Pj. Mautsoe et Rp. Beckett, A PRELIMINARY-STUDY OF THE FACTORS AFFECTING THE KINETICS OF CADMIUM UPTAKE BY THE LIVERWORT DUMORTIERA-HIRSUTA, South African journal of botany, 62(6), 1996, pp. 332-336
Intra- and extracellular Cd uptakes by the liverwort Dumortiera hirsut
a (SW) Nees. were investigated. While intracellular Cd uptake was line
ar with time and displayed Michaelis-Menten kinetics, extracellular Cd
uptake displayed saturation kinetics. K-m and V-max were 149 +/- 19 m
u M and 11.0 +/- 0.8 mu mol g(-1) h(-1) respectively. Intra-, and to a
lesser extent, extracellular uptakes were temperature dependent. Ligh
t stimulated intracellular Cd uptake by c. 15%. The rate of intracellu
lar Cd uptake in the dark was probably not directly linked to the supp
ly of respirable reserves, because storage for 20 days in the dark did
not affect it. incubating the liverwort concurrently with Cd and equi
molar concentrations of Ca, Mg or Zn all reduced intra- and extracellu
lar Cd uptake, which suggests that the Cd uptake systems had low speci
ficity. Pretreatment of plants with 80 mM KNO3 stimulated Cd uptake, a
pparently because the K removed potentially competing ions from the ce
ll waif. Results are compared with similar investigations on other cry
ptogams.