Biology subjects

Nkondjio, C. A.

Publications and source records attributed to Nkondjio, C. A..

3 recordsLinked to original sources

bioRxiv2026

Genomic signatures of selection in Anopheles funestus reveal shared and population-specific adaptive variation across African populations

Insecticide resistance in Anopheles funestus threatens malaria vector control across sub-Saharan Africa, yet genomic signatures of selection across geographically structured populations remain poorly understood. We analysed whole-genome sequence data from 635 An. funestus mosquitoes from West (Senegal, Guinea, Nigeria), Central (Cameroon), and East Africa (Kenya) to characterise population structure and identify targets of recent positive selection. Population genomic analyses revealed strong differentiation between East African and West/Central African populations, with finer-scale structuring within West Africa. Genome-wide selection scans using H12 identified sweep regions on chromosome arms 2RL and 3RL, overlapping a cytochrome P450 cluster and the gamma-aminobutyric acid (GABA) receptor locus respectively. iSAFE prioritised candidate variants within these sweeps: non-synonymous substitutions in CYP6A14 were identified at high frequencies in Guinea, Nigeria, and Cameroon, while population-restricted variants implicated octopamine receptor genes on 2RL and the GABA receptor on 3RL. Diplotype clustering and copy number variation analyses confirmed the causal role of candidate variants, embedded within extended haplotypes of reduced heterozygosity consistent with recent positive selection. These findings demonstrate that adaptive evolution in An. funestus reflects both shared and population-specific selective processes shaped by geography and ecological context. Whereas selection on detoxification pathways appears widespread, localised signals in neuromodulatory loci, including the GABA receptor and octopamine-related genes, reveal that biological systems beyond metabolic resistance contribute to mosquito adaptation. The convergence of selective signals across these gene classes highlights neuromodulatory pathways as potential complementary targets for next-generation vector control strategies.

genomics↗

bioRxiv2025

Optimising the use of Oxford Nanopore Sequencing technology for detection of Wolbachia bacterial endosymbionts in Anopheles mosquitoes.

Malaria, a mosquito-borne disease predominantly affecting sub-Saharan Africa, remains a significant global health challenge with 263 million cases in 2023. Although progress in vaccine development has recently occurred, insecticide resistance has reduced the effectiveness of the main stay method of traditional vector control and novel innovative vector control strategies against Anopheles mosquitoes is crucial to combat the spread of malaria. Wolbachia is an endosymbiotic bacterium that can invade mosquito populations and inhibit human pathogens. Historically Wolbachia was thought to not occur naturally within wild Anopheles An.) populations, but recent evidence has confirmed the presence of at least two strains in genuine symbiosis. Detection of Wolbachia strains has pre-dominantly relied on PCR amplification of Wolbachia genes and/or sanger and illumina sequencing. In this study, we assess the use of Oxford Nanopore Technology (ONT) for detecting bacteria within wild Anopheles mosquitoes and determine the ability to detect the endosymbiotc bacterium Wolbachia. We assessed Wolbachia detection from library preparations using the ONT Field sequencing kit for MinION sequencing on the Mk1C and found a pool size of 10 mosquitoes is required preventing individual mosquito analysis. There were roughly 13 times more Wolbachia reads in pooled Anopheles demeilloni compared to An. gambiae. Utilizing the more economical Flongle flow cells and Mk1B device, we further evaluated the effectiveness of two library preparation methods that are compatible: Rapid PCR Barcoding and 16S Barcoding kits. Our findings indicate that the 16S Barcoding Kit in conjunction with the Flongle flowcell effectively identified Wolbachia in both Anopheles demeilloni and Anopheles moucheti but we found no evidence of Wolbachia in Anopheles gambiae. Our study demonstrates the feasibility of developing ONT for field-based sequencing in malaria-endemic regions, providing a potentially lower cost and field friendly method for monitoring mosquito populations and associated endosymbionts. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=196 SRC="FIGDIR/small/659891v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@18ee91dorg.highwire.dtl.DTLVardef@16a71c4org.highwire.dtl.DTLVardef@15330edorg.highwire.dtl.DTLVardef@b13e3d_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2020

Genomic and microscopic evidence of stable high density and maternally inherited Wolbachia infections in Anopheles mosquitoes

Wolbachia, a widespread bacterium that can reduce pathogen transmission in mosquitoes, has been detected within populations of Anopheles (An.) malaria vectors. In the An. gambiae complex, the primary vectors in Sub-Saharan Africa, Wolbachia strains are at low density and infection frequencies in wild populations. PCR-independent evidence is required to determine whether Wolbachia strains are true endosymbionts in Anopheles given most studies to date have used nested-PCR to identify strains. Here we report high-density strains found in geographically diverse populations of An. moucheti and An. demeilloni. Fluorescent in situ hybridization localized a heavy infection in the ovaries of An. moucheti and maternal transmission was observed. Genome sequencing of both strains obtained genome depths and coverages comparable to other known infections. Notably, homologs of cytoplasmic incompatibility factor (cif) genes were present indicating these strains possess the capacity to induce the phenotype cytoplasmic incompatibility which allows Wolbachia to spread through populations. The characteristics of these two strains suggest they are ideal candidates for Wolbachia biocontrol strategies in Anopheles.

microbiology↗