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Early Development: Invertebrates

Early Development: Invertebrates. Brief overview of early developmental themes Early development of Sea Urchin Early development of Caenorhabditis elegans. Invertebrates? So what?. Very easy to study Genetics and molecular events are highly conserved. Cleavage initiation.

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Early Development: Invertebrates

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  1. Early Development: Invertebrates • Brief overview of early developmental themes • Early development of Sea Urchin • Early development of Caenorhabditiselegans

  2. Invertebrates? So what? • Very easy to study • Genetics and molecular events are highly conserved

  3. Cleavage initiation • Maternal Factors • Mitosis Promoting Factor • No Gaps at first • Mid Blastula transition-Gene activation from Zygote nucleus.

  4. Cell and nuclear division • Karyokinesis • Cytokinesis • Centrioles and axis determination.

  5. Patterns of Cell division

  6. Gastrulation

  7. Cell specification and Axis formation • Cell-cell signaling or acquisition of cellular factors • Bound to egg cytoplasm • Actively transported • Associate with centrioles

  8. Sea Urchin: Initial Cleavage

  9. Fate Mapping of Sea Urchin embryo

  10. Global regulatory networks • Maternal Factors • Disheveledand b-catenin • b-catenin and TCF- Micromere differentiation

  11. Double Negative Gate GeneA Gene B Gene C Gene D Gene E Gene F

  12. Double Negative Gate: Micromere Otx/b-catenin Pmar1 HesC Alx1 Thr Ets Delta

  13. Double Negative Gate: Veg2 cell Pmar1 HesC Alx1 Thr Ets Delta

  14. Specification of Vegetal Cells • Wnt signaling; Early Signal (ES); Delta (Notch) • b-cateninBlimp1 wntautocrine; Endoderm differentiation • Pmar1 and HesC regulate ES, which leads to mesoendoderm differentiation. • Delta Mesoderm differentiation.

  15. Axis specification • Animal/Vegetal= Anterior/Posterior axis • Nodal regulates Oral/Aboral axis

  16. Gastrulation • Blastula hatches from Fertilization envelope. • Skeletogenicmesenchyme ingression. • Vegetal plate involutes beginning invagination.

  17. Gastrulation

  18. Gastrulation

  19. Gastrulation

  20. Caenorhabditiselegans

  21. C. elegansand Initial Cleavage

  22. Anterior-Posterior Axis • Sperm Pronucleus location • Cyk-4 activates GTPases relocates PAR proteins to anterior • P-granules: Ribonucleoprotein complex • RNA helicases • Poly A polymerases • Translation initiators

  23. Dorsal-Ventral/Left-Right Axis formation

  24. Specification: Autonomous • Maternal cytoplasmic factors • SKN-1: EMS fate determination. • PAL-1: Differentiation of P2 somatic descendents • PIE-1: placed into P blastomeres via PAR-1, inhibits SKN-1 and PAL-1 in P cells.

  25. Specification: Conditional • Cell-cell signaling (Juxtacrine) • Paracrine signaling

  26. Gastrulation

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