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miRNA

miRNA. miRNA ancient form of regulation. Protection against viral pathogens Quick regulation and turnover of mRNA. Drosophila Development: Genetics at work!. Development of Drosophila. Closer look at Early Development of Drosophila. Cellularization. Gastrulation and Segmentation.

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miRNA

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  1. miRNA • miRNA ancient form of regulation. • Protection against viral pathogens • Quick regulation and turnover of mRNA.

  2. Drosophila Development: Genetics at work!

  3. Development of Drosophila

  4. Closer look at Early Development of Drosophila.

  5. Cellularization

  6. Gastrulation and Segmentation

  7. Anterior-Posterior Polarity in Oocyte • Starts during oogenesis • Gurken mRNA transferred to oocyte. • Signal sent back to oocyte post Gurken/Torpedo interaction. • Par-1 mediated organization of microtubules to posterior side of oocyte via Oskar. Minus end (posterior) and plus end (anterior).

  8. Dorsal-Ventral Patterning in Oocyte.

  9. Dorsal Gradient

  10. Anterior-Posterior Polarity in Embryo

  11. Syncytial Specification in Drosophila

  12. Anterior-Posterior Polarity in Embryo

  13. Translational Regulation • Stored oocyte mRNAs- selective inhibition of translation. • Genes turned on quickly post-fertilization. • Relies on the recruitment of proteins involved in making a polyA tail. • Drosophila Bicoid gene product.

  14. Gap Genes • Role in early segmentation • Transcriptional regulators

  15. Pair-rule Genes • Another set of Transcriptional Regulators. • Develops the precursors for the actual segments. • Zebra-stripe pattern of expression. • Stripe position determined by which enhancer is bound.

  16. Pair-rule Genes

  17. Segment Polarity Genes • Wingless (Wnt) and Hedgehog signal pathway proteins. • Paracrine signaling maintains segmentation.

  18. Homeotic Selector Genes (Hox) • Regulated by Pair-rule and Gap genes. • Antennapedia Complex and bithorax complex. • AbdA and AbdB repressed by Hunchback and Kruppel. • Repression maintained by Polycomb, activation maintained by Trithorax.

  19. Epigenetic Memory • Trithorax- keeps genes active. • Counteract Polycombs • Modify nucleosomes • Keep H3K4 trimethylated • Polycomb- keeps genes inactivated. • H3K27 methylase • Bind meH3 tails

  20. Hox Genes in Other Species • Mouse Limb development-deletion of Hoxd11, Hoxd12, Hoxd13 causes polydactyly • Zebra fish, loss of H3K27 demethylase activity and subsequent Hox gene disregulation- poor tail development

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