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Mechanisms of cobalt uptake in plants: 60 CO uptake and distribution in Chara
Author(s) -
Liu J.,
Reid R. J.,
Smith F. A.
Publication year - 1998
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.1998.1040309.x
Subject(s) - chara , vacuole , cobalt , cytoplasm , divalent , cell wall , intracellular , chemistry , biophysics , desorption , membrane , nuclear chemistry , biochemistry , adsorption , inorganic chemistry , biology , botany , organic chemistry
The mechanism of cobalt uptake was investigated using cells of the giant alga Chara corallina in which it is possible to resolve separately uptake by the cell wall and actual influx across the cell membrane. The absorption of 60 Co by Chara cells appeared to saturate within 2 h, but this was mainly due to rapid uptake into the cell wall which accounted for 87–92% of the total activity. Even after prolonged desorption most of the cell‐associated 60 Co was found on the cell wall. The intracellular distribution of absorbed 60 Co was investigated by fractionating the cell into cytoplasm and vacuole. It was shown that 60 Co influx to the vacuole occurs simultaneously with influx to the cytoplasm. The transported species appears to be Co 2+ rather than the less charged Co(OH) + or Co(OH) 2 . 60 Co influx is pH dependent (optimum pH 7–9), and is sensitive to some other divalent metals. Influx from solutions containing 1 µ M 60 Co was inhibited by 5 µ M Cd 2+ , Cu 2+ , and Zn 2+ , but Mn 2+ and Ni 2+ had no significant effect. The sensitivity of Co uptake to N ‐ethyl maleimide (NEM) and cysteine suggests that the transport system involves direct binding of CO 2+ to ‐SH groups.