Mechanical and electrical anisotropy in Mimosa pudica pulvini

Thigmonastic or seismonastic movements in Mimosa pudica, such as the response to touch, appear to be regulated by electrical, hydrodynamical and chemical signal transduction. The pulvinus of Mimosa pudica shows elastic properties, and we found that electrically or mechanically induced movements of the petiole were accompanied by a change of the pulvinus shape. As the petiole falls, the volume of the lower part of the pulvinus decreases and the volume of the upper part increases due to the redistribution of water between the upper and lower parts of the pulvinus. This hydroelastic process is reversible. During the relaxation of the petiole, the volume of the lower part of the pulvinus increases and the volume of the upper part decreases. Redistribution of ions between the upper and lower parts of a pulvinus causes fast transport of water through aquaporins and causes a fast change in the volume of the motor cells. Here, the biologically closed electrochemical circuits in electrically and mechanically anisotropic pulvini of Mimosa pudica are analyzed using the charged capacitor method for electrostimulation at different voltages. Changing the polarity of electrodes leads to a strong rectification effect in a pulvinus and to different kinetics of a capacitor discharge if the applied initial voltage is 0.5 V or higher. The electrical properties of Mimosa pudica''s pulvini were investigated and the equivalent electrical circuit within the pulvinus was proposed to explain the experimental data. The detailed mechanism of seismonastic movements in Mimosa pudica is discussed.Key words: electrophysiology, plant electrostimulation, pulvinus, Mimosa pudica, charged capacitor method, electrical circuits, ion channels     

Change in the actin cytoskeleton during seismonastic movement of Mimosa pudica

The seismonastic movement of Mimosa pudica is triggered by a sudden loss of turgor pressure. In the present study, we compared the cell cytoskeleton by immunofluorescence analysis before and after movement, and the effects of actin- and microtubule-targeted drugs were examined by injecting them into the cut pulvinus. We found that fragmentation of actin filaments and microtubules occurs during bending, although the actin cytoskeleton, but not the microtubules, was involved in regulation of the movement. Transmission electron microscopy revealed that actin cables became loose after the bending. We injected phosphatase inhibitors into the severed pulvinus to examine the effects of such inhibitors on the actin cytoskeleton. We found that changes in actin isoforms, fragmentation of actin filaments and the bending movement were all inhibited after injection of a tyrosine phosphatase inhibitor. We thus propose that the phosphorylation status of actin at tyrosine residues affects the dynamic reorganization of actin filaments and causes seismonastic movement.     

Aquaporins and plant leaf movements

BaCKGROUND: Plant leaf movements can be mediated by specialized motor organs, the pulvini, or can be epinastic (i.e. based on different growth velocities of the adaxial and abaxial halves of the leaf). Both processes are associated with diurnally regulated increases in rates of membrane water transport, which in many cases has been shown to be facilitated by aquaporins. Rhythmic leaf movements are known from many plant species, but few papers deal with the involvement of aquaporins in such movements. SCOPE: Many details of the architecture and function of pulvini were worked out by Ruth Satter and co-workers using Samanea saman as a model organism. More recently a contribution of aquaporins to pulvinar movement in Samanea was demonstrated. Another model plant to study pulvinus-mediated leaf movements is Mimosa pudica. The contribution of both plasma membrane- and tonoplast-localized aquaporins to the seismonastic leaf movements in Mimosa was analysed. In tobacco, as an example of epinastic leaf movement, it was shown that a PIP1 aquaporin family member is an important component of the leaf movement mechanism.     

Comparative Histocytology of the Petiole and the Main Pulvinus in Mimosa pudica L.

In Mimosa pudica, the main pulvinus, which brings about leafmovements, presents unusual structural characteristics in comparisonwith the petiole. Peculiar cellular features which exist inthe cortex, epidermis, parenchyma and endodermal regions includethe shape of the cells, their disposition and the location ofthe organelles. The central cylinder of the petiole is surrounded only by afew parenchyma layers whereas the central cylinder of the pulvinusforms a narrow central core enclosed in numerous cortical parenchymalayers. The phloem of the pulvinus contains collenchymatouscells towards the outside and possesses companion cells withwall ingrowths; these phloem members do not exist in the petiole.Xylem and protoxylem parenchyma cells of the petiole possesswall ingrowths which do not occur in homologous cells of thepulvinus. Moreover the pith of the pulvinus is composed of smallfibriform elements similar to the xylem fibriform elements ofthe organ. The structures observed may facilitate exchanges between cellsin the petiole and in the pulvinus. The predominant functionsof the organs relative to lateral and longitudinal transferof nutrients and conduction of stimuli are discussed. Mimosa pudica L., sensitive plant, pulvinus, ultrastructure, conduction of stimuli, leaf movement     

Distribution and Activity of the Plasma Membrane H+-ATPase in Mimosa pudica L. in Relation to Ionic Fluxes and Leaf Movements

Plasma membrane H+-ATPase was immunolocalized in several cell types of the sensitive plant Mimosa pudica L., and transmembrane potentials were measured on cortical cells. In comparison with the nonspecialized cortical cells of the petiole or stem, the proton pump was highly expressed in motor cells. These immunological data are in close agreement with electrophysiological data, because the active component of the transmembrane potential was low in the nonspecialized cortical cells and high in motor cells. Therefore, motor cells contain the plasma membrane H+-ATPase required to mediate the ionic fluxes that are involved in circadian leaf movements and that are necessary to recover the turgor potential that is considerably affected by the large K+ and Cl- efflux associated with seismonastic movement. With the exception of sieve tubes, the phloem also had a high density of H+-ATPase. This suggests that the recovery of the transmembrane ionic gradients (K+ and Cl-), which is affected by various stimuli, is more energized by the companion and parenchyma cells than by the sieve elements. In addition, at the phloem/cortex interface collocytes displayed the required properties for lateral transduction of the action potential toward the pulvinal motor cells.     

The distribution of ATPase activities in purified transverse tubular membranes

Vesiculated fragments of transverse tubules (TT) and sarcoplasmic reticulum (SR) membranes were purified from heterogeneous microsomal membrane fractions of chicken breast muscle by a modification of an iterative calcium-oxalate loading technique. The distribution of ATPase activities were determined for the TT and SR and were compared to enriched fractions of sarcolemma (SL) membranes. The TT membranes were characterized by high rates of magnesium-stimulated ATPase (Mg-ATPase) and 5′-nucleotidase activities but were virtually devoid of calcium-stimulated, magnesium-dependent ATPase (Ca,Mg-ATPase) activity. Moderate levels of a latent sodium and potassium-stimulated ATPase (Na,K-ATPase) were observed for TT membranes when unmasked with valinomycin and monensin. In contrast to the behavior of TT membranes, highly purified SR membranes displayed an active Ca,Mg-ATPase but negligible Na,K-ATPase, Mg-ATPase, and 5′-nucleotidase activities. High levels of Na,K-ATPase and 5′-nucleotidase activities were observed for SL membranes; however, the SL displayed no appreciable Ca,Mg-ATPase and Mg-ATPase activities. The lack of significant Mg-ATPase activity in the SR and SL fractions suggested that the Mg-ATPase was uniquely associated with the TT membranes. The TT Mg-ATPase was further characterized by its pH and temperature dependences, and its sensitivity to pharmacologic agents. The Mg-ATPase of the TT was insensitive to inhibition by sodium azide and oligomycin in concentrations shown to exert maximum inhibition on the F₁ ATPase of submitochondrial particles. The Mg-ATPase was also resistant to the effects of ouabain and orthovanadate in concentrations which abolished the Na,K-ATPase and Ca,Mg-ATPase activities of the SL and SR, respectively. The Mg-ATPase displayed temperature and pH optima (25 °C, pH 7.3) which were distinguishable from the Ca,Mg-ATPase (45 °, pH 7.0) of highly purified SR fractions but which were very similar to the temperature and pH dependencies of the mixed microsomal fractions (MMF) from which the TT membranes were derived. Similarities in the pH and temperature dependencies of the TT and MMF Mg-ATPases plus the absence of appreciable Mg-ATPase activity in highly purified SR membranes suggests that the “basic” Mg-ATPase often seen in crude SR fractions may originate from TT membrane contamination. The resistance of the TT Mg-ATPase to inhibition by the pharmacologic agents tested plus its unique temperature and pH dependences indicate that this ATPase is distinguishable from other ATPases and may, therefore, be of value as a specific biochemical marker for TT membranes.     

Distribution of Potassium, Chloride and Calcium and Capacity of Hydrogen Ion Excretion in Various Parts of the Mimosa Pudica Plant

The contents of K, Cl and Ca were determined in various partsof Mimosa pudica plant, namely in young internode (YI), agedinternode (AI), upper half (UP1), and lower half (LP1) of theprimary pulvinus, secondary pulvinus (P2), petiole (Pt) andleaflet blade (B1). Potassium is found in the following distributionYI = LP1 > P2 > UP1 > Pt > AI > B1 and is thuslocalized in parts showing a great metabolic activity. Chloridefollows the distribution of K except for the petiole and toa lesser extent for the young internode. Calcium content islow in the parts showing a high plasticity (pulvini and younginternode). A relationship is thus suggested between the amountof Ca and the rate of the movements which can be performed.The capacity for spontaneous and fusicoccin-induced H⁺ excretionis greater in the plant parts exhibiting the higher K content.This suggests that larger H⁺ fluxes may be required in tissuesshowing a high metabolic activity. Mimosa pudica, ion content, H⁺ excretion     

Myosin from pancreatic acinar carcinoma cells. Isolation, characterization and demonstration of heavy- and light-chain phosphorylation.

Myosin has been identified in a variety of non-muscle cells, and is believed to play a role in maintenance of cell shape, locomotion, cytokinesis, exocytosis and other cellular functions. In this paper we describe the purification of myosin from a pancreatic acinar-cell carcinoma of the rat which forms solid tumours, but retains many differentiated functions. The purified myosin was composed of a 200,000 Da heavy chain and two or three classes of light chains. Electron-microscopic examination of rotary-shadowed preparations revealed that individual molecules had two globular heads and a long tail measuring approx. 149 nm. The myosin was soluble in high-salt buffers and became sedimentable as the ionic strength was lowered. Examination of negative-stained preparations showed that this sedimentable myosin consisted of short, bipolar, thick filaments which had a strong tendency to aggregate in a head-to-head manner. The ATPase activity of the purified myosin was stimulated by EDTA or Ca2+, but not by Mg2+. In low ionic strength the Mg2+-dependent ATPase activity was activated by muscle f-actin. The pancreatic myosin bound to actin and could be dissociated by the addition of MgATP. Myosin purified from cells cultured in media containing [32P]Pi was phosphorylated on one of the light chains as well as the heavy chain. Thus pancreatic acinar cells contain a typical non-muscle myosin, and the subunits of this molecule are subject to post-translational modification by phosphorylation.     

Interaction of myosin with thin filaments during contraction and relaxation: effect of ionic strength

The influence of ionic strength on the isometric tension, stiffness, shortening velocity and ATPase activity of glycerol-treated rabbit psoas muscle fiber in the presence and the absence of Ca2+ has been studied. When the ionic strength of an activating solution (containing Mg2+-ATP and Ca2+) was decreased by varying the KCl concentration from 120 to 5 mM at 20 degrees C, the isometric tension and stiffness increased by 30% and 50%, respectively. The ATPase activity increased 3-fold, while the shortening velocity decreased to one-fourth. At 6 degrees C, similar results were obtained. These results suggest that at low ionic strengths ATP is hydrolyzed predominantly without dissociation of myosin cross-bridges from F-actin. In the absence of Ca2+, with decreasing KCl concentration the isometric tension and stiffness developed remarkably at 20 degrees C. However, the ATPase activity and shortening velocity were very low. At low ionic strength, even in the absence of Ca2+ myosin heads are bound to thin filaments. The development of the tension and stiffness were greatly reduced at 6 degrees C or at physiological ionic strength.     

Steady-state kinetic study on the inhibition of the adenosinetriphosphatase activity of dynein from Tetrahymena cilia by glycerol

The characteristics of glycerol-induced inhibition of the dynein ATPase extracted from Tetrahymena cilia were investigated. Fifty percent inhibition was observed at about 15% (v/v) glycerol with the 22S dynein Mg-ATPase. Ethylene glycol was equally inhibitory, while sucrose, a kind of polyol, was less effective. The glycerol-induced inhibition of the 22S dynein Mg-ATPase was not influenced by pH or by raising the ionic strength of the assay solution. An aqueous glycerol solution treated with anion or cation exchanger or charcoal was equally inhibitory to a non-treated solution. The inhibition was most likely to be due to glycerol or ethylene glycol itself, not to a contaminant. The inhibition of the 22S dynein Mg-ATPase was apparently noncompetitive: only the Vmax was reduced without a significant change in the apparent Km. The dynein ATPase is known to be inhibited potently by vanadate. Glycerol reduced the sensitivity of the dynein ATPase to the vanadate-induced inhibition. Glycerol exhibited a decelerating effect on the rate of the oxygen exchange between phosphate and water catalyzed by 22S dynein in the presence of ADP and Mg2+. If it is assumed that the rate constants of the ATP hydrolysis step are not affected by glycerol, it may be implied that the phosphate release from the E.ADP.P1 intermediate was decelerated by glycerol and that the deceleration of the phosphate release paralleled the reduction of the overall ATPase activity over a wide range of glycerol concentration.(ABSTRACT TRUNCATED AT 250 WORDS)     

A Mathematical Model on Water Redistribution Mechanism of?the?Seismonastic Movement of Mimosa Pudica

A theoretical model based on the water redistribution mechanism is proposed to predict the volumetric strain of motor cells in Mimosa pudica during the seismonastic movement. The model describes the water and ion movements following the opening of ion channels triggered by stimulation. The cellular strain is related to the angular velocity of the plant movement, and both their predictions are in good agreement with experimental data, thus validating the water redistribution mechanism. The results reveal that an increase in ion diffusivity across the cell membrane of <15-fold is sufficient to produce the observed seismonastic movement.     

Changes in myocardial contractile protein ATPases in chronically adrenalectomized rats with and without glucocorticoid replacement

Studies were conducted to examine the effects of chronic adrenalectomy (Adx) and adrenalectomy plus glucocorticoid replacement therapy on rat cardiac contractile protein ATPase activities. The Ca2+-dependent Mg-ATPase activity of myofibrils isolated from rat ventricles 3 weeks postadrenalectomy (Adx) was significantly decreased at all pCa2+ concentrations (P less than 0.01), compared to sham-operated (SO) rats. Similarly, Ca2+-, K+-EDTA, and actin-activated myosin ATPase activities of Adx rat hearts were markedly decreased below that of SO rats (P less than 0.01). Dexamethasone administration to Adx rats prevented the decrease of Ca2+- and K+-ATPase activities of myosin, but not of myofibrillar Ca2+-dependent Mg-ATPase or actin-activated myosin Mg-ATPase activities. These studies suggest that glucocorticoid insufficiency induced by adrenalectomy results in altered myocardial contractile protein ATPase activity which may underlie impaired cardiac performance.     

Calcium sensitivity of vertebrate skeletal muscle myosin

The calcium sensitivity of vertebrate skeletal muscle myosin has been investigated. Adenosinetriphosphatase (ATPase) activity was assayed in a reconstituted system composed of either purified rabbit myosin plus actin or myosin plus actin, tropomyosin, and troponin. The calcium sensitivity of actomyosin Mg-ATPase activity was found to be directly affected by the ionic strength of the assay medium. Actomyosin assayed at approximately physiological ionic strength (120 mM KCl) demonstrated calcium sensitivity which varied between 6 and 52%, depending on the myosin preparation and the age of the myosin. Mg-ATPase activity was increased when calcium was present in the assay medium at physiological ionic strength. Conversely, actomyosin Mg-ATPase activity assayed at a lower ionic strength (15 mM KCl) was inhibited by addition of calcium. Addition of tropomyosin and troponin to the assay increased the calcium sensitivity of the system at the physiological ionic strength still further (up to 99% calcium sensitivity) and conferred calcium sensitivity on the system at the lower ionic strength (greater than 90% calcium sensitivity). A correlation also existed between myosin's calcium sensitivity and the phosphorylated state of light chain 2.     

Isolation and characterization of myosin from amoebae of Physarum polycephalum

Myosin was isolated from amoebae of Physarum polycephalum and compared with myosin from plasmodia, another motile stage in the Physarum life cycle. Amoebal myosin contained heavy chains (Mr approximately 220,000), phosphorylatable light chains (Mr 18,000), and Ca2+-binding light chains (Mr 14,000) and possessed a two-headed long-tailed shape in electron micrographs after rotary shadow casting. In the presence of high salt concentrations, myosin ATPase activity increased in the following order: Mg-ATPase activity less than K-EDTA-ATPase activity less than Ca-ATPase activity. In the presence of low salt concentrations, Mg-ATPase activity was activated approximately 9-fold by skeletal muscle actin. This actin-activated ATPase activity was inhibited by micromolar levels of Ca2+. Amoebal myosin was indistinguishable from plasmodial myosin in ATPase activities and molecular shape. However, the heavy chain and phosphorylatable light chains of amoebal myosin could be distinguished from those of plasmodial myosin in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, peptide mapping, and immunological studies, suggesting that these are different gene products. Ca2+-binding light chains of amoebal and plasmodial myosins were found to be identical using similar criteria, supporting our hypothesis that the Ca2+-binding light chain plays a key role in the inhibition of actin-activated ATPase activity in Physarum myosins by micromolar levels of Ca2+.     

Properties and localization of Mg- and Ca-ATpase activities in wheat embryo cell nuclei]

The isolated nuclei of wheat embryo possess the ATPase activity. The addition of Mg2+ and Ca2+ significantly increases the activities of nuclear ATPases, whereas Hg2+, Cu2+ and Mn2+ inhibit the activity. The activating effect of Mg2+ is enhanced by an addition of Na and K ions. The activity of wheat embryo nuclear Mg-ATPase is higher than its Ca-ATPase activity; both ATPases also differ in their pH optima. Separation of total nuclear protein according to the solubility of its individual protein components in wheat and strong salt solutions, using the detergents, as well as ammonium sulfate precipitation and dialysis do not result in separation of Mg-activated and Ca-activated ATPases, although their levels of activities and ratios change in the course of fractionation. The Mg- and Ca-ATPase activities of the wheat embryo nuclei were found in the nuclear fraction of albumin, in nonhistone proteins and nuclear membranes. In the albumin nuclear fraction and subfractions of non-histone proteins the higher level of activity is observed in Ca-ATPase, whereas in the nuclei and soluble fractions of residual proteins in Mg-ATPase.     

Morphing structures and signal transduction in Mimosa pudica L. induced by localized thermal stress

Leaf movements in Mimosa pudica, are in response to thermal stress, touch, and light or darkness, appear to be regulated by electrical, hydrodynamical, and chemical signal transduction. The pulvinus of the M. pudica shows elastic properties. We have found that the movements of the petiole, or pinnules, are accompanied by a change of the pulvinus morphing structures. After brief flaming of a pinna, the volume of the lower part of the pulvinus decreases and the volume of the upper part increases due to the redistribution of electrolytes between these parts of the pulvinus; as a result of these changes the petiole falls. During the relaxation of the petiole, the process goes in the opposite direction. Ion and water channel blockers, uncouplers as well as anesthetic agents diethyl ether or chloroform decrease the speed of alert wave propagation along the plant. Brief flaming of a pinna induces bidirectional propagation of electrical signal in pulvini. Transduction of electrical signals along a pulvinus induces generation of an action potential in perpendicular direction between extensor and flexor sides of a pulvinus. Inhibition of signal transduction and mechanical responses in M. pudica by volatile anesthetic agents chloroform or by blockers of voltage gated ion channels shows that the generation and propagation of electrical signals is a primary effect responsible for turgor change and propagation of an excitation. There is an electrical coupling in a pulvinus similar to the electrical synapse in the animal nerves.     

Partial purification of plant plasma membrane K+, Mg2+-ATPase by ion exchange chromatography

A purification procedure is presented which differs in three respects from other procedures for the purification of plant plasma membrane H⁺-pumping ATPase (EC 3.6.1.35) from various plants. Soybean ( Glycine max L. cv. Williams) hypocotyls were homogenized in the presence of physiological ionic strength and plasma membrane vesicles were purified by aqueous polymer two-phase partitioning. Plasma membrane vesicles were then solubilized in one step by using non-ionic detergent (either Triton X-100 or C₁₂E₈). The Mg-ATPase was separated by ion exchange chromatography from other solubilized membrane proteins. ATPase molecules bound to phosphocellulose fibers were eluted by a 0–1 M gradient of NaCl. The NaCl-eluted fractions contained a Mg-ATPase which showed the characteristics of Mg-ATPase present in the plasma membranes. The specific activity of the partially purified enzyme was 2–5 μmol mg⁻¹ min⁻¹ when it was reconstituted into proteoliposomes. This value is in good agreement with data obtained by other purification methods in the literature.     

Modulation of smooth muscle actomyosin ATPase by thin filament associated proteins

Caldesmon binds equally to both gizzard actin and actin containing stoichiometric amounts of bound tropomyosin. The binding of caldesmon to actin inhibits the actin-activation of the Mg-ATPase activity of phosphorylated myosin only when the actin contains bound tropomyosin. The reversal of this inhibition requires Ca2+-calmodulin; but it occurs without complete release of bound caldesmon. Although phosphorylation of the caldesmon occurs during the ATPase assay, a direct correlation between caldesmon phosphorylation and the release of the inhibited actomyosin ATPase is not consistently observed.     

Histochemical Observations on the Distribution of Adenosine Triphosphatase in Phloem and Motor Organs in Higher Plants

In a previous communication (Kuo 1964), it was shown by histochemical means that the phloem of cucurbit, as compared with the ground parenchyma, is particularly rich in adenosine triphosphatase (ATPase). A concurrent research by Yen et al. (1965) has succeeded in actually extracting from the vascular bundle of tobacco a crude protein fraction which not only possesses high ATPase activity, but also exhibits viscosity changes on addition of ATP or AMP. Such properties have been known to be characteristic of the contractile proteins constituting the muscle in animals. Although little is known about the actual role played in food transport by the living tissues in phloem, evidence has been accumulating that the active participation of the protoplasm in the phloem is necessary to facilitate sap movement. All these results have tempted us to think that higher plants, just like animals, also derive the energy required for performing mechanical work directly from ATP through the mediation of the contractile protein which is the ATPase itself. Accordingly, the present investigation is engaged in further histochemical observations to locate more precisely ATPase in the sieve element and to map out the distribution of the enzyme in various motor organs of higher plants, with the purpose in mind to see whether the map of enzyme distribution in the tissue has anything to do with its peculiar way of movement. 1. Presence of ATPase in the slime body of the functioning sieve element. In the functioning sieve element, high ATPase activity is displayed at the slime body and the connecting strands traversing the pores of the sieve plate (Plate Ⅰ, figs. 2, 3 & 4). However, as the pores of the sieve plate are partially blocked by the callose, the enzyme reaction becomes lessened. If the plate is completely covered by the callose pad, none could be detected. Since the slime body has been claimed by many workers to be pro- teinaceous in nature (cf. Esau 1950), there should be no surprise that it also possesses enzyme activity and contractile action. This seems to indicate that the slime body and the connecting strands are not mere hindrance to the sap flow but may actively participate in propelling the translocation stream. The fact that the intense ATPase reaction is given in the companion cell (Plate I, figs. 1 & 3) is in conformity with the common notion that the cell is actively involved in the normal functioning of phloem. 2. Enzyme distribution in various motor organs of different sensitivity. The ATPase content in the various motor organs (pulvinus, stamen, tendril, etc.) of different sensitivity has been compared histochemically, ranging from. 1) the highly sensitive organs; e.g. the pulvinus of Mimosa pudica (Plate Ⅱ, fig. 5) and of Oxalis piota (Plate Ⅱ, fig. 6), the stamen of Berberis Watsonae (Plate Ⅲ, fig. 10), the young tendril of Cucurbita maxima Duchesne and Vitis vinifera (Plate Ⅲ, figs. 11 & 12); 2) the moderately sensitive organs; e.g. the pulvinus of Sesbania cannabina (Plate Ⅱ, fig. 8); 3) the feebly sensitive or insensitive organs, e.g. the pulvinus of Robinia pseudoacacia (Plate Ⅱ, fig. 7), the stamen of Brassica campestris var. oleifera (Plate Ⅲ, fig. 9). From the results, it can be seen that the higher the sensitivity of the organ, the greater its enzyme activity. In addition to the morphological assymetry which is typical of plant motor organs, there also exists a physiological gradient, as evidenced by the uneven distribution of ATPase, usually being more intense on the more irritable side. The claim made recently by Aimi (1963) and others that the sudden collapse of the pulvinus of Mimosa on stimulation is not a direct result of the loss of turgidity as is generally assumed, but an immediate manifestation of the active vacuolar contraction in the motor cells is supported by the high ATPase content in the motor cells in our investigation.     

Movement of water in conjunction with plant movement visualized by NMR imaging

The water distribution in the pulvinus of Mimosa can be visualized by an NMR imaging technique. After stimulation of a Mimosa plant, water in the lower half of the main pulvinus disappeared, the water previously contained in this area seeming to be transferred to the upper half of the main pulvinus. Movement of the water in conjunction with Mimosa movement was visualized sequentially by a non-invasive NMR imaging procedure.