The acquisition of specific cell fates in the early embryo is driven by changes in gene regulatory networks that induce differential expression of effector genes to ultimately instruct a specific cell fate. The activation of such effector genes has been well characterised in time for individual genes, but to a much lesser extent in space. Here (p. 3892), Julius Barsi, Eric Davidson and colleagues performed a quantitative transcriptomic analysis of effector gene activation on a genome-wide scale in six cell populations isolated from different regions of pregastrular and early gastrula sea urchin embryos. With this approach, the authors identify a set of effector gene transcripts shared by the different cell populations. Surprisingly, this shared set of genes is not as large as previously thought. Indeed, the authors show that spatially distinct populations in the early embryo actually display profound differences in effector gene expression long before morphological differences in cell types can be distinguished. This study sheds light on the mechanistic essence of embryonic differentiation and provides a large-scale transcriptomic dataset, a rich resource for the developmental community.
- © 2015. Published by The Company of Biologists Ltd