MOLYBDENUM 271 



Typical Methods. The 10 g M0O3 in the irradiation unit was dissolved 

 in 35 ml of 14.3 per cent NaOII and stirred until clear, after which it was 

 diluted to a convenient volume with distilled water to give a pll near 7 

 (]\Io-3). For tissue distribution studies about 7 g of the M0O3 was 

 administered orally to cattle, 1.9 g given intravenously to cattle, and 

 about 40 mg given orally to rats. The tissues were wet-ashed in concen- 

 trated HNO? and extracted with isoamyl alcohol to give two solutions for 

 each sample which were counted directly with a Geiger tube. In a stud}' 

 with plants, carrier-free Mo^^ and Mo^* produced in the cyclotron were 

 used (Mo-5). It was thus possible to study the uptake of as little as 1 yug 

 molybdenum by tomato plants from nutrient solutions. To demonstrate 

 that molybdenum is part of xanthine oxidase, about 15 mc Mo''^ was 

 injected into a dairy cow, and the Mo^^/xanthine oxidase ratio was fol- 

 lowed through several purification steps (Mo-1). The radioactivity was 

 measured by gamma counting. 



Mo-1. Totter, John R., William T. Burnett, Jr., R. A. Monroe, Ira B. Whitney, and 



C. L. Comar: Evidence that Molybdenum Is a Non-dialyzable Component of 



Xanthine Oxidase, Science, 118: 555 (1953). 

 Mo-2. Monier- Williams, G. W.: "Trace Elements in Food," John Wiley & Sons, Inc., 



New York, 1950. 

 Mo-3. Comar, C. L., Leon Singer, and George K. Davis: Molybdenum Metabolism 



and Interrelationships with Copper and Phosphorus, J. Biol. Chem., 180: 



913-922 (1949). 

 Mo-4. Dick, A. T., and J. B. Bingley: Further Observations on the Determination 



of Molybdenum in Plant and Animal Tissue, Australian J. Exptl. Biol. Med. 



Sci., 29: 459-462 (1951). 

 Mo-5. Stout, P. R., and W. R. Meagher: Studies of the Molybdenum Nutrition of 



Plants with Radioactive Molybdenum, Science, 108: 471-473 (1948). 



