2010/03/29 by Julien Dubuis, Alexander H. Morrison, Dubuis, Julien +5
Biochemistry, Genetics and Molecular Biology · #Advanced Fluorescence Microscopy Techniques #Cell Image Analysis Techniques #FOS: Biological sciences #Gene Regulatory Network Analysis #Quantitative Methods (q-bio.QM)
paper · pdf · doi:10.48550/arxiv.1003.5572
openalex publication_date 2010/03/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In multicellular organisms, patterns of gene expression are established in response to gradients of signaling molecules. During fly development in early Drosophila embryos, the Bicoid (Bcd) morphogen gradient is established within the first hour after fertilization. Bcd acts as a transcription factor, initiating the expression of a cascade of genes that determine the segmentation pattern of the embryo, which serves as a blueprint for the future adult organism. A robust understanding of the mechanisms that govern this segmentation cascade is still lacking, and a new generation of quantitative measurements of the spatio-temporal concentration dynamics of the individual players of this cascade are necessary for further progress. Here we describe a series of methods that are meant to represent a start of such a quantification using Bcd as an example. We describe the generation of a transgenic fly line expressing a Bcd-eGFP fusion protein, and we use this line to carefully analyze the Bcd concentration dynamics and to measure absolute Bcd expression levels in living fly embryos using two-photon microscopy. These experiments have proven to be a fruitful tool generating new insights into the mechanisms that lead to the establishment and the readout of the Bcd gradient. Generalization of these methods to other genes in the Drosophila segmentation cascade is straightforward and should further our understanding of the early patterning processes and the architecture of the underlying genetic network structure.