Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.
-
Upload
daniel-veley -
Category
Documents
-
view
216 -
download
0
Transcript of Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.
![Page 1: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/1.jpg)
Lecture 5
• Anterior Posterior axis formation: Cell Biology
• Bicoid is a morphogen
![Page 2: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/2.jpg)
Lab 5 schedule
• On Monday and Tuesday come in at the regular time.
• On Tuesday and Wednesday come to B&G 3015 to mount your embryos. Elyse will discuss the time of day to come.
![Page 3: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/3.jpg)
Exams
• Midterm Tuesday Feb. 28, 2012
UCC 63, 7-10PM
• Tentative Final exam date Thursday April 19, 2012 at 9:00AM
![Page 4: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/4.jpg)
Structure of the egg
Dorsal appendage
Chorion
VitellineMicropyle
D
V
A P
![Page 5: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/5.jpg)
Cellular Blastoderm
Hartenstein 1993
![Page 6: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/6.jpg)
Blastoderm fate map
Hartenstein 1993
![Page 7: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/7.jpg)
Simplified Fate Map
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 8: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/8.jpg)
Remove posterior pole plasm
Classical Embryology
Remove 5-10% of the anterior cytoplasm
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 9: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/9.jpg)
Transplant anterior cytoplasm to posterior
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 10: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/10.jpg)
Transplant posterior cytoplasm to anterior
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 11: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/11.jpg)
Transplant posterior cytoplasm to anterior
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 12: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/12.jpg)
Transplant posterior cytoplasm to an anterior that lacks the anterior signal
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 13: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/13.jpg)
Properties of the polar center signals
• Both exert long range effects
• The anterior and posterior activities inhibit each other
• Both activities have inductive properties
![Page 14: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/14.jpg)
Properties of the polar center signals
• Both exert long range effects
![Page 15: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/15.jpg)
Remove posterior pole plasm
Classical Embryology
Remove 5-10% of the anterior cytoplasm
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 16: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/16.jpg)
Properties of the polar center signals
• The anterior and posterior activities inhibit each other
![Page 17: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/17.jpg)
Transplant posterior cytoplasm to anterior
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 18: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/18.jpg)
Transplant anterior cytoplasm to posterior
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 19: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/19.jpg)
Properties of the polar center signals
• Both activities have inductive properties
![Page 20: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/20.jpg)
Transplant anterior cytoplasm to posterior
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 21: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/21.jpg)
Transplant posterior cytoplasm to an anterior that lacks the anterior signal
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 22: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/22.jpg)
What you may know already
Bicoid: Anterior signal
Nanos: Posterior signal
How do we know this?
![Page 23: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/23.jpg)
Maternal effect screens
bcd/bcd mother
Normal egg
Larva missing a head
![Page 24: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/24.jpg)
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 25: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/25.jpg)
Three classes of maternal effect phenotypes
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 26: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/26.jpg)
The real cuticles
wt bcd oskar torso
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 27: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/27.jpg)
Mutant combinations
St Johnston and Nusslein-VolhardCell 1992
![Page 28: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/28.jpg)
Transplantation of cytoplasm into bcd mutants
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 29: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/29.jpg)
Controlling anterior posterior polarity
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 30: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/30.jpg)
The difference between the posterior and anterior signals
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 31: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/31.jpg)
Distinct Properties of the signals
• Anterior signal-instructive. Induces polarity at site of injection.
• Posterior signal-permissive. Polarity independent of injection site.
![Page 32: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/32.jpg)
Evidence for Bicoid
• Rescue activity spatially distributed
• Amount of rescue dependent on amount injected
• Linear relationship between gene dose and rescue activity
• mRNA asymmetrically localized and protein expressed in a gradient
![Page 33: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/33.jpg)
Bicoid rescue assay
Nusslein-Volhard et al., Science 238, 1675-1681
![Page 34: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/34.jpg)
% rescueactivity
100%
50%
% egg length100% 0%40%
Rescue activity is spatially distributed
![Page 35: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/35.jpg)
% rescue activity
0 1/3 2/3 1
Amount of rescue is dependent on amount injected
100%
50%
Transplanted volume
![Page 36: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/36.jpg)
Linear relationship between gene dose and rescue activity
100%
50%
0 1 2 3
% rescue activity
Dose of bicoid gene in mothers
![Page 37: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/37.jpg)
![Page 38: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/38.jpg)
mRNA assymetrically localized and protein expressed in a gradient
mRNA
Protein
Driever and Nusslein-Volhard Cell 54, 83-93
![Page 39: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/39.jpg)
Bicoid
• Bicoid has the properties of the anterior signal
• Does Bicoid need to interact with any other anteriorly localized signals to work?
![Page 40: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/40.jpg)
![Page 41: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/41.jpg)
Bicoid is necessary and sufficient
Bicoid mRNA made in vitro
mRNA injected at posterior pole
Bicoid protein expression
Larva with two heads
Driever et al., 1990 Development 109, 811-820
![Page 42: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/42.jpg)
Bicoid
• Bicoid is the anterior signal
• What does Bicoid encode?
• How does Bicoid work?
![Page 43: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/43.jpg)
Bicoid encodes a homeodomain containing protein.
![Page 44: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/44.jpg)
Hunchback lacks anterior segments
Nusslein-Volhard and Wieschaus 1980 Nature 287, 795
![Page 45: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/45.jpg)
Bicoid mRNA
Bicoid protein
Hunchback mRNAexpression
Hunchback is expressed at the anterior pole
Driever 1993
![Page 46: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/46.jpg)
Hunchback gene
Driever and Nusslein-Volhard Nature 337, 138-143
![Page 47: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/47.jpg)
Bicoid is a transcriptional activator
Driever and Nusslein-Volhard Nature 337, 138-143
![Page 48: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/48.jpg)
mRNA assymetrically localized and protein expressed in a gradient
mRNA
Protein
Driever and Nusslein-Volhard Cell 54, 83-93
![Page 49: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/49.jpg)
Morphogen
• Long range action
• Affect polarity
• Concentration dependent
• Different fates at different concentrations
![Page 50: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/50.jpg)
Morphogen
• Long range action
![Page 51: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/51.jpg)
Bicoid mRNA
Bicoid protein
Hunchback mRNAexpression
Hunchback is expressed at the anterior pole
Driever 1993
![Page 52: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/52.jpg)
Morphogen
• Affect polarity
![Page 53: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/53.jpg)
Bicoid is necessary and sufficient
Bicoid mRNA made in vitro
mRNA injected at posterior pole
Bicoid protein expression
Larva with two heads
Driever et al., 1990 Development 109, 811-820
![Page 54: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/54.jpg)
Morphogen
• Concentration dependent
![Page 55: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/55.jpg)
Concentration dependence of Bicoid function
![Page 56: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/56.jpg)
# of bicoid genes in the mother
1
2
0
4
6
hb-lacZ expression
Concentration dependence of Bicoid function
Struhl et al., 1989 Cell 57, 1259-1273
![Page 57: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/57.jpg)
Morphogen
• Different fates at different concentrations
![Page 58: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/58.jpg)
Distinct Bicoid binding sites are activated at different concentrations of Bicoid
![Page 59: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/59.jpg)
![Page 60: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/60.jpg)
Morphogen
• Long range action
• Affect polarity
• Concentration dependent
• Different fates at different concentrations
![Page 61: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/61.jpg)
How is bicoid mRNA localized to the anterior pole?
![Page 62: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/62.jpg)
![Page 63: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/63.jpg)
Other anterior class mutants
Driever and Nusslein-Volhard Cell 54, 94-104
![Page 64: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/64.jpg)
Bicoid gradient affected in the mutants
Driever and Nusslein-Volhard Cell 54, 94-104
![Page 65: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/65.jpg)
The mutants affect different stages of bicoid mRNA deposition in the developing oocyte
St. Johnston et al., 1989 Development sup 13-19
![Page 66: Lecture 5 Anterior Posterior axis formation: Cell Biology Bicoid is a morphogen.](https://reader036.fdocuments.in/reader036/viewer/2022062803/56649c805503460f949376ad/html5/thumbnails/66.jpg)
Localization of bicoid mRNA: recent paper
Irion and St Johnston 2007 Nature 445, 554-558