#BSDBGenSoc2020 final part 
The results show that gastruloids are organized and that this organization corresponds to that of the embryo; see go.nature.com/3d0lB6b for details.
One surprising observation here is the differentiation trajectories of NMPs and, in particular the gene expression sequence of somitogenesis: Bra ->Tbx6 -> Uncx4.1.
We had observed this before but here, w/ more genes, it is striking.
Surprisingly, despite scaled and coordinated gene expression, there are no somites, though somite specific genes uncx4.1, pax3 are expressed anterior to PSM genes.
Surprisingly, if you place gastruloids in Matrigel as they undergo somitogenesis, cells oscillate and segment go.nature.com/3d0lB6b;
A beautiful recent preprint @jvveenvliet (R. Hermann lab) biorxiv.org/content/10.110… has similar results though they go further and show that Matrigel upregulates ECM receptors.
This apparent decoupling between mechanics and chemistry was presciently pointed out by Alan Turing and appears to be a characteristic of Developing organisms
It is unlikely that this uncoupling would have been revealed by Genetics and shows the value of these multicellular engineering approaches
In summary, #gastruloids represent a model for early mammalian development that, together with genetics, allows us to probe the potential and strategies of cells.
People talk much aboiut GRNs maybe this approach will allow us to start talking and exploring Cell Regulatory Networks (CRN) which encompass genes but have their own rules and principles.
In the end, I cannot close without making a reference to V. Hamburger’s famed statement, which reigns true, though rather than a teacher I would say it is a reference.
If what we want is to get at how cells build embryos, I believe that these new approaches are and will be key but, always, with a reference to the embryo (w/o forgetting which embryo)
I want to thank members of my group that during the years have helped develop this system: @PeterBeej @da40cambs @nmoris Kerim Anlas, Txell Vinyoles, @ShlomitEdri and of course Tina Balayo and many undergraduates, masters and summer students.
Also our collaborators at @EPFL @Duboule and @TheLutolfLab specially @muggi_and L. Beccari and @_Hubrecht
@SusannevdBrink @AlexandervanOu1 @annionna and funders
@SusannevdBrink @AlexandervanOu1 @annionna and funders
Protocols are available on line but we shall be happy to provide further information upon request. And now I am happy to answer any questions.
