Fig. 2. Variably penetrant memory of MN chromosome transcription compromise after re-incorporation into a normal nucleus.
a, Example of copy number and transcriptional yield after two generations following a 1:3 mis-segregation in generation 1. The MN sister cell generates two monosomic MN nieces (N1 and N2), whereas the MN cell generates MN daughters (D1 and D2). Only one MN daughter is trisomic because the MN chromatid is poorly replicated. See Extended Data Fig. 2a for the outcome of 2:2 mis-segregations. b, Near-complete loss of transcription of a re-incorporated MN chromosome 5 (magenta) after a 1:3 mis-segregation in generation 1. Shown are the normalized transcription yields as in Fig. 1b. Chromosome 13 (green) underwent a 2:2 mis-segregation in generation 1 and displays transcription recovery after re-incorporation. See also Extended Data Fig. 7. c, Transcription output of 44 re-incorporated MN chromosomes from 37 families using Look-Seq2. Defective indicates a significant reduction in the transcriptional yield (Methods, Supplementary Table 2 and Extended Data Fig. 6). d, Transcription status of the U2OS 2-6-3 transcription reporter (n = 70 from 13 experiments). Defective indicates little or no visible MCP–Halo signal. e, Example of defective MN chromosome transcription after re-incorporation. Grey line indicates the mean and s.e.m. of the FI in controls (normal nuclei; n = 23 LacI reporters; Extended Data Fig. 8a). Red horizontal line indicates minimum detectable value in the controls. Black line indicates reporter transcription in a ruptured MN (no detectable generation 1 signal) that does not reach a normal level after re-incorporation (generation 2). f, Example of full transcription recovery, analysed as in e. Red vertical line indicates the time point of MN nuclear envelope rupture. g, Best single focal plane confocal images from a time-lapse series showing defective transcription after re-incorporation. Green, GFP–H2B; blue triangles, reporter locus; magenta triangles, MS2 reporter expression; open arrowheads, cell that enters the field, providing an adventitious MCP–Halo bleaching control. Scale bar, 5 µm.