scholarly journals Stochastic Spatial Heterogeneity in Activities of H+-ATP-ases in Electrically Connected Plant Cells Decreases Threshold for Cooling-Induced Electrical Responses

2021 ◽  
Vol 22 (15) ◽  
pp. 8254
Author(s):  
Ekaterina Sukhova ◽  
Daria Ratnitsyna ◽  
Vladimir Sukhov
Keyword(s):  
Spatial Heterogeneity ◽  
Action Potentials ◽  
Higher Plants ◽  
Electrical Response ◽  
Plant Cells ◽  
Excitable Cells ◽  
Molecular Transporters ◽  
Positive Shift ◽  
Stochastic Heterogeneity ◽  
Electrical Responses

H+-ATP-ases, which support proton efflux through the plasma membrane, are key molecular transporters for electrogenesis in cells of higher plants. Initial activities of the transporters can influence the thresholds of generation of electrical responses induced by stressors and modify other parameters of these responses. Previously, it was theoretically shown that the stochastic heterogeneity of individual cell thresholds for electrical responses in a system of electrically connected neuronal cells can decrease the total threshold of the system (“diversity-induced resonance”, DIR). In the current work, we tested a hypothesis about decreasing the thresholds of generation of cooling-induced electrical responses in a system of electrically connected plant cells with increasing stochastic spatial heterogeny in the initial activities of H+-ATP-ases in these cells. A two-dimensional model of the system of electrically connected excitable cells (simple imitation of plant leaf), which was based on a model previously developed in our works, was used for the present investigation. Simulation showed that increasing dispersion in the distribution of initial activities of H+-ATP-ases between cells decreased the thresholds of generation of cooling-induced electrical responses. In addition, the increasing weakly influenced the amplitudes of electrical responses. Additional analysis showed two different mechanisms of the revealed effect. The increasing spatial heterogeneity in activities of H+-ATP-ases induced a weak positive shift of the membrane potential at rest. The shift decreased the threshold of electrical response generation. However, the decreased threshold induced by increasing the H+-ATP-ase activity heterogeneity was also observed after the elimination of the positive shift. The result showed that the “DIR-like” mechanism also participated in the revealed effect. Finally, we showed that the standard deviation of the membrane potentials before the induction of action potentials could be used for the estimation of thresholds of cooling-induced plant electrical responses. Thus, spatial heterogeneity in the initial activities of H+-ATP-ases can be a new regulatory mechanism influencing the generation of electrical responses in plants under actions of stressors.

scholarly journals The Development of the Rhabdom and the Appearance of the Electrical Response in the Insect Eye

1962 ◽  
Vol 46 (1) ◽  
pp. 143-157 ◽  
Author(s):  
Eisuke Eguchi ◽  
Kén-Ichi Naka ◽  
Masutaro Kuwabara
Keyword(s):  
Bombyx Mori ◽  
Action Potentials ◽  
Photochemical Reaction ◽  
Compound Eye ◽  
Electrical Response ◽  
Photic Stimulation ◽  
Electron Microscopic ◽  
Microscopic Studies ◽  
Insect Eye ◽  
Electrical Responses

Electron microscopic studies on the development of the rhabdom in the compound eye of the silkworm moth and pupa (Bombyx mori) were carried out in parallel with the recording of the electrical response to photic stimulation. No electrical response to photic stimulation was recorded from the pupal compound eye which had no trace of differentiation of the rhabdom. With the differentiation of development of the rhabdom in the pupal compound eye, electrical responses could be recorded, and the amplitude of such electrical responses increased with the progress of development of the rhabdom. These observations suggest that the rhabdom is probably the site of the photochemical reaction which leads to the generation of the slow retinal action potentials.

Cellular pathways of the conducted electrical response in arterioles of hamster cheek pouch in vitro

1995 ◽  
Vol 269 (6) ◽  
pp. H2031-H2038 ◽  
Author(s):  
J. Xia ◽  
T. L. Little ◽  
B. R. Duling
Keyword(s):  
Electrical Response ◽  
Electrical Current ◽  
Cell Types ◽  
Cheek Pouch ◽  
Resting Membrane Potential ◽  
Hamster Cheek Pouch ◽  
Cellular Pathways ◽  
Current Flows ◽  
Electrical Responses

We have previously shown that conducted vasomotor responses follow patterns that are consistent with a passive spread of electrical current along the length of the arterioles [(Xia and Duling, Am. J. Physiol. 269 (Heart Circ. Physiol. 38): H2022-H2030, 1995]. In this study, we define the cells through which the current flows. Isolated arterioles of hamster cheek pouch were used. The mean resting membrane potential (RMP) for randomly sampled arteriolar cells was -67 mV. When cell types were identified by dye injection, the RMPs were -68 and -67 mV for smooth muscle (SM) and endothelium (EC), respectively. Pulses of KCl induced transient, monophasic depolarizations at the site of stimulation (local), which were conducted decrementally along the length of the arteriole over several millimeters. During electrical conduction, three patterns of responses could be observed, but identical patterns of the conducted electrical responses were always observed in SM and EC. Phenylephrine stimulation also caused transient local and conducted depolarizations in both SM and EC. As with KCl stimuli, shapes of conducted electrical responses were identical in records made in both cell types. The results suggest that SM and EC are electrically coupled both homocellularly and heterocellularly.

Calcium/Calmodulin Affects Microtubule Stability in Lysed Protoplasts

1991 ◽  
Vol 100 (2) ◽  
pp. 311-317
Author(s):  
RICHARD J. CYR
Keyword(s):  
Cell Cycle ◽  
Dynamic Behavior ◽  
Growth And Development ◽  
Higher Plants ◽  
Plant Cells ◽  
Microtubule Stability ◽  
A Cell ◽  
Cycle Dependent ◽  
Carrot Protoplasts

Microtubules (Mts) are found in four distinct arrays appearing sequentially in a cell-cycle-dependent fashion within the cells of higher plants. Additionally, the cortical Mts of non-cycling cells are spatially altered in a variety of differentiated states. Information regarding the molecular details underlying these Mt-reorientation events in plant cells is scarce. Moreover, it is unclear how cytoskeletal behavior integrates with the myriad of other cellular activities that are altered concomitantly in both differentiating and cycling cells. Data are presented herein to indicate that calcium, in the form of a Ca2+/calmodulin complex, can alter the behavior of Mts in lysed carrot protoplasts. Mechanistically, we show that Ca2+/calmodulin most likely interacts with Mts via associations with microtubule associated pro- teins (MAPS). These results are discussed with reference to how Ca2+ may alter the dynamic behavior of Mts during growth and development.

Excitability and electrical response of ischemic heart muscle

1960 ◽  
Vol 198 (6) ◽  
pp. 1143-1147 ◽  
Author(s):  
Chandler McC. Brooks ◽  
Jerome L. Gilbert ◽  
Martin E. Greenspan ◽  
Gertrude Lange ◽  
Hector M. Mazzella
Keyword(s):  
Action Potential ◽  
Blood Supply ◽  
Heart Muscle ◽  
Action Potentials ◽  
Electrical Response ◽  
Left Ventricular ◽  
Ischemic Heart ◽  
Monophasic Action Potential ◽  
Ventricular Muscle ◽  
Refractory Periods

Measurements were made of the changes in the monophasic action potential, excitability, durations of the refractory periods and conduction times in an area of left ventricular muscle during the development of ischemia subsequent to ligation of the ramus descendens anterior. The degree and duration of the ischemia produced varied greatly and effects were related thereto. It was found that action potentials shortened as did the refractory periods; thresholds fell momentarily and then rose progressively as tissue responsiveness failed due to continuing ischemia. Latency of responses increased, the action potentials decreased in amplitude and alternation occurred before the tissue became completely unresponsive. Early re-establishment of a blood supply caused a reversal of the abnormalities. The significance of these changes to the origin of arrhythmias is discussed.

Calreticulin, a multifunctional Ca2+ binding chaperone of the endoplasmic reticulum

1998 ◽  
Vol 76 (5) ◽  
pp. 779-785 ◽  
Author(s):  
Marek Michalak ◽  
Paola Mariani ◽  
Michal Opas
Keyword(s):  
Gene Expression ◽  
Endoplasmic Reticulum ◽  
Posttranslational Modification ◽  
Storage Capacity ◽  
Higher Plants ◽  
Plant Cells ◽  
Steroid Sensitive ◽  
Endoplasmic Reticulum Chaperone ◽  
Precise Role ◽  
Cellular Ca

Calreticulin is a ubiquitous endoplasmic reticulum Ca2+ binding chaperone. The protein has been implicated in a variety of diverse functions. Calreticulin is a lectin-like chaperone and, together with calnexin, it plays an important role in quality control during protein synthesis, folding, and posttranslational modification. Calreticulin binds Ca2+ and affects cellular Ca2+ homeostasis. The protein increases the Ca2+ storage capacity of the endoplasmic reticulum and modulates the function of endoplasmic reticulum Ca2+-ATPase. Calreticulin also plays a role in the control of cell adhesion and steroid-sensitive gene expression. Recently, the protein has been identified and characterized in higher plants but its precise role in plant cells awaits further investigation.Key words: calreticulin, endoplasmic reticulum, chaperone, Ca2+ binding protein.

Ion transport in plant cells

1971 ◽  
Vol 262 (842) ◽  
pp. 333-342 ◽  
Keyword(s):  
Ion Transport ◽  
Higher Plants ◽  
Plant Cells ◽  
Redox System ◽  
Cell Level ◽  
Sodium Potassium ◽  
High K ◽  
Cell Layers ◽  
Kinetics Of ◽  
Potassium Exchange

Work on ion transport in plant cells and tissues is largely concerned with the properties of cells rather than of cell layers, and the evidence is on the whole against an important role for asymmetric ion transport across cell layers equivalent to animal epithelia. Cells structurally specialized for transport, having a large increase in surface area, seem to occur singly or in small groups, but not to be organized into closely packed layers; they are known as transfer cells and were described in a wide variety of situations by Gunning & Pate (1969). At the cell level, ion transport is best characterized in giant algal cells, but the situation may well be similar in higher plants. In Nitella translucens an ouabain-sensitive ATP-dependent sodium-potassium exchange pump at the plasmalemma maintains the high K/Na of the cell, and the high internal osmotic pressure is achieved by net salt uptake by a (chloride + cations) pump, also at the plasmalemma. The linkage between chloride and cations seems more likely to be chemical than electrogenic. This pump may be energized by a membrane redox system, but is not ATP-powered. The mechanism for initial entry of chloride to the cell seems also to control the distribution of tracer chloride between cytoplasm and vacuole, since the two processes of entry and transfer to the vacuole are very closely linked. The kinetics of vacuolar transfer are consistent with a pinocytotic entry of salt at the plasmalemma, fusion ofpinocytotic vesicles with the endoplasmic reticulum, from which new vacuole is formed. The process of discharge to the vacuole seems to be quantized, but the mechanism and significance of this observation are not understood.

scholarly journals Monoclonal antibody to intermediate filament antigen cross-reacts with higher plant cells.

1985 ◽  
Vol 100 (5) ◽  
pp. 1793-1798 ◽  
Author(s):  
P J Dawson ◽  
J S Hulme ◽  
C W Lloyd
Keyword(s):  
Monoclonal Antibody ◽  
Intermediate Filament ◽  
Higher Plants ◽  
Plant Cells ◽  
Heterologous Proteins ◽  
Root Tips ◽  
Suspension Cells ◽  
Higher Plant ◽  
Meristematic Cells ◽  
Carrot Protoplasts

The monoclonal antibody (anti-IFA) raised (Pruss et al., 1981, Cell 27:419-428) against an intermediate filament antigen, which is widespread throughout phylogeny, has been shown here to cross-react with higher plants. On immunoblotting, anti-IFA cross-reacted with proteins in homogenates of carrot suspension cells and of meristematic cells from onion root tips. A 50-kD cross-reactive protein was enriched in a fraction that consisted of detergent-insoluble bundles of 7-nm fibrils from carrot protoplasts (Powell et al., 1982, J. Cell Sci. 56:319-335). By use of indirect immunofluorescence, anti-IFA stained formaldehyde-fixed onion meristematic cells and carrot protoplasts in patterns approximating those obtained with monoclonal anti-tubulins. That anti-IFA was not recognizing plant tubulins was established by use of immunoblots of two-dimensional gels on which the proteins that comprised isolated fibrillar bundles and taxol-purified carrot tubulins had been separated. The two groups of proteins had different positional coordinates: anti-IFA recognized the fibrillar bundle proteins, and anti-tubulins recognized plant microtubule proteins with no cross-reaction to the heterologous proteins. Likewise, formaldehyde-fixed taxol microtubules from carrot cells could be stained with anti-tubulin but not with anti-IFA. It is concluded that an epitope common to intermediate filaments from animals co-distributes with microtubules in higher plant cells.

scholarly journals Putrescine metabolism in pea seedligs

2015 ◽  
Vol 40 (1) ◽  
pp. 197-207 ◽  
Author(s):  
B. Wielgat ◽  
K. Kleczkowski
Keyword(s):  
Higher Plants ◽  
Plant Cells ◽  
Aminobutyric Acid ◽  
Ornithine Carbamoyltransferase ◽  
Pea Seedlings ◽  
Oscillatory Mechanism

The effect of putrescine (Putr.) and N-carbamoylputrescine (N-CPutr.) fed to excised pea seedlings was studied. Contrary to great toxicity of higher than 0.5% Putr., N-CPutr. even at higher concentration was not toxic for the plants. The detoxication of plant cells by carbamoylation of Putr. was postulated. No differences were found in ornithine carbamoyltransferase (EC 2.1.3.3.) activity between plants fed with Putr. or N-CPutr. The most label from <sup>14</sup>C-putrescine was found in γ-aminobutyric acid. No labeled N-CPutr. was detected. The "oscillatory" mechanism of N-CPutr. synthesis in higher plants was postulated.

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