I found this review on the Maternal-to-Zygotic transition (MZT), describing how developmental control switches from maternally deposited RNAs to zygotic expression. I was struck by figure 1, and the apparent difference between viviparous and oviparous life histories. My maybe naive question is, Could the sharp increase of zygotic expression reflect conflict between the maternal and zygotic genomes?

waves of zygotic gene expression MZT review

  • $\begingroup$ In this figure only the Mouse is viviparous. I don't have a clear sense of what you mean by "competition." In sexually reproducing species, like these five, fully one half of the zygotic genome is identical to the maternal genome. I suggest that you try thinking about like this: the main purpose of oogenesis is to create a cell that will provide everything that the zygote needs following fertilization. The eggs are getting loaded up with proteins and mRNA the zygote will use until its own genes get transcribed. In mice and worms it only takes 1-3 cell divisions for the embryo to take over. $\endgroup$ – mdperry Apr 19 '15 at 1:35
  • $\begingroup$ What seems so striking to me is that the length of a single cell cycle is so drastically long in the viviparous species. That tells us that if your mom lays eggs then those first cell cycles are incredibly fast, which really means that oogenesis is stuffing those eggs full of DNA polymerase and dNTP's. $\endgroup$ – mdperry Apr 19 '15 at 1:37

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