Separation of ascites tumor cells rich in deoxyribonucleic acid by means of counter-streaming centrifugation.

The possibility of separating ascites tumor cells with different numbers of chromo somes by means of counter-streaming centrifugation has been studied with the hy perdiploid Ehnlich ascites tumor (ELD) and its hypertetraploid offshoot (ELT). From ELD a fraction significantly higher in deoxyribonucleic acid phosphorus (DNAP) per cell than the unfractionated suspension was obtained. Inoculated into a new mouse this fraction developed into a suspension which was invariably lower in DNAP per cell than the inoculum. Repeated inoculation of this fraction followed by further fractionation increased the mean number of chromosomes per cell, giving about twice the original number. When another fraction of ELD, which is low in DNAP, was inoculated, the tumor suspensionproducedshowed thesame valueofDNAF asthatoftheinoculum. Fractionation oforiginal ELT gave two fractions highinDNAP percell, one com posed chiefly of octoploid cells, and another of tetraploid and octoploid cells. The distribution of the different types of tumor cells upon the three fractions ob tained with counter-streaming ce.ntrifugation is not in keeping with that which should be expectedfrom theirvolumesand contentsofDNA.