New quantitative data show that the Bicoid morphogen gradient is generated from a dynamic localized source and that protein gradient formation requires protein movement along the anterior-posterior axis

A Abu-Arish

A Arvey

A Ephrussi

A Ochoa-Espinosa

A Pare

A Porcher

A Raj

A Spirov

A. B Cubitt

A. M Femino

A. N Becalska

A. N Boettiger

B Cha

B Houchmandzadeh

C Sample

C Wagner

C. C Fowlkes

Claude Desplan

D Ferrandon

D St Johnston

E Lecuyer

E. M Lucchetta

Eric F. Wieschaus

F Alves

F. J Salles

G Frigerio

G Struhl

Gašper Tkačik

I Hecht

J Deng

J Dubuis

J. M Kugler

L Wolpert

L. M Liberman

M Coppey

M Schuh

O Grimm

P Surdej

R Campbell

R Namba

R Rivera-Pomar

R. P Wharton

S Bergmann

Shawn C. Little

T Berleth

T Gregor

T Lecuit

T Nagai

T. T Weil

Thomas B. Kneeland

Thomas Gregor

V. E Foe

W Driever

Y. F Wu

English

PubMed

Crossref

PLoS Biology

The Formation of the Bicoid Morphogen Gradient Requires Protein Movement from Anteriorly Localized mRNA

The Bicoid morphogen gradient directs the patterning of cell fates along the anterior-posterior axis of the syncytial Drosophila embryo and serves as a paradigm of morphogen-mediated patterning. The simplest models of gradient formation rely on constant protein synthesis and diffusion from anteriorly localized source mRNA, coupled with uniform protein degradation. However, currently such models cannot account for all known gradient characteristics. Recent work has proposed that bicoid mRNA spatial distribution is sufficient to produce the observed protein gradient, minimizing the role of protein transport. Here, we adapt a novel method of fluorescent in situ hybridization to quantify the global spatio-temporal dynamics of bicoid mRNA particles. We determine that >90% of all bicoid mRNA is continuously present within the anterior 20% of the embryo. bicoid mRNA distribution along the body axis remains nearly unchanged despite dynamic mRNA translocation from the embryo core to the cortex. To evaluate the impact of mRNA distribution on protein gradient dynamics, we provide detailed quantitative measurements of nuclear Bicoid levels during the formation of the protein gradient. We find that gradient establishment begins 45 minutes after fertilization and that the gradient requires about 50 minutes to reach peak levels. In numerical simulations of gradient formation, we find that incorporating the actual bicoid mRNA distribution yields a closer prediction of the observed protein dynamics compared to modeling protein production from a point source at the anterior pole. We conclude that the spatial distribution of bicoid mRNA contributes to, but cannot account for, protein gradient formation, and therefore that protein movement, either active or passive, is required for gradient formation

Shawn C Little

Thomas B Kneeland

Eric F Wieschaus

Directory of Open Access Journals

The formation of the Bicoid morphogen gradient requires protein movement from anteriorly localized mRNA.

Little Shawn C.

Tkačik Gašper

Kneeland Thomas B.

Wieschaus Eric F.

Gregor Thomas

Public Library of Science (PLOS)

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The Formation of the Bicoid Morphogen Gradient Requires Protein Movement from Anteriorly Localized mRNA

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Public Library of Science (PLOS)