2. D V High [Dorsal] Low [Dorsal] No Dorsal Graded Dorsal Concentration Created by Mother Hierarchy of Gene Action in D/V Patterning Mesoderm Genes Neuroectoderm Genes Non-neural Genes D/V GenesBasic Tissue Types Controlled by Embryo

3. = Mesoderm= Non-Neural Ectoderm= Neuroectoderm Epidermal Genes Dpp Neuronal Genes AS-C RhoVentral Epidermal Genes Neural Genes Twist Mesodermal Genes Snail Neural Genes Brk, Sog Dorsal Genes

4. Dorsal meso neuro epi snail dpp “sog” sog dpp

5. dpp versus sog Expression sog dpp

6. DA Dorsal Region Cell Inside Outside OnOff Repressor From Mother N Nucleus Regulatory Region Coding Region Nucleus Dorsal or Lateral Region Cell Inside Outside Dpp Receptor Sog Signal Relay OnOff Non-neural genes (e.g. dpp) OnOff Neural genes (e.g. AS-C) dpp mRNA No Dorsal Dpp Protein Dpp versus Sog Function

7. Mesodermal Genes Neuronal Genes = Mesoderm= Non-Neural Ectoderm= Neuroectoderm Dpp Sog dpp- versus sog- Mutants X Neuronal Genes Epidermal Genes

8. Mesodermal Genes = Mesoderm= Non-Neural Ectoderm= Neuroectoderm dpp- Mutant Neuronal Genes Sog

9. dpp- Mutant

10. Mesodermal Genes Neuronal Genes = Mesoderm= Non-Neural Ectoderm= Neuroectoderm Dpp Sog sog- Mutant X Neuronal Genes Epidermal Genes

11. Mesodermal Genes = Mesoderm= Non-Neural Ectoderm= Neuroectoderm Dpp Neuronal Genes Epidermal Genes sog- Mutant

13. The Default State of Ectoderm is Neural

14. Sog diffuses and patterns the dorsal region The Players Dpp: A signal that promotes dorsal fates Sog: A secreted inhibitor of Dpp Tolloid = Tld: A protease that cleaves and destroys Sog

15. Dorsal Ventral Tld Low BMP Hi BMP BMP Sog Non-neural Ectoderm Amnioserosa Sog diffuses and patterns the dorsal region

16. A Sog protein gradient forms dorsally Epi Neuro Meso A P V D sog RNA/ Sog Protein

17. Sog protein/dpp RNA Tld limits Sog accumulation dorsally WTDf(tld)

18. Sog Creates a BMP activity gradient dorsally SogDpp VD [Sog] 1) A dorsal Sog gradient is created by a ventral source and dorsal sinks for Sog. Relative BMPActivity 2) A reciprocal BMP activity gradient forms. 3) Dorsal region is subdivided into two domains. Non-neural Ectoderm A.S. race

19. Dpp diffuses and patterns the ventral region - High levels of Dpp signaling in dorsal cells represses all neural genes - Low levels of Dpp diffuse ventrally - Some neural genes are more sensitive than others to Dpp repression (e.g., ind is more sensitive than msh) - Differential sensitivity to Dpp repression creates pattern in the neural region (the least sensitive gene, msh, can be expressed closest to Dpp source)

20. = Mesoderm= Non-Neural Ectoderm= Neuroectoderm High Low None [Dorsal] High Low None Dpp Non-neural genes Neural genes Dorsal Subdivision of the Neuroectoderm Neuronal genes Msh Ind Vnd

21. Drosophila Neuroectoderm Mouse Neural Tube Sonic Hh BMPs MsxNkx2.2Gsh Dorsal Dpp ind msh vnd dpp Patterning the Neuroectoderm in Flies and Mice

22. ind vnd msh D V Ventral Dominant Repression

23. vnd Dpp signaling represses ind more effectively than msh mshind Dpp X ind

24. ECT NE MES 1 3 2 BrkDpp st2-brk Dpp signaling represses ind more effectively than msh

25. Sog Dpp VD [Sog] [Dpp] Relative BMPActivity 2) A BMP repression gradient forms within the neuroectoderm -> Three rows of neuroblasts. mshindvnd Neuroectoderm 1) A Sog gradient creates an inverse BMP activation gradient dorsally -> Non-neural Ectoderm vs Amnioserosa. Non-neural Ectoderm A.S. race Reciprocal Patterning of the Ectoderm by Sog and Dpp

26. BMP signaling in the neuroectoderm of flies and vertebrates