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Mr. Vilmantas Pupkis
Department of Neurobiology and Biophysics, Institute of Biosciences, Life Sciences Center, Vilnius University

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0 Biophysics
0 Patch Clamp
0 Plant Physiology
0 Ion Channel
0 Plant electrophysiology

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Journal article
Published: 29 March 2021 in Plants
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Inhibitors of human two-pore channels (TPC1 and TPC2), i.e., verapamil, tetrandrine, and NED-19, are promising medicines used in treatment of serious diseases. In the present study, the impact of these substances on action potentials (APs) and vacuolar channel activity was examined in the aquatic characean algae Nitellopsis obtusa and in the terrestrial liverwort Marchantia polymorpha. In both plant species, verapamil (20–300 µM) caused reduction of AP amplitudes, indicating impaired Ca2+ transport. In N. obtusa, it depolarized the AP excitation threshold and resting potential and prolonged AP duration. In isolated vacuoles of M. polymorpha, verapamil caused a reduction of the open probability of slow vacuolar SV/TPC channels but had almost no effect on K+ channels in the tonoplast of N. obtusa. In both species, tetrandrine (20–100 µM) evoked a pleiotropic effect: reduction of resting potential and AP amplitudes and prolongation of AP repolarization phases, especially in M. polymorpha, but it did not alter vacuolar SV/TPC activity. NED-19 (75 µM) caused both specific and unspecific effects on N. obtusa APs. In M. polymorpha, NED-19 increased the duration of repolarization. However, no inhibition of SV/TPC channels was observed in Marchantia vacuoles, but an increase in open probability and channel flickering. The results indicate an effect on Ca2+ -permeable channels governing plant excitation.

ACS Style

Mateusz Koselski; Vilmantas Pupkis; Kenji Hashimoto; Indre Lapeikaite; Agnieszka Hanaka; Piotr Wasko; Egle Plukaite; Kazuyuki Kuchitsu; Vilma Kisnieriene; Kazimierz Trebacz. Impact of Mammalian Two-Pore Channel Inhibitors on Long-Distance Electrical Signals in the Characean Macroalga Nitellopsis obtusa and the Early Terrestrial Liverwort Marchantia polymorpha. Plants 2021, 10, 647 .

AMA Style

Mateusz Koselski, Vilmantas Pupkis, Kenji Hashimoto, Indre Lapeikaite, Agnieszka Hanaka, Piotr Wasko, Egle Plukaite, Kazuyuki Kuchitsu, Vilma Kisnieriene, Kazimierz Trebacz. Impact of Mammalian Two-Pore Channel Inhibitors on Long-Distance Electrical Signals in the Characean Macroalga Nitellopsis obtusa and the Early Terrestrial Liverwort Marchantia polymorpha. Plants. 2021; 10 (4):647.

Chicago/Turabian Style

Mateusz Koselski; Vilmantas Pupkis; Kenji Hashimoto; Indre Lapeikaite; Agnieszka Hanaka; Piotr Wasko; Egle Plukaite; Kazuyuki Kuchitsu; Vilma Kisnieriene; Kazimierz Trebacz. 2021. "Impact of Mammalian Two-Pore Channel Inhibitors on Long-Distance Electrical Signals in the Characean Macroalga Nitellopsis obtusa and the Early Terrestrial Liverwort Marchantia polymorpha." Plants 10, no. 4: 647.

Journal article
Published: 24 November 2020 in The Biophysicist
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Using giant characeaen algae Nitellopsis obtusa in laboratory exercises is proposed to familiarize students with basic concepts of electrophysiology and provide some simple hands-on practice. The described concept experiments present extracellular registration of action potentials (APs) and investigation of cytoplasmic streaming properties. Students are expected to register the propagation velocity of APs (found to be 3.4 ± 1.5 cm/s in N. obtusa), as well as the velocity of cytoplasmic streaming (66.7 ± 9 μm/s). Proposed exercises also concern recovery dynamics of cytoplasmic streaming after a stimulation (recovery time constant τ = 3.7 ± 2.1 min) as well as investigation of an effect of various chemicals (e.g., KCl) on all selected parameters. The experiments endorse characeaen algae as a model system to be routinely explored in education of biophysics and bioelectrical phenomena of the cell.

ACS Style

Vilmantas Pupkis; Rokas Buisas; Indre Lapeikaite; Vilma Kisnieriene. Using Plant Cells of Nitellopsis obtusa for Biophysical Education. The Biophysicist 2020, 2, 18 -29.

AMA Style

Vilmantas Pupkis, Rokas Buisas, Indre Lapeikaite, Vilma Kisnieriene. Using Plant Cells of Nitellopsis obtusa for Biophysical Education. The Biophysicist. 2020; 2 (1):18-29.

Chicago/Turabian Style

Vilmantas Pupkis; Rokas Buisas; Indre Lapeikaite; Vilma Kisnieriene. 2020. "Using Plant Cells of Nitellopsis obtusa for Biophysical Education." The Biophysicist 2, no. 1: 18-29.

Research article
Published: 01 January 2020 in Functional Plant Biology
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The effect of glutamate and N-methyl-d-aspartate (NMDA) on electrical signalling – action potentials (AP) and excitation current transients – was studied in intact macrophyte Nitellopsis obtusa (Characeaen) internodal cell. Intracellular glass electrode recordings of single cell in current clamp and two-electrode voltage clamp modes indicate that glutamate (Glu, 0.1–1.0 mM) and NMDA (0.01–1.0 mM) increase electrically induced AP amplitude by hyperpolarising excitation threshold potential (Eth) and prolong AP fast repolarisation phase. Amplitude of Cl– current transient, as well as its activation and inactivation durations were also increased. Both Glu and NMDA act in a dose-dependent manner. The effect of NMDA exceeds that of Glu. Ionotropic glutamate receptor inhibitors AP-5 (NMDA-type receptors) and DNQX (AMPA/Kainate-type) have no effect on Nitellopsis cell electrical signalling per se, yet robustly inhibit excitatory effect of NMDA. This study reinforces NMDA as an active component in glutamatergic signalling at least in some plants and stresses the elaborate fine-tuning of electrical signalling.

ACS Style

Indre Lapeikaite; Vilmantas Pupkis; Vladas Neniskis; Osvaldas Ruksenas; Vilma Kisnieriene. Glutamate and NMDA affect cell excitability and action potential dynamics of single cell of macrophyte Nitellopsis obtusa. Functional Plant Biology 2020, 47, 1032 -1040.

AMA Style

Indre Lapeikaite, Vilmantas Pupkis, Vladas Neniskis, Osvaldas Ruksenas, Vilma Kisnieriene. Glutamate and NMDA affect cell excitability and action potential dynamics of single cell of macrophyte Nitellopsis obtusa. Functional Plant Biology. 2020; 47 (12):1032-1040.

Chicago/Turabian Style

Indre Lapeikaite; Vilmantas Pupkis; Vladas Neniskis; Osvaldas Ruksenas; Vilma Kisnieriene. 2020. "Glutamate and NMDA affect cell excitability and action potential dynamics of single cell of macrophyte Nitellopsis obtusa." Functional Plant Biology 47, no. 12: 1032-1040.

Original research article
Published: 18 February 2019 in Frontiers in Plant Science
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Action potentials (AP) of characean cells were the first electrical transients identified in plants. APs provide information about plethora of environmental cues. Salinity stress is critical for plants and impacts on excitability. The AP of brackish Characeae Nitellopsis obtusa, obtained in artificial pond water (APW) and under osmotic stress of 90 or 180 mM sorbitol APW or saline stress of 50 or 100 mM NaCl APW, were simulated by the Thiel-Beilby model (Beilby and Al Khazaaly, 2016). The model is based on a paradigm from animal systems, featuring the second messenger inositol 1,4,5-triphosphate (IP3) mediating the opening of Ca2+ channels on internal stores. In plants the IP3 receptors have not been identified, so other second messengers might translate the threshold plasma membrane depolarization to Ca2+ release. The increased Ca2+ concentration in the cytoplasm activates Cl− channels, which lead to the depolarizing phase of the AP. The repolarization to normal resting potential difference (PD) results from the Ca2+ being re-sequestered by the Ca2+ pumps, the closure of the Cl− channels, efflux of K+ through the depolarization-activated outward rectifier channels and the continuing activity of the proton pump. The Nitellopsis AP form is longer in APW compared to that of Chara, with more gradual repolarization. The tonoplast component of the AP is larger than that in Chara australis. The plasma membrane AP is prolonged by the exposure to saline to a “rectangular” shape, similar to that in Chara. However, the changes are more gradual, allowing more insight into the mechanism of the process. It is possible that the cells recover the original AP form after prolonged exposure to brackish conditions. Some cells experience tonoplast APs only. As in Chara, the proton pump is transiently inhibited by the high cytoplasmic Ca2+ and gradually declines in saline media. However, if the cells are very hyperpolarized at the start of the experiment, the pump inhibition both by the AP and by the saline medium is mitigated. The model parameters and their changes with salinity are comparable to those in Chara.

ACS Style

Vilma Kisnieriene; Indre Lapeikaite; Vilmantas Pupkis; Mary Jane Beilby. Modeling the Action Potential in Characeae Nitellopsis obtusa: Effect of Saline Stress. Frontiers in Plant Science 2019, 10, 1 .

AMA Style

Vilma Kisnieriene, Indre Lapeikaite, Vilmantas Pupkis, Mary Jane Beilby. Modeling the Action Potential in Characeae Nitellopsis obtusa: Effect of Saline Stress. Frontiers in Plant Science. 2019; 10 ():1.

Chicago/Turabian Style

Vilma Kisnieriene; Indre Lapeikaite; Vilmantas Pupkis; Mary Jane Beilby. 2019. "Modeling the Action Potential in Characeae Nitellopsis obtusa: Effect of Saline Stress." Frontiers in Plant Science 10, no. : 1.

Original article
Published: 05 October 2018 in Protoplasma
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Effect of amino acid l-asparagine on electrical signalling of single Nitellopsis obtusa (Characeaen) cell was investigated using glass-microelectrode technique in current-clamp and voltage-clamp modes. Cell exposure for 30 min to 0.1 mM and 1 mM of asparagine resulted in changes of electrically stimulated action potential (AP) parameters in comparison to standard conditions. Results indicate that asparagine acts in dose-dependent manner: increases AP amplitude by hyperpolarizing AP threshold potential (Eth), prolongs action potential repolarization, increases maximum Cl− efflux amplitude along with the increase of activation and inactivation durations. Presented findings provide new aspects of exogenous amino acids’ effect on plants’ electrical signalling with emphasis on separate single plant cell excitability and AP characteristics.

ACS Style

Indre Lapeikaite; Ugne Dragunaite; Vilmantas Pupkis; Osvaldas Ruksenas; Vilma Kisnieriene. Asparagine alters action potential parameters in single plant cell. Protoplasma 2018, 256, 511 -519.

AMA Style

Indre Lapeikaite, Ugne Dragunaite, Vilmantas Pupkis, Osvaldas Ruksenas, Vilma Kisnieriene. Asparagine alters action potential parameters in single plant cell. Protoplasma. 2018; 256 (2):511-519.

Chicago/Turabian Style

Indre Lapeikaite; Ugne Dragunaite; Vilmantas Pupkis; Osvaldas Ruksenas; Vilma Kisnieriene. 2018. "Asparagine alters action potential parameters in single plant cell." Protoplasma 256, no. 2: 511-519.

Website
Published: 03 September 2018 in Neurotransmitters in Plant Life
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Intrinsic properties of Characean macroalgae and explicit electrical signaling properties provide a model system for complex investigation of instantaneous effects of neurotransmitters on plant bioelectrical signals in vivo. General characteristics of Characean physiology and electrical signaling properties are discussed, specifically focusing on those representing effects of neurotransmitters acetylcholine, dopamine, gamma-aminobutyric acid, and melatonin on single plant cells. Diverse experimental approaches and real-time electrical measurements on intact cells and cytoplasmic droplets after exposure to neurotransmitters are presented. Membrane potential (MP) alterations and action potential (AP) patterns represent the cell responses. The electrical properties of tonoplast ion channels can be studied using cytoplasmic droplets by patch clamping. Investigation of electrical cell-to-cell communication revealed evidence on the electrical signal transduction through plasmodesmata in Characean macroalgae.

ACS Style

Vilma Kisnieriene; Indre Lapeikaite; Vilmantas Pupkis. Neurotransmitters in Characean Electrical Signaling. Neurotransmitters in Plant Life 2018, 181 -200.

AMA Style

Vilma Kisnieriene, Indre Lapeikaite, Vilmantas Pupkis. Neurotransmitters in Characean Electrical Signaling. Neurotransmitters in Plant Life. 2018; ():181-200.

Chicago/Turabian Style

Vilma Kisnieriene; Indre Lapeikaite; Vilmantas Pupkis. 2018. "Neurotransmitters in Characean Electrical Signaling." Neurotransmitters in Plant Life , no. : 181-200.

Research article
Published: 01 January 2018 in Functional Plant Biology
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The Nitellopsis obtusa (N.A.Desvaux) J.Groves cell provides a model system for complex investigation of instantaneous effects of various biologically active compounds (BC) on the generation of plant bioelectrical signals in vivo. Experimental evidence using multiple electrical signals as biomarkers of the effects of BC (acetylcholine, asparagine, glutamate, nicotine, aluminium, nickel and cadmium ions) is provided. The effect of BC on membrane transport systems involved in the cell excitability were tested by current clamp, voltage clamp and patch clamp methods. Membrane potential (MP) alterations and action potential (AP) patterns in response to BC were shown to represent the cell state. High discretisation frequency allows precise, high time resolution analysis of real-time processes measuring changes in excitation threshold, AP amplitude and velocity of repolarisation values after application of BC indicating the effect on ion channels involved in AP generation. Application of voltage clamp revealed that changes in AP peak value were caused not only by increment in averaged maximum amplitude of the Cl– current, but in prolonged Cl– channels’ opening time also. The cytoplasmic droplet can serve as a model system in which the effects of BC on single tonoplast ion channel can be studied by patch clamping. Investigation of electrical cell-to-cell communication revealed evidence on the electrical signal transduction through plasmodesmata.

ACS Style

Vilma Kisnieriene; Indre Lapeikaite; Vilmantas Pupkis. Electrical signalling in Nitellopsis obtusa: potential biomarkers of biologically active compounds. Functional Plant Biology 2018, 45, 132 -142.

AMA Style

Vilma Kisnieriene, Indre Lapeikaite, Vilmantas Pupkis. Electrical signalling in Nitellopsis obtusa: potential biomarkers of biologically active compounds. Functional Plant Biology. 2018; 45 (2):132-142.

Chicago/Turabian Style

Vilma Kisnieriene; Indre Lapeikaite; Vilmantas Pupkis. 2018. "Electrical signalling in Nitellopsis obtusa: potential biomarkers of biologically active compounds." Functional Plant Biology 45, no. 2: 132-142.