Elimination of the Effect of the Ay Gene on Pulmonary Tumors in Mice by Alteration of Its Effect on Normal Growth

Abstract

Yellow (A × Y)F₁ mice had more methylcholanthrene-induced pulmonary tumors and greater body weight and body size than did their brown litter mates. This confirmed earlier observations of the effect of the lethal yellow gene A^y on increasing pulmonary tumors and normal growth. When the difference in normal growth due to this gene was reduced by injection of goldthioglucose, which raised the weight of the browns almost to that of the yellows (whose weight was only slightly increased), the difference in tumor response due to the gene was eliminated. The average number of tumors in the treated browns was raised to a level comparable to that in the treated yellows. Inhibiting the effect of A^y on normal growth by restricting the food intake of the yellows—holding their weight to the level of the browns—reduced the average number of tumors in the yellows to that in the browns. These results suggest that the action of A^y in increasing the occurrence of pulmonary tumors is related to its action in increasing normal growth.