An electron microscope study of the formation of the periostracum ofMacrocallista maculata

Bevelander, Gerrit; Nakahara, Hiroyuki

doi:10.1007/bf02008075

Cited by 50 publications

(35 citation statements)

References 3 publications

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“…Nucula sulcata [73] and Cerastoderma edule [69], have indicated that some bivalves have two basal cells, we have no positive evidence that this is also true for Neotrigonia. The epithelial cells of the MMF fold are columnar in some bivalves species [71] or cuboidal in most of them [72], [75], but in Neotrigonia they are squamous and very stretched out. The cells lining the inner surface of the OMF are columnar and contribute to the formation of the TL of the periostracum, as in most of the studied bivalves [66], [69], [74], [75] (Figs.…”

Section: Discussionmentioning

confidence: 99%

Early Stage Biomineralization in the Periostracum of the ‘Living Fossil’ Bivalve Neotrigonia

et al. 2014

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A detailed investigation of the shell formation of the palaeoheterodont ‘living fossil’ Neotrigonia concentrated on the timing and manufacture of the calcified ‘bosses’ which stud the outside of all trigonioid bivalves (extant and fossil) has been conducted. Electron microscopy and optical microscopy revealed that Neotrigonia spp. have a spiral-shaped periostracal groove. The periostracum itself is secreted by the basal cell, as a thin dark pellicle, becoming progressively transformed into a thin dark layer by additions of secretions from the internal outer mantle fold. Later, intense secretion of the internal surface of the outer mantle fold forms a translucent layer, which becomes transformed by tanning into a dark layer. The initiation of calcified bosses occurred at a very early stage of periostracum formation, deep within the periostracal groove immediately below the initialmost dark layer. At this stage, they consist of a series of polycyclically twinned crystals. The bosses grow as the periostracum traverse through the periostracal groove, in coordination with the thickening of the dark periostracal layer and until, upon reaching the mantle edge, they impinge upon each other and become transformed into large prisms separated by dark periostracal walls. In conclusion, the initial bosses and the external part of the prismatic layer are fully intraperiostracal. With later growth, the prisms transform into fibrous aggregates, although the details of the process are unknown. This reinforces the relationships with other groups that have the ability to form intraperiostracal calcifications, for example the unionoids with which the trigonioids form the clade Paleoheterodonta. The presence of similar structures in anomalodesmatans and other euheterodonts raises the question of whether this indicates a relationship or represents a convergence. The identification of very early calcification within an organic sheet has interesting implications for our understanding of how shells may have evolved.

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Section: Discussionmentioning

confidence: 99%

Early Stage Biomineralization in the Periostracum of the ‘Living Fossil’ Bivalve Neotrigonia

et al. 2014

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“…This process and subsequent thickening of the periostracum are carried out by the groups of cells lining the groove (Bevelander and Nakahara 1967, Wada 1968, Neff 1972a, Bubel 1973a, b, 1976, Saleuddin 1974, Richardson et al 1981. Assembly of the pellicle membrane appears to take place extracellularly in the groove.…”

Section: Periostracummentioning

confidence: 99%

Biology of the Integument

Bereiter‐Hahn¹,

Matoltsy²,

Richards³

1984

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“…The periostracum of most mollusk species consists of three morphologically distinguishable layers. The observations with the optical microscope revealed that the outer and middle layers are formed within the periostracal groove from the innermost row of cells in the outer mantle fold called basal cells [6–9], and the inner layer is secreted by the mantle epithelium [10,11]. The ultrastructural morphology of the cells and the cellular mechanisms involved in this process were described previously [3,7,12,13].…”

Section: Introductionmentioning

confidence: 98%

“…The observations with the optical microscope revealed that the outer and middle layers are formed within the periostracal groove from the innermost row of cells in the outer mantle fold called basal cells [6–9], and the inner layer is secreted by the mantle epithelium [10,11]. The ultrastructural morphology of the cells and the cellular mechanisms involved in this process were described previously [3,7,12,13]. The middle layer is responsible for the secretion of the outer shell layer with vacuolization and antrum formation in bivalves [14,15].…”

Section: Introductionmentioning

confidence: 99%

Identification and characterization of a matrix protein (PPP‐10) in the periostracum of the pearl oyster, Pinctada fucata

et al. 2013

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The periostracum is a layered structure that is formed as a mollusk shell grows. The shell is covered by the periostracum, which consists of organic matrices that prevent decalcification of the shell. In the present study, we discovered the presence of chitin in the periostracum and identified a novel matrix protein, Pinctada fucata periostracum protein named PPP-10. It was purified from the sodium dodecyl sulfate/dithiothreitol-soluble fraction of the periostracum of the Japanese pearl oyster, P. fucata. The deduced amino acid sequence was determined by a combination of amino acid sequence analysis and cDNA cloning. The open reading frame encoded a precursor protein of 112 amino acid residues including a 21-residue signal peptide. The 91 residues following the signal peptide contained abundant Cys and Tyr residues. PPP-10 was expressed on the outer side of the outer fold in the mantle, indicating that PPP-10 was present in the second or third layer of the periostracum. We also determined that the recombinant PPP-10 had chitin-binding activity and could incorporate chitin into the scaffolds of the periostracum. These results shed light on the early steps in mollusk shell formation.

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An electron microscope study of the formation of the periostracum ofMacrocallista maculata

Cited by 50 publications

References 3 publications

Early Stage Biomineralization in the Periostracum of the ‘Living Fossil’ Bivalve Neotrigonia

Early Stage Biomineralization in the Periostracum of the ‘Living Fossil’ Bivalve Neotrigonia

Biology of the Integument

Identification and characterization of a matrix protein (PPP‐10) in the periostracum of the pearl oyster, Pinctada fucata

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