Quantitative Proteomics Analysis of Duck Eggshell during Biomineralization

Eggshell mineralization is the crucial process for avian and reptile reproduction, meanwhile associated with eggshell quality for commercial interest. Current understanding of eggshell biomineralization is based on intensive studies of few species, especially domestic chicken. A comparison of eggshell proteome among more species could contribute a better comprehension of the biominerlization process and diversifications of the eggshell ultrastructure among birds. In this study, we used isobaric taqs for relative and absolute quantification (iTRAQ) MS/MS to detect proteomics changes in duck eggshell during biominerlization and identified 305 uterine fluid proteins/protein groups (1% FDR) in the eggshell. 191 proteins showed differential abundances during mammillary layer and palisade layer formation (12h eggshell after the ovulation; normal ovulation eggshell). Constitutes of duck eggshell proteome is similar to Chicken and Turkey eggshell. Major eggshell proteins such as Ovotransferrin, Ovostatin, Ovalbumin and Ovomucoid with most abundance have highly expressed (>1.5 fold) during mammillary layer and palisade layer formation, suggested that these protein mainly involved and deposited in the mammillary layer and palisade layer. Several proteins related to the shell mineralization and antimicrobial (e.g. IgA heavy-chain, Lysozyme) also represented a highly differential expression with lower abundance in duck eggshell matrix. However, no duck eggshell-specific proteins had been identified in our result. The number of the identified proteins in duck eggshell is lower than turkey and chicken eggshell due to the low quality reference of duck proteins. Our study showed some well-known eggshell proteins could play a similar roles in duck eggshell during biomeralization.