title: A novel role for dpp in the shaping of bivalve shells revealed in a conserved  molluscan developmental program.
abstract: During the molluscan evolution leading to the bivalves, the single dorsal shell was doubled. To elucidate the molecular developmental basis underlying this prominent morphological transition, we described the cell cleavage and expression patterns of three genes, brachyury, engrailed, and dpp in the Japanese spiny oyster Saccostrea kegaki, and examined the function of dpp in this species. The cleavage pattern of the S. kegaki embryo was nearly the same as the previously described pattern of other bivalve species, suggesting that the pattern itself is highly important for the establishment or the maintenance of the bivalve body plan. The expression pattern of a brachyury homolog in S. kegaki (SkBra) was similar to the pattern in gastopods even at the single cell level despite the deep divergence of gastropods and bivalves. Engrailed and dpp were previously found to be expressed around the shell anlagen in gastropods. Like that of gastropods, an engrailed homolog in S. kegaki (SkEn) was found to be expressed around the shell anlagen. However, the dpp homologin S. kegaki (SkDpp) was expressed only in the cells along the dorsal midline. ZfBMP4 treatment experiments revealed the importance of dpp in establishing the characteristic shape of the bivalve shell anlagen.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Koryu
authors.initials: K
authors.lastname: Kin
authors.forename: Shota
authors.initials: S
authors.lastname: Kakoi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Wada
mesh_terms: D000818:Animals; D005075:Biological Evolution; D049872:Bivalvia / Q000196:embryology* / Q000235:genetics*; D001757:Blastomeres / Q000187:drug effects; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000494:pharmacology; D019070:Cell Lineage; D004305:Dose-Response Relationship, Drug; D004625:Embryo, Nonmammalian; D015870:Gene Expression / Q000187:drug effects; D017403:In Situ Hybridization; D008954:Models, Biological; D008974:Mollusca / Q000196:embryology* / Q000235:genetics*; D011994:Recombinant Proteins / Q000494:pharmacology; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism
chemical_list: D055415:Bone Morphogenetic Protein 4; D011994:Recombinant Proteins