Formation of the prismatic layer in the freshwater bivalveHyriopsis cumingii: the feedback of crystal growth on organic matrix

Abstract

The squeezing hypothesis and the organic frameworks preformation hypothesis propose two different mechanisms to explain the interaction between organic frameworks and crystals during biomineralization of the prismatic layer of the mollusk shell. In this study, we began to study Hyriopsis cumingii shell formation and discover that this species seemed to follow the squeezing hypothesis. During the formation of the aragonite prismatic layer in the freshwater bivalve H. cumingii, we found that crystal growth was involved in controlling initiation of formation of the interprismatic organic membranes. First, newly formed crystals were embedded in the periostracum. Next, the interprismatic organic membranes of the prismatic layer were produced via squeezing between neighboring crystals. The organic matrix secreted by the mantle continuously self‐assembled into the interprismatic organic membranes as the crystals grew. In the mature stage, the interprismatic organic membranes were shaped by crystal growth. These findings provide evidence to support the squeezing hypothesis and add to the existing knowledge about interactions that occur at the organic–inorganic interfaces during mollusk shell biomineralization.

A Novel Matrix Protein Hic31 from the Prismatic Layer of Hyriopsis Cumingii Displays a Collagen-Like Structure

“…During the formation of prismatic layer, the organic matrix performs as an organic layer, where newly-formed crystals are embedded. Following this, the inter-prismatic organic membrane of the prismatic layer is produced by squeezing between neighboring crystals [ 47 ]. The hic31 may play key roles in this process.…”

Nacre morphology and chemical composition in Atlantic winged oyster Pteria colymbus (Röding, 1798)

“…Nacre tablet morphology was characterized with a JEOL 7600F ultra high resolution field emission scanning electron microscope (FESEM). Samples were coated with Au/Pd and processed at a 1-30 kV acceleration voltage (Ren et al, 2009;Liu & Li, 2015).…”

Hcprismatin-14 of Hyriopsis cumingii, a novel matrix protein is crucial for framework recognition and crystal deposition during prismatic layer formation

“…The prismatic layer is a transitional structure, which initially nucleates and grows vertically on the periostracum, forming a base for nacre tablet deposition. It was originally thought that the mature prismatic layer comprised competitively growing prisms, with prisms growing together but being separated by an organic sheath (Liu and Li, 2015). Follow-up experiments showed that a single prism could be further subdivided into nano-sized subgrains after enzymatic hydrolysis (Dauphin, 2003).…”

“…Hic31 is specificity expressed in the mantle edge and acts as a framework protein during prismatic layer formation (Liu et al, 2015b). Previous studies showed the prismatic layer of freshwater mollusks comprised aragonite crystal, which was distinct from the calcite prismatic layer of seawater shellfish (Liu and Li, 2015). Prismatic layer matrix proteins are also involved in pearl formation, and their expression is increased significantly before regular nacre deposition and is usually negatively correlated with pearl quality (Inoue et al, 2011;Liu et al, 2015a;Liu et al, 2015b;Blay et al, 2018;Jin et al, 2019a;Le Luyer et al, 2019).…”