Pizza Science and Beyond… with Vastenhouwlab

 

About once a month, DIPP PhD students gather to share & discuss their research with their peers in an informal atmosphere, along with pizza. Pizza Science and Beyond (PSB) is an initiative from the Student representatives of the DIPP predocs.

This year, both Mate (back in March) and Ksenia (this August) gave chalk talks featuring lab’s signature ZGA curve on a board.

How is transcription organised in the nucleus? How does the chromatin become open? Does Mate really have a wikipedia page?… and many other questions were discussed.

 

Photos by Shady El-Husseiny

EMBO Workshop@MPI-CBG: Maternal-Zygotic Transition

From 23rd to 26th April, the MPI-CBG hosted the first international meeting exclusively dedicated to the Maternal-Zygotic Transition (MZT). Under the title "Awakening of the genome: The maternal-to-zygotic transition", a jam-packed meeting program was presented under the umbrella of the EMBO event series.

Focusing on genome activation allowed a first-ever platform for the MZT community. Participants from all over the world gathered to showcase an extensive range of techniques, approaches, and biological questions. Plenty of new and unpublished data made it exciting, a meeting size of ~150 participants meant that everyone could be easily approached, and the wish for a repeat meeting was voiced several times.

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.