Relationship Between Yolk Sac Liquid Crystal Formation and Calcium Transport in Pigeon Egg Yolk Sac Endoderm

Abstract

During the incubation of pigeon eggs, the yolk is transformed from a disordered to an ordered state before being absorbed, and the liquid crystals formed the ordered structure via self-assembly in the yolk. In this study, the relationship between the enzymes (ACPase and Ca-ATPase) and liquid crystal formation within the pigeon endoderm was determined. The results showed that ACPase is critical for transforming the yolk into liquid crystals, which originate mainly from the endoderm. The formation of lamellar structures in the yolk was closely associated with the hydrolytic activity of the enzymes. Additionally, a large amount of Ca-ATPase was expressed in the lamellar structures, indicating modulatory effects of Ca-ATPase on the precipitation of calcium carbonate and appearance of lamellar spherical structures. The liquid crystals containing transport enzymes, which formed as a result of laminarization, serve as reaction sites as well as a reactive source of calcium. The transient receptor potential cation channel subfamily V, member 6 (TRPV6) is an epithelial calcium channel. The present study aimed to elucidate the relationship between yolk sac liquid crystals and calcium transport by investigating the regulatory mechanisms underlying TRPV6 gene expression in the pigeon endoderm. The pattern of expression of TRPV6 observed in this study suggests that yolk sac liquid crystals participate in calcium transport in the endoderm.