Chromosome Studies on Polyploid Cell Strains ofChinese HamsterIII: DNA Replication Sequence

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Abstract
A study has been made, by means of autoradiographic methods, of the final part of the period of DNA synthesis in aneuploid diploid cells of the Chinese hamster, cultivated in vitro, and in stabilized polyploid cells derived from them. The results have shown that, in the polyploid lines, chromosomes or parts of chromosomes have not become late-replicating if they were not so in the diploid cells. The reverse, however, remains an open possibility: namely, the reversion of the heterochromatin of an arm of the presumed X-chromosome. It has also been observed that, in the polyploid lines, the large and medium metacentric chromosomes end their synthesis earlier than in the diploid line.