Fig. 2: Neurons but not neuroblasts upregulate rare-codon-enriched expression.

A Images of GFP-rare^b protein (green in merged image) and mRNA (magenta in merged image) in WL3 brains. Scale bar 10 μm. Dashed outline indicates NB. B GFP-rare^b protein expression relative to w¹¹¹⁸ controls in indicated cell types in WL3 brains (see Methods). Two biological replicates. One-way ANOVA performed followed by Tukey’s multiple comparisons test, p = 0.0002 for both. C Quantification of GFP-rare^b RNA expression relative to w¹¹¹⁸ controls in indicated cell types in WL3 brain (see Methods). Two biological replicates. One-way ANOVA performed followed by Tukey’s multiple comparisons test. NB vs GMC, p = 0.001; NB vs neurons, p < 0.0001; GMC vs neurons, p < 0.0011. D Representative images of GFP-common protein (green in merged image) and mRNA (magenta in merged image) in WL3 brains. Scale bar 10 μm. Dashed outline indicates NB. E Quantification of GFP-common protein expression in indicated cell types relative to w¹¹¹⁸ controls in WL3 brains. Two biological replicates. No significant differences detected by one-way ANOVA. F Quantification of GFP-common RNA expression in indicated cell types relative to w¹¹¹⁸ controls in WL3 brain (see Methods). Two biological replicates. No significant differences detected by one-way ANOVA. G mRNA/protein ratio of GFP-rare^b in each cell type. Relative GFP-rare^b mRNA and protein from E and F are plotted as a ratio of mRNA to protein. H Analysis of codon usage in NBs and neurons from single-cell RNA sequencing data retrieved from Yang et al. 2016 and Berger et al. 2012 (see Methods); highly expressed genes were defined as twofold enriched cell type of interest in both datasets. Expressed genes in each cell type are represented in a violin plot of CAI distribution. “Total” is a plot of all mRNAs in the dataset. Dashed line indicates CAI of GFP-rare^b. A Kolgomorov–Smirnov test was performed to compare the distributions between NBs and neurons (*: p = 0.0173). Source data for B, C, E–H are provided as separate Source Data files. Mean ± SEM plotted on each graph. Precise N values provided in source data file for B, C, E, F.