Uptake of 86Rb and K by Excised Maize Roots

Uptake of rb and k by excised maize roots.

Radioactive isotopes are valuable tools for investigating the uptake and transport of ions by biological material. Their use as tracers provide results that often can be obtained only by such a technique. The reliability of isotopes as tracers, however, is sometimes implicitly accepted. Although the pitfalls are widely known, they are often ignored. The hazards were emphasized for us in the use...

BOTANY: J. E. McCLARY SYNTHESIS OF THIAMIN BY EXCISED ROOTS OF MAIZE* BY J. EDWARD MCCLARY

Cadmium-induced sulfate uptake in maize roots.

The effect of cadmium (Cd) on high-affinity sulfate transport of maize (Zea mays) roots was studied and related to the changes in the levels of sulfate and nonprotein thiols during Cd-induced phytochelatin (PC) biosynthesis. Ten micromolar CdCl(2) in the nutrient solution induced a 100% increase in sulfate uptake by roots. This was not observed either for potassium or phosphate uptake, suggesti...

Inhibition of respiration and ion uptake by 2,3,5-triiodobenzoic Acid in excised barley roots.

The addition of 1 micromolar 2,3,5-triiodobenzoic acid (TIBA) to solutions containing KCl resulted in the inhibition of K and Cl uptake in excised barley roots. The effectiveness of TIBA as an inhibitor increased as the pH of the treatment solution decreased and approached the pK(a) of TIBA. A lag period of approximately 20 minutes existed prior to the onset of TIBA induced inhibition of ion up...

Inhibition of Ca2+ and Zn2+ Uptake by Mn2+ in Excised Rice Roots

The effects of varying concentrations of Mn2* on the absorption of divalent cations, viz., Ca2+ and Zn2+ from 2 concentrations were studied. Mn2+ at all concentrations tested were inhibitory to Ca2+ uptake from 0.1 and 5 mM CaCl2 . However, when Ca2+ uptake was measured at concentrations ranging from 0.05 to 10 mM CaCl2, MnCl2 only at high concentration of 5 mM, inhibited Ca ab­ sorption. Zn2+ ...