A chitin-binding domain-containing gene is essential for shell development in the mollusc Tritia

Area of Science:

• Developmental biology
• Biomineralization
• Marine biology

Background:

• Mollusc shells exhibit remarkable diversity in form and function.
• The molecular mechanisms underlying shell formation are not well understood.
• Shell development involves a shell epithelium secreting a chitinous membrane and coordinating biomineral deposition.

Purpose of the Study:

• To investigate the genetic basis of shell development in the gastropod mollusc Tritia (formerly Ilyanassa).
• To characterize the role of the 2d micromere in shell and non-shell structure formation.
• To identify novel genes involved in mollusc shell biogenesis.

Main Methods:

• Comparative transcriptome analysis between wild-type and 2d ablated Tritia embryos.
• Identification of shell-specific and non-shell specific genes.
• Functional analysis using morpholino knockdown of candidate genes, specifically ToChitin BD.

Main Results:

• Eight shell-specific and five non-shell specific genes were identified.
• Morpholino knockdown of the shell-specific gene ToChitin-binding domain-containing (ToChitin BD) resulted in significant shell defects.
• ToChitin BD knockdown embryos exhibited disorganized chitinous periostracal membranes with loss of defined edges and peroxidase gradients.

Conclusions:

• The gene ToChitin BD plays a critical role in mollusc shell formation, particularly in maintaining the integrity of the chitinous periostracal membrane.
• This study provides new molecular insights into the complex process of biomineralization in gastropod shells.
• The identified genes offer potential targets for future research into shell evolution and development.