994 SHORE ET AL, 12. R. Rugh, The Impact of Ionizing Radiations on the Embryo and Fetus, Amer. J. Roentgenol. Radium Ther. Nucl. Med., 89:182-190 (1963). 13. J. G. Wilson, Differentiation and the Reaction of Rat Embryos to Radiation, J, Cell, Phystol., 43, Suppl. No. 1: 11-37 (1954). 14. R. Rugh and E. Grupp, Exencephalia Following X-irradiation of the Preimplantation Mammalian Embryo, J. Neuropathol. Exp. Neurol., 18: 468-481 (1959). 15. C. H. Smith and M. L. Shore, Impaired Development of Rat Liver Enzyme Activities at Birth After Irradiation in Utero, Radiat. Res., 29: 499-504 (1966). 16. M. T. Wagner, dr., Influence of Gamma Irradiation {n Utero on the Development and Functional Adaptation of Selected Enzymes in the Beagle, Ph D. dissertation, Colorado State University, 1967. 17. J. de Vellis, O. A. Schjelde, and C. D. Clemente, Protein Synthesis and Enzyme Patterns in the Developing Brain Following Head X-Irradiation of Newborn Rats, ¢, Newrochem., 14: 499-511 (1967). 18. D. B. Duncan, Iultiple Range and Multiple F Tests, Biometrics, 11: 1-42 (1955). 19. J. W. Littlefield and E. B. Keller Incorporation of C'4’—Amino Acids into Ribonucleoprotein Particles from the Ehrlich Mouse Ascites Tumor, J, Biol. Chem,, 244: 13-30 (1957). 20. G. A. Bray, A Simple Efficient Liquid Scintillator for Counting Aqueous Solutions in a Liquid Scintillation Counter, Anal. Biochem., 1: 279 (1960). 21. A. S. Weisberger, S. Armentrout, and S. Wolfe, Protein Synthesis by Reticulocyte Ribosomes. I. Inhibition of Polyuridylic Acid Induced Ribcso- mal Protein Synthesis by Chloramphenicol, Proc. Nat, Acad. Sct. (U. S.), 50: 86-93 (1963). OPEN DISCUSSION GLASSER: Dr. Shore, do your irradiated mothers experience an anorexic period? SHORE:I really cannot tell you. We cid not make such a measurement, GLASSER: What is the incorporation of !{C phenylalanine into the dam? SHORE: We concentrated strictly on the fetus. We have done studies on the effects of radiation on liver enzyme synthesis in adult and adolescent rats. We found effects that parallel the slope we found here, MAHLUM: Have you looked at incorporation at earlier times after radiation to account for the difference in the weight that you see in the 24-hr period? SHORE: Yes, we have, and this is what has led us to these interesting lines of thought.