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Comparative genomics of chondrichthyan Hoxa clusters

Abstract:

Background: The chondrichthyan or cartilaginous fish (chimeras, sharks, skates and rays) occupy an important phylogenetic position as the sister group to all other jawed vertebrates and as an early lineage to diverge from the vertebrate lineage following two whole genome duplication events in vertebrate evolution. There have been few comparative genomic analyses incorporating data from chondrichthyan fish and none comparing genomic information from within the group. We have sequenced the complete Hoxa cluster of the Little Skate (Leucoraja erinacea) and compared to the published Hoxa cluster of the Horn Shark (Heterodontus francisci) and to available data from the Elephant Shark (Callorhinchus milii) genome project.

Results: A BAC clone containing the full Little Skate Hoxa cluster was fully sequenced and assembled. Analyses of coding sequences and conserved non-coding elements reveal a strikingly high level of conservation across the cartilaginous fish, with twenty ultraconserved elements (100%,100 bp) found between Skate and Horn Shark, compared to three between human and marsupials. We have also identified novel potential non-coding RNAs in the Skate BAC clone, some of which are conserved to other species.

Conclusion: We find that the Little Skate Hoxa cluster is remarkably similar to the previously published Horn Shark Hoxa cluster with respect to sequence identity, gene size and intergenic distance despite over 180 million years of separation between the two lineages. We suggest that the genomes of cartilaginous fish are more highly conserved than those of tetrapods or teleost fish and so are more likely to have retained ancestral non-coding elements. While useful for isolating homologous DNA, this complicates bioinformatic approaches to identify chondrichthyan-specific non-coding DNA elements

Publication status:
Published
Peer review status:
Peer reviewed

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Files:
Publisher copy:
10.1186/1471-2148-9-218

Authors


More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Zoology
Role:
Author


Publisher:
BioMed Central
Journal:
BMC Evolutionary Biology More from this journal
Volume:
9
Article number:
218
Publication date:
2009-09-02
Acceptance date:
2009-09-02
DOI:
EISSN:
1471-2148


Language:
English
Keywords:
UUID:
uuid:3cdb0145-7feb-44bd-a74a-bcfeda5cff4e
Local pid:
pubs:204475
Source identifiers:
204475
Deposit date:
2012-12-19

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