Abstract
The synthesis of DNA in growing yeast cells was investigated after photodynamic treatment of the cells with thiopyronine (TP) and visible light or with 8-methoxypsoralen (8-MOP) and UVA light. DNA synthesis was inhibited after photodynamic treatment with 8-MOP but not after photodynamic treatment with TP. This result is further evidence that the photodynamic effect with TP does not attack nuclear DNA in eucaryotic cells.