Transcription templated assembly of the nucleolus in the C. elegans embryo.

How membraneless organelles like nucleolus assemble within cells is not well understood. Recent experiments suggest that transcription of ribosomal RNA actively drives nucleolar assembly. Our proposed model of active transcription-templated assembly quantitatively accounts for the rapid kinetics observed in early worm embryos at different developmental stages. Further, it predicts a scaling of the time to assembly with the volume of the nucleus that is confirmed by experimental data. This work describes how active processes such as transcription can control the placement and timing of assembly of membraneless organelles.