the formation of the bicoid morphogen gradient requires protein movement from anteriorly localized mrna形态bicoid梯度的形成需要从先前地本地化的信使rna蛋白质运动.pdf

The Formation of the Bicoid Morphogen Gradient Requires Protein Movement from Anteriorly Localized mRNA 1. ˇ ˇ 2. 3 1 3,4 Shawn C. Little , Gasper Tkacik , Thomas B. Kneeland , Eric F. Wieschaus , Thomas Gregor * 1 Howard Hughes Medical Institute, Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America, 2 Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America, 3 Joseph Henry Laboratories of Physics, Princeton University, Princeton, New Jersey, United States of America, 4 Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America Abstract The Bicoid morphogen gradient directs the patterning of cell fates along the anterior-posterior axis of the syncytial Drosophila embryo and serves as a paradigm of morphogen-mediated patterning. The simplest models of gradient formation rely on constant protein synthesis and diffusion from anteriorly localized source mRNA, coupled with uniform protein degradation. However, currently such models cannot account for all known gradient characteristics. Recent work has proposed that bicoid mRNA spatial distribution is sufficient to produce the observed protein gradient, minimizing the role of protein transport. Here, we adapt a novel method of fluorescent in situ hybridization to quantify the global spatio-temporal dynamics of bicoid mRNA particles. We determine that .90% of all bicoid mRNA is continuously present within the anterior 20% of the embryo. bicoid mRNA distribution along the body axis remains nearly unchanged despite dynamic mRNA translocation from the embryo core to the c