RADIOACTIVE INDICATORS IN BIOCHEMISTRY 



987 



follow such a procedure since the ^^N content of the precursor of the 

 haemin nitrogen at different times of the experiment is not known. 



Shemin et aZ. (49) applied their i^N technique also to the study of the 

 life-span of the nucleated red blood corpuscles of the chicken. The life- 

 cycle of such corpuscles was found to be about 28 days, in good agree- 

 ment with the results obtained when using deoxyribonucleic acid ^^p 

 as an indicator. 



Radio-phosphorus was also applied in life-span determinations in a 

 different way, as described above. (•^°) By injecting, twice daily, labelled 



6-1 



o 



o 



2 4 



I 3- 



^ 2- 

 o 



. Plasma inorqanic P 



\ 





Granijlocyfe deoxyribonucleic 

 -» y acid P 



f\ 



Lymphocyte deoxyribonucleic 

 ' acid P 



Fig. 8. — Change of tlie specific activity of hutnan-plasma inorganic 

 phosphorus and white -corpuscle nucleic phosphorus with time. 



(Ottesen) 



Fig. 9 — Percentage of 

 human lymphocytes, formed 

 during the first day of the 

 experiment, present in the 

 blood stream at the time 

 indicated on the a;-axis 

 (Ottesen). 



Fig. 10. — Percentage of hu- 

 man granulocytes, formed du- 

 ring the first day of the ex- 

 periment, present in the blood 

 stream at the time indicated 

 on the ic-axis (Ottesen). 



^^^^Cold Spring Harbor Stjmp. Quant. Biol. 13, 185 (1948). 

 (so) Hevesy and Ottesen, Nature 156, 534 (1945). 



