Polyamines in Normal and in Virus-transformed Chick Embryo Fibroblasts

Cultures of normal and Rous sarcoma virus-transformed chick embryo fibroblasts were assayed for their ribonucleic acid, protein, and polyamine content. Transformed cultures did not differ from normal ones in their protein and ribonucleic acid content when grown under optimal conditions. Changing the growth medium resulted in a sharp increase in putrescine and spermidine levels in both normal and transformed cells. Transformation had no significant effect on cellular spermine levels, while a slight decrease in spermidine content was observed. On the other hand, putrescine levels were three to seven times higher in transformed cells than in normal controls, mainly in old primary cultures. The difference between normal and transformed cultures was most apparent in tertiary cultures when all the cells were transformed. There, the molar putrescine/spermidine ratio was 10 times higher in the transformed cells compared to the normal controls.