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A Change in a Transplantable Anaplastic Carcinoma by Passage through X-radiated F Mice

( Biological Station of Roswell Park Memorial Institute; Springville, New York)

Mice of the F strain, normally resistant to pBr tumor, have been irradiated with 350 r, 400 r, or 500 r and found to permit growth of the pBr tumor for 5–30 days. The tumor has been carried through more than 35 transplant generations.

When nonirradiated F mice were challenged with the pBr tumor from irradiated mice, a 30.6 per cent transitory take resulted. When nonirradiated pBr mice were challenged with the same tumor, an 87.4 per cent take resulted. In genetic tests, a 30 per cent take was recorded in F₁ (pBr x F) and a 2.8 per cent take in backcross generation (F₁ [pBr x F] backcrossed to F).

The data presented indicate that the tumor requires four genes for progressive growth. This observation is significantly different from that reported by Strong (12) and by Strong and Hardy (14) showing that only three genes were necessary.

^* Submitted as part of the trainee program of the Biological Station of Roswell Park Memorial Institute in cooperation with Griffith Institute and Central School, Springville, N.Y. The author wishes to acknowledge the assistance and advice of Dr. Leonell C. Strong, Mr. L. B. Hardy, and Mr. H. L. Babbitt and extends to them his appreciative thanks.

Received 9/14/59.