage 相似文献
12.
The metabolism of [8-14C]zeatin, supplied via micropipettesover a 24 h period to root nodules of Alnus gliutinosa (L.)Gaertn., was investigated. The major metabolites were tentativelyidentified by means of chromatographic, chemical, and enzymictreatments as adenine, adenosine, trans-zeatin riboside, dihydrozeatin,trans-zeatin-O-ß-D-glucoside, and the O-ß-D-glucosideof dihydrozeatin. In addition, a prominent water-soluble peakof radioactivity was present. This did not appear to be a ribosidebut was biologically active in the soybean callus test. The number and nature of the metabolites formed in the noduleswas similar in both dormant and non-dormant plants. 相似文献
13.
Silica gel thin layer chromatography showed that acetate-2-14C,pyruvate-3-14C and citrate-2,4-14C were incorporated into ipomeamaronein sweet potato root tissues infected by Ceratocystis fimbriata.Rates of incorporation of 14C, from these 3 substances, intothe CHCl3-CH3OH-soluble lipid fraction and ipomeamarone wereof the followingder: acetate > pyruvate > citrate
1This paper constitutes Part 82 of the Phytopathological Chemistryof Sweet Potato with Black Rot and Injury (Received December 11, 1969; ) 相似文献
14.
Metabolic patterns of some vascular plants (Dryas sp., Vacciniumsp., Salix sp., Alnus sp., Epilobium sp.), occurring in successionalhabitats, following acetate-2-14C incubations in the field weredemonstrated for the first time. Relative radioactivity withinthe alcoholic soluble fraction of each species reflects itsdistribution in successional communities. A high level of 14C-sugarswas present in the plants of the pioneer community; on the otherhand a high level of 14C-organic acids was present in the plantsof the forest community. Three patterns, based on the relativeactivities of the sugar- and organic acid-pools were noted whichcorrespond to the range and the frequency of occurrence of eachspecies in the successional stages. Only two types of 14C-aminoacid levels were noted corresponding to the range of distribution.Plants having less than 10% relative radioactivity in aminoacid-pools had a limited range of distribution and reside inonly one habitat; plants having more than 10% radioactivityshowed wider ranges of distribution occurring in at least twohabitats.
1 Contribution 292 of the Institute of Polar Studies, The OhioState University, Columbus, Ohio 43210. (Received April 16, 1975; ) 相似文献
15.
The uptake, transport and stability of ABA after foliar applicationto cucumber plants was studied using [2-14C] ABA. ABA uptakethrough uninjured epidermis of cucumber leaves appeared to bevery slow compared with the uptake through abraded leaves. Transportof [2-14C] ABA in the same system was also found to be veryslow. No metabolic changes in the absorbed [2-14C] ABA weredetected 24 hr after its application as checked by TLC and GLCtechniques. These results are compared and discussed in relationto previous reports.
1The Irene and David Schwartz Professor of Plant Genetics (Received April 26, 1976; ) 相似文献
16.
Technique for Simultaneous Determination of [35S]Sulfide and [14C]Carbon Dioxide in Anaerobic Aqueous Samples
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A technique for the simultaneous determination of [35S]sulfide and [14C]carbon dioxide produced in anaerobic aqueous samples dual-labeled with [35S]sulfate and a 14C-organic substrate is described. The method involves the passive distillation of sulfide and carbon dioxide from an acidified water sample and their subsequent separation by selective chemical absorption. The recovery of sulfide was 93% for amounts ranging from 0.35 to 50 μmol; recovery of carbon dioxide was 99% in amounts up to 20 μmol. Within these delineated ranges of total sulfide and carbon dioxide, 1 nmol of [35S]sulfide and 7.5 nmol of [14C]carbon dioxide were separated and quantified. Correction factors were formulated for low levels of radioisotopic cross-contamination by sulfide, carbon dioxide, and volatile organic acids. The overall standard error of the method was ±4% for sulfide and ±6% for carbon dioxide. 相似文献
17.
NONHEBEL H. M.; HILLMAN J. R.; CROZIER A.; WILKINS M. B. 《Journal of experimental botany》1985,36(1):99-109
Reverse-phase high-performance liquid chromatography was usedto analyse [14C]-labelled metabolites of indole-3-acetic acid(IAA) in coleoptile segments of Zeo mays seedlings. After incubationfor 2 h in 102 mol m3 [2-14C]IAA, methanolic extractsof coleoptiles contained between six and ten radioactive compounds,one of which co-chromatographed with IAA. The metabolic productsin coleoptile extracts appeared to be similar to those in rootextracts, with an oxindole-3-acetic-acid-like component as theprincipal metabolite, but the rate of metabolism was slowerin coleoptile than in root segments. Decarboxylation did notappear to play a major role in the metabolism of exogenous IAAduring the short incubation periods. Moreover, external IAAconcentration had little effect on the pattern of metabolism.Coleoptile segments were also supplied with [14C]IAA from agardonor blocks placed at the apical ends, and agar receiver blockswere placed at the basal ends. After incubation for 4 h, theidentity of the single radioactive compound in the receiverblocks was shown to be IAA by both reverse-phase high-performanceliquid chromatography and gas chromatography-mass spectrometrytechniques. Key words: Zea mays, Coleoptile, High-performance liquid chromatography, Indole-3-acetic acid 相似文献
18.
Excised cotyledons of Pinus radiata D. Don cultured under shoot-forming(plus benzyladenine) and non shoot-forming (minus benzyladenine)conditions for 10 and 21 days were fed U-[14C]-glucose for 3h in the light followed by a 3 h chase period. The labellingof individual metabolites as well as 14C incorporation intoprotein was assessed. It was found that the general metabolicpatterns were qualitatively the same in shoot-forming and nonshoot-forming conditions, however, metabolism leading to respirationas well as to the synthesis of some amino acids and proteinsynthesis was enhanced in the shoot-forming cultures. (Received February 16, 1987; Accepted July 8, 1987) 相似文献
19.
When 14CO2 was fed to flag leaf laminae at 20 d post-anthesis,the transport organs between the leaf and the grains containedappreciable 14C in glutamine, glutamate, serine, alanine, threonineand glycine. Smaller amounts of 14C were present in gamma-aminobutyricacid (GABA), aspartate and cysteine. Other amino acids whichwere labelled in the source leaf were not labelled in the transportorgans. The export of labelled glutamine, serine, glycine andthreonine from the source leaf was favoured in comparison tothe other amino acids mentioned. Threonine accumulated, andwas subsequently metabolised, in the rachis. [14C]GABA alsoaccumulated in the rachis. In the grains, the relative amountof soluble [14C]alanine increased with chase time. This wasprobably due to de novo synthesis and reflected the specialrole of alanine in grain nitrogen metabolism. Wheat, Triticum aestivum, 14CO2, amino acids, transport, carbon metabolism 相似文献
20.
In experiments using radioactive carbon dioxide (14CO2) a comparisonwas made of the 14C-photoassimilate translocation potentialsof two normal leaved (genotype AfAfTlTl) and two mutant formsof Pisum sativum (pea). A 14CO2 administration method is describedthat permitted 14C-translocation studies to be conducted underfield conditions. One of the mutants available produced tendrils in place of leaves(afafTlTl). The other mutant studied was without tendrils buthad a much branched petiole with numerous relatively minuteleaflets (afaftltl). These mutants and the normal-leaved cultivarswith which they were compared were not isogenic lines. Lengthybackcrossing would be required before full assessment couldbe made of the possible agronomic value of such mutations. An interim evaluation of these mutants was based on 14C-distributionassays that were conducted 48 h after feeding 14CO2, to specifiedleaves. The indication was that in translocation terms the leafand pod had a well defined respective source and sink relationshipthat was independent of leaf morphology. In each case the podswhich constituted the major 14C sinks depended on which leafhad been fed 14CO2. With regard to sink specific activity asdefined by the quantity of 14C incorporated per unit dry weightof pod, the mutants were not significantly different from normal. The implication of these findings was that fundamental changesin pea leaf morphology could be made genetically without a markedeffect on the photoassimilate export potential of the leaf. 相似文献