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Identification of an intact ParaHox cluster with temporal colinearity but altered spatial colinearity in the hemichordate Ptychodera flava
- Source :
- BMC Evolutionary Biology
- Publication Year :
- 2013
-
Abstract
- Background ParaHox and Hox genes are thought to have evolved from a common ancestral ProtoHox cluster or from tandem duplication prior to the divergence of cnidarians and bilaterians. Similar to Hox clusters, chordate ParaHox genes including Gsx, Xlox, and Cdx, are clustered and their expression exhibits temporal and spatial colinearity. In non-chordate animals, however, studies on the genomic organization of ParaHox genes are limited to only a few animal taxa. Hemichordates, such as the Enteropneust acorn worms, have been used to gain insights into the origins of chordate characters. In this study, we investigated the genomic organization and expression of ParaHox genes in the indirect developing hemichordate acorn worm Ptychodera flava. Results We found that P. flava contains an intact ParaHox cluster with a similar arrangement to that of chordates. The temporal expression order of the P. flava ParaHox genes is the same as that of the chordate ParaHox genes. During embryogenesis, the spatial expression pattern of PfCdx in the posterior endoderm represents a conserved feature similar to the expression of its orthologs in other animals. On the other hand, PfXlox and PfGsx show a novel expression pattern in the blastopore. Nevertheless, during metamorphosis, PfXlox and PfCdx are expressed in the endoderm in a spatially staggered pattern similar to the situation in chordates. Conclusions Our study shows that P. flava ParaHox genes, despite forming an intact cluster, exhibit temporal colinearity but lose spatial colinearity during embryogenesis. During metamorphosis, partial spatial colinearity is retained in the transforming larva. These results strongly suggest that intact ParaHox gene clustering was retained in the deuterostome ancestor and is correlated with temporal colinearity.
- Subjects :
- Colinearity
Zoology
ParaHox
Chordate
Hemichordate
Evolution, Molecular
03 medical and health sciences
0302 clinical medicine
Chordata, Nonvertebrate
medicine
Animals
Hox gene
Ecology, Evolution, Behavior and Systematics
Phylogeny
030304 developmental biology
Homeodomain Proteins
0303 health sciences
Deuterostome
Genome
biology
biology.organism_classification
medicine.anatomical_structure
Ptychodera Flava
Evolutionary biology
Multigene Family
Tandem exon duplication
Acorn worm
Endoderm
030217 neurology & neurosurgery
Research Article
Subjects
Details
- ISSN :
- 14712148
- Volume :
- 13
- Database :
- OpenAIRE
- Journal :
- BMC evolutionary biology
- Accession number :
- edsair.doi.dedup.....944ef09bf3b2b0d57ae1949b5630a03a