Effects of the Herbicide 2,4,5-T on the Incorporation of 14C-Thymidine, 3H-Uridine and 3H-L-Leucine into L 929 Cells

Abstract: A rapid inhibition of the incorporation of ³H-L-leucine, ³H-uridine and ¹⁴C-thymidine into the macromolecular fraction of L 929 cells was found when 2.25 mM 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) was added to the incubation medium. The reduced incorporation of ³H-uridine and ¹⁴C-thymidine could be explained by an inhibitory effect of 2,4,5-T on the uptake of these compounds into the acid-soluble precursor pool, whereas a direct effect on protein synthesis was indicated. Kinetic analysis of the uptake of uridine into the acid-soluble pool indicated that 2,4,5-T inhibited the facilitated transport of this nucleoside into the cell. The overall results are interpreted as indicating that 2,4,5-T induced alterations in the permeability of the cellular plasma membrane.