CYTOCHEMICAL STUDIES OF NUCLEIC ACIDS AND PROTEINS IN ERYTHROCYTIC DEVELOPMENT

Abstract

Microphotometric measurements of various stages of red blood cell formation indicated a gradual loss of cytoplasmic RNA throughout the process. In later stages both total protein and hemoglobin revealed a concomitant increase. Autoradiographic analysis of RNA synthesis utilizing tritiated cytidine showed no incorporation after the basophilic erythroblast stage. DNA measurements revealed a bimodal distribution into 2C, 4C, and intermediate values in all stages except the late normoblast. The latter contained the 2C amount of DNA, while extruded nuclei revealed a decrease in DNA. It was concluded that: (1): a stable informational RNA complex is formed only in the earliest developmental phases and is retained throughout the process; (2) the loss of RNA in early stages is chiefly limited to an "inactive" riboso-mal fraction while the "active" fraction is retained; and (3) the nuclei serve both as the origin of the stable messenger and as a means for proliferation of the system.