Extensive duplication of the Wolbachia DNA in chromosome four of Drosophila ananassae |
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Authors: | Lisa Klasson Nikhil Kumar Robin Bromley Karsten Sieber Melissa Flowers Sandra H Ott Luke J Tallon Siv G E Andersson Julie C Dunning Hotopp |
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Institution: | .Department of Cell and Molecular Biology, Molecular Evolution, Uppsala University, Uppsala, Sweden ;.Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201 USA ;.Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, MD 21201 USA |
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Abstract: | BackgroundLateral gene transfer (LGT) from bacterial Wolbachia endosymbionts has been detected in ~20% of arthropod and nematode genome sequencing projects. Many of these transfers are large and contain a substantial part of the Wolbachia genome.ResultsHere, we re-sequenced three D. ananassae genomes from Asia and the Pacific that contain large LGTs from Wolbachia. We find that multiple copies of the Wolbachia genome are transferred to the Drosophila nuclear genome in all three lines. In the D. ananassae line from Indonesia, the copies of Wolbachia DNA in the nuclear genome are nearly identical in size and sequence yielding an even coverage of mapped reads over the Wolbachia genome. In contrast, the D. ananassae lines from Hawaii and India show an uneven coverage of mapped reads over the Wolbachia genome suggesting that different parts of these LGTs are present in different copy numbers. In the Hawaii line, we find that this LGT is underrepresented in third instar larvae indicative of being heterochromatic. Fluorescence in situ hybridization of mitotic chromosomes confirms that the LGT in the Hawaii line is heterochromatic and represents ~20% of the sequence on chromosome 4 (dot chromosome, Muller element F).ConclusionsThis collection of related lines contain large lateral gene transfers composed of multiple Wolbachia genomes that constitute >2% of the D. ananassae genome (~5 Mbp) and partially explain the abnormally large size of chromosome 4 in D. ananassae.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-1097) contains supplementary material, which is available to authorized users. |
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Keywords: | Drosophila ananassae Wolbachia Lateral gene transfer Horizontal gene transfer Symbiosis Underreplication Heterochromatin |
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