title: Patterns of expression in the matrix proteins responsible for nucleation and growth of aragonite crystals in flat pearls of Pinctada fucata.
abstract: The initial growth of the nacreous layer is crucial for comprehending the formation of nacreous aragonite. A flat pearl method in the presence of the inner-shell film was conducted to evaluate the role of matrix proteins in the initial stages of nacre biomineralization in vivo. We examined the crystals deposited on a substrate and the expression patterns of the matrix proteins in the mantle facing the substrate. In this study, the aragonite crystals nucleated on the surface at 5 days in the inner-shell film system. In the film-free system, the calcite crystals nucleated at 5 days, a new organic film covered the calcite, and the aragonite nucleated at 10 days. This meant that the nacre lamellae appeared in the inner-shell film system 5 days earlier than that in the film-free system, timing that was consistent with the maximum level of matrix proteins during the first 20 days. In addition, matrix proteins (Nacrein, MSI60, N19, N16 and Pif80) had similar expression patterns in controlling the sequential morphologies of the nacre growth in the inner-film system, while these proteins in the film-free system also had similar patterns of expression. These results suggest that matrix proteins regulate aragonite nucleation and growth with the inner-shell film in vivo.
authors.affiliation: Institute of Marine Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Xiang
authors.forename: Jingtan
authors.initials: J
authors.lastname: Su
authors.forename: Guilan
authors.initials: G
authors.lastname: Zheng
authors.forename: Jian
authors.initials: J
authors.lastname: Liang
authors.forename: Guiyou
authors.initials: G
authors.lastname: Zhang
authors.forename: Hongzhong
authors.initials: H
authors.lastname: Wang
authors.forename: Liping
authors.initials: L
authors.lastname: Xie
authors.forename: Rongqing
authors.initials: R
authors.lastname: Zhang
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002119:Calcium Carbonate / Q000737:chemistry*; D003460:Crystallization; D017931:DNA Primers / Q000235:genetics; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D060734:Nacre / Q000096:biosynthesis*; D049911:Pinctada / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman
chemical_list: D017931:DNA Primers; D016326:Extracellular Matrix Proteins; D060734:Nacre; D002119:Calcium Carbonate