Figure 2

Overview of spectra acquired within an experiment where changes in ion signals corresponding to PDF were detectable statistically. A) Total average spectrum used to define peaks detected within an experiment. The isotopic distribution with monoisotopic peak at m/z 1972.0 is shown in inset. Peak bins detected using our described criteria are highlighted in blue. B) Pseudogel view after preprocessing of all spectra acquired in a particular replicate experiment. C) Zoomed in pseudogel view at m/z regions containing the isotopically resolved [M + H]⁺ of IPNamide (monoisotopic m/z 1653.9, left panel) and the [M + H]⁺ of PDF (monoisotopic m/z 1972.0, boxed off in orange dashed lines, right panel) and the [M + K]⁺ of PDF (monoisotopic m/z 2010.0, boxed off in blue dashed lines, right panel). Also seen in right panel is the isotopic distribution with monoisotopic peak at m/z 1991.0 (boxed off in the dashed magenta lines), corresponding to the truncated and amidated variant of NPLP13 (QRAamide). Peaks trailing from this distribution observed in the PDF overexpressing flies likely corresponds to the [M + Na]⁺ of PDF (monoisotopic m/z 1994.0, marked by an asterisk) which was not resolved enough in the total average spectrum to be detected as a distinct isotopic distribution. D) Averages of preprocessed spectra within experimental conditions at two m/z regions (red = PDF-null, black = WT, blue = PDF overexpressing). The [M + H]⁺ of IPNamide (left, 95% confidence intervals shown to the left of each peak for clarity), which was found not to vary significantly across conditions (Kruskal-Wallis ANOVA raw p-value = 0.22), is compared with the [M + H]⁺ of PDF (right), which was detected to be significantly different across the three conditions (Bonferroni-adjusted p-value = 0.0017).