NEAR-UV RADIATION DISRUPTS FILAMENTOUS ACTIN IN LENS EPITHELIAL-CELLS

Ultraviolet radiation in the near range (UV(A)) Causes lens opacificat ion and disrupts the actin cytoskeleton in rabbit and gray squirrel le nses. Changes were noted using transmission electron microscopy of tan gential sections and rhodamine-phalloidin fluorescence microscopy of e pithelial whole mounts of irradiated and unirradiated lenses, and corr esponded with gross cataract formation. Irradiated lenses lacked micro filament polygonal arrays at the inner surface of the apical plasma me mbrane (i.e., in the cell pole next to the lens fibers) in lens epithe lia of both species; a condensed actin bundle was present instead. Thi s bundle, and scattered small actin clumps in the cytoplasm, were iden tified by immunogold TEM, using a specific antibody and a secondary an tibody conjugated with colloidal gold. Similar techniques showed break down of tubulin and vimentin, but after longer intervals than for the breakdown of actin. Generalized cytologic damage was also present in e pithelial cells, but not in the underlying cortical lens fibers. Damag e began to occur after 4 hr of irradiation and became more severe with increased exposure. Shielded controls remained clear, had normal cyto logy and polygonal arrays, and no clumping of actin filaments. (C) 199 3 Wiley-Liss, Inc.