Modeling the spatio-temporal distribution of M and S molecular forms of Anopheles gambiae and Anopheles funestus in south Benin

Species and ecotypes of malaria vectors adopt different strategies to avoid vector control intervention based on residual insecticides. Mapping their distributions would be useful to improve vector control and to reach objectives of malaria elimination. Here, we analyzed the spatio-temporal distribution of An. funestus (AF) and both M and S molecular forms of An. gambiae s.s. (AGM and AGS) that are sympatric in south Benin. Presence-absence data of AGM, AGS and AF from 1-year human-landing collections in 28 villages were assessed using binomial mixed-effects (BME) models with a set of environmental covariates. Temperatures, rainfall and NDVI were derived from satellite images. Landscape metrics based on an object-oriented classification of land-use were computed in a buffer area around each village. A breeding sites inventory was performed in the perimeter of each village. The vector control interventions implemented in the villages were also introduced in the models. After 8-fold cross-validations of the models, predictive maps of presence of AGM, AGS and AF were computed. BME models showed that presence of AGM and AGS were positively associated with the presence of domestic breeding sites positive for Anopheles larvae, market gardening, hydromorphic soils and the cumulated rainfall during the 15 days preceding the caught. Nocturnal temperatures were positively correlated with the presence of AGS and negatively with AGM. The opposite was found with NDVI. Presence of AF was highly correlated with the land-cover evenness, nocturnal temperatures, cumulated rainfalls and the presence of surface freshwater. Model validations showed the AF, AGM and AGS models provided respectively an excellent (AUC>0.9), a good (AUC>0.8) and an acceptable (AUC>0.7) level of prediction. These results showed that available remote sensing data could help to predict the presence of several species of malaria vectors at a village level. These models could be used to map species-dependant parameters like biting behaviour or mechanisms of resistance to vector control. (Texte intégral

Changes in Anopheles funestus biting behaviour following universal coverage of long-lasting insecticidal nets in Benin

Behavioural modification of malaria vectors in response to vector control methods is of great concern. We investigated whether full coverage of Long-Lasting Insecticide-treated mosquito Nets (LLIN) may induce a switch in biting behaviour in Anopheles funestus, a major malaria vector in Africa. Human-landing collections were conducted indoor and outdoor in two villages (Lokohouè and Tokoli) in Benin prior, 1 year and 3 years after implementation of universal LLIN coverage. Proportion of Outdoor Biting (POB) and Median Catching Times (MCT) were compared. The resistance of An. funestus to deltamethrin was monitored using bioassays. MCT of An. funestus switched from 02:00 in Lokohoué and 03:00 in Tokoli to 05:00 after 3 years (Mann- Whitney p-value<0.0001). In Tokoli, POB increased from 45% to 68.1% (OR=2.55; 95CI=1.72- 3.78;p<0.0001) 1 year after the universal coverage whereas POB was unchanged in Lokohoué. In Lokohoué, however, the proportion of An. funestus that bites after 06:00 was 26%. Bioassays showed no resistance to deltamethrin. This study provides evidence for a switch in malaria vectors biting behaviour following the implementation of LLIN at universal coverage. These findings might have direct consequences for malaria control in Africa and highlighted the need for alternative strategies for better targeting malaria vectors. (Texte intégral

Modelling the risk of being bitten by malaria vectors in a vector control area in southern Benin, west Africa

Background: The diversity of malaria vector populations, expressing various resistance and/or behavioural patterns could explain the reduced effectiveness of vector control interventions reported in some African countries. A better understanding of the ecology and distribution of malaria vectors is essential to design more effective and sustainable strategies for malaria control and elimination. Here, we analyzed the spatio-temporal risk of the contact between humans and the sympatric An. funestus and both M and S molecular forms of An. gambiae s.s. in an area of Benin with high coverage of vector control measures with an unprecedented level of resolution. Methods: Presence-absence data for the three vectors from 1-year human-landing collections in 19 villages were assessed using binomial mixed-effects models according to vector control measures and environmental covariates derived from field and remote sensing data. After 8-fold cross-validations of the models, predictive maps of the risk of the contact between humans and the sympatric An. funestus and both molecular M and S forms of An. gambiae s.s. were computed. Results: Model validations showed that the An. funestus, An. gambiae M form, and S form models provided an excellent (Area Under Curve>0.9), a good (AUC>0.8), and an acceptable (AUC>0.7) level of prediction, respectively. The distribution area of the probability of contact between human and An. funestus largely overlaps that of An. gambiae M form but this latter showed important seasonal variation. An. gambiae S form also showed seasonal variation but with different ecological preferences. Landscape data were useful to discriminate between the species' distributions. Conclusions: These results showed that available remote sensing data could help in predicting the human-vector contact for several species of malaria vectors at a village level scale. The predictive maps showed seasonal and spatial variations in the risk of human-vector contact for all three vectors. Such maps could help Malaria Control Programmes to implement more effective vector control strategy by taking into account to the dynamics of malaria vector species. (Résumé d'auteur

Signal enhanced proteomics:a biological perspective on dissecting the functional organisation of cell proteomes

Proteomes are highly dynamic and can respond rapidly to environmental and cellular signals. Within cells, proteins often form distinct pools with different functions and properties. However, in quantitative proteomics studies it is common to measure averaged values for proteins that do not reflect variations that may occur between different protein isoforms, different subcellular compartments, or in cells at different cell cycle stages and so on. Here we review experimental approaches that can be used to enhance the signal from specific pools of protein that may otherwise be obscured through averaging across protein populations. This signal enhancement can help to reveal functions associated with specific protein pools, providing insight into the regulation of cellular processes. We review different strategies for proteomic signal enhancement, with a focus on the analysis of protein pools in different subcellular locations. We describe how MS-based proteome analyses can be combined with a general physico-chemical cell fractionation procedure that can be applied to many cultured cell lines.</p

Contribution of Aeromagnetic Data to the Structural Discontinuities Identification of Black Volta Catch-ment Aquifer System in Côte d'Ivoire

This study aims to improve the structural knowledge of the fissured aquifers of the Black Volta catchment in Côte d'Ivoire based on the mapping of magnetic lineaments that represent magnetic discontinuities such as magmatic body contacts or tectonic faults. Four filtering methods: pole reduction (equator), gradient (vertical and hori-zontal), upward extension, and angle tilt were applied to the residual magnetic field map to extract magnetic discontinuities using the Oasis Montaj (Geosoft) program. Euler deconvolution coupled with the analytical signal provided, in addition to the horizontal location of the magnetic contacts, an indication of their depths. The re-sulting structural map contains 458 structures with lengths ranging from 9.03 to 66.54 km. Three directions: NW-SE, E-W and NE-SW were detected, with a predomi-nance of the NW-SE direction. Depths estimated by Euler solutions range from 6.8 to 2847 m. This map is consistent with many faults already recognised or assumed by traditional structural studies and tectonic events affecting the Ivorian basement. These results contribute significantly to the improvement of the structural map of the Black Volta Basin in Côte d'Ivoire. In addition to the major known tectonic faults, numerous lineaments, particularly those at depth, have been highlighted by the pre-sent study.&nbsp; &nbsp

Contribution of Aeromagnetic Data to the Structural Discontinuities Identification of Black Volta Catch-ment Aquifer System in Côte d'Ivoire

This study aims to improve the structural knowledge of the fissured aquifers of the Black Volta catchment in Côte d'Ivoire based on the mapping of magnetic lineaments that represent magnetic discontinuities such as magmatic body contacts or tectonic faults. Four filtering methods: pole reduction (equator), gradient (vertical and hori-zontal), upward extension, and angle tilt were applied to the residual magnetic field map to extract magnetic discontinuities using the Oasis Montaj (Geosoft) program. Euler deconvolution coupled with the analytical signal provided, in addition to the horizontal location of the magnetic contacts, an indication of their depths. The re-sulting structural map contains 458 structures with lengths ranging from 9.03 to 66.54 km. Three directions: NW-SE, E-W and NE-SW were detected, with a predomi-nance of the NW-SE direction. Depths estimated by Euler solutions range from 6.8 to 2847 m. This map is consistent with many faults already recognised or assumed by traditional structural studies and tectonic events affecting the Ivorian basement. These results contribute significantly to the improvement of the structural map of the Black Volta Basin in Côte d'Ivoire. In addition to the major known tectonic faults, numerous lineaments, particularly those at depth, have been highlighted by the pre-sent study.&nbsp; &nbsp

Interactome analysis of Caenorhabditis elegans synapses by TurboID-based proximity labeling

Proximity labeling provides a powerful in vivo tool to characterize the proteome of subcellular structures and the interactome of specific proteins. The nematode Caenorhabditis elegans is one of the most intensely studied organisms in biology, offering many advantages for biochemistry. Using the highly active biotin ligase TurboID, we optimize here a proximity labeling protocol for C. elegans. An advantage of TurboID is that biotin's high affinity for streptavidin means biotin-labeled proteins can be affinity-purified under harsh denaturing conditions. By combining extensive sonication with aggressive denaturation using SDS and urea, we achieved near-complete solubilization of worm proteins. We then used this protocol to characterize the proteomes of the worm gut, muscle, skin, and nervous system. Neurons are among the smallest C. elegans cells. To probe the method's sensitivity, we expressed TurboID exclusively in the two AFD neurons and showed that the protocol could identify known and previously unknown proteins expressed selectively in AFD. The active zones of synapses are composed of a protein matrix that is difficult to solubilize and purify. To test if our protocol could solubilize active zone proteins, we knocked TurboID into the endogenous elks-1 gene, which encodes a presynaptic active zone protein. We identified many known ELKS-1-interacting active zone proteins, as well as previously uncharacterized synaptic proteins. Versatile vectors and the inherent advantages of using C. elegans, including fast growth and the ability to rapidly make and functionally test knock-ins, make proximity labeling a valuable addition to the armory of this model organism

Luminescence dating applied to medieval architecture

Avranches’ keep remains constitute a witness of Anglo-Norman knowledge on castle building. Their similarity with other buildings such as Ivry-la-Bataille castle or London Tower required determining the place of Avranches keep in this group: pioneer or imitation? Therefore, samples of brick for luminescence dating were taken from the remaining little tower. Results indicate a chronology later than assumed: second part of the 12th century and first part of 13th century. These dates tend to prove that north-east tower remains would correspond to a reconstruction phase and not to the original construction.Le donjon d’Avranches représente un des rares témoins de l’architecture castrale anglo-normande. Son plan présente d’importantes resemblance avec d’autres edifices de du même contexte chrono-culturel, comme le donjon d’Ivry-la-Bataille ou la Tour de Londres. Ces ressemblances posent la question de la place du donjon d’Avranches dans cet ensemble : s’agit-il d’un édifice précurseur ou d’une imitation ? C’est pourquoi plusieurs prélèvements de brique ont été prélevés dans les vestiges de ce bâtiment, afin de procéder à la datation de la sa construction. Les résultats semblent suggérer une construction plus tardive qu’on ne l’envisageait, entre la deuxième moitié du xiie siècle et la première moitié du xiiie siècle. Ces dates pourraient suggérer une reconstruction partielle du donjon, sans correspondre à la phase de construction originale du château

Culicidae diversity, malaria transmission and insecticide resistance alleles in malaria vectors in Ouidah-Kpomasse-Tori district from Benin (West Africa): A pre-intervention study

<p>Abstract</p> <p>Background</p> <p>To implement an Insecticide Resistance Management (IRM) strategy through a randomized controlled trial (phase III), 28 villages were selected in southern Benin. No recent entomological data being available in these villages, entomological surveys were performed between October 2007 and May 2008, before vector control strategies implementation, to establish baseline data.</p> <p>Methods</p> <p>Mosquitoes were sampled by human landing collection (16 person-nights per village per survey per village) during 5 surveys. Mosquitoes were identified morphologically and by molecular methods. The <it>Plasmodium falciparum </it>circumsporozoïte indexes were measured by ELISA, and the entomological inoculation rates (EIRs) were calculated. Molecular detection of pyrethroid knock down resistance (<it>Kdr</it>) and of insensitive acetylcholinesterase were performed.</p> <p>Results</p> <p>44,693 mosquitoes belonging to 28 different species were caught from October 2007 to May 2008. Among mosquitoes caught, 318 were <it>An. gambiae s.s</it>., 2 were <it>An. nili</it>, 568 were <it>An. funestus s.s</it>., and one individual was <it>An. leesoni</it>. EIR was 2.05 ± 1.28 infective bites per human per 100 nights on average, of which 0.67 ± 0.60 were from <it>An. funestus </it>and 1.38 ± 0.94 infective bites were from <it>An. gambiae</it>. Important variations were noted between villages considering mosquito density and malaria transmission indicating a spatial heterogeneity in the study area. The <it>kdr </it>allelic frequency was 28.86% in <it>An. gambiae s.s</it>. on average and significantly increases from October 2007 (10.26%) to May 2008 (33.87%) in M molecular form of <it>An. gambiae s.s</it>. <it>Ace 1 </it>mutation was found in S molecular of <it>An. gambiae s.s </it>at a low frequency (< 1%).</p> <p>Conclusion</p> <p>This study updates information on mosquito diversity and malaria risk in rural villages from south Benin. It showed a high spatial heterogeneity in mosquito distribution and malaria transmission and underlines the need of further investigations of biological, ecological, and behavioral traits of malaria vectors species and forms. This study is a necessary prerequisite to cartography malaria risk and to improve vector control operations in southern Benin.</p