title: Low species barriers in halophilic archaea and the formation of recombinant hybrids.
abstract: 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.
authors: Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel.
authors: Adit
authors: A
authors: Naor
authors: Pascal
authors: P
authors: Lapierre
authors: Moshe
authors: M
authors: Mevarech
authors: R Thane
authors: RT
authors: Papke
authors: Uri
authors: U
authors: Gophna
mesh_terms: D019623:Haloferax mediterranei / Q000235:genetics*; D019622:Haloferax volcanii / Q000235:genetics*; D006824:Hybridization, Genetic; D011995:Recombination, Genetic