Large double minutes with ring‐shape and rod‐shape

摘要

High incidence of large double minutes (DM) was characteristic of one subline of the SEWA mouse ascites tumor. This subline, SEWA1R, was the one in which the new C-bandless chromosomes (CM) appeared. The incidence of large DM was associated with low incidence of DM per cell, low incidence of DM-carrying cells, and high incidence of CM-carrying cells. The large DM were either round or elongated (rod-shaped). Many of the former kind were suggestive of ring-shape and a few of the largest obviously constituted pairs of rings, free or interlocked. One configuration of 4 interlocked rings was evidently in its second mitotic generation; in the same cell another configuration of 2 pairs of interlocked rings had developed from 1 pair of free rings in the preceding generation. Possible relations between CM and large DM are considered.