Nitrate Transport intoChara corallinaCells using36C1O3as an Analogue for Nitrate
- 1 September 1984
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of Experimental Botany
- Vol. 35 (9) , 1299-1308
- https://doi.org/10.1093/jxb/35.9.1299
Abstract
36C1O3/NO3 influx into Chara cells was found to be sensitive to pHo and a maximum was found at pHo = 4.5. By contrast 14C methylamine influx into Chara showed a maximum at pHo = 8.5, and at this pHo influx rates were about 150 times higher than rates of 36C1O3/NO3 influx. However, at pHo = 4.5, 36C1O3/NO3 influx rates were, in some cases, comparable with rates of 14C methylamine influx. 36C1O3/NO3 influx into Chara cells was stimulated by Rb +, K+, Na +, and NH4+, but not by Cs+ or Li +. NO3 and Cl reduced 14C methylamine influx into Chara by ∼ 30%. NH4+ caused very considerable inhibition of 14C methylamine influx into Chara, but had no effect on 36C1O3/NO3 influx in the presence of K +. Net NO3 uptake into Chara was completely prevented by NH4+ even at relatively low NH4+ concentrations (25 mmol m −3). This latter effect was reversed by diethylstilbestrol (DES). Evidence is presented for the stimulation of NO3 efflux by NH4+ as the mechanism responsible for the immediate effects of NH4+ on net NO3 uptake into Chara cells.Keywords
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