Extended Data Fig. 8: PCA comparing negative-ion ToF-SIMS spectra from N. suturalis screening pigments with various reference materials.
From: Fossil insect eyes shed light on trilobite optics and the arthropod pigment screen
a, Score plot of an analysis that includes all major eumelanin and pheomelanin peaks in the mass range m/z 48–146 (Supplementary Table 3). b, Associated loadings from PC1 and PC2, with glyphs indicating the ion categories to which each peak is assigned. c, Bar graph comparing the added signal intensities from all peaks in the various ion categories (error bars are ±1 s.d.). In a–c, Nephrotoma sub-cornea (extract), n = 3 measurements; Nephrotoma facet walls (extract), n = 3 measurements; xanthommatin, n = 3 measurements; Sepia eumelanin, n = 3 measurements; Nephrotoma facet walls, n = 3 measurements; Taeniopygia pheomelanin, n = 3 measurements; cysteinylDOPA (cysDOPA) (1:1) pheomelanin, n = 3 measurements; DHI eumelanin, n = 3 measurements; cysteinyldopamine (cysDA) (1:1) pheomelanin, n = 4 measurements; dopamine (DA) eumelanin, n = 4 measurements; DOPA eumelanin, n = 3 measurements.
