This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Henson, P. Articles by Little, J. B. Search for Related Content PubMed PubMed Citation Articles by Henson, P. Articles by Little, J. B.

Excision of Ultraviolet Damage and the Effect of Irradiation on DNA Synthesis in a Strain of Bloom's Syndrome Fibroblasts¹

Laboratory of Radiobiology, Harvard University, School of Public Health, Boston, Massachusetts 02115

We have studied repair of ultraviolet light (UV)-induced damage in a strain of Bloom's syndrome cells which we have shown to be defective in host cell reactivation of UV-irradiated herpes simplex virus. Excision repair was monitored by following loss of sensitivity of DNA in permeabilized cells to digestion by the Micrococcus luteus UV endonuclease preparation. The Bloom's syndrome fibroblasts apparently removed endonuclease-sensitive sites from the DNA slightly less efficiently than did normal strains. After 24 hr, 38% of the sites remained in the Bloom's syndrome cells in comparison with 16% in normal fibroblasts.

DNA newly synthesized in UV-irradiated Bloom's syndrome cells sedimented less far into alkaline sucrose gradients than did DNA from similarly treated normal cells. In other respects, including the effect of caffeine exposure, DNA synthesis in Bloom's syndrome cells was indistinguishable from that in normal cells. We were therefore able to detect only minor defects in the repair of UV-induced damage in Bloom's syndrome fibroblasts. This is consistent with the normal survival exhibited by these cells. The defect in excision repair may, however, be sufficient to allow the cellular repair capacity to become saturated at high infecting multiplicities of UV-irradiated herpes simplex virus.

¹ This research was supported by Research Grants CA-11751 and ES-00002 and Training Grant AG-05015 from NIH.

² Present address: Stauffer Chemical Co., 400 Farmington Avenue, Farmington, Conn. 06032.

Received 12/ 4/78. Accepted 11/10/80.