TY - JOUR
T1 - Low species barriers in halophilic archaea and the formation of recombinant hybrids
AU - Naor, Adit
AU - Lapierre, Pascal
AU - Mevarech, Moshe
AU - Papke, R. Thane
AU - Gophna, Uri
N1 - Funding Information:
The authors would like to thank W. Ford Doolittle and J. Peter Gogarten for critical reading of the manuscript, Martin Kupiec for excellent advice and discussion, T. Allers for providing H. volcanii strains and instructive comments, and Jonathan A. Eisen for providing H. mediterranei genomic data. This work was funded by the U.S.–Israel Binational Science Foundation to U.G. and R.T.P. (award number 2007043) and the National Science Foundation (award numbers, 0919290 and 0830024) to R.T.P.
PY - 2012/8/7
Y1 - 2012/8/7
N2 - Speciation of sexually reproducing organisms requires reproductive barriers. Prokaryotes reproduce asexually but often exchange DNA by lateral gene transfer mechanisms and recombination [1], yet distinct lineages are still observed. Thus, barriers to gene flow such as geographic isolation, genetic incompatibility or a physiological inability to transfer DNA represent potential underlying mechanisms behind preferred exchange groups observed in prokaryotes [2-6]. In Bacteria, experimental evidence showed that sequence divergence impedes homologous recombination between bacterial species [7-11]. Here we study interspecies gene exchange in halophilic archaea that possess a parasexual mechanism of genetic exchange that is functional between species [12, 13]. In this process, cells fuse forming a diploid state containing the full genetic repertoire of both parental cells, which facilitates genetic exchange and recombination. Later, cells separate, occasionally resulting in hybrids of the parental strains [14]. We show high recombination frequencies between Haloferax volcanii and Haloferax mediterranei, two species that have an average nucleotide sequence identity of 86.6%. Whole genome sequencing of Haloferax interspecies hybrids revealed the exchange of chromosomal fragments ranging from 310Kb to 530Kb. These results show that recombination barriers may be more permissive in halophilic archaea than they are in bacteria.
AB - Speciation of sexually reproducing organisms requires reproductive barriers. Prokaryotes reproduce asexually but often exchange DNA by lateral gene transfer mechanisms and recombination [1], yet distinct lineages are still observed. Thus, barriers to gene flow such as geographic isolation, genetic incompatibility or a physiological inability to transfer DNA represent potential underlying mechanisms behind preferred exchange groups observed in prokaryotes [2-6]. In Bacteria, experimental evidence showed that sequence divergence impedes homologous recombination between bacterial species [7-11]. Here we study interspecies gene exchange in halophilic archaea that possess a parasexual mechanism of genetic exchange that is functional between species [12, 13]. In this process, cells fuse forming a diploid state containing the full genetic repertoire of both parental cells, which facilitates genetic exchange and recombination. Later, cells separate, occasionally resulting in hybrids of the parental strains [14]. We show high recombination frequencies between Haloferax volcanii and Haloferax mediterranei, two species that have an average nucleotide sequence identity of 86.6%. Whole genome sequencing of Haloferax interspecies hybrids revealed the exchange of chromosomal fragments ranging from 310Kb to 530Kb. These results show that recombination barriers may be more permissive in halophilic archaea than they are in bacteria.
UR - http://www.scopus.com/inward/record.url?scp=84864615070&partnerID=8YFLogxK
U2 - 10.1016/j.cub.2012.05.056
DO - 10.1016/j.cub.2012.05.056
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AN - SCOPUS:84864615070
SN - 0960-9822
VL - 22
SP - 1444
EP - 1448
JO - Current Biology
JF - Current Biology
IS - 15
ER -