title: Biosilica formation in spicules of the sponge Suberites domuncula: synchronous expression of a gene cluster.
abstract: The formation of spicules is a complicated morphogenetic process in sponges (phylum Porifera). The primmorph system was used to demonstrate that in the demosponge Suberites domuncula the synthesis of the siliceous spicules starts intracellularly and is dependent on the concentration of silicic acid. To understand spicule formation, a cluster of genes was isolated. In the center of this cluster is the silicatein gene, which codes for the enzyme that synthesizes spicules. This gene is flanked by an ankyrin repeat gene at one side and by a tumor necrosis factor receptor-associated factor and a protein kinase gene at the other side. All genes are strongly expressed in primmorphs and intact animals after exposure to silicic acid, and this expression is restricted to those areas where the spicule formation starts or where spicules are maintained in the animals. Our observations suggest that in S. domuncula a coordinated expression of physically linked genes is essential for the synthesis of the major skeletal elements.
authors.affiliation: Institut für Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Johannes Gutenberg-Universität, Duesbergweg 6, D-55099 Mainz, Germany.
authors.forename: Heinz C
authors.initials: HC
authors.lastname: Schröder
authors.forename: Sanja
authors.initials: S
authors.lastname: Perovic-Ottstadt
authors.forename: Vladislav A
authors.initials: VA
authors.lastname: Grebenjuk
authors.forename: Sylvia
authors.initials: S
authors.lastname: Engel
authors.forename: Isabel M
authors.initials: IM
authors.lastname: Müller
authors.forename: Werner E G
authors.initials: WE
authors.lastname: Müller
mesh_terms: D000818:Animals; D001483:Base Sequence; D002403:Cathepsins / Q000096:biosynthesis / Q000235:genetics*; D004798:Enzymes / Q000096:biosynthesis / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D008969:Molecular Sequence Data; D012824:Silicic Acid / Q000494:pharmacology*; D047233:Suberites / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure
chemical_list: D004798:Enzymes; D012824:Silicic Acid; D002403:Cathepsins