Distance measurements via the morphogen gradient of Bicoid in Drosophila embryos
1 State Key Laboratory of Brain and Cognitive Science Institute of Biophysics Chinese Academy of Sciences 15 Datun Road Beijing 100101, China
2 Graduate School of the Chinese Academy of Sciences Beijing 100049, China
3 Divisions of Biomedical Informatics Cincinnati Children's Research Foundation 3333 Burnet Avenue Cincinnati, OH 45229, USA
4 Developmental Biology Cincinnati Children's Research Foundation 3333 Burnet Avenue Cincinnati, OH 45229, USA
5 Department of Biomedical Engineering University of Cincinnati Cincinnati, OH 45221, USA
BMC Developmental Biology 2010, 10:80 doi:10.1186/1471-213X-10-80Published: 2 August 2010
Patterning along the anterior-posterior (A-P) axis in Drosophila embryos is instructed by the morphogen gradient of Bicoid (Bcd). Despite extensive studies of this morphogen, how embryo geometry may affect gradient formation and target responses has not been investigated experimentally.
In this report, we systematically compare the Bcd gradient profiles and its target expression patterns on the dorsal and ventral sides of the embryo. Our results support a hypothesis that proper distance measurement and the encoded positional information of the Bcd gradient are along the perimeter of the embryo. Our results also reveal that the dorsal and ventral sides of the embryo have a fundamentally similar relationship between Bcd and its target Hunchback (Hb), suggesting that Hb expression properties on the two sides of the embryo can be directly traced to Bcd gradient properties. Our 3-D simulation studies show that a curvature difference between the two sides of an embryo is sufficient to generate Bcd gradient properties that are consistent with experimental observations.
The findings described in this report provide a first quantitative, experimental evaluation of embryo geometry on Bcd gradient formation and target responses. They demonstrate that the physical features of an embryo, such as its shape, are integral to how pattern is formed.