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1.
Mol Biol Evol ; 41(7)2024 Jul 03.
Article in English | MEDLINE | ID: mdl-38985692

ABSTRACT

The primary control methods for the African malaria mosquito, Anopheles gambiae, are based on insecticidal interventions. Emerging resistance to these compounds is therefore of major concern to malaria control programs. The organophosphate (OP), pirimiphos-methyl, is a relatively new chemical in the vector control armory but is now widely used in indoor-residual spray campaigns. While generally effective, phenotypic resistance has developed in some areas in malaria vectors. Here, we used a population genomic approach to identify novel mechanisms of resistance to pirimiphos-methyl in A. gambiae s.l mosquitoes. In multiple populations, we found large and repeated signals of selection at a locus containing a cluster of detoxification enzymes, some of whose orthologs are known to confer resistance to OPs in Culex pipiens. Close examination revealed a pair of alpha-esterases, Coeae1f and Coeae2f, and a complex and diverse pattern of haplotypes under selection in A. gambiae, A. coluzzii and A. arabiensis. As in C. pipiens, copy number variants have arisen at this locus. We used diplotype clustering to examine whether these signals arise from parallel evolution or adaptive introgression. Using whole-genome sequenced phenotyped samples, we found that in West Africa, a copy number variant in A. gambiae is associated with resistance to pirimiphos-methyl. Overall, we demonstrate a striking example of contemporary parallel evolution which has important implications for malaria control programs.


Subject(s)
Anopheles , Esterases , Insecticide Resistance , Insecticides , Mosquito Vectors , Organothiophosphorus Compounds , Animals , Anopheles/genetics , Insecticide Resistance/genetics , Mosquito Vectors/genetics , Insecticides/pharmacology , Esterases/genetics , Evolution, Molecular
2.
Proc Biol Sci ; 291(2031): 20241142, 2024 Sep.
Article in English | MEDLINE | ID: mdl-39288798

ABSTRACT

Malaria control relies on insecticides targeting the mosquito vector, but this is increasingly compromised by insecticide resistance, which can be achieved by elevated expression of detoxifying enzymes that metabolize the insecticide. In diploid organisms, gene expression is regulated both in cis, by regulatory sequences on the same chromosome, and by trans acting factors, affecting both alleles equally. Differing levels of transcription can be caused by mutations in cis-regulatory modules (CRM), but few of these have been identified in mosquitoes. We crossed bendiocarb-resistant and susceptible Anopheles gambiae strains to identify cis-regulated genes that might be responsible for the resistant phenotype using RNAseq, and CRM sequences controlling gene expression in insecticide resistance relevant tissues were predicted using machine learning. We found 115 genes showing allele-specific expression (ASE) in hybrids of insecticide susceptible and resistant strains, suggesting cis-regulation is an important mechanism of gene expression regulation in A. gambiae. The genes showing ASE included a higher proportion of Anopheles-specific genes on average younger than genes with balanced allelic expression.


Subject(s)
Alleles , Anopheles , Gene Expression Regulation , Insecticide Resistance , Anopheles/genetics , Anopheles/metabolism , Animals , Insecticide Resistance/genetics , Mosquito Vectors/genetics , Mosquito Vectors/metabolism , Insecticides/pharmacology
3.
Mol Ecol ; : e17542, 2024 Oct 07.
Article in English | MEDLINE | ID: mdl-39374937

ABSTRACT

A major insecticide resistance mechanism in insect pests is knock-down resistance (kdr) caused by mutations in the voltage-gated sodium channel (Vgsc) gene. Despite being common in most malaria Anopheles vector species, kdr mutations have never been observed in Anopheles funestus, the principal malaria vector in Eastern and Southern Africa, with resistance mainly being conferred by detoxification enzymes. In a parallel study, we monitored 10 populations of An. funestus in Tanzania for insecticide resistance unexpectedly identified resistance to a banned insecticide, DDT, in the Morogoro region. Through whole-genome sequencing of 333 An. funestus samples from these populations, we found eight novel amino acid substitutions in the Vgsc gene, including the kdr variant, L976F (equivalent to L995F in An. gambiae), in tight linkage disequilibrium with another (P1842S). The mutants were found only at high frequency in one region and were accompanied by weak signatures of a selective sweep, with a significant decline between 2017 and 2023. Notably, kdr L976F was strongly associated with survivorship to exposure to DDT insecticide, while no clear association was noted with a pyrethroid insecticide (deltamethrin). The WHO prequalifies no DDT products for vector control, and the chemical is banned in Tanzania. Widespread DDT contamination and a legacy of extensive countrywide stockpiles may have selected for this mutation. Continued monitoring is necessary to understand the origin of kdr in An. funestus, and the threat posed to insecticide-based vector control in Africa.

4.
Phys Rev Lett ; 133(12): 121001, 2024 Sep 20.
Article in English | MEDLINE | ID: mdl-39373453

ABSTRACT

Recent measurements of the four-point correlation function in large-scale galaxy surveys have found apparent evidence of parity violation in the distribution of galaxies. This cannot happen via dynamical gravitational effects in general relativity. If such a violation arose from physics in the early Universe it could indicate important new physics beyond the standard model, and would be at odds with most models of inflation. It is therefore now timely to consider the galaxy trispectrum in more detail. While the intrinsic four-point correlation function, or equivalently the trispectrum, its Fourier counterpart, is parity invariant, the observed trispectrum must take redshift-space distortions into account. Although the standard Newtonian correction also respects parity invariance, we show that subleading relativistic corrections do not. We demonstrate that these can be significant at intermediate linear scales and are dominant over the Newtonian parity-invariant part around the equality scale and above. Therefore when observing the galaxy four-point correlation function, we should expect to detect parity violation on large scales.

5.
Mov Disord ; 39(3): 486-497, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38197134

ABSTRACT

BACKGROUND: Spinocerebellar ataxia type 4 (SCA4) is an autosomal dominant ataxia with invariable sensory neuropathy originally described in a family with Swedish ancestry residing in Utah more than 25 years ago. Despite tight linkage to the 16q22 region, the molecular diagnosis has since remained elusive. OBJECTIVES: Inspired by pathogenic structural variation implicated in other 16q-ataxias with linkage to the same locus, we revisited the index SCA4 cases from the Utah family using novel technologies to investigate structural variation within the candidate region. METHODS: We adopted a targeted long-read sequencing approach with adaptive sampling on the Oxford Nanopore Technologies (ONT) platform that enables the detection of segregating structural variants within a genomic region without a priori assumptions about any variant features. RESULTS: Using this approach, we found a heterozygous (GGC)n repeat expansion in the last coding exon of the zinc finger homeobox 3 (ZFHX3) gene that segregates with disease, ranging between 48 and 57 GGC repeats in affected probands. This finding was replicated in a separate family with SCA4. Furthermore, the estimation of this GGC repeat size in short-read whole genome sequencing (WGS) data of 21,836 individuals recruited to the 100,000 Genomes Project in the UK and our in-house dataset of 11,258 exomes did not reveal any pathogenic repeats, indicating that the variant is ultrarare. CONCLUSIONS: These findings support the utility of adaptive long-read sequencing as a powerful tool to decipher causative structural variation in unsolved cases of inherited neurological disease. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.


Subject(s)
Cerebellar Ataxia , Spinocerebellar Ataxias , Humans , Pedigree , Spinocerebellar Ataxias/genetics , Cerebellar Ataxia/genetics , Exons , Homeodomain Proteins/genetics
6.
Malar J ; 23(1): 280, 2024 Sep 17.
Article in English | MEDLINE | ID: mdl-39285410

ABSTRACT

BACKGROUND: Intensive deployment of insecticide based malaria vector control tools resulted in the rapid evolution of phenotypes resistant to these chemicals. Understanding this process at the genomic level is important for the deployment of successful vector control interventions. Therefore, longitudinal sampling followed by whole genome sequencing (WGS) is necessary to understand how these evolutionary processes evolve over time. This study investigated the change in genetic structure and the evolution of the insecticide resistance variants in natural populations of Anopheles gambiae over time and space from 2012 to 2017 in Burkina Faso. METHODS: New genomic data have been generated from An. gambiae mosquitoes collected from three villages in the western part of Burkina Faso between 2012 and 2017. The samples were whole-genome sequenced and the data used in the An. gambiae 1000 genomes (Ag1000G) project as part of the Vector Observatory. Genomic data were analysed using the analysis pipeline previously designed by the Ag1000G project. RESULTS: The results showed similar and consistent nucleotide diversity and negative Tajima's D between An. gambiae sensu stricto (s.s.) and Anopheles coluzzii. Principal component analysis (PCA) and the fixation index (FST) showed a clear genetic structure in the An. gambiae sensu lato (s.l.) species. Genome-wide FST and H12 scans identified genomic regions under divergent selection that may have implications in the adaptation to ecological changes. Novel voltage-gated sodium channel pyrethroid resistance target-site alleles (V402L, I1527T) were identified at increasing frequencies alongside the established alleles (Vgsc-L995F, Vgsc-L995S and N1570Y) within the An. gambiae s.l. POPULATIONS: Organophosphate metabolic resistance markers were also identified, at increasing frequencies, within the An. gambiae s.s. populations from 2012 to 2017, including the SNP Ace1-G280S and its associated duplication. Variants simultaneously identified in the same vector populations raise concerns about the long-term efficacy of new generation bed nets and the recently organophosphate pirimiphos-methyl indoor residual spraying in Burkina Faso. CONCLUSION: These findings highlighted the benefit of genomic surveillance of malaria vectors for the detection of new insecticide resistance variants, the monitoring of the existing resistance variants, and also to get insights into the evolutionary processes driving insecticide resistance.


Subject(s)
Anopheles , Insecticide Resistance , Mosquito Vectors , Whole Genome Sequencing , Insecticide Resistance/genetics , Anopheles/genetics , Anopheles/drug effects , Animals , Burkina Faso , Mosquito Vectors/genetics , Mosquito Vectors/drug effects , Longitudinal Studies , Evolution, Molecular , Insecticides/pharmacology , Malaria/transmission
7.
Nature ; 547(7663): 306-310, 2017 07 19.
Article in English | MEDLINE | ID: mdl-28726833

ABSTRACT

The time of arrival of people in Australia is an unresolved question. It is relevant to debates about when modern humans first dispersed out of Africa and when their descendants incorporated genetic material from Neanderthals, Denisovans and possibly other hominins. Humans have also been implicated in the extinction of Australia's megafauna. Here we report the results of new excavations conducted at Madjedbebe, a rock shelter in northern Australia. Artefacts in primary depositional context are concentrated in three dense bands, with the stratigraphic integrity of the deposit demonstrated by artefact refits and by optical dating and other analyses of the sediments. Human occupation began around 65,000 years ago, with a distinctive stone tool assemblage including grinding stones, ground ochres, reflective additives and ground-edge hatchet heads. This evidence sets a new minimum age for the arrival of humans in Australia, the dispersal of modern humans out of Africa, and the subsequent interactions of modern humans with Neanderthals and Denisovans.


Subject(s)
Human Migration/history , Africa/ethnology , Animals , Australia , Diet/history , Fossils , Geologic Sediments/analysis , History, Ancient , Humans , Neanderthals
8.
Genome Res ; 29(8): 1250-1261, 2019 08.
Article in English | MEDLINE | ID: mdl-31345938

ABSTRACT

Polymorphisms in genetic copy number can influence gene expression, coding sequence, and zygosity, making them powerful actors in the evolutionary process. Copy number variants (CNVs) are however understudied, being more difficult to detect than single-nucleotide polymorphisms. We take advantage of the intense selective pressures on the major malaria vector Anopheles gambiae, caused by the widespread use of insecticides for malaria control, to investigate the role of CNVs in the evolution of insecticide resistance. Using the whole-genome sequencing data from 1142 samples in the An. gambiae 1000 genomes project, we identified 250 gene-containing CNVs, encompassing a total of 267 genes of which 28 were in gene families linked to metabolic insecticide resistance, representing significant enrichment of these families. The five major gene clusters for metabolic resistance all contained CNVs, with 44 different CNVs being found across these clusters and multiple CNVs frequently covering the same genes. These 44 CNVs are widespread (45% of individuals carry at least one of them) and have been spreading through positive selection, indicated by their high local frequencies and extended haplotype homozygosity. Our results demonstrate the importance of CNVs in the response to selection, highlighting the urgent need to identify the contribution of each CNV to insecticide resistance and to track their spread as the use of insecticides in malaria endemic countries intensifies and as the operational deployment of next-generation bed nets targeting metabolic resistance gathers pace. Our detailed descriptions of CNVs found across the species range provide the tools to do so.


Subject(s)
Anopheles/genetics , Cytochrome P-450 Enzyme System/genetics , DNA Copy Number Variations , Genome, Insect , Insecticide Resistance/genetics , Mosquito Vectors/genetics , Animals , Anopheles/parasitology , Biological Evolution , Chromosome Mapping , Cytochrome P-450 Enzyme System/metabolism , Gene Dosage , Genetic Loci , Haplotypes , Homozygote , Humans , Insect Proteins/genetics , Insect Proteins/metabolism , Insecticides , Malaria/prevention & control , Malaria/transmission , Mosquito Vectors/parasitology , Multigene Family , Pyrethrins , Selection, Genetic , Whole Genome Sequencing
9.
Mol Ecol ; 30(21): 5303-5317, 2021 11.
Article in English | MEDLINE | ID: mdl-33590926

ABSTRACT

Resistance to pyrethroid insecticides is a major concern for malaria vector control. Pyrethroids target the voltage-gated sodium channel (VGSC), an essential component of the mosquito nervous system. Substitutions in the amino acid sequence can induce a resistance phenotype. We use whole-genome sequence data from phase 2 of the Anopheles gambiae 1000 Genomes Project (Ag1000G) to provide a comprehensive account of genetic variation in the Vgsc gene across 13 African countries. In addition to known resistance alleles, we describe 20 other non-synonymous nucleotide substitutions at appreciable population frequency and map these variants onto a protein model to investigate the likelihood of pyrethroid resistance phenotypes. Thirteen of these novel alleles were found to occur almost exclusively on haplotypes carrying the known L995F kdr (knock-down resistance) allele and may enhance or compensate for the L995F resistance genotype. A novel mutation I1527T, adjacent to a predicted pyrethroid-binding site, was found in tight linkage with V402L substitutions, similar to allele combinations associated with resistance in other insect species. We also analysed genetic backgrounds carrying resistance alleles, to determine which alleles have experienced recent positive selection, and describe ten distinct haplotype groups carrying known kdr alleles. Five of these groups are observed in more than one country, in one case separated by over 3000 km, providing new information about the potential for the geographical spread of resistance. Our results demonstrate that the molecular basis of target-site pyrethroid resistance in malaria vectors is more complex than previously appreciated, and provide a foundation for the development of new genetic tools for insecticide resistance management.


Subject(s)
Anopheles , Insecticides , Malaria , Pyrethrins , Animals , Anopheles/genetics , Insecticides/pharmacology , Malaria/genetics , Mosquito Vectors/genetics , Pyrethrins/pharmacology
10.
J Hum Genet ; 65(10): 875-887, 2020 Oct.
Article in English | MEDLINE | ID: mdl-32483274

ABSTRACT

New Guineans represent one of the oldest locally continuous populations outside Africa, harboring among the greatest linguistic and genetic diversity on the planet. Archeological and genetic evidence suggest that their ancestors reached Sahul (present day New Guinea and Australia) by at least 55,000 years ago (kya). However, little is known about this early settlement phase or subsequent dispersal and population structuring over the subsequent period of time. Here we report 379 complete Papuan mitochondrial genomes from across Papua New Guinea, which allow us to reconstruct the phylogenetic and phylogeographic history of northern Sahul. Our results support the arrival of two groups of settlers in Sahul within the same broad time window (50-65 kya), each carrying a different set of maternal lineages and settling Northern and Southern Sahul separately. Strong geographic structure in northern Sahul remains visible today, indicating limited dispersal over time despite major climatic, cultural, and historical changes. However, following a period of isolation lasting nearly 20 ky after initial settlement, environmental changes postdating the Last Glacial Maximum stimulated diversification of mtDNA lineages and greater interactions within and beyond Northern Sahul, to Southern Sahul, Wallacea and beyond. Later, in the Holocene, populations from New Guinea, in contrast to those of Australia, participated in early interactions with incoming Asian populations from Island Southeast Asia and continuing into Oceania.


Subject(s)
Ethnicity/genetics , Human Migration/history , Adult , Asia, Southeastern , Australia , Ethnicity/history , Female , Genome, Mitochondrial , Geological Phenomena , Haplotypes/genetics , History, Ancient , Humans , Likelihood Functions , Male , New Guinea , Papua New Guinea , Phylogeny , Phylogeography , Tasmania
11.
Nat Rev Genet ; 15(3): 176-92, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24535286

ABSTRACT

Speciation is a fundamental evolutionary process, the knowledge of which is crucial for understanding the origins of biodiversity. Genomic approaches are an increasingly important aspect of this research field. We review current understanding of genome-wide effects of accumulating reproductive isolation and of genomic properties that influence the process of speciation. Building on this work, we identify emergent trends and gaps in our understanding, propose new approaches to more fully integrate genomics into speciation research, translate speciation theory into hypotheses that are testable using genomic tools and provide an integrative definition of the field of speciation genomics.


Subject(s)
Genomics , Biodiversity , Models, Genetic
12.
J Microsc ; 265(1): 60-72, 2017 01.
Article in English | MEDLINE | ID: mdl-27596097

ABSTRACT

Samples of Late Devonian/Early Mississippian New Albany Shale from the Illinois Basin, having maturities ranging from early mature to postmature, were analysed using micro-Fourier transform infrared (FTIR) spectroscopy, ImageJ processing software and scanning electron microscopic X-ray spectroscopy to explore the distribution, connectivity and chemical composition of organic matter, clay minerals, carbonate minerals and quartz, and to further test the applicability of micro-FTIR mapping to study shale heterogeneity. Each sample was analysed in planes parallel and perpendicular to the bedding to investigate anisotropy in component distribution, with a possible implication for better understanding anisotropy in porosity and permeability in organic-matter-rich shales. Our results show that for low-maturity samples, organic matter is better connected in the plane parallel to the bedding than in the plane perpendicular to the bedding. Organic matter connectivity decreases with increasing maturity as a result of kerogen transformation. Clay minerals are very well connected in both planes, whereas carbonate minerals are not abundant whilst dominantly isolated in most samples, independent of maturity. This study demonstrates that micro-FTIR mapping is a valuable tool for studying shale heterogeneity on a micrometre to millimetre scale that becomes even more powerful in combination with scanning electron microscopy techniques, which extend observations to a nanometre scale. However, to obtain meaningful and comparable results, micro-FTIR mapping requires very careful standardization, precise selection of peak heights/areas and mapping conditions (such as aperture size, scan numbers, resolution, etc.) well suited for the analysed samples.

13.
J Hum Evol ; 101: 45-64, 2016 12.
Article in English | MEDLINE | ID: mdl-27886810

ABSTRACT

Jerimalai is a rock shelter in East Timor with cultural remains dated to 42,000 years ago, making it one of the oldest known sites of modern human activity in island Southeast Asia. It has special global significance for its record of early pelagic fishing and ancient shell fish hooks. It is also of regional significance for its early occupation and comparatively large assemblage of Pleistocene stone artefacts. Three major findings arise from our study of the stone artefacts. First, there is little change in lithic technology over the 42,000 year sequence, with the most noticeable change being the addition of new artefact types and raw materials in the mid-Holocene. Second, the assemblage is dominated by small chert cores and implements rather than pebble tools and choppers, a pattern we argue pattern, we argue, that is common in island SE Asian sites as opposed to mainland SE Asian sites. Third, the Jerimalai assemblage bears a striking resemblance to the assemblage from Liang Bua, argued by the Liang Bua excavation team to be associated with Homo floresiensis. We argue that the near proximity of these two islands along the Indonesian island chain (c.100 km apart), the long antiquity of modern human occupation in the region (as documented at Jerimalai), and the strong resemblance of distinctive flake stone technologies seen at both sites, raises the intriguing possibility that both the Liang Bua and Jerimalai assemblages were created by modern humans.


Subject(s)
Biological Evolution , Fossils , Hominidae , Technology , Animals , Archaeology , Fishes , Humans , Timor-Leste
14.
Phys Rev Lett ; 114(5): 051302, 2015 Feb 06.
Article in English | MEDLINE | ID: mdl-25699430

ABSTRACT

The large-scale homogeneity and isotropy of the Universe is generally thought to imply a well-defined background cosmological model. It may not. Smoothing over structure adds in an extra contribution, transferring power from small scales up to large. Second-order perturbation theory implies that the effect is small, but suggests that formally the perturbation series may not converge. The amplitude of the effect is actually determined by the ratio of the Hubble scales at matter-radiation equality and today-which are entirely unrelated. This implies that a universe with significantly lower temperature today could have significant backreaction from more power on small scales, and so provides the ideal testing ground for understanding backreaction. We investigate this using two different N-body numerical simulations-a 3D Newtonian and a 1D simulation which includes all relevant relativistic effects. We show that while perturbation theory predicts an increasing backreaction as more initial small-scale power is added, in fact the virialization of structure saturates the backreaction effect at the same level independently of the equality scale. This implies that backreaction is a small effect independently of initial conditions. Nevertheless, it may still contribute at the percent level to certain cosmological observables and therefore it cannot be neglected in precision cosmology.

15.
J Hum Evol ; 83: 46-64, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25957653

ABSTRACT

Published ages of >50 ka for occupation at Madjedbebe (Malakunanja II) in Australia's north have kept the site prominent in discussions about the colonisation of Sahul. The site also contains one of the largest stone artefact assemblages in Sahul for this early period. However, the stone artefacts and other important archaeological components of the site have never been described in detail, leading to persistent doubts about its stratigraphic integrity. We report on our analysis of the stone artefacts and faunal and other materials recovered during the 1989 excavations, as well as the stratigraphy and depositional history recorded by the original excavators. We demonstrate that the technology and raw materials of the early assemblage are distinctive from those in the overlying layers. Silcrete and quartzite artefacts are common in the early assemblage, which also includes edge-ground axe fragments and ground haematite. The lower flaked stone assemblage is distinctive, comprising a mix of long convergent flakes, some radial flakes with faceted platforms, and many small thin silcrete flakes that we interpret as thinning flakes. Residue and use-wear analysis indicate occasional grinding of haematite and woodworking, as well as frequent abrading of platform edges on thinning flakes. We conclude that previous claims of extensive displacement of artefacts and post-depositional disturbance may have been overstated. The stone artefacts and stratigraphic details support previous claims for human occupation 50-60 ka and show that human occupation during this time differed from later periods. We discuss the implications of these new data for understanding the first human colonisation of Sahul.


Subject(s)
Archaeology/methods , Occupations/history , Artifacts , Australia , History, Ancient , Humans , Technology/history
16.
Genome Biol Evol ; 16(9)2024 Sep 03.
Article in English | MEDLINE | ID: mdl-39226386

ABSTRACT

Mitochondrial DNA has been a popular marker in phylogeography, phylogeny, and molecular ecology, but its complex evolution is increasingly recognized. Here, we investigated mitochondrial DNA variation in Anopheles gambiae and Anopheles coluzzii, in relation to other species in the Anopheles gambiae complex, by assembling the mitogenomes of 1,219 mosquitoes across Africa. The mitochondrial DNA phylogeny of the Anopheles gambiae complex was consistent with previously reported highly reticulated evolutionary history, revealing important discordances with the species tree. The three most widespread species (An. gambiae, An. coluzzii, and Anopheles arabiensis), known for extensive historical introgression, could not be discriminated based on mitogenomes. Furthermore, a monophyletic clustering of the three saltwater-tolerant species (Anopheles merus, Anopheles melas, and Anopheles bwambae) in the Anopheles gambiae complex also suggested that introgression and possibly selection shaped mitochondrial DNA evolution. Mitochondrial DNA variation in An. gambiae and An. coluzzii across Africa revealed significant partitioning among populations and species. A peculiar mitochondrial DNA lineage found predominantly in An. coluzzii and in the hybrid taxon of the African "far-west" exhibited divergence comparable to the interspecies divergence in the Anopheles gambiae complex, with a geographic distribution matching closely An. coluzzii's geographic range. This phylogeographic relict of the An. coluzzii and An. gambiae split was associated with population and species structure, but not with the rare Wolbachia occurrence. The lineage was significantly associated with single nucleotide polymorphisms in the nuclear genome, particularly in genes associated with pathogen and insecticide resistance. These findings underline potential mitonuclear coevolution history and the role played by mitochondria in shaping metabolic responses to pathogens and insecticides in Anopheles.


Subject(s)
Anopheles , DNA, Mitochondrial , Insecticide Resistance , Phylogeny , Phylogeography , Animals , Anopheles/genetics , DNA, Mitochondrial/genetics , Insecticide Resistance/genetics , Genome, Mitochondrial , Evolution, Molecular , Genetic Variation , Insecticides/pharmacology , Mitochondria/genetics , Africa
17.
Commun Biol ; 7(1): 1115, 2024 Sep 10.
Article in English | MEDLINE | ID: mdl-39256556

ABSTRACT

The two main Afrotropical malaria vectors - Anopheles coluzzii and An. gambiae - are genetically distinct and reproductively isolated across West Africa. However, populations at the western extreme of their range are assigned as "intermediate" between the two species by whole genome sequence (WGS) data, and as hybrid forms by conventional molecular diagnostics. By exploiting WGS data from 1190 specimens collected across west Africa via the Anopheles gambiae 1000 Genomes network, we identified a putative taxon in the far-west (provisionally named Bissau molecular form), which did not arise by admixture but rather may have originated at the same time as the split between An. coluzzii and An. gambiae. Intriguingly, this taxon lacks insecticide resistance mechanisms commonly observed in the two main species. These findings lead to a change of perspective on malaria vector species in the far-west region with potential for epidemiological implications, and a new challenge for genetic-based mosquito control approaches.


Subject(s)
Anopheles , Mosquito Vectors , Anopheles/genetics , Anopheles/classification , Animals , Mosquito Vectors/genetics , Mosquito Vectors/classification , Africa, Western , Insecticide Resistance/genetics , Malaria/transmission , Genome, Insect , Whole Genome Sequencing , Phylogeny
18.
Sci Rep ; 14(1): 21782, 2024 09 18.
Article in English | MEDLINE | ID: mdl-39294180

ABSTRACT

The Democratic Republic of Congo (DRC) suffers from one of the highest malaria burdens worldwide, but information on its Anopheles vector populations is relatively limited. Preventative malaria control in DRC is reliant on pyrethroid-treated nets, raising concerns over the potential impacts of insecticide resistance. We sampled Anopheles gambiae from three geographically distinct populations (Kimpese, Kapolowe and Mikalayi) in southern DRC, collecting from three sub-sites per population and characterising mosquito collections from each for resistance to pyrethroids using WHO tube bioassays. Resistance to each of three different pyrethroids was generally high in An. gambiae with < 92% mortality in all tests, but varied between collections, with mosquitoes from Kimpese being the most resistant. Whole genome sequencing of 165 An. gambiae revealed evidence for genetic differentiation between Kimpese and Kapolowe/Mikalayi, but not between the latter two sample sites despite separation of approximately 800 km. Surprisingly, there was evidence of population structure at a small spatial scale between collection subsites in Kimpese, despite separation of just tens of kilometres. Intra-population (H12) and inter-population (FST) genome scans identified multiple peaks corresponding to genes associated with insecticide resistance such as the voltage gated sodium channel (Vgsc) target site on chromosome 2L, a Cyp6 cytochrome P450 cluster on chromosome arm 2R, and the Cyp9k1 P450 gene on chromosome X. In addition, in the Kimpese subsites, the P450 redox partner gene Cpr showed evidence for contemporary selection (H12) and population differentiation (FST) meriting further exploration as a potential resistance associated marker.


Subject(s)
Anopheles , Insecticide Resistance , Insecticides , Mosquito Vectors , Pyrethrins , Animals , Anopheles/genetics , Anopheles/drug effects , Insecticide Resistance/genetics , Democratic Republic of the Congo , Pyrethrins/pharmacology , Insecticides/pharmacology , Mosquito Vectors/genetics , Mosquito Vectors/drug effects , Malaria/transmission
19.
bioRxiv ; 2024 Feb 01.
Article in English | MEDLINE | ID: mdl-38352547

ABSTRACT

The primary control methods for the African malaria mosquito, Anopheles gambiae, are based on insecticidal interventions. Emerging resistance to these compounds is therefore of major concern to malaria control programmes. The organophosphate, pirimiphos-methyl, is a relatively new chemical in the vector control armoury but is now widely used in indoor residual spray campaigns. Whilst generally effective, phenotypic resistance has developed in some areas in malaria vectors. Here, we used a population genomic approach to identify novel mechanisms of resistance to pirimiphos-methyl in Anopheles gambiae s.l mosquitoes. In multiple populations, we found large and repeated signals of selection at a locus containing a cluster of detoxification enzymes, some of whose orthologs are known to confer resistance to organophosphates in Culex pipiens. Close examination revealed a pair of alpha-esterases, Coeae1f and Coeae2f, and a complex and diverse pattern of haplotypes under selection in An. gambiae, An. coluzzii and An. arabiensis. As in Cx. pipiens, copy number variation seems to play a role in the evolution of insecticide resistance at this locus. We used diplotype clustering to examine whether these signals arise from parallel evolution or adaptive introgression. Using whole-genome sequenced phenotyped samples, we found that in West Africa, a copy number variant in Anopheles gambiae is associated with resistance to pirimiphos-methyl. Overall, we demonstrate a striking example of contemporary parallel evolution which has important implications for malaria control programmes.

20.
Sci Rep ; 14(1): 2579, 2024 01 31.
Article in English | MEDLINE | ID: mdl-38296988

ABSTRACT

Secure archaeological evidence for human occupation on the eastern seaboard of Australia before ~ 25,000 years ago has proven elusive. This has prompted some researchers to argue that the coastal margins remained uninhabited prior to 25 ka. Here we show evidence for human occupation beginning between 30 ± 6 and 49 ± 8 ka at Wallen Wallen Creek (WWC), and at Middle Canalpin Creek (MCA20) between 38 ± 8 and 41 ± 8 ka. Both sites are located on the western side of Minjerribah (North Stradbroke Island), the second largest sand island in the world, isolated by rising sea levels in the early Holocene. The earliest occupation phase at both sites consists of charcoal and heavily retouched stone artefacts made from exotic raw materials. Heat-treatment of imported silcrete artefacts first appeared in sediment dated to ~ 30,000 years ago, making these amongst Australia's oldest dated heat-treated artefacts. An early human presence on Minjerribah is further suggested by palaeoenvironmental records of anthropogenic burning beginning by 45,000 years ago. These new chronologies from sites on a remnant portion of the continental margin confirm early human occupation along Sahul's now-drowned eastern continental shelf.


Subject(s)
Occupations , Sea Level Rise , Humans , Australia , Archaeology , Sand , Fossils
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