Patterns of protein synthesis in livers of Xenopus laevis during metamorphosis: Effects of estrogen in normal and thyrostatic animals

Abstract

Two-dimensional gel electrophoresis has been used to analyse protein synthesis in the livers of Xenopus laevis larvae during metamorphosis. The patterns found at different developmental stages have been characterised and compared to those found in developmentally static tadpoles and estrogen-treated tadpoles. The results suggest that the majority of proteins synthesized by the larval liver during metamorphosis can be divided equally into three main categories: those which are synthesized continuously, those whose synthesis is lost, and those whose synthesis is gained during development. The synthesis of proteins tends to be lost earlier in metamorphosis than it is gained. The pattern of liver protein synthesis in thyrostatic animals is not characteristic of any single stage of normal development, and displays features characteristic of many different stages. About half the changes in protein synthesis which occur during normal metamorphosis are dependent upon it. All the stages examined are responsive to estrogen, and each has a characteristic response. Half of the estrogen-induced changes in protein synthesis are independent of metamorphosis, while the other half require metamorphosis.