Double minutes and other chromosomal aberrations in malignant cell line of Shionogi carcinoma 115.

G-banded karyotypes and structural abnormalities of chromosomes are described in two clones of the mouse mammary carcinoma SC 115 cell line. The cells showed multiple numerical and structural abnormalities. Structural anomalies, such as double minutes, acentric fragments, gaps or breaks, radials, ring chromosomes, endoreduplications, dicentrics, and elongated chromosomes were observed in varying proportions. Unstable chromosomal aberrations, such as breaks, gaps, fragments, and radials, frequently appeared without any particular pretreatment. Increased numbers of double minutes per cell correlated positively with the presence of elongated chromosomes, which did not contain homogeneously staining regions by the G-band technique.