Fig. 2

Representative picture showing the areas analyzed by FTIRI in the fourth bifurcated fin ray of the dorsal lobe of the regenerating fin. The two regions assayed after amputation were: proximal-corresponding to the first formed bifurcation after amputation and distal-corresponding to the last segment joint preceding the actinotrichia; (b and c) Representative microphotograph (left) and false color images (right) denoting the topographical distribution of phosphate groups in the proximal and distal areas of the regenerated fin from C and P fins (n = 3) at (b) 5 DPA and (c) 10 DPA time points. The same color scale (0–3) was used for all false color images: white/light pink colors indicate the areas with the highest amount of phosphates, red/orange/yellow indicate the areas with an intermediate amount and black/dark blue shows the areas with the lowest amount of phosphates. The black dotted squares indicate the region where spectra were extracted for the curve fitting analysis; (d–f) Biochemical composition and bone mineralization assessed by FTIRI analysis. Histograms representing band area ratios (d) A₁₆₅₅/A₁₀₂₄, (e) A₁₂₄₀/A₁₀₂₄ and (f) A₁₀₂₄/A₁₀₉₀ are calculated on proximal and distal regions of the regenerating fin from C (n = 3) and P (n = 3) fins at 5 DPA and 10 DPA. Data are presented as mean ± S.D. Different letters over the histograms indicate statistically significant difference among groups. Two-way ANOVA and Tukey’s multiple comparison test are used, and statistical significance was set at p < 0.05.