1. Physics of Living Systems
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A mechanism for hunchback promoters to readout morphogenetic positional information in less than a minute

  1. Jonathan Desponds
  2. Massimo Vergassola  Is a corresponding author
  3. Aleksandra M Walczak
  1. University of California San Diego, United States
  2. École Normale Supérieure, France
Research Article
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Cite this article as: eLife 2020;9:e49758 doi: 10.7554/eLife.49758


Cell fate decisions in the fly embryo are rapid: hunchback genes decide in minutes whether nuclei follow the anterior/posterior developmental blueprint by reading out positional information in the Bicoid morphogen. This developmental system is a prototype of regulatory decision processes that combine speed and accuracy. Traditional arguments based on fixed-time sampling of Bicoid concentration indicate that an accurate readout is impossible within the experimental times. This raises the general issue of how speed-accuracy tradeoffs are achieved. Here, we compare fixed-time to on-the-fly decisions, based on comparing the likelihoods of anterior/posterior locations. We found that these more efficient schemes complete reliable cell fate decisions within the short embryological timescales. We discuss the influence of promoter architectures on decision times and error rates, present concrete examples that rapidly readout the morphogen, and predictions for new experiments. Lastly, we suggest a simple mechanism for RNA production and degradation that approximates the log-likelihood function.

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Author details

  1. Jonathan Desponds

    Physics Department, University of California San Diego, La Jolla, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7112-3217
  2. Massimo Vergassola

    Physics Department, University of California San Diego, La Jolla, United States
    For correspondence
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7212-8244
  3. Aleksandra M Walczak

    Laboratoire de Physique Theorique, École Normale Supérieure, Paris, France
    Competing interests
    Aleksandra M Walczak, Reviewing editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2686-5702


National Science Foundation (PoLS Grant 1411313)

  • Massimo Vergassola

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Michael B Eisen, University of California, Berkeley, United States

Publication history

  1. Received: June 28, 2019
  2. Accepted: July 29, 2020
  3. Accepted Manuscript published: July 29, 2020 (version 1)


© 2020, Desponds 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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