Presence of invertebrate dystrophin-like products in obliquely striated muscle of the leech, Pontobdella muricata (Annelida, Hirudinea)

Dystrophin is a 427-kDa cytoskeletal protein, which occurs in scant amounts in vertebrate muscle and nerve cells. No previous references to dystrophin or associated proteins in invertebrates at the protein level have been fou nd, while two recent studies investigated the presence of genes encoding pr oteins homologous to dystrophin in sea urchin and other invertebrates such as Drosophila melanogaster. In this study, the possible presence and distri bution of dystrophin-like proteins were studied in different invertebrate m uscle cell types and species through Western blot analysis and light and el ectron microscope immunohistochemistry using a panel of antibodies whose sp ecificities have been determined in vertebrates. Crude protein extracts of leech Pontobdella muricata were analysed by Western blotting. The revealed protein band, with 140 kDa molecular weight, was related to dystrophin, utr ophin or dystrophin-related protein-2 (DRP2) according to the specificities of the antibodies used to detect them. The immunofluorescence study showed positive immunoreactions in obliquely striated muscle of this hyrudinean. The immunoelectron microscopy study confirmed specific immunogold labelling beneath the sarcolemma of muscle cells. We thus assume that this protein i s an invertebrate dystrophin-like product that is referred to as IDLp140. T he potential functions of this invertebrate dystrophin-like protein in inve rtebrate muscles are discussed relative to previous data in vertebrate tiss ues.