PROTEIN-SYNTHESIS IN TISSUES CULTURED FROM THE BOVINE HOOF

The mechanical strength of the bovine hoof depends on keratinization o f cells in the germinal layers of the epidermis. Histological examinat ion of hoof tissues in calves and young heifers has identified disturb ances in this keratinization process which would result in ineffective hoof development and could precipitate lameness. Short-term culture o f bovine hoof tissue was used to investigate epidermal keratinization. Cell function remains viable in these cultures. The rate of protein s ynthesis, measured by [S-35]-methionine incorporation, continued for a t least 3 h in culture. Radiolabelled proteins in tissue homogenates w ere separated by SDS-polyacrylamide gel electrophoresis and characteri sed by fluorography and were representative of the proteins found in h oof tissue. Three prominent radiolabelled bands were identified as ker atins and actin by Western blotting. Immunohistochemistry showed that keratin was localised principally in the epidermal layers, and microau toradiography indicated that this was the major site of protein synthe sis. Hoof tissues cultured under these conditions provide a useful sys tem for studying the acute regulation of epidermal keratinization.