“Action potentials” in NEUROSPORA CRASSA, a mycelial fungus

Slayman, Clifford L.; Long, W. Scott; Gradmann, Dietrich

doi:10.1016/0005-2736(76)90138-3

Cited by 100 publications

(63 citation statements)

References 29 publications

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“…Under these conditions, NcTOKA activation could play a role in membrane potential stabilization and prevent deleterious depolarization of the membrane. Furthermore, Neurospora plasma membrane potential has been shown to oscillate, which can result in membrane potential depolarizations to values positive of E K (35). Although the physiological relevance of these oscillations is unclear, NcTOKA could play a role in the propagation of the oscillation, similar to the role of K ϩ channels in the propagation of an action potential in "excitable" cells.…”

Section: Discussionmentioning

confidence: 99%

TOK Homologue in Neurospora crassa : First Cloning and Functional Characterization of an Ion Channel in a Filamentous Fungus

Roberts

2003

Eukaryot Cell

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In contrast to animal and plant cells, very little is known of ion channel function in fungal physiology. The life cycle of most fungi depends on the "filamentous" polarized growth of hyphal cells; however, no ion channels have been cloned from filamentous fungi and comparatively few preliminary recordings of ion channel activity have been made. In an attempt to gain an insight into the role of ion channels in fungal hyphal physiology, a homolog of the yeast K ؉ channel (ScTOK1)

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Section: Discussionmentioning

confidence: 99%

TOK Homologue in Neurospora crassa : First Cloning and Functional Characterization of an Ion Channel in a Filamentous Fungus

Roberts

2003

Eukaryot Cell

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“…This slow time course is due to the existence of the large capacity Cv, which has been analogized with the ATP pool 1-3]. Comparable slow action potentials have been found in the fungus Neurospora [19] where, however, no capacity in the range of mFcm -a could be demonstrated. On the other hand, these action potentials in Neurospora are the only example besides the action potentials of Acetabularia, which can be interpreted as arising in the pathway of the electrogenic pump.…”

Section: Operation Of the "~ Action Potentialmentioning

confidence: 99%

“…Besides the classical preparations of nerves and muscles, plants such as Mimosa and Oionaea (for review see [14]) or Nitella (reviewed in [10]) and many others, even fungi (Neurospora [19]), show action potentials. However, the mechanisms in the particular systems seem to differ, not only in the time base (animal cells in the range of msec, most plants in sec and Neurospora as well as Acetabularia in min), but also in the ions involved.…”

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confidence: 99%

“Metabolic” action potentials inAcetabularia

Gradmann

1976

J. Membrain Biol.

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The transient depolarizations in Acetabularia which fulfill the essential criteria of an action potential (all-or-none characteristics, triggering by depolarization, propagation, etc.) are investigated. These action potentials are analyzed by conductance measurements and voltage clamp experiments on the basis of the analog circuit of the membrane (Gradmann, D. 1975, J. Membrane Biol. 25:183). It is concluded that these action potentials do not arise by permeability changes of the passive diffusion channels, but by the active pathway of the electrogenic pump, which consists of a voltage source EP of about --20 mV in series with two nonlinear conducting elements P1 and P2, the latter and EP being shunted by a large quasi capacity CP of some mF cm-2. The nonlinear current-voltage relationship of the carrier system (P1) is not changed during the action potential but has an effect on its time course. However, the elements P2 and CP, which probably reflect metabolic entities, are suggested to control the action potentials.

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“…The minimum elements of a proton pump, although nonlinear, lead only to monotone relaxation kinetics. However, by including the coupling of other ion-transport processes, such as those of potassium and calcium, to the proton pump, we find that such systems behave like a damped oscillator [which has been observed in experiments (12)]. With that property a reduction in dissipation is feasible.…”

Section: Introductionmentioning

confidence: 55%

“…We choose the class of proton pumps found in the plasma membrane of yeast cells (9)(10)(11), Neurospora (12,13), and higher plant cells (14). These proton pumps consist of a membrane-bound enzyme that catalyzes the processes in which ATP is hydrolyzed and protons are transported across the membrane against an electrochemical gradient.…”

Section: Introductionmentioning

confidence: 99%

Dependence of thermodynamic efficiency of proton pumps on frequency of oscillatory concentration of ATP.

Schell¹,

Kundu²,

Ross³

1987

Proc. Natl. Acad. Sci. U.S.A.

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In order to evaluate the utilization of variable ATP concentration produced by an oscillatory reaction (as in anaerobic glycolysis), we analyze the thermodynamic efficiency of power output of a cyclic, ATP-driven proton pump found in the plasma membrane of plant cells. The model used includes the coupling of potassium and calcium ion transport. Oscillations in the concentration of ATP can lead to either increases or decreases in efficiency compared to that at constant ATP concentration, with corresponding decreases and increases in dissipation in the irreversible processes of the proton pump, depending on the frequency of the oscillations. Variations of imposed frequencies induce, in the periodic response, variations of phase shifts between the components of the total membrane current, which consist of the pump's proton current and the currents of potassium and calcium ions. Increases in efficiency are attained when the phase shifts are such that maxima (or minima) in the proton pump current and membrane potential occur simultaneously.

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“Action potentials” in NEUROSPORA CRASSA, a mycelial fungus

Cited by 100 publications

References 29 publications

TOK Homologue in Neurospora crassa : First Cloning and Functional Characterization of an Ion Channel in a Filamentous Fungus

TOK Homologue in Neurospora crassa : First Cloning and Functional Characterization of an Ion Channel in a Filamentous Fungus

“Metabolic” action potentials inAcetabularia

Dependence of thermodynamic efficiency of proton pumps on frequency of oscillatory concentration of ATP.

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