FATE OF RETICULOCYTE RIBOSOMES DURING IN VIVO MATURATION

Changes in the distribution of ribosomes in rabbit reticulocytes have been studied during maturation in vivo. 32P was given intravenously to label the ribonucleic acid of these cells and the distribution of the isotope in ribosomes was followed with time. Both the percentage of ribosomes existing as polysomes and the aggregate size distribution of polysomes remained constant during the maturation of the reticulocytes. These findings are particularly noteworthy in view of the observed loss in the total content of ribosomes. The results of this study, employing an autologous system for the maturation of cells in vivo, are in agreement with the results of previous studies from this laboratory in which a heterologous system was employed. These investigations suggest that, once formed, each individual polysome aggregate continues to function unchanged until its ultimate destruction during the process of reticulocyte maturation. If 80S monomers are produced during the destruction of polysomes they in turn are short lived since they cannot be detected as an increased percentage of monosomes with increased cell age. © 1969, American Chemical Society. All rights reserved.