1. Drosophila – 2 lectures (½ – 1- ½ ) Cleavage View -gastrulation, organogen. frame metamorph. Once we know the embryo, meet the molecules Because this is a largely ‘solved’ system Because these genes have key roles in all metazoans EVERY one of 5000 cleavage state cell has a D/V and A/P ‘molecular address’, and is therefore specified.

2. Both axes defined in Drosophila First to Anterior- Posterior Axis (A-P)

12. Bicoid mRNA 1. Bicoid RNA ‘caught’ at the ‘entrance’ 2. Unanchored Bicoid RNA returned to the anterior side by dynein on MTs

13. Show: Bcd-gastrulation Gastrulation-dorsal

15. In syncitium For control of Hunchback protein – Bicoid is a transcription factor, but Nanos...

16. Nanos is an RNA binding protein that PREVENTS Hunchback Translation

17. Gap genes are turned on in broad stripes by maternal genes, each other. ALL TFs. Hunchback Gt Kr kn hb (later)

18. Gt Kr kn hb (later)

19. Gap genes are turned on in broad stripes by maternal genes, each other Pair rule genes are turned on in 7 stripes each, harder to conceptualize

20. Each stripe of the P-R gene has its Own enhancer. Even-skipped gene – 7 stripes.

21. Each stripe has its own enhancer, responding to a different combinatorial of Gap and Maternal proteins

23. Gap genes are turned on in broad stripes by maternal genes, each other Pair rule genes are all Trascription Factors too – turn on Segment Polarity gene expression

27. hh hh Two morphogens/ligands/organizers in adjacent cells

32. No Active

33. The embryo Now has two Adjacent organizers Which release a Morphogen From syncitium with Gradient of 1 (or 2) Morphogens, to series Of segments, each With 2 morphogens

36. Both axes defined in Drosophila, every cell of 5000. Now to D/V

40. Figure 23.14 Homologous Pathways Specifying Neural Ectoderm in Protostomes (Drosophila) and Deuterostomes (Xenopus) D/V

42. Gastrulation - Drosophila http://www.flybase.org/data/images/Animation/ AND Course Site (Movies)

44. I.RTK pathwaySets follicle cell D/V state II.Proteolytic cascadeSets embryos’ cell D/V state III.Toll/Cactus/DoralSets nuclear D/V state IV.Dorsal TF thresholdsDiff. pathway per D/V address 4 STAGES OF ESTABLISHING DORSAL/VENTRAL – 4 SEQUENTIAL PATHWAYS + STAGEPATHWAYPATHWAY OUTCOME

45. I.RTK pathwaySets follicle cell D/V state II.Proteolytic cascadeSets embryos’ cell D/V state III.Toll/Cactus/DoralSets nuclear D/V state IV.Dorsal TF thresholdsDiff. pathway per D/V address 4 STAGES OF ESTABLISHING DORSAL/VENTRAL – 4 SEQUENTIAL PATHWAYS + STAGEPATHWAYPATHWAY OUTCOME

46. Dorsal fate determined in oocyte, through signaling between oocyte and somatic follicle cells

47. Gurken protein on future dorsal side of oocyte, facing cells which become dorsal

49. Human blood clotting cascade – Also a series of (extracellular) proteolytic cleavages

52. Dorsalized Ventralized Ventral fates dictated by NUCLEAR presence of the protein Dorsal

53. Gradient of Nuclear Dorsal protein imparts D-V IDs to cells

54. Twist Protein specifies mesoderm

55. Lateral inhibition in neurectoderm to specify neruogenesis: Notch mediated All Rhomboid expressing cells express Notch, then undergo a stochastic process for ¼ cells to become neuronal

56. Lateral inhibition in neurectoderm to specify neruogenesis: Notch mediated

58. Key factor for Dorsal identities in Drosophila Key factor for D-V identities in Vertebrates TGF-Beta family

60. Figure 23.14 Homologous Pathways Specifying Neural Ectoderm in Protostomes (Drosophila) and Deuterostomes (Xenopus) D/V

65. All animals have related developmental histories

69. out in evert

73. Figure 6.16 Scanning Electron Micrograph of a Compound Eye in Drosophila Eye disc patterning controlled by ‘reuse’ of the pathways seen in general axis specification

74. Figure 6.17 Differentiation of Photoreceptors in the Drosophila Compound Eye

75. Figure 6.18 Major Genes Known to be Involved in the Induction of Drosophila Photoreceptors