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Drosophila melanogaster

Drosophila melanogaster. 2.5mm. Movie. The Life Cycle. 12 hr. 1-2 weeks. 36hr. 60 hr. 2 2 3 3 4 4. The Fly Genome. 3 autosomal pairs (2,3,4) Sex chromosomes XX, XY. 165Mb 14,000 genes 50% have a human homolog 61% of human disease genes have a fly counterpart.

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Drosophila melanogaster

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  1. Drosophila melanogaster 2.5mm Movie

  2. The Life Cycle 12 hr 1-2 weeks 36hr 60 hr

  3. 2 2 3 3 4 4 The Fly Genome 3 autosomal pairs (2,3,4) Sex chromosomes XX, XY 165Mb14,000 genes 50% have a human homolog 61% of human disease genes have a fly counterpart Developmentally-Regulated Gene Expression Adult cDNALarval cDNA

  4. Developmentally-Regulated Gene Expression

  5. Oogenesis Filaments 0.5mm

  6. Nurse cells Oocyte Maternal Effect Genes Oscar mRNA Gurken (TGF-alpha) mRNA

  7. Anterior-Posterior Gradients

  8. Early Development Disconnects Mitosis from Cytokinesis Movie GFP-tau marks microtubules 90 mins post-fertilization

  9. Pole Cells Inherit Polar Ganules Containing Oscar Posterior end Anterior end 120 minutes post-fertilization

  10. Cellularization Traps Nuclei in Different Microenvironments D V A P Immunolocalization of Bicoid, Even-skipped andCaudal Proteins

  11. Cascades of Gene Activity Set up the Drosophila Body Plan Maternal Coordinate Genes Bicoid, Nanos, Caudal Anterior-Posterior, Dorsal-Ventral Axes Gap Genes Hunchback, Kruppel, Knirps Anterior/Middle/Posterior Pair Rule Genes (7 stripes) Even-skipped, Hairy, Fushi Tarazu Segmentation Segment Polarity Genes Wingless, Hedgehog, Engrailed Define the A-P axis of 14 segments Homeotic Genes Define the identity of the segments

  12. Events of Embryogenesis Stage Timing Landmark event

  13. Morphogenesis Movie

  14. Gastrulation Establishing the Mesoderm Animation Blastocoel "The most important event in your life is not birth, marriage, or death, but gastrulation.” - L. Wolpert Followed by germ cell placement and introgression of the endoderm Twist is a bHLH transcription factor that will later turn on fibroblast growth factor (FGF) receptors 3 hours post-fertilization

  15. The (Segmented) Larva 3+3+8=14 Head Tail

  16. Metamorphosis 24 hours post-fertilization

  17. Wild-type ultrabithorax mutant Homeotic Mutations converts halteres to wings Convert One Segmental Identity into Another Wild-type Antennapedia

  18. Homeotic Genes Drosophila Mouse Drosophila Xenopus C. elegans Conserved homeobox DNA binding domain

  19. A Few Questions for Thought • How might enhancer elements (studied in the Arabidopsis lab) “simplify” issues of gene expression multicellular organisms? How might they promote evolutionary change? • In a proverbial case of the chicken or the egg, how does Drosophila pattern its the embryo? • Describe the specific contributions of Bicoid, Caudal, Hunchback and Nanos to early embryonic development Extend your description to include how a segmented animal is formed and how those segments are determined to specific identities by cascades of gene expression. • Review the landmark events of morphogenesis as the hollow ball of cells called the blastoderm is converted into a larva. • Explain how the larva in turn is converted into an adult fly in metamorphosis. What are the roles of homeotic genes in this process?

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