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Lecture 1

Lecture 1. Course Outline Central problem in Development Terms Cellular mechanisms of determination. Objectives. Lectures: application of genetic analysis to problems in development. Emphasis on problem solving as opposed to rote memorization.

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Lecture 1

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  1. Lecture 1 Course Outline Central problem in Development Terms Cellular mechanisms of determination

  2. Objectives • Lectures: application of genetic analysis to problems in development. Emphasis on problem solving as opposed to rote memorization. • Labs: Illustration of some basic techniques used in Developmental genetics. Lab report written in the format of a scientific paper.

  3. Schedule of Lectures Jan 12 Lecture 1 Introduction to developmental genetics Jan 19 Lecture 2 Introduction to genetic dissection: screens, complementation and epistasis. Jan 26 Lecture 3 Drosophila cell biology Feb 2 Lecture 4 Modern Drosophila genetics Feb 9 Lecture 5 Anterior posterior axis formation Feb 16 Lecture 6 Anterior posterior axis formation continued Feb 23 SLACK WEEK March 1 Lecture 7 Morphogens March 8 Lecture 8 Nuclear gradients and the habits of developmental signaling pathways March 15 Lecture 9 Short course on C. elegans cell biology and genetic analysis. March 22 Lecture 10 Lateral inhibition—emergent properties in development March 29 Lecture 11 Short course on Evolution and Development. April 5 Lecture 12 Experimental approaches to Evo Devo. Paper due.

  4. Date for the Midterm examination Monday February 27, 2012 This is the Monday right after slack week 7-10PM. This midterm will cover material up to Lecture 6 Anterior Posterior axis.

  5. The course web site can be found at instruct.uwo.ca/biology/4540g This web site contains all the information you need for this course. Consult it. Explore it.

  6. Schedule of the Labs and in class tests Jan 9/10 NO LAB Jan 16/17 Lab 1 Preparation of first instar larval cuticles (test) Jan 23/24 Lab 2 Ectopic expression of Fushi tarazu (come in the day before). Fixation of embryos for Labs 3&4 (test) Jan 30/31 Lab 3 Engrailed antibody staining (long lab) (test) Feb 6/7 Lab 4 Wingless in situ hybridization (come in the day before; long lab) (test) Feb 13/14 Lab 5 Beta-galactosidase staining for assaying ftz enhancer activity. (test) NO MORE LABS

  7. Long labs Jan 9/10 NO LAB Jan 16/17 Lab 1 Preparation of first instar larval cuticles Jan 23/24 Lab 2 Ectopic expression of Fushi tarazu (come in the day before). Fixation of embryos for Labs 3&4 Jan 30/31 Lab 3 Engrailed antibody staining (long lab) Feb 6/7 Lab 4 Wingless in situ hybridization (come in the day before; long lab) Feb 13/14 Lab 5 Beta-galactosidase staining for assaying ftz enhancer activity. NO MORE LABS

  8. The lab test on the readings Why am I doing this to you? In the past I expected students to read the papers on their own before coming to the lab. Over the years it become clear that this was not occurring. Reading in the first half of the term saves a lot of pain later. Since I know this, I am being a pain now.

  9. Format of the test on the readings You will have 5 minutes to answer one question at the beginning of the lab. The question asked will be different on Monday and Tuesday.

  10. This and the next lecture will focus on definition of the terms and basic genetic concepts used in Developmental genetics.

  11. The central problem in Development “How is the information stored in linear DNA transformed over time into a three dimensional multicellular organism?”

  12. From this perspective the problem seems limitless. However, the size of the genome provides a limit on the problem because all information required for hand development is somehow encoded in the genome.

  13. What is animal development?

  14. What is animal development? • It is an essential part of our and all animal life cycles.

  15. What is animal development? • It is an essential part of our and all animal life cycles. • At the present time only life can beget life.

  16. General animal life cycle Soma Germ-line fertilization fertilization

  17. General animal life cycle Soma Somatic germ-line division Germ-line fertilization fertilization

  18. General animal life cycle Soma Somatic germ-line division Germ-line fertilization fertilization Life does not begin at fertilization; it is a continuous process.

  19. What are the characteristics of animal development?

  20. Development at its most basic level. Single celled Zygote Decisions Complex multicellular organism of many specialized cell types and organs.

  21. Two terms used in Developmental Biology. Determination Differentiation

  22. More terms Cell specification versus Pattern formation

  23. Examples of cell specification Lens: each cell as it differentiates becomes transparent. Red blood cell: no nucleus packed with hemoglobin.

  24. Example of pattern formation You distinguish an arm from a leg by its shape and not by what it is made up of which is basically the same stuff: bone, muscle, nerves etc.. This is an abstract ability, because shape is a quality defined only by what it is.

  25. Cellular mechanisms of determination • Intrinsic • Extrinsic

  26. Example of an intrinsic mechanism: Assymetric determinant Bicoid mRNA and protein are assymetrically localized in the cell. mRNA protein Posterior Anterior

  27. Extrinsic mechanisms • A) Lateral inhibition • B) Induction

  28. Lateral inhibition during neurogenesis in Drosophila. Example of an emergent property because before the process starts you can not tell which cell will be neurogenic and which will be epithelial.

  29. Delta ligand Notch receptor Start off with identical levels of expression in two cells.

  30. Delta ligand Notch receptor No Net signal Start off with identical levels of expression in two cells.

  31. Due to a stochastic (random, chance) event one cell expresses more Delta ligand than the other. Dl The net signal is in this direction. The activation of Notch receptor results in decreased Delta expression.

  32. Neuroblast Epithelial Epithelial Notch Neuroblast When Notch or Delta are absent, the ectoderm cells become neurogenic. The cell that becomes the neuroblast inhibits the surrounding cells from this fate, and telling them to become epithelial cells instead. Lateral inhibition.

  33. Induction A cell or group of cells removed from a second cell 1 2 that directs the developmental fate of a second cell or group of cells.

  34. Example of induction Anchor cell-gonad signals Epidermis Vulva

  35. What molecules control determination?

  36. Analysis of gene regulation: cis regulation. ORF gene something Brain Gut embryo of something

  37. Translational fusion to a reporter gene ATG Reporter gene

  38. Regulatory regions of the gene GFP ATG TATA

  39. Regulatory regions of the gene GFP ATG TATA Brain Gut

  40. Regulatory regions of the gene GFP ATG TATA Brain Brain Gut Gut

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