Induction of Tumours in Mice with Tritiated Thymidine

Abstract

WE wish to record preliminary results of an experiment, in which we are investigating the possibility of inducing tumours in mice with tritiated thymidine. The β-particles from tritium incorporated into deoxyribonucleic acid (DNA) from ³H-thymidine produce an irradiation which primarily affects the cell nucleus, since about 90 per cent of the energy of these particles is dissipated within the nucleus. This procedure, therefore, enables one to distinguish in long-range experiments the results of nuclear damage from that caused by irradiation of whole cells and tissues, and to study the importance of nuclear damage in radiation carcinogenesis. It is desirable to do this, since there are many indications that alterations in deoxyribonucleic acid are involved in carcinogenesis in general. It is also commonly assumed that the tumour-inducing properties of ionizing radiations are mediated through changes in the nucleus, but there is no proof of this assumption.