MBE Advance Access published online on November 7, 2008
Molecular Biology and Evolution, doi:10.1093/molbev/msn260
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Research Article |
Degenerate Tetraploidy Was Established Before Bdelloid Rotifer Families Diverged
1 Harvard University, Department of Molecular and Cellular Biology, 7 Divinity Avenue, Cambridge, MA 02138, USA
2 University of Namur (FUNDP), URBO, 61 Rue de Bruxelles, 5000 Namur, Belgium
3 Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
* To whom correspondence should be addressed: Matthew Meselson, Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, Telephone (617) 495-2264, Fax: (617) 496-2444, E-mail: msm{at}wjh.harvard.edu
Received for publication September 3, 2008. Revision received October 30, 2008. Accepted for publication November 3, 2008.
Rotifers of Class Bdelloidea are abundant freshwater invertebrates known for their remarkable ability to survive desiccation and their lack of males and meiosis. Sequencing and annotation of ca 50 kb regions containing the four hsp82 heat shock genes of the bdelloid Philodina roseola, each located on a separate chromosome, has suggested that its genome is that of a degenerate tetraploid. In order to determine whether a similar structure exists in a bdelloid distantly related to P. roseola and if degenerate tetraploidy was established before the two species separated, we sequenced regions containing the hsp82 genes of a bdelloid belonging to a different family, Adineta vaga, and the canonical histone gene clusters of P. roseola and A. vaga. Our findings are entirely consistent with degenerate tetraploidy and show that it was established before the two bdelloid families diverged and therefore probably before the bdelloid radiation.
Key Words: bdelloid • degenerate tetraploid • hsp82 • histone gene cluster • Adineta vaga • Philodina roseola