Actin filament localization in normal and migrating rabbit corneal epithelium.

The molecular probe NBD phallacidin (7-nitro-benz-2-oxa-1, 3-diazolylphallacidin), which reacts specifically with filamentous actin (f-actin), was used to study the distribution of polymerized actin oligmers in normal and migrating rabbit corneal epithelial cells. In the normal cornea, the majority of the NBD phallacidin fluorescence was localized to the cortical or sub-plasma membrane area of the superficial and wing epithelial cells. Following full thickness corneal trephination injury, migrating corneal epithelial cell exhibited a marked increase in the cortical NBD phallacidin fluorescence. Transmission electron microscopy, using fixation techniques which revealed bundles of fine filaments (6nm underlying the plasma membrane of migrating epithelial cells, thus supporting the fluorescent results. These findings suggest that corneal re-epithelialization is characterized by a marked increase in the amount of filamentous actin within the migrating epithelial cells. We conclude that NBD phallacidin may be of value in analyzing changes in actin polymerization during wound healing.