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Lecture 12
• Urbilateria
• Experimental approach to Evo Devo
• Hox proteins
• Eyeless story
Final Examination
• Thursday April 19, 2012 at 9 AM
Is the study of living organisms
the study of the radiation of
Urbilateria?
Carroll et al., From DNA to diversity
A complex organism existed at the
protostome deuterostome split
Carroll et al., From DNA to diversity
Experimental approach
• Conservation of structure
• Conservation of expression
• Conservation of requirement
• Conservation of function (functional
equivalence)
HOX proteins
• Conservation of structure
• Conservation of expression
• Conservation of requirement
• Conservation of function (functional
equivalence)
Drosophila Hox (homeotic) genes
Carroll et al., From DNA to diversity
Structure of the Homeodomian
Gehring et al., Cell 78, 211
Amino acid sequence comparison
of the Drosophila HOX proteins
Carroll et al., From DNA to diversity
Conservation of Hox subclasses
Vertebrate Hox gene complexes
Carroll et al., From DNA to diversity
Comparison between the insect and
vertebrate Hox complexes
Carroll et al., From DNA to diversity
Conservation across animal phyla
Carroll et al., From DNA to diversity
HOX proteins
• Conservation of structure
• Conservation of expression
• Conservation of requirement
• Conservation of function (functional
equivalence)
Hox expression in Drosophila
Carroll et al., From DNA to diversity
Phylogenetic relationships between major
Arthropod groups
Carroll et al., From DNA to diversity
Conservation of Hox expression in
Arthropods
Carroll et al., From DNA to diversity
Conservation of Hox expression in
Annelids
Carroll et al., From DNA to diversity
Conservation of general pattern of Hox
expression in vertebrates
Carroll et al., From DNA to diversity
Expression of anterior Hox genes
Carroll et al., From DNA to diversity
HOX proteins
• Conservation of structure
• Conservation of expression
• Conservation of requirement
• Conservation of function (functional
equivalence)
Antennapedia can be misexpressed either by spontaneous
mutation or by genetic engineering.
+
Antp
ry
hsp
Antenna to second leg transformation
The classic Ultrabithorax phenotype:
the four winged fly
wild type
Ubx
Spontaneous homeosis
W. Bateson 1894 Materials for the study of variation
Hoxa-5 null mutants
Jeannotte et al., Genes and Dev. 7, 2085
Jeannotte et al., Genes and Dev. 7, 2085
The classic Ultrabithorax phenotype:
posterior to anterior transformation
wild type
Ubx
Posterior to anterior transformation in
Hox 11 mutants
Carroll et al., From DNA to diversity
HOX proteins
• Conservation of structure
• Conservation of expression
• Conservation of requirement
• Conservation of function (functional
equivalence)
Functional equivalence of Hoxa5 in
Drosophila
Carroll et al., From DNA to diversity
Hoxa5 and the ectopic expression construct
Zhao et al., Genes and Dev. 7, 343
Ectopic expression of Drosophila SCR
Zhao et al., Genes and Dev. 7, 343
Ectopic expression of mouse Hoxa5
Zhao et al., Genes and Dev. 7, 343
Ectopic expression of Drosophila SCR and
mouse Hoxa5
wild type
hsp Scr
hsp Hoxa5
hsp Hoxa5
Zhao et al., Genes and Dev. 7, 343
Functional equivalence of Hoxb1 in
Drosophila
Carroll et al., From DNA to diversity
Sequence comparisons of the HDs
Lutz et al., Genes and Dev. 10, 176
Rescue of lab phenotype by a mini-lab gene
lab14
;
lab
lab minigene construct
lab14
Construct used to test if chicken
Hoxb1 can rescue the lab phenotype
Lutz et al., Genes and Dev. 10, 176
Rescue
wild type
Hoxb1; lab14
lab14
Lutz et al., Genes and Dev. 10, 176
DPP/b-TGF
• Conservation of structure
• Conservation of expression
• Conservation of requirement
• Conservation of function (functional
equivalence)
Organization of the major animal groups
Raff The shape of life
Deuterostomes and protostomes
Cross section
Expression of dpp and b-TGF
A complex organism existed at the
protostome deuterostome split
Carroll et al., From DNA to diversity
The eyeless/PAX6 story
• Conservation of structure
• Conservation of expression
• Conservation of requirement
• Conservation of function (functional
equivalence)
Sequence similarity of eyeless and Pax-6
The eyeless/PAX6 story
• Conservation of structure
• Conservation of expression
• Conservation of requirement
• Conservation of function (functional
equivalence)
Expression of eyeless
Carroll et al., From DNA to diversity
Expression of eyeless and Pax6
Carroll et al., From DNA to
diversity
Phyogenetic comparison of expression
Carroll et al., From DNA to diversity
The eyeless/PAX6 story
• Conservation of structure
• Conservation of expression
• Conservation of requirement
• Conservation of function (functional
equivalence)
Eyeless is required for
Drosophila eye development
Carroll et al., From DNA to diversity
Pax6 is required for mouse eye development
Carroll et al., From DNA to diversity
Mutations in human Pax6 result in aniridia:
lack of an iris when heterozygous
Aniridia
heterozygous
homozygous
The eyeless/PAX6 story
• Conservation of structure
• Conservation of expression
• Conservation of requirement
• Conservation of function (functional
equivalence)
Binary or two component system
Fly stock A: UAS line
Fly stock B: Driver line
Promoter
YFG
GAL4
or Enhancer
GAL4 binding sites
UASGAL4
GAL4
YFG
Progeny
Ectopic expression of eyeless
Fly stock A: UAS line
eyeless
Fly stock B: Driver line
Promoter
YFG
GAL4
or Enhancer
GAL4 binding sites
UASGAL4
eyeless
GAL4
YFG
Progeny
Ectopic expression of eyeless
Fly stock A: UAS line
eyeless
Fly stock B: Driver line
Promoter
YFG
GAL4
or Enhancer
GAL4 binding sites
UASGAL4
GAL4
eyeless
GAL4
YFG
Progeny
Ectopic expression of eyeless
induces ectopic eye formation
Carroll et al., From DNA to diversity
Ectopic expression of eyeless
induces ectopic eye formation
Halder et al., Science 267, 1788
Ectopic expression of eyeless
induces ectopic eye formation
Halder et al., Science 267, 1788
Ectopic expression of Pax6
induces ectopic eye formation
UAS eyeless
UAS Pax6
Halder et al., Science 267, 1788
A complex organism existed at the
protostome deuterostome split
Carroll et al., From DNA to diversity