Autoradiographic study of DNA synthesis in homologous chromosomes distinguishable by morphology.

Abstract

Autoradiographic terminal labeling studies performed on leukocyte cultures of a man (A. de J.) and his son (H. de J.), both carriers of an enlarged satellite on a D-group chromosome, demonstrated that the morphological marker was a No. 15. Counts of grains on the long arms of the two chromosomes 15 showed that the marker chromosome was less heavily labeled than its normal homolog. This difference was highly significant in both cases. The marker chromosome was also shorter than its homolog, though not significantly so in one case. Possible interpretations of these findings, i.e., chromosomal polymorphism or autosomal lyonization, were discussed.