45 research outputs found

    A new species in the major malaria vector complex sheds light on reticulated species evolution

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    Complexes of closely related species provide key insights into the rapid and independent evolution of adaptive traits. Here, we described and studied Anopheles fontenillei sp.n., a new species in the Anopheles gambiae complex that we recently discovered in the forested areas of Gabon, Central Africa. Our analysis placed the new taxon in the phylogenetic tree of the An. gambiae complex, revealing important introgression events with other members of the complex. Particularly, we detected recent introgression, with Anopheles gambiae and Anopheles coluzzii, of genes directly involved in vectorial capacity. Moreover, genome analysis of the new species allowed us to clarify the evolutionary history of the 3La inversion. Overall, An. fontenillei sp.n. analysis improved our understanding of the relationship between species within the An. gambiae complex, and provided insight into the evolution of vectorial capacity traits that are relevant for the successful control of malaria in Africa

    Haemosporidian parasites of Antelopes and other vertebrates from Gabon, Central Africa

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    Re-examination, using molecular tools, of the diversity of haemosporidian parasites (among which the agents of human malaria are the best known) has generally led to rearrangements of traditional classifications. In this study, we explored the diversity of haemosporidian parasites infecting vertebrate species (particularly mammals, birds and reptiles) living in the forests of Gabon (Central Africa), by analyzing a collection of 492 bushmeat samples. We found that samples from five mammalian species (four duiker and one pangolin species), one bird and one turtle species were infected by haemosporidian parasites. In duikers (from which most of the infected specimens were obtained), we demonstrated the existence of at least two distinct parasite lineages related to Polychromophilus species (i. e., bat haemosporidian parasites) and to sauropsid Plasmodium (from birds and lizards). Molecular screening of sylvatic mosquitoes captured during a longitudinal survey revealed the presence of these haemosporidian parasite lineages also in several Anopheles species, suggesting a potential role in their transmission. Our results show that, differently from what was previously thought, several independent clades of haemosporidian parasites (family Plasmodiidae) infect mammals and are transmitted by anopheline mosquitoes

    Inter-individual variations of human mercury exposure biomarkers: a cross-sectional assessment

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    BACKGROUND: Biomarkers for mercury (Hg) exposure have frequently been used to assess exposure and risk in various groups of the general population. We have evaluated the most frequently used biomarkers and the physiology on which they are based, to explore the inter-individual variations and their suitability for exposure assessment. METHODS: Concentrations of total Hg (THg), inorganic Hg (IHg) and organic Hg (OHg, assumed to be methylmercury; MeHg) were determined in whole blood, red blood cells, plasma, hair and urine from Swedish men and women. An automated multiple injection cold vapour atomic fluorescence spectrophotometry analytical system for Hg analysis was developed, which provided high sensitivity, accuracy, and precision. The distribution of the various mercury forms in the different biological media was explored. RESULTS: About 90% of the mercury found in the red blood cells was in the form of MeHg with small inter-individual variations, and part of the IHg found in the red blood cells could be attributed to demethylated MeHg. THg in plasma was associated with both IHg and MeHg, with large inter-individual variations in the distribution between red blood cells and plasma. THg in hair reflects MeHg exposure at all exposure levels, and not IHg exposure. The small fraction of IHg in hair is most probably emanating from demethylated MeHg. The inter-individual variation in the blood to hair ratio was very large. The variability seemed to decrease with increasing OHg in blood, most probably due to more frequent fish consumption and thereby blood concentrations approaching steady state. THg in urine reflected IHg exposure, also at very low IHg exposure levels. CONCLUSION: The use of THg concentration in whole blood as a proxy for MeHg exposure will give rise to an overestimation of the MeHg exposure depending on the degree of IHg exposure, why speciation of mercury forms is needed. THg in RBC and hair are suitable proxies for MeHg exposure. Using THg concentration in plasma as a measure of IHg exposure can lead to significant exposure misclassification. THg in urine is a suitable proxy for IHg exposure

    Reduced antioxidant defense in early onset first-episode psychosis: a case-control study

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    Background:Our objective is to determine the activity of the antioxidant defense system at admission in patients with early onset first psychotic episodes compared with a control group. Methods: Total antioxidant status (TAS) and lipid peroxidation (LOOH) were determined in plasma. Enzyme activities and total glutathione levels were determined in erythrocytes in 102 children and adolescents with a first psychotic episode and 98 healthy controls. Results: A decrease in antioxidant defense was found in patients, measured as decreased TAS and glutathione levels. Lipid damage (LOOH) and glutathione peroxidase activity was higher in patients than controls. Our study shows a decrease in the antioxidant defense system in early onset first episode psychotic patients. Conclusions: Glutathione deficit seems to be implicated in psychosis, and may be an important indirect biomarker of oxidative stress in early-onset schizophrenia. Oxidative damage is present in these patients, and may contribute to its pathophysiology

    New Keywords: Migration and Borders

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    “New Keywords: Migration and Borders” is a collaborative writing project aimed at developing a nexus of terms and concepts that fill-out the contemporary problematic of migration. It moves beyond traditional and critical migration studies by building on cultural studies and post-colonial analyses, and by drawing on a diverse set of longstanding author engagements with migrant movements. The paper is organized in four parts (i) Introduction, (ii) Migration, Knowledge, Politics, (iii) Bordering, and (iv) Migrant Space/Times. The keywords on which we focus are: Migration/Migration Studies; Militant Investigation; Counter-mapping; Border Spectacle; Border Regime; Politics of Protection; Externalization; Migrant Labour; Differential inclusion/exclusion; Migrant struggles; and Subjectivity

    The Hippoboscidae (Insecta: Diptera) from Madagascar, with new records from the “Parc National de Midongy Befotaka”

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    The Hippoboscidae or “louse-flies” is a family of pupiparous Diptera, which in their adult stage are ectoparasites of mammals and birds. This paper presents a comprehensive review of Malagasy Hippoboscidae. In total, amongst the 213 species of this family known worldwide, 14 have been reported in Madagascar, among which six are considered as endemic to the Malagasy region. In addition, data are presented from a collection of 17 Hippoboscidae obtained from seven species of forest-dwelling birds in the “Parc National de Midongy Befotaka”, southeastern Madagascar, in 2003. The flies in this collection belong to three different species: Icosta malagasii (one), Ornithoica podicipis (ten) and Ornithoctona laticornis (six). The two former species were previously only known from single specimens in museum collections; the later species is distributed across much of the Afrotropical region and the records presented herein are the first for Madagascar. All the seven bird species are new hosts for hippoboscids. We present the first description of the male of Icosta malagasii. An illustrated dichotomous determination key of the 14 Malagasy species, based on morphological criteria only, is presented

    System integration: Condition for success. The case of Hammarby Sjöstad and Eva-Lanxmeer

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    Today, many new urban areas, such as cities, towns, villages, or districts, are being built worldwide and their completion requires the development of a number of infrastructures. Traditionally, these infrastructures are planned in parallel. However, increased environmental awareness is pushing cities to improve their environmental performance. One way to do so is by systems integration (e.g. connecting drinking water pumping with energy production). The aim of this paper is to show how different actor networks lead to different process of integration. We especially focus on the influence of actor participation during the design phase. To do so, two case studies are presented: Hammarby Sjöstad in Sweden and EVALanxmeer in the Netherlands.Technology, Policy and Managemen

    Limited association between <i>Wolbachia</i> and <i>Plasmodium falciparum</i> infections in natural populations of the major malaria mosquito <i>Anopheles moucheti</i>

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    International audienceSince the discovery of natural malaria vector populations infected by the endosymbi-ont bacterium Wolbachia, a renewed interest has arisen for using this bacterium as analternative for malaria control. Among naturally infected mosquitoes, Anopheles mou-cheti, a major malaria mosquito in Central Africa, exhibits one of the highest preva-lences of Wolbachia infection. To better understand whether this maternally inheritedbacterium could be used for malaria control, we investigated Wolbachia influence inAn. moucheti populations naturally infected by the malaria parasite Plasmodium fal-ciparum. To this end, we collected mosquitoes in a village from Cameroon, CentralAfrica, where this mosquito is the main malaria vector. We found that the prevalenceof Wolbachia bacterium was almost fixed in the studied mosquito population, andwas higher than previously recorded. We also quantified Wolbachia in whole mosqui-toes and dissected abdomens, confirming that the bacterium is also elsewhere than inthe abdomen, but at lower density. Finally, we analyzed the association of Wolbachiapresence and density on P. falciparum infection. Wolbachia density was slightly higherin mosquitoes infected with the malaria parasite than in uninfected mosquitoes.However, we observed no correlation between the P. falciparum and Wolbachia densi-ties. In conclusion, our study indicates that naturally occurring Wolbachia infection isnot associated to P. falciparum development within An. moucheti mosquitoes

    Exploring the diversity of blood-sucking diptera in caves of Central Africa

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    Caves house pathogenic microorganisms, some of which are transmitted by blood-sucking arthropods. In Africa, previous studies identified mosquitoes, sand flies and biting midges as the main potential vectors of cave-dwelling pathogens. However, to understand their involvement in pathogen spillover, it is crucial to characterize their diversity, community composition and dynamics. Using CDC light traps, we collected hematophagous Diptera in six caves of Gabon during one-shot or longitudinal sampling, and investigated their species diversity and dynamics in relation with external rainfall. Overall, we identified 68 species of mosquitoes, sand flies and biting midges, including 45 new records for Gabon. The dominant species were: Uranotaenia nigromaculata, Anopheles smithii s. l., Culex. rima group and Culex quasiguiarti for mosquitoes, Spelaeophlebotomus gigas and Spelaeomyia emilii for sand flies and the Culicoides trifasciellus group and Culicoides fulvithorax for biting midges. The survey revealed that species assemblages were cave-specific and included mainly troglophilous and trogloxenous species. Both diversity and abundance varied according to the cave and sampling time, and were significantly associated with rainfall. These associations were modulated by the cave specific environmental conditions. Moreover, the presence of trogloxenous and troglophilous species could be of high significance for pathogen transfers between cave and epigeous hosts, including humans
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