Immunocytochemical identification of actin in mitochdria of Physarum polycephalum

Abstract Mitochondria isolated from the plasmodia of Physarum polycephalum Schw. are reacted with rabbit anti-actin anti-body, and detected with FITC-conjugated sheep anti-rabbit IgG antibody. The results of indirect immunofluorescence show that actin ex-ists in the mitochondria. Western blot analysis confirms the existence of actin in the protein preparation of the mitochondria. The indirectimmunoelectron microscopic observation using the same antibodies verifies further that actin is the constituents of mitochondria, and it isdispersively distributed in the mitochondria of P. polycephalum.