As has been well established, reticulocytes (RC) synthesize the species specific protein, globin, actively for about 24 hours or more till the time of their complete maturation1,2,3. This will be possible only in the presence of messenger RNA (m-RNA)4,5. Since the splendid hypothesis of m-RNA proposed by JACOB and MONOD6 for explaining the mechanism of the transfer of genetic information from nucleus to cytoplasm, it has largely been accepted through the numerous observations that followed7,8,9,10. However, the m-RNA hypothesis,
which has been deduced by observing the protein synthesis in E. Coli, includes the meaning of labile RNA which is incessantly decomposed and newly synthesized to compensate the rapid degradation. As m-RNA cannot be synthesized in
RC which have no detectable DNA, it has been supposed that the m-RNA of RC should be considerably stablell,12,13. Even in the denucleated cells, however, the RNA synthesis might be possible because Borsook reported the positive RNA
synthesis of RC14, and this result has recently been reconfirmed by BURNY15.</p