Depigmentation of Hair in C57BL Mice after Injection of Irradiated Thymic RNA

Abstract

Ribonucleic acid extracted from the thymus of C57BL mice by the sodium dodecyl sulfate-phenol method was irradiated with 10⁶R of Co-60 γ-rays. After the exposure, Sephadex column chromatography revealed that 27.7 per cent of original RNA had been decomposed to smaller molecules with molecular weights below 10, 000. The irradiated solution was then injected subcutaneously to new-born mice of the same strain. White hairs were recognized in the fur of the mice in-jected with irradiated RNA solution, but not in the animals which received non-irradiated RNA. The difference in the proportion of depigmented hairs between the two groups was statistically significant. In later hair generations, white hairs were replaced by darker ones. A variation in the pigment content of cortical cells of dark hairs was also observed.