Résumé
Striated musclecytoskeleton was studied by ultrastructure and electrophoresis.Treatment of sea bass white muscle myofibrils and glycerinatedfibres with calpain caused disruption of costameres, intermediatefilaments, and Z-line, without altering sarcomeres. V8 proteasealso caused loss of costameres and Z-line, and disruptedsarcomeres without affecting the intermediate filaments.Recombinant lipase caused loss of Z-lines and also sarcolemmadetachment, without changing sarcomeres or intermediatefilaments. DNase-1 removed thin filaments and partially removedZ-lines while leaving intact the sarcolemma attachments andintermediate filaments. Calpain, V8 protease, lipase and DNase-1treatments induced extensive loss of α-actinin from the Z-line, which could be related to titin cleavage (calpain, V8),phosphoinositide hydrolysis (lipase), and actin depolymerisation(DNase-1). These results show that the cytoskeletal componentsare independent of intact thin filaments.