Ribosomal Gene Polymorphism in Small Genomes: Analysis of Different 16S rRNA Sequences Expressed in the Honeybee Parasite Nosema ceranae (Microsporidia)

Authors

  • Soledad Sagastume,

    1. Centro Apícola Regional, Bee Pathology Laboratory, Guadalajara, Spain
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  • Raquel Martín-Hernández,

    1. Centro Apícola Regional, Bee Pathology Laboratory, Guadalajara, Spain
    2. Instituto de Recursos Humanos para la Ciencia y la Tecnología (INCRECYT), Parque Científico de Albacete, Spain
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  • Mariano Higes,

    1. Centro Apícola Regional, Bee Pathology Laboratory, Guadalajara, Spain
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  • Nuno Henriques-Gil

    Corresponding author
    1. Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad CEU San Pablo, Madrid, Spain
    • Correspondence

      Nuno Henriques-Gil, Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad CEU San Pablo, Campus de Montepríncipe, 28668 Madrid, Spain

      Telephone number: +34-91-372-4700; FAX number: +34-91-352-0496; e-mail: nhengil@ceu.es

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Abstract

To date, few organisms have been shown to possess variable ribosomal RNA, otherwise considered a classic example of uniformity by concerted evolution. The polymorphism for the 16S rRNA in Nosema ceranae analysed here is striking as Microsporidia are intracellular parasites which have suffered a strong reduction in their genomes and cellular organization. Moreover, N. ceranae infects the honeybee Apis mellifera, and has been associated with the colony-loss phenomenon during the last decade. The variants of 16S rRNA include single nucleotide substitutions, one base insertion-deletion, plus a tetranucleotide indel. We show that different gene variants are expressed. The polymorphic sites tend to be located in particular regions of the rRNA molecule, and the comparison to the Escherichia coli 16S rRNA secondary structure indicates that most variations probably do not preclude ribosomal activity. The fact that the polymorphisms in such a minimal organism as N. ceranae are maintained in samples collected worldwide suggest that the existence of differently expressed rRNA may play an adaptive role in the microsporidian.

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