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      DNA Repair in the Lens

      , ,
      Ophthalmic Research
      S. Karger AG
      Lens, Hydroxyurea, UV-DNA repair

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          During early embryonic life the lens becomes an autonomous organ system containing the proliferating cells which are the sole contributors to its growth; the lens becomes topographically divided into proliferative (epithelium) and nonproliferative (fiber) compartments (see, for review Cleaver [1]). In nondividing lens fibers, cell nuclei progressively lose DNA, degenerate and disappear [9]. Modak [8] and Modak and Unger-Ullman [10] that terminally differentiating and aging postmitotic cells accumulate lesions in their DNA due to defective DNA repair enzyme machinery. We have shown earlier [2] that as lens fiber cells differentiate there occurs a decrease in the rejoining capacity for single strand breaks in DNA. A precise analysis of DNA repair capacity in the entire lens, or in the epithelium, is hampered by the fact that during two-thirds of the developmental period the cell population increases rapidly [11]. Thus, to demonstrate DNA repair activity, it is necessary to suppress the normal cell division. To this end, we undertook the analysis of thymidine incorporation in the presence of hydroxyurea, a drug known [1] to inhibit scheduled DNA synthesis but not repair synthesis. Our data show that the drug does suppress the incorporation of <sup>3</sup>H-thymidine initially, it also causes stimulation of incorporation during the later phase. Similar to the rabbit lens epithelium [4], the central epithelium from adult bovine lenses has a very low mitotic index [ Tréton et al., unpubl.] indicative of a near total lack of cell proliferative activity. In these, we observe ultraviolet-induced <sup>3</sup>H-thymidine incorporation without the use of hydroxyurea. We also find that protofibers carry out unscheduled DNA synthesis similar to those in rat lens [6].

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          Author and article information

          Ophthalmic Res
          Ophthalmic Research
          S. Karger AG
          03 December 2009
          : 11
          : 5-6
          : 335-340
          Unité de recherches gérontologiques, U-118, Inserm, Paris and Unite de biologie du Développement, Institut de pharmacologie, CHUV, Lausanne
          265030 Ophthalmic Res 1979;11:335–340
          © 1979 S. Karger AG, Basel

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          Page count
          Pages: 6
          Growth Control, Differentiation, and Ageing of the Eye Lens

          Vision sciences,Ophthalmology & Optometry,Pathology
          UV-DNA repair,Lens,Hydroxyurea
          Vision sciences, Ophthalmology & Optometry, Pathology
          UV-DNA repair, Lens, Hydroxyurea


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