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1.
Comparison of the Arabidopsis thaliana vacuolar proton-pumpinginorganic pyrophosphatase with three F0F1-ATPase c-subunitsrevealed a strong similarity between a stretch containing aminoacids 227245 of the H+-PPase and a transmembrane a-helixof the c-subunits which contains the glutamate which binds N,N'-dicyclohexylcarbodiimide. (Received November 16, 1992; Accepted December 22, 1992) 相似文献
2.
Saeki Kazuhiko; Tokuda Ken-ichiro; Fujiwara Takeshi; Matsubara Hiroshi 《Plant & cell physiology》1993,34(2):185-199
Nucleotide sequencing of the region upstream of two ferredoxingenes, fdxC and fdxN, of Rhodobacter capsulatus revealed theexistence of one open reading frame (ORF), ORFU1,in the sameorientation as these genes and two other ORFs, ORFU2 and ORFU3,in the opposite orientation. Two potential 24/12promoters were found in front of ORFU1 and ORFU2, respectively,and there was a putative upstream activator sequence (UAS) orNifA-binding site between them. The ORFs corresponded to noknown nif genes. However, analysis of their putative productsshowed that the product of ORFU1 (Mr 47,912) and that of ORFU3(Mr 19,090) flavodoxin-like domain and a 2[4Fe-4S] ferredoxin-likedomain, respectively, and that the product of ORFU2 (Mr 20,424)was a hydrophobic protein with six potential membrane-spanningportions. Results of interposon mutagenesis and complementationexperiments indicated ORFU2 but not ORFU1 is essential for nitrogenfixation and that additional gene(s) essential nitrogen fixationmust be present in the unsequenced region adjacent to ORFU3.Translational fusion analysis involving lacZYA and fdxN or ORFU3provided evidence that the putative UAS responsible for regulationof both ORFUl-fdxC-fdxNand ORFU2-ORFU3 operons in opposite orientations,and that the control of the latter is stricter than that ofthe former. (Received August 19, 1992; Accepted November 16, 1992) 相似文献
3.
Oh-oka Hirozo; Kakutani Saki; Matsubara Hiroshi; Malkin Richard; Itoh Shigeru 《Plant & cell physiology》1993,34(1):93-101
The photoactive reaction center (RC) complex from the greensulfur bacterium Chlorobium limicola f. thiosulfatophilum, strainLarsen, was isolated after solubilization and ammonium sulfatefractionation followed by ion-exchange chromatography. The spectrumof the complex was almost identical with that of the similarRC complex isolated by Feiler et al. [(1992) Biochemistry 31:26082614] except for the presence of cytochrome c551instead of c553 in the latter study. A molecular ratio of BChla to P840 of the isolated RC complex was assayed to be 2535.SDSPAGE analysis revealed that the isolated complex containedthree major polypeptides with apparent molecular masses of 68,41 and 21 kDa, respectively. The 21-kDa polypeptide was identifiedto be a heme-binding protein by staining the gel for peroxidaseactivity. The cytochrome c551 was oxidized by flash light ina biphasic manner with half times of 90 and 390 µs, respectively,that coincided with the reduction half times of P840+. Threedistinct iron-sulfur centers assigned to FA, FB and Fx, respectively,from their g-values were detected by EPR spectroscopy at cryogenictemperature. These results suggest that the present preparationcontains a minimal functional unit of the RC of this bacterium,and that this complex appears to lie on a evolutionary linebetween RC's of purple bacteria and photosystem I. (Received August 18, 1992; Accepted October 28, 1992) 相似文献
4.
The Relation Between the Nitrogen Concentration and Photosynthetic Capacity of Potato (Solanum tuberosum L.) Leaves 总被引:1,自引:0,他引:1
Measurements of the rate of light-saturated photosynthesis (Pmax)were made on terminal leaflets of potato plants growing in cropssupplied with 0, 3, 6, 12, 24 and 36 g N m2. Measurementswere made between 100 and 154 d after planting. Two types ofleaf were selectedthe fourth leaf on the second-levelbranch (L4, B1) and the youngest terminal leaflet that was measurable(LYM). Later, the total nitrogen concentration of each leaflet(NL) was measured. A linear regression between Pmax and NL,common to both leaf positions, explained 68.5% of the totalvariation. With L4, B1 leaves there was a significant improvementin the proportion of variation explained when regressions withseparate intercepts and a common slope were fitted to individualfertilizer treatments. These results suggest that an increasingproportion of leaf nitrogen was not associated with the performanceof the photosynthetic system with increasing nitrogen supply.This separation between nitrogen treatments was not as clearfor LYM leaves. Stomatal conductance to transfer of water vapourwas neither influenced by leaf position nor directly by nitrogensupply. Rather conductance declined in parallel with the declinein photosynthetic capacity. Solanum tuberosum, potato, nitrogen, photosynthesis, stomatal conductance, leaf 相似文献
5.
The effects of nitrogen supply and cutting regime on the morphologicalcharacteristics (leaf appearance and expansion rates, leaf growthduration, leaf lifespan) of a cocksfoot sward were studied overthree growing seasons to gain a better understanding of thechanges in tiller characteristics (length and age of laminae,number of leaves per tiller) over time and in different seasons.We show that, for a given regrowth, the lamina expansion rateat the tiller level depended on herbage nitrogen status, butthe time course of its components differed according to nitrogensupply. When nitrogen was supplied, leaf appearance was fasterbut also decreased faster. In other words, the length of successivelaminae increased faster when nitrogen was supplied. The samewas true for the growth duration of the laminae and their lifespan.These changes resulted from the length of the sheaths from whichthe successive laminae emerged. As nitrogen increased cell number,it changed the ratio of lamina lengthn+1/sheath lengthnmorethan the ratio lamina lengthn/sheath lengthnat the same insertionlevel. Therefore sheath length increased faster and leaf appearancedecreased faster when nitrogen was supplied. This finding helpsto explain the effects of different heights and frequenciesof cutting in terms of their effects on sheath length. Copyright2000 Annals of Botany Company Nitrogen, defoliation, cocksfoot, sheath 相似文献
6.
Australia's tropical grasslands are dominated by C4grasses,characterized by their unique biochemistry and anatomy. Twonaturalized C4grasses (Panicum coloratum and Cenchrus ciliaris)were used to investigate whether high CO2partial pressure [p(CO2)] influences photosynthetic nitrogen use efficiency andplant nitrogen use efficiency (PNUE and NUE respectively). Plantswere grown for 30 d with four levels of N at p(CO2) of 38 or86 Pa. PNUE was calculated from leaf CO2assimilation rates (A)and leaf N concentrations, and NUE from total leaf N contentand plant dry mass. At each p(CO2), PNUE and NUE were greaterfor C. ciliaris than for P. coloratum due to higher A and drymass combined with lower leaf N concentrations. Elevatedp (CO2)increased PNUE of C. ciliaris only. This effect was due to lowerleaf N concentrations (area basis). At high p(CO2), NUE of C.ciliaris was also greater. This resulted from a 1.6-fold stimulationof dry mass by high p(CO2). Although dry mass of P. coloratumwas increased 1.2-fold by elevated p(CO2), its NUE was unaffected.Leaf transpiration rates were halved at elevated p(CO2), andwe suggest that this factor plays a major role in the growthresponse of C4grasses to high p(CO2). Copyright 2001 Annalsof Botany Company Panicum coloratum, Cenchrus ciliaris, nitrogen use efficiency, elevated CO2, leaf N concentration, growth, photosynthesis 相似文献
7.
Growth and Biomass Allocation, with Varying Nitrogen Availability, of Near-isogenic Pea Lines with Differing Foliage Structure 总被引:1,自引:0,他引:1
The single-gene mutation afila in pea (Pisum sativum L.) resultsin the replacement of proximal leaflets with branched tendrils,thereby reducing leaf area. This study investigated whethertheafila line could adjust biomass partitioning when exposedto varying nutrient regimes, to compensate for reduced leafarea, compared with wild-type plants. Wild-type and afila near-isogeniclines were grown in solution culture with nitrate-N added toinitially N-starved seedlings at relative addition rates (RN)of 0.06, 0.12, 0.15 and 0.50 d-1. The relative growth rate (RW)of the whole plants closely matched RNat 0.06 and 0.12 d-1,but higher RNresulted in a slightly higher growth rate. At agiven RN, the wild-type line had lower plant nitrogen statusthan the afila line. RWof the roots of the afila line was lessthan RWof the roots of the wild-type at the three higher ratesof N supply despite a greater accumulation of N in the rootsof the afila plants. Consequently, plant nitrogen productivity(growth rate per unit nitrogen) was lower for afila. Dry matterallocation was strongly influenced by nitrogen status, but nodifferences in shootroot dry matter allocation were foundbetween wild-type and afila with the same plant N status. Theseresults imply that decreased leaf area as a result of the single-genemutation afila affects dry matter allocation, but only accordingto its effect on the nitrogen status. Copyright 2000 Annalsof Botany Company Pisum sativum, pea, nitrogen limitation, growth, shootroot allocation, relative growth rate, nitrogen productivity, isolines 相似文献
8.
Cultures of the water fern Azolla pinnata R, Br. exposed for1 week to atmospheric NO2 (50, 100 or 200 nl l-1) induced additionallevels of nitrate reductase (NaR) protein and nitrite reductase(NiR) activity. At low concentrations of NO2 (50 nl l-1), nitratederived from NO2 provides an alternative N source for Azollabut does not affect rates of acetylene reduction. However, thesymbiotic relationship between Azolla and its endosymbiont,Anabaena azollae is only affected adversely by high concentrations(100 and 200 nl l-1) of atmospheric NO2. The resultant decreasesin rate of growth, nitrogen fixation, heterocyst formation,and overall nitrogen cycling are probably due to the additionalaccumulation of N products derived from higher levels of atmosphericNO2. Parallel increases in levels of polyamines suggest thatAzolla partially alleviates these harmful effects by incorporatingsome of the extra NO2-induced N into polyamines.Copyright 1994,1999 Academic Press Azolla-Anabaena symbiosis, nitrogen dioxide pollution, nitrogen metabolism, polyamines 相似文献
9.
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
10.
We have previously shown that inorganic orthophosphate (Pi)uptake by Catharanthus roseus cells proceeds by a proton/Picotransport mechanism [Sakano (1990) Plant Physiol. 93: 479]that acidifies the cytoplasm [Sakano et al. (1992) Plant Physiol.99: 672]. In the present study, we analyzed changes in the contentof endogenous organic acids, carbon dioxide evolution, and oxygenconsumption upon Pi application. The results are consistentwith the operation of the biochemical pH-stat mechanism [Davies(1986) Physiol. Plant. 67: 702] during and after Pi uptake. (Received November 13, 1997; Accepted March 30, 1998) 相似文献
11.
Yamakawa Seiyei; Watanabe Masao; Isogai Akira; Takayama Seiji; Satoh Shinobu; Hinata Kokichi; Suzuki Akinori 《Plant & cell physiology》1993,34(1):173-175
A cDNA clone encoding NS3-glycoprotein was isolated from stigmasof Brassica campestris. NS-glycoproteins correspond to the SLRI-glycoproteinsof B. oleracea and are highly conserved within the species.These data suggest that the NS-glycoproteins may play a rolein discrimination between species in the fertilization systemof Brassica. (Received September 4, 1992; Accepted November 9, 1992) 相似文献
12.
When grown in a nutrient solution containing combined nitrogen(NH4NO3), Lotus pedunculatus and L. tenuis seedlings inoculatedwith a fast-growing strain of Rhizoblum (NZP2037) did neitherdevelop root nodules nor develop flavolans in their roots. Incontrast, the roots of nodulated seedlings growing in a nitrogen-freenutrient solution contained flavolans. Flavolan synthesis coincidedwith root nodule development on these plants. When added as a single dose, high concentrations of NH4NO3 (5and 10 mg N per plant) stimulated the growth of L. pedunculatusplants but suppressed nodulation and nitrogen fixation. In contrastthe continued supply of a low concentration of NH4NO3 (1?0 mgN d1 per plant) stimulated nitrogen fixation by up to500%. This large increase in nitrogen fixation was associatedwith a large increase in nodule fresh weight per plant, a doublingof nodule nitrogenase activity, and a lowering of the flavolancontent of the plant roots. The close relationship between nitrogendeficiency, nodule development, and flavolan synthesis in L.pedunculatus meant that it was not possible (by nitrogen pretreatmentof plants) to alter the ineffective nodule response of a Rhizobiumstrain (NZP2213) sensitive to the flavolan present in the rootsof this plant. 相似文献
13.
Striga hermonthica is a root hemiparasitic angiosperm nativeto the African semi-arid tropics. It is a major weed of C4 cerealsbut locally it is also an important weed of the C3 plant, rice[Oryza sativa). Infected rice plants produced 17% and 42% ofthe total biomass of uninfected plants when grown at two differentammonium nitrate concentrations, 1 and 3 mol m3, respectively.S. hermonthica prevented grain production at both concentrationsof nitrogen. At the lower concentration no heads were produced.At the higher concentration head weight was only 6% of uninfectedcontrols. S. hermonthica also altered the partitioning of drymatter between plant parts, such that shoot growth was reducedto a greater extent than root growth. As a consequence the root-to-shootratio of infected plants was approximately five times greaterthan that of uninfected control plants. Light saturated ratesof photosynthesis In infected plants were 56% and 70% of thoseof uninfected controls, at low and high nitrogen, respectively.Infection also led to lower values of stomatal conductance althoughthe substom-atal CO2 concentration was unaffected. Analysisof the response of photosynthesis to substomatal CO2 concentration(A/CI curves) demonstrated that lower rates of photosynthesiscould not be solely attributed to lower stomatal conductances.Lower initial slopes and asymptotic rates suggest that bothcarboxylation and processes controlling regeneration of ribulose-1,5-bisphosphate are reduced by infection. The data are discussedwith respect to the influence of S. hermonthica on the growthand photosynthesis of C4 hosts, where in contrast to the situationwith rice, nitrogen feeding results in a marked alleviationof the effects of the parasite on the host. Key words: Rice, Striga, growth, photosynthesis, nitrogen 相似文献
14.
Experiments were carried out to investigate the long-term influenceof humidity on the short-term responses of stomata and CO2 assimilationto vapor pressure difference in Oryza sativa (rice, C3 species)and Panicum maximum (green panic, C4 species). Plants were grownfor four weeks in growth chambers set at 35% and 85% relativehumidity at 25C air temperature, 38+2 Pa CO2 partial pressureand 1,700µmol m-2s-1 photon flux density. Soil was saturatedwith water in both humidity treatments. Low humidity pretreatmentscaused low leaf conductance and low rates of transpiration andCO2 assimilation in O. sativa, but small changes in stomatalresponses to humidity and in CO2 assimilation were found inP. maximum. From the short-term gas exchange experiments, itwas noted that the responsiveness of leaf conductance to vaporpressure difference were affected by humidity pretreatmentsin O. sativa, whereas unaffected in P. maximum. In O. sativameasurements of CO2 assimilation as a function of internal CO2partial pressure (A-Ci curve) indicated that low humidity pretreatmentsreduced the CO2 assimilation at high internal CO2 partial pressure,but the initial slope of the A-Ci curve was unaffected. Furthermore,plant characteristics such as total dry weight and leaf areaof plants subjected to low umidity were lower than plants subjectedto high humidity. The reductions in O. sativa, however, werelarger than in P. maximum. Stomatal frequency from low humiditygrown plant was higher than that from high humidity grown plantsin both species although there is no significant difference.The data indicated that if the short term inhibition of netCO2 assimilation at a high vapor pressure difference was imposedduring vegetative growth, the photosynthetic biochemistry andthe resultant plant growth were largely depressed in O. sativa,a C3 species. (Received May 26, 1992; Accepted November 2, 1992) 相似文献
15.
Uptake of 13C and 15N (ammonium, nitrate and urea) by Microcystis in Lake Kasumigaura 总被引:1,自引:0,他引:1
The uptake rate of carbon and nitrogen (ammonium, nitrate andurea) by the Microcystis predominating among phytoplankton wasinvestigated in the summer of 1984 in Takahamaira Bay of LakeKasumigaura. The Vmax values of Microcystis for nitrate (0.0250.046h1) and ammonium (0.150.17 h1) were considerablyhigher than other natural phytoplankton. The ammonium, nitrateand urea uptake by Microcystis was light dependent and was notinhibited with nigh light intensity. The K1 values were farlower than the Ik values. The carbon uptake was not influencedby nitrogen enrichment. Microcystis accelerated the uptake rateby changing Vmax/K s value when nitrogen versus carbon contentin cells declined. Nitrate was scarcely existent in TakahamairiBay during the summer, when Microcystis usually used ammoniumas the nitrogen source. However, the standing stock of ammoniumin the water was far lower than the daily ammonium uptake rates.Therefore, the ammonium in this water had to be supplied becauseof its rapid turn-over time (0.72.6 h). 相似文献
16.
From homogenates prepared from surface-sterilized nodules ofseedlings of Casuarina cunninghamiana grown aeroponically, astrain of Frankia designated HFPCc13 was isolated and has beengrown in pure filamentous culture in a defined synthetic nutrientmedium. Vesicle and sporangium formation can be induced by removalof combined nitrogen from the medium.Frankia strain HFPCc13nodulates young seedlings of C. cunninghamiana and C. equisetifoliawithin three weeks of inoculation with an optimum root mediumpH of 67 for nodulation and optimum temperature of 3035°C. The presence of combined nitrogen in the root mediuminhibits nodulation with NH4+ more inhibitory than NO3.Frankia HFPCc13 does not nodulate Allocasuarina species withinthe same family nor several other possible actinorhizal plantstested. Thus this strain is quite precise in its host specificity.The rate of acetylene reduction was greater in C. cunninghamianathan the closely related species C. equisetifolia. In neitherof these host species were vesicles observed to occur withinthe infected root nodules which had been demonstrated to beactively fixing dinitrogen. Root nodules were shown to be activein acetylene reduction over a range of O2 concentration in thegaseous environment with an optimum at about 20 per cent O2,the ambient PO2 of the air. The mechanism(s) for oxygen protectionof nitrogenase within the filamentous form of Frankia withinthese nodules remains to be explained. Casuarina, Frankia, nodulation, nitrogen fixation 相似文献
17.
The growth of Polygonum cuspidatum in sand culture was analysedunder varying nutrient conditions. Nitrogen availability influencednitrogen uptake of plants through the uptake rate per unit rootweight rather than the amount of root. In turn, the differentamounts of nitrogen taken up affected plant growth through theireffects on the rate of leaf expansion. Net assimilation rate (NAR) increased with nitrogen contentper unit leaf area (C), but further increase in leaf nitrogencaused diminishing returns of NAR Optimal nitrogen content perunit leaf area (Copt) to maximize dry-matter production of aleaf could be determined by drawing a tangent from the onginto a curvilinear relation between NAR and C. This optimal contentdivides a nitrogen-limiting range (C < Copt) from a carbon-limitingone (C> Copt) along the axis of nitrogen content. Under nitrogenlimitation, efficiency of nitrogen use in dry-matter productioncould increase if the plant had a larger carbon sink. This givesa qualitative explanation to reduced shoot-to-root ratio underlimited availability of nitrogen. Polygonum cuspidatum Sieb. et Zucc, Japanese knotweed, carbon sink, growth analysis, leaf nitrogen, net assimilation rate, nitrogen use efficiency 相似文献
18.
Unno Keiko; Ando Ichiro; Hagima Naoko; Yokogaki Shuichi; Koike Chieko; Okada Shoji 《Plant & cell physiology》1992,33(7):963-969
The effects of deuterium (D) on Chlorella ellipsoidea C-27 wereinvestigated. Cells grown in a medium prepared with deuteriumoxide (D2O) showed pronounced delays in cell growth and division;the length of a cell cycle in medium with 100 mol% D2O was morethan 5 times longer than that in medium prepared in H2O Thedelay caused by D2O was not overcome by either indoleaceticacid or kinetin. The biological and ultrastractural characteristicsof deuterated .Chlorella (D-Chlorella) cells were examined.The responses of D-Chlorella to cell wall-digesting enzymesdid not differ from those of normal (H-Chlorella) cells. D-Chlorellacells were enlarged, and cellular components, such as proteins,nucleic acids, lipids and ATP, were present in larger quantitiesthan those in H-cells. The chloroplast of D-Chlorella was enlarged,but the levels of component photosynthetic pigments were significantlyreduced. By contrast, mitochondria of D-Chlorella were smallerthan those of H-cells. These changes in levels of cellular componentsand in the sizes of organelles seem to be unique to deuteration. (Received May 13, 1992; Accepted July 28, 1992) 相似文献
19.
Scots pine (Pinus sylvestris L.) seedlings were grown for 3years in the ground in open top chambers and exposed to twoconcentrations of atmospheric CO2(ambient or ambient + 400 µmol mol-1) without addition of nutrients and water. Biomassproduction (above-ground and below-ground) and allocation, aswell as canopy structure and tissue nitrogen concentrationsand contents, were examined by destructive harvest after 3 years.Elevated CO2increased total biomass production by 55%, reducedneedle area and needle mass as indicated, respectively, by lowerleaf area ratio and leaf mass ratio. A relatively smaller totalneedle area was produced in relation to fine roots under elevatedCO2. The proportion of dry matter in roots was increased byelevated CO2, as indicated by increased root-to-shoot ratioand root mass ratio. Within the root system, there was a significantshift in the allocation towards fine roots. Root litter constituteda much higher fraction of fine roots in trees grown in the elevatedCO2than in those grown in ambient CO2. Growth at elevated CO2causeda significant decline in nitrogen concentration only in theneedles, while nitrogen content significantly increased in branchesand fine roots (with diameter less than 1 mm). There were nochanges in crown structure (branch number and needle area distribution).Based upon measurements of growth made throughout the 3 years,the greatest increase in biomass under elevated CO2took placemainly at the beginning of the experiment, when trees grownin elevated CO2had higher relative growth rates than those grownunder ambient CO2; these differences disappeared with time.Symptoms of acclimation of trees to growth in the elevated CO2treatmentwere observed and are discussed. Copyright 2000 Annals of BotanyCompany Elevated CO2, Pinus sylvestris, biomass production, allocation, fine roots, root litter, crown structure, nitrogen, C/N ratio 相似文献
20.
Shortening velocity and myosin heavy- and light-chain isoform mRNA in rabbit arterial smooth muscle cells 总被引:1,自引:0,他引:1
In smooth muscle cells (SMCs)isolated from rabbit carotid, femoral, and saphenous arteries, relativemyosin isoform mRNA levels were measured in RT-PCR to test forcorrelations between myosin isoform expression and unloaded shorteningvelocity. Unloaded shortening velocity and percent smooth muscle myosinheavy chain 2 (SM2) and myosin light chain 17b(MLC17b) mRNA levels were not significantly different insingle SMCs isolated from the luminal and adluminal regions of thecarotid media. Saphenous artery SMCs shortened significantly faster(P < 0.05) than femoral SMCs and had more SM2 mRNA(P < 0.05) than carotid SMCs and lessMLC17b mRNA (P < 0.001) and higher tissuelevels of SMB mRNA (P < 0.05) than carotid and femoralSMCs. No correlations were found between percent SM2 and percentMLC17b mRNA levels and unloaded shortening velocity in SMCsfrom these arteries. We have previously shown that myosin heavy chain(MHC) SM1/SM2 and SMA/SMB and MLC17a/MLC17b isoform mRNA levels correlate with protein expression for these isoforms in rabbit smooth muscle tissues. Thus we interpret these results to suggest that 1) SMC myosin isoform expression andunloaded shortening velocity do not vary with distance from the lumenof the carotid artery but do vary in arteries located longitudinally within the arterial tree, 2) MHC SM1/SM2 and/orMLC17a/MLC17b isoform expression does notcorrelate with unloaded shortening velocity, and 3)intracellular expression of the MHC SM1/SM2 and MLC17a/MLC17b isoforms is not coregulated. 相似文献