1 / 32

Early Vertebrate Development

Early Vertebrate Development. Axis Determination Amphibian Early Development: Frog Fish Early Development: Zebra Fish. Heads or Tails? Axis specification . Common theme in early development Conserved mechanisms Divergent mechanisms. Early Vertebrate Development: Xenopus.

minh
Download Presentation

Early Vertebrate Development

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Early Vertebrate Development • Axis Determination • Amphibian Early Development: Frog • Fish Early Development: Zebra Fish

  2. Heads or Tails? Axis specification • Common theme in early development • Conserved mechanisms • Divergent mechanisms

  3. Early Vertebrate Development: Xenopus

  4. Xenopus: Cleavage • Sperm entry point: Dorsal-Ventral (D-V) axis • Microtubule array • Cortical rotation.

  5. Xenopus: Cleavage • Radially Symmetrical; Holoblastic • High amount of yolk in vegetal half. • Second cleavage before first finishes. • Third= equatorial • 16-64 cell stage: Morula • 128 cell stage: Blastula

  6. Mid-Blastula Transition • DNA demethylation • H3K4 methylated (trimethylation) transcription activation • Ex. Vegetal cells  endoderm. Produce paracrine factors that induce mesoderm specification of cells above.

  7. Xenopus: Gastrulation • Same goals as other organsims: get cells to appropriate locations! • Movements start in Gray Crescent, cells invaginate to form slit-like blastopore.

  8. XenopusGastrulation: Involution Vegetal Rotation: Movement of Pharyngeal endoderm above involuting mesoderm. InvolutingMarginal Zone (IMZ)

  9. Xenopus: Gastrulation

  10. XenopusGastrulation: Convergent extension

  11. Axis specification in Xenopus: Induction • Animal-Vegetal axis determines tissue type • A-V, D-V, and L-R axis specification is triggered by fertilization • Primary embryonic induction. • Hans Spemann and Hilde Mangold- The Organizer

  12. Axis Specification in Xenopus: Molecular Mechanism • Dorsal Signal: b-catenin, Nodal, and Vg1. • Bone Morphogenic Proteins (BMPs) • noggin • chordin • follistatin

  13. Regional Neural Induction in Xenopus • Head inducer: Wnt inhibitors • Cerberus • Frzb, Dickkopf • Insulin-like Growth factors • Trunk patterning: • Wnt and Retinoic Acid

  14. Frogs are left handed! • XenopusNodal related protein (Xnr-1) determines left-right axis • Xnr-1 is expressed on Left side. • Pitx2 is activated by Xnr-1 and also persists on left side. Injection of Pitx2 on right side alters gut coiling and heart placement.

  15. Early Vertebrate Development: Daniorerio

  16. DanioGastrulation

  17. Epiboly and beginning formation of notocord

  18. Axis Formation: Danio • D-V axis: BMP/Wnt inhibitors regulated by b-catenin and Nodal-like proteins. • Fish Nieuwkoop center = Organizer.

  19. DanioA-V axis formation

  20. Left-Right Axis formation in Danio

  21. Early Vertebrate Developement

  22. Early Vertebrate Developement

  23. Early Vertebrate Developement

  24. Early Vertebrate Developement

  25. Early Vertebrate Developement

  26. Early Vertebrate Developement

  27. Early Vertebrate Developement

  28. Early Vertebrate Developement

  29. Early Vertebrate Developement

  30. Early Vertebrate Developement

  31. Early Vertebrate Developement

  32. Early Vertebrate Developement

More Related