Plasmalemma Transport of HCO3−and OH−inChara corallina: Non-antiporter Systems
- 1 February 1976
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of Experimental Botany
- Vol. 27 (1) , 19-31
- https://doi.org/10.1093/jxb/27.1.19
Abstract
An experimental system was designed to test the obligate coupling between HCO3− and OH− fluxes (i. e. a ‘Mitchell-type’ antiporter) proposed by Lucas and Smith (1973). The results of these experiments demonstrated categorically that the OH− efflux process can function in the absence of exogenous HCO3− at the actual OH− efflux site. Hence, the obligate coupling hypothesis is invalid. It is proposed that HCO3− and OH− are transported across the plasmalemma ‘independently’, on quite distinct carriers. It is possible, therefore, that these fluxes contribute towards determining the electrical properties of this membrane when the bathing solution pH value is ≧6.5. It was also found that HCO3− can be transported across the dark segment of a partly illuminated cell. The observed rates were always much less than those obtained in the illuminated cell segment. The significance of this result is discussed.Keywords
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