Gene regulation in Drosophila melanogaster Genetic studies

1. Gene regulation in Drosophila melanogaster Genetic studies One of the best understood developmental systems 13,600 genes Axis determination Signaling pathway Transcriptional and translational regulation The genetics of axis specification in Drosophila The Chapter 9 of Developmental Biology by Scott Gilbert, 7th edition Chang-Gung University Dr. Li-Mei Pai

2. Targeted ectopic expression of the Eyeless gene--induce eyes to develop in locations such as legs and antennae Closely related genes initiate the development program for the same organ in animals separate by 500 million years of evolution

3. Life cycle of Drosophila 4 stages: embryo, larva, pupa, adult Culture condition: 250C and 60% humidity

4. Science, 297, 2270-2275, 2002

5. Comparison of Larval and Adult Segmentation in Drosophila Body patterning of fly One cell to an organism

6. Laser Confocal Micrographs of Stained Chromatin Showing Superficial Cleavage in a Drosophila Embryo

7. Early development of Drosophila Rapid division 8 mins/division 9 divisions asynchronous 13 divisions Single cell

8. Formation of the Cellular Blastoderm in Drosophila

9. Transgenic flies

10. Gastrulation One single epithelial layer –all tissues Mesoderm—muscle, connective tissues Endoderm---midgut (foregut and hidgut- Ectoderm) Ectoderm---nervous tissue and epidermis

11. Figure 9.5(1) Gastrulation in Drosophila

12. Figure 9.5(2) Gastrulation in Drosophila Germ band extention

13. Figure 9.5(3) Gastrulation in Drosophila Germ band retraction

14. The sequential expression of different sets of genes establishes the body plan along the anterior-posterior axis The sequential expression of different sets of genes establishes the body plan along the anterior-posterior axis The sequential expression of different sets of genes establishes the body plan along the anterior-posterior axis Localized mRNA and Proteins Translated after fertilization— Positional information to activate zygotic genes Temporal sequence parasegment Pattern in the segment Segment identities

15. Maternal effect genes—( do not damage mother) preformed mRNA and proteins in the egg Zygotic genes—embryo nuclei

16. Three classes of mutants affect the anterior, posterior, and terminal development head and thoracic abdominal acron and telson

17. Polarization of the body axes during oogenesis Polarization of the body axes during oogenesis Polarization of the body axes during oogenesis each egg chamber: 3 types of cells Oocyte with nucleus (germinal vesicle-GV) Connected to 15 nurse cells }---germ-line Surrounded by a monolayer of about 1000 somatic folliclecells

18. Three independent Genetic Pathways Interact to Form theAnterior-Posterior Axis of the Drosophila Embryo

19. Three independent Genetic Pathways Interact to Form the Anterior-Posterior Axis of the Drosophila Embryo

20. Specifying the Anterior-Posterior Axis of the Drosophila Embryo During Oogenesis

21. Specifying the Anterior-Posterior Axis of the Drosophila Embryo During Oogenesis Protein kinase A orients the microtubules

22. Gradient of Bicoid Protein in the Early Drosophila Embryo bicoid mRNA in the anterior tip of the embryo 3’ untranslated region Exuperantia and Swallow proteins link bicoid to dynein ATPases Fertilization-receives a longer polyadenylate tail-trnaslated

23. Gradient of Bicoid Protein in the Early Drosophila Embryo concentrated in the nuclei

24. Experiments Demonstrating that the bicoid Gene Encodes the Morphogen Responsible for Head Structures in Drosophila

25. Gradient of Caudal Protein in the Syncitial Blastoderm of aWild-type Drosophila Embryo Activates genes responsible for the invagination of the midgut Bicoid binds to its 3’UTR and prevents its translation

26. Anterior-Posterior Pattern Generation by the DrosophilaMaternal Effect Genes

27. Control of hunchback mRNA Translation by Nanos Protein

28. Anterior-Posterior Pattern Generation by the DrosophilaMaternal Effect Genes Bicoid stimulates hunchback transcription All transcription factors

29. zygotic maternal

30. Formation of the Unsegmented Extremities by torso Signaling torso-receptor tyrosine kinase Distinction A/P is bicoid Groucho –transcriptional inhibitor tailless, huckebein

31. Model of Drosophila Anterior-Posterior Pattern Formation Maternal effect genes Zygotic genes Syncytial blastoderm Cellular blastoderm

32. Conversion of Maternal Protein Gradients into Zygotic Gap Gene Expression Transcription factor

33. Conversion of Maternal Protein Gradients into Zygotic Gap Gene Expression

34. Model of Drosophila Anterior-Posterior Pattern Formation Maternal effect genes Zygotic genes Syncytial blastoderm Cellular blastoderm

35. Specific Promoter Regions of the even-skipped (eve) Gene Control Specific Transcription Bands in the Embryo Division cycle 13

36. the 2nd parasegmentthe expression of eve Hypothesis for the formation of the Second Stripe of Transcription from the even-skipped Gene Bicoid and hb activate eve Kruppel and giant repress eve

37. Hypothesis for the Formation of the Second Stripe of Transcriptionfrom the even-skipped Gene 5 sites 3 sites 6 sites 3 sites Cis-regulatory enhancer elements Trans-regulatory gap gene proteins

38. Model for the Transcription of the Segment Polarity Genesengrailed and wingless (wg) Reinforce the PS Cell-cell signaling

39. Model for the Transcription of the Segment Polarity Genesengrailed and wingless (wg)

40. Model for the Transcription of the Segment Polarity Genesengrailed and wingless (wg) gradients

41. Homeotic Gene Expression in Drosophila Homeotic complex head abdomen thoracic 3rd thoracic

42. A Four-winged Fruit Fly Constructed by Putting Together Three Mutations in cis Regulators of the Ultrabithorax Gene Homeotic mutants Ultrabithorax gene is deleted T3 to T2 transformation

43. Effect of Mutations Affecting the Distribution of the Dorsal Protein

44. Translocation of Dorsal Protein into Ventral, but not Lateral or Dorsal, Nuclei

45. The Generation of Dorsal-Ventral Polarity in Drosophila

46. Conserved Pathway for Regulating Nuclear Transport of TranscriptionFactors in Drosophila and Mammals

47. Model for the subdivision of the dorso-ventral axis into different regions by the gradient in nuclear dorsal protein Zygotic genes pattern the early embryo Dorsal protein activates twist and snail represses dpp,zen, tolloid Rhomboid----neuroectoderm Repressed by snail (not most ventral) Binding sites for dorsal protein in their regulatory regions

48. Patterns of Gene Expression During Drosophila Mesoderm Development Eileen E. M. Furlong, Erik C. Andersen, Brian Null, Kevin P. White, Matthew P. Scott Science, 293, 1629, 2001 Goals of Experiments Suggestions, opinions

49. Subdivision of the Dorsal-Ventral Axis by the Gradient ofDorsal Protein in the Nuclei

50. TABLE 1. Cancer-related genes in Drosophila melanogaster Fly genes homologous to mammalian oncogenes Mammalian gene or product b-catenin c-abl Akt aurora 1, aurora 2, AIM-1 Meis1 c-cbl c-crk Gli1, Gli2, Gli3 cyclin D/ PRAD1 Ras ret Smo c-src cdc25 All1 TCF c-erbB-2 Fly genes armadillo D. Abl D. Akt aurora homothorax Dcbl Dcrk ci cyclin D Ras D.ret smoothened smo Src42A, Src64B string trithorax ALL-1 D.TCF torpedo