THE NUCLEIC ACID CONTENT OF TISSUES AND CELLS 47 



articles in tumor cells is accompanied by higher PNA-P/N values in both 

 these particles and the supernatant fraction (see also ref. 159, Table IX). 



Klein, Rasch, and Swift-'"' find that during the production of tumors in 

 the stems of the broad bean with Agrobacterium ruhi, the DNA concentra- 

 tion increased to a peak with little change in PNA concentration and 

 intensive cell division occurred; with indoleacetic acid, on the other hand, 

 there was a 50 % increase in PNA concentration in the first 2 days, and a 

 decline in DNA concentration, accompanying the enlargement of cells. 

 Indoleacetic acid(IAA) was also used by Silberger and Skoog-*^ to induce 

 changes in cultures of pith tissue of Nicotiana tahacum stems. The higher 

 concentrations (1.4 mg./l.) of lAA caused cell enlargement and a greater 

 increase in PNA than DNA. With much lower concentrations, DNA was 

 preferentially increased, and cell division was in evidence. 



When the DNA content was measured in the cells of the DBA mouse 

 ascites thymoma. Levy et alr^^ found that the peak in the DNA content 

 per nucleus coincided with peak values for PNA per cell. Klein and Forss- 

 ]rjgj.g243 report reasonably good agreement between the Schmidt and Thann- 

 hauser and Schneider methods, when applied to the Ehrlich ascites tumor. 

 Following irradiation of mice with 1250 r., there was a nearly linear increase 

 in the PNA and protein per cell, without any corresponding synthesis of 

 DNA; the cell volume increases and the DNA concentration decreases 

 during the period in which mitotic figures disappear. 



Papers by Mandel and his colleagues cover a variety of topics. Continu- 

 ing their studies on the action of X-rays on spleen and bone marrow, they 

 find that a single dose of 700 r. causes a greater reduction in the PNA and 

 DNA content per spleen than the same dosage given in two fractions at a 

 7-day interval.^^* In groups of rats injected with 0.5% alloxan solution, 

 there are 16.7 and 18.1 % reductions in the DNA and PNA content of the 

 pancreas, respectively, 2 days after administration, and smaller and less- 

 prolonged reductions in liver PNA and DNA."^^ On the other hand, Bass 

 et al}^^ report that the increase in DNA content per liver which occurred 

 in their alloxan diabetic rats was a direct effect of the alloxan on the liver 

 cells, and was not a consequence of the diabetic state. In a more detailed 

 account of earlier work (ref. 173, Table X) on the influence of insulin on 



s-'o R. M. Klein, E. M. Rasch, and H. Swift, Cancer Research 13, 499 (1953). 



2" J. Silberger, Jr., and F. Skoog, Science 118, 443 (1954). 



2" H. B. Levy, H. M. Davidson, R. W. Reinhart, and A. L. Schade, Cancer Research 



13,716 (1953). 

 2« G. Klein and A. Forssberg, Exptl. Cell Research 6, 211 (1954). 

 2^^ C. M. Gros, P. Mandel, and J. Rodesch, Compt. rend. soc. biol. 147, 1279 (1953). 

 2*^ J. D. Weill, P. Mandel, and O. Zalis, Compt. rend. soc. biol. 147, 1288 (1953). 

 2« A. D. Bass, H. F. Diermeier, H. S. Di Stefano, and E. J. Cafruny, /. Pharmacol. 



Exptl. Therap. 107, 478 (1953). 



