Recent amplification of miniature inverted-repeat transposable elements in the vector mosquito Culex pipiens: characterization of the Mimo family.
We describe a new family of repetitive elements, named Mimo, from the mosquito Culex pipiens. Structural characteristics of these elements fit well with those of miniature inverted-repeat transposable elements (MITEs), which are ubiquitous and highly abundant in plant genomes. The occurrence of Mimo in C. pipiens provides new evidence that MITEs are not restricted to plant genomes, but may be widespread in arthropods as well. The copy number of Mimo elements in C. pipiens ( approximately 1000 copies in a 540Mb genome) supports the hypothesis that there is a positive correlation between genome size and the magnitude of MITE proliferation. In contrast to most MITE families described so far, members of the Mimo family share a high sequence conservation, which may reflect a recent amplification history in this species. In addition, we found that Mimo elements are a frequent nest for other MITE-like elements, suggesting that multiple and successive MITE transposition events have occurred very recently in the C. pipiens genome. Despite evidence for recent mobility of these MITEs, no element has been found to encode a protein; therefore, we do not know how they have transposed and have spread in the genome. However, some sequence similarities in terminal inverted-repeats suggest a possible filiation of some of these mosquito MITEs with pogo-like DNA transposons.
Feschotte
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Laboratoire Ecologie Moléculaire and Faculté Sciences et Techniques Côte-Basque, Université de Pau et des Pays de l'Adour, Pau, France.
Mouchès
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D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D017124:Conserved Sequence; D003465:Culex / Q000235:genetics*; D004247:DNA / Q000737:chemistry / Q000235:genetics; D004251:DNA Transposable Elements / Q000235:genetics*; D005784:Gene Amplification; D018628:Gene Dosage; D007303:Insect Vectors / Q000235:genetics*; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
D004251:DNA Transposable Elements; D004247:DNA