The administration of a single dose of aflatoxin B(1) to the rat (7mg./kg. body wt.) results in the slow development of a periportal necrosis. Hepatic enzymes are released into the serum in the second 24hr. of the poisoning, closely preceding the onset of the necrosis, which is followed by a rise in serum alkaline-phosphatase activity and bilirubin concentration. Aflatoxin B(1) has been detected in the nucleus of the poisoned liver cell and in vitro it has been shown to interact with DNA. The toxin inhibits the production of nuclear RNA, probably by preventing the transcription of DNA by the RNA polymerase. It is proposed that the interaction of the toxin with DNA gives rise to its inhibitory action on mitosis and its necrogenic action.

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From measurements of thermal hyperchromicity and the behaviour of an aflatoxin-DNA mixture on a Sephadex column it was concluded that aflatoxin B(1) is capable of weak binding to single-stranded DNA. The interactions of the aflatoxins (B(1), G(1) and G(2)) with nucleosides result in difference spectra and suggest that the purine bases and the amino group play a role in the binding of all the aflatoxins to DNA.

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