The impact of ART-relevant in vitro maturation on active translation in oocytes and zygotes

Assisted reproductive technology (ART) has become an indispensable tool in fertility treatment. Most ART patients respond normally to controlled ovarian stimulation, however some may benefit from the alternative method of oocyte in vitro maturation (IVM), recognized but still underdeveloped method with limited results. As oocytes undergo the transcriptionally silent phase of meiosis, protein synthesis is an important regulator of oocyte development. Here, we have modelled and compared the clinically relevant IVM simulation with in vivo conditions in mouse oocytes and zygotes. We apply clinically relevant conditions on the mouse model system with aim to uncover the differences in selective recruitment of stored maternal transcripts by the oocyte and zygote translation machinery. Every sample type was collected in quadruplicates: (in vitro matured denuded oocytes=IVM, in vitro matured cumulus-oocyte complexes=COC, in vivo matured oocytes=IVO, in vitro matured and fertilized pronuclear zygotes=IMZ, in vivo matured and fertilized pronuclear zygotes=IVZ) We performed total RNA isolation followed by polysome fractionation as well as collected unfractionated total RNA in respective samples. We performed differential gene expression analysis between in vitro and in vivo maturation conditions from obtained RNA-seq data in oocytes and zygotes