Biosynthesis of poly(A)-RNA and differentiation in chick erythrocytes

The rates of synthesis of poly(A)-containing RNA species in the nuclei of erythrocytes from 4- to 9-day-old chick embryos were determined by poly(T)-cellulose chromatography and were found to vary according to the developmental stages of the chick embryos. The rate appeared to increase 1 day prior to the onset of hemoglobin differentiation. The enzymatic activities of ATP polymerization in the nucleus of these erythrocytes were also examined. The enzymatic activity was resolved into two fractions on O-(diethylaminoethyl) cellulose. The ratio of the two enzymatic activities remained relatively constant in erythrocytes from 4- to 19-day-old embryos. However, a threefold increase in the total poly(A) polymerase activities was observed 1 day prior to the onset of hemoglobin differentiation. These results indicate that hemoglobin differentiation in these erythrocytes is associated with an increase in the rate of synthesis of poly(A)-containing RNA and in the activities of poly(A) polymerases.