The chordate ParaHox cluster
Abstract
The ParaHox gene cluster is an evolutionary sister to the Hox cluster, which is involved in patterning the anterior-posterior axis of animals. First discovered in the cephalochordate amphioxus (Branchiostoma floridae) [1], the ParaHox gene cluster is thought to have arisen by duplication of an ancestral homeobox gene cluster that produced the ParaHox and Hox clusters, respectively [1,2]. While the Hox cluster is widely conserved among animals, ParaHox clusters are only known from some chordates [1,3]. The detailed organisation of these clusters has not been examined. The amphioxus ParaHox cluster contains three homeobox genes, AmphiGsx, AmphiXlox and AmphiCdx. These genes are expressed along the anterior-posterior axis of amphioxus in the central nervous system and gut, in a fashion that is colinear with their order along the chromosome [1]. To gain a deeper understanding of the ParaHox cluster we have sequenced over 100kb encompassing the complete cluster of amphioxus. Comparing this sequence to the orthologous regions in the genomes of mice and humans reveals that these clusters are not merely an association of three genes, but exhibit a higher order of conservation and maintain the overall organisation, relative gene size and spacing. Furthermore, we show that the mammalian ParaHox cluster is the single remnant of four ancestral clusters.
- Publication:
-
Current Biology
- Pub Date:
- October 2005
- DOI:
- 10.1016/j.cub.2005.10.014
- Bibcode:
- 2005CBio...15.R820F