Chromosomal proteins of rat brain: increased synthesis and affinity for DNA following a pulse of the carcinogen ethyinitrosourea in vivo.

A single pulse of ethlnitrosourea (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.