Lightsheet Micrograph of Zebrafish Embryo.

eLife paper on ZGA timing: activator-repressor competition

Our study demonstrating how repressors (histones) and activators (transcription factors) jointly control transcription in the zebrafish embryo is now available online: Competition between histone and transcription factor binding regulates the onset of transcription in zebrafish embryos. Joseph et al. eLife (2016)

Competition Model

In this study, lead by Shai Joseph (Vastenhouw Lab) and carried out collaboratively with the Shevchenko and Zaburdaev lab, we could quantitatively address a long-standing question: how is the timing at which transcription starts in embryos controlled?

By a combination of quantitative, molecular, and functional techniques, we found that the two most prominent hypotheses, the "depleted repressor" and the "increasing activator" models, can be unified in a competition model. Here, repressing histones and activating transcription factors go head-to-head competing for access to DNA target sites.

Additionally, the nuclear-to-cytoplasmic ratio - often defined in the number of genomes in an embryo - resurfaced as a key concept, though in the form of a volume ratio between cell nuclei and overall cytoplasm. While the global concentration of not DNA-bound histones did not change at the time of transcription onset, we detected a marked decrease in the concentration of not DNA-bound histones specifically within cell nuclei.

 

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BioRxiv: Histone and transcription factor binding competition

A preprint for our latest work is now on BioRxiv: “Competition between histone and transcription factor binding regulates the onset of transcription in zebrafish embryos”. The lead author of this study is Shai, with lots of support from within the Vastenhouw lab as well as the Zaburdaev (MPI-PKS) and Shevchenko labs (MPI-CBG).

You can go and read the preprint here: http://biorxiv.org/content/early/2017/04/13/125716

Example images from the smFISH pipeline presented in Stapel et al. 2015

Methods Article in ‘Development’

We are happy to post about our lab’s recent publication in Development. The article describes how to label and analyze single mRNA molecules, within single cells, at different stages of the zebrafish embryo’s development. With this technique, we hope to open new avenues into gene expression patterns and cellular differentiation programs.

The project was chiefly driven Carine Stapel, currently a PhD student in the Vastenhouw Lab. Carine developed the experimental protocol. The associated, freely available image analysis and quantification pipeline was developed in collaboration with Gene Myer’s research group as well as the Scientific Computing Facility. In fact, all work was done in-house at the MPI-CBG, demonstrating the institute’s wide array of qualifications as well as its collaborative spirit.

The article and protocol are available from Development, and the article also contains the analysis pipeline in its Supplementary Information. Article Page at Development

Automated detection and quantification of single RNAs at cellular resolution in zebrafish embryos

L. Carine StapelBenoit LombardotColeman BroaddusDagmar KainmuellerFlorian JugEugene W. MyersNadine L. Vastenhouw;