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LECTURE 10: BRAIN VERSUS SKIN DEVELOPMENT IN MICE AND MEN

LECTURE 10: BRAIN VERSUS SKIN DEVELOPMENT IN MICE AND MEN. Evolutionary Conservation of Neural Induction. Inverted-brate Hypothesis. Dpp. dpp. msh. ind. vnd. Dorsal. BMPs. Msx. Gsh. Nkx2.2. Mouse Neural Tube. Sonic Hh. Patterning the Neuroectoderm in Flies and Mice.

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LECTURE 10: BRAIN VERSUS SKIN DEVELOPMENT IN MICE AND MEN

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  1. LECTURE 10: BRAIN VERSUS SKIN DEVELOPMENT IN MICE AND MEN

  2. Evolutionary Conservation of Neural Induction Inverted-brate Hypothesis

  3. Dpp dpp msh ind vnd Dorsal BMPs Msx Gsh Nkx2.2 Mouse Neural Tube Sonic Hh Patterning the Neuroectoderm in Flies and Mice DrosophilaNeuroectoderm

  4. BMP signaling in the neuroectoderm of flies and vertebrates

  5. Furrow Photoreceptor Development R 2 R 3 R 1 R 8 R 7 R 5 R 4 R 6 R 8 R 7 1 3 5 7 8 Fly Eye Development Sequential formation of Patterning of the eye imaginal disc photoreceptor clusters Furrow dpp A P hh

  6. Formation of the Vertebrate Eye

  7. Comparative Eye Development Fly Vertebrate Squid

  8. Eye Wild-type Wing Wing Mis-expressing Human pax6 gene Is Eyeless/Pax6 a Master Gene for Eye Development? Arguments in Favor: Decreased activity of pax6 genes results in reduced eye size in flies, mice, and humans. 2) pax6 genes are expressed in the early eye primordia of flies, humans, and squid, in which eyes were thought to have evolved independently. 3) Mis-expression of fly or human pax6 genes in certain fly tissues (e.g. wing) result in formation of ectopic eyes.

  9. Jesper Kronhamn, Erich Frei, Michael Daube, Renjie Jiao, Yandong Shi, Markus Noll, and Åsa Rasmuson-Lestander Headless flies produced by mutations in the paralogous Pax6 genes eyeless and twin of eyeless Development 2002 129: 1015-1026. Normal Fly head Fly Lacking eyeless Function Is Eyeless/Pax6 a Master Gene for Eye Development? Arguments Against: Elimination of eyeless or pax6 gene function results in loss of more brain structures than eyes (e.g. completely headless flies). 2) eyeless expression only induces eyes in certain tissues (e.g., wing). 3) Several other genes (sine oculus, eyes absent,daschund) play roles similar to pax6 in eye development. 4) The regulatory relationships between eye determining genes are different in flies versus vertebrates.

  10. Evolutionary Conservation of Hox Expression Patterns

  11. Eyespot? Sensory Appendages? Head Abdomen Tail Anus/ Genitals Mouth Gills? A/P Axis D/V Axis Dpp/BMP4 Non-neural Ectoderm Photosensitive Protrusions or Neural Ectoderm Hox genes Sog/Chd organs appendages Reconstructing the Common Ancestor of Flies and Humans

  12. What Was So Great About Our the Common Ancestor? The Question: The common ancestor of humans and flies must have lived in a complex eco-system with many other species, some of which it ate and others of which it ate. 2) The creature and its decedents somehow displaced all other animal forms. 3) Why?? What was so great about this animal?? Possible Answers: The ancestor evolved a mechanism for extracting low levels of oxygen from the atmosphere and delivering them to internal tissues. 2) The ancestor evolved HOX genes, which allowed for the subsequent diversification of individual body parts.

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