Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Nagasaki, Japan.
Department of Pediatric Infectious Disease, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
PLoS One. 2013 Dec 12;8(12):e82358. doi: 10.1371/journal.pone.0082358. eCollection 2013.
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.
研究了用 11 种不同贝类的贝壳制备的贝壳片（SC）上太平洋牡蛎幼虫的附着情况。此外，还从太平洋牡蛎贝壳中提取了附着诱导化合物，并对其进行了各种处理，以表征该化学信号。除了虾夷扇贝和短石蛏外，太平洋牡蛎幼虫都能附着在所有测试的贝壳片上。在能诱导太平洋牡蛎幼虫附着的贝壳片中，幼虫的附着比例与提供给幼虫的贝壳片数量成正比。与太平洋牡蛎贝壳片相比，除了日本真牡蛎外，所有其他贝类的附着诱导活性都较低，这表明同种和日本真牡蛎贝壳中的幼虫可能更容易接触到或更容易获得这种信号物质。抗生素处理后，太平洋牡蛎贝壳片的附着诱导活性仍然完整。用二乙醚（Et2O-ex）、乙醇（EtOH-ex）和水（Aq-ex）提取太平洋牡蛎贝壳片，均不能诱导太平洋牡蛎幼虫的附着。然而，用 2N 盐酸（HCl-ex）提取太平洋牡蛎贝壳片可诱导幼虫附着，其附着水平与贝壳片相当。HCl-ex 中的附着诱导化合物在 100°C 时稳定，但在胃蛋白酶、胰蛋白酶、PNGase F 和三氟甲磺酸处理后被破坏或降解。该化学信号在凝胶过滤过程中洗脱的分子量范围在 45 和 150 kDa 之间，经染色后 SDS-PAGE 凝胶上显示出 55 kDa 的主要条带。因此，推测太平洋牡蛎贝壳有机基质中的 55 kDa 糖蛋白成分是幼虫附着在同种贝壳上的化学基础。
