Breakpoint structure of the Anopheles gambiae 2R b chromosomal inversion

• Published in: Malaria Journal
• Main Authors: Costantini Carlo, Traore Sekou F, Emrich Scott J, Sharakhova Maria V, Bretz David A, Reidenbach Kyanne R, Regier Allison A, Sangaré Djibril M, Lobo Neil F, Besansky Nora J, Collins Frank H
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2010
• Subjects: Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/1475-2875-9-293; https://doaj.org/article/9ebcb789af9a4e9eb4673daebbc20488

Abstract Background Alternative arrangements of chromosome 2 inversions in Anopheles gambiae are important sources of population structure, and are associated with adaptation to environmental heterogeneity. The forces responsible for their origin and maintenance are incompletely understood. Molecular characterization of inversion breakpoints provides insight into how they arose, and provides the basis for development of molecular karyotyping methods useful in future studies. Methods Sequence comparison of regions near the cytological breakpoints of 2Rb allowed the molecular delineation of breakpoint boundaries. Comparisons were made between the standard 2R + b arrangement in the An. gambiae PEST reference genome and the inverted 2R b arrangements in the An. gambiae M and S genome assemblies. Sequence differences between alternative 2R b arrangements were exploited in the design of a PCR diagnostic assay, which was evaluated against the known chromosomal banding pattern of laboratory colonies and field-collected samples from Mali and Cameroon. Results The breakpoints of the 7.55 Mb 2R b inversion are flanked by extensive runs of the same short (72 bp) tandemly organized sequence, which was likely responsible for chromosomal breakage and rearrangement. Application of the molecular diagnostic assay suggested that 2R b has a single common origin in An. gambiae and its sibling species, Anopheles arabiensis , and also that the standard arrangement (2R + b ) may have arisen twice through breakpoint reuse. The molecular diagnostic was reliable when applied to laboratory colonies, but its accuracy was lower in natural populations. Conclusions The complex repetitive sequence flanking the 2R b breakpoint region may be prone to structural and sequence-level instability. The 2R b molecular diagnostic has immediate application in studies based on laboratory colonies, but its usefulness in natural populations awaits development of complementary molecular tools.