Genome biology of the cyclostomes and insights into the evolutionary biology of vertebrate genomes

J. J. Smith, N. R. Saha, C. T. Amemiya

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


The jawless vertebrates (lamprey and hagfish) are the closest extant outgroups to all jawed vertebrates (gnathostomes) and can therefore provide critical insight into the evolution and basic biology of vertebrate genomes. As such, it is notable that the genomes of lamprey and hagfish posses a capacity for rearrangement that is beyond anything known from the gnathostomes. Like the jawed vertebrates, lamprey and hagfish undergo rearrangement of adaptive immune receptors. However, the receptors and the mechanisms for rearrangement that are utilized by jawless vertebrates clearly evolved independently of the gnathostome system. Unlike the jawed vertebrates, lamprey and hagfish also undergo extensive programmed rearrangements of the genome during embryonic development. By considering these fascinating genome biologies in the context of proposed (albeit contentious) phylogenetic relationships among lamprey, hagfish, and gnathostomes, we can begin to understand the evolutionary history of the vertebrate genome. Specifically, the deep shared ancestry and rapid divergence of lampreys, hagfish and gnathostomes is considered evidence that the two versions of programmed rearrangement present in lamprey and hagfish (embryonic and immune receptor) were present in an ancestral lineage that existed more than 400 million years ago and perhaps included the ancestor of the jawed vertebrates. Validating this premise will require better characterization of the genome sequence and mechanisms of rearrangement in lamprey and hagfish.

Original languageEnglish
Pages (from-to)130-137
Number of pages8
JournalIntegrative and Comparative Biology
Issue number1
StatePublished - Jul 2010

Bibliographical note

Funding Information:
This work was supported by the National Institutes of Health [grant number GM079492] and the National Science Foundation [grant number MCB-0719558] to C.T.A. and the National Institutes of Health [grant number T32-HG00035, F32-GM087919] to J.J.S. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NIH.

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Plant Science


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