Noncanonical Compensation of Zygotic X Transcription in Early Drosophila melanogaster Development Revealed through Single-Embryo RNA-Seq
Figure 2
Polymorphisms distinguish maternal and zygotic expression.
(A) Approximately 70% of genes expressed in the early embryo contained fixed differences between the maternal (w1) and paternal (CantonS) lines, allowing us to partition the expression level for that gene at each time point into those derived from the maternal and paternal chromosomes. (B) We classified genes based on temporal profiles of total mRNA and (where available) mRNA derived from maternal and paternal chromosomes. Maternally deposited transcripts (∼5,000) were expressed at high levels that decay over time and come exclusively from the maternal chromosome. Zygotic transcripts (∼2,000) were not present or were present at very low levels at cycle 10, and transcript levels rose over time with equal contribution from maternal and paternal chromosomes. Approximately 800 transcripts are both maternally deposited and zygotically transcribed. (C) Left, the average proportion of zygotic reads per gene increases over time, accelerating during mid cycle 14. Right, a histogram showing the proportion of zygotic reads over genes for an early and a late stage.