Effect of insulin, prednisolone and diiodothyronine on 3H-uridine intake and localization in Tetrahymena.

Quantitative light and electron microscopic autoradiography demonstrated a dissimilar effect of insulin, prednisolone and diiodothyronine on the incorporation and localization of 3H-uridine in Tetrahymena. After treatment with insulin for 1 h, uridine was rapidly incorporated, and after initial accumulation in the cytoplasm its intracellular level tended to drop below the control. Total uridine incorporation was lower than in the control cells. In Tetrahymena treated with prednisolone or diiodothyronine, uridine incorporation was relatively slow, but the intracellular uridine level increased significantly over the control. Re-exposure to the hormone had no significant influence in the case of insulin, but altered the quantitative relations of uridine incorporation significantly in the case of the morphogenetic hormones prednisolone and T2.