Meeting Abstract
Extracellular matrix interactions with cells affect signal transduction, cell migration, differentiation, and tissue organization. The components of the extracellular matrix and their functions during embryonic development in annelids are not well-characterized. With access during the summer months to cocoon-producing Lumbriculus, we used immunological and histological techniques to look for glycosaminoglycans and extracellular matrix proteins in cocoons and embryos. Ponceau S staining of sectioned cocoons showed that the cocoon membrane was proteinaceous. Several proteins ranging in size from 21,000 to 91,000 daltons were also detected in the matrix (jelly) that surrounds embryos within cocoons. The jelly was comprised of sulfated mucopolysaccharides, based on safranin O, alcian blue, and dimethylmethylene blue staining. Incubation of cocoons for 1 to 16 hours with enzymes that degrade glucan sulfate, chondroitin sulfate, and dermatan sulfate showed no differences in alcian blue staining between control and enzyme-treated sections. These results, together with the inability of hyaluronic acid-binding protein to interact with the jelly, suggested the matrix surrounding Lumbriculus embryos is a distinct glycan. In adult worms, epidermal cells in the segments containing reproductive structures stained with safranin O and alcian blue and were elongated compared to epidermal cells in segments without reproductive structures. It is likely that the elongated cells were involved in production and secretion of the jelly during cocoon formation. Immunohistochemistry revealed the presence of laminin and fibronectin in embryos at late stages of development. Future research will explore the relationships between the temporal expression of these extracellular matrix molecules and specific events occurring during embryonic development.
