Attempts to induce cytogenetic effects with sulphite in sulphite oxidase-deficient Chinese hamsters and mice

Chinese hamsters and mice were made sulphite-oxidase deficient by the feeding of a low-molybdenum diet with sodium tungstate as a drinking-water supplement. Hepatic sulphite-oxidase activity was checked spectrophotometrically. Under normal conditions, sulphite-oxidase activity is high in the mouse and low in the Chinese hamster. Sulphite (SO 3 - -) was given in a single or double oral dose in aqueous solution or dissolved in fruit juice or by repeated subcutaneous injections up to the maximum tolerated doses. Possible cytogenetic effects were studied in bone-marrow cells using three test systems—the sister chromatid exchange, chromosome aberration and micronucleus tests. No induction of cytogenetic effects was observed with any of the three tests in either species, indicating that no damage at the chromosomal level was induced by sulphite in these animals, even when sulphite-oxidase activity was reduced to a very low level.