Zebrafish embryonic explants undergo genetically encoded self-assembly
Abstract
Embryonic stem cell cultures are thought to self-organize into embryoid bodies, able to undergo symmetry-breaking, germ layer specification and even morphogenesis. Yet, it is unclear how to reconcile this remarkable self-organization capacity with classical experiments demonstrating key roles for extrinsic biases by maternal factors and/or extraembryonic tissues in embryogenesis. Here, we show that zebrafish embryonic tissue explants, prepared prior to germ layer induction and lacking extraembryonic tissues, can specify all germ layers and form a seemingly complete mesendoderm anlage. Importantly, explant organization requires polarized inheritance of maternal factors from dorsal-marginal regions of the blastoderm. Moreover, induction of endoderm and head-mesoderm, which require peak Nodal-signaling levels, is highly variable in explants, reminiscent of embryos with reduced Nodal signals from the extraembryonic tissues. Together, these data suggest that zebrafish explants do not undergo bona-fide self-organization, but rather display features of genetically encoded self-assembly, where intrinsic genetic programs control the emergence of order.
Data availability
All data generated and analyzed in the manuscript are provided as Source Data Files. The Custom Script used has been uploaded as Source code 1.
Article and author information
Author details
Funding
H2020 European Research Council (MECSPEC742573)
- Carl-Philipp Heisenberg
Austrian Academy of Sciences
- Alexandra Schauer
European Molecular Biology Organization (850-2017)
- Diana Pinheiro
Human Frontier Science Program (LT000429/2018-L2)
- Diana Pinheiro
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All animal experiments in this study were performed in strict accordance with the guidelines of the Ethics and Animal Welfare Committee (ETK) in Austria. The respective approval number that covers the performed experiments is 66.018/0010-WF/II/3b/2014.
Copyright
© 2020, Schauer et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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