Proteomic insights into collagen remodeling of the calipash in Chinese soft-shelled turtle () under challenge: Implications for nutritional quality and oxidative stress response.

The calipash, a collagen-rich tissue in , undergoes structural degradation during infection, compromising its economic value. This study investigates the underlying collagen alterations. Turtles were challenged with , and samples were collected at 0 h, 6 h, 1d, 3d, 6d, and 10d post-infection. Results showed progressive collagen degradation, peaking at 10d. Early infection increased collagen content, type I collagen proportion, and collagen-related gene expression, but these declined over time. Essential amino acids decreased, while non-essential amino acids (e.g., glycine, proline) increased. iTRAQ proteomics identified 517 differentially expressed proteins (227 up-, 290 down-regulated), including collagen metabolism regulators (ITGB4, TIMP2, LTBP1 up; COL6A6, FKBP7, COL28A1 down). Protein network analysis revealed ECM stabilization and oxidative stress regulation balances collagen turnover. These findings indicated that modulates collagen biosynthesis and degradation under stress, altering collagen structure and mitigating oxidative damage.