Étude de la faune microbienne et des paramètres physico-chimiques du tractus digestif d’annélides oligochètes, récoltés à Ebebda et à Nkolbikogo (région du Centre Cameroun)

The study focuses firstly on the morphological analysis of ciliates and secondly the variation in abundance of acaryotes and prokaryotes of the digestive tract of annelids Oligochaetes collected in the Center Region of Cameroon. In addition, the physicochemical parameters that influence the seriation of these microorganisms along the digestive tract of their hosts were analysed.The morphological study is based on the techniques of impregnation of specimens with the ammoniacal silver carbonate, the DAPI and the Feulgen nuclear staining. The surveys carried out on the annelid oligochaetes of the family of Glossoscolecidae have anabled the description of twenty species of ciliates belonging to Heterotrichs, Hysterocinetidae and Astomes. Amoung Heterotrichs, have been described three species of the genus Nyctotherus characterized by the presence of an apical secant system on their right side and a species of the genus Nyctotheroïdes characterized by the existence of three secant systems on their two sides: one on the right side and two on the left. Up to now, the presence of Heterotrichs was unsuspected in Glossoscolecidae. In Hysterocinetidae, the description of nine new species demonstrates the existence of four different types of skeletal pattern. The first type, present four superimposed and antagonistic skeletal fibre layers, corresponds to that of the genus Ptychostomum. The second type is characterized by the existence of an unorganized field of fibrillary structures forming a dense and undivided mass in the central part of the suction cup, for which a new genus is created: Ptychostomoïdes. The third type, present in the genus Proptychotomoïdes, is characterized by the existence of a glabrous surface in the central area of the adhesive apparatus. In the genus Thurstonia, an uncialiated kidney shape surface bordered subsequently by two mobile lips deprived of skeletal fibers was observed. This morphological diversity within Hysterocinetidae requires a new approach of the systematic in this group. In some Astomes (Almophrya bivacuolata and A. mediovacuolata), the analysis of the morphological variations of the nuclear apparatus allowed us to highlight important digitations and the presence of dark bands in the H macro-nucleus structure of the small cellular types, as well as the presence of intermediate forms between H and X macronucleus in these two species. In Almophrya laterovacuolata, the disposition of the vacuolar apparatus is variable: either two longitudinal lines are arranged among branches of the H macronucleus, or two longitudinal lines are out of the H macronucleus branches. These longitudinal lines may also be arranged without obvious order among the H macronucleus branches. Given that the identification within the genus Almophrya is specifically based on the number and the arrangement of vacuoles, a revision of these criteria is required. Four new species belonging to genera Anoplophrya, Hoplitophrya and Dicontophrya were also described in Astomes.In addition to the description of two new genera in Hysterocinetidae, four species in Heterotrichs, and seven species in Astomes, the technique of the cytometry in flow enabled us to highlight an unsuspected population of viruses in the digestive tract of the Glossoscolecidae as well as a population of bacteria not less important.The technique of aspiration under a vacuum pump allowed us to isolate and collect the intestinal liquid in three portions of the digestive tract of Alma emini. The correlations carried out between physico-chemical parameters and ciliates biomass held our attention. These results suggest that each portion of the digestive tract of Alma emini is a set of biotope niches, and microhabitats in which a large number of physical and chemical factors create ecological niches more suitable to a species or a group of species. This might explain the striation and the variation of abundance of the microfauna along the digestive tract of oligochaetes annelids.L’étude porte sur les analyses morphologiques des Protozoaires Ciliés et sur la variation d’abondance de virus et de bactéries du tube digestif d’annélides oligochètes de la famille des Glossoscolecidae récoltés dans la région du Centre Cameroun. De plus, les paramètres physico-chimiques susceptibles d’influencer la sériation de ces microorganismes le long du tube digestif de leurs hôtes ont été analysés. L’étude morphologique est basée sur les techniques d’imprégnation des spécimens au carbonate d’argent ammoniacal pyridiné et à la coloration au Di Aminido Phenyl Indol. Les prospections effectuées ont permis la description de vingt espèces de Ciliés appartenant aux Hétérotriches, Hysterocinetidés et Astomes. Chez les Hétérotriches dont la présence jusqu'ici était insoupçonnée chez les Glossoscolecidae, trois espèces du genre Nyctotherus ont été décrites ; caractérisées par la présence d’un système sécant apical sur leur face droite. Une espèce du genre Nyctotheroïdes a été décrite. Elle est caractérisée par l’existence de trois systèmes sécants dont un apical sur la face droite et deux (apical et caudal) sur la face gauche. Chez les Hysterocinetidés, la description de neuf espèces nouvelles démontre l’existence, au niveau de l’appareil adhésif de quatre types différents de topographies d’armature squelettique. Le premier, qui présente quatre strates de fibres squelettiques superposées et antagonistes, correspond à celui du genre Ptychostomum. Le second est caractérisé par l’existence d’un champ inorganisé de structures fibrillaires formant une masse dense et indivise dans la partie centrale de la ventouse, pour lequel un nouveau genre est créé : le genre Ptychostomoïdes. Le troisième type se distingue du précèdent par l’existence d’une aire glabre dans la région centrale de l’appareil adhésif. En fin le quatrième type, caractéristique du genre Thurstonia présente une aire non ciliée réniforme bordée postérieurement par deux lèvres mobiles et dépourvue de fibres squelettiques. Cette diversification morphologique au sein des Hysterocinetidés semble devoir imposer une nouvelle approche de la systématique de ce groupe. Les Ciliés Astomes Almophrya bivacuolata et A. mediovacuolata sont caractérisés par un macronoyau soit en X, en H, soit intermédiaire entre X et H. L’étude des variations morphologiques de l’appareil nucléaire chez ces espèces d’Almophrya révèle d’importantes digitations, des bandes sombres et d’interbandes dans la structure du macronoyau en H des petits types cellulaires. Chez A. laterovacuolata, la disposition de l’appareil vacuolaire est très variable : deux rangées longitudinales entre les branches du macronoyau en H; deux rangées longitudinales hors des branches de celui-ci ; sans ordre évident entre ses branches. Une révision des critères d’identification des Ciliés Almophrya semble devoir s’imposer. Quatre espèces nouvelles appartenant aux genres Anoplophrya, Hoplitophrya et Dicontophrya ont également été décrites chez les Astomes. Par ailleurs, la technique de la cytométrie en flux nous a permis de mettre en évidence une population jusqu’alors insoupçonnée de virus dans le tractus digestif des vers Glossoscolecidae ainsi qu’une population non moins importante de bactéries. La technique d’aspiration sous une pompe à vide a permis d’isoler et de recueillir le liquide intestinal du tube digestif de Alma emini. Les corrélations effectuées entre les paramètres physico-chimiques et les variations d’abondances des Ciliés ont été significatives. Ces résultats laissent supposer que chaque portion du tractus digestif de Alma emini est un ensemble de biotopes, de microhabitats dans lesquels un grand nombre de facteurs physiques et chimiques créent des niches écologiques plus favorables à une espèce ou à un groupe d’espèces. Ceci expliquerait la sériation et la variation d’abondance de la microfaune le long du tube digestif des annélides oligochètes

QUALITE DES INSTITUTIONS, ACCES AU CREDIT BANCAIRE ET CROISSANCE ÉCONOMIQUE EN AFRIQUE SUB-SAHARIENNE

Summary: The objective of this paper is to assess the effect of the quality of institutions in the relationship between bank credit and economic growth in the countries of Sub-Saharan Africa. To achieve this, econometric estimates were made using the Generalized Moment Method (MMG) in a dynamic panel of 36 countries in the area over the period from 2000 to 2018. The results obtained show that corruption and political instability have a negative effect on the level of bank credit granted to the private sector. The weakness of the legal framework has a negative effect on the level of bank credit granted to the private sector, thus limiting economic growth. This low level of democracy in these countries therefore has the effect of amplifying this pro-cyclical behavior of gross domestic product per capita. The independence of the central bank, an effective legal framework, political stability and a low level of corruption greatly reduce credit constraints and stimulate lending. The quality of institutions has optimal potential for promoting economic growth in Sub-Saharan Africa

Évaluation des caractéristiques des stomates chez le palmier à huile (Elaeis guineensis Jacq.)

Objectif: l’objectif principal de cette étude est de déterminer les paramètres caractéristiques des stomates chez Elaeis guineensis Jacq actuel.Méthodologie et résultats: Les paramètres comme la densité, la longueur et la largeur des stomates ont été évalués en observant l’épiderme des feuilles au microscope. Ainsi, le matériel adulte (dura, pisifera et, tenera) en champ et le matériel jeune (plants de tenera en pépinière et plants de tenera en pré pépinière) ont été considérés. Les résultats ont montré que, sur la face inférieure des feuilles, la densité stomatique est plus importante chez le matériel adulte 50,32 stomates par mm2 que chez le matériel jeune 23,88 stomates par mm2 et, sur la face supérieure des feuilles, cette situation s’inverse 4,77 stomates par mm2 contre 9,21 stomates par mm2. Les stomates sur la face supérieure des feuilles sont plus longs et larges que ceux observés sur la face inférieure des feuilles pour tous les matériels. Les stomates du matériel adulte sont aussi plus longs que ceux du matériel jeune. Pour tous les paramètres étudiés, la face inférieure apparaît la plus indiquée pour caractériser des stomates chez le palmier à huile.Conclusion et application des résultats: cette présente étude montre l’importance des stomates dans la caractérisation du niveau de ploïdie du palmier à huile. Ainsi, les résultats obtenus peuvent s’appliquer dans les recherches des plantes ayant une fertilité plus intéressante en s’appuyant sur la polyploïdisation.Mots clés: Elaeis guineensis, stomates, caractéristiquesEnglish AbstractObjective: To determine the characteristics of stomata parameters in Elaeis guineensis Jacq. Current.Methodology and results: Parameters such as the density, the length and with of stomata were evaluated by observing the leaf epidermis microscopically. Thus, adult material (dura, pisifera and tenera) field and the young material (tenera nursery plant and prenursery tenera plant) were considered. The results showed that on  the underside of leaves, stomata density was greater in adult material 50.32 stomata per mm2 than in younger material 23.88 stomata per mm2 on the upper leaf surface this reverses stomata per mm2 4.77 against 9.21 stomata per mm2. Stomata on the upper leaf surface are longer and wider than those seen on the underside of leaves for all materials. Stomata adult materials are also longer than those of young material. For all the parameters studied, the underside of leaves appears most indicated to characteristerize the stomata in the oil palm.Conclusion and application of results: this present study shows the importance of stomata in the characterization of the ploidy level of the oil palm. So, results can be applied in the research of plant with a more interesting fertility based on the polyploidization.Keywords: Elaeis guineensis, stomata, characteristic

Les teneurs en phytohormones des organes aériens de Faidherbia albida (Del) A. Chevalier au cours de la période froide et sèche au Burkina Faso

Objectif: L’objectif de cette étude est d’évaluer les teneurs en phytohormones dans les organes aériens de la plante au cours de la période froide et sèche. Faidherbia albida est une espèce qui perd ses feuilles en saison pluvieuse contrairement aux autres plantes de savane.Méthodologie et résultats: Des observations phénologiques ont été effectuées sur douze pieds sélectionnés suivant trois tranches d’âge : plus de 30 ans, entre 15 à 25 ans et moins de 15 ans. Des dosages spectrométriques d'auxine, de gibbérelline et de kinétine ont été effectués sur des échantillons de feuilles, de rameaux et d’écorces de tronc. Les observations ont révélé un début de feuillaison durant la période froide qui s’est poursuivie jusqu’à la fin du mois de janvier. Les dosages ont donné des teneurs en phytohormone significativement variables en fonction des organes. L’analyse statistique a révélé des différences hautement significatives (P=0,005) entre les tranches d’âge des pieds. Comparativement à l’auxine et à la kinétine, la teneur en gibbérelline est plus importante dans les organes. La plus forte teneur en gibbérelline est notée dans les feuilles des pieds âgés de moins de 15 ans. Il ressort une corrélation positive entre la gibbérelline et la kinétine (R = 0,60). L’analyse des paramètres climatiques et de la teneur en phytohormones met en évidence une corrélation linéaire significative entre l’auxine et la température (Coéfficient de corrélation = 0,29) et entre la gibbérelline et l’hygrométrie (Coefficient de corrélation = 0,27).Conclusion et application des résultats: Cette étude fournit des informations importantes sur l’état physiologique de Faidherbia albida pouvant contribuer à la prédiction de son comportement. Ainsi, les résultats obtenus peuvent s’appliquer dans la recherche de technique d’amélioration et de multiplication rapide de l’espèce.Mots clés: Faidherbia albida, période froide et sèche, phytohormones, organes aériensEnglish AbstractObjective: The objective of this study is to assess the levels of plant hormone in the aerial parts of the plant during the cold and dry period. Faidherbia albida is a species that sheds its leaves during the rainy season unlike other savanna plants.Methodology and Results: phenological observations were performed on twelve feet selected in three age groups : 30 years, 15 to 30 years and under 15. Spectrometric assays auxin, gibberellin and kinetin were carried out in the leaves, branches and trunk bark. The findings revealed an early leafing during the cold period that continued until the end of January. The assays returned grades significantly var iables in phytohormone in the organs. The statistical analysis revealed highly significant differences (P = 0.005) between the ages of feet. Compared with auxin and kinetin, gibberellin content is higher in organs but the highest is noted in older leaves feet shorter than 15 years. It follows a positive correlation between gibberellin and kinetin (R = 0.60). Analysis of climatic parameters and the content of phytohormones highlights a significant linear correlation between auxin and temperature (Correlation coefficient = 0.29) and between gibberellin and humidity (Correlation coefficient = 0.27).Conclusion and Application of the results: This study provides important information about the physiological state of albida can contribute to the prediction of behavior. Thus, the results can be applied in the search for technical improvement and rapid multiplication of the species. Furthermore the results can be applied in agriculture in search of new fertilizers and soil in the quality of the coupling livestock feed.Keywords: Faidherbia albida, cold and dry period, plant hormones, aerial organ

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

Distribution of Astomatia Schewiakoff, 1896 and Hysterocinetidae Diesing, 1866 (Ciliophora, Oligohymenophora) along the digestive tract of Alma emini (Oligochaete, Glossoscolecidae) is correlated with physico-chemical parameters

International audienceThe paper demonstrates the influence of physico-chemical parameters on the distribution of endocommensal ciliates through the gut of the earthworm Alma emini. We measured physico-chemical parameters of the intestinal liquid extracted with the vacuum aspiration technique and concomitantly recorded biological parameter (species abundance). Furthermore, correlation analysis between physico-chemical parameters and biological parameter was performed in different compartments. In the foregut, among the eleven species of Astomatia recorded, correlation was significant between Metaracoelophrya intermedia, Coelophrya roquei and Water Content (WC = 46.94 ± 7.77%). In the midgut, among the nine species of Hysterocinetidae recorded, a significant correlation was observed between Metaptychostomum ebebdae, Ptychostomum macrostomum and Electric Conductivity (EC = 84.55 ± 12.94 μS/ cm). In the same compartment, a significant correlation was also observed between Ptychostomum macrostomum and Total Dissolved Substance (TDS = 16.20 ± 3.46%). In the hindgut, eight species of Astomatia were found, among which significant correlation was obtained between Coelophrya roquei and Hydrogen potential (pH = 7.35 ± 0.16). In the same compartment, taking into account the eleven species of Hysterocinetidae recorded, a significant correlation was also obtained between Ptychostomum macrostomum and pH; Ptychostomum commune and WC (28.84 ± 3.97%). These results suggest that each part of the digestive tract of A. emini can be considered as a set of natural microhabitats in which certain physico-chemical factors generate ecological niches suitable for one or another group of species

Traduire vers la langue des signes française : plein phare sur la formation

Élise Leroy Selon l’article L 312-9-1 de la loi n° 2005-102 en date du 11 février 2005, « la langue des signes française est reconnue comme une langue à part entière » et elle a « un statut de langue de la République au même titre que le français ». Ainsi, nombre d’établissements publics doivent proposer un accueil adapté au public sourd (sous-entendu pratiquant la langue des signes) tant dans leurs locaux – guichet avec une personne pratiquant la LSF ou via un service d’interprétation à dis..

AGRO-MORPHOLOGICAL CHARACTERIZATION OF TWO RICE VARIETIES FROM JAPAN; ORYSA SATIVA L. AND FOUR NERICAS VARIETIES IN AN AGRO-ECOLOGICAL ZONE OF THE TOWN OF YAOUNDE (CAMEROON); COMPARATIVE STUDY OF THEIR PERFORMANCES

International audienceThe performances of two rice species of the genus Oryza were evaluated by considering parameters such as the number of panicle per rice plant, the number of primary branches of the panicles, panicle length, the plant height, the number of grains and empty balls per panicle. It appears that O. sativa from Japan has a number of empty balls less than NERICA’s varieties from Africa. We also noted that O. sativa has the highest number of panicles per rice plant (a mean of 14.05 ± 6.14). However, the number of grains per panicle NERICA’s varieties was very high (a mean of 164 ± 38.82) and therefore they shows more attractive characters than Orysa sativa lines. The differences were statistically significant above all the parameters considered in both African and Japan rice studied. A significant correlation that was negative has been observed between the number of panicles per rice plant and the number of primary branches per panicle within the NERICA 9 variety (P <0.05). The correlation was highly significant and positive (P <0.001) between the number of primary branches per panicle and the number of grain per panicle. These results suggest another demonstration of the hybrid vigor of NERICA varieties

Projected future daily characteristics of African precipitation based on global (CMIP5, CMIP6) and regional (CORDEX, CORDEX-CORE) climate models

We provide an assessment of future daily characteristics of African precipitation by explicitly comparing the results of large ensembles of global (CMIP5, CMIP6) and regional (CORDEX, CORE) climate models, specifically highlighting the similarities and inconsistencies between them. Results for seasonal mean precipitation are not always consistent amongst ensembles: in particular, global models tend to project a wetter future compared to regional models, especially over the Eastern Sahel, Central and East Africa. However, results for other precipitation characteristics are more consistent. In general, all ensembles project an increase in maximum precipitation intensity during the wet season over all regions and emission scenarios (except the West Sahel for CORE) and a decrease in precipitation frequency (under the Representative Concentration Pathways RCP8.5) especially over the West Sahel, the Atlas region, southern central Africa, East Africa and southern Africa. Depending on the season, the length of dry spells is projected to increase consistently by all ensembles and for most (if not all) models over southern Africa, the Ethiopian highlands and the Atlas region. Discrepancies exist between global and regional models on the projected change in precipitation characteristics over specific regions and seasons. For instance, over the Eastern Sahel in July–August most global models show an increase in precipitation frequency but regional models project a robust decrease. Global and regional models also project an opposite sign in the change of the length of dry spells. CORE results show a marked drying over the regions affected by the West Africa monsoon throughout the year, accompanied by a decrease in mean precipitation intensity between May and July that is not present in the other ensembles. This enhanced drying may be related to specific physical mechanisms that are better resolved by the higher resolution models and highlights the importance of a process-based evaluation of the mechanisms controlling precipitation over the region

Effects of Tumor Microenvironment Heterogeneity on Nanoparticle Disposition and Efficacy in Breast Cancer Tumor Models

Tumor cells are surrounded by a complex microenvironment. The purpose of our study was to evaluate the role of heterogeneity of the tumor microenvironment in the variability of nanoparticle (NP) delivery and efficacy