Biology Reference
In-Depth Information
AbdB
AbdA
Ubx
Antp
Scr
Dfd
pb
lab
Drosophila
HOM-C
Hypothetical
common
ancestor
Amphioxus
Hox cluster
10
9
8
7
6
5
4
3
2
1
Mouse Hoxa
a-13
a-11
a-10
a-9
a-7
a-6
a-5
a-4
a-3
a-2
a-1
Mouse Hoxb
b-13
b-9
b-8
b-7
b-6
b-5
b-4
b-3
b-2
b-1
Mouse Hoxc
c-13
c-12
c-11
c-10
c-9
c-8
c-6
c-5
c-4
Mouse Hoxd
d-13
d-12
d-11
d-10
d-9
d-8
d-4
d-3
d-1
Figure 4.16.
Model for the evolution of the homeobox gene clusters of eukaryotes
(redrawn from Holland and Garcia-Fernandez, 1996). In
Drosophila
, the eight
Hox
genes
are found in a single complex which is split between two clusters. AbdB: Abdominal-B.
AbdA: Abdominal-A. Ubx: Ultrabithorax. Antp: Antennapedia. Scr: Sex combs reduced.
Dfd: Deformed. Pb: Proboscipedia. Lab: Labial. In mammals, four
Hox
gene clusters are
found on separate chromosomes.
HOXA
Chrom. 7p
3
1 09
7654321
HOXB
Chrom. 17q
3
987654321
HOXC
Chrom. 12q
13
12
11
10
9
8
6
5
4
HOXD
Chrom. 2q
13
12
11
10
9
8
4
3
1
Figure 4.17.
Human
HOX
gene clusters. Physical distances are not to scale.
HOXC6
,
HOXC8
,
HOXC9
,
HOXC10
,
HOXC11
,
HOXC12,
and
HOXC13
. The
HOX D cluster is located at 2q31-q32 and contains 9 genes:
HOXD1
,
HOXD3
,
HOXD4
,
HOXD8
,
HOXD9
,
HOXD10
,
HOXD11
,
HOXD12,
and
HOXD13
. In
addition to the
HOX
gene clusters, other dispersed paralogous
HOX
genes are
found in the human genome (e.g.
MSX1
, 4p16;
HMX2
, 10q25-q26) and may also
be of functional importance (Brooke
et al
., 1998).
The development of the vertebrate body plan both by elaboration of primitive
chordate characters and the development of novel morphological characters
