Effects of Inhibitors of Protein and Nucleic Acid Synthesis on the Development of Ion Uptake Mechanisms in Beetroot Slices (Beta vulgaris)

Abstract

AbstractMechanisms for the uptake of K+, Na+ and Cl‐ develop sequentially in thin slices of beetroot tissue washed under aerobic conditions. Actinomycin D inhibited or prevented the development of K+, Na+ and Cl‐ uptake mechanisms when added to freshly cut slices, but had no effect on net ion uptake when added after the development of the ion uptake mechanisms. The use of puromycin as a specific inhibitor of protein synthesis was unsatisfactory as it caused leakage of pigments and excessive loss of ions from the disks.Cycloheximide prevented the development of ion uptake mechanisms when added at the start of the experiment, but when added after the development of ion uptake mechanisms its inhibitory effect did not become apparent until after a certain time interval which varied from 3 hours for Cl‐ to 25 hours for K+ uptake in the same experiment. p‐Fluorophenylalanine caused an appreciable shortening of the time required for the development of Na+ and K+ uptake capabilities, while it completely prevented the development of a Cl‐ uptake mechanism. p‐Fluorophenylalanine‐induced early uptake of Na+ and K+, however, was followed by periods of net leakage of these ions.It is suggested that the development of ion uptake mechanisms depends on the production of m‐RNA, which appears to be relatively stable after its synthesis. The synthesis and decay characteristics of specific proteins required for the ion uptake mechanisms appear to differ for each ion species.