Figure 2.
Method development of pulse injection for fetal labeling
(A) Experimental design for in utero labeling. Fetuses from E14.5 pregnant mice are pulse injected. Heart, liver, and lung tissues are harvested 16 h later and analyzed by mass spectrometry.
(B) Representative MS1 spectra showing heavy amino acid incorporation. The percentage of incorporation is calculated as the fraction of heavy precursor over the total precursor pool (heavy + light).
(C) Incorporation of heavy labeled amino acids into the proteome of heart, liver, and lung tissues using four biological replicates. The median and mean incorporation are 8.6% ± 1.2% and 17.5% ± 0.6%, respectively.
(D) Heatmap showing the Pearson correlation of the light and heavy precursors across the tissues analyzed. Inset: scatterplots of light and heavy peptides show high reproducibility between biological samples.
(E) Principal-component analysis (PCA) of the light and heavy precursors.
(F) Distribution of peptide abundances in log2 showing the subset of nascent peptides (heavy-isotope labeled).