COMPARATIVE RESPONSE TO UV IRRADIATION OF CYTOSKELETAL ELEMENTS IN RABBIT AND SKATE LENS EPITHELIAL-CELLS

Purpose. This work reports a differential effect of ultraviolet A (UVA ) irradiation on the three major cytoskeletal structures, actin and vi mentin filaments and microtubules of lens cells in primary culture. Th e effect on cells from lens of the skate (a bottom-dwelling marine ela smobranch) was compared with that on rabbit lens, in order to assess U VA sensitivity as a function of exposure to these wavelengths in the n ative habitat. Methods. Exposure intervals of irradiation time up to 6 hours were selected, at fluences from 13.5 to 54.4 J/cm(2) and at 365 +/- 45 nm wavelength, to represent mild to moderate physiological lev els. Cultures were fixed and processed with anti-alpha-tubulin-FITC an d rhodamine phalloidin, or with anti-vimentin FITC and rhodamine phall oidin conjugates. Results. With epifluorescence microscopy, it was fou nd that microtubules were most sensitive to UVA irradiation (in depoly merizing), followed by actin, with vimentin hardly at all affected. Ir radiation for 6 hours followed by incubation for 3 days in fresh mediu m showed no recovery of actin but good recovery of microtubule organiz ing centers, followed by mitosis in many (rabbit) cells. Skate cells w ere more sensitive and showed no recovery. Conclusions. In view of the role of cytoskeletal elements in intracellular structure, cell divisi on and transport, their disruption supports the hypothesis that UVA ma y damage lens epithelial cells in vivo so as to contribute to cataract formation. In addition, the data suggest that the lenses of animals e xposed to sunlight require effective cytoskeletal repair mechanisms to avoid loss of function.