caa a22 4500 477100589 CHVBK 20180405111540.0 cr unu---uuuuu 170330e19960101xx s 000 0 eng 10.1007/BF00197584 doi (NATIONALLICENCE)springer-10.1007/BF00197584 The mechanism of zinc uptake in plants [Elektronische Daten] Characterisation of the low-affinity system [Robert Reid, Justin Brookes, Mark Tester, F. Smith] The mechanism of zinc influx was investigated using giant algal cells (Chara corallina Klein ex Will.esk. R.D. Wood), in which it was possible to discriminate clearly between tracer zinc bound in the cell wall and actual uptake into the cell. It was shown that despite lengthy desorption, retention of zinc in slowly exchanging zinc pools in the cell wall can invalidate tracer influx measurements. A comparative study of zinc desorption from isolated cell walls of wheat (Triticum aestivum L.) roots indicated exchange characteristics similar to that of Chara. Fractionation of Chara internodal cells taken directly from cultures showed that most of the cell-associated zinc was in the cell walls. The cytoplasmic and vacuolar zinc concentrations were 56 mmol·m−3 and 32 mmol·m−3, respectively, for cells grown in a zinc concentration of 0.1 mmol·m−3. Influx of 65Zn in Chara was linear over several hours, with rapid transfer to the vacuole, but only slow efflux. Influx occurred in a biphasic manner, which was tentatively attributed to the operation of two separate transport systems, a high-affinity system which is saturated at 0.1 mmol·m−3 and a low-affinity system which showed a linear dependence on concentration up to at least 50 mmol·m−3. Only the low-affinity system was examined in detail. Influx through this system showed a strong dependence on external pH with an optimum around 7 and was also stimulated by cytoplasmic acidification. Influx was sensitive to metabolic inhibition, but not to blockers of Ca2+ and K+ channels. Other characteristics included a slight sensitivity to Mn2+ and Fe2+ but little sensitivity to high concentrations of K+ or Na+. Influx was independent of membrane potential difference in cells voltage-clamped at − 65 to − 300 mV. Springer-Verlag, 1996 Chara nationallicence Cell wall and zinc nationallicence Micronutrient nationallicence Triticum nationallicence Zinc uptake nationallicence APW : artificial pond water nationallicence CCCP : carbonylcyanide m-chlorophenylhydrazone nationallicence GFAAS : graphite furnace atomic absorption spectrometry nationallicence PD : potential difference nationallicence TEA : tetraethylammonium nationallicence Reid Robert Botany Department, University of Adelaide, 5005, Adelaide, S.A., Australia aut Brookes Justin Botany Department, University of Adelaide, 5005, Adelaide, S.A., Australia aut Tester Mark Department of Plant Sciences, University of Cambridge, Downing St., CB2 3EA, Cambridge, UK aut Smith F. Botany Department, University of Adelaide, 5005, Adelaide, S.A., Australia aut Planta Springer-Verlag 198/1(1996-01-01), 39-45 0032-0935 198:1<39 1996 198 425 https://doi.org/10.1007/BF00197584 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00197584 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Reid Robert Botany Department, University of Adelaide, 5005, Adelaide, S.A., Australia aut NATIONALLICENCE 700 1- Brookes Justin Botany Department, University of Adelaide, 5005, Adelaide, S.A., Australia aut NATIONALLICENCE 700 1- Tester Mark Department of Plant Sciences, University of Cambridge, Downing St., CB2 3EA, Cambridge, UK aut NATIONALLICENCE 700 1- Smith F. Botany Department, University of Adelaide, 5005, Adelaide, S.A., Australia aut NATIONALLICENCE 773 0- Planta Springer-Verlag 198/1(1996-01-01), 39-45 0032-0935 198:1<39 1996 198 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer