KT和Ca2+对绿豆下胚轴原生质体的体积和CaM含量的影响

以黄化绿豆幼苗下胚轴原生质体为材料,探讨钙信使系统在KT诱导原生质体体积变化中的作用。lμmol/L KT可诱导含钙培养液中绿豆下胚轴原生质体膨大,处理后30min达到最大体积。Ca2 通道阻断剂Verapamil、Ca2 通道竞争性抑制剂LaCl3和钙调素拮抗剂TFP、CPZ可明显抑制KT诱导的原生质体膨大。另一方面,无论是KT处理还是对照(CaCl2单独处理),原生质体内CaM含量均在处理后30min时达到峰值,前者是后者的5倍．在KT CaCl2处理液中加入5μmol/L．Verapamil、50μmol/L LaCl3、5μmol/L,TFP或CPZ后原生质体内CaM含量都大大降低。以上结果表明,CaM可能与Ca2 共同参与KT的信号传递。     

钙调素在IAA和6—BA诱导绿豆下胚轴原生质体膨大过程中的 …

含钙培养液和含激素培养液中的绿豆下胚轴原生质体在培养３０ｍｉｎ时分别检测到钙调素峰,在含钙培养液中加入ＩＡＡ和６－ＢＡ,ＣａＭ含量急剧降低,这与先前的试验结果即＾４５Ｃａ＾２＋积累增多和体积膨大正好对应。异搏定,ＬａＣｌ３,ＥＧＴＡ或Ｗ７可使激素＋ＣａＣｌ２处理的ＣａＭ含量不同程度地回升,甚至接近或超过对照的水平。     

钙在IAA诱导绿豆下胚轴原生质体膨大过程中的作用

含钙培养液(对照)和仅用IAA处理的原生质体的体积和~(45)Ca~(2 )放射性强度均无变化。IAA处理含钙培养液中的原生质体,5min后~(45)Ca~(2 )积累明显增多,体积开始膨大。处理30min时~(45)Ca~(2 )积累最多,此时原生质体的膨大效应最好;随后~(45)Ca~(2 )积累和膨大效应逐渐下降。K~ 、Zn~(2 )、Ba~(2 )、Mg~(2 )等也可在一定程度上代替Ca~(2 )使原生质体体积膨大。原生质体的吸水在膨大中起着一定作用。EGTA、LaCl_3和verapamil均抑制IAA诱导的原生质体~(45)Ca~(2 )积累和体积膨大。说明Ca~(2 )可能在6-BA诱导原生质体膨大的过程中起着重要作用。     

钙在6-BA诱导黄化绿豆幼苗下胚轴原生质体体积膨大中的作用

对照和仅用6-BA(无Ca~(2 ))处理的原生质体的体积均无变化。含钙培养液中的原生质体经6-BA处理后10min~(45)Ca~(2 )积累明显增多,15min后开始膨大;处理30min时~(45)Ca~(2 )积累最多,此时原生质体的膨大效应最好;随后~(45)Ca~(2 )积累和膨大效应逐渐下降。两者的时间进程十分相似。K~ 、Zn~(2 )、Ba~(2 )、Mg~(2 )等可在不同程度上代替Ca~(2 )的作用。EGTA、verapamil和LaCl_3处理均可使原生质体~(45)Ca~(2 )累积降到对照的水平,膨大效应完全消失。表明Ca~(2 )可能在6-BA诱导原生质体膨大的过程中起着重要作用。     

光敏色素对黄化绿豆幼苗下胚轴原生质体膨大的调节作用

红光引起黄化绿豆（ＰｈａｓｅｏｌｕｓｒａｄｉｔｕｓＬ．）幼苗下胚轴原生质体膨大,远红光可逆转红光的作用。这种可逆现象至少能在两个红光－远红光循环中观察到;膨大反应与红光光照强度和时间呈正相关,表明黄化绿豆幼苗下胚轴原生质体膨大是由光敏色素诱导的。红光引起的膨大只是在培养液中有Ｃａ２＋ 存在时才能发生,Ｍｇ２＋ 、Ｂａ２＋ 、Ｚｎ２＋ 或Ｋ＋ 均不能替代Ｃａ２＋ 的作用。膨大与原生质体吸水有一定关系     

钙-钙调素在零下低温诱导毛白杨扦插苗抗冻性中的作用

以零下低温锻炼和结合效应剂(CaCl2、钙离子螯合剂EGTA、钙离子通道阻断剂LaCl3或钙调素拮抗剂CPZ)处理的低温锻炼下的毛白杨(Populus tomentosa)扦插苗为试材,对其体内丙.醛(M D A)及钙调素(CaM)含量,超氧化物歧化酶(SOD)、过氧化物酶(POD)及线粒体腺苷三磷酸酶(Ca2 -ATPase)活性,以及幼苗的半致死温度(LT50)分别进行测定.结果表明,低温锻炼不仅在一定程度上提高了幼苗 CaM含量,SOD、POD和线粒体Ca2 -ATPase活性,降低了MDA含量和幼苗半致死温度;而且减小了低温胁迫所引起的SOD、POD、线粒体Ca2 -ATPase活性和CaM含量的下降程度以及MDA的增加幅度,促进了胁迫后恢复过程中SOD、POD、线粒体Ca2 -ATPase活性和CaM水平的迅速回升以及MDA的下降.在低温锻炼的同时,用CaCl2处理能加强低温锻炼的效果,但这种效应可被EGTA、LaCl3或CPZ处理抑制.经或未经CaCl2处理的低温锻炼后,幼苗中CaM含量的增加有助于SOD、POD和线粒体Ca2 -ATPase活性的提高,进而对幼苗抗冻性的提高有明显的促进作用.看来,Ca2 -CaM信号系统可能参与了SOD、POD和线粒体Ca2 -ATPase活性的调节和抗冻性的低温诱导.     

表油菜素内酯对绿豆上胚轴内源IAA及其氧化酶的影响

用0.5ppm表油菜素内酯处理绿豆幼苗,显著促进上胚轴伸长生长,若切除真叶则可抑制表油菜素内酯诱导的效应。三碘苯甲酸(TIBA)也可抑制表油菜素内酯促进的伸长生长。外源IAA能部分恢复TIBA的抑制效应。经处理的上胚轴内源IAA含量明显高于对照。暗示表油菜素内酯可能通过对内源IAA的调节来促进绿豆上胚轴的伸长生长。 表油菜素内酯处理的绿豆上胚轴组织中,与生长素降解密切相关的IAA氧化酶以及过氧化物酶活性均明显低于对照。     

光敏色素对黄化绿豆幼苗下胚轴原生质体钙吸收的调节

红光引起黄化绿豆(Phaseolus raditus L.)幼苗下胚轴原生质体积累~(45)Ca~(2 ),在光辐照度未达到饱和值前,~(45)Ca~(2 )积累量与光照强度或光照时间呈正相关;远红光可逆转红光引起的~(45)Ca~(2 )积累,~(45)Ca~(2 )积累的多寡取决于最后一次是照射红光还是远红光,表明光敏色素对Ca~(2 )吸收具有调节作用。     

4种钙素调节剂对紫花擎天凤梨花芽分化及内源激素含量的影响

以组培苗移栽2年的紫花擎天凤梨为试材,研究了外源乙烯催花条件下4种钙素调节剂(A23187、W-7、TFP、EGTA)处理对其花芽分化及内源激素含量的影响.结果表明:(1)4种处理均能使花芽分化过程中生长素(IAA)、玉米素(ZR)含量不同程度增加,并以A23187处理的IAA、ZR含量增加幅度最大.(2)赤霉酸(GA3)和脱落酸(ABA)含量在花芽孕育阶段先后下降至低谷,在花芽形态分化期又先后上升并出现高峰;ABA含量在A23187处理中下降早于其他处理,于处理3 d时首先降到最低,而在EGTA处理中下降速度最慢,至处理5 d时才降到最低值;在花芽孕育阶段,处理A23187的GA3含量下降最慢,但整体下降幅度最大;在此后花芽发端期各处理的GA3含量均出现高峰,但A23187和乙烯处理上升幅度均高于其他3个处理.(3)(ZR+ABA)/GA3、(ZR+IAA)/GA3比值在花芽孕育阶段上升并出现高峰,在花芽形态分化期下降到低谷.(4)4种处理花芽分化完成时间不一致,紫花擎天凤梨花芽分化在Ca2+促进剂A23187处理下提前,分化时间缩短;而在钙离子专一性螯合剂EGTA、钙调素(CaM)拮抗剂W-7和TFP处理下均得到延缓或抑制.研究发现,Ca2+-CaM信号系统参与了乙烯诱导的紫花擎天凤梨花芽分化过程且起着重要的调控作用.     

芦丁对绿豆幼苗营养生长的影响及其与IAA的相互作用

观察了植物体内的天然黄酮芦丁和吲哚乙酸(IAA)对绿豆幼苗营养生长的影响并测定胚轴中的芦丁和IAA含量.光照条件下芦丁(60μg/mL以下)处理对绿豆幼苗生长有一定促进作用,表现为胚轴和主根伸长加快、侧根数目增多、鲜重或干重增加;而光照条件下更高浓度芦丁(80μg/mL以上)处理及黑暗条件下芦丁(20～100μg/mL)处理对绿豆幼苗生长有抑制作用.当培养基中的芦丁浓度为60～80 μg/mL时,光照下的幼苗比暗处理的幼苗在胚轴中积累更多的芦丁;而芦丁浓度为40μg/mL以下和接近100μg/mL时幼苗在光照下累积的芦丁较暗处理的幼苗更少.0.1μg/mL以上的IAA促进芦丁的累积而进一步抑制幼苗胚轴和主根的伸长.当培养基中含有40 μg/mL的芦丁和0.5μg/mL的IAA时,胚轴中累积的芦丁达到高峰.芦丁降低黄化幼苗内源性IAA在胚轴中的累积,并抑制幼苗对IAA的吸收.     

钙在IAA诱导绿豆下胚轴原生质体膨大过程中的作用

This paper studied on the role of calcium in IAA-induced swelling of protoplasts isolated from hypocotyl in etiolated mung bean (Phaseolus radiatus L.) seedlings. Protoplasts incubated in CaCl2-bearing medium without hormone maintained a constant volume and a consistent intensity of 45Ca2+ radioactivity. To treat with IAA, they began to swell and continually swelled to the maximum volume 30 minutes later (Fig. 2). However, the protoplasts could not swell when IAA was added into the medium without CaCl2 (Fig. 1). It was suggested that Ca2+ may be necessary for IAA to induce protoplast swelling. And also, IAA enabled the protoplasts to swell in less extent with K+, Zn2+, Ba2+ or Mg2+ instead of Ca2+ (Fig. 3). Radioisotope experiments showed that K+ influx increased when K+ replaced Ca2+ (Fig. 4), and water absorption plays a role in the swelling (Fig. 5). 45Ca2+ accumulation in protoplasts treated by IAA was much higher than that of control, and the time course of 45Ca2+ accumulation was similar to that of protoplasts swelling (Fig. 6). 45Ca2+ level and the swelling of protoplasts sharply declined when EGTA, verapamil or LaCl3 was added into the medium (Table 1, 2 and 3). These results indicated that Ca2+ may play an important role in IAA-induced swelling.     

Ca^2＋-Calmodulin is Involved in Betacyanin Accumulation Induced by Dark in C3 Halophyte Suaeda salsa

The C3 halophyte Suaeda salsa was used to investigate the roles of Ca^2＋, Ca^2＋ channels, and calmodulin （CAM） in betacyanin metabolism. Seeds of S. salsa were cultured in both the dark and light for 3 days. The fresh weight and betacyanin content were much higher in S. salsa seedlings formed in the dark than in seedlings formed in the light. The addition of Ca^2＋ to the half-strength MS nutrient solution promoted betacyanin accumulation in the dark, whereas Ca^2＋ depletion by EGTA suppressed the dark-induced betacyanin accumulation in shoots of S. salsa. The Ca^2＋ channel blocker LaCl3 also inhibited dark-induced betacyanin accumulation. The highest activity of CaM and the maximum betacyanin content decreased by 51% and 45%, respectively, in shoots of S. salsa seedlings treated with the potent CaM antagonist chlorpromazine in the dark. Furthermore, the other CaM antagonist N-（6-aminohexyl）-5-chloro-l-naphthalenesulfonamide （W-7） also inhibited the activity of CaM and dark-dependent betacyanin accumulation, whereas its less active structural analog N-（6-aminohexyl）- 1-naphthalenesulfonamide （W-5） had little effect on the responses to dark of S. salsa seedlings. These results suggest that Ca^2＋, Ca^2＋-regulated ion channels, and CaM play an important role in dark-induced betacyanin accumulation in the shoots of the C3 halophyte S. salsa.     

Cationic specificity of a Ca2+-accumulating system in smooth muscle cell mitochondria

In the experiments conducted with application of an isotopic technique (45Ca2+) on the myometrium cells suspension treated by digitonin solution (0.1 mg/ml) some properties of Ca ions accumulation system in the mitochondria--cationic and substrate specificity as well as effects of Mg2+ and some other bivalent metals ions on the Ca2+ accumulation velocity have been estimated. Ca ions accumulation from the incubation medium containing 3 mM sodium succinate Na, 2 mM Pi (as potassium K(+)-phosphate buffer, pH 7.4 at 37 degrees C), 0.01 mM (40CaCl2 + 45CaCl2) and 100 nM thapsigargin--selective inhibiting agent of endoplasmatic reticulum calcium pump were demonstrated as detected just only in presence of Mg, while not Ni, Co or Cu ions. The increase of Mg2+ concentration from 1 x 10(-6) to 10(-3) M induced the ATP dependent transport activation in the myometrium mitochondria. Under [Mg2+] increase till 40 mM this cation essentially decreased Ca2+ accumulation (by 65% from the maximal value). The optimum for Ca2+ transport in the myometrium cells suspension is Mg2+ 10 mM concentration. Ka activation apparent constant along Mg2+ value (in presence 3 mM ATP and 3 mM sodium succinate) is 4.27 mM. The above listed bivalent metals decreased Mg2+, ATP-dependent accumulation of calcium, values of inhibition apparent constants for ions Co2+, Ni2+ and Cu2+ were--2.9 x 10(-4) M, 5.1 x 10(-5) M and 4.2 x 10(-6) M respectively. For Mg2+, ATP-dependent Ca2+ transport in the uterus myocytes mitocondria a high substrate specificity is a characteristic phenomenon in elation to ATP: GTP, CTP and UTP practically fail to provide for Ca accumulation process.     

The Changes of Ethylene Production and CaM Content in IAA-Treated Etiolated Mungbean Hypocotyl

When the segments of etiolated mungbean hypocotyl were treated with IAA it was observed that the contents of CaM in tissue which were determined by ELISA and ethylene production were increased with increasing the concentration of IAA. The time course of CaM content change was also similar to that of ethylene production. Some inhibitors, including CPZ, TFP, and CHI, inhibited both increased ethylene production and CaM content by IAA treatment. The activity of ACC synthase and EFE were inhibited by CPZ. Both of IAA-induced ethylene production and CaM content were affected by the level of Ca in segments as a result of pretreatment with EGTA, CaCI2 and H2O before the experiment. From these results it was suggested that the Ca and CaM play an important role in induction of ethylene production inmungbean hypocotyl by IAA.     

Ca2+-Calmodulin Modulates Ion Channel Activity in Storage Protein Vacuoles of Barley Aleurone Cells

Many plant ion channels have been identified, but little is known about how these transporters are regulated. We have investigated the regulation of a slow vacuolar (SV) ion channel in the tonoplast of barley aleurone storage protein vacuoles (SPV) using the patch-clamp technique. SPV were isolated from barley aleurone protoplasts incubated with CaCl2 in the presence or absence of gibberellic acid (GA) or abscisic acid (ABA). A slowly activating, voltage-dependent ion channel was identified in the SPV membrane. Mean channel conductance was 26 pS when 100 mM KCl was on both sides of the membrane, and reversal potential measurements indicated that most of the current was carried by K+. Treatment of protoplasts with GA3 increased whole-vacuole current density compared to SPV isolated from ABA- or CaCl2-treated cells. The opening of the SV channel was sensitive to cytosolic free Ca2+ concentration ([Ca2+]i) between 600 nM and 100 [mu]M, with higher [Ca2+]i resulting in a greater probability of channel opening. SV channel activity was reduced greater than 90% by the calmodulin (CaM) inhibitors W7 and trifluoperazine, suggesting that Ca2+ activates endogenous CaM tightly associated with the membrane. Exogenous CaM partially reversed the inhibitory effects of W7 on SV channel opening. CaM also sensitized the SV channel to Ca2+. In the presence of ~3.5 [mu]M CaM, specific current increased by approximately threefold at 2.5 [mu]M Ca2+ and by more than 13-fold at 10 [mu]M Ca2+. Since [Ca2+]i and the level of CaM increase in barley aleurone cells following exposure to GA, we suggest that Ca2+ and CaM act as signal transduction elements mediating hormone-induced changes in ion channel activity.     

Glyoxalase I from Brassica juncea is a calmodulin stimulated protein.

Brassica juncea glyoxalase I (S-lactoylglutathione-lyase, EC 4.4.1. 5) is a 56 kDa, heterodimeric protein. It requires magnesium (Mg2+) for its optimal activity. In this report we provide biochemical evidence for modulation of glyoxalase I activity by calcium/calmodulin (Ca2+/CaM). In the presence of Ca2+ glyoxalase I showed a significant (2.6-fold) increase in its activity. It also showed a Ca2+ dependent mobility shift on denaturing gels. Its Ca2+ binding was confirmed by Chelex-100 assay and gel overlays using 45CaCl2. Glyoxalase I was activated by over 7-fold in the presence of Ca2+ (25 microM) and CaM (145 nM) and this stimulation was blocked by the CaM antibodies and a CaM inhibitor, trifluroperazine (150 microM). Glyoxalase I binds to a CaM-Sepharose column and was eluted by EGTA. The eluted protein fractions also showed stimulation by CaM. The stimulation of glyoxalase I activity by CaM was maximum in the presence of Mg2+ and Ca2+; however, magnesium alone also showed glyoxalase I activation by CaM.     

Relationship of calmodulin and dopaminergic activity in the striatum

Increasing evidence suggests a relationship between dopaminergic activity in the striatum and the content of calmodulin (CaM), an endogenous Ca2+-binding protein. The content of CaM in striatal membranes is increased by treatments that produce supersensitivity in striatal membranes is increased by treatments that produce supersensitivity of striatal dopaminergic receptors such as chronic neuroleptic treatment or injection of 6-hydroxydopamine. Concomitant with the increase in CaM is a greater sensitivity of adenylate cyclase to dopamine and an increase in Ca2+-sensitive phosphorylation in the striatal membranes. Procedures that result in dopaminergic subsensitivity, such as amphetamine treatment, increase the cytosolic content of CaM that can subsequently activate Ca2+ and CaM-dependent phosphodiesterase activity. In vitro studies have demonstrated that CaM and Ca2+ can stimulate basal adenylate cyclase activity in a striatal particulate fraction as well as increase the sensitivity of the enzyme to dopamine. Ca2+ and CaM most likely affect the dopamine-sensitive adenylate cyclase by interacting with guanyl nucleotides, which are required for dopamine sensitivity. It is concluded that a change in CaM concentration and/or location occurs during conditions of altered dopaminergic sensitivity in the striatum. These changes in CaM coupled with potential alterations in the Ca2+ concentration could modulate the sensitivity of the dopamine system and many CaM-dependent enzymes.