Figure 5

Rescue assay showing that Sbp9 is indispensable for the integrity of scallop root. (a) EGFL₄ partially recovered byssal root integrity. The native byssal root was whitish, and the root became more transparent with EDTA/DTT treatment when compared to the untreated group. The addition of EGFL₄ or Ca²⁺ caused the root to become whitish, while the addition of BSA did not. (b) TEM photographs revealed that the addition of EGFL₄ partially repaired the byssal root. The native byssal root comprises uniform fibers, as shown by the untreated group. EDTA/DTT treatment resulted in the byssal root proteins agglutination together irregularly, and the fibers became loose. The addition of EGFL₄ partially rescued the byssal root integrity, while the addition of BSA did not. The addition of Ca²⁺ partially rescued the fibers cohesive while high electron-dense granules were still presence. (c) FTIR spectra revealed that addition of EGFL₄ is able to partially restore the architecture of the disrupted byssal root by the EDTA/DDT treatment. EDTA/DTT treatment altered the secondary structure of byssal root proteins. The addition of EGFL₄ partially rescued the secondary structure, while the addition of BSA or Ca²⁺ did not.