Biology Reference
In-Depth Information
Colinearity
Drosophila melanogaster
embryo, stage 11
lab
Dfd
Scr
Antp
Ubx/abd-A
Abd-B
Temporal colinearity
Mouse embryonic trunk
(early stages)
Hoxd4
Hoxd9
Hoxd13
~ E7.3
~ E7.8
~ E8.8
Spatial colinearity
Mouse embryonic trunk
(later stages)
Hoxd4
Hoxd9
Hoxd13
E10.5
Figure 4.1 Schematics of Hox gene expression in Drosophila and mouse. Top: Collinear
expression domains of Hox genes in stage 11 Drosophila embryo. Middle: Temporal col-
linear expression domains of Hoxd genes in the early embryonic mouse trunk, at differ-
ent stages of embryonic development. Bottom: Overlapping spatial collinear expression
domains of Hoxd genes in the late embryonic mouse trunk. Top panel data is taken from
Kosman et al. (2004)
.
studies focusing on the epigenetic status and the three-dimensional (3D) orga-
nization of
Hox
clusters, combinedwith both reverse genetics and the increased
numbers of available animal genomes, have started to reveal some of the reg-
ulatory rules associated with these mechanisms. In this chapter, we compare
recent insights into these processes obtained fromboth
Drosophila
andmammals
and try to relate these findings to the function and evolution of
Hox
genes.
2. HOX GENE FUNCTION AND GENOMIC ORGANIZATION
Mutations in
Hox
genes of
Drosophila
were originally identified
because of their ability to switch imaginal disk identity during embryonic
development, which resulted in dramatic changes in adult body structures.
