Influence of the Organic Matrix on Crystal Type in Molluscs

Watabe, Norimitsu; Wilbur, Karl M.

doi:10.1038/188334a0

Cited by 113 publications

(53 citation statements)

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“…Growth of abalone (Haliotis rufescens) nacre. The growth of the red abalone shell has been the subject of considerable study starting in as early as the 1950s with Wada [104,105], continuing with Watabe and Wilbur [106], Bevelander and Nakahara [107] and followed by many others. The work by the UC Santa Barbara group [64,82,[108][109][110][111][112][113][114] represents one of the most comprehensive efforts.…”

Section: Nacreous Shellsmentioning

confidence: 99%

Biological materials: Structure and mechanical properties

Meyers

Chen

Lin

et al. 2008

Progress in Materials Science

2,073

1,129

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Most natural (or biological) materials are complex composites whose mechanical properties are often outstanding, considering the weak constituents from which they are assembled. These complex structures, which have risen from hundreds of million years of evolution, are inspiring Materials Scientists in the design of novel materials.Their defining characteristics, hierarchy, multifunctionality, and self-healing capability, are illustrated. Self-organization is also a fundamental feature of many biological materials and the manner by which the structures are assembled from the molecular level up. The basic building blocks are described, starting with the 20 amino acids and proceeding to polypeptides, polysaccharides, and polypeptides-saccharides. These, on their turn, compose the basic proteins, which are the primary constituents of 'soft tissues' and are also present in most biominerals. There are over 1000 proteins, and we describe only the principal ones, with emphasis on collagen, chitin, keratin, and elastin. The 'hard' phases are primarily strengthened by minerals, which nucleate and grow in a biomediated environment that determines the size, shape and distribution of individual crystals. The most important mineral phases are discussed: hydroxyapatite, silica, and aragonite.Using the classification of Wegst and Ashby, the principal mechanical characteristics and structures of biological ceramics, polymer composites, elastomers, and cellular materials are presented. Selected systems in each class are described with emphasis on the relationship between their structure and mechanical response. A fifth class is added to this: functional biological materials, which have a structure developed for a specific function: adhesion, optical properties, etc.An outgrowth of this effort is the search for bioinspired materials and structures. Traditional approaches focus on design methodologies of biological materials using conventional synthetic 0079-6425/$ -see front matter Ó

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Section: Nacreous Shellsmentioning

confidence: 99%

Biological materials: Structure and mechanical properties

Meyers

Chen

Lin

et al. 2008

Progress in Materials Science

2,073

1,129

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“…Such crystal polymorphism in the two closely situated layers is a highly elaborated phenomenon in the mollusk. In such regulated processes, organic matrices secreted from the mantle epithelia have been suggested to play critical roles (3); the major components of soluble organic matrices are aspartic acid-rich calcium binding proteins (4)(5)(6)(7)(8). Recently, Falini et al (9) and Belcher et al (10) reported that macromolecules extracted from the nacreous shell layers induced aragonite formation in vitro.…”

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confidence: 98%

“…We measured CA activity using the C02-Veronal indicator method (16,17) as follows. Six drops of phenol red, 3 …”

mentioning

confidence: 99%

A carbonic anhydrase from the nacreous layer in oyster pearls.

Miyamoto

Miyashita

Okushima

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

508

414

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It is believed that the polymorphism observed in calcium carbonate crystals, such as aragonite and calcite in mollusk shells, is controlled by organic matrix proteins secreted from the mantle epithelia. However, the fine structures of these proteins are still unknown, and to understand the molecular mechanisms of mineralization process, detailed structural analyses of the organic matrix proteins are essential. For this, we have carried out purification, characterization, and cDNA cloning of nacrein, which is a soluble organic matrix protein in the nacreous layer of oyster pearls.Northern blot analysis showed that the nacrein transcript was specifically expressed in mantle pallial. Analysis of the deduced amino acid sequence revealed that the protein contained two functional domains: one was a carbonic anhydrase and another was a Gly-Xaa-Asn (Xaa = Asp, Asn, or Glu) repeat domain; however, the carbonic anhydrase domain was split into two subdomains with insertion of the Gly-Xaa-Asn repeat domain between them. Our findings suggest that nacrein actually functions as a matrix protein whose repeated Gly-Xaa-Asn domain possibly binds calcium and as a carbonic anhydrase that catalyzes the HCO-formation, thus participating in calcium carbonate crystal formation of the nacreous layer.Crystallization, observed in many organisms, is a genetically regulated process. In the mammal, several factors regulating bone morphogenesis are identified. Osteopontin, an acidic calcium binding protein, is isolated from the mineralized phase of bone (1). Another bone matrix protein, osteocalcin (2), contains 'y-carboxyglutamic acid residues, which participate in calcium binding. In general, the mollusk shell is mainly composed of two layers, a prismatic layer and nacreous layer. Both layers are in the forms of calcium carbonate crystal; however, the prismatic layer forms calcite and the nacreous layer forms aragonite. Such crystal polymorphism in the two closely situated layers is a highly elaborated phenomenon in the mollusk. In such regulated processes, organic matrices secreted from the mantle epithelia have been suggested to play critical roles (3); the major components of soluble organic matrices are aspartic acid-rich calcium binding proteins (4-8). Recently, Falini et al. (9) and Belcher et al. (10) reported that macromolecules extracted from the nacreous shell layers induced aragonite formation in vitro.Pearl oysters (Pinctada fucata) produce pearls inside the shells. Such a pearl is equivalent to the mollusk shell layer, which is composed of the aragonite crystal and organic matrices. Therefore, to isolate the organic matrix protein, we have chosen the pearl as a starting material. Staining with Coomassie brilliant blue and Stains-all (Nacalai Tesque, Kyoto), we have identified a 60-kDa protein that we named nacrein. Analysis of cDNA encoding nacrein revealed that it had a similar domain to carbonic anhydrase (CA). Furthermore, the native nacrein purified from the pearl possessed CA enzymatic activity. To our knowledge, t...

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“…A previous study reported that organic matrices extracted from the nacreous layer induced aragonite crystal formation in vitro (Watabe and Wilbur 1960). Asp residues in the matrix proteins interact with calcium atoms in calcium carbonate.…”

Section: -2 Organic Matricesmentioning

confidence: 99%

“…Previous reports have suggested that the organic matrices in the shell play key roles in regulating crystal nucleation, polymorphy, growth, morphology, and orientation in the calcification process (Lowenstam and Weiner 1989). A previ- ous study reported that organic matrices extracted from the nacreous layer induce the formation of aragonite crystals under ambient conditions (Watabe and Wilbur et al 1960). Another study showed that organic matrices in the mollusc shell contain many Asp residues (Weiner and Hood 1975).…”

Section: Introductionmentioning

confidence: 99%

Studies on the Chemical Structures of Organic Matrices and Their Functions in the Biomineralization Processes of Molluscan Shells

Suzuki¹,

Kogure²,

Nagasawa³

2017

AGri-Biosci. Monogr. (AGBM)

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Keywordscalcium carbonate and an organic matrix. In the course of shell formation, the periostracum, which is not mineralized and covers the external surface of the shell, is formed first; subsequently, the prismatic layer is formed on the periostracum. Finally, the nacreous layer is formed on the prismatic layer (Checa 2000). The nacreous layer is made of tablets of aragonite single crystals. The aragonite crystal compartment in the nacreous layer is sandwiched between sheets of organic matrix. In contrast, the prismatic layer is composed of columnar calcite surrounded by the organic matrix. The calcite crystals, surrounded by the organic framework, are oriented on the c-axis perpendicular to the shell surface.The microstructure of the shell of the limpet, Lottia kogamogai, consists of five distinct layers stacked in Studies on the Chemical Structures of Organic Matrices and Their Functions in the Biomineralization Processes of Molluscan Shells AbstractMolluscan shells protect the soft body from predators and the external environment and consist of calcium carbonate in an organic matrix. The interaction between calcium carbonate and the organic matrix forms the microstructure of the molluscan shell. In this review, we discuss several organic molecules that may be important in the formation of the shell microstructure. The iridescent color of pearls is attributed to the characteristic nacreous microstructure of molluscan shells. The Japanese pearl oyster, Pinctada fucata, is used in pearl aquaculture in Japan. The shell of P. fucata consists of two layers, prismatic and nacreous. Prismalin-14 in the prismatic layer interacts with calcium carbonate and binds to chitin. Pif in the nacreous layer interacts with aragonite crystals and plays important roles in forming the organic framework in a compartment-like structure. In contrast, limpets have a crossed lamellar microstructure in their shells. The organic matrices of limpet shells induce the formation of spindle-like aragonite crystals. Recent studies have increased our understanding of the calcification process of molluscan shells, and the findings can be applied to increase yields of high-quality pearls, lowering the cost and energy of pearl aquaculture.

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Influence of the Organic Matrix on Crystal Type in Molluscs

Cited by 113 publications

References 1 publication

Biological materials: Structure and mechanical properties

Biological materials: Structure and mechanical properties

A carbonic anhydrase from the nacreous layer in oyster pearls.

Studies on the Chemical Structures of Organic Matrices and Their Functions in the Biomineralization Processes of Molluscan Shells

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