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1.
Variability of the amplification factor of light absorption by filter-retained aquatic particles in the coastal environment 总被引:3,自引:0,他引:3
Tassan Stelvio; Ferrari Giovanni Massimo; Bricaud Annick; Babin Marcel 《Journal of plankton research》2000,22(4):659-668
The amplification of light absorption by aquatic particles retainedon glass-fiber filters, the so-called ß factor, has beenmeasured for 29 stations located in the varying coastal environmentof the northern basin of the Adriatic Sea. The spectral valuesof the optical density of particles have been determined onglass-fiber filters by the standard transmittance (T) methodas well as by the transmittance-reflectance (T-R) method, whichperforms an accurate correction for light backscattering bythe particles, and on glass slides by the modified filtertransferfreeze(FTF) method, which eliminates the pathlength amplification.It has been shown that the relationships between the opticaldensities of particles on glass slides (ODsus) and on glass-fiberfilters (ODf) have a low dispersion when ODf is measured bythe T-R method: in this case, the use of a single expressionfor all stations adds an error that does not exceed the typicaluncertainty of the measurement of the filter-retained particleabsorption. On the contrary, the ODsus versus ODf plots obtainedby the T method exhibit considerable variability, apparentlydue to the approximate correction for light backscattering performedby this method, and do not permit the use of a single equationfor all stations. 相似文献
2.
The optical pathlength amplification (ß factor), inducedby multiple scattering in glass-fibre filters used for lightabsorption measurements of aquatic particles, has been measuredby the transmittance-reflectance (T-R) method for algal specieswith cell diameter in the range from 1 to 5 µm. Theßfactors obtained showed a much lower dispersion than that observedin similar measurements carried out by the standard transmittancemethod, suggesting that this could be due, at least in part,to the incomplete account of the scattering losses taken bythe latter method. An experimental test has verified that theß factor expression derived from measurements carriedout by the T-R method on an algal culture is also applicableto detrital particles. 相似文献
3.
A sensitivity analysis of the 'Transmittance-Reflectance' method for measuring light absorption by aquatic particles 总被引:7,自引:0,他引:7
A thorough sensitivity analysis of the TransmittanceReflectance(T-R) method for measuringin vivo light absorption by aquaticparticles retained on glass-fiber filters has been carried out.Particular attention has been devoted to the error contributionby the variability of the optical properties of the GF/F filtersused. The overall error of the measurement of the filter-retainedparticle optical density, ODs, has been evaluated as ~0.002(1), with 0.0015 error contribution by the filter variability.The corresponding error of the optical density of the particlesuspension, ODsus, has been obtained by differentiation of theequation expressing the experimental correlation (ODsusversusODs); the error increases with the optical density value, from= 0.0015 (for ODsus = 0.05) to = 0.027 at the upper limit ofthe optical density range tested (ODsus = 0.59). The validityrange of the experimental (ODsus versus ODs) correlation hasbeen shown to extend to ODs = 0.75. The importance of the accuratecorrection for light backscattering performed by the T-R methodhas been investigated by comparison with results given by thestandard Transmittance (T) method; it has beenshown that the coarse correction for light scattering includedin the T method may cause serious errors in the measured opticaldensity spectra of mineral detritus. This evidence confirmsthe need to resort to the T-R method for the measurement ofparticle samples of detritus-rich coastal waters. The papersummarizes the latest developments of the T-R method and includesan Appendix with asynopsis of the routine now used by the authors. 相似文献
4.
MUSCHINEK GYORGYI; ALSCHER RUTH; ANDERSON LOUISE E. 《Journal of experimental botany》1987,38(6):1069-1075
Muschinek, G., Alscher, R. and Anderson, L. E. 1987. The sensitivityof light modulation of enzyme activity to arsenite and sulphiteand of photosynthetic induction to arsenite is determined bya cytoplasmic geneJ. exp. Bot. 38: 10691075. The membrane component of the light modulation system was moresensitive to arsenite and to sulphite in the Pisum cultivarNugget than in the cultivar Progress No.9. Likewise, the induction phase of CO2 fixation wasmore arsenite sensitive in chloroplasts isolated from Nuggetplants. Sensitivity was controlled by a cytoplasmic gene. Key words: Induction, light modulation, arsenite sensitivity 相似文献
5.
Vessel element formation in cultured carrot-root phloem slices 总被引:2,自引:0,他引:2
The effects of light, auxin and cytokinin on vessel elementformation in phloem slices of carrot root were examined. When slices of carrot cultivars, Nakamura-senko-futoand Yamada-hyakunichisenk6- naga, preculturedin the dark on modified Murashige and Skoog's medium for twodays were cultured on a medium containing 5x106 M 2,4-Din the dark, no vessel element formation occurred. When preculturedslices were cultured in the light with 5x106M 2,4-D,vessel element formation was remarkable. But when 5x107Mkinetin, benzyladenine or zeatin was added, vessel elementswere readily formed even in the dark. When slices were cultured in the light, a cytokinin-like substance(s)that causes vessel element formation was produced in the slices,then was released to the medium. The substance(s) was fairlystable to heat. In slices of carrot cultivars, kuroda-gosun, Kintokiand Kokubu-senk6-6naga, a different result forvessel element formation was obtained. When slices of thesecultivars were cultured on a medium containing 5x106M2,4-D in the dark, vessel element formation was remarkable.It seemed, therefore, that these cultivars contain enough ofa cytokinin-like substance(s) to form vessel elements. In fact,vessel element forming activity was found in the alcohol extractof carrot root phloem from these cultivars. (Received June 8, 1971; ) 相似文献
6.
The metabolic fate of [U-14C]sucrose in suspension culturesof Catharanthus roseus cells was monitored for 96 h after thecells were transferred to fresh complete (+Pi)or to phosphate-deficient Murashige and Skoog (Pi)medium. Sucrose was hydrolysed extracellularly to glucose andfructose. The rate of uptake of sugars by the cells was 1.53times higher in +Pi culture than in Piculture. Little difference in the rate of incorporation of radioactivityinto the ethanol-soluble fraction was found between the +Piand Pi cultures during the initial 24h of culture, but after 48 h the rate in +Picultures was higher than that in Pi cultures.Incorporation of radioactivity into ethanol-insoluble macromoleculeswas always significantly higher in the cells in +Picultures than in those in Pi cultures.The results suggest that Pi strongly affects the utilizationof sugars by cultured plant cells through the stimulation oftransport of sugars as well as through the activation of metabolism. Catharanthus roseus, Madagascar periwinkle, suspension culture, inorganic phosphate, sucrose, transport, metabolism 相似文献
7.
Covariance adjustment of survival curves based on Cox's proportional hazards regression model 总被引:1,自引:0,他引:1
Lee James; Yoshizawa Carl; Wilkens Lynne; Lee H. P. 《Bioinformatics (Oxford, England)》1992,8(1):23-27
Cox's proportional hazards regression model is a useful statisticaltool for the analysis of survival data from longitudinalstudies. This multivariate method compares the survivalexperience between two or more exposure groups whileallowing for simultaneous adjustment of confounding due to oneor more covariates. In addition to the summary regression statistics,further insight on the exposureresponse relationshipcan be gained by visually examining the covariatesadjustedsurvival curves in the respective comparison groups. Covariatesadjustedsurvival curves are usually computed by the average covariatemethod. This method is, however, subject to potentialdrawbacks. A method that avoids these drawbacks is to estimateadjusted survival curves by the corrected group prognostic curvesapproach. We have written a computer program to construct survivalcurves by the latter method. The program is coded in the InteractiveMatrix Language of SAS. 相似文献
8.
Pith callus tissues were grown under continuous blue (450 mµ),green (545 mµ), red (650 mµ), and white(full-spectrum) light, and in the dark for 22 days at 27±2°C at energy levels of 15,000 ergs cm2 sec1. Mean increases in fresh weight of tissues grown under whiteand blue light were significantly greater than those of tissuesgrown in green and red light and in the dark. Tissues grownin the dark yielded mean fresh weight increases significantlylower than tissues grown under blue, red, and whitelight. No significant differences were shown between blue andwhite, red and green, and green and dark treatmentsrespectively. Cell differentiation occurred in all treatmentsonly to the extent of vessel element formation. There were nodifferences in degree of differentiation between treatments. It was proposed that the high-energy reaction of photomorphogenesiswas in operation in the Pelargonium callus tissue. The resultsindicated the presence in the tissue of high-energy photoreceptor(s).The use of high-intensity, incandescent illumination for experimentalprocedures approximating natural conditions of irradiation wasindicated as desirable for pith callus tissues of Pelargoniumzonale var. Enchantress Fiat. 相似文献
9.
The back cover of this book states that contrary to theclaims of the nativists, research shows that man-dispersed speciesincrease biological diversity, benefit ecosystems, and act asan important force for healing the planet. This is anuncompromising statement, and David Theodoropoulos divides hisdevelopment of the arguments supporting this statement intothree parts. Part I (Chapters 16) is Nature, Dispersaland Reaction. Part II (Chapters 7 and 8) is Why?Psychology, Politics and Pseudoscience. Part III (Chapters911) is Humanity and Diversity. There isalso an Introduction including a summary of findingsand An outline for a new theory of anthropogenic dispersal, 相似文献
10.
Voigt Jurgen; Liebich Ines; Hinkelmann Bettina; Kierss Michael 《Plant & cell physiology》1996,37(1):91-101
To identify precursors of the insoluble glycoprotein frameworkof the Chlamydomonas cell wall, a polyclonal antibody was raisedagainst the mixture of polypeptides released from the insolublewall fraction by chemical deglycosylation. This antibody preferentiallycross-reacted with a 150 kDa salt-soluble cellwall glycoprotein. The conclusion that this 150 kDaglycoprotein is a putative precursor of the insoluble cell wallfraction was corroborated by the results of pulse-chase experimentsand by experiments with antibodies raised against the 150kDa salt-soluble glycoprotein and against its 100 kDadeglycosylation product, respectively. Whereas the antibodyagainst the 150 kDa glycoprotein preferentiallyrecognized carbohydrate side chains, the antibody against its100 kDa deglycosylation product was found to have essentiallythe same specificity towards glycosylated and deglycosylatedcell wall components as the antibody against the deglycosylationproducts of the insoluble wall fraction. Furthermore, the antibodyagainst the deglycosylated, insoluble wall fraction recognizedalmost the same set of peptide fragments derived by V8 proteasetreatment from the 150 kDa salt-soluble cell wallglycoprotein and its 100 kDa deglycosylation product, respectively,as the antibody against the 100 kDa deglycosylated cell wallpolypeptide. (Received April 22, 1994; Accepted November 21, 1995) 相似文献
11.
Welbaum G.E.; Bian D.; Hill D.R.; Grayson R.L.; Gunatilaka M.K. 《Journal of experimental botany》1997,48(3):643-654
The freezing tolerance of many plants, such as pea (Pisum sativum),is increased by exposure to low temperature or abscisic acidtreatment, although the physiological basis of this phenomenonis poorly understood. The freezing tolerance of pea shoot tips,root tips, and epicotyl tissue was tested after cold acclimationat 2C, dehydration/rehydration, applications of 104M abscisic acid (ABA), and deacclimation at 25C. Tests wereconducted using the cultivar Alaska, an ABA-deficientmutant wil, and its wildtype. Freezinginjury was determined graphically as the temperature that caused50% injury (T50) from electrical conductivity. Endogenous ABAwas measured using an indirect enzyme-linked immunosorbant assay,and novel proteins were detected using 2-dimensional polyacrylamidegel electrophoresis. The maximum decrease in T50 for root tissuewas 1C for all genotypes, regardless of treatment. For Alaskashoot tips and epicotyl tissue, exogenous ABA increased thefreezing tolerance by 1.5 to 4.0C, while coldtreatment increased the freezing tolerance by 7.5 to14.8C. Cold treatment increased the freezing toleranceof shoot tips by 9 and 15C for wiland wild-type, respectively. Cold acclimationincreased endogenous ABA concentrations in Alaskashoot tips and epicotyls 3- to 4-fold. Immunogold labeling increasednoticeably in the nucleus and cytoplasm of the epicotyl after7 d at 2C and was greatest after 30 d at the time of maximumfreezing tolerance and soluble ABA concentration. Cold treatmentinduced the production of seven, three, and two proteins inshoot, epicotyl, and root tissue of Alaska, respectively.In Alaska shoot tissue, five out of seven novelproteins accumulated in response to both ABA and cold treatment.However, only a 24 kDa protein was produced in wiland wild-type shoot and epicotyl tissues aftercold treatment. Abscisic acid and cold treatment additivelyincreased the freezing tolerance of pea epicotyl and shoot tissuesthrough apparently independent mechanisms that both resultedin the production of a 24 kDa protein. Key words: Pisum sativum, cold acclimation, immuno-localization 相似文献
12.
Simulated swards of each of two selection lines of Lolium perennecv. S23 with fast and slow ratesof mature tissue respiration were establishedin growth rooms at 20/15 °C day/night temperatures and studiedover four successive regrowth periods of 46, 30, 26 and 53 daysduration. The slow line outyielded the fast,both in harvestable shoot (above a 5 cm cut) and in root andstubble. Its advantage increased over successive regrowth periodsto 23 per cent (total biomass). Gas analysis measurements onthe entire communities (including roots), during the final regrowthperiod, showed that the slow line had a 2234per cent lower rate of dark respiration per unit dry weight.This enabled it to maintain its greater mass of tissue for thesame cost in terms of CO2 efflux per unit ground area. Halfthe extra dry weight produced by the slow line,relative to the fast, could be attributed to itsmore economic use of carbon. The rest could be traced to a 25per cent greater tiller number which enabled the slowline to expand leaf area faster (though not at a greater rateper tiller), intercept more light and fix more carbon, earlyin the regrowth period. Lolium perenne L., ryegrass, respiration, maintenance respiration, tiller production, simulated swards, canopy photosynthesis, carbon economy 相似文献
13.
Developmental control of xylem hydraulic resistances and vulnerability to embolism in Fraxinus excelsior L.: impacts on water relations 总被引:3,自引:0,他引:3
Welbaum G.E.; Bian D.; Hill D.R.; Grayson R.L.; Gunatilaka M.K. 《Journal of experimental botany》1997,48(3):655-663
The freezing tolerance of many plants, such as pea (Pisum sativum),is increased by exposure to low temperature or abscisic acidtreatment, although the physiological basis of this phenomenonis poorly understood. The freezing tolerance of pea shoot tips,root tips, and epicotyl tissue was tested after cold acclimationat 2C, dehydration/rehydration, applications of 104M abscisic acid (ABA), and deacclimation at 25C. Tests wereconducted using the cultivar Alaska, an ABA-deficientmutant wil, and its wildtype. Freezinginjury was determined graphically as the temperature that caused50% injury (T50) from electrical conductivity. Endogenous ABAwas measured using an indirect enzyme-linked immunosorbant assay,and novel proteins were detected using 2-dimensional polyacrylamidegel electrophoresis. The maximum decrease in T50 for root tissuewas 1C for all genotypes, regardless of treatment. For Alaskashoot tips and epicotyl tissue, exogenous ABA increased thefreezing tolerance by 1.5 to 4.0C, while coldtreatment increased the freezing tolerance by 7.5 to14.8C. Cold treatment increased the freezing toleranceof shoot tips by 9 and 15C for wiland wild-type, respectively. Cold acclimationincreased endogenous ABA concentrations in Alaskashoot tips and epicotyls 3- to 4-fold. Immunogold labeling increasednoticeably in the nucleus and cytoplasm of the epicotyl after7 d at 2C and was greatest after 30 d at the time of maximumfreezing tolerance and soluble ABA concentration. Cold treatmentinduced the production of seven, three, and two proteins inshoot, epicotyl, and root tissue of Alaska, respectively.In Alaska shoot tissue, five out of seven novelproteins accumulated in response to both ABA and cold treatment.However, only a 24 kDa protein was produced in wiland wild-type shoot and epicotyl tissues aftercold treatment. Abscisic acid and cold treatment additivelyincreased the freezing tolerance of pea epicotyl and shoot tissuesthrough apparently independent mechanisms that both resultedin the production of a 24 kDa protein. Key words: Pisum sativum, cold acclimation, immuno-localization 相似文献
14.
During the growth of Isochrysis galbana, several non-proteinamines may be detected in the growth medium. Of these, one (termedTTl) accumulates in proportion to the numbersof cells present. The concentrations of TTl, andof another (termed TA), are 35 times higherin cultures in which Isochrysis is predated by Oxyrrhis marina.The lowest estimates of the concentration of extracellular TTlare an order of magnitude higher than those of any protein aminoacid. Of the protein amino acids, some like glycine are utilizedduring predation while others, like histidine, accumulate inthe medium Because of the unknown N-content and reactivity ofthe non-protein amines during HPLC, it is not possible to sayif these compounds (together with other components of dissolvedorganic N) form a significant proportion of the unaccountedfor N in the system after predatory activity. During predationin the absence of detectable free ammonium (when Isochrysismay be expected to be N-deprived), particles accumulate in themedium. Most of these are <2.5 µ.m in diameter andare suggested to be remains of digested prey. There is evidenceof a reassimilation of these particles by prey-deplete Oxyrrhis. 相似文献
15.
A Cytochrome P450 Mediated Naringenin 3'-Hydroxylase from Sweet Orange Cell Cultures 总被引:1,自引:0,他引:1
Doostdar Hamed; Shapiro Jeffrey P.; Niedz Randall; Burke M.D.; McCollum T. Gregory; McDonald Roy E.; Mayer Richard T. 《Plant & cell physiology》1995,36(1):69-77
A microsomal flavonoid 3'-hydroxylase (F3'H) catalyzing themetabolism of naringenin to eriodictyol in Citrus sinensis (L.)Osbeck cv. Hamlin cell suspension cultures wasshown to be a cytochrome P450 enzyme. This reaction requiredO2 and NADPH and was inhibited by CO, with partial reversalof CO-inhibition by light at 450 nm. Cytochrome P450 contentranged from 1020 pmol (mg microsomal protein)1.The F3'H reaction was shown to be linear in regard to proteinconcentration between 2.5 and 25 µg of microsomal protein.The optimum pH for the reaction was 7.47.6 and the temperatureoptimum was between 30 and 37°C. The apparent Km and Vmaxfor naringenin were 24 µM±3.2 and 81.4±7.9pmol eriodictyol min1 (mg protein)1, respectively.The microsomal F3'H was also capable of forming dihydroquercetinfrom dihydrokaempferol (40 pmol min1 (mg protein)1)and of quercetin from kaempferol (3.25 pmol min1 (mgprotein1). Cytochrome c and ketoconazole were the bestinhibitors of WH activity followed by piperonyl butoxide anda-naphthoflavone. Light was shown to be an inducer of the F3'Halmost doubling the specific activity and increasing the microsomalcytochrome P450 content by 30% over that of dark grown cells.F3'H activity was also confirmed in microsomal preparationsof young (new flush) leaves from Hamlin treesand flavedo of Hamlin oranges, Marshgrapefruit, and Lisbon lemon. No activity wasobserved in older, hardened leaves and albedo of all the fruittested. Initiation of embryogenesis in the Hamlincell suspension cultures by switching from a sucrose mediumto a glycerol-based medium resulted in the down-regulation ofF3'H.
1Mention of a trademark, warranty, proprietary product, or vendordoes not constitute a guarantee by the U.S. Department of Agricultureand does not imply its approval to the exclusion of other productsor vendors that may also be suitable. 相似文献
16.
Effect of Cultivar, Temperature and Seed Size on the Germination and Emergence of Soya Beans (Glycine max (L.) Merr.) 总被引:2,自引:0,他引:2
The rapid and uniform establishment of soya bean [Glycine max(L.) Merr.] stands is conducive to higher yields. This studywas undertaken to determine the effects of cultivar, temperature,and seed size on the rate of germination and emergence. No cultivar effect on the germination rate was observed. However,in an emergence study from a sand-soil-peat mixture, cultivardifferences in emergence rates were noted(Chippewa 64> Wayne > Amsoy 71). In anotheremergence study (sand media) the cvs Calland andWilliams emerged faster than the cv. 'Wayne orWells. Time required for 50 per cent germination decreased (18.84.0days) as the temperature increased from 10 to 30 °C (5 °Cincrements). Emergence (50 per cent) from a sand-soil-peat mixturewas more rapid (19.86.3 days) as the simulated plantingdate (growth chamber set to simulate field temperatures) wasdelayed from 16 April to 15 June with an intermediate date of16 May. In addition, time required for 50 per cent emergence of thecultivars from sand decreased (79376 h) as the temperaturewas increased from 10 to 30 °C with no decrease from 30to 35 °C. Seed size effects were apparent, with the very small seed germinatingslower than the three larger seed sizes. In the emergence studieswith both the sand and sand-soil-peat mixture there was a generaltrend toward more rapid emergence with the smaller seeds. However,the absolute differences were small. Significant cultivar x temperature interactions were observedfor the germination and emergence rates. In most cases the cultivarsmerged in terms of germination and emergence rates at temperaturesbetween 10 and 20 °C and at the higher temperatures thecultivar rankings were different from those observed at temperaturesbelow the merging point. Glycine max (L.) Merr, soya bean, seed germination, establishment of seedlings 相似文献
17.
The Nitrogen Content of Plants and the Self-thinning Rule of Plant Ecology: A Test of the Core-skin Hypothesis 总被引:3,自引:0,他引:3
The core-skin hypothesis postulates that secondarilythickened plants behave energetically as an inert corecovered by an active skin, the skinbeing two-imensional, the core three-dimensional.This would explain the self-thinning or3/2 rule of plant ecology, that is, the tendencyfor log (dry weight per plant) and log (number of plants perunit area) to progress along a straight line relationship, withslope = 3/2. The hypothesis was tested as follows. Plant nitrogen contentwas used as an estimate of the mass of skin perplant, and dry weight as an estimate of the mass of the core.As plants mature the slope of the relationship between y = log(mass of nitrogen per plant) and x = log (mass of dry matterper plant) is expected to decline from an initial value of 1.0towards a final value of 0.66. The intercept of the relationshipis expected to reflect the intrinsic content of skinper unit of core. Genotypic variation in thisparameter should cause genotypic differences in the maximumattainable yield of biomass per unit area. The expectations were investigated by fitting the function y= p+qx+r exp x to 30 sets of data on plant nitrogencontent, plant weight and time in 18 different vegetables. Simplelinear regressions of y on x were fitted to more limited setsof data on weights and nitrogen contents of mature trees. Theexpectations were, with some minor exceptions, confirmed. Nitrogen, yield, plant competition, self-thinning 相似文献
18.
《Journal of experimental botany》1977,28(6):1247
Effects of coupled solute and water flow in plant roots withspecial reference to Brouwer's experiment. Edwin L. Fiscus. p. 71 Abstract: Line 3 delete interval insertinternal. p. 73 Materials and Methods: line 6: delete diversion insert division line 9 equation should read Jv=Lp PRT(C0C1). 74 Last line of figure legend: 101 should read 1011. 75 Line 11: delete seems insert seem. le 1 column heading106 should read 1011. 77 delete ...membrane in series of... insert membranein series or... Delete final paragraph. 相似文献
19.
Pattern of Respiration of a Perennial Ryegrass Crop in the Field 总被引:3,自引:0,他引:3
Dark respiratory losses of CO2 were measured ona one year old sward of S24 perennial ryegrass (Lolium perenneL.) at intervals during a 74 day reproductive growth period,between April and June, and a 21 day vegetative growth period,in July and August. Part of the sward was shaded for one weekbefore measure ments commenced. Measurements of darkrespiration continued for 46 hand it was possible to distinguishtwo components which are designated maintenanceand synthetic Maintenance respiration was taken to be the meanrate of CO2 efflux after 4046 h darkness. When calculatedon a plant d. wt basis at 15°C it ranged between 6 to 32mgCO2 g-1 day-1 during reproductive growth and 1014 mgCO2 g-1 day-1 during vegetative growth. During reproductivegrowth, sward protein content ranged between 723 percent and when maintenance respiration was recalculated on thebasis of protein content it changed relatively little throughoutthe growth period (90140 mg CO2 g pro tein-1 day-1);the value for vegetative growth ranged between 70100mgCO2 g protein-day-1. Total synthetic CO2 flux was determined duringreproductive growth and a rate of synthetic CO2flux was determined during both reproductive and vegetativegrowth. Between 15 and 35 per cent of the CO2 fixed in the previousphotoperiod was lost in synthetic respirationof above-ground material in reproductive swards. Previous shadingincreased the proportion of synthetic CO2 lossfrom above ground. The rate of synthetic CO2 outputduring the first hours of darkness increased with amount ofCO2 fixed in the previous photoperiod, although it was not proportionalto it. There is some evidence that assimilate is carried-overfrom one photoperiod to the next. 相似文献
20.
Effect of Inorganic Phosphate on the Biosynthesis of Purine and Pyrimidine Nucleotides in Suspension-Cultured Cells of Catharanthus roseus 总被引:1,自引:0,他引:1
The levels of purine and pyrimidine nucleotides in suspensioncultures of Catharanthus roseus were determined 24 h after stationary-phasecells were transferred to fresh complete (+Pi)or phosphate-deficient (Pi) Murashige-Skoogmedium. The levels of ATP, GTP, UTP and CTP were from approx.3 to 5-fold greater in the cells grown in +Pimedium than in the cells grown in Pi medium.The levels of almost all other nucleotides were slightly higherin the cells in +Pi medium. The rates of de novoand salvage biosynthesis of purine and pyrimidine nucleotideswere estimated from the rates of incorporation of radioactivityfrom [14C]formate, [214C]glycine, NaH14CO3, [614C]orotate,[814C]adenine, [814C]adenosine, [214C]uraciland [214C]uridine. The results indicated that the activityof both the de novo and the salvage pathway was higher in thecells in +Pi medium than in the cells in Pimedium. The rate of degradation estimated from the rate of releaseof 14CO2 from labelled purines and pyrimidines indicated thatdegradation of uridine was significantly reduced in the cellsin +Pi medium, but no significant difference wasfound in the degradation of adenine, adenosine and uracil. Thepossible role of Pi in the control of the biosynthesis of nucleotidesand in the degradation of uridine is discussed. Catharanthus roseus, Madagascar periwinkle, suspension culture, inorganic phosphate, nucleotides, purines, pyrimidines, biosynthesis, degradation 相似文献