Developmental Cell
Volume 22, Issue 5, 15 May 2012, Pages 1101-1108
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Short Article
Developmental Milestones Punctuate Gene Expression in the Caenorhabditis Embryo

https://doi.org/10.1016/j.devcel.2012.04.004Get rights and content
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Summary

A fundamental question in developmental biology relates to the connection between morphological stages and their underlying molecular activity. Here we demonstrate that, at the molecular level, embryonic development in five Caenorhabditis species proceeds through two distinct milestones in which the transcriptome is resistant to differences in species-specific developmental timings. By comparing the complete protein-coding transcriptomes of individually timed embryos across ten morphological markers, we found that developmental milestones can be characterized by their expression dynamics and activation of key developmental regulators. This approach led us to discover the nematode phylotypic stage and to show that in chordates and arthropods it is represented as two distinct stages, suggesting that animal body plans might evolve by uncoupling and elaboration on formerly synchronous processes.

Highlights

► We present a developmental gene expression time course across 5 species and 10 stages ► Certain stage transitions show conserved expression even when their durations vary ► These stages display low transcriptional activity, followed by bursts of expression ► We propose that one of these stages is the nematode phylotypic stage

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