Segmental duplication implicated in the genesis of inversion 2Rj of Anopheles gambiae

The malaria vector Anopheles gambiae maintains high levels of inversion polymorphism that facilitate its exploitation of diverse ecological settings across tropical Africa. Molecular characterization of inversion breakpoints is a first step toward understanding the processes that generate and mainta...

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Bibliographic Details
Published in:	PloS one Vol. 2; no. 9; p. e849
Main Authors:	Coulibaly, Mamadou B, Lobo, Neil F, Fitzpatrick, Meagan C, Kern, Marcia, Grushko, Olga, Thaner, Daniel V, Traoré, Sékou F, Collins, Frank H, Besansky, Nora J
Format:	Journal Article
Language:	English
Published:	United States Public Library of Science 05-09-2007 Public Library of Science (PLoS)
Subjects:	Analysis Animals Anopheles Anopheles - genetics Anopheles gambiae Base Sequence Breakpoints Breeding sites Chromosomes Computer applications Evolution Exploitation Gene Duplication Genes, Insect Genetics and Genomics/Chromosome Biology Genomes Genomic instability Genomics In Situ Hybridization, Fluorescence Infectious diseases Insects Insertion Inversion Inversions Inverted repeat Malaria Mating Medical screening Molecular biology Molecular Sequence Data Mosquitoes Polymorphism Polymorphism, Genetic Reproduction (copying) Rivers Sequence Homology, Nucleic Acid Spacer Stability Transposons Vector-borne diseases Vectors (Biology)
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Summary:	The malaria vector Anopheles gambiae maintains high levels of inversion polymorphism that facilitate its exploitation of diverse ecological settings across tropical Africa. Molecular characterization of inversion breakpoints is a first step toward understanding the processes that generate and maintain inversions. Here we focused on inversion 2Rj because of its association with the assortatively mating Bamako chromosomal form of An. gambiae, whose distinctive breeding sites are rock pools beside the Niger River in Mali and Guinea. Sequence and computational analysis of 2Rj revealed the same 14.6 kb insertion between both breakpoints, which occurred near but not within predicted genes. Each insertion consists of 5.3 kb terminal inverted repeat arms separated by a 4 kb spacer. The insertions lack coding capacity, and are comprised of degraded remnants of repetitive sequences including class I and II transposable elements. Because of their large size and patchwork composition, and as no other instances of these insertions were identified in the An. gambiae genome, they do not appear to be transposable elements. The 14.6 kb modules inserted at both 2Rj breakpoint junctions represent low copy repeats (LCRs, also called segmental duplications) that are strongly implicated in the recent (approximately 0.4N(e) generations) origin of 2Rj. The LCRs contribute to further genome instability, as demonstrated by an imprecise excision event at the proximal breakpoint of 2Rj in field isolates.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Conceived and designed the experiments: NB FC MC ST. Performed the experiments: MC OG DT MF MK. Analyzed the data: NB MC NL MF. Contributed reagents/materials/analysis tools: FC NL ST. Wrote the paper: NB MC.
ISSN:	1932-6203 1932-6203
DOI:	10.1371/journal.pone.0000849