MICROSPECTROPHOTOMETRIC MEASUREMENTS OF THE DEOXYRIBONUCLEIC ACID (DNA) CONTENT IN TWO CHROMOSOMAL LINES OF THE EHRLICH ASCITES CARCINOMA

The DNA-content of hyperdiploid and hypotetraploid tumor cells of the Ehrlich ascites carcinoma was measured by Feulgen-microspectrophotometry, adopting the two-wave-length method (482mμ and 561mμ) in comparison with that of normal mouse monocytes and splenic cells. It was found that the DNA-content of nuclei was proportional to the number of chromosomes. The change of the DNA-content during mitosis was measured: it was shown that the mean amounts of DNA of small amount-nuclei at interphase were identical with those of anaphase and telophase nuclei, being just half the metaphasic amount. The amounts of DNA of prophase nuclei correspond to approximately three-quarters of those of metaphase nuclei. Based on the results of measurements of the DNA-content in relation to size of nuclei, the mechanism of DNA synthesis was discussed in connection with cell growth during interphase and prophase. A similar pattern of the correlation between nuclear size and the DNA-content was found to occur in hyperdiploid and hypotetraploid lines.