J. Biol. Chem., Vol. 262, Issue 31, 15071-15075, 11, 1987
A high melting (105 degrees C) form of chromatin characterizes the potential of cells for mitosis
M Almagor and RD Cole
Department of Biochemistry, University of California, Berkeley 94720.
The nuclei from different types of dividing cultured cells melted as four
thermal transitions: I (60 degrees C), II (76 degrees C), III (88 degrees
C), and IV (105 degrees C). The fourth transition was the predominant
endotherm in all types of cells examined. In the melting profile of nuclei
obtained from nondividing density-inhibited fibroblasts, transition IV
remained the major endotherm; however, it was lost in nuclei from
differentiated myoblasts and nutrient-depleted cells. In these cells, the
loss in transition IV was compensated by a concomitant increase in
transition III. In the nutrient-deprived cells the decrease in transition
IV was followed by a gradual lowering in its melting temperature. The
complete loss of transition IV was correlated with loss of cellular
capacity to divide.