Spatial and temporal patterns of Krüppel gene expression in early Drosophila embryos

Knipple, Douglas C.; Seifert, E; Rosenberg, Urs B.; Preiss, Anette; Jäckle, Herbert

doi:10.1038/317040a0

Cited by 169 publications

(74 citation statements)

References 24 publications

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“…The transcription of Bicoid target genes has been observed as early as cycle 10 ( Knipple et al, 1985;Tautz et al, 1987;Jaeger et al, 2007). At this stage, for certain Bicoid lifetime values, the gradient might be far from its steady state (Fig.…”

Section: When Is the Gradient Utilised?mentioning

confidence: 99%

Modelling the Bicoid gradient

2010

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SummaryMorphogen gradients provide embryonic tissues with positional information by inducing target genes at different concentration thresholds and thus at different positions. The Bicoid morphogen gradient in Drosophila melanogaster embryos has recently been analysed quantitatively, yet how it forms remains a matter of controversy. Several biophysical models that rely on production, diffusion and degradation have been formulated to account for the observed dynamics of the Bicoid gradient, but no one model can account for all its characteristics. Here, we discuss how existing data on this gradient fit the various proposed models and what aspects of gradient formation these models fail to explain. We suggest that knowing a few additional parameters, such as the lifetime of Bicoid, would help to identify and develop better models of Bicoid gradient formation.

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Section: When Is the Gradient Utilised?mentioning

confidence: 99%

Modelling the Bicoid gradient

2010

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“…Development 137 (10) Finkelstein and Perrimon, 1990); 2 (Gao et al, 1996); 3 (Lemke and Schmidt-Ott, 2009); 4 (Tautz et al, 1987); 5 (Tautz, 1988); 6 (Olesnicky et al, 2006); 7 (Knipple et al, 1985); 8 (Gaul and Jäckle, 1987); 9 (Hülskamp et al, 1990);10 (Rothe et al, 1989); 11 (Rothe et al, 1994), note that knrl is expressed similarly to kni but weaker in its posterior domain, and that posterior knrl expression remains unchanged in Torso-deficient embryos; 12 (Eldon and Pirrotta, 1991); 13 (Kraut and Levine, 1991); 14 (Brönner and Jäckle, 1991); 15 ; 16 (Mlodzik and Gehring, 1987a); 17 (Mlodzik and Gehring, 1987b); 18 (Pignoni et al, 1990).…”

Section: Research Articlementioning

confidence: 99%

Maternal activation of gap genes in the hover flyEpisyrphus

et al. 2010

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The metameric organization of the insect body plan is initiated with the activation of gap genes, a set of transcription-factor-encoding genes that are zygotically expressed in broad and partially overlapping domains along the anteroposterior (AP) axis of the early embryo. The spatial pattern of gap gene expression domains along the AP axis is generally conserved, but the maternal genes that regulate their expression are not. Building on the comprehensive knowledge of maternal gap gene activation in Drosophila, we used loss- and gain-of-function experiments in the hover fly Episyrphus balteatus (Syrphidae) to address the question of how the maternal regulation of gap genes evolved. We find that, in Episyrphus, a highly diverged bicoid ortholog is solely responsible for the AP polarity of the embryo. Episyrphus bicoid represses anterior zygotic expression of caudal and activates the anterior and central gap genes orthodenticle, hunchback and Krüppel. In bicoid-deficient Episyrphus embryos, nanos is insufficient to generate morphological asymmetry along the AP axis. Furthermore, we find that torso transiently regulates anterior repression of caudal and is required for the activation of orthodenticle, whereas all posterior gap gene domains of knirps, giant, hunchback, tailless and huckebein depend on caudal. We conclude that all maternal coordinate genes have altered their specific functions during the radiation of higher flies (Cyclorrhapha).

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“…Initially, the Kr gene was identified on the basis of its segmentation defect. Analysis of the expression of the gene, however, revealed a complex pattern throughout embryogenesis (13,14). The functional relevance of the Kr expression in the different regions and tissues of the embryo has not yet been elucidated in detail.…”

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confidence: 99%