The Open Virology Journal

2008, 2 : 44-60
Published online 2008 May 7. DOI: 10.2174/1874357900802010044
Publisher ID: TOVJ-2-44

RESEARCH ARTICLE
 Transcriptome Analysis of ESTs from a Chaetognath Reveals a Deep-Branching Clade of Retrovirus-Like Retrotransposons

Roxane M Barthélémy , Jean-Paul Casanova and Eric Faure, *
LATP, CNRS-UMR 6632, Evolution biologique et modélisation, case 5, Université de Provence, Place Victor Hugo, 13331 Marseille cedex 3, France

* Address correspondence to this author at the LATP, CNRS-UMR 6632, Evolution biologique et modélisation, case 5, Université de Provence, Place Victor Hugo, 13331 Marseille cedex 3, France; Tel: 00 (33) 491 10 61 77; Fax: 00 (33) 491 10 62 25; E-mail: eric.faure@univ-provence.fr

ABSTRACT

Chaetognaths constitute a small marine phylum exhibiting several characteristic which are highly unusual in animal genomes, including two classes of both rRNA and protein ribosomal genes. As in this phylum presence of retrovirus-like elements has never been documented, analysis of a published expressed sequence tag (EST) collection of the chaetognath Spadella cephaloptera has been made. Twelve sequences representing transcript sections of reverse transcriptase domain of active retrotransposons were isolated from~11,000 ESTs. Five of them are originated from Gypsy retrovirus-like elements, whereas the other are transcripts from a Bel-Pao LTR-retrotransposon, a Penelope-like element and LINE retrotransposons. Moreover, a part of a putative integrase has also been found. Phylogenetic analyses suggest a deep-branching clade of the retrovirus-like elements, which is in agreement with the probably Cambrian origin of the phylum. Moreover, retrotransposons have not been found in telomeric-like transcripts which are probably constituted by both vertebrate and arthropod canonical repeats.

Keywords:

Retrovirus-like, retrotransposons, Chaetognatha, , reverse transcriptase..