516 J. BRACKET 



autoradiographic observations by Ficq-'*^ and by Ficq and Errera-"** have 

 shown, in the liver, a much higher incorporation of radioactive glycine into 

 the nuclear proteins than into the cytoplasmic ones; in the starfish oocyte 

 (Ficq2'*2), incorporation of the labeled amino acid into the nucleolar pro- 

 teins is unusually high and fast. The obvious discrepancy between the bio- 

 chemical and the autoradiographic results, in the case of the liver, might 

 well be due to the fact that the active nuclear proteins are apparently very 

 soluble: treatment of the sections with media generally used for the isola- 

 tion of nuclei in homogenates (citric acid, sucrose, etc.) markedly decreases 

 the radioactivity of the nuclei (Ficq and Errera-''*). Experiments on the 

 incorporation of labeled amino acids with the proteins of nuclei isolated in 

 non-aqueous media should throw additional light on the question. If the 

 autoradiographic observations are correct, the situation regarding the in- 

 corporation of labeled precursors into the nucleus and the cytoplasm is the 

 same for PNA and proteins: in both cases, incorporation is faster in the 

 nucleus than in the cytoplasm, but appreciable synthesis nevertheless occurs 

 for a considerable time in non-nucleated cytoplasm. That protein synthesis 

 can go on in the absence of the nucleus has again been confirmed with 

 reticulocytes by recent experiments of Nizet and Lambert-^^ and from 

 Koritz and Chantrenne.^^" It is interesting, in this respect, to mention that 

 autoradiographic observations by Gavosto and Rechenmann-" have con- 

 clusively shown that decrease in PNA content and decrease in glycine in- 

 corporation into the proteins run perfectly parallel during the maturation 

 of the reticulocytes. 



The lively and interesting discussion which has gone on regarding the 

 template theory of protein synthesis can only be mentioned here (Campbell 

 and Work,^^-"^ Dounce,2^^-55 Gale^^^ Dalgliesh^") ; new evidence has been 

 brought forward in favor of the view that protein synthesis occurs at the 

 expense of free amino acids (Halvorson and Spiegelman^^^-^^); but An- 

 finsen and Flavin-^" have extended to ribonuclease their earlier findings on 

 ovalbumin, indicating rather a stepwise synthesis of proteins. In connec- 



2« A. Ficq and M. Errera, Biochim. ct Biophys. Acta 16, 45 (1955). 



2" A. Nizet and S. Lambert, Bull. soc. chim. biol. 35, 771 (1953). 



"0 S. B. Koritz and H. Chantrenne, Biochim. el Biophys. Acta 13, 209 (1954). 



261 F. Gavosto and R. Rechenmann, Biochim. et Biophys. Acta 13, 583 (1954). 



262 P. N. Campbell and T. S. Work, Nature 171, 997 (1953). 

 2" p. N. Campbell and T. S. Work, Nature 172, 541 (1953). 

 2" A. L. Bounce, Enzyrnologia 15, 251 (1952). 



266 A. L. Bounce, Nature 172, 541 (1953). 



266 E. F. Gale, Advances in Protein Chem. 8, 285 (1953). 



267 S. C. Balgliesh, Nature 171, 1027 (1953). 



268 H. O. Halvorson and S. Spiegelman, /. Bacteriol. 65, 496 (1953). 



269 H. O. Halvorson and S. Spiegelman, /. Bacteriol. 65, 601 (1953). 

 260 C. B. Anfinsen and M. Flavin, Federation Proc. 12, 170 (1953). 



