ISSN:
1432-072X
Keywords:
Acid resistance
;
Dunaliella acidophila
;
membrane transport
;
membrane potential
;
Plasma membrane
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract A method was developed to determine electrical potential differences across the plasma membrane of the microalga Dunaliella by means of potential-sensitive microelectrodes. Special emphasis was put on the measurement of the membrane potential in the acidophilic Dunaliella acidophila (optimal growth at pH 1.0), but neutrophilic, halotolerant Dunaliella species were used as reference systems. For Dunaliella acidophila positive membrane potentials (cytoplasma relative to the medium), ranging from +30 to +65mV were measured. Illumination caused a decrease of the positive potential by about 10 mV. The ATPase inhibitor omeprazole caused an increase of the positive membrane potential ranging from +60 to +100 mV, whereas the ionophore gramicidin caused a decrease of the MP to +10 to +30 mV. The salt tolerant, neutrophilic Dunaliella parva and Dunaliella bardawil exhibited negative membrane potentials in the order of -40 to -60mV, and light caused a hyperpolarization of about 10 mV. A negative membrane potential was measured also in D. acidophila cells transferred to pH 7.0. The physiological significance of a positive membrane potential for acidophilic algae is discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00245364
Permalink