Eye
Claw
2nd Axis
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Comparing Eye Development in Flies & Vertebrates: Role of Pax6 & Hox Genes, Slides of Life Sciences
An in-depth analysis of the evolutionary conservation of eye development patterns in flies and mice, focusing on the roles of pax6 genes and hox genes. Topics covered include the evolutionary conservation of neural induction, patterning of the neuroectoderm, and sequential formation of photoreceptor clusters. The document also explores the arguments for and against the idea that eyeless/pax6 is a master gene for eye development.
Typology: Slides
2012/2013
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Download Comparing Eye Development in Flies & Vertebrates: Role of Pax6 & Hox Genes and more Slides Life Sciences in PDF only on Docsity!
Eye
Claw
2nd Axis
Evolutionary Conservation of Hox Expression Patterns
Drosophila
Neuroectoderm
Mouse Neural Tube
Sonic Hh
BMPs
Msx
Nkx2.
Gsh
Dorsal
Dpp
ind
msh
vnd
dpp
Patterning the Neuroectoderm in Flies and Mice
A P
Hh
Dpp
Hh
Hh BMP-
A
P
Fly wing disc
A/PAxis
Vertebrate Limb Bud
D/VAxis
P/DAxis
D V
A P
NotchSignaling
A
P
D V
NotchSignaling
D V
A P
Distalless
A
P
D
V
Distalless
A
P
Specification of the
eye disc in the embryo
1,000-X growth
eyeless
A master eye gene?
Eye Primordium20-40 Cells
Furrow
A
P
Growth and patterning of eye imaginal disc in larvae
dpp
hh
Early Steps in Fly Eye Development
R
8
R
7
Sequential formation ofphotoreceptor clusters Furrow
R^2 R^5
R 3 R 4
R 8
R^1 R^6
R^78
7
3
5
Photoreceptor Development^1
Fly Eye Development
Furrow
A
P
Patterning of theeye imaginal disc
dpp
hh
docsity.com
Opticnerves
Lens
Photoreceptors
Epidermis
Invaginating eyeimaginal disc Eyedisc
Morphogenetic furrow Ant.
Post.
8 7
3
5
PhotoreceptorDevelopment 1
Photoreceptorsinduce lens cells
Furrow
OpticVesicle
Brain
Lens
Retina
Cornea
Opticnerve
Photoreceptors
Iris
Future lens F u tu re retin a
Brain Futurelens Futureretina
Iris
CorneaLens Retina
Opticnerve
Photoreceptors
Iris fold
Lens
Cornealfold
Lens fold
Eye primordium
Migrating lens cells
Future Retina
Comparative Eye Development
Fly
Vertebrate
Squid
Is Eyeless/Pax6 a Master Gene for Eye Development?
Arguments in Favor:
Wild-type Wing
Decreased activity of
pax
genes results in reduced eye size in flies,
mice, and humans.
pax
genes are expressed in the early eye primordia of flies, humans,
and squid, in which eyes were thought to have evolved independently.
Wing Mis-expressing Human
pax
gene
Eye
3) Mis-expression of fly or human pax6 genes in certain fly tissues (e.g.
wing) result in formation of ectopic eyes.
Hox genes
A/P Axis
Abdomen
Head
Tail
Mouth
Anus/ Genitals
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Sog/Chd Dpp/BMP
Non-neural Ectoderm^ Neural Ectoderm
D/V Axis
Photosensitive organs
Sensory Appendages?
Eyespot?
Gills?
Protrusions or appendages
Reconstructing the Common Ancestor of Flies and Humans
What Was So Great About Our the Common Ancestor?