However, currently, there is no specific 3′ UTR sequence element known that is functionally important during the OET. Examples include translational activation or degradation of mRNAs mediated by sequence elements in 3′ untranslated regions (3′ UTRs) which are recognized and bound by small non-coding RNAs and/or RNA-binding proteins (RBPs) (Vasudevan et al, 2006 Radford et al, 2008 Giraldez, 2010). Some of the general post-transcriptional mechanisms that regulate gene expression later in embryogenesis at the ‘maternal-to-zygotic transition’ (MZT) could potentially also control the OET. Remarkably, mature germ cells are transcriptionally silent, and reprogramming into totipotency during the OET occurs in the absence of transcription in all studied animals (Davidson, 1989 Evsikov et al, 2006). Although this process is one of the most fundamental events in biology, little is known about the molecular mechanisms that regulate this so-called oocyte-to-embryo transition (OET). Immediately after fertilization, the zygote reorganizes the entirety of its cellular components to become a mitotically dividing totipotent cell (Stitzel & Seydoux, 2007 Evsikov & Evsikova, 2009 Tadros & Lipshitz, 2009). Synopsisįertilization of the egg starts a new life cycle. Our data also indicate that endogenous siRNAs but not miRNAs promote mRNA clearance during the OET. Our data suggest a mechanism in which the pol圜 motif and binding partners direct degradation of maternal mRNAs. We show that orthologs of human pol圜-binding protein specifically bind this motif. Transgenic reporter assays demonstrated that this pol圜 motif is required and sufficient for mRNA degradation after fertilization. Sequence analysis revealed a statistically highly significant presence of a pol圜 motif in the 3′ untranslated regions of most of these degraded mRNAs. We discovered a first wave of degradation in which thousands of mRNAs are cleared shortly after fertilization. This represents a first comprehensive gene expression atlas during the OET in animals. Here, we quantify and analyze transcriptome-wide, expression of mRNAs and thousands of proteins in Caenorhabditis elegans oocytes, 1-cell, and 2-cell embryos. Furthermore, specific molecular mechanisms that regulate gene expression during OET are largely unknown. However, expression of both RNAs and proteins during the OET has not been comprehensively assayed. The oocyte-to-embryo transition (OET) is thought to be mainly driven by post-transcriptional gene regulation.

Crack f4 transcription