title: A role for polyglucans in a model sea urchin embryo cellular interaction.
abstract: The enzymatic activities of commercially prepared glycosidases were verified by direct chemical assays using defined substrates and fixed and live sea urchin (Lytechinus pictus) embryos to determine if a model cellular interaction of interest to developmental biologists for over a century (interaction of archenteron tip and roof of the blastocoel) was mediated by glycans. Glycosidases (active and denatured) were incubated with microdissected archenterons and blastocoel roofs in a direct assay to learn if their enzymatic activities could prevent the normal adhesive interaction. Of the five glycosidases tested only β-amylase (an exoglycosidase) immediately inhibited the interaction at relatively low unit activity. α-Amylase (an endoglycosidase) had no measurable effect, while other glycosidases (α-glucosidase, β-glucosidase, β-galactosidase) only substantially inhibited adhesion after a 12-h incubation. We demonstrated that the five glycosidases were active (not inhibited) in the presence of embryo materials, and that cleaved sugars could be detected directly after incubation of some enzymes with the embryos. The biochemical purity of the enzymes was examined using gel electrophoresis under denaturing conditions, and the absence of contaminating proteases was confirmed using Azocoll™ substrate. As we cannot entirely rule out the presence of minor contaminating enzymatic activities, only inhibitions of adhesion after very short incubations with enzyme were considered significant and biologically relevant. Although glycans in indirect experiments have been implicated in mediating the interaction of the tip of the archenteron and roof of the blastocoel, to our knowledge, this is the first study that directly implicates polyglucans with terminal 1,4-linked glucose residues in this adhesive event.
authors.affiliation: Center for Cancer and Developmental Biology,California State University,18111 Nordhoff Street,Northridge,California 91330-8303,USA.
authors.forename: Suprita
authors.initials: S
authors.lastname: Singh
authors.affiliation: Center for Cancer and Developmental Biology,California State University,18111 Nordhoff Street,Northridge,California 91330-8303,USA.
authors.forename: Eddie
authors.initials: E
authors.lastname: Karabidian
authors.affiliation: Center for Cancer and Developmental Biology,California State University,18111 Nordhoff Street,Northridge,California 91330-8303,USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kandel
authors.affiliation: Center for Cancer and Developmental Biology,California State University,18111 Nordhoff Street,Northridge,California 91330-8303,USA.
authors.forename: Stan
authors.initials: S
authors.lastname: Metzenberg
authors.affiliation: Department of Chemistry and Biochemistry,California State University,18111 Nordhoff Street,Northridge,California 91330-8262,USA.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Carroll
authors.affiliation: Center for Cancer and Developmental Biology,California State University,Northridge,18111 Nordhoff Street,Northridge,California 91330-8303,USA.
authors.forename: Steven B
authors.initials: SB
authors.lastname: Oppenheimer
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D004625:Embryo, Nonmammalian / Q000166:cytology* / Q000378:metabolism*; D005775:Gastrula / Q000166:cytology; D005936:Glucans / Q000378:metabolism*; D012617:Sea Urchins / Q000196:embryology*; D000520:alpha-Glucosidases / Q000378:metabolism; D001614:beta-Amylase / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: D005936:Glucans; D001614:beta-Amylase; D000520:alpha-Glucosidases; D001617:beta-Glucosidase; D001616:beta-Galactosidase