expansion of tandem gene clusters gene duplication by unequal crossing-over divergence of coding and...
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Expansion of tandem gene clusters
Gene duplication by unequal crossing-over
Divergence of coding and regulatory sequences
Evolution of HOX clusters
The homeobox is a highly conserved DNA-binding domain
DrosophilaAmphioxusMouseHumanChickFrogFugu
Zebrafish
HOX4 homeodomain
Evolution of HOX clusters in vertebrates
Mouse
Fugu
Zebrafish
- Vertebrates have multiple HOX clusters
- Paralogous HOX genes may have partly redundant functions
- Some genes and clusters become specialized for distinct functions
- Different lineages lose some genes and acquire new functions for others
Using gene replacement to test HOX gene function
Using gene replacement to test HOX gene function
Functionally equivalent HOX paralogs
HOX gene labial required for tritocerebral commissure
Genetic rescue strategy
lab-Gal4 lab ; lab-Gal4 / UAS - lab-
red = HRP; green = Lab
Other HOX genes can partially substitute for lab
Other HOX genes can partially substitute for lab
Distinct roles of Ubx and abd-A in the midgut
dpp expression in the fly midgut is activated by Ubx, but repressed by abd-A
Activation and repression are mediated by the same binding sites within a dpp enhancer
Onychophoran Ubx causes homeotic transformations in Drosophila
Onychophoran Ubx can regulate some Drosophila target genes
dSRFdpp
Onychophoran Ubx cannot fully substitute for Drosophila Ubx
Chimeric Ubx proteins
Mapping the functional specificity of Onychophoran Ubx
Functional specificity of Ubx maps outside the homeodomain
Conservation and change in Ubx proteins
Mapping the functional specificity of Ubx proteins
Functional comparison of Drosophila and Artemia Ubx
Evolution of a new repression domain
Non-HOX functions of derived HOX genes
Maternal gradient of bicoid establishes Anterior-Posterior axis in the Drosophila embryo
bicoid gradient formation in Drosophila
zen functions in Dorso-Ventral patterning
sna
sog
zen
zen is a derived HOX gene
HOX-like expression of zen homologue in Cupiennius
Evolution of zen and bcd from an ancestral HOX gene
Genetic control of segmentation in Drosophila
Antennae
ftz deletion does not affect segmentation in Tribolium
HOX-like expression of the Chelicerate ftz homologue
Archegozetes longisetosus
Effects of ectopic ftz expression in Drosophila
Dm
Sg
en expression
36%
4%
A homeodomain-deficient ftz allele
ftz expression in Schistocerca
Tc-ftz
Sg-ftz
Dm-ftz
Tc-ftz
Dll-Gal4
Homeotic antenna to leg transformations
Tribolium ftz retains homeotic potential
wt Dm-ftz Tc-ftz Dm-Scr
wt Dm-ftz Tc-ftz Dm-Antp
Evolution of ftz function
Comparison of ftz proteins between Drosophila and Schistocerca
Expression and function of ftz-F1
ftz-F1 ftz
enftz-F1 mutant
ftz-F1 encodes a nuclear hormone receptor
Physical interaction between ftz and ftz-F1
Transcriptional activation by ftz / ftz-F1 complex
In yeast In Drosophila embryos
Novel functions of divergent HOX genes
Loss and gain of protein-protein interaction motifs