Widespread horizontal transfer of retrotransposons
Ali Morton Walsha, R. Daniel Kortschaka, Michael G. Gardnerb,c, Terry Bertozzia,c, and David L. Adelsona,1
Author Affiliations
aSchool of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia;
bSchool of Biological Sciences, Flinders University, Adelaide, SA 5005, Australia; and
cEvolutionary Biology Unit, South Australian Museum, Adelaide, SA 5000, Australia
Edited by W. Ford Doolittle, Dalhousie University, Halifax, NS, Canada, and approved December 5, 2012 (received for review April 6, 2012)
Abstract
In higher organisms such as vertebrates, it is generally believed that lateral transfer of genetic information does not readily occur, with the exception of retroviral infection. However, horizontal transfer (HT) of protein coding repetitive elements is the simplest way to explain the patchy distribution of BovB, a long interspersed element (LINE) about 3.2 kb long, that has been found in ruminants, marsupials, squamates, monotremes, and African mammals. BovB sequences are a major component of some of these genomes. Here we show that HT of BovB is significantly more widespread than believed, and we demonstrate the existence of two plausible arthropod vectors, specifically reptile ticks. A phylogenetic tree built from BovB sequences from species in all of these groups does not conform to expected evolutionary relationships of the species, and our analysis indicates that at least nine HT events are required to explain the observed topology. Our results provide compelling evidence for HT of genetic material that has transformed vertebrate genomes.
transposon interspersed repeat
Footnotes
1To whom correspondence should be addressed. E-mail: david.adelson@adelaide.edu.au.
Author contributions: A.M.W. and D.L.A. designed research; A.M.W. and T.B. performed research; A.M.W., R.D.K., M.G.G., and T.B. contributed new reagents/analytic tools; A.M.W., R.D.K., T.B., and D.L.A. analyzed data; and A.M.W., R.D.K., M.G.G., T.B., and D.L.A. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
Data deposition: The survey sequence data have been deposited in the Dryad database, http://datadryad.org [doi nos.: 10.5061/dryad.f1cb2/23 (Amphibolurus norrisi), 10.5061/dryad.f1cb2/46 (Eremiascincus richardsonii), 10.5061/dryad.f1cb2/47 (Glaphyromorphus douglasi), 10.5061/dryad.f1cb2/26 (Gehyra variegate), 10.5061/dryad.f1cb2/27 (Gehyra lazelli), 10.5061/dryad.f1cb2/6 (Bothriocroton hydrosauri), 10.5061/dryad.f1cb2/28 (Hydrophis spiralis), 10.5061/dryad.f1cb2/15 (Isoodon obesulus), 10.5061/dryad.f1cb2/16 (Macrotis lagotis), and 10.5061/dryad.f1cb2/19 (Petaurus breviceps)]; and European Bioinformatics Institute Sequence Read Archive (EBI SRA), http://www.ebi.ac.uk/ena/ (accession nos. ERS195148 [Tiliqua rugosa (Sleepy Lizard) paired end reads], ERS195147 [Egernia stokesii (Skink) paired end reads], and ERS154930 [Tachyglossus aculeatus (Echidna) paired end reads], validation sequences deposited in GenBank with accession nos. KC352670, KC352671, KC352672, KC352673, and KC352674).
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1205856110/-/DCSupplemental.
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