Chromosome banding and DNA replication studies on a cell line of Dipodomys merriami

The chromsomes of a cell line of Dipodomys merriami are described in terms of their C-, G- and Q-banding patterns. Studies on the buoyant density of DNA made at different times in the S phase show that the replication of HSα satellite and AT-rich main band DNA occurs preferentially late in the S phase, whereas MS satellite and GC-rich main band DNAs are replicated early in the S phase. Autoradiographic studies of chromosomes labelled early or late in the S phase are used to relate the banding patterns nf particular chromosome regions to the fraction of DNA which they may contain.