Whole transcriptome subcellular profiling of the Xenopus oocyte

Abstract
Starting from a single fertilized oocyte, through manifold of divisions a complex organism is developed that has distinct head-tail (bottom-up), left-right and dorsal-ventral (back-belly) asymmetries. One of the main challenges in developmental biology is to understand how and when these asymmetries are generated and how they are controlled. The African clawed frog (Xenopus laevis) is an ideal model for studies of early development thanks to their very large oocytes. We have developed a unique molecular tomography platform based on qRT-PCR, RNA-seq and UPLC-ESI- MS/MS to measure asymmetric localization of fate determining mRNAs, non-coding RNAs and proteins within the oocyte and among the early stage blastomeres. The first axis called animal- vegetal, is formed during oogenesis and we found mRNA and microRNA gradients determining its formation. First cell division following fertilization producing 2-cell stage embryo forms the left-right, and second cleavage generating 4-cell embryos specifies the dorsal-ventral axis.
http://dx.doi.org/10.1016/j.bdq.2017.02.089