Caractéristique Physico-Chimique Etdynamique des Formes Environnementales des Coccidies Entériques Dans Les Eaux De Sources, Puits et Cours D’eau dans La Commune d’Akono(Cameroun, Afrique Centrale)

L’objectif de cette étude vise à évaluer la qualité physico-chimique et parasitologique des eaux de sources, des puits et du cours d’eau dans la commune d’Akono. L’étude entreprise d’Avril 2017 à Mars 2018 a permis d’effectuer les échantillonnages pour des analyses physico-chimiques et parasitologiques. Les paramètres physiques tels que la température (T °C), la turbidité, les matières en suspension (MES) et la couleur et quelques paramètres chimiques : le pH, la conductivité, l’oxygène, l’oxydabilité, les nitrates, les nitrites, l’azote ammoniacal ont été mesurés. Les eaux de la commune d’Akono sont légèrement acides (Ph=6,1±0,3 UC) et faiblement minéralisées (conductivité=95,5±67,5 µS/Cm). Les teneurs en azote obtenues sont inférieures aux normes. De fortes corrélations ont été mises en évidence entre la conductivité, la turbidité, la couleur, les MES et les densités des oocystes obtenues. Les analyses parasitologiques des échantillons d’eau ont permis d’identifier des oocystes du genre Cryptosporidium sp (141 oocystes/L), de Cyclospora cayetanensis (52 oocystes/L) et d’Isospora belli (40 oocystes/L). Les eaux ont été soumises à une pollution d’origine fécale dans la commune d’Akono. L’usage de ces eaux pourrait présenter un risque sanitaire pour les populations. The objective of this study is intended to assess the physico-chemical quality and the parasitological quality of spring waters, wells and stream in the Akono city council. The study was carried out from April 2017 to March 2018. Within this time, samples for physicochemical and Parasitological analyses where collected. Physical parameters such as temperature (T °C), turbidity, suspended solids (SS) and the color and some chemical parameters: pH, conductivity, oxygen, the oxidability, nitrates, nitrites, ammonia were measured. The waters of Akono municipality are slightly acidic with an average pH of 6.1±0.3 UC. These waters are lowly mineralized with an average electrical conductivity of 95.5±67.5 µS/cm. The concentrations of nitrogenous compounds obtained are slightly below substandard. Strong correlations were observed between electrical conductivity, turbidity, color, SS by the oocysts and densities obtained. Parasitological analyses were made by observation using an optical microscope 40 X objective. The results reveal the presence of oocysts of Cryptosporidium sp. (141oocysts/L), Cyclospora cayetanensis (52oocysts/L) and Isospora belli (40oocysts/L). The water was subjected to pollution of faecal origin in the Akono municipality. The use of this waters could present a health risk for the population

Description of five new species of hysterocinetian ciliates (Ciliophora, Hysterocinetidae), endocommensal in a terrestrial oligochaete of the genus Alma from Cameroon

International audienceStudies on five new species of hysterocinetian ciliates, endocommensal within a terrestrial oligochaete from the genus Alma (Cameroon), reveal the existence of three distinct types of cytoskeletal topography within their adhesive apparatus. In the first topographical type, four superimposed antagonistic strata of skeletal fibres that correspond to the arrangement observed in the genus Ptychostomum, Stein 1860 are found. The second topographical type is characterized by the existence of an unorganized field of fibrillar structures forming a single dense mass in the central part of the sucker. For this, a new genus is created: Ptychostomoides, Nana, Fokam, Ntoungwa et al. n. g. The third type present in the genus Proptychostomoides, Nana, Fokam, Ntoungwa et al. n. g. differs from the latter by the existence of a bare patch within the central region of the adhesive apparatus. This new evidence of morphological diversification within the Hysterocinetidae supports a new approach to the systematics of this group

Mapping of Schistosomiasis and Soil-Transmitted Helminthiasis in the Regions of Centre, East and West Cameroon

Schistosomiasis and soil-transmitted helminthiasis (STH) are a major public health problem in Cameroon. The national control strategy of these diseases was based on historical data collected 25 years ago, which might be outdated in some situations due to several factors including control activities, improved or degraded sanitation and hygiene, socio-economic improvement and disease transmission dynamics. To help planning, improving control strategies and evaluation of control activities, there was a need to update the distribution of schistosomiasis and STH. We conducted parasitological surveys in three regions of Cameroon, i.e. Centre, East and West. Our results showed a significant decrease of STH infection prevalence and intensities in all these three regions, in comparison to previous mapping data, with an overall decline of prevalence from 81.1–93% to 10.5–46.6%. These results show the positive impact of annual deworming campaigns, and illustrate the progressive success of the national programme for the control of schistosomiasis and STH in Cameroon. Furthermore, our results showed an increase of the number of high transmission foci of schistosomiasis, and allowed identifying new health districts requiring mass treatment with praziquantel, and those where deworming should be reinforced

Population genetic structure of the malaria vector Anopheles nili in sub-Saharan Africa

<p>Abstract</p> <p>Background</p> <p><it>Anopheles nili </it>is a widespread efficient vector of human malaria parasites in the humid savannas and forested areas of sub-Saharan Africa. Understanding <it>An. nili </it>population structure and gene flow patterns could be useful for the development of locally-adapted vector control measures.</p> <p>Methods</p> <p>Polymorphism at eleven recently developed microsatelitte markers, and sequence variation in four genes within the 28s rDNA subunit (ITS2 and D3) and mtDNA (COII and ND4) were assessed to explore the level of genetic variability and differentiation among nine populations of <it>An. nili </it>from Senegal, Ivory Coast, Burkina Faso, Nigeria, Cameroon and the Democratic Republic of Congo (DRC).</p> <p>Results</p> <p>All microsatellite loci successfully amplified in all populations, showing high and very similar levels of genetic diversity in populations from West Africa and Cameroon (mean Rs = 8.10-8.88, mean He = 0.805-0.849) and much lower diversity in the Kenge population from DRC (mean Rs = 5.43, mean He = 0.594). Bayesian clustering analysis of microsatellite allelic frequencies revealed two main genetic clusters in the dataset. The first one included only the Kenge population and the second grouped together all other populations. High Fst estimates based on microsatellites (Fst > 0.118, P < 0.001) were observed in all comparisons between Kenge and all other populations. By contrast, low Fst estimates (Fst < 0.022, P < 0.05) were observed between populations within the second cluster. The correlation between genetic and geographic distances was weak and possibly obscured by demographic instability. Sequence variation in mtDNA genes matched these results, whereas low polymorphism in rDNA genes prevented detection of any population substructure at this geographical scale.</p> <p>Conclusion</p> <p>Overall, high genetic homogeneity of the <it>An. nili </it>gene pool was found across its distribution range in West and Central Africa, although demographic events probably resulted in a higher level of genetic isolation in the marginal population of Kenge (DRC). The role of the equatorial forest block as a barrier to gene flow and the implication of such findings for vector control are discussed.</p

When Molecular Dimerization Induces Magnetic Bi‐Stability at the Metal–Organic Interface

Abstract 2D metal–organic frameworks have been recently proposed as a flexible platform for realizing new functional materials including quantum phases. Here, we present a method to create metal‐organic dimer complexes by on‐surface assembly on a metal substrate using low‐temperature scanning tunneling microscopy (STM) and spectroscopy (STS). We demonstrate that a dimer of Mn‐Phthalocyanine (MnPc)2 on a Ag(111) surface can be switched between two stable configurations upon a small conformational change controlled by STM manipulation. By means of density‐functional theory calculations, it is found that the two conformations correspond to an antiferromagnetic (AFM) and a ferromagnetic (FM) state respectively. Directly coordinated Mn atoms of the dimer lead to an AFM‐coupling whereas indirectly coordinated (shifted) Mn atoms lead to a FM‐coupling. Rarely seen in a molecular‐dimers with transition‐metal atoms, the FM‐AFM‐FM transition is thus readily on‐surface accessible. Furthermore, the two configurations of the switch are easily identified by their Kondo states, opening interesting routes in terms of both, writing (FM versus AFM states) and reading. These results pave the experimental route toward dimer‐based materials with complex magnetic structures of potential interest for application in spintronics, logics and computing

Dissociative excitation of NeD/sup +/

Measurements of NeD/sup +/ dissociative excitation cross section were obtained in Louvain-la-Neuve (UCL, Belgium) by using the animated crossed electron-ion beam method. The electronic structure of the system was calculated by using quantum chemistry calculations for the NeD/sup +/ ion and ab initio electron scattering calculations using the complex Kohn variational method for the resonant NeD neutral complex formed by the temporary capture of the electron by the ion. The cross section for dissociative excitation are then calculated below the second excitation thresholds of the ion where the process is dominated by a series of doubly-excited resonance states. Theory and experiment are then compared.Anglai

[Revision of of the subfamily of Metaracoelophryinae de Puytorac 1972 (Oligohymenophora: Hoplytophryida: Hoplytophryidae), astome ciliates of the digestive tract of Oligochaeta worms of Africa: description of five new species].

International audienceFive new species belonging to the astome ciliates, living in the digestive tract of Oligochaeta worms belonging to the genus Alma from Cameroon, have been described. The techniques used are: vital staining, staining of the nucleus with Diamidino Phenyl Indol (DAPI), scanning electron microscopy and silver staining method (Fernandez Galiano, 1976, 1994). This work confirms the presence of the genus Paracoelophrya and Dicoelophrya in the digestive track of the oligochaete Alma from Gabon and Cameroon; it helps to understand the general taxonomy of this Metaracoelophryinae subfamily. Moreover, the homogeneity of this group is confirmed and the phylogenetic relationship inside the Hoplitophryida order need more studies to be solved

Variable phylogeographic histories of five forest birds with populations in Upper and Lower Guinea: Implications for taxonomy and evolutionary conservation

This study evaluates phylogeographic structure in selected forest bird species distributed on either side of the Dahomey Gap in West Africa to extend analyses of avian diversification across the Guineo-Congolean forest. Mitochondrial DNA sequence data were collected for five species, including four with a break in distribution across the Dahomey Gap and one with a more continuous distribution. Data for the five focal species were included in a single analysis along with appropriate outgroup taxa, allowing estimates of divergence time on a common timescale. Both phylogeographic patterns and estimated divergence times were highly variable. In two cases (Green Hylia Hylia prasina and Yellow-whiskered Greenbul Eurillas latirostris), samples from east and west of the Dahomey Gap belong to divergent mitochondrial lineages, but with substantially older divergence in Eurillas (~4.1 MY). In Western Bluebill Spermophaga haematina, relatively divergent eastern and western lineages (~1.1 MY) were sampled in the same locality in eastern Ghana, suggesting east to west gene flow across the gap following earlier vicariance. In Forest Robin Stiphrornis erythrothorax, birds sampled within Ghana were from two highly divergent lineages (~1.9 MY), one of which is more closely related to birds from Cameroon and Equatorial Guinea, such that divergence across the Dahomey Gap was comparatively recent (~0.36 MY). For both Hylia and Stiphrornis, we corroborate recent studies documenting multiple divergent lineages within each genus, some of which may represent distinct species. Consistent with previous studies, our analysis shows that the Dahomey Gap can be a significant barrier to gene flow for species restricted to forest habitats. At the same time, individual species exhibit a broad range of divergence times and phylogeographic histories of variable complexity. We discuss the taxonomic implications of our results for each focal species.Histoires phylogéographiques variables de cinq oiseaux forestiers ayant des populations en Haute et Basse Guinée: implications pour la conservation taxonomique et évolutiveCette étude évalue la structure phylogéographique de certaines espèces d’oiseaux forestiers réparties de part et d’autre du Dahomey Gap en Afrique de l’Ouest, pour étendre les analyses de la diversification aviaire à travers la forêt guinéo-congolaise. Les données des séquences d’ADN mitochondrial ont été collectées pour cinq espèces, dont quatre présentant une rupture dans la distribution au niveau du Dahomey Gap alors que une espèce a une distribution beaucoup plus continue. Les données pour les cinq espèces étudiées ont été incluses dans une seule analyse, ensemble avec les taxons de groupes externes appropriés, permettant d’estimer le temps de divergence sur une échelle temporelle commune. Les tendances phylogéographiques tout comme les temps de divergence estimés, étaient hautement variables. Dans deux des cas (l’Hylia verte Hylia prasina et le Bulbul à moustaches jaunes Eurillas latirostris), des échantillons provenant de l’est et de l’ouest du Dahomey Gap appartiennent à des lignées mitochondriales divergentes, mais avec une divergence sensiblement plus ancienne chez Eurillas (~4,1 MA). Chez le Sénégali sanguin Spermophaga haematina, les lignées orientales et occidentales relativement divergentes (~1,1 MA, ont été échantillonnées dans la même localité, à l’est du Ghana, suggérant un flux génique de l’est à l’ouest à travers le Dahomey Gap suivant la précédente vicariance. Pour le Rougegorge de forêt Stiphrornis erythrothorax, les oiseaux échantillonnés au Ghana appartenaient à deux lignées très divergentes (~ 1,9 MA), dont l’une était plus proche des oiseaux du Cameroun et de la Guinée équatoriale, en sorte que la divergence à travers le Dahomey Gap était relativement récente (~ 0,36 MA). Pour Hylia et Stiphrornis, nous corroborons les études récentes documentant de multiples lignées divergentes au sein de chaque genre, dont certaines peuvent représenter des espèces distinctes. En accord avec des études précédentes, notre analyse montre que le Dahomey Gap peut constituer une barrière importante au flux de gènes pour les espèces restreintes aux habitats forestiers. Aussi, les espèces considérées individuellement, présentent une large gamme de temps de divergence et des histoires phylogéographiques d’une complexité variable. Nous examinons les implications taxonomiques de nos résultats pour chaque espèce étudiée.Keywords: Dahomey Gap, Guineo-Congolean forest, phylogeography, speciation, vicarianc

Absolute cross sections and kinetic energy release distributions for electron-impact dissociative excitation and ionization of NeD+

Absolute cross sections for electron impact dissociative excitation and ionization of NeD+ leading to the formation of singly and multiply charged products (D+, Ne+, Ne2+ and Ne3+) are reported, in the energy range from their respective thresholds to 2.5 keV. The animated crossed-beams method is used. For singly charged fragments, absolute cross sections are obtained separately for dissociative excitation and for dissociative ionization. Dissociative excitation is seen to be restricted to the low-energy range (<300 eV) and the D+ formation dominates over the Ne+ one. At the maximum (around 35 eV), absolute cross sections for dissociative excitation are found to be (3.6 +/- 0.8) x 10(-17) cm(2) and (6.3 +/- 1.4) x 10(-17) cm(2) for Ne+ and D+, respectively; the corresponding appearance energies are (9.1 +/- 0.5) eV and (10.0 +/- 0.5) eV. The absolute cross section for dissociative ionization (Ne++D+ formation) is found to be (7.1 +/- 1.4) x 10(-17) cm(2), around 155 eV, and the threshold energy is (26.8 +/- 0.5) eV. For multiply charged products, absolute cross sections are found, around the maximum, to be (5.4 +/- 0.5) x 10(-18) cm(2) and (18.2 +/- 2.6) x 10(-20) cm(2) for Ne2+ and Ne3+, respectively; the corresponding thresholds are (53.1 +/- 1.0) eV and (132 +/- 5) eV. Kinetic energy release distributions are determined for each detected ionic product. The presented potential energy curves correspond to dissociation channels, which are significant for the discussion of present results. At fixed electron energy, the cross sections for the various ionization channels are seen to decrease exponentially with the potential energy of each dissociated ion pair