Abstract
To determining possible minute amounts of DNA lesion caused by the natural sunlight, sensitive ELISA is the key. ELISA responses of cyclobutane pyrimidine dimer (CPD) and (6-4) photoproduct (6-4PP) have been discovered to be strikingly amplified when sodium chloride is applied together with DNA to ELISA plates. The salt effect occurred most effectively on Immulon 4HBX plates, slightly less effectively on 2HB and scarcely on 1HB. With Nunc plates, even a slight suppression was observed. Examination of various kinds of inorganic salts on 4HBX plates led us to conclude that both Na+ and Cl- are likely functional in amplification. Exceptionally potassium bromide and potassium iodide were promotive, while lithium chloride was ineffective. The rate of amplification was identical regardless of the extent of lesion at a fixed salt concentration, and hence this novel effect of salts serves for sensitizing ELISA of CPD and 6-4PP.
