[Study by fluorescence of DNA treated by 7-methyl-benzo (a) anthracene in the presence of a microsomal oxidation system].

When calf thymus DNA is treated with 7 methyl benzo(a)anthracene is presence of NADPH requiring microsomal hydroxylating system, the fluorescent signal observed on DNA after purification of the macromolecule shows the presence of 2 kinds of the hydrocarbon metabolites. One would countain probably a conjugated system analogous to the parent hydrocarbon ones, the other corresponds to a reduced conjugated system.

[Chemical cancerization of hamster embryo cells in mass culture].

For periods between 24 and 72 hours mass cultures of hamster embryo cells were put in contact with the following carcinogens: 7,10-dimethylbenz (c) acridine (2 mug/ml), benzo (a) pyrene (0,1 mug/ml), 7-methyl benz (a) anthracene (5 and 10 mug/ml), 3-methyl-cholanthrene (0,1 mum/ml), and 7,12-dimethyl benz (a) anthracene (0,05 mug/ml). The cancerisation of cells thus treated was demonstrated by hamster grafting as soon as 4 1/2 months post-treatment. By contrast neither the cells treated by benzo (e) pyrene (non-carcinogenic in animals) nor those of the two control lines resulted in tumours when grafted into hamsters even after culture for 8 and 15 months.

[Effect of a microsomal system on the toxicity and on the interactions of various polycyclic carconogenic hydrocarbons with cells in culture].

The addition of a liver microsomal system (extracted from phenobarbital pretreated hamster livers) to hamster embryo cell cultures, together with a carcinogenic hydrocarbon, reduces the hydrocarbon toxicity and increases the velocity of hydrocarbon uptake by cells.