Characterization and localization of large sulfated glycoproteins in the extracellular matrix of the developing asteroid Pisaster ochraceus

Abstract

In this study techniques commonly used to extract and purify proteoglycans of vertebrates were applied to the embryo of the asteroid Pisaster ochraceus at the early bipinnaria larva stage, a stage in which extensive cell migration is occurring within the extracellular matrix of the blastocoel. Several large sulfated glycoproteins were isolated and shown to consist of protein cores covalently bound to sulfated polysaccharide chains. The polysaccharide chains consisted primarily of neutral sugars and were not susceptible to glycosaminoglycan-degrading enzymes, suggesting that these were not glycosaminoglycans. The sulfated glycoproteins could be fractionated by electrophoresis on sodium dodecyl sulfate-agarose-acrylamide composite gels. Two types of monoclonal antibodies prepared against isolated extracellular matrix of these embryos reacted with two subsets of bands on Western blots of the composite gels. Staining of sections of the embryos with the antibodies showed that the epitopes that they recognized were located throughout the extracellular matrices of the embryos. That these high molecular weight glycoproteins were located within the extracellular matrix of the embryos suggests that they may be involved in the control of morphogenesis and cellular movement.

Secretory Radial Glia in the Ectoneural System of the Sea Star Asterias rubens (Echinodermata)

“…1996) using an antiserum against the 35 kD carbohydrate binding protein (for review, see Anderson & Wang 1992). The hyaline layer of echinoderms has been the subject of many studies (Holland & Nealson 1978;Cameron & Holland 1983;Campbell & Crawford 1991;Crawford & Crawford 1992; Cerra & Byme 1995.). It consists of several layers of granular and fibrous material which contain glycoproteins, proteoglycans and glucosaminoglycans (Spiegel et al 1989).…”

Synthesis and secretion of molecules exhibiting the HL1 epitope during development of the hyaline layer of the asteroid pisaster ochraceus

“…These include hyaline, proteoglycans, glycosaminoglycans, glycoproteins, laminin, and collagen (Spiegel and Spiegel, 1979;Adelson and Humphreys, 1988;Reimer and Crawford, 1990;Crawford and Crawford, 1992;Crawford et al, 1997). In echinoids studies on the secretion of the glycoprotein hyalin, as well as collagen, fibronectin, and laminin show that these molecules are not all released at fertilization but have distinct spatial and temporal expression patterns that extend for at least 30 h postfertilization (Alliegro et al, 1988;Matese et al, 1997).…”