Fig. 3

Orthogonal projections to latent structures discriminate analysis (OPLS-DA) analysis of gills after the treatment of different alkali concentrations. The LC-MS spectra was used to measure the OPLS-DA score. (A) indicated the OPLS-DA analysis between 0 mmol/L vs. 4 mmol/L; (B) indicated the OPLS-DA analysis between 0 mmol/L vs. 8 mmol/L; (C) indicated the OPLS-DA analysis between 0 mmol/L vs. 12 mmol/L