Extracellular ATP Promotes Stomatal Opening
Molecular Plant ? Volume 5 ? Number 4 ? Pages 852–864 ? July 2012RESEARCH ARTICLE Extracellular ATP Promotes Stomatal Opening
of Arabidopsis thaliana through Heterotrimeric G Protein a Subunit and Reactive Oxygen Species Li-Hua Hao a,2,Wei-Xia Wang a,2,Chen Chen a,2,Yu-Fang Wang a,Ting Liu a,Xia Li b and Zhong-Lin Shang a,1
a Key Laboratory of Molecular and Cell Biology of Hebei Province,College of Life Sciences,Hebei Normal University,Shijiazhuang050016,P.R.China
b State Key Laboratory of Plant Cell and Chromosome Engineering,Center of Agricultural Resources Research,Institute of Genetics and Developmental Biology,Chinese Academy of Sciences,Shijiazhuang050021,P.R.China
ABSTRACT In recent years,adenosine tri-phosphate(ATP)has been reported to exist in apoplasts of plant cells as a signal molecule.Extracellular ATP(eATP)plays important roles in plant growth,development,and stress tolerance.Here,extra-cellular ATP was found to promote stomatal opening of Arabidopsis thaliana in light and darkness.ADP,GTP,and weakly hydrolyzable ATP analogs(ATP g S,Bz-ATP,and2meATP)showed similar effects,whereas AMP and adenosine did not affect stomatal movement.Apyrase inhibited stomatal opening.ATP-promoted stomatal opening was blocked by an NADPH oxidase inhibitor(diphenylene iodonium)or deoxidizer(dithiothreitol),and was impaired in null mutant of NADPH ox-idase(atrbohD/F).Added ATP triggered ROS generation in guard cells via NADPH oxidase.ATP also induced Ca21in?ux and H1ef?ux in guard cells.In atrbohD/F,ATP-induced ion?ux was strongly suppressed.In null mutants of the heterotrimeric G protein a subunit,ATP-promoted stomatal opening,cytoplasmic ROS generation,Ca21in?ux,and H1ef?ux were all sup-pressed.These results indicated that eATP-promoted stomatal opening possibly involves the heterotrimeric G protein, ROS,cytosolic Ca21,and plasma membrane H1-ATPase.
Key words:Extracellular ATP;stomatal movement;Arabidopsis thaliana;heterotrimeric G protein;reactive oxygen species.
INTRODUCTION
Adenosine5’-triphosphate(ATP)was regarded as an intracel-lular energy molecule for many years.However,ATP has been detected in extracellular spaces during the past30–40years.In mammalian cells,extracellular ATP(so-called eATP)is involved in neurotransmission,cell growth,and programmed cell death (Burnstock and Verkhratsky,2009).Thus,ATP is regarded as an important extracellular signal molecule that modulates vari-ous metabolic functions.
ATP is also found in extracellular spaces of plant cells.Dur-ing the past decade,the existence,physiological function, and signal transduction of eATP in plant cells has been revealed(see review by Roux and Steinebrunner,2007; Tanaka et al.,2010a).Exogenous ATP exerts various physio-logical effects,including promoting growth and develop-ment(Lew and Dearnaley,2000;Wolf et al.,2007;Clark et al.,2010;Tono′n et al.,2010),inducing stress resistance (Jeter et al.,2004;Song et al.,2006;Wu et al.,2008;Chivasa et al.,2009),inhibiting pollen germination(Steinebrunner et al.,2003;Roux and Steinebrunner,2007;Reichler et al., 2009),and disturbing root gravitropism(Tang et al.,2003).
The role of ectoapyrase in the regulation of metabolism in-
directly indicates endogenous eATP exists in the cell wall and
plays roles in maintaining cell viability(Chivasa et al.,2005),reg-
ulating cell growth and development,and inducing defense responses(Steinebrunner et al.,2003;Wolf et al.,2007;Wu
et al.,2007a;Riewe et al.,2008a,2008b;Clark et al.,2010).
The existence and dynamic variation of eATP levels have been demonstrated,con?rming the close relationship between eATP
and its physiological functions(Kim et al.,2006).
The signal transduction mechanism of eATP has been inves-
tigated using various techniques.Indirect evidence from
1To whom correspondence should be addressed at College of Life Sciences,
Hebei Normal University,Yuhua East Road113,Shijiazhuang,Hebei050016,
P.R.China.E-mail shangzhonglin@https://www.wendangku.net/doc/897859299.html,,tel.+86-311-86269814,
fax+86-311-86268313.
2These authors contributed equally to this work.
aThe Author2011.Published by the Molecular Plant Shanghai Editorial
Of?ce in association with Oxford University Press on behalf of CSPB and
IPPE,SIBS,CAS.
doi:10.1093/mp/ssr095
Received3August2011;accepted29October2011
at Yangzhou University on October 1, 2013
https://www.wendangku.net/doc/897859299.html,/
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pharmacological experiments indicated that purinergic recep-tors might exist in plant cells(Demidchik et al.,2003a;Chivasa et al.,2005;Song et al.,2006).The components of the eATP signaling pathway in mammalian cells,including reactive ox-ygen species(ROS),NO,and Ca2+,also act in eATP-regulated physiological functions in plant cells.NADPH oxidase-cata-lyzed ROS generation is involved in eATP signal transduction (Kim et al.,2006;Song et al.,2006;Wu et al.,2008;Demidchik et al.,2009).Cytosolic Ca2+is involved in eATP-regulated phys-iological reactions(Demidchik et al.,2003a;Jeter et al.,2004; Wu et al.,2008;Demidchik et al.,2009;Shang et al.,2009; Tanaka et al.,2010b).ATP also triggers NO generation(Foresi et al.,2007;Torres et al.,2008;Wu and Wu,2008;Reichler et al.,2009;Sueldo et al.,2010;Tono′n et al.,2010).Down-stream physiological reactions of eATP-induced Ca2+signaling, including gene expression(Song et al.,2006;Kim et al.,2009b) and synthesis of speci?c proteins(Chivasa et al.,2010),were also reported.
Stomata are important gates that are responsible for water transpiration and gas exchange.To clarify the mechanism of sto-matal movement,signal transduction in guard cells has been in-vestigated in detail.Stimuli might exert their effect on stomatal movement by activating receptors in the plasma membrane (PM)or cytoplasm,and then modulate cytoplasmic metabolism directly or indirectly through generation of a secondary messen-ger(see review by Assmann,1993;Schroeder et al.,2001;Pandey et al.,2007;Shimazaki et al.,2007).A heterotrimeric G protein in the PM is involved in stomatal movement(Wang et al.,2001; Chen et al.,2004;Pandey and Assmann,2004;Zhang et al., 2008).Phytochrome B has been found to be involved in red-light-induced stomatal opening(Wang et al.,2010).Intracellu-lar secondary messengers,such as Ca2+(McAinsh et al.,1990; Kinoshita et al.,1995;Pandey et al.,2007),ROS,and NO(Pei et al.,2000;Neill et al.,2002;Desikan et al.,2004),are also in-volved in stimuli-induced stomatal movement.Members of SNAREs,a superfamily of membrane traf?cking proteins,were reported to be involved in stomatal movement via regulating calcium channel activities(Sokolovski et al.,2008).Blue light and auxin-induced stomatal opening is driven by a proton pump in the PM of guard cells(Assmann et al.,1985;Shimazaki et al.,1986;Kinoshita and Shimazaki,1999;Ueno et al.,2005; Merlot et al.,2007),which leads to membrane hyperpolariza-tion and ion channel activation(Dietrich et al.,2001;Harada and Shimazaki,2009).Abscisic acid(ABA)-induced stomatal clos-ing and ABA-inhibited stomatal opening partially results from in-activation of the PM H+-ATPase(Brault et al.,2004;Zhang et al., 2004).These results indicate that the PM H+-ATPase responds to various stimuli as a key stomatal movement regulator.
Raghavendra(1981)and Nejidat et al.(1983)reported that added ATP remarkably promotes stomatal opening in Comme-lina benghalensis and Commelina communis,respectively.Nev-ertheless,ATP was regarded as an energy source in those experiments.Most recently,Clark et al.(2011)reported that ap-yrase and eATP participated in stomatal movement as signal mol-ecules.However,the mechanism of eATP-promoted stomatal opening is still unclear.Herein,we investigated the role of eATP in stomatal movement and the signaling pathway of eATP in guard cells of Arabidopsis thaliana.
RESULTS
Extracellular ATP Promotes Stomatal Opening in Arabidopsis thaliana as a Signal Molecule
To investigate the role of eATP in stomatal movement,epider-mal strips were placed in MES buffer containing ATP and then the stomatal aperture at different time points was measured. When exposed to light,the stomatal aperture increased with time.In ATP-treated epidermal strips,the stomatal aperture at each time point was bigger than that in the control(n=6,P, 0.05)(Figure1A).The stomatal aperture at60min in re-sponse to0.1,0.3,0.5,and1.0mM ATP treatment increased gradually,showing that ATP promotes stomatal opening in a dose-dependent manner(Figure1B).
To exclude the possibility that ATP promotes stomatal opening as an energy carrier,non-or weakly hydrolyzabe ATP analogs were used to investigate their effect on stomatal move-ment.Three ATP analogs(0.3mM),ATP c S(Adenosine5’-O-(3-thio)triphosphate),2meATP(2-methylthio-adenosine 5’-triphosphate),and Bz-ATP(3’-O-(4-benzoyl)benzoyl aden-osine5’-triphosphate),all promoted stomatal opening similarly to ATP(Figure1C).
To verify the effect of other nucleotide phosphates on sto-matal opening,the effects of0.3mM ADP,AMP,adenosine, and GTP on stomatal movement were investigated.ADP and GTP promoted stomatal opening signi?cantly:the stomatal aperture at60min was bigger than that in the control(P, 0.05).However,AMP and adenosine did not have any effect on stomatal opening(P.0.05)(Figure1D).
To investigate the effect of ATP on stomatal opening in dif-ferent genetic backgrounds of Arabidopsis thaliana,two dif-ferent ecotypes(col-0and ws)were used.After0.3mM ATP treatment,stomatal opening was promoted in both ecotypes (Figure1E).
To con?rm that ATP promotes stomatal opening indepen-dently from light,the effect of ATP and an ATP analog, 2meATP,on stomatal movement in the dark was investigated. In col-0,ATP or2meATP promoted opening of stomata in the dark.The stomatal aperture increased after0.3,1,and2mM ATP or2meATP treatment,and the stomatal aperture was sig-ni?cantly bigger than the control(P,0.05)(Figure1F).In ws, ATP or non-hydrolyzable ATP analogs also promoted stomatal opening in the dark(data not shown).
To verify the role of endogenous eATP in stomatal move-ment,the effect of added apyrase,an enzyme that can decom-pose ATP,on stomatal movement in light was investigated.In MES buffer containing10or30units mlà1apyrase,stomatal opening was signi?cantly inhibited.The stomatal aperture af-ter2,3,and4-h treatment was signi?cantly smaller than that in control(P,0.05).By contrast,heat-inactivated apyrase
(30units ml à1)did not affect stomatal opening (P .0.05).The inhibitory effect of added apyrase on stomatal opening in-creased with increasing apyrase concentration:30units ml à1apyrase showed stronger suppression on stomatal opening than 10units ml à1apyrase (Figure 2A).In another control,the same concentration of bovine serum albumin did not af-fect stomatal movement (data not shown).
Apyrase has been reported to reduce cell viability by exhausting extracellular ATP (Chivasa et al.,2005).To exclude the possibility that added apyrase led to stomatal closing by reducing the viability of guard cells,epidermis that had been
treated with apyrase for 4h was stained with FDA (?uorescein diacetate)to investigate cell viabilities.In epidermis to which FDA was not added,no ?uorescence was detected in guard cells,indicating that there was no auto-?uorescence in the guard cells.Bright green ?uorescence was observed in guard cells before and after 4-h apyrase treatment (Figure 2C).The ?uorescent intensity in the control and apyrase-treated guard cells was not signi?cantly different (n =30,P .0.05),indicat-ing that the viability of guard cells was not affected by apyrase treatment (Figure 2B).
Reactive Oxygen Species Participate in eATP-Promoted Stomatal Opening
To verify the mechanism of eATP-promoted stomatal open-ing,the role of reactive oxygen species was investigated.First,CuCl 2and ascorbic acid were added to the bath solution to generate hydroxyl radicals (OH á),according to Demidchik et al.(2003b).Low and high concentrations of CuCl 2+ascor-bic acid mixture exerted contrasting effects on stomatal movement.Treatment with 0.1mM CuCl 2and ascorbic acid enhanced stomatal opening,whereas a higher ROS concen-tration (0.5and 1mM CuCl 2+ascorbic acid mixture)led to stomatal closure (Figure 3A).
To investigate the role of ROS in ATP-promoted stomatal opening,the effect of diphenylene iodonium (DPI),an inhibitor of NADPH oxidase,and dithiothreitol (DTT),a reductant that can eliminate ROS,on ATP-promoted stomatal opening was investigated.Pretreatment with 5l M DPI slightly inhibited sto-matal opening.In the presence of DPI,ATP-promoted stomatal opening was signi?cantly inhibited (P ,0.05)(Figure 3B).Pre-treatment with 100l M DTT also strongly suppressed ATP-promoted stomatal opening (P ,0.05)(Figure 3C).
To con?rm ROS participation in ATP-promoted stomatal opening,atrbohD/F ,a double-null mutant of the NADPH oxi-dase D and F subunits,was used as the plant material to inves-tigate the effect of added ATP on stomatal movement.The stomatal aperture was a little smaller in the mutant than that in the wild-type before ATP treatment.In atrbohD/F ,the sto-matal aperture before and after 0.3-mM ATP treatment was not signi?cantly different (P .0.05)(Figure 3D).
To con?rm the role of ROS in eATP-promoted stomatal opening,intracellular ROS levels were measured using H 2CDFDA,a ?uorescent indicator of ROS.ATP triggered an in-crease in ROS concentration in guard cells of the wild-type (col-0).However,in atrbohD/F ,this ATP-induced ROS increase was impaired (Figure 4).To exclude the possibility that ROS gener-ation was induced by hydrolyzed ATP products,the effect of 0.3mM 2meATP on ROS generation was investigated.The re-sult showed that 0.3mM 2meATP also stimulated ROS gener-ation in guard cells of col-0(data not shown).
The Heterotrimeric G Protein Participates in eATP-Promoted Stomatal Opening
To verify whether the heterotrimeric G protein participated in eATP-promoted stomatal opening,the effect of ATP
on
Figure 1.ATP-Promoted Stomatal Opening of Arabidopsis thali-ana .
(A)Time course of stomatal opening in MES buffer containing ATP .(B)Dose-dependence of ATP-promoted stomatal opening.
(C)Non-or weakly hydrolyzable ATP analogs promoted stomatal opening.
(D)The effect of various purine nucleotides on stomatal movement.(E)Added ATP promoted stomatal opening in two A.thaliana ecotypes.
(F)Added ATP or non-hydrolyzable ATP analog (2meATP)promoted stomatal opening in the dark.Stomatal apertures after 60-min treat-ment were noted.In (A),(C),(D),and (E),the ?nal concentration of added reagents was 0.3mM.In all ?gures,data are represented as means 6SE stomatal aperture (n =6).In all ?gures,‘control’means treatment with MES buffer only.In (B–E),the stomatal aperture was measured after 60-min treatment.In (A–D)and (F),ecotype col-0was used as the material.In all ?gures,ATP or ATP analogs promoted sto-matal opening predominantly (P ,0.05,Student’s t -test).
stomatal movement in two lost-of-function mutants of the G a subunit (gpa1-1and gpa1-2)was investigated.The result showed that ATP-promoted stomatal opening,which was detected in the wild-type (ws ),was impaired in both of the mutants.In the two mutants,the stomatal aperture before and after 60-min ATP treatment was not different (P .0.05)(Figure 5A).In darkness,0.3mM ATP or 2meATP promoted sto-matal opening in ws (P ,0.05).However,in the two mutants,stomatal aperture was similar before and after ATP treatment in the dark (P .0.05)(Figure 5B).
To verify the relation between the heterotrimeric G protein and ROS generation in ATP-promoted stomatal opening,the intracellular ROS concentration in guard cells of wild-type (ws )and G a null mutants was measured.In ws guard cells,0.3mM ATP evoked signi?cant ROS elevation (P ,0.05),whereas,in guard cells of gpa1-1and gpa1-2,the cytoplasmic ROS concentration was not affected by ATP treatment (P .0.05)(Figure 4).
ATP Triggers Ca 2+In?ux and H +Ef?ux in Guard Cells of Arabidopsis thaliana
To verify whether Ca 2+participates in eATP signaling in guard cells,the effect of 50l M gadolinium chloride (GdCl 3),a blocker of the voltage-dependent Ca 2+channel in the plasma mem-brane,on ATP-promoted stomatal opening was investigated.In epidermises pretreated with GdCl 3,the stomatal aperture was a little smaller than that in the control.At the same time,ATP-promoted stomatal opening was remarkably inhibited (Figure 6A).
To con?rm that Ca 2+is involved in eATP signaling in guard cells,Ca 2+?ux in guard cells was measured using a non-invasive micro-test (NMT)technique.To exclude the possibility that added reagents affected Ca 2+concentration alone,which would lead to false positive results,MES buffer,AMP ,or ATP was added into bath solution without epidermal strips and then Ca 2+?ux velocity before and after treatment was measured,re-spectively.The results showed that 0.6mM ATP did not
affect
Figure 2.Added Apyrase Inhibited Stomatal Opening of Arabidopsis thaliana .
Col-0was used as the material,and stomatal movement in light was investigated.
(A)Time course of stomatal movement in MES buffer containing apyrase.Data are means 6SE stomatal aperture (n =6)at different time points.The stomatal aperture was smaller in apyrase-treated epidermis (P ,0.05,Student’s t -test.).Heat-inactivated apyrase (30units ml à1)did not affect stomatal movement (P .0.05,Student’s t -test).
(B,C)Cell viability measurement after apyrase treatment.FDA was loaded into guard cells,and images were captured with confocal laser scanning microscope.Mean 6SE relative ?uorescent intensity in guard cells,which were treated by 10or 30units ml à1apyrase for 4h,was noted in (B).Images of representative guard cells that were treated with active or denatured apyrase are shown in (C).In all ?gures,‘con-trol’means treatment with MES buffer only.
Ca 2+?ux signi?cantly (Figure 6B).MES buffer or 0.6mM AMP also did not affect Ca 2+?ux signi?cantly (data not shown).In a bath solution containing epidermises of col-0,Ca 2+?ux velocity ?uctuated within a narrow range.When ATP was added into the bath solution,Ca 2+in?ux velocity began to in-crease after 1–2min,reached a peak value in about 1min,and then recovered to the basal level during the following 3–4min (Figure 6C).The peak Ca 2+in?ux velocity evoked by 0.1,0.3,and 0.6mM ATP gradually increased (Figure 6D).
To verify the role of PM H +-ATPase in eATP-promoted stoma-tal opening,the effect of Na 3VO 4,an inhibitor of plasma mem-brane H +-ATPase,on ATP-promoted stomatal opening was investigated.In epidermises of col-0,100l M Na 3VO 4pretreat-ment inhibited stomatal opening in light,and the stomatal ap-erture was smaller than that of the control.When 0.3mM ATP was added,stomatal opening was not promoted in Na 3VO 4-pretreated epidermal strips (Figure 6E).
To con?rm the role of H +-ATPase in eATP signaling,the ef-fect of ATP on H +ef?ux in guard cells was investigated using NMT.As a control,MES buffer,AMP ,or ATP was added into a bath solution without epidermal strips,respectively.The results showed that 0.6mM ATP did not affect H +?ux signif-icantly (Figure 6F).MES buffer or 0.6mM AMP also did
not
Figure 3.Reactive Oxygen Species (ROS)Participate in Extracellular ATP-Promoted Stomatal Opening in Arabidopsis thaliana (col-0).(A)Added ascorbic acid +CuCl 2mixture had contrasting effects on stomatal movement.Low-and high-concentration hydroxyl pro-moted stomatal opening and stomatal closing,respectively.
(B)Diphenylene iodonium (DPI)inhibited ATP-promoted stomatal opening.
(C)Dithiothreitol (DTT)inhibited ATP-promoted stomatal opening.(D)In an NADPH oxidase null mutant (atrbohD /F ),ATP-promoted stomatal opening was blocked.In all ?gures,the data are means 6SE (n =6)stomatal aperture after 60-min treatment with 0.3mM ATP.In col-0,which was pretreated by DPI (B)or DTT (C)and in atrbohD/F (D),the stomatal aperture before and after ATP treatment was not signi?cantly different (P .0.05,Stu-dent’s t -test).In all ?gures,‘control’means treatment with MES buffer
only.
Figure 4.The Heterotrimeric G Protein and NADPH Oxidase Are In-volved in ATP-Promoted Cytoplasmic Reactive Oxygen Species (ROS)Generation in Guard Cells.
Cytoplasmic ROS in guard cells was stained with H 2CDFDA.
(A)Fluorescence was captured using a laser confocal scanning mi-croscope and is shown as pseudocolor images.The pseudocolor bar is shown at the bottom of (A).Fluorescent images before (control)and after 0.3mM ATP treatment for 120s (ATP),and the corre-sponding bright?eld images,are shown.The scale bar is shown on the left bottom of (A).
(B)Means 6SE of relative ?uorescent intensities in 30guard cells.In the two wild-types,ATP markedly stimulated ROS generation (P ,0.05,Student’s t -test).In null mutants of G a or NADPH oxidase,?uo-rescent intensity was not remarkably different before and after ATP treatment (P .0.05,Student’s t -test).In all ?gures,‘control’means treatment with MES buffer only.
affect H +?ux signi?cantly (data not shown).The resting H +?ux velocity in guard cells ?uctuated over a certain range.Af-ter ATP stimulation for 2–3min,H +ef?ux velocity increased,reached a peak value in about 1min,and then recovered to the basal level in the following 3–4min (Figure 6G).The peak H +ef?ux velocity evoked by 0.1,0.3,and 0.6mM ATP gradually increased (Figure 6H).
To con?rm that ATP hydrolysis is not necessary for triggering ion ?ux,the effect of 0.6mM 2meATP on ion ?ux was investi-gated.The result showed that 2meATP stimulated ion ?ux (both Ca 2+in?ux and H +ef?ux)similarly to ATP (data not shown).
The Heterotrimeric G Protein and ROS Participate in eATP-Evoked Ca 2+In?ux and H +Ef?ux in Guard Cells of Arabidopsis thaliana
To verify the mechanism of ATP-stimulated Ca 2+in?ux and H +ef?ux in guard cells,null mutants of G a and NADPH oxidase were used as plant materials to investigate the effect of 0.6mM ATP on Ca 2+in?ux and H +ef?ux,respectively.In gpa1-1and gpa1-2,ATP did not promote Ca 2+in?ux (Figure 7A).The peak Ca 2+in?ux velocity in gpa1-1and gpa1-2was far lower than that in the wild-type (P ,0.05)(Figure 7B).Com-pared to the remarkable Ca 2+in?ux in col-0,0.6mM ATP only evoked weak Ca 2+in?ux in atrbohD/F (Figure 7C).In response to 0.6mM ATP treatment,the peak Ca 2+in?ux velocity in atr-bohD/F was signi?cantly lower than that in the wild-type (P ,0.05)(Figure 7D).
To verify the role of the heterotrimeric G protein and ROS in ATP-stimulated H +ef?ux,the effect of ATP on H +ef?ux in gpa1-1,gpa1-2,and atrbohD/F was investigated.The ATP-stimulated H +ef?ux recorded in the corresponding wild-type was not observed in the two mutants.The H +ef?ux velocity only slightly increased after 0.6mM ATP treatment in gpa1-1and atrbohD/F (Figure 7E and 7G).The peak H +ef?ux velocity before and after ATP treat-ment further con?rmed that loss-of-function of G a or NADPH ox-idase caused a lack of response to ATP (Figure 7F and 7H).
DISCUSSION
Extracellular ATP Participates in Stomatal Opening in Arabidopsis thaliana as a Signal Molecule
In this study,we provided three ?ndings that support the hy-pothesis that ATP promotes stomatal opening as a signal mol-ecule:(1)a low concentration of added ATP promoted stomatal opening;(2)non-hydrolyzable ATP analogs promoted stomatal opening;and (3)ADP and GTP also promoted stomatal opening.ATP or non-hydrolyzable ATP analog (2meATP)promoted sto-matal opening in both the light and the dark,indicating that ATP promoted stomatal opening independently of light.
The cytoplasmic ATP concentration in plant cells is typically at the millimolar level (Gout et al.,1992),which is higher than the level we used in this work (mainly at 0.3mM).Thus,it is less likely that ATP penetrated the PM to overcome the ATP gradient and alter the cytoplasmic ATP concentration in the guard cells.The effect of non-hydrolyzable ATP analogs on stomatal opening further excluded the possibility that added ATP acted as a sup-plied energy charger.ADP and GTP are reported to have a similar effect to ATP ,while AMP and adenosine do not affect related physiological processes (as reviewed by Roux and Steinebrunner,2007;Tanaka et al.,2010a).In this work,ADP and GTP promoted stomatal opening,whereas AMP and adenosine did not affect this process.This result further con?rmed that eATP may act as a signal molecule to modulate stomatal movement.
Apyrase has been reported to decompose extracellular ATP and inhibit eATP-induced physiological reactions.Here,added apyrase led to inhibition of stomatal opening,indirectly indi-cating that endogenous eATP is necessary for maintaining reg-ular stomatal movement.Chivasa et al.(2005)reported that apyrase treatment may possibly lead to a decrease of cell via-bility in plants.Here,cell viability measurement excluded the possibility that added apyrase weakened guard cell viability,which may lead stomatal closure.
Based on the above results,we suggest that ATP plays a posi-tive role in stomatal opening in Arabidopsis thaliana as an extra-cellular signal molecule.Recently,Clark et al.(2011)reported that low concentrations of ATP (,30l M)promoted stomatal opening and highly concentrated ATP (.100l M)led to stomatal closure.However,ATP-induced stomatal closing was not observed in our experiments.In another experiment,using epidermis of Vicia faba as the plant material,we found that ATP promoted stomatal opening in a similar dose-dependent manner as observed in Ara-bidopsis .ATP-induced stomatal closure was also not observed in the Vicia faba guard cells (unpublished data).
Reactive Oxygen Species Participate in eATP-Stimulated Stomatal Opening
Reactive oxygen species are involved in eATP-regulated phys-iological functions (Kim et al.,2006;Song et al.,2006;Wu et al.,2008;Demidchik et al.,2009).Herein,the role of ROS in eATP-promoted stomatal opening was detected.
Three ?ndings revealed that ROS accumulation,catalyzed by NADPH oxidase,participated in eATP-promoted
stomatal
Figure 5.The Heterotrimeric G Protein Participates in Extracellular ATP-Promoted Stomatal Opening.
(A)and (B)show stomatal apertures of wild-type and G a null mutants before and after 60-min ATP or 2meATP treatment in light (A)and darkness (B),respectively.Data are means 6SE (n =6)for stomatal aperture.The concentration of ATP or 2meATP was 0.3mM.In gpa1-1and gpa1-2,stomatal apertures before and after treatment were not signi?cantly different (P .0.05,Student’s t -test).In all ?gures,‘control’means treatment with MES buffer only.
Figure6.ATP Stimulates Ca2+In?ux and H+Ef?ux in Guard Cells of Arabidopsis thaliana(Ecotype col-0).
(A)Gadolinium chloride(50l M)blocked ATP-promoted stomatal opening.
(B)and(C)show time course of Ca2+?ux in MES buffer without(B)or with(C)epidermis before and after0.6mM ATP treatment,respec-tively.The arrow marks time points of ATP treatment.
(D)The dose-dependence of ATP-promoted Ca2+in?ux;data are the means6SE(n=30)of the peak Ca2+in?ux value after ATP stimulation.
The positive and negative values of ion?ux represent ion in?ux and ef?ux,respectively.
opening:(1)bothDPIandDTTsuppressedeATP-promotedstoma-tal opening;(2)in atrbohD/F,eATP-promoted stomatal opening was impaired;and(3)eATP evoked elevation of the ROS concen-tration in guard cells,providing direct evidence of eATP-induced ROS generation.This generation was abolished in a double null mutant of NADPH oxidase,indicating that the ATP-induced ROS increase might result from activation of this enzyme.
Reactive oxygen species play a crucial role in stomatal movement,especially in stomatal closure induced by ABA, ethylene,and a fungal elicitor(Pei et al.,2000;Neill et al., 2002;Kwak et al.,2003;Desikan et al.,2004).Results in this work revealed that eATP-evoked ROS generation may regu-late stomatal movement in the opposite manner,namely by promoting stomatal opening.To con?rm that ROS is capable of stimulating stomatal opening,we investigated the effect of ROS on stomatal movement using a CuCl2+ascorbic acid mixture to generate hydroxyl radicals.The results showed that ROS has a double effect on stomatal movement:they promote stomatal opening at a low concentration and pro-mote stomatal closure at a high concentration.It is still dif-?cult to measure the absolute ROS concentration in plant cells;therefore,we cannot estimate whether the high con-centration of ROS used in our experiment(.0.5mM CuCl2+ ascorbic acid)is in the range that led to stomatal closure in other researchers’experiments.Nevertheless,we believe ROS impacts on stomatal opening in a positive manner,at least within a certain concentration range.Cytosolic Ca2+ is an example of signal components that play a con?icting role in regulating stomatal movement.Many stimuli evoke cytosolic Ca2+increase in guard cells.ABA-evoked Ca2+ele-vation leads to stomatal closure(McAinsh et al.,1990; Kinoshita et al.,1995),whereas IAA-induced Ca2+elevation led to stomatal opening(Irving et al.,1992;Curvetto et al., 1994;Cousson and Vavasseur,1998),although the temporal ([Ca2+]elevation and oscillation)and spatial features of the Ca2+signal appeared similar.The reason why the same signal induces opposing physiological reactions is still unclear.One possibility is the downstream targets of the signal are differ-ent;another is the cross-talk between different signals.For ROS and Ca2+signal,they have numerous targets,responding to different upstream stimuli and leading different down-stream reactions.Cross-talk between various signals will gen-erate various combinations.The encoding and decoding style of different signals will be totally different(Kim et al.,2009a; Mazars et al.,2010).The results of the present study probably provide another example of a signal molecule in guard cells responding to different stimuli and regulating con?icting physiological functions.The Heterotrimeric G Protein Participates in
eATP-Stimulated Stomatal Opening
In G a null mutants,eATP-promoted stomatal opening and ROS generation were both blocked,indicating that the heterotri-meric G protein may play an important role in eATP signaling by modulating ROS generation.A heterotrimeric G protein coupled receptor(GPCR)is one of the purinic receptors in the PM of mammalian cells(see review by Burnstock,2006; Burnstock and Verkhratsky,2009).The involvement of the het-erotrimeric G protein in eATP signaling in plant cells was reported recently.Weerasinghe et al.(2009)reported that the heterotrimeric G protein participated in ATP release in Ara-bidopsis roots.Tanaka et al.(2010b)reported that the hetero-trimeric G protein might be involved in extracellular nucleotide-elicited cytosolic Ca2+elevation and oscillation in Arabidopsis leaf and root cells.The results of the present study provide additional evidence for the role of the heterotrimeric G protein in eATP signal transduction.In recent years,the het-erotrimeric G protein and G-protein coupled receptor have been reported to participate in stomatal movement by regu-lating ion channels in the PM of guard cells(Wang et al.,2001; Chen et al.,2004;Pandey and Assmann,2004).The heterotri-meric G protein also participates in ROS metabolism in plant cells(Wei et al.,2008;Zhao et al.,2010).Here,we suggest that the heterotrimeric G protein might connect the eATP signal with NADPH oxidase as a signal transducer in guard cells.
The Heterotrimeric G Protein a Subunit and NADPH Oxidase Are Involved in eATP-Evoked Ion Flux
It was reported that eATP evoked cytosolic Ca2+elevation, generating a speci?c Ca2+signal and initiating downstream physiological processes,which ultimately modulate metabo-lism.The Ca2+in?ux might be the main source of the eATP-stimulated Ca2+signal(Demidchik et al.,2003a;Jeter et al., 2004;Wu et al.,2008;Demidchik et al.,2009;Shang et al., 2009;Tanaka et al.,2010b;Demidchik et al.,2011).The result that gadolinium blocked eATP-promoted stomatal opening in-dicated that Ca2+in?ux through Ca2+channels in the PM may play an important role in eATP signaling in guard cells.Hence, we investigated the role of Ca2+in?ux in eATP signal transduc-tion in guard cells using NMT.
Before we investigated the effect of the addition of ATP on ion?ux velocity,some control experiments were performed to con?rm that the method was valid for ion?ux measurement in epidermal strips.Added ATP did not affect ion?ux around the electrode in MES buffer without epidermis,indicating that sig-ni?cant ion?ux change was not a nonspeci?c effect,but a re-sult of ion in?ux or ef?ux in living cells.
(E)Sodium vanadate(100l M)blocked ATP-promoted stomatal opening.
(F)and(G)show time courses of H+?ux in MES buffer without(F)or with(G)epidermis before and after0.6mM ATP treatment,respectively. The arrow marks time points of ATP treatment.In(A)and(E),data are means6SE(n=6)for stomatal aperture.In all?gures,‘control’means treatment with MES buffer only.(H)The dose-dependence of ATP-promoted H+in?ux;data are the means6SE(n=30)of the peak H+ef?ux value after ATP stimulation.
Figure7.The Heterotrimeric G Protein and Reactive Oxygen Species Are Involved in ATP-Stimulated Ca2+In?ux and H+Ef?ux.
(A)and(C)show the time course of Ca2+in?ux before and after0.6mM ATP treatment in null mutants of heterotrimeric G protein a subunit
(A)and NADPH oxidase D/F subunit(C)and their wild-type epidermis,respectively.The arrow marks the time point of ATP treatment.
(B)and(D)show the means6SE(n=30)peak Ca2+in?ux velocity before and after ATP treatment in the wild-type and null mutants.
(E)and(G)show the time course of H+ef?ux before and after0.6mM ATP treatment in null mutants of heterotrimeric G protein a subunit(E) and NADPH oxidase D/F subunit(G)and their wild-type epidermis,respectively.The arrow marks the time point of ATP treatment. (F)and(H)show the means6SE(n=30)peak H+ef?ux velocities before and after ATP treatment in the wild-type and null mutants.In all
?gures,‘control’means treatment with MES buffer only.
Hao et al.?ATP Promotes Stomatal Opening of Arabidopsis thaliana861
Extracellular ATP evoked transient increase(Demidchik et al., 2003a)or oscillation of cytosolic Ca2+concentration([Ca2+]cyt) (Tanaka et al.,2010b)in Arabidopsis cells.In the present study, the temporal features of Ca2+in?ux re?ected transient eleva-tion and relatively slower recovery of[Ca2+]cyt in guard cells. As described above,cytosolic Ca2+is involved in stomatal move-ment,including ABA-or ethylene-induced stomatal closure and auxin-induced stomatal opening.Here,eATP promoted ion in-?ux,indicating that Ca2+is also involved in eATP-promoted sto-matal opening as an intracellular messenger.
The H+ef?ux generated by H+-ATPase is involved in stomatal opening.H+ef?ux results in a H+gradient across the PM and hyperpolarization of the membrane potential.This gradient is the main driving force for solute absorption,which will strongly promote water absorption and stomatal opening(Assmann et al.,1985;Kinoshita and Shimazaki,1999;Merlot et al., 2007;Harada and Shimazaki,2009).Here,sodium vanadate blocked eATP-promoted stomatal opening,indicating that H+-ATPase might be involved in eATP signaling.Results of H+ef?ux measurement further con?rmed this conclusion.H+-ATPase is the main H+ef?ux charger in the PM;therefore,the increased H+ef?ux re?ected activation of this enzyme.Our results dem-onstrated that H+-ATPase may be an important signal transduc-tion component in eATP-promoted stomatal opening.
In null mutants of G a or NADPH oxidase,eATP-stimulated Ca2+in?ux was not recorded,indicating that these signal trans-duction components might be involved in eATP-triggered Ca2+ signaling.Ca2+in?ux stimulated by ROS participates in ABA-and elicitor-induced stomatal closure(Murata et al.,2001;Kwak et al.,2003).The heterotrimeric G protein also modulates Ca2+channels in the PM of plant cells(Aharon et al.,1998; Wu et al.,2007b)and is involved in eATP-induced Ca2+oscillation in Arabidopsis seedlings(Tanaka et al.,2010b).The results in the present study further con?rmed that the heterotrimeric G pro-tein and ROS may act as important signal transducers in eATP signal transduction in guard cells.The heterotrimeric G protein a subunit and NADPH oxidase are also involved in modulating PM H+-ATPase in plant cells(see review by Gaxiola et al.,2007). Harada and Shimazaki(2009)reported that blue light induced both H+-ATPase activation and[Ca2+]elevation in Arabidopsis guard cells.
The results in the present study further demonstrated that the heterotrimeric G protein may also respond to extracellular ATP stimulation and connects the eATP signal with stomatal opening by activating ROS-related ion transport.
METHODS
Plant Materials and Growth Condition
Arabidopsis thaliana,including two wild-type ecotypes(Was-silewskija(ws)and Columbia-0(col-0)),two G a null mutants (gpa1-1and gpa1-2,background ws;seeds donated by Profes-sor Alan Jones,University of North Carolina at Chapel Hill),an NADPH oxidase null mutant(atrbohD/F,background col-0;seeds donated by Dr M.A.Torres,University of North Carolina at Chapel Hill)were used as plant materials.Plants were grown in vermiculite in a growth chamber under a15/9-h(light/dark) cycle(120–130l mol mà2sà1)with temperatures of22/18°C (day/night)and70%relative humidity.
Stomatal Bioassay
Abaxial epidermises were torn from2-week-old leaves.To inves-tigate stomatal movement in light,epidermal strips were incu-bated in MES buffer comprising(in mM)50KCl,10MES-Tris,0.1 CaCl2,pH6.1,and illuminated with a?uorescent lamp(120–130 l mol mà2sà1).Every30min,images of the epidermal strips were captured with a microscope(Olympus IX-71)equipped with a digital camera.To investigate stomatal movement in the dark,epidermal strips were incubated in MES buffer in a dark box.After1h,images of the epidermal strips were cap-tured.The images were analyzed with software Image J to ob-tain stomatal aperture data.At each time point,50–60stomata were randomly selected,and the mean value of stomatal aper-ture were calculated.Then,means6SE of the data from six in-dependent replicates were further calculated(n=6).To investigate the effects of different reagents on stomatal move-ment,the reagent solution diluted with MES buffer was infused gently into the bath solution.DPI was?rst dissolved with DMSO (Sigma)to make a10-mM stock solution,and then the stock so-lution was diluted with MES buffer to a?nal concentration of5 l M;the?nal concentration of DMSO in the solution was0.05%. As a control,added0.05%DMSO did not show any effect on stomatal movement(data not shown).
Confocal Laser Scanning Microscopy
To measure cytoplasmic ROS and guard cell viability,2’,7’-dichlorodihydro?uorescein diacetate(H2DCFDA,Molecular Probes)and?uorescein diacetate(FDA,Molecular Probes) were loaded into guard cells by incubation,respectively.Abax-ial epidermal strips were incubated in the dark in50l M H2DCFDA or FDA(diluted with MES buffer)for15min at 25°C and then washed three times.Fluorescence in guard cells was detected using a confocal laser scanning microscope(LSM 510,Carl Zeiss),using the488-nm argon laser.The light signal was captured with a500/560-nm emission?lter.To investigate the effects of reagents on cytoplasmic ROS,reagents diluted with MES buffer were infused into the bath solution gently. At each sampling time,at least30guard cells in three indepen-dent epidermal strips were recorded.Images of representative guard cells were edited with software Confocal Assistant4.0 and Adobe Photoshop7.0.To measure the relative?uorescent intensity in guard cells,the mean gray scale in guard cells was measured with software Image J and the mean6SE of gray scale in30guard cells was calculated.
Measurement of Ca2+and H+Fluxes
Net Ca2+and H+?uxes were measured by the Xuyue(Beijing) Science and Technology Co.Ltd.(https://www.wendangku.net/doc/897859299.html,)using the non-invasive micro-test system(NMT;BIO-IM,Younger USA
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862Hao et al.?ATP Promotes Stomatal Opening of Arabidopsis thaliana
Amherst,MA,USA)as described previously(Shabala et al., 1997;Sun et al.,2009).Abaxial epidermal strips were mounted in a Perspex chamber using double-sided adhesive tape.To measure Ca2+?ux,epidermal strips were immersed in a3-ml as-say solution comprising(in mM)50KCl,0.1CaCl2,10MES,and Tris base,pH6.1.To measure H+?ux,epidermal strips were im-mersed in a3-ml assay solution comprising(in mM)0.1KCl,0.1 CaCl2,0.5MES,and Tris base,pH6.1.Ion-selective microelectr-odes with an external tip diameter of2–3l m were pulled from borosilicate glass capillaries.Electrodes were calibrated before and after use.The electrodes were back-?lled with the appro-priate solution(100mM CaCl2for the Ca2+electrode and40mM KH2PO4and15mM NaCl,pH7.0for the H+electrode)and then front-?lled with ionophore cocktails(catalogue no.21048for Ca2+and no.95293for H+;Sigma-Aldrich,St Louis,MO,USA). The prepared electrodes were calibrated with a set of standards (0.05–0.5mM Ca2+;pH5.5–6.5).The microelectrode was placed about2l m above the epidermal strips.During measurements, the electrode was moved between two positions(within a distance of10l m)above the surface of guard cells in epider-mal strips,in a square-wave manner with a5-s cycle.In each experiment,at least10guard cells were measured.A represen-tative curve was prepared and the mean6SE of the peak ion ?ux value was calculated.To calculate the mean value of max-imum ion in?ux or ef?ux velocity,data from three repetitive experiments were collected.The positive and negative values of ion?ux velocity represent ion in?ux and ef?ux velocity, respectively.
FUNDING
This work was supported by the National Science Foundation of China(No.30871297),the Program for New Century Excellent Tal-ents in University(No.NCET-10–0115),and the State Key Laboratory of Plant Cell and Chromosome Engineering(No.PCCE-2008-KF-03). No con?ict of interest declared.
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电力系统仿真软件介绍
电力系统仿真软件 电力系统仿真软件简介 一、PSAPAC 简介: 由美国EPRI开发，是一个全面分析电力系统静态和动态性能的软件工具。 功能：DYNRED（Dynamic Reduction Program）：网络化简与系统的动态等值，保留需要的节点。 LOADSYN（Load Synthesis Program）：模拟静态负荷模型和动态负荷模型。 IPFLOW（Interactive Power Flow Program）：采用快速分解法和牛顿－拉夫逊法相结合的潮流分析方法，由电压稳态分析工具和不同负荷、事故及发电调度的潮流条件构成。 TLIM（Transfer Limit Program）：快速计算电力潮流和各种负荷、事故及发电调度的输电线的传输极限。 DIRECT：直接法稳定分析软件弥补了传统时域仿真工作量大、费时的缺陷，并且提供了计算稳定裕度的方法，增强了时域仿真的能力。 LTSP（Long Term Stability Program）：LTSP是时域仿真程序，用来模拟大型电力系统受到扰动后的长期动态过程。为了保证仿真的精确性，提供了详细的模型和方法。 VSTAB（Voltage Stability Program）：该程序用来评价大型复杂电力系统的电压稳定性，给出接近于电压不稳定的信息和不稳定机理。为了估计电压不稳定状态，使用了一种增强的潮流程序，提供了一种接近不稳定的模式分析方法。 ETMSP（Extended Transient midterm Stability Program）：EPRI为分析大型电力系统暂态和中期稳定性而开发的一种时域仿真程序。为了满足大型电力系统的仿真，程序采用了稀疏技术，解网络方程时为得到最合适的排序采用了网络拓扑关系并采用了显式积分和隐式积分等数值积分法。 SSSP(Small－signal Stability Program)：该程序有助于局部电厂模式振荡和站间模式振荡的分析，由多区域小信号稳定程序(MASS)及大型系统特征值分析程序（PEALS）两个子程序组成。MASS程序采用了QR变换法计算矩阵的所有特征值，由于系统的所有模式都计算，它对控制的设计和协调是理想的工具；PEALS使用了两种技术：AESOPS算法和改进Arnoldi 方法，这两种算法高效、可靠，而且在满足大型复杂电力系统的小信号稳定性分析的要求上互为补充。 二、EMTP/ATP 简介: EMTP是加拿大H.W.Dommel教授首创的电磁暂态分析软件,它具有分析功能多、元件模型全和运算结果精确等优点,对于电网的稳态和暂态都可做仿真分析，它的典型应用是预测电力系统在某个扰动（如开关投切或故障）之后感兴趣的变量随时间变化的规律，将EMTP 的稳态分析和暂态分析相结合，可以作为电力系统谐波分析的有力工具。 ATP（The alternative Transients Program）是EMTP的免费独立版本，是目前世界上电磁暂态分析程序最广泛使用的一个版本, 它可以模拟复杂网络和任意结构的控制系统，数学模型广泛，除用于暂态计算，还有许多其它重要的特性。ATP程序正式诞生于1984年，由Drs.
几款主流电子电路仿真软件优缺点比较
几款主流电子电路仿真软件优缺点比较 电子电路仿真技术是当今相关专业学习者及工作者必须掌握的技术之一，它有诸多优点：第一，电子电路仿真软件一般都有海量而齐全的电子元器件库和先进的虚拟仪器、仪表，十分方便仿真与测试；第二，仿真电路的连接简单快捷智能化，不需焊接，使用仪器调试不用担心损坏；大大减少了设计时间及金钱的成本；第三，电子电路仿真软件可进行多种准确而复杂的电路分析。 随着电子电路仿真技术的不断发展，许多公司推出了各种功能先进、性能强劲的仿真软件。既然它们能百家争鸣，那么肯定是在某些方面各有优劣的。下面就针对几款主流电子电路仿真软件的优缺点进行比较。 (1) Multisim 在模电、数电的复杂电路虚拟仿真方面，Multisim是当之无愧的一哥。它有形象化的极其真实的虚拟仪器，无论界面的外观还是内在的功能，都达到了的最高水平。它有专业的界面和分类，强大而复杂的功能，对数据的计算方面极其准确。在我们参加电子竞赛的时候，特别是模拟方向的题目，我们用得最多的仿真软件就是Multisim。同时，Multisim不仅支持MCU，还支持汇编语言和C语言为单片机注入程序，并有与之配套的制版软件NI Ultiboard10，可以从电路设计到制板layout一条龙服务。 Multisim的缺点是，软件过于庞大，对MCU的支持不足，制板等附加功能比不上其他的专门的软件。 （2）Tina Tina的界面简单直观，元器件不算多，但是分类很好，而且TI公司的元器件最齐全。在比赛时经常用到TI公司的元器件，当在Multisim找不到对应的器件时，我们就会用到Tina来仿真。 Tina的缺点是，功能相对较少，对TI公司之外的元器件支持较少。 (3) Proteus
基于MATLAB的电力系统仿真
《电力系统设计》报告题目: 基于MATLAB的电力系统仿 学院：电子信息与电气工程学院 班级: 13级电气 1 班 姓名:田震 学号: 日期：2015年12月6日 基于MATLAB的电力系统仿真 摘要：目前，随着科学技术的发展和电能需求量的日益增长，电力系统规模越来 越庞大，超高压远距离输电、大容量发电机组、各种新型控制装置得到了广泛的应用，这对于合理利用能源，充分挖掘现有的输电潜力和保护环境都有重要意义。另一方面，随着国民经济的高速发展，以城市为中心的区域性用电增长越来越快，大电网负荷中心的用电容量越来越大，长距离重负荷输电的情况日益普遍，电力系统在人们的生活和工作中担任重要角色，电力系统的稳定运行直接影响着人们的日常生活。从技术和安全上考虑直接进行电力试验可能性很小，因此迫切要求运用电力仿真来解决这些问题。 电力系统仿真是将电力系统的模型化、数学化来模拟实际的电力系统的运行，可以帮助人们通过计算机手段分析实际电力系统的各种运行情况，从而有效的了解电力系统概况。本文根据电力系统的特点，利用MATLAB的动态仿真软件Simulink搭建了无穷大电源的系统仿真模型，得到了在该系统主供电线路电源端发生三相短路接地故障并由故障器自动跳闸隔离故障的仿真结果，并分析了这一暂态过程。通过仿真结果说明MATLAB 电力系统工具箱是分析电力系统的有效工具。 关键词：电力系统；三相短路；故障分析；MATLAB仿真 目录 一．前言.............................................. 二．无穷大功率电源供电系统仿真模型构建............... 1.总电路图的设计......................................
《ATP的主要来源——细胞呼吸》知识点总结
《ATP的主要来源——细胞呼吸》知识 点总结 《ATP的主要——细胞呼吸》知识点总结 一、相关概念： 、呼吸作用：指有机物在细胞内经过一系列的氧化分解，最终生成二氧化碳或其它产物，释放出能量并生成ATP的过程。根据是否有氧参与，分为：有氧呼吸和无氧呼吸 2、有氧呼吸：指细胞在有氧的参与下，通过多种酶的催化作用下，把葡萄糖等有机物彻底氧化分解，产生二氧化碳和水，释放出大量能量，生成ATP的过程。 3、无氧呼吸：一般是指细胞在无氧的条件下，通过酶的催化作用，把葡萄糖等有机物分解为不彻底的氧化产物，同时释放出少量能量的过程。 4、发酵：微生物的无氧呼吸。 五、有氧呼吸与无氧呼吸的比较： 呼吸方式 有氧呼吸 无氧呼吸 不同点 场所 细胞质基质，线粒体基质、内膜 细胞质基质
条件 氧气、多种酶 无氧气参与、多种酶 物质变化 葡萄糖彻底分解，产生 co2和H2o 葡萄糖分解不彻底，生成乳酸或酒精等 能量变化 释放大量能量，形成大量ATP 释放少量能量，形成少量ATP 六、影响呼吸速率的外界因素： 、温度：温度通过影响细胞内与呼吸作用有关的酶的活性来影响细胞的呼吸作用。 温度过低或过高都会影响细胞正常的呼吸作用。在一定温度范围内，温度越低，，细胞呼吸越弱;温度越高，细胞呼吸越强。 2、氧气：氧气充足，则无氧呼吸将受抑制;氧气不足，则有氧呼吸将会减弱或受抑制。 3、水分：一般来说，细胞水分充足，呼吸作用将增强。但陆生植物根部如长时间受水浸没，根部缺氧，进行无氧呼吸，产生过多酒精，可使根部细胞坏死。 4、co2：环境co2浓度提高，将抑制细胞呼吸，可用此
原理来贮藏水果和蔬菜。 七、呼吸作用在生产上的应用： 、作物栽培时，要有适当措施保证根的正常呼吸，如疏松土壤等。 2、粮油种子贮藏时，要风干、降温，降低氧气含量，则能抑制呼吸作用，减少有机物消耗。 3、水果、蔬菜保鲜时，要低温或降低氧气含量及增加二氧化碳浓度，抑制呼吸作用。 考点·助力 .体温的维持与细胞呼吸是怎样的关系？是否需要ATP 水解供能？ 人与鸟类和哺乳类维持体温的能量都是细胞呼吸。在这些生物的细胞呼吸过程中，葡萄糖等分子中稳定的化学能释放出来：除一部分储存在ATP中外，其余的则转化成热能，可以直接用于提升体温;ATP水解释放出的能量，除了维持各项生命活动外，有一部分也能转化成热能，用于提升体温。而维持体温的相对稳定，还需复杂的调节机制。 2.呼吸作用与物质的燃烧有什么共同点？ 两者的共同点是：都是物质的氧化分解过程;都能产生二氧化碳等产物，并且都释放出能量。
各种电路仿真软件的分析与比较
一．当今流行的电路仿真软件及其特性 电路仿真属于电子设计自动化（EDA）的组成部分。一般把电路仿真分为三个层次：物理级、电路级和系统级。教学中重点运用的为电路级仿真。 电路级仿真分析由元器件构成的电路性能，包括数字电路的逻辑仿真和模拟电路的交直流分析、瞬态分析等。电路级仿真必须有元器件模型库的支持，仿真信号和波形输出代替了实际电路调试中的信号源和示波器。电路仿真主要是检验设计方案在功能方面的正确性。电路仿真技术使设计人员在实际电子系统产生之前，就有可能全面地了解电路的各种特性。目前比较流行的电路仿真软件大体上说有：ORCAD、Protel、Multisim、TINA、ICAP/4、Circuitmaker、Micro-CAP 和Edison等一系列仿真软件。 电路仿真软件的基本特点： ●仿真项目的数量和性能： 仿真项目的多少是电路仿真软件的主要指标。各种电路仿真软件都有的基本功能是：静态工作点分析、瞬态分析、直流扫描和交流小信号分析等4项；可能有的分析是：傅里叶分析、参数分析、温度分析、蒙特卡罗分析、噪声分析、传输函数、直流和交流灵敏度分析、失真度分析、极点和零点分析等。仿真软件如SIMextrix只有6项仿真功能，而Tina6.0有20项，Protel、ORCAD、P-CAD等软件的仿真功能在10项左右。专业化的电路仿真软件有更多的仿真功能。对电子设计和教学的各种需求考虑的比较周到。例如TINA的符号分析、Pspice和ICAP/4的元件参数变量和最优化分析、Multisim的网络分析、CircuitMaker的错误设置等都是比较有特色的功能。 Pspice语言擅长于分析模拟电路，对数字电路的处理不是很有效。对于纯数字电路的分析和仿真，最好采用基于VHDL等硬件描述语言的仿真软件，例如，Altera公司的可编程逻辑器件开发软件MAX+plusII等。 ●仿真元器件的数量和精度： 元件库中仿真元件的数量和精度决定了仿真的适用性和精确度。电路仿真软件的元件库有数千个到1--2万个不等的仿真元件，但软件内含的元件模型总是落后于实际元器件的生产与应用。因此，除了软件本身的器件库之外，器件制造商的网站是元器件模型的重要来源。大量的网络信息也能提供有用的仿真模型。设计者如果对仿真元件模型有比较深入的研究，可根据最新器件的外部特性参数自定义元件模型，构建自己的元件库。对于教学工作者来说，软件内的元件模型库，基本上可以满足常规教学需要，主要问题在于国产元器件与国外元器件的替代，并建立教学中常用的国产元器件库。
基于MATLAB的电力系统仿真
《电力系统设计》报告 题目: 基于MATLAB的电力系统仿学院：电子信息与电气工程学院 班级: 13级电气 1 班 姓名:田震 学号: 20131090124 日期：2015年12月6日
基于MATLAB的电力系统仿真 摘要：目前，随着科学技术的发展和电能需求量的日益增长，电力系统规模越来越庞大，超高压远距离输电、大容量发电机组、各种新型控制装置得到了广泛的应用，这对于合理利用能源，充分挖掘现有的输电潜力和保护环境都有重要意义。另一方面，随着国民经济的高速发展，以城市为中心的区域性用电增长越来越快，大电网负荷中心的用电容量越来越大，长距离重负荷输电的情况日益普遍，电力系统在人们的生活和工作中担任重要角色，电力系统的稳定运行直接影响着人们的日常生活。从技术和安全上考虑直接进行电力试验可能性很小，因此迫切要求运用电力仿真来解决这些问题。 电力系统仿真是将电力系统的模型化、数学化来模拟实际的电力系统的运行，可以帮助人们通过计算机手段分析实际电力系统的各种运行情况，从而有效的了解电力系统概况。本文根据电力系统的特点，利用MATLAB的动态仿真软件Simulink搭建了无穷大电源的系统仿真模型，得到了在该系统主供电线路电源端发生三相短路接地故障并由故障器自动跳闸隔离故障的仿真结果，并分析了这一暂态过程。通过仿真结果说明MATLAB电力系统工具箱是分析电力系统的有效工具。 关键词：电力系统；三相短路；故障分析；MATLAB仿真
目录 一．前言 (4) 二．无穷大功率电源供电系统仿真模型构建 (5) 1.总电路图的设计 (5) 2.各个元件的参数设定 (6) 2.1供电模块的参数设定 (6) 2.2变压器模块的参数设置 (6) 2.3输电线路模块的参数设置 (7) 2.4三相电压电流测量模块 (8) 2.5三相线路故障模块参数设置 (8) 2.6三相并联RLC负荷模块参数设置 (9) 3.仿真结果 (9)
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人教版高一下册《ATP的主要来源细胞呼吸》知识点
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条件 氧气、多种酶 无氧气参与、多种酶 物质变化 葡萄糖彻底分解，产生 CO2和H2O 葡萄糖分解不彻底，生成乳酸或酒精等 能量变化 释放大量能量(1161kJ被利用，其余以热能散失)，形成大量ATP 释放少量能量，形成少量ATP 六、影响呼吸速率的外界因素： 1、温度：温度通过影响细胞内与呼吸作用有关的酶的活性来影响细胞的呼吸作用。 温度过低或过高都会影响细胞正常的呼吸作用。在一定温度范围内，温度越低，，细胞呼吸越弱;温度越高，细胞呼吸越强。 2、氧气：氧气充足，则无氧呼吸将受抑制;氧气不足，则有氧呼吸将会减弱或受抑制。 3、水分：一般来说，细胞水分充足，呼吸作用将增强。但陆生植物根部如长时间受水浸没，根部缺氧，进行无氧呼吸，产生过多酒精，可使根部细胞坏死。
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可以研究交直流电力系统问题，又能完成电力电子仿真及其非线性控制的多功能工具。
PSCAD由Manitoba HVDC research center开发。 3 PSASP PSASP由中国电力科学研究院开发。PSASP的功能主要有稳态分析、故障分析和机电暂态分析。稳态分析包括潮流分析、网损分析、最优潮流和无功优化、静态安全分析、谐波分析和静态等值等。 故障分析包括短路计算、复杂故障计算及继电保护整定计算。机电暂态分析包括暂态稳定计算、电压稳定计算、控制参数优化等。 4 ARENE 法国电力公司(EDF)开发的全数字仿真系统ARENE, 有实时仿真和非实时仿真版本。实时版本有： （1）RTP版本，硬件为HP公司基于HP-CONVE工作站的多CPU 并行处理计算机，该并行处理计算机的最大CPU数量已达32个，可以用于较大规模系统电磁暂态实时仿真； （2）URT版本，HP-Unix工作站，用于中小规模系统电磁暂态实时仿真； （3）PCRT版本，PC-Linux工作站，用于中小规模系统电磁暂态实时仿真。 ARENE实时仿真器可以进行如下物理装置测试：继电保护，自动装置，HVDC和FACTS控制器，可以用50微秒步长进行闭环电磁暂态实时仿真。ARENE不作机电暂态仿真。采用基于HP工作站的并行处理计算机，其软硬件扩展也受到计算机型号的制约。
ATP的主要来源-细胞呼吸知识梳理
ATP的主要来源－细胞呼吸知识梳理 一、细胞呼吸的方式 1．细胞呼吸： （1）实质：细胞内有机物进行一系列的＿＿＿＿＿，并且释放＿＿＿。 （2）产物：ATP、＿＿＿或其他产物。 （3）类型：＿＿＿＿＿＿＿和＿＿＿＿＿＿＿。 2．对比实验： （1）概念：设置＿＿＿＿＿＿＿＿＿实验组，通过对结果的＿＿＿＿＿＿，来探究某种因素与实验对象的关系的实验。 （2）实例：探究酵母菌细胞呼吸的方式，需要设置＿＿＿＿和＿＿＿＿两种条件进行对比。 二、有氧呼吸 1．概念： 是指细胞在＿＿＿的参与下，通过多种酶的＿＿＿＿＿＿，把＿＿＿＿＿等有机物彻底氧化分解，产生＿＿＿和＿＿＿，释放能量，生成许多＿＿＿＿＿的过程。 2．特点： （1）条件：有氧参与，多种酶催化。 （2）反应物质：＿＿＿＿＿＿＿等有机物。 （3）过程特点：彻底＿＿＿＿＿。 （4）生成物质：＿＿＿＿＿、水、＿＿＿＿＿。 3．场所： （1）第一阶段：细胞质基质。 （2）第二阶段：＿＿＿＿＿＿＿。 （3）第三阶段：＿＿＿＿＿＿＿。 4．反应式： ＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿。 5．过程： （1）第一阶段：1分子葡萄糖生成＿＿＿＿，并产生少量［H］，同时放出＿＿＿＿能量。（2）第二阶段：丙酮酸和＿＿＿彻底分解生成CO2和＿＿＿＿，同时放出＿＿＿＿能量。（3）第三阶段：＿＿＿＿与氧结合生成水，同时放出＿＿＿＿能量。 6．能量释放： 总的来说，1 mol葡萄糖彻底氧化分解，共释放能量＿＿＿＿kJ，有＿＿＿＿kJ左右的能量储存在ATP中，其余能量以＿＿＿形式散失掉了。 三、无氧呼吸 1．特点： （1）条件：＿＿＿＿＿、多种酶参与催化。 （2）反应物质：葡萄糖等有机物。 （3）过程特点：＿＿＿＿＿＿＿＿＿＿。 （4）能量释放：释放＿＿＿＿＿＿。 （5）生成物质：＿＿＿＿＿＿＿＿＿＿或＿＿＿＿＿。 2．场所：始终在＿＿＿＿＿＿＿内进行。 3．过程： （1）第一阶段：与有氧呼吸的＿＿＿＿＿阶段完全相同。 （2）第二阶段：丙酮酸在不同酶的催化作用下，分解成酒精和＿＿＿，或者转化为乳酸。
电力系统分析软件介绍
[转]转载：电力系统分析软件介绍来源：崔明建的日志 一、PSAPAC 简介:由美国EPRI开发，是一个全面分析电力系统静态和动态性能的软件工具。 功能： DYNRED（Dynamic Reduction Program）：网络化简与系统的动态等值，保留需要的节点。LOADSYN（Load Synthesis Program）：模拟静态负荷模型和动态负荷模型。 IPFLOW（Interactive Power Flow Program）：采用快速分解法和牛顿－拉夫逊法相结合的潮流分析方法，由电压稳态分析工具和不同负荷、事故及发电调度的潮流条件构成。 TLIM（Transfer Limit Program）：快速计算电力潮流和各种负荷、事故及发电调度的输电线的传输极限。 DIRECT：直接法稳定分析软件弥补了传统时域仿真工作量大、费时的缺陷，并且提供了计算稳定裕度的方法，增强了时域仿真的能力。 LTSP（Long Term Stability Program）：LTSP是时域仿真程序，用来模拟大型电力系统受到扰动后的长期动态过程。为了保证仿真的精确性，提供了详细的模型和方法。 VSTAB（Voltage Stability Program）：该程序用来评价大型复杂电力系统的电压稳定性，给出接近于电压不稳定的信息和不稳定机理。为了估计电压不稳定状态，使用了一种增强的潮流程序，提供了一种接近不稳定的模式分析方法。 ETMSP（Extended Transient Midterm Stability Program）：EPRI为分析大型电力系统暂态和中期稳定性而开发的一种时域仿真程序。为了满足大型电力系统的仿真，程序采用了稀疏技术，解网络方程时为得到最合适的排序采用了网络拓扑关系并采用了显式积分和隐式积分等数值积分法。 SSSP(Small－signal Stability Program)：该程序有助于局部电厂模式振荡和站间模式振荡的分析，由多区域小信号稳定程序(MASS)及大型系统特征值分析程序（PEALS）两个子程序组成。MASS程序采用了QR变换法计算矩阵的所有特征值，由于系统的所有模式都计算，它对控制的设计和协调是理想的工具；PEALS使用了两种技术：AESOPS算法和改进Arnoldi方法，这两种算法高效、可靠，而且在满足大型复杂电力系统的小信号稳定性分析的要求上互为补充。 二、EMTP/ATP 简介: EMTP是加拿大H.W.Dommel教授首创的电磁暂态分析软件,它具有分析功能多、元件模型全和运算结果精确等优点,对于电网的稳态和暂态都可做仿真分析，它的典型应用是预测电力系统在某个扰动（如开关投切或故障）之后感兴趣的变量随时间变化的规律，将EMTP的稳态分析和暂态分析相结合，可以作为电力系统谐波分析的有力工具。 ATP（The Alternative Transients Program）是EMTP的免费独立版本，是目前世界上电磁暂态分析程序最广泛使用的一个版本, 它可以模拟复杂网络和任意结构的控制系统，数学模型广泛，除用于暂态计算，还有许多其它重要的特性。ATP程序正式诞生于1984年，由Drs. W. Scott Meyer 和Tsu-huei Liu,所组成的世界各地的用户组不断地发展。 ATP还配备有比TACS更灵活、功能更强的通用描述语言MODELS及图形输入程序ATPDraw。功能： 雷电过电压研究 操作过电压和故障 系统过电压研究 接地等现象的快速暂态分析