• 1 January 1981
    • journal article
    • research article
    • Vol. 41  (5) , 1829-1833
Abstract
The numbers of UV-induced pyrimidine dimers in the DNA of neonatal BALB/c mouse skin were measured by assessing the sensitivity of the DNA to Micrococcus luteus UV endonuclease. Irradiation of neonatal BALB/c mice with FS40 sunlamps caused a dose-dependent induction of endonuclease-sensitive sites (pyrimidine dimers) in DNA extracted from back skin. Exposure of these UV-irradiated neonatal mice to photoreactivating (PR) light (cool white fluorescent lamp and incandescent lamp) caused a reduction in the number of pyrimidine dimers in the DNA, as revealed by a shift in low MW DNA to high MW DNA. DNA profiles of the skin of UV-irradiated mice of UV-irradiated mice kept in the dark for the same duration as those exposed to PR light did not show a loss of UV-induced endonuclease-sensitive sites. Reversing the order of treatment, i.e., administering PR light before UV, did not reduce pyrimidine dimers. PR of UV-induced pyrimidine dimers occurs in neonatal BALB/c mouse skin. The optimal wavelength range for in vivo PR appears to be in the visible region of the spectrum (> 400 nm). Although dimer formation could be detected in dermis and epidermis, PR occurred only in the dermis. The PR phenomenon could not be detected in the skin of adult mice from the same inbred strain. [Exposure of mice to UV light induces skin cancer.].