Quantifying translation in space and time During development, precise control of gene expression establishes reproducible patterns, leading to the formation of organs at the right time and place. The emergence of developmental patterns has been primarily studied at the transcriptional level, but the fate of these transcripts has received little attention. Dufourt et al. used the SunTag labeling method to image the dynamics of translation of individual messenger RNA (mRNA) molecules in living fruit fly embryos. This work revealed “translation factories”—clusters of mRNA and translation machinery—and heterogeneities in the efficiency of translation between identical mRNAs. Science , abc3483, this issue p. 840