Evidence for abortive transcription in early ZGA. (A) Analysis of read density across transcripts, comparing results for zygotic and maternally deposited transcripts. The fraction of reads mapping to genes transcribed during NC 7–9 are plotted across the binned transcript bodies (red). For comparison, the fraction of reads mapping to 100 equal-sized cohorts of maternal transcripts are plotted across their binned transcribed bodies (gray). (B) Distributions of the normalized read densities plotted in A. At the left are the cumulative distributions, indicating results for the zygotic transcripts (red) and maternal cohorts (gray). Dashed line indicates median. At the right is the distribution of median values, plotting in red the median value of the zygotic cumulative distribution. (C,D) As in A,B but for genes that become activated in NC 9–10 embryos. (E,F) As in A,B but for genes that become activated in syncytial-blastoderm embryos. (G,H) As in A,B but for genes that become activated in cellularized-blastoderm embryos.
