P elements and MITE relatives in the whole genome sequence of Anopheles gambiae.
BACKGROUND
Miniature Inverted-repeat Terminal Elements (MITEs), which are particular class-II transposable elements (TEs), play an important role in genome evolution, because they have very high copy numbers and display recurrent bursts of transposition. The 5' and 3' subterminal regions of a given MITE family often show a high sequence similarity with the corresponding regions of an autonomous Class-II TE family. However, the sustained presence over a prolonged evolutionary time of MITEs and TE master copies able to promote their mobility has been rarely reported within the same genome, and this raises fascinating evolutionary questions.


RESULTS
We report here the presence of P transposable elements with related MITE families in the Anopheles gambiae genome. Using a TE annotation pipeline we have identified and analyzed all the P sequences in the sequenced A. gambiae PEST strain genome. More than 0.49% of the genome consists of P elements and derivates. P elements can be divided into 9 different subfamilies, separated by more than 30% of nucleotide divergence. Seven of them present full length copies. Ten MITE families are associated with 6 out of the 9 Psubfamilies. Comparing their intra-element nucleotide diversities and their structures allows us to propose the putative dynamics of their emergence. In particular, one MITE family which has a hybrid structure, with ends each of which is related to a different P-subfamily, suggests a new mechanism for their emergence and their mobility.


CONCLUSIONS
This work contributes to a greater understanding of the relationship between full-length class-II TEs and MITEs, in this case P elements and their derivatives in the genome of A. gambiae. Moreover, it provides the most comprehensive catalogue to date of P-like transposons in this genome and provides convincing yet indirect evidence that some of the subfamilies have been recently active.
Quesneville
Hadi
H
Dynamique du Génome et Evolution, Institut Jacques Monod, CNRS, Universités P,M, Curie and D, Diderot 2, Place Jussieu, 75252 Paris, France. hq@ccr.jussieu.fr
Nouaud
Danielle
D
Anxolabéhère
Dominique
D
D000818:Animals; D000852:Anopheles / Q000235:genetics*; D001482:Base Composition; D001483:Base Sequence; D015139:Blotting, Southern; D004251:DNA Transposable Elements / Q000235:genetics*; D030541:Databases, Genetic; D019143:Evolution, Molecular; D018628:Gene Dosage; D049750:Genome, Insect / Q000235:genetics*; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D017422:Sequence Analysis, DNA / Q000379:methods; D012689:Sequence Homology, Nucleic Acid; D012984:Software
D004251:DNA Transposable Elements