Characterization and fine-structural localization of actin-and fibronectin-like proteins in planaria (Dugesia lugubris s.l.)

Abstract

Actin- and fibronectin-like proteins were characterized in the planarian, Dugesia lugubris s.l., by sodium dodecyl sulphate polyacrylamide gel electrophoresis and immunoblotting analysis using antisera to vertebrate actin and fibronectin. These antisera recognized protein bands of 42 kDa and 220 kDa, respectively. In addition, the immunohistochemical distribution of both actin- and fibronectin-like material was examined by using immuno-electron microscopy. Actin-like protein was localized in myofibrils in various differentiation stages, and in the peripheral cytoplasm and lamellipodia of cells that were migrating. The fibronectin-like component was associated with the extracellular matrix in the fibrillar structures and with the surface of the migrating cells. Our data suggest that similar cellular and molecular mechanisms are involved in cell-matrix interactions and in the morphogenesis of living organisms at different evolutionary levels.

Possible roles of extracellular matrix and cytoskeleton in leech body wall muscles

“…The results of immunofluorescence and Western blot analysis confirmed the detection of different proteins (present in the ECM and in the cytoplasm of the muscle fibres) in accord with those observed not only in leeches (Masuda‐Nakagawa et al ., 1988; Masuda‐Nakagawa & Nicholls, 1991) or in closely related phyla (Hung et al ., 1980; Pascolini et al ., 1992; Suzuki & Funakoshi, 1992; Di Rosa et al ., 1994), but also in smooth and cross‐striated muscles of vertebrates (North et al ., 1993; Small et al ., 1992). It may be that the presence in many invertebrates of ECM components, with a distribution and biochemical and immunological properties similar to those of vertebrates, could be another example of evolutionary conservation like the presence of actin and myosin systems beginning from protozoa or muscle developmental control mechanisms.…”

Cell-, tissue-, and position-specific monoclonal antibodies against the planarian Dugesia (Girardia) tigrina

“…However, despite these advantages, the number of molecular markers for specific tissues, cell types or positions is rather limited: neurotransmitters (serotonin, acetylcholinesterase, dopamine) and neuropeptides (FMRFamide, neuropeptide F, small cardiac peptide, substance P, and Met and Leu-enkephalin among others) for nerve cells (summarized in Gustafsson et al 1986;Reuter et al 1988;Fairweather and Skuce 1995;Reuter and Gustafsson 1995) melanin and tyrosinase for pigment cells (Palladini et al 1979a, b); actin for muscle cells (Pascolini et al 1992); acid and alkaline phosphatase and some neuropeptides for intestinal cells (Reuter and Palmberg 1987); eosinophilic and cyanophilic granules for secretory cells (Pedersen 1959a(Pedersen , 1961; rhabdite granules for epithelial cells (Hori 1978); and fibronectin, laminin and collagen IV for basal membrane and the extracellular matrix (Lindroos and Wikgren 1987). Moreover, these cytological and histochemical markers have, in general, not been used for studies of cell replacement, cell differentiation or pattern formation.…”

Cytoskeletal protein expression in planarians

“…In the free-living flatworm planarian, actin has been localized mainly in muscle cells and in migrating phagocytic cells and Me-Cs (Pascolini et al, 1988(Pascolini et al, , 1992b. The existence of at least two major actin isoforms has been demonstrated by isolectric focusing, oneand two-dimensional SDS-PAGE and Western blotting analyses (Panara et al, 1992;Pascolini et al, 1992a).…”

“…Like vertebrates, (Woodcock-Mitchell et al, 1988) planarian mioblasts expressed a-sm actin-like protein during the first stages of development, but the cytoplasm, not the differentiating myoflbre, was labelled (Pascolini et al, 1992a). In planarians, a FN-like protein is expressed at the level of plasma membrane of Me-Cs apparently moving into the blastema area (Pascolini et al, 1992b). The localization of this adhesion molecule around cells which express a-sm actin-like antigen (Pascolini et al, 1992a) confirms that, likewise vertebrates, the FN-and a-sm actin-like protein expression may be correlated.…”

“…lc) and growth (Pascolini et al, 1992a(Pascolini et al, , 1993. The expression of a-sm actin-like molecule, assayed by Western-blotting analysis, markedly increased during regeneration and growth (Pascolini et al, 1992b(Pascolini et al, , 1993. These biochemical data are closely related to the increased number of activated Me-Cs, which are responsible for the blastema formation and growth.…”