Anterior-Posterior Polarity in Drosophila:Important concepts:1. Maternal effect genes: bicoid, nanos, caudal, maternal hunchback2. Gap genes (expressed by the embryo (zygote)): giant, hunchback, Kruppel, etc.3. Pair-rule genes: hairy, even-skipped, paired, etc.4. Segment polarity genes: engrailed, wingless, hedgehog, etc. 5. Hox genes: Antennapedia, Ultrabithorax, etc.From: Genetic Control of Segmentation in Drosophila: The Maternal Legacyby Dr. William Brook Department of Medical Biochemistry University of Calgaryhttp://www.ucalgary.ca/UofC/eduweb/virtualembryo/D_m_segment_I.html6. Enhancers: a regulatory DNA sequence that controls the transcription of a gene. Example: the enhancer that controls the expression of even-skipped in the stripe 2 region.A. Modularity of enhancers (different stripes of even-skipped gene expression are regulated by different enhancers). B. Combinatorial regulation of enhancers by repressors and activators of transcription: even-skipped stripe 2 enhancer is activated by the transcription factors bicoid and hunchback and repressed by giant and Kruppel. The combined input of these transcription factors results in a single stripe-pattern of transcription from this enhancer (blue line in the figure below). Anterior PosteriorFrom: Genetic Control of Segmentation in Drosophila: The Maternal Legacyby Dr. William Brook Department of Medical Biochemistry University of Calgaryhttp://www.ucalgary.ca/UofC/eduwe
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