title: A glycoprotein in shells of conspecifics induces larval settlement of the Pacific oyster Crassostrea gigas.
abstract: Settlement of larvae of Crassostrea gigas on shell chips (SC) prepared from shells of 11 different species of mollusks was investigated. Furthermore, the settlement inducing compound in the shell of C. gigas was extracted and subjected to various treatments to characterize the chemical cue. C. gigas larvae settled on SC of all species tested except on Patinopecten yessoensis and Atrina pinnata. In SC of species that induced C. gigas larvae to settle, settlement was proportionate to the amount of SC supplied to the larvae. When compared to C. gigas SC, all species except Crassostrea nippona showed lower settlement inducing activities, suggesting that the cue may be more abundant or in a more available form to the larvae in shells of conspecific and C. nippona than in other species. The settlement inducing activity of C. gigas SC remained intact after antibiotic treatment. Extraction of C. gigas SC with diethyl ether (Et2O-ex), ethanol (EtOH-ex), and water (Aq-ex) did not induce larval settlement of C. gigas larvae. However, extraction of C. gigas SC with 2N of hydrochloric acid (HCl-ex) induced larval settlement that was at the same level as the SC. The settlement inducing compound in the HCl-ex was stable at 100°C but was destroyed or degraded after pepsin, trypsin, PNGase F and trifluoromethanesulfonic acid treatments. This chemical cue eluted between the molecular mass range of 45 and 150 kDa after gel filtration and revealed a major band at 55 kDa on the SDS-PAGE gel after staining with Stains-all. Thus, a 55 kDa glycoprotein component in the organic matrix of C. gigas shells is hypothesized to be the chemical basis of larval settlement on conspecifics.
authors.affiliation: Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Nagasaki, Japan.
authors.forename: Hebert Ely
authors.initials: HE
authors.lastname: Vasquez
authors.affiliation: Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Nagasaki, Japan.
authors.forename: Kyotaro
authors.initials: K
authors.lastname: Hashimoto
authors.affiliation: Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Nagasaki, Japan.
authors.forename: Asami
authors.initials: A
authors.lastname: Yoshida
authors.affiliation: Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Nagasaki, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Hara
authors.affiliation: Department of Pediatric Infectious Disease, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
authors.forename: Chisato Chris
authors.initials: CC
authors.lastname: Imai
authors.affiliation: Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Nagasaki, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kitamura
authors.affiliation: Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Nagasaki, Japan.
authors.forename: Cyril Glenn
authors.initials: CG
authors.lastname: Satuito
mesh_terms: D000704:Analysis of Variance; D060105:Animal Shells; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002850:Chromatography, Gel; D049896:Crassostrea / Q000187:drug effects* / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D000431:Ethanol / Q000494:pharmacology; D004986:Ether / Q000494:pharmacology; D005612:Freeze Drying; D006023:Glycoproteins / Q000494:pharmacology*; D006358:Hot Temperature; D006851:Hydrochloric Acid / Q000494:pharmacology; D007814:Larva / Q000187:drug effects / Q000502:physiology; D010140:Pacific Ocean; D010434:Pepsin A / Q000494:pharmacology; D012996:Solutions; D013045:Species Specificity; D013696:Temperature; D014357:Trypsin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D006023:Glycoproteins; D012996:Solutions; D004986:Ether; D000431:Ethanol; D014357:Trypsin; D010434:Pepsin A; D006851:Hydrochloric Acid