ISSN:
1615-6102
Keywords:
Chemoreception
;
Chemotaxis
;
Physarum polycephalum
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary In the plasmodium ofPhysarum polycephalum application of various monovalent cation salts elicited either a depolarization or a hyperpolarization of the membrane potential. The hyperpolarization was restricted to phosphates and bicarbonates of large cations (Na+, Li+, NMe4 +, NEt4 +). More than 50 other combinations of cations (K+, Rb+, Cs+, NH4 +) and anions (Cl−, NO3 −, SO4 2−, acetate, lactate, citrate, etc.) induced the depolarization. In both cases the magnitude of the deflection in membrane potential (Δϕ) varied linearly with logarithm of concentration above the threshold Cth (∼10−4 M for all monovalent cation salts examined) according to the following equation: Δϕ=± R log (C/Cth). The value of R was 10–15 mV, and plus and minus signs correspond to depolarization and hyperpolarization, respectively. Depolarizing and hyperpolarizing agents competed with each other and exhibited a sharp transition between the two states of the membrane which were characterized by — R and R in the above equation or displayed a strong hysteresis, depending on which agents had first been applied to the plasmodial membrane. This transition in the membrane potential corresponded to the transition between positive and negative taxis at the behavioral level.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01290773
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