DNA SYNTHESIS IN BONE MARROW 

 STUDIED BY AUTORADIOGRAPHY 



L. G. Lajtha, R. Oliver and F. Ellis 

 Department of Radiotherapy, Oxford 



The purpose of this paper is to report on experiments on the incorporation 

 of ^-P orthophosphate, adenine ^^C, and formate ^*C into deoxyribo- 

 nucleic acid (DNA) by human bone marrow cells in vitro, and on the effect 

 of X-irradiation and aminopterin on the synthesis of deoxyribonucleic 

 acid. 



METHODS 



Cell suspensions from human bone marrows were cultured in a medium 

 containing 80 per cent fresh human serum and 20 per cent balanced salt 

 solution. The method of culture has been described in detail elsewhere 

 (Lajtha^). The labelled compounds were added to the culture medium : 

 5[j.c/ml medium ^-P orthophosphate (with less than 0-1 [i,g inactive PO4 



Figure 1. Localization of formate i*C in human bone marrow cells in vitro. 

 Stained autoradiographs. X 2000. 



buffer) : 0-5[j.c/ml medium adenine i-^C (specific activity 10[xc/mg) : 

 1 [j.c/ml medium formate ^^C (specific activity 15[xc/mg). The cultures 

 were incubated at 37° C for 2-48 hours, then smears were made, fixed in 

 95 per cent methylalcohol and hydrolysed in N HCl at 60° C for 6 minutes. 



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