Redifferentiation, cellular elongation and the cell surface during lens regeneration

Abstract

ABSTRACT Dorsal irises from normal and lentectomized eyes of the newt Notophthalmus viridescens were cultured in vitro in the presence of colchicine (1·25 × 10−3 to 2·5 × 10−6 M), vinblastine sulfate (4·4 × 10−8) and cytochalasin B (20 μg/ml). Explants were treated for 24 h and implanted into host eyes of previously lentectomized newts. In regenerates treated with colchicine at stages prior to the onset of lens fiber formation, cellular elongation was inhibited or considerably delayed. Cytochalasin B has no effect on lens fiber differentiation when compared with regenerates treated with its solvent, dimethyl sulfoxide. Colchicine-treated regenerates showed no detectable fluorescence when stained with anti-newt lens fluorescent antibodies, suggesting that cells in which cellular elongation was inhibited were unable to synthesize lens specific proteins. Ultrastructural observations of elongating lens regenerate cells showed microtubules present in the cytoplasm parallel to the axis of elongation. Microtubules were not observed in depigmented cells from colchicine-treated regenerates. Characteristic vinblastine-induced microtubule crystals were present in depigmented cells from vinblastine-treated regenerates. Experiments using cell electrophoresis showed that neuraminidase-sensitive groups were detectable at the ionic double layer of cells from implanted regenerates at stages where lens fiber differentiation occurs. Cells from colchicine-treated regenerates showed no significant reduction of their electrophoretic mobility after neuraminidase treatment. This suggests that the appearance of some cell surface components in the redifferentiated cell may also be colchicine sensitive and probably mediated by microtubules.