6 and 8 November, 2006 Chapter 18 Gene Regulation During Development.
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6 and 8 November, 2006 Chapter 18 Gene Regulation During Development
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Transcript of 6 and 8 November, 2006 Chapter 18 Gene Regulation During Development.
6 and 8 November, 2006
Chapter 18
Gene Regulation During Development
Overview• Differences in cell type are fundamentally differences in gene expression.• These expression differences are often monitored using microarray hybridization.• Differential gene expression is initiated by asymmetrical mRNA distribution, cell-
cell contact, or by diffusible signals.• Gradients of signaling molecules can give location information to cells.• Asymmetrically distributed mRNAs use the cytoskeleton for localization.• Drosophila embryogenesis is a well-understood system of animal development.• A morphogen gradient controls dorsal-ventral orientation in Drosophila.• Asymmetrically distributed mRNAs control anterior-posterior orientation and
ultimately segmentation.• Segmentation also depends on the interplay of regulators at the control regions of
genes.• Bioinformatics tools are useful in identifying genes that are developmentally
regulated.
Signaling Differentiation
Transducing the Signal
Regualtion in a
Morphogen Gradient
Regulation by Asymmetrically Distributed mRNA
Regulation by Asymmetrically Distributed mRNA
Polar Cytoskeletal Elements
Regulation by Cell-cell contact in B. subtilis
Regulation by Cell-cell contact in Animal
Development
Regulation by Cell-cell contact in Animal
Development
Morphogen Gradient
Drosophila Development
Spätzle-Toll create a gradient of Dorsal in nuclei.
Transcriptional response to the Dorsal Gradient
Snail keeps rhomboid off in cells of the mesoderm.
Polar Distribution of
bicoid and oksar in
Drosophila Embryos
Bicoid regulates orthodenticle and zygotic hunchback.
Maternal hunchback mRNA is evenly distributed, but translationally repressed by the posteriorly
concentrated nanos.
The hunchback gradient regulates gap genes as a transcriptional repressor.
Gap genes direct the
expression of pair-rule genes.
Gap genes direct the
expression of pair-rule
genes.
Bioinformatics and the identification of enhancers.
Competition and Quecnching in the eve enhancer
Repression of eve-3 and eve-4 enhancers by hunchback and knirps.
Enhancer autonomy requires short-range repression.
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