Arthur M. Hartman

The Effect of riboflavin on the bacterial synthesis of vitamin B12-active material in the rat

Abstract On B 12 -deficient rations that contained levels of the other B vitamins which were much higher than those required for optimal growth, a large proportion of negative control rats grew at a rate nearly equal to that of their B 12 -fed littermates, while the others grew much more slowly. The average growth rate and the proportion of such fast-growing negative controls increased, in general, with increased concentrations of B vitamins in the ration. The feeding, to slow-growing negative controls on a high B vitamin diet, of a single small dose of feces from fast-growing negative controls on the same diet, brought about a markedly increased growth rate; inclusion of sulfasuxidine in the ration delayed this effect for several weeks in practically all cases. Feeding these feces to animals on moderate levels of the B vitamins failed to bring about increased growth. These results indicated bacterial synthesis of B 12 -active material in the intestinal tract. Such synthesis was shown to be due to the high levels of dietary riboflavin. This finding is briefly discussed with regard to recent investigations on the chemical structure of vitamin B 12 and on related biochemical studies.

Influence of Vitamin B12 Upon Vaginal Patency in the Rat

Summary The onset of sexual maturity in female rats, as measured by vaginal patency, was found to be delayed in vit. B12-dencient animals as compared to vit. B ^-supplemented littermates when their mothers were fed a B12-dencient ration during lactation. No such differences were observed when the mothers were fed B12 during lactation. The nature of the carbohydrate and protein in the ration was found to have an effect on the differences observed.