We also work on the formation of the Bicoid gradient from its mRNA gradient, as suggested by a recent publication [1]. We model the active quasi-random transport of bcd mRNA from the anterior pole (along a non-polar cortical microtubules network), forming a complex with the mRNA-binding protein Staufen, in a pure diffusive way. Establishment of the Bcd protein gradient arises by local translation from the non-localized and evolving mRNA gradient. We use a simple and general formalism for the modeling of morphogen gradient formation which allows to obtain explicit analytical solutions in the 1D case. We can also estimate diffusive parameters. The model is also being compared to static source models (without mRNA transport) involving delocalization of the source (step- and Gaussian source).

Recommended reading

• Introduction to Systems Biology, Uri Alon
• Developmental Biology, Gilbert
• Review on A-P patterning in the Drosophila embryo [2][3]
• Precision and Scaling of the Bicoid gradient [4][5][6][7][8][9]
• Temperature robustness of the Bicoid gradient [10]

References

1. pmid = 19168676
2. Anterior-posterior patterning in the Drosophila embryo Advances in Developmental Biology and Biochemistry, 2002, 12, 155-204

3. Ephrussi A and St Johnston D. Seeing is believing: the bicoid morphogen gradient matures. Cell 2004 Jan 23; 116(2) 143-52. pmid:14744427.
5. Gregor T, Bialek W, de Ruyter van Steveninck RR, Tank DW, and Wieschaus EF. Diffusion and scaling during early embryonic pattern formation. Proc Natl Acad Sci U S A 2005 Dec 20; 102(51) 18403-7. doi:10.1073/pnas.0509483102 pmid:16352710.
6. Bergmann S, Sandler O, Sberro H, Shnider S, Schejter E, Shilo BZ, and Barkai N. Pre-steady-state decoding of the Bicoid morphogen gradient. PLoS Biol 2007 Feb; 5(2) e46. doi:10.1371/journal.pbio.0050046 pmid:17298180.
7. Gregor T, Wieschaus EF, McGregor AP, Bialek W, and Tank DW. Stability and nuclear dynamics of the bicoid morphogen gradient. Cell 2007 Jul 13; 130(1) 141-52. doi:10.1016/j.cell.2007.05.026 pmid:17632061.
8. Gregor T, Tank DW, Wieschaus EF, and Bialek W. Probing the limits to positional information. Cell 2007 Jul 13; 130(1) 153-64. doi:10.1016/j.cell.2007.05.025 pmid:17632062.
9. He F, Wen Y, Deng J, Lin X, Lu LJ, Jiao R, and Ma J. Probing intrinsic properties of a robust morphogen gradient in Drosophila. Dev Cell 2008 Oct; 15(4) 558-67. doi:10.1016/j.devcel.2008.09.004 pmid:18854140.
10. Lucchetta EM, Lee JH, Fu LA, Patel NH, and Ismagilov RF. Dynamics of Drosophila embryonic patterning network perturbed in space and time using microfluidics. Nature 2005 Apr 28; 434(7037) 1134-8. doi:10.1038/nature03509 pmid:15858575.
11. Houchmandzadeh B, Wieschaus E, and Leibler S. Establishment of developmental precision and proportions in the early Drosophila embryo. Nature 2002 Feb 14; 415(6873) 798-802. doi:10.1038/415798a pmid:11845210.