Precision and scaling in morphogen gradient read-out.
Morphogen gradients infer cell fate as a function of cellular position. Experiments in Drosophila embryos have shown that the Bicoid (Bcd) gradient is precise and exhibits some degree of scaling. We present experimental results on the precision of Bcd target genes for embryos with a single, double or quadruple dose of bicoid demonstrating that precision is highest at mid-embryo and position dependent, rather than gene dependent. This confirms that the major contribution to precision is achieved already at the Bcd gradient formation. Modeling this dynamic process, we investigate precision for inter-embryo fluctuations in different parameters affecting gradient formation. Within our modeling framework, the observed precision can only be achieved by a transient Bcd profile. Studying different extensions of our modeling framework reveals that scaling is generally position dependent and decreases toward the posterior pole. Our measurements confirm this trend, indicating almost perfect scaling except for anterior most expression domains, which overcompensate fluctuations in embryo length.
de Lachapelle
Aitana Morton
AM
Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland.
Bergmann
Sven
S
D000818:Animals; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism*; D008954:Models, Biological; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism*
D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D015534:Trans-Activators; C056478:bcd protein, Drosophila