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Fly Embryonic Patterning Mutants and the Body Plan Formation

This lecture explores the formation of the nose versus tail of a fly, the role of the nervous system, head, thorax, and abdomen in pattern formation. Topics covered include the role of "denticle" hairs, anterior-posterior patterning mutants, dorsal-ventral patterning mutants, segment polarity genes, and the hierarchy of gene action in patterning.

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Fly Embryonic Patterning Mutants and the Body Plan Formation

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  1. LECTURE 6: FORMING THE NOSE VERSUS TAIL OF A FLY

  2. D Tail Skin A P Nervous System (inside) Head Thorax Abdomen “Denticle” Hairs V The Body Plan of a Fly Maggot

  3. Anterior-Posterior Patterning Mutants Dorsal-Ventral Patterning Mutants Fly Embryonic Patterning Mutants

  4. Gap Genes Controlled by Embryo Kruppel Pair-rule Genes even-skipped Segment Polarity Genes Homeotic Genes (e.g., engrailed) (e.g., Bithorax) Hierarchy of Gene Action in A/P Patterning Bicoid Controlled by Mother A P

  5. Bicoid A P Hunchback Knirps 7 6 1 2 3 5 4 Even-skipped Homeotic

  6. 1 2 3 4 5 6 7 even-skipped stripes even-skipped mRNA Stripe 2 OtherStripes Stripe 3 Off On Off On Off On Regulatory Region Coding Region Independent Regulatory Elements Activate even-skipped Expression in Different Stripes

  7. Hb Kni 3 even-skipped stripe 3 Condition for Activating Expression of even-skipped Stripe 3 1. An activator, which is expressed everywhere, must be present. 2. Repressors, Hunchback and Knirps,must be absent.

  8. Dorsal-Ventral Patterning Mutants Dorsal-Ventral Patterning Mutants

  9. Graded Dorsal Concentration D/V Genes Basic Tissue Types D No Dorsal Epidermal Genes Low [Dorsal] Neuronal Genes High [Dorsal] Mesoderm Genes V Created by Mother Controlled by Embryo Hierarchy of Gene Action in D/V Patterning D V

  10. Epidermal Genes Dpp Neuronal Genes Dorsal Genes Brk, Sog AS-C Neural Genes Rho Ventral Epidermal Genes Neural Genes Snail Mesodermal Genes Twist = M e s o d e r m = N e u r o e c t o d e r m = N o n - N e u r a l E c t o d e r m

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