The Effect of X-irradiation on the Biosynthesis of Haemoglobin

Summary

1. A new method for the synthesis of δ-aminolevulinic acid-2, 3-¹⁴C has been described.

2. The incorporation of δ-aminolevulinic acid-2, 3-¹⁴C into haemin was measured in bone-marrow homogenates from irradiated rabbits.

3. At times between 0 and 28 days after 800 r of x-radiation, the cellularity of the marrow, measured as its DNA-content, was found to have decreased.

4. During the same period, the capacity of the homogenate to synthesize haemin from DAL also decreased. The changes observed could not be ascribed entirely to alterations in the cellularity of the marrow, and it is suggested that the synthesis of haemin per se is affected by radiation.

5. A comparison with a similar study with glycine-2-¹⁴C as a precursor of haemin has revealed that the reactions by which DAL is formed from glycine and acetate are markedly inhibited on the seventh day after irradiation.