Extended Data Fig. 2: Characterization of the kinetics of nascent pre-rRNAs.
From: Pre-rRNA spatial distribution and functional organization of the nucleolus
a. The workflow of pulse-chase labelling experiment combined with super-resolution imaging and mass spectrometric (MS) analysis to examine the spatiotemporal distribution of SSU and LSU pre-rRNAs. Imaging tracks the pre-rRNAs outflux, while MS identifies nucleolar proteins associated with different stages of pre-rRNAs at indicated pulse-chase time points. b. Relative pre-rRNAs intensities with radial position from the FC centre over time, quantified from averaged images in Fig. 1h, showing a gradient outflux distribution of nascent rRNAs across nucleoli over time. c. The peak diffusion distance of nascent pre-rRNAs over time (magenta), with the maximum intensity distance of FBL over time (green) as a DFC-localized control. The line is fitted with diffusion distance from DFC images in Fig. 1h. Data are mean ± s.e.m. n = 20 DFC units. VHeLa denotes the relative diffusion velocity of nascent pre-rRNA in HeLa cells. d. Schematic illustrating the pre-rRNA flow across nucleolar sub-compartments. Accompanying with the outward flow, pre-rRNAs are distributed in an increased 3D space, thus with a decreased spatial density. The relative diffusion flux is proportional to the density under the constant linear flow rate (calculated in (c)).
