Electrical signalling in Nitellopsis obtusa: potential biomarkers of biologically active compounds

Abstract

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 Clcurrent, but in prolonged Clchannels' 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.

Illumination/Darkness-Induced Changes in Leaf Surface Potential Linked With Kinetics of Ion Fluxes

“…Potassium ions play an important role in plant electrical activity. In the study of the mechanism of action potential generation, the repolarization process is initiated when the voltage-dependent outward rectifier potassium ion channels are opened (Tsutsui et al, 1986; Koselski et al, 2017; Stolarz and Dziubinska, 2017; Kisnieriene et al, 2018). Under periodic illumination, changes in K + fluxes were unique because different types of cells show different polarization states.…”

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

“…Mature giant algae Nitellopsis obtusa (N.A. Desvaux) J. Groves were collected from Lithuanian lakes during autumn months and maintained in aquariums as described in [ 53 ]. Prior to the experiments, the internodal cells (second or third below the tip) were separated from neighboring internodal cells and kept at least overnight in buffered artificial pond water (APW) in daylight conditions.…”

Using Plant Cells of Nitellopsis obtusa for Biophysical Education

“…Ca 2þ ions in the cytoplasm activate Cl À channels, allowing Cl À efflux and further depolarization of the plasma membrane. Depolarization itself and Ca 2þ ions then activate K þ channels, thus allowing K þ ion efflux and membrane repolarization to its resting potential, which is completed because of the activity of an H þ pump, as well (13)(14)(15).…”