Fig. 2

Comparative single-metabolite analysis between ARPE-19 cells and eyecups. (A) Linear regression analysis of mean single-metabolite abundance from ARPE-19 cells and eyecups from LC–MS metabolomics analysis. Metabolite abundances are −log10 transformed and normalised to the total metabolite abundance for each sample. Pink indicates high average abundance and blue indicates low average abundance. R2 = 0.577, P-value = 8.35 × 10−27. (B) Volcano plot of ARPE-19 metabolite fold-change relative to eyecups. 17.4% of metabolites with Log2 fold-changes < −1 and −Log10 P values > 1.3 (P < 0.05) were marked blue for the lower threshold, while 12.9% of metabolites with Log2 fold-changes > 1 and −Log10 P values > 1.3 (P < 0.05) were marked red for the upper threshold. Scatterplot and volcano plot were produced using the R package ggplot2.