9. I can’t wait to grow up!

12. Laugh now

13. The fruit fly body plan is self-assembled in 24 hours

14. How is the body plan specified? Egg ---> animal in 24 hours!

15. Eric Wieschaus and Christiane Nüsslein-Volhard used genetics to identify proteins that set up the embryonic body plan

16. The molecular genetics of pattern formation in candy corn The wild-type pattern Anterior Posterior

17. We collected a series of mutants affecting the body plan Wild-type Anterior group Gap gene Posterior group Morphogenesis defects

18. The wild-type body is segmented and each segment has a unique identity and thus produces distinctive structures

19. Wieschaus and Nüsslein-Volhard removed single genes and looked for effects on the body plan

20. Wildtype larva bicoid mutant bicoid mutants have no head!! Gilbert Fig. 9.13

21. Remember that cleavage starts without cell division in Drosophila

23. = bicoid mRNA= nanos mRNA

25. Increasing Bicoid concentration Head Tail Bicoid accumulates in a gradient

26. A gradient of the bicoid transcription factor turns on different genes at different "thresholds"

27. These “bicoid target genes” are known as the gap genes Hunchback Kruppel Knirps Expression pattern of proteins ecoded by gap genes

28. Hunchback Kruppel

29. Gap gene mutants are missing different regions of the body

30. Wildtype Krüppelhunchback knirps

32. Hunchback Kruppel

33. Alberts Chapter 8 title page

34. So, in summary so far… Maternal Determinants Zygotic Gap Genes Zygotic Pair-rule Genes

35. Figure 9.8(1) Model of Drosophila Anterior-Posterior Pattern Formation

36. Isn’t life wonderful, beautiful and incredible!

39. Ed Lewis was far ahead of his time

40. who’s

41. Wildtype Antennapedia mutant

45. Wildtype Ubx mutant T2 A2 T3 and A1 take on a 2nd thoracic identity T2

46. Wildtype Ubx abdA AbdB triple mutant T2 T3 A1 A8 T2 All segments take on a 2nd thoracic identity

47. Is Ubx is expressed at the right time and place to make in T3 different from T2? Yes! Ubx is expressed in T3 and A1

50. Figure 9.28 Homeotic Gene Expression in Drosophila

52. Ultrabithorax, abdA, and AbdB normally repress expression of the“leg gene” Distalless in the abdominal segments Distalless in wild-typeDistalless in triple mutant T1 T2 T3 abdomen

53. Lewis hypothesized that the duplication and diversification of homeotic master regulators underlies the evolution of an increasingly complex body plan

54. The human body is also built up from reiterated units with different identities along the A/P axis

56. As we’ll see later, mammals also have homeotic genes expressed at different places along the A/P axis

61. DELTA mutant cells can be rescued by wild type neighbors. Therefore, DELTA must be the SIGNAL. NOTCH mutant cells cannot be rescued by wild type neighbors. Therefore, NOTCH must be the Receptor.