Mbengue, A. | bioRxiv Science

bioRxiv2026

Lack of Evidence for Local Adaptation in Risk Tolerance: A Genetic Study in Northern Senegal.

Risk tolerance is influenced by both environmental and genetic factors and may be shaped by local selective pressures in hazardous environments. In Northern Senegal, fishermen from the village of Guet Ndar are chronically exposed to high occupational mortality risk, making this population a potential model for local adaptation to risky environments. In a previous study, we showed that men from this fishing community were less risk-tolerant than men from a nearby farming village, although this difference could not be explained by variation at the DRD4 locus. Here, we investigated whether genetic variants previously associated with general risk tolerance in large genome-wide association studies (GWAS) exhibit signals of local adaptation in these Senegalese populations. We genotyped 44 candidate SNPs in 373 individuals sampled from the risky fishing area and the non-risky farming area. Population genetic analyses revealed extremely low and non-significant differentiation between the two populations (mean FST = 0.0003, p = 0.33), indicating that the two groups are genetically indistinguishable at these loci. Furthermore, none of the candidate SNPs showed a significant association with experimentally measured risk tolerance after correction for multiple testing. These results provide no evidence that local adaptation for risky behavior has occurred, several explanations may account for this negative result.

evolutionary biology↗

bioRxiv2017

Characterization of polymorphisms in Plasmodium falciparum artemisinin resistance marker kelch13 in asymptomatic infections in a rural area of Cameroon

BackgroundThe genetic variability of the artemisinin resistance (AR) molecular marker kelch13 has been extensively investigated in Plasmodium falciparum malaria parasites from symptomatic infections in South East (SE) Asia where AR is highly prevalent, as well as in Africa where evidence of AR has emerged only recently. However, molecular surveillance and risk of transmission of AR also require monitoring asymptomatic infection. Here, molecular analyses were used to investigate polymorphisms in kelch13 and their potential for transmission in asymptomatic adults in Bolifamba, Cameroon in Central Africa.\n\nMethodsUsing polymerase chain reaction (PCR), we amplified and sequenced the full length of kelch13 from P. falciparum infections detected in the blood of 33 asymptomatic adults (age: 18-55 years-old) collected in a cross-sectional study from July 2008 to October 2009. Risk of increased transmission was assessed by quantifying gametocytes by qPCR. Quantitative ELISA was used to detect plasma levels of PfHRP2 to establish total parasite burdens associated with asymptomatic infection.\n\nResultsOut of 33 isolates tested, 14 (42.4%) presented at least a single nucleotide polymorphism (SNP) in kelch13. Five non-synonymous SNPs were detected (K189T/N, N217H, R393K and E433K). None were located in the beta-propeller domain, where AR mutations have been detected in both SE Asian and, more recently, African parasites. K189T/N and N217H have been previously reported in African strains, but R393K and E433K are new polymorphisms. Gametocytes were detected in 24.2% of infections, without a significant association with detected Kelch13 polymorphisms. Notably, polymorphisms detected in kelch13 were associated with a significant increase of PfHRP2 plasma levels.\n\nConclusionsThis study provides the baseline prevalence of kelch13 polymorphisms in asymptomatic infection for molecular surveillance in tracking AR, and suggests the need for additional studies to explore the association of kelch13 polymorphisms with P. falciparum burden independent of AR, in this region of Cameroon.

microbiology↗