A gradient of bicoid protein in Drosophila embryos

Max-Planck-Institut für Entwicklungsbiologie, Abteilung III Genetik, Tübingen, Federal Republic of Germany.
Cell (Impact Factor: 32.24). 08/1988; 54(1):83-93. DOI: 10.1016/0092-8674(88)90182-1
Source: PubMed


The maternal gene bicoid (bcd) organizes anterior development in Drosophila. Its mRNA is localized at the anterior tip of the oocyte and early embryo. Antibodies raised against bcd fusion proteins recognize a 55-57 kd doublet band in Western blots of extracts of 0-4 hr old embryos. This protein is absent or reduced in embryonic extracts of nine of the 11 bcd alleles. The protein is concentrated in the nuclei of cleavage stage embryos. It cannot be detected in oocytes, indicating temporal control of bcd mRNA translation. The bcd protein is distributed in an exponential concentration gradient with a maximum at the anterior tip, reaching background levels in the posterior third of the embryo. The gradient is probably generated by diffusion from the local mRNA source and dispersed degradation.

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Available from: Wolfgang Driever, May 16, 2014

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Article: A gradient of bicoid protein in Drosophila embryos

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    • "Similar patterns of broad subdivision followed by shortrange refinement are found during the specification of the vertebrate neural crest by reiterated rounds of extracellular signaling [22]; in the formation of segmented muscle precursors (somites) by FGF and Notch followed by short range Ephrin activity [23] [24]; the dorsal-ventral patterning of the Drosophila body axis, first by a gradient of NFκB activity (also called Dorsal) and then by members of the BMP family of secreted signaling molecules [25] [26]; and also in the fruit fly, the patterning of the anteriorposterior (AP) axis by gradients of diffusible transcription factors within the shared cytoplasm of the nuclear syncytium [15] [27] [28]. These examples and others illustrate a common theme where long range signaling gradients subdivide a large field into smaller domains, within which the patterned expression of secondary factors establishes elaborated patterns (Fig. 1B). "
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    ABSTRACT: In pattern-forming developmental systems, cells commonly interpret graded input signals, known as morphogens. Morphogens often pattern tissues through cascades of sequential gene expression steps. Such a multi-tiered structure appears to constitute suboptimal use of the positional information provided by the input morphogen because noise is added at each tier. However, the conventional theory neglects the role of the format in which information is encoded. We argue that the relevant performance measure is not solely the amount of information carried by the morphogen, but the amount of information that can be accessed by the downstream network. We demonstrate that quantifying the information that is accessible to the system naturally explains the prevalence of multi-tiered network architectures as a consequence of the noise inherent to the control of gene expression. We support our argument with empirical observations from patterning along the major body axis of the fruit fly embryo.
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    • "The concentration of Bicoid protein is higher near the anterior pole of the embryo and its local concentration decreases as the distance to the anterior pole increases. This is called the Bicoid protein gradient [2] [4]. Recently, bicoid mRNA gradients along the anteroposterior axis of the embryo of Drosophila have been observed [15], clarifying our current views about Drosophila early development. "
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    ABSTRACT: We show that mRNA diffusion is the main morphogenesis mechanism that consistently explains the establishment of Bicoid protein gradients in the embryo of Drosophila, contradicting the current view of protein diffusion. Moreover, we show that if diffusion for both bicoid mRNA and Bicoid protein were assumed, a steady distribution of Bicoid protein with a constant concentration along the embryo would result, contradicting observations. © 2014 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.
    Comptes Rendus Biologies 10/2014; 337(12). DOI:10.1016/j.crvi.2014.09.004 · 0.98 Impact Factor
    • "The model took into account three major processes essential for embryo development: synthesis of proteins, their diffusion between nuclei and degradation. The same approach was used in (Driever and Nusslein-Volhard, 1988) to explain the dynamics of the Bicoid maternal protein in D. melanogaster embryo. It is known as the synthesis-diffusion-degradation model (Gregor et al., 2007). "
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    ABSTRACT: Motivation: We propose the third-order model equation of the Jeffreys type for concentrations of gap gene proteins in order to take into account particle inertia. Gap genes are responsible for formation of body segments in Drosophila melanogaster embryo during its early development. Usually the expression of the genes is described by the model of protein transport based on conventional diffusion equation. However, the model is known to govern the Brownian (non-inertial) motion of particles; hence, it is hardly applicable to the description of protein transport. Results: Analysis of the Jeffreys-type equation results in the necessary condition for the problem to be well-posed. Application of the Jeffreys-type equation with non-linear terms to description of the dynamics of gap gene network demonstrates better fitting to experimental data than the conventional model. Availability and implementation: Implementation of solver algorithms and the software are freely available from: https://github.com/wswgG/solver-for-the-Jeffreys-type-equations-system .
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