Chromosomal proteins of rat brain: Increased synthesis and affinity for DNA following a pulse of the carcinogen ethylnitrosourea in vivo

A single pulse of ethylnitrosourea (EtNU), administered to 10‐day‐old BD IX‐rats, specifically results in a high incidence of neuroectodermal tumors in the central and peripheral nervous system. At five days after an EtNU‐pulse, analyses of protein‐DNA interactions were performed using chromatin dissociation and re‐association experiments, following incorporation of radioactive leucine into brain chromosomal proteins (CP) during short‐term suspension culture. In comparison with 15‐day‐old control animals, the brain cells of EtNU‐treated rats exhibited (i) an increased rate of CP synthesis, and (ii) an increased affinity of the newly‐synthesized CP for brain DNA of both control and EtNU‐treated animals.