[Fluorometric analysis of the formation and repair of DNA breaks in irradiated cells].

A study was made of the dependence of the fluorescence of ethidium bromide upon NaOH concentration after staining of single- and double-strand DNA fragments. The possibility of the fluorometric estimation of the share of double-stranded DNA in cell lysates was demonstrated. The method of fluorometry was used to study the dose dependence of a change in the share of double-stranded DNA in the irradiated thymocytes and Ehrlich ascites carcinoma cells which permitted to determine the appearance and repair of DNA breaks in these cells.