Dynamic changes in sialic acid composition during fertilization and embryogenesis in the Sea Urchin Paracentrotus lividus (P. lividus)

Purpose: The aim of this study was to investigate the dynamic changes in sialic acid composition during embryonic development of the sea urchin Paracentrotus lividus (P. lividus) and to evaluate stage-specific variations in sialic acid composition.Method: Sialic acid variants were analyzed in unfertilized eggs and embryos at the fertilized egg, 4-cell, 128-cell, blastula, gastrula, and pluteus stages using capillary LC–ESI–MS/MS following DMB derivatization. Relative abundances were determined from the peak areas of LC–ESI–MS/MS MRM chromatograms. Statistical differences among developmental stages were evaluated using one-way ANOVA followed by Tukey's multiple comparisons test.Findings: Seven sialic acid species, including Neu5Ac, Neu5Gc, and five O-acetylated derivatives, were identified throughout embryonic development. Neu5Gc was the predominant sialic acid in unfertilized eggs and exhibited a significant reduction immediately after fertilization (P < 0.0001), followed by a transient increase during early cleavage and blastula stages before declining markedly in gastrula and pluteus embryos. Neu5Ac remained relatively stable throughout early development but decreased significantly at the pluteus stage (P < 0.001). Several O-acetylated sialic acid derivatives displayed distinct stage-specific abundance patterns, indicating dynamic remodeling of sialic acid composition during embryogenesis.Conclusion: These findings demonstrate that sialic acid composition is developmentally regulated during P. lividus embryogenesis. The stage-specific alterations in Neu5Gc, Neu5Ac, and their O-acetylated derivatives suggest coordinated regulation of sialylation during early embryonic development and provide a foundation for future studies investigating the functional roles of sialic acid modifications in developmental processes.