Analysis of histone in situ in developmentally inactivated chromatin.

13 Holland, J. J., these PROCEEDINGS, 50, 436 (1963). 14 Frederiksen, S., and H. Klenow, Biochem. Biophys. Res. Commun., 17, 165 (1964). 15 "Deoxyribonuclease I, free of ribonuc lease, obtained from Worthington Biochemicals, Freehold, N. J. 16 Britten, R. J., and R. B. Roberts, Science, 131, 32 (1960). 17 Bray, G. A., Anal. Biochem., 1, 279 (1960). 18 S values for components sedimenting in sucrose gradients were calculated by the method of Rt. Martin and B. Ames [J. Biol. Chem., 236, 1372 (1961)] assuming the value of 18S for the optical density peak of intermediate sedimentation velocity obtained from rat liver RNA (see ref. 10). 19 The phenomenon of decreasing RNA synthesis in nonstimulated lymphocyte cultures is not clearly understood. Independent evidence has shown that cell destruction or loss of viability are not major factors (see ref. 6). 20 Girard, MI., S. Penman, and J. E. I)arnell, these PROCEEDINGS, 51, 205 (1964). 21 Scherrer, K., H. Latham, and J. E. Darnell, these PROCEEDINGS, 49, 240 (1963). 22 Perry, R. P., these PROCEEDINGS, 48, 2179 (1962). 23 Fenwick, MI. L., Biochim. Biophys. Acta, 87, 388 (1964). 24 Pearmain, G., R. R. Lycette, and P. H. Fitzgerald, Lancet, I, 637 (1963). 25 Ling, N. R., and E. M. Husband, Lancet, I, 363 (1964).