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1.
Spinach chloroplasts catalyzed ATP formation from acetyl phosphateand ADP when exposed to light. No ATP formation was detectablein the dark. In the absence of ADP, chloroplasts did not hydrolyzeacetyl phosphate in the light or dark. Neither high-energy phosphatessuch as creatine phosphate and phosphoenol pyruvate nor inhibitorsof photophosphorylation competitive with Pi, such as ß-naphthylmonophosphate, phenyl phosphate and pyridoxal 5-phosphate, couldsubstitute for acetyl phosphate as a Pi donor. The apparentKm values for acetyl phosphate and Pi were 0.81 mM and 0.25mM, respectively. The maximal rate of ATP formation with acetylphosphate and Pi were 331 and 521 µmol ATP formed mg chl–1hr–1, respectively. The optimum pH value for acetyl phosphate-dependentATP formation was about 8.0. NH4Cl, dicyclohexylcarbodiimideand triphenyltin chloride inhibited the acetyl phosphate-dependentATP formation. Acid-base transition also could induce subsequentATP formation from acetyl phosphate and ADP. These results suggestthat the acetyl phosphate-dependent ATP formation requires theformation and the utilization of a proton-motive force as ordinaryphotophosphorylation does. 1 This work was supported in part by Grants-in-Aid for ScientificResearch from the Ministry of Education, Science and Culture,Japan to H. S. Part of this work was reported at the 1981 AnnualMeeting of the Japanese Society of Plant Physiologists (Sapporo,May 8, 1981). (Received August 25, 1981; Accepted November 1, 1981)  相似文献   

2.
The role of nitric oxide (NO) in the occurrence of intracellular Ca2+ concentration ([Ca2+]i) oscillations in pituitary GH3 cells was evaluated by studying the effect of increasing or decreasing endogenous NO synthesis with L-arginine and nitro-L-arginine methyl ester (L-NAME), respectively. When NO synthesis was blocked with L-NAME (1 mM) [Ca2+]i, oscillations disappeared in 68% of spontaneously active cells, whereas 41% of the quiescent cells showed [Ca2+]i oscillations in response to the NO synthase (NOS) substrate L-arginine (10 mM). This effect was reproduced by the NO donors NOC-18 and S-nitroso-N-acetylpenicillamine (SNAP). NOC-18 was ineffective in the presence of the L-type voltage-dependent Ca2+ channels (VDCC) blocker nimodipine (1 µM) or in Ca2+-free medium. Conversely, its effect was preserved when Ca2+ release from intracellular Ca2+ stores was inhibited either with the ryanodine-receptor blocker ryanodine (500 µM) or with the inositol 1,4,5-trisphosphate receptor blocker xestospongin C (3 µM). These results suggest that NO induces the appearance of [Ca2+]i oscillations by determining Ca2+ influx. Patch-clamp experiments excluded that NO acted directly on VDCC but suggested that NO determined membrane depolarization because of the inhibition of voltage-gated K+ channels. NOC-18 and SNAP caused a decrease in the amplitude of slow-inactivating (IDR) and ether-à-go-go-related gene (ERG) hyperpolarization-evoked, deactivating K+ currents. Similar results were obtained when GH3 cells were treated with L-arginine. The present study suggests that in GH3 cells, endogenous NO plays a permissive role for the occurrence of spontaneous [Ca2+]i oscillations through an inhibitory effect on IDR and on IERG. voltage-gated potassium channels; ether-à-go-go-related gene potassium channels; slow-inactivating outward currents; fast-inactivating outward currents  相似文献   

3.
The Effect of Temperature on Leaf Appearance in Rice   总被引:10,自引:3,他引:10  
Temperature is the principal environmental determinant of cropleaf appearance. The objective of this study is to analyse whetherthere are different effects of day temperature (TD) and nighttemperature (TN) on main-stem leaf appearance in rice (OryzasativaL.). Plants of 12 rice cultivars were grown at five constant temperatures(22, 24, 26, 28 and 32 °C) and four diurnally fluctuatingtemperatures (TD/TN: 26 /22, 30 /22, 22 /26 and 22 /30 °C)with a constant photoperiod of 12hd-1. The leaf appearance onthe main stem was measured. A constant change in leaf appearance rate was observed duringontogeny. The relation between the number of emerged leavesand days from seedling emergence was described by a power-lawequation with only one cultivar-specific parameter. Values forthis parameter were estimated for the five constant temperaturetreatments, and the relation between this parameter and temperaturewas quantified by a nonlinear model. Leaf appearance for thefour fluctuating temperature treatments could be accuratelypredicted on the basis of these relations in each cultivar.This indicated that there were no specific effects ofTDandTNonleaf appearance in rice, in contrast with phenological developmentto flowering. The optimum temperature for leaf development wasfound to be substantially higher than for development to flowering. The final main-stem leaf number differed with diurnal temperatureconditions. When a diurnal temperature delayed flowering, itincreased the leaf number as well. This might explain whyTDandTNhada different effect on development to flowering but not on leafdevelopment. Oryza sativa; rice; leaf appearance; leaf number; day and night temperature  相似文献   

4.
The synergistic effects of 2-ethyl-3-methoxycarbonyl-l-(p-tolylcarbamoyl)-isoureaand 4-ethoxy-l-(p-tolyl)-s-triazine 2,6(1H,3H)-dione on GA1,3,4,7,8,9,17,19,20ana 53 in rice seedlings were investigated. Each synergist showeda very high effect when combined with GA1,3,9 or 17, a higheffect with GA4,7,19 or 20, little effect with GA53, and noeffect with GA8. (Received July 22, 1981; Accepted October 2, 1981)  相似文献   

5.
The influence of temperature on photosynthesis and transpirationwas studied in ten varieties of Lolium perenne, L. multiflorum,Dactylis glomerata, and Festuca arundinacea from three climaticorigins grown in three different controlled environments (15?C, 72 W m-2 visible irradiation, 16-h photoperiod; 25 ?C, 72W m-2 visible irradiation, 16-h photoperiod; and 25 ?C, 180W m-2 visible irradiation, 16-h photoperiod) and in the glasshousein July/August. The optimum temperature for photosynthesis was influenced primarilyby growth environment; growth at low temperature (15 ?C) resultedin a low optimum temperature, which differed little from varietyto variety. The maximum CO2-exchange rate was influenced bygrowth environment and by variety. Within a variety, plantsgrown at higher light intensity or lower temperature had a greaterCO2-exchange rate. Seven varieties showed a negative correlationbetween the optimum leaf temperature and the maximum CO2-exchangerate. Activation energies for photosynthesis were influencedby growth environment only. There were marked varietal differences in the values of leafresistances (ra + rt) obtained from transpiration data at theoptimum leaf temperature for CO2 exchange. In Lolium, and Dactylisthe Mediterranean varieties had higher leaf resistances thanthe Northern varieties with the maritime varieties intermediate.In general the Dactylis varieties had higher resistances thanthe corresponding Lolium and Festuca varieties. Only at highgrowth temperatures was (ra+rl) insensitive to temperature;otherwise an activation energy of about 10 kcal/mole was observed.A negative correlation was found between mean varietal diffusionresistances (ra+rl), and corresponding maximum CO2-exchangerates.  相似文献   

6.
In this study, we examined the hypothesis that stretch-induced (nitric oxide) NO modulates the mechanical properties of skeletal muscles by increasing accumulation of protein levels of talin and vinculin and by inhibiting calpain-induced proteolysis, thereby stabilizing the focal contacts and the cytoskeleton. Differentiating C2C12 myotubes were subjected to a single 10% step stretch for 0–4 days. The apparent elastic modulus of the cells, Eapp, was subsequently determined by atomic force microscopy. Static stretch led to significant increases (P < 0.01) in Eapp beginning at 2 days. These increases were correlated with increases in NO activity and neuronal NO synthase (nNOS) protein expression. Expression of talin was upregulated throughout, whereas expression of vinculin was significantly increased only on days 3 and 4. Addition of the NO donor L-arginine onto stretched cells further enhanced Eapp, NOS activity, and nNOS expression, whereas the presence of the NO inhibitor N-nitro-L-arginine methyl ester (L-NAME) reversed the effects of mechanical stimulation and of L-arginine. Overall, viscous dissipation, as determined by the value of hysteresis, was not significantly altered. For assessment of the role of vinculin and talin stability, cells treated with L-NAME showed a significant decrease in Eapp, whereas addition of a calpain inhibitor abolished the effect. Thus our results show that NO inhibition of calpain-initiated cleavage of cytoskeleton proteins was correlated with the changes in Eapp. Together, our data suggest that NO modulates the mechanical behavior of skeletal muscle cells through the combined action of increased talin and vinculin levels and a decrease in calpain-mediated talin proteolysis. mechanical stimulation; apparent elastic modulus; skeletal muscle cells; nitric oxide; stretch  相似文献   

7.
A simple technique is described for using a sulfide sensitiveelectrode to measure the photooxidation of H2S by a green sulfurbacterium, Chlorobium limicola forma thiosulfatophilum. Sulfidephotooxidation occurred only in the presence of bicarbonateat concentrations greater than 0.1 mM. This implies that therate-limiting carboxylating enzyme for CO2 fixation in Chlorobiumhas a relatively low affinity for CO2 compared to ribulose-1,5-biphosphatecarboxylase. Carbonyl cyanide-p-trifluoromethoxyphenyl-hydrazone(FCCP), an uncoupler of photophosphorylation, delays sulfideoxidation for about 15 sec after the onset of illumination at2 µM and is completely inhibitory at 10 µM. Theseeffects can be explained by the ATP requirement for CO2 fixation.When the photooxidation of H2S was prevented by 10 µMFCCP, a photoevolution of H2S was observed. (Received December 24, 1981; Accepted September 10, 1982)  相似文献   

8.
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 6–7 for nodulation and optimum temperature of 30–35°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   

9.
In a fern, Pteris vittata, inhibition by low-energy blue lightof phytochrome-dependent spore germination was counteractedby anerobiosis and respiratory inhibitors, such as KCN and NaN3.A 50% inhibition of spore germination in a medium containing0.3 mM NaN3 required about 8 times longer duration of blue lightirradiation compared with the control. The counteracting effectof NaN3 continued for about 32 hr after withdrawal of the inhibitor.However, NaN3 neither induced dark germination nor counteractedthe far-red light inhibition of spore germination. Reducingagents and uncouplers were tested and dithionite and arsenateslightly reversed the blue light inhibition of spore germination. (Received December 17, 1981; Accepted July 8, 1982)  相似文献   

10.
There are conflicting reports with regard to difference in effectsof day temperature (TD) and night temperatures (TN) on plantdevelopment. The objective of this study is to determine whetherthere are different effects ofTDandTNon development from sowingto flowering in rice (Oryza sativaL.). Plants of 24 rice cultivars were grown in naturally-lightedgrowth chambers at five diurnally constant (22, 24, 26, 28 and32 °C) and four diurnally fluctuating temperatures (26 /22,30 /22, 22 /26 and 22 /30 °C forTD/TNwith 12hd-1each) witha constant photoperiod of 12hd-1. The treatments were selectedto enable the separation of effects ofTDandTNon developmentrate (DR). The response of DR to constant temperatures was typically nonlinear.This nonlinearity could not explain the difference in floweringdates between fluctuating temperatures with the same mean dailyvalue but oppositeTD/TNdifferences. Differential effects ofTDandTNonDR to flowering were detected in all but one cultivar. In mostcases,TDexerted a greater influence thanTN, in contrast withmany previous reports based on the assumption of a linearitybetween DR and temperature. The data were further analysed bya nonlinear model which separated effects ofTDandTN. The estimatedvalue for the optimumTNwas generally 25 –29 °C, about2 –4 °C lower than the estimated optimumTDin mostcultivars. The effects ofTDandTNon DR were found to be interactivein some cultivars. These results form a new basis for modellingflowering dates in rice. Oryza sativa; rice; flowering; development; day and night temperature; thermoperiodicity  相似文献   

11.
邱明生  赵志模 《昆虫学报》1999,42(2):145-149
研究了环境因子对角倍蚜Schlechtendalia chinensis (Bell) 秋迁蚜生殖和雌性蚜发育的影响。温、湿度单因子试验表明,秋迁蚜在26℃和80%RH条件下有最大生殖量;温、湿度对秋迁蚜生殖量的影响均符合开口向下的二次抛物线变化趋势,极端温、湿度会导致生殖量的下降。采用三元一次正交组合设计,研究了环境温度(X1)、湿度(X2)和光照强度(X3)三因子不同水平组合对雌性蚜发育的影响,表明温度是影响发育历期的主要因子,其次是光照强度,最后是湿度。因此,适当高温、强光照条件可以加快雌性蚜发育;而适当高湿条件可以降低雌性蚜的发育速率而延长其发育历期。在人工培育角倍蚜生产中,创造有利于秋迁蚜生殖的温、湿度条件可以使秋迁蚜产下较多的越冬侨蚜;在适当降低温度、增加湿度的阴暗条件下贮留雌性蚜可以适当延长其发育,以使角倍蚜与盐肤木在物候上达到最佳吻合。  相似文献   

12.
Some Properties of the Arginine Decarboxylase in Vicia faba Leaves   总被引:1,自引:0,他引:1  
Growth of Vicia faba seedlings is accompanied by a rapid increasein arginine decarboxylase (EC 4.1.1.19 [EC] ) in the leaves and epicotyl.Increased enzyme activity was observed under saline conditionsin the presence of NaCl and with osmotic stress by mannitol.The partially purified enzyme (about 86-fold) readily decarboxylatedL-arginine, while D-arginine, L-homoarginine, L-ornithine andL-lysine were decarboxylated very slowly, and L-citrulline andL-glutamic acid were not decarboxylated. The Km value was 5.8?10–4M for L-arginine. The optimal pH and temperature for activitywere 8.5 and 45?C, respectively. p-Chloromercuribenzoate andN-ethylmaleimide were effective inhibitors of the enzyme. Inhibitionby spermidine, putrescine and agmatine suggested a possiblefeed-back mechanism in the pathway of polyamine biosynthesis. (Received October 11, 1983; Accepted February 24, 1984)  相似文献   

13.
Photochemical properties were determined for undegraded phytochromepurified from lyophilized rye seedlings (Secale cereale cv.Cougar). The preparation was shown to be a two-component systemduring phototransformations and dark transformation from red-light-inducedphotostationary state. The mole fraction of PFR at the 665-nm-light-inducedphotostationary state was 0.84. The ratio of the quantum yieldof photoconversion from PR to PFR to that from PFR to PR was1.53. 1 Present address: Division of Biological Regulation, NationalInstitute for Basic Biology, Myodaijicho, Okazaki 444, Japan (Received March 18, 1981; Accepted August 3, 1981)  相似文献   

14.
Seeni  S.; Gnanam  A. 《Plant & cell physiology》1981,22(6):1131-1135
Chlorophyll synthesis in the regreening photoheterotrophic calluscultures of Arachis hypogaea and Kalanchoe fedtschenkoi wassaturated at a light intensity of 5,000 lux. However, the optimaldevelopment of photosynthetic functions (O2 evolution, CO2 fixation,photosystem activities) required more irradiance (12,000–14,000lux). It was concluded that chlorophyll is not a useful indexof the photosynthetic potential in such cells. (Received January 23, 1981; Accepted July 10, 1981)  相似文献   

15.
A photoactive reaction center (RC) complex was isolated fromthe green sulfur bacterium Chlorobium tepidum by solubilizationof membranes with Triton X-100, followed by sucrosedensity gradientcentrifugation, DEAE Bio-Gel A chromatography, and hydroxyapatitechromatography. The purified RC complex contained about 50–70bacteriochlorophyll molecules (BChl) per P840, as assayed byphotooxidafion. It showed a near-infrared BChl a absorptionpeak at 814 nm and shoulders at about 800 and 835 nm at roomtemperature. SDS-PAGE analysis revealed 6 polypeptides withapparent molecular masses of 100, 65, 41, 32, 23, and 18 kDa.The RC complex binds functional P840 and Cyt c551, which werephotooxidized by continuous illumination at room temperature.Upon flash excitation, the bound Cyt c551 was oxidized, andrereduced in the dark with a half-time of 16 and 400 ms in thepresence and absence of 0.1 mM 2,6-dichlorophenol indophenol,respectively, at room temperature. At 551 nm, the amount ofthe Cyt c photooxidized by continuous illumination was 60% ofthe amount determined by chemical oxidation-reduction. The functionalCyt c551/P840 ratio was calculated to be 1.2–1.7. EPRspectroscopy at cryogenic temperatures revealed that the RCcomplex binds three photoreducible Fe-S centers designated tobe CFA, CFB and CFX (C for Chlorobium). CFA and CFB were reducedin the dark with dithionite at pH 10. (Received May 26, 1993; Accepted October 4, 1993)  相似文献   

16.
Dark CO2 fixation by Anabaena cylindrica was stimulated aboutthree-fold by the addition of NH4Cl to the cells. The 14CO2incorporation experiments showed that 14C is most rapidly incorporatedinto aspartate and then glutamine by adding NH4CI. Glutamineaccumulated predominantly after the addition of NH4Cl showingthat NH4 is incorporated into glutamine by glutamine synthetase.The stimulating effect of NH4Cl on CO2 fixation and amino acidsynthesis was suppressed by methionine sulfoximine, an inhibitorof glutamine synthetase. It was suggested that dark CO2 fixationwas stimulated by the action of glutamine synthesis which isenhanced by ammonia. (Received February 10, 1981; Accepted April 2, 1981)  相似文献   

17.
Mesophyll resistance to photosynthetic carboxylation (r'm) wasused as a criterion for leaf integrity. It was measured, at25 °C, in the light, before and after periods of high temperature(3 h at 38 °C) in the dark. During the high temperatureperiods, respiration (RD) of attached leaves of Xanthium strumariumwas suppressed from 27%-36% by either low [O2] (1.04% or 0.21%v.v.) or high [CO2] (840 µl 1–1) in the ambientair. Neither treatment affected rates of RD or photo-respirationduring the second period at 25 °C. There was no significant increase of r'm when RD was not suppressedduring the high temperature treatment. When RD was suppressedat high temperatures, r'm increased from about 3s cm–1before, to about 26 s cm–1 after the high temperaturetreatment. The increase depended upon the degree of suppression. It is concluded that increased RD at high temperature in Xanthiumleaves is partly the result of an increase of energy demandingmaintenance. The subsequent rate of carbon dioxide fixationis reduced when this increase of maintenance-induced respirationis inhibited.  相似文献   

18.
A low-temperature sensitive strain, Chlorella ellipsoidea Gerneck(IAM C-102), lost its chilling sensitivity during preservation.Cells of the original strain (low-temperature sensitive) andthe variant (low-temperature resistant) were both synchronouslygrown under a 14-hr light-10-hr dark regime. In the originalstrain, cells at the D-L stage (transient phase) were most sensitiveto a low temperature, whereas the variant cells were not damagedat any stage. During low-temperature treatment, the viability of D-L cellsin the sensitive strain decreased after a lag period of 1 hr.The O2-uptake activity (respiration) showed the same behavioras the viability, whereas the O2-evolution activity (photosynthesis)decreased from the start of chilling. In the resistant strain,only O2 evolution decreased. The decreased activity was restoredwhen the chilled cells were incubated at 25°C. This restorationwas inhibited by oligomycin. Lowering the light intensity or eliminating O2 diminished thechilling injury of the sensitive strain. The results indicatethat the chilling injury of Chlorella results from the combinedeffects of low temperature, light and O2. (Received September 26, 1980; Accepted March 23, 1981)  相似文献   

19.
The relative requirement of N and P (the optimum N:P ratio)by Dunaliella tertiolecta, Phaeodactylum tricornutum, Prymnesiumparvum and Thalassiosira pseudonana was studied under variouslight intensities and spectra. The ratio was determined as theratio of the minimum cell N and P concentrations (q0N and q0pwhen either nutrient was limiting. The ratio varied widely amongspecies; under light-saturation for growth (116 µEin m–2s–1 it ranged from 11.8 in D. tertiolecta to 36.6 in P.tricornutum. The ratio appeared to be higher at a sub-saturatingintensity (24 µEin m–2 s–1 in all except P.tricornutum, mainly because of higher qoN with little changein qoP. In T. pseudonana QoP also increased, resulting in aninsignificant change in the ratio. The ratio varied little withinthe range of saturation intensity. Light quality affected qoNand qoP as well as the ratio, and the pattern of change variedfrom species to species. The optimum ratio of individual specieswas linearly correlated to their qoN except in P. tricornutum.qoN for all species showed a linear correlation with cell proteinconcentrations irrespective of light conditions. The changeof optimum N:P ratios in the three species thus appears to berelated to changes in cell protein contents. The ratio of carbohydratesto protein remained constant regardless of light intensity orquality and was higher in P-limited cultures. We conclude thatchanges in light regime can strongly influence algal nutrientrequirements and species interrelationships by altering theoptimum cellular N:P ratio.  相似文献   

20.
Positive linear relationships were shown between constant temperaturesand the rates of progress of germination to different percentiles,G, for single populations of each of five genotypes of chickpea(Cicer anetinum L.). The base temperature, Tb, at which therate of germination is zero, was 0·0°C for all germinationpercentiles of all genotypes. The optimum temperature, To(G),at which rate of germination is most rapid, varied between thefive genotypes and also between percentiles within at leastone population. Over the sub-optimal temperature range, i.e.from Tb to To(G), the distribution of thermal times within eachpopulation was normal. Consequently a single equation was appliedto describe the influence of sub-optimal temperatures on rateof germination of all seeds within each population of each genotype.The precision with which optimum temperature, Tb(G), could bedefined varied between populations. In each of three genotypesthere was a negative linear relationship between temperatureabove Tb(G) and rate of germination. For all seeds within anyof these three populations thermal time at supra-optimal temperatureswas constant. Variation in the time taken to germinate at supra-optimaltemperatures was a consequence of normal variation in the ceilingtemperature, To(G)—the temperature at or above which rateof progress to germination percentile G is zero. A new approachto defining the response of seed germination rate to temperatureis proposed for use in germplasm screening programmes. In two populations final percentage germination was influencedby temperature. The optimum constant temperature for maximumfinal germination was between 10°C and 15°C in thesepopulations; approximately 15°C cooler than the optimumtemperature for rate of germination. It is suggested that laboratorytests of chickpea germination should be carried out at temperaturesbetween 10°C and 15°C. Key words: Chickpea, seed germination rate, temperature  相似文献   

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