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PHOSPHATE TRANSPORT IN HYDRODICTYON AFRICANUM
Author(s) -
Raven J. A.
Publication year - 1974
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1974.tb02119.x
Subject(s) - phosphate , polyphosphate , vacuole , ion transporter , chemistry , chloride , efflux , biophysics , inorganic chemistry , cytoplasm , biochemistry , biology , membrane , organic chemistry
SUMMARY The transport and distribution of phosphate in Hydrodictyon africanum is reported, and discussed in relation to phosphate transport in other green algae and chloride transport in Hydrodictyon. The inorganic phosphate concentration in both vacuole and cytoplasm is 1–2 mM; the cytoplasm also contains 35 mM of phosphate as organic and polyphosphate, which are absent from the vacuole. Phosphate influx from 0.1 mM phosphate at pH 6.5 was much greater than the efflux, and was more stimulated by light and inhibited by low temperature than was the efflux. The phosphate influx is, on electrochemical criteria, active. The influx at the tonoplast was much higher than that at the plasmalemma. Na stimulated phosphate influx more than did K, in agreement with results for other green algae but in contrast to monovalent cation effects on active Cl influx. Both phosphate and chloride influxes show a simple hyperbolic relationship between anion concentration and influx, in the concentration range tested, but the kinetics for the two ions show different responses to changes in irradiance and Na concentration. pH effects on the influxes are also reported. The passive permeability of the plasmalemma to H 2 PO ‐ 4 is similar to that to Cl ‐ .