Dataset Information

Clarification of anomalies in the application of a 2La molecular karyotyping method for the malaria vector Anopheles gambiae.

ABSTRACT: Chromosomal inversions have been considered to be potentially important barriers to gene flow in many groups of animals through their effect on recombination suppression in heterokaryotypic individuals. Inversions can also enhance local adaptation in different groups of organisms and may often represent species-specific differences among closely related taxa. We conducted a study to characterize the 2La inversion karyotypes of An. gambiae sensu stricto mosquitoes sampled from the Kilombero Valley (Tanzania) using a newly designed PCR assay.We frequently encountered a (687 bp) fragment which was only present in the Kilombero Valley populations. Laboratory crossing between An. gambiae s.s. from Njage (Tanzania) and Kisumu (Western Kenya) populations resulted in F1 offspring carrying the observed fragment. Karyotype analysis did not indicate differences in 2La region chromosome morphology between individuals carrying the PCR fragments, the 207 bp fragment, or the 687 bp fragement.The observed insertion/deletion polymorphism within the region amplified by the 2La PCR diagnostic test may confound the interpretation of this assay and should be well considered in order to maintain an acceptable level of reliability in studies using this assay to describe the distribution and frequency of the 2La inversion among natural populations of An. gambiae s.s.

SUBMITTER: Ng'habi KR

PROVIDER: S-EPMC2628339 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature

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Clarification of anomalies in the application of a 2La molecular karyotyping method for the malaria vector Anopheles gambiae.

Ng'habi Kija R KR Meneses Claudio R CR Cornel Anthony J AJ Slotman Michel A MA Knols Bart Gj BG Ferguson Heather M HM Lanzaro Gregory C GC

Parasites & vectors 20081217 1

<h4>Unlabelled</h4><h4>Background</h4>Chromosomal inversions have been considered to be potentially important barriers to gene flow in many groups of animals through their effect on recombination suppression in heterokaryotypic individuals. Inversions can also enhance local adaptation in different groups of organisms and may often represent species-specific differences among closely related taxa. We conducted a study to characterize the 2La inversion karyotypes of An. gambiae sensu stricto mosqu ...[more]

PMID: 19091112

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Project description:Changes in global temperature are impacting the spread/intensity of vector-borne diseases, including malaria, and accelerating evolutionary/adaptive changes in vector species. These changes, including chromosomal inversions and overexpression and/or changes in allele frequencies of thermotolerance-associated genes, may facilitate insecticide resistance through pleiotropy. This study investigated the impact of thermotolerance on pyrethroid resistance in four populations of the malaria vector An. gambiae s.l., from the savanna/sub-Sahel of northern Nigeria. Anopheles coluzzii and An. gambiae s.s. were the only malaria vectors found, sympatric in all the sites, with the former species predominant. High thermotolerance was observed, with no mortality at 38 °C, and LT50 of ~44 °C. Significantly high permethrin resistance was observed (mortality < 50%) in 44 °C heat-hardened (exposure to an intermediately high temperature provides protection to a more severe temperature or insecticide) larvae from two sites, BUK and Pantami, compared with the control, and heat-hardened adult females from Auyo (mortality = 3.00% ± 1.20, χ2 = 5.83, p < 0.01) compared with the control (12.00% ± 4.65). The 2La chromosomal inversion was detected at ~50% in subset of larvae and 58% in subset of adult females genotyped. A significant association was observed (OR = 7.2, p < 0.03) between permethrin resistance and the 2La/+a rearrangement compared with 2L+a/+a, in BUK larvae. For all sites, permethrin resistance correlated with 2La/a homozygosity in adult females (R = 5.02, p = 0.01). qRT-PCR identified six genes commonly induced/overexpressed, including the heat shock protein 70 (AGAP004581) which was 2468× and 5× overexpressed in heat-hardened and permethrin-resistant females, respectively; trehalose-6-phosphate synthase (AGAP008227); and the ionotropic glutamate receptor genes, IR25a (AGAP010272) and IR21a (AGAP008511). This study highlights challenges associated with insecticide-based malaria vector control, and the epidemiological significance of taking climate variables into account for the design/choice of control measures.

Dataset Information

Clarification of anomalies in the application of a 2La molecular karyotyping method for the malaria vector Anopheles gambiae.

Publications

Clarification of anomalies in the application of a 2La molecular karyotyping method for the malaria vector Anopheles gambiae.

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