lecture 1 course outline central problem in development terms cellular mechanisms of determination
TRANSCRIPT
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.
• Labs: Illustration of some basic techniques used in Developmental genetics. Lab report written in the format of a scientific paper.
Jan 12 Lecture 1 Introduction to developmental geneticsJan 19 Lecture 2 Introduction to genetic dissection: screens, complementation and epistasis.Jan 26 Lecture 3 Drosophila cell biologyFeb 2 Lecture 4 Modern Drosophila genetics Feb 9 Lecture 5 Anterior posterior axis formationFeb 16 Lecture 6 Anterior posterior axis formation continuedFeb 23 SLACK WEEK March 1 Lecture 7 MorphogensMarch 8 Lecture 8 Nuclear gradients and the habits of developmental signaling pathwaysMarch 15 Lecture 9 Short course on C. elegans cell biology and genetic analysis.March 22 Lecture 10 Lateral inhibition—emergent properties in developmentMarch 29 Lecture 11 Short course on Evolution and Development.April 5 Lecture 12 Experimental approaches to Evo Devo. Paper due.
Schedule of Lectures
Date for the Midterm examination
Monday February 27, 2012 This is the Monday right after slack week 7-10PM.
This midterm will cover materialup to Lecture 6 Anterior Posterior axis.
The course web site can be foundat instruct.uwo.ca/biology/4540g
This web site contains all the information you need for thiscourse. Consult it. Explore it.
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
Schedule of the Labs and in class tests
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
Long labs
The lab test on the readings
Why am I doing this to you? In the pastI expected students to read the paperson their own before coming to the lab.Over the years it become clear that thiswas not occurring. Reading in the firsthalf of the term saves a lot of pain later.Since I know this, I am being a pain now.
Format of the test on the readings
You will have 5 minutes to answerone question at the beginning of the lab.
The question asked will be differenton Monday and Tuesday.
This and the next lecture will focuson definition of the terms and basicgenetic concepts used in Developmentalgenetics.
The central problem in Development
“How is the information stored in linear DNAtransformed over time into a three dimensionalmulticellular organism?”
From this perspective the problem seemslimitless.
However, the size of the genome providesa limit on the problem because all informationrequired for hand development is somehowencoded in the genome.
What is animal development?
What is animal development?
• It is an essential part of our and all animal life cycles.
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.
General animal life cycle
Soma
Germ-line
fertilization fertilization
General animal life cycle
Soma
Germ-line
fertilization fertilization
Somatic germ-linedivision
General animal life cycle
Soma
Germ-line
fertilization fertilization
Somatic germ-linedivision
Life does not begin at fertilization; it is a continuousprocess.
What are the characteristics of animal development?
Development at its most basic level.
Single celledZygote
Decisions
Complex multicellular organismof many specialized cell typesand organs.
Two terms used in Developmental Biology.
Determination
Differentiation
More terms
Cell specification
versus
Pattern formation
Examples of cell specification
Lens: each cell as it differentiates becomestransparent.
Red blood cell: no nucleuspacked with hemoglobin.
Example of pattern formation
You distinguish an arm froma leg by its shape and not bywhat it is made up of whichis basically the same stuff:bone, muscle, nerves etc..
This is an abstract ability, because shape is a quality defined only by what it is.
Cellular mechanisms of determination
• Intrinsic
• Extrinsic
mRNA
protein
Anterior Posterior
Example of an intrinsic mechanism:Assymetric determinant
Bicoid mRNA and protein areassymetrically localized in the cell.
Extrinsic mechanisms
• A) Lateral inhibition
• B) Induction
Lateral inhibition during neurogenesis in Drosophila.
Example of an emergent property because before the processstarts you can not tell which cell will be neurogenic and whichwill be epithelial.
Delta ligand
Notch receptor
Start off with identical levels of expression intwo cells.
Delta ligand
Notch receptor
Start off with identical levels of expression intwo cells.
No Net signal
Due to a stochastic (random, chance) event one cell expressesmore Delta ligand than the other.
The net signal is in this direction.The activation of Notch receptor results indecreased Delta expression.
Dl
When Notch or Delta are absent, the ectoderm cellsbecome neurogenic. The cell that becomes the neuroblastinhibits the surrounding cells from this fate, and telling themto become epithelial cells instead. Lateral inhibition.
Neuroblast Epithelial
Notch
Neuroblast
Epithelial
Induction
1
2
A cell or group of cells removedfrom a second cell
that directs the developmentalfate of a second cell or group ofcells.
Example of induction
Anchor cell-gonad
signals
Epidermis
Vulva
What molecules control determination?
Gut
Brain
Analysis of gene regulation: cis regulation.
gene something
embryo of something
ORF
ATG
Translational fusion to a reporter gene
Reporter gene
ATGGFP
TATA
Regulatory regions of the gene
ATGGFP
TATA
Regulatory regions of the gene
Gut
Brain
ATGGFP
TATA
Regulatory regions of the gene
Gut
Brain
Gut
Brain
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
Mutagenesis
Gut
Brain
Gut
Brain
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
Mutagenesis
Gut
Brain
Gut
Brain
Gut
Brain
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
Mutagenesis
Gut
Brain
Gut
Brain
Gut
Brain
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
Mutagenesis
Gut
Brain
Gut
Brain
Gut
Brain
Gut
Brain
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
Mutagenesis
Gut
Brain
Gut
Brain
Gut
Brain
Gut
Brain
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
Mutagenesis
Gut
Brain
Gut
Brain
Gut
Brain
Gut
Brain
Gut
Brain
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
Mutagenesis
Gut
Brain
Gut
Brain
Gut
Brain
Gut
Brain
Gut
Brain
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
ATG GFP
TATA
Mutagenesis
Gut
Brain
Gut
Brain
Gut
Brain
Gut
Brain
Gut
Brain
Gut enhancer
Brain enhancer
Gut silencer
ATG
Heterologous TATA box
Transcriptional fusion
Gut
Brain
Gut enhancer
Brain enhancer
Gut silencer GFP
ATG GFP
Gut
Brain
ATG GFP
Gut
Brain
ATG
ATG
Gut enhancer
Brain enhancer
Gut
Brain
Gut
Brain
ATG GFP
Gut
Brain
ATG
ATG
Gut enhancer
Brain enhancer
Gut
Brain
Gut
Brain
ATG GFP
Gut
Brain
ATG
ATG
Gut enhancer
Brain enhancer
Gut
Brain
Gut
Brain
ATGGut enhancer
Gut silencer Gut
Brain
ATG GFP
Gut
Brain
ATG
ATG
Gut enhancer
Brain enhancer
Gut
Brain
Gut
Brain
ATGGut enhancer
Gut silencer Gut
Brain
Important property:
Necessary and Sufficient
Developmental pathways
Transcription factor signal transcription factor pathways
TF A SF Signaltransduce
TF B
Ci Wingless FrizzledDshArm
LefEn
En Hedgehog PatchedSmooth
Ci