Smelt was the likely beneficiary of an antifreeze gene laterally transferred between fishes

BMC Evolutionary Biology

Research Article

Laurie A Graham¹  Peter L Davies¹  William S Davidson²  Jieying Li² 

[1] Department of Biomedical and Molecular Sciences, Queen’s University, K7L 3N6, Kingston, ON, Canada;Department of Molecular Biology and Biochemistry, Simon Fraser University, V5A 1S6, Burnaby, BC, Canada;

关键词: Ice-binding;    Horizontal gene transfer;    Antifreeze protein;    Osmerus mordax;   

DOI  :  10.1186/1471-2148-12-190

 received in 2012-05-08, accepted in 2012-08-20,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundType II antifreeze protein (AFP) from the rainbow smelt, Osmerus mordax, is a calcium-dependent C-type lectin homolog, similar to the AFPs from herring and sea raven. While C-type lectins are ubiquitous, type II AFPs are only found in a few species in three widely separated branches of teleost fishes. Furthermore, several other non-homologous AFPs are found in intervening species. We have previously postulated that this sporadic distribution has resulted from lateral gene transfer. The alternative hypothesis, that the AFP evolved from a lectin present in a shared ancestor and that this gene was lost in most species, is not favored because both the exon and intron sequences are highly conserved.ResultsHere we have sequenced and annotated a 160 kb smelt BAC clone containing a centrally-located AFP gene along with 14 other genes. Quantitative PCR indicates that there is but a single copy of this gene within the smelt genome, which is atypical for fish AFP genes. The corresponding syntenic region has been identified and searched in a number of other species and found to be devoid of lectin or AFP sequences. Unlike the introns of the AFP gene, the intronic sequences of the flanking genes are not conserved between species. As well, the rate and pattern of mutation in the AFP gene are radically different from those seen in other smelt and herring genes.ConclusionsThese results provide stand-alone support for an example of lateral gene transfer between vertebrate species. They should further inform the debate about genetically modified organisms by showing that gene transfer between ‘higher’ eukaryotes can occur naturally. Analysis of the syntenic regions from several fishes strongly suggests that the smelt acquired the AFP gene from the herring.

【 授权许可】

Unknown   
© Graham et al.; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.