GSE208709
Elements of divergence in germline determination in closely related sea urchin species
Evolutionary transitions enable the wide diversity in life histories of plants and animals. This is particularly germane in the development of the germline in which fitness is a direct readout of evolutionary change. Here, we focused on two distinct sea urchin species who shared a common ancestor 50 million years ago. Even though they both rely on inherited mechanisms to specify their germ line, the integration of stage-matched scRNA seq datasets from these two sea urchins revealed, amongst others, a broader expression of Nanos2 in Lytechinus variegatus (Lv) compared to Strongylocentrotus purpuratus (Sp). In Sp, Nanos2 mRNA expression is highly restricted to the PGCs by a lability element in its 3'UTR. This element is lacking in Lv Nanos2, explaining how this mRNA more broadly accumulates in the Lv embryos. We discovered that the Lv Nanos2 3'UTR instead leads to a germline specific translation of the protein. The results emphasize that regulatory mechanisms resulting in germline diversity rely less on transcriptional regulation and more on post-transcriptional and post-translational restrictions of key gene products, such as Nanos2. Overall design: Developmental time points in the sea urchin Lytechinus variegatus and integration with the sea urchin Strongylocentrotus purpuratus dataset