MONITORING ULTRAVIOLET‐B‐INDUCED DNA DAMAGE IN INDIVIDUAL DIATOM CELLS BY IMMUNOFLUORESCENT THYMINE DIMER DETECTION¹

Abstract

We developed a method to investigate the effect of ultraviolet‐B radiation (UVBR) on the formation of thy‐mine dimers in microalgal DNA that can be used for both laboratory and in situ research. Antibody labeling of dimers was followed by a secondary antibody (fluorescein isothiocyanate) staining to allow visualization of DNA damage with flow cytometry or fluorescence microscopy. Thymine dimer‐specific fluorescence in nuclear DNA of the marine diatom Cyclotella sp. was linearly related to the UVBR dose. Simultaneous measurements of cellular DNA content showed that the vulnerability of G2 cells to DNA damage did not differ significantly from the vulnerability of G1 cells. The formation and removal of thymine dimers in Cyclotella sp. cells was monitored for 3 consecutive days at two realistic UVBR irradiance levels. Thy‐mine dimers were removed within 24 h when exposed to a saturating photosynthetically active radiation intensity following the UVBR treatment. This new method allows the study of UVBR‐induced DNA damage on a cell‐to‐cell basis. It is also feasible for field studies because cells remain intact and can be recognized readily after antibody treatment.

Effects on aquatic ecosystems

“…One of the major targets is the DNA, which strongly absorbs in the short-wavelength range of solar radiation. Solar UV-B has been found to induce DNA damage and DNA synthesis delay in many organisms [98][99][100][101]. UV-B effects have also been studied on the ecosystem level using mesocosms [102,103].…”

ULTRAVIOLET SUNSCREENS IN GYMNODINIUM SANGUINEUM (DINOPHYCEAE): MYCOSPORINE‐LIKE AMINO ACIDS PROTECT AGAINST INHIBITION OF PHOTOSYNTHESIS

“…Solar ultraviolet (UV, 290-400 nm) radiation affects phytoplankton growth and survival in near-surface waters by the inhibition of photosynthesis (Smith et al 1980, Helbling et al 1992, Smith et al 1992, damage to DNA (Karentz et al 1991a, Buma et al 1995, and effects on other processes (HolmHansen et al 1993). Concern about stratospheric ozone depletion and the associated enhancement of middle ultraviolet (UVB, 290-320 nm) has motivated spectral assessments of UV inhibition of photosynthesis to distinguish effects by UVB compared to the near ultraviolet (UVA, 320-400 nm), which is unaffected by ozone depletion (Cullen et al 1992, Lubin et al 1992, Boucher and Prezelin 1996a, Neale et al 1998a.…”

Detection of UVBR-sensitive and -tolerant bacteria in surface waters of the western North Pacific

“…An immunological technique for detecting DNA damage of marine microorganisms has been developed by Buma et al [21] and has been widely used to quantify thymine dimers [22].…”