Université Nangui Abrogoua

Land systems are the result of human interactions with the natural environment. Understanding the drivers, state, trends and impacts of different land systems on social and natural processes helps to reveal how changes in the land system affect the functioning of the socio-ecological system as a whole and the tradeoff these changes may represent. The Global Land Project has led advances by synthesizing land systems research across different scales and providing concepts to further understand the feedbacks between social-and environmental systems, between urban and rural environments and between distant world regions. Land system science has moved from a focus on observation of change and understanding the drivers of these changes to a focus on using this understanding to design sustainable transformations through stakeholder engagement and through the concept of land governance. As land use can be seen as the largest geo-engineering project in which mankind has engaged, land system science can act as a platform for integration of insights from different disciplines and for translation of knowledge into action.

Soil organisms, including earthworms, are a key component of terrestrial ecosystems. However, little is known about their diversity, their distribution, and the threats affecting them. We compiled a global dataset of sampled earthworm communities from 6928 sites in 57 countries as a basis for predicting patterns in earthworm diversity, abundance, and biomass. We found that local species richness and abundance typically peaked at higher latitudes, displaying patterns opposite to those observed in aboveground organisms. However, high species dissimilarity across tropical locations may cause diversity across the entirety of the tropics to be higher than elsewhere. Climate variables were found to be more important in shaping earthworm communities than soil properties or habitat cover. These findings suggest that climate change may have serious implications for earthworm communities and for the functions they provide.

The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.

Bixin, also known as annatto, is a seed-specific pigment widely used in foods and cosmetics since pre-Columbian times. We show that three genes from Bixa orellana, native to tropical America, govern bixin biosynthesis. These genes code for lycopene cleavage dioxygenase, bixin aldehyde dehydrogenase, and norbixin carboxyl methyltransferase, which catalyze the sequential conversion of lycopene into bixin. Introduction of these three genes in Escherichia coli engineered to produce lycopene induced bixin synthesis, thus expanding the supply of this economically important plant product.

The final outcome of infection by Trypanosoma brucei gambiense, the main agent of sleeping sickness, has always been considered as invariably fatal. While scarce and old reports have mentioned cases of self-cure in untreated patients, these studies suffered from the lack of accurate diagnostic tools available at that time. Here, using the most specific and sensitive tools available to date, we report on a long-term follow-up (15 years) of a cohort of 50 human African trypanosomiasis (HAT) patients from the Ivory Coast among whom 11 refused treatment after their initial diagnosis. In 10 out of 11 subjects who continued to refuse treatment despite repeated visits, parasite clearance was observed using both microscopy and polymerase chain reaction (PCR). Most of these subjects (7/10) also displayed decreasing serological responses, becoming progressively negative to trypanosome variable antigens (LiTat 1.3, 1.5 and 1.6). Hence, in addition to the "classic" lethal outcome of HAT, we show that alternative natural progressions of HAT may occur: progression to an apparently aparasitaemic and asymptomatic infection associated with strong long-lasting serological responses and progression to an apparently spontaneous resolution of infection (with negative results in parasitological tests and PCR) associated with a progressive drop in antibody titres as observed in treated cases. While this study does not precisely estimate the frequency of the alternative courses for this infection, it is noteworthy that in the field national control programs encounter a significant proportion of subjects displaying positive serologic test results but negative results in parasitological testing. These findings demonstrate that a number of these subjects display such infection courses. From our point of view, recognising that trypanotolerance exists in humans, as is now widely accepted for animals, is a major step forward for future research in the field of HAT.

The fall armyworm, Spodoptera frugiperda, a moth originating from tropical and subtropical America, has recently become a serious pest of cereals in sub-Saharan Africa. Biological control offers an economically and environmentally safer alternative to synthetic insecticides that are being used for the management of this pest. Consequently, various biological control options are being considered, including the introduction of Telenomus remus, the main egg parasitoid of S. frugiperda in the Americas, where it is already used in augmentative biological control programmes. During surveys in South, West, and East Africa, parasitized egg masses of S. frugiperda were collected, and the emerged parasitoids were identified through morphological observations and molecular analyses as T. remus. The presence of T. remus in Africa in at least five countries provides a great opportunity to develop augmentative biological control methods and register the parasitoid against S. frugiperda. Surveys should be carried out throughout Africa to assess the present distribution of T. remus on the continent, and the parasitoid could be re-distributed in the regions where it is absent, following national and international regulations. Classical biological control should focus on the importation of larval parasitoids from the Americas.

Mutualistic biotic interactions as among flowering plants and their animal pollinators are a key component of biodiversity. Pollination, especially by insects, is a key element in ecosystem functioning, and hence constitutes an ecosystem service of global importance. Not only sexual reproduction of plants is ensured, but also yields are stabilized and genetic variability of crops is maintained, counteracting inbreeding depression and facilitating system resilience. While experiencing rapid environmental change, there is an increased demand for food and income security, especially in sub-Saharan communities, which are highly dependent on small scale agriculture. By combining exclusion experiments, pollinator surveys and field manipulations, this study for the first time quantifies the contribution of bee pollinators to smallholders' production of the major cash crops, cotton and sesame, in Burkina Faso. Pollination by honeybees and wild bees significantly increased yield quantity and quality on average up to 62%, while exclusion of pollinators caused an average yield gap of 37% in cotton and 59% in sesame. Self-pollination revealed inbreeding depression effects on fruit set and low germination rates in the F1-generation. Our results highlight potential negative consequences of any pollinator decline, provoking risks to agriculture and compromising crop yields in sub-Saharan West Africa.

BACKGROUND: Temprano ANRS 12136 was a factorial 2 × 2 trial that assessed the benefits of early antiretroviral therapy (ART; ie, in patients who had not reached the CD4 cell count threshold used to recommend starting ART, as per the WHO guidelines that were the standard during the study period) and 6-month isoniazid preventive therapy (IPT) in HIV-infected adults in Côte d'Ivoire. Early ART and IPT were shown to independently reduce the risk of severe morbidity at 30 months. Here, we present the efficacy of IPT in reducing mortality from the long-term follow-up of Temprano. METHODS: For Temprano, participants were randomly assigned to four groups (deferred ART, deferred ART plus IPT, early ART, or early ART plus IPT). Participants who completed the trial follow-up were invited to participate in a post-trial phase. The primary post-trial phase endpoint was death, as analysed by the intention-to-treat principle. We used Cox proportional models to compare all-cause mortality between the IPT and no IPT strategies from inclusion in Temprano to the end of the follow-up period. FINDINGS: =0·94) on mortality. INTERPRETATION: In Côte d'Ivoire, where the incidence of tuberculosis was last reported as 159 per 100 000 people, 6 months of IPT has a durable protective effect in reducing mortality in HIV-infected people, even in people with high CD4 cell counts and who have started ART. FUNDING: National Research Agency on AIDS and Viral Hepatitis (ANRS).

Fungal biomasses are capable of treating metal-contaminated effluents with efficiencies several orders of magnitude superior to activated carbon (F-400) or the industrial resin Dowex-50. Additionally, fungal biomasses are susceptible to engineering improvements and regeneration of their capabilities. With regard to organic pollutants, excessive nutrients and dyes, fungi can remove them from wastewaters, leading to a decrease in their toxicities. However, the detoxification rates seem to be dependent on media and culture conditions. The postreatement by anaerobic bioprocesses of effluents that have been pretreated with fungi can lead to higher biogas than the original effluents. In addition to the degradation of organic pollutants, fungi produce added-value products such as enzymes (LiP, MnP, Lacc, amylase, etc.) and single-cell protein (SCP). Most research on fungal capacities to purify polluted effluents has been performed on a laboratory scale, hence there is a need to extend such research to pilot scale and to apply it to industrial processes.   Key words: Wastewaters, effluents, fungi, biodegradation, biosorption, decolourisation, value-added treatment.

BACKGROUND: Failure in detecting naturally occurring breeding sites of Aedes mosquitoes can bias the conclusions drawn from field studies, and hence, negatively affect intervention outcomes. We characterized the habitats of immature Aedes mosquitoes and explored species dynamics along a rural-to-urban gradient in a West Africa setting where yellow fever and dengue co-exist. METHODOLOGY: Between January 2013 and October 2014, we collected immature Aedes mosquitoes in water containers in rural, suburban, and urban areas of south-eastern Côte d'Ivoire, using standardized sampling procedures. Immature mosquitoes were reared in the laboratory and adult specimens identified at species level. PRINCIPAL FINDINGS: We collected 6,159, 14,347, and 22,974 Aedes mosquitoes belonging to 17, 8, and 3 different species in rural, suburban, and urban environments, respectively. Ae. aegypti was the predominant species throughout, with a particularly high abundance in urban areas (99.374%). Eleven Aedes larval species not previously sampled in similar settings of Côte d'Ivoire were identified: Ae. albopictus, Ae. angustus, Ae. apicoargenteus, Ae. argenteopunctatus, Ae. haworthi, Ae. lilii, Ae. longipalpis, Ae. opok, Ae. palpalis, Ae. stokesi, and Ae. unilineatus. Aedes breeding site positivity was associated with study area, container type, shade, detritus, water turbidity, geographic location, season, and the presence of predators. We found proportionally more positive breeding sites in urban (2,136/3,374, 63.3%), compared to suburban (1,428/3,069, 46.5%) and rural areas (738/2,423, 30.5%). In the urban setting, the predominant breeding sites were industrial containers (e.g., tires and discarded containers). In suburban areas, containers made of traditional materials (e.g., clay pots) were most frequently encountered. In rural areas, natural containers (e.g., tree holes and bamboos) were common and represented 22.1% (163/738) of all Aedes-positive containers, hosting 18.7% of the Aedes fauna. The predatory mosquito species Culex tigripes was commonly sampled, while Toxorhynchites and Eretmapodites were mostly collected in rural areas. CONCLUSIONS/SIGNIFICANCE: In Côte d'Ivoire, urbanization is associated with high abundance of Aedes larvae and a predominance of artificial containers as breeding sites, mostly colonized by Ae. aegypti in urban areas. Natural containers are still common in rural areas harboring several Aedes species and, therefore, limiting the impact of systematic removal of discarded containers on the control of arbovirus diseases.

Gut microbes play a crucial role in decomposing lignocellulose to fuel termite societies, with protists in the lower termites and prokaryotes in the higher termites providing these services. However, a single basal subfamily of the higher termites, the Macrotermitinae, also domesticated a plant biomass-degrading fungus (Termitomyces), and how this symbiont acquisition has affected the fungus-growing termite gut microbiota has remained unclear. The objective of our study was to compare the intestinal bacterial communities of five genera (nine species) of fungus-growing termites to establish whether or not an ancestral core microbiota has been maintained and characterizes extant lineages. Using 454-pyrosequencing of the 16S rRNA gene, we show that gut communities have representatives of 26 bacterial phyla and are dominated by Firmicutes, Bacteroidetes, Spirochaetes, Proteobacteria and Synergistetes. A set of 42 genus-level taxa was present in all termite species and accounted for 56-68% of the species-specific reads. Gut communities of termites from the same genus were more similar than distantly related species, suggesting that phylogenetic ancestry matters, possibly in connection with specific termite genus-level ecological niches. Finally, we show that gut communities of fungus-growing termites are similar to cockroaches, both at the bacterial phylum level and in a comparison of the core Macrotermitinae taxa abundances with representative cockroach, lower termite and higher nonfungus-growing termites. These results suggest that the obligate association with Termitomyces has forced the bacterial gut communities of the fungus-growing termites towards a relatively uniform composition with higher similarity to their omnivorous relatives than to more closely related termites.

Rhamnogalacturonans-I (RGs-I) are complex structural components of the (primary) cell wall. Their backbone, composed of the repeating diglycosyl [→2)-α-L-Rhap-(1→4)-α-D-GalpA-(1→], is believed to be branched at O-4/O-3 positions by 4 different side chain types, viz. (1→5)-α-L-arabinan, (1→4)-β-D-galactan, arabinogalactan-I, and sometimes with arabinogalactan-II. However, the fine structure of RGs-I remains somewhat enigmatic, as shown by various continuous findings, such as branches of galactoarabinan, arabinogalactan with a (1→6)-β-D-galactan core, and possibly (1→3)-rhamnan. This timely review is the first of its kind, highlighting the freak structural diversity and the functional versatility of RG-I, one of the two major structural domains of complex pectins.

BACKGROUND: Carotenoids are the most widespread group of pigments found in nature. In addition to their role in the physiology of the plant, carotenoids also have nutritional relevance as their incorporation in the human diet provides health benefits. In non-photosynthetic tissues, carotenoids are synthesized and stored in specialized plastids called chromoplasts. At present very little is known about the origin of the metabolic precursors and cofactors required to sustain the high rate of carotenoid biosynthesis in these plastids. Recent proteomic data have revealed a number of biochemical and metabolic processes potentially operating in fruit chromoplasts. However, considering that chloroplast to chromoplast differentiation is a very rapid process during fruit ripening, there is the possibility that some of the proteins identified in the proteomic analysis could represent remnants no longer having a functional role in chromoplasts. Therefore, experimental validation is necessary to prove whether these predicted processes are actually operative in chromoplasts. RESULTS: A method has been established for high-yield purification of tomato fruit chromoplasts suitable for metabolic studies. Radiolabeled precursors were efficiently incorporated and further metabolized in isolated chromoplast. Analysis of labeled lipophilic compounds has revealed that lipid biosynthesis is a very efficient process in chromoplasts, while the relatively low incorporation levels found in carotenoids suggest that lipid production may represent a competing pathway for carotenoid biosynthesis. Malate and pyruvate are efficiently converted into acetyl-CoA, in agreement with the active operation of the malic enzyme and the pyruvate dehydrogenase complex in the chromoplast. Our results have also shown that isolated chromoplasts can actively sustain anabolic processes without the exogenous supply of ATP, thus suggesting that these organelles may generate this energetic cofactor in an autonomous way. CONCLUSIONS: We have set up a method for high yield purification of intact tomato fruit chromoplasts suitable for precursor uptake assays and metabolic analyses. Using targeted radiolabeled precursors we have been able to unravel novel biochemical and metabolic aspects related with carotenoid and lipid biosynthesis in tomato fruit chromoplasts. The reported chromoplast system could represent a valuable platform to address the validation and characterization of functional processes predicted from recent transcriptomic and proteomic data.

Abstract Aim To predict the distribution of suitable environmental conditions ( SEC ) for eight A frican great ape taxa for a first time period, the 1990s and then project it to a second time period, the 2000s; to assess the relative importance of factors influencing SEC distribution and to estimate rates of SEC loss, isolation and fragmentation over the last two decades. Location Twenty‐two A frican great ape range countries. Methods We extracted 15,051 presence localities collected between 1995 and 2010 from 68 different areas surveyed across the A frican ape range. We combined a maximum entropy algorithm and logistic regression to relate ape presence information to environmental and human impact variables from the 1990s with a resolution of 5 × 5 km across the entire ape range. We then made SEC projections for the 2000s using updated human impact variables. Results Total SEC area was approximately 2,015,480 and 1,807,653 km 2 in the 1990s and 2000s, respectively. Loss of predicted SEC appeared highest for Cross River gorillas (−59%), followed by eastern gorillas (−52%), western gorillas (−32%), bonobos (−29%), central chimpanzees (−17%) and western chimpanzees (−11%). SEC for N igeria‐ C ameroon chimpanzees and eastern chimpanzees was not greatly reduced. Except for C ross R iver and eastern gorillas, the number of SEC patches did not change significantly, suggesting that SEC loss was caused mainly by patch size reduction. Main conclusions The first continent‐wide perspective of A frican ape SEC distribution shows dramatic declines in recent years. The model has clear limitations for use at small geographic scales, given the quality of available data and the coarse resolution of predictions. However, at the large scale it has potential for informing international policymaking, mitigation of resource extraction and infrastructure development, as well as for spatial prioritization of conservation effort and evaluating conservation effectiveness.

Polyhexamethylene guanidine hydrochloride (PHMGH), an antimicrobial biocide of the guanidine family, was tested for efficacy against quality-control strains of Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella choleraesuis, meticillin-resistant S. aureus (MRSA) and Escherichia coli. Bactericidal activity against S. aureus, P. aeruginosa and Salmonella choleraesuis was determined using the official methods of analysis of the Association of Official Analytical Chemists, with modifications as recommended by the Canadian General Standards Board. For MRSA and E. coli, the MIC and minimal bactericidal concentration were determined using the broth dilution technique. The experiments were carried out at 20 degrees C under a range of conditions including varying PHMGH concentration (0.001-0.1 %), contact time (0.5-10 min) and water type (distilled, tap and hard water). The phenol coefficient values determined with S. aureus, Salmonella choleraesuis and P. aeruginosa were 7.5, 6.1 and 5, respectively. No matter what type of water was used to make the dilutions, PHMGH killed MRSA and E. coli at concentrations as low as 0.04 and 0.005 % (w/v), respectively, within 1.5 min. The mode of action of PHMGH was elucidated by transmission electron microscopy: the cell envelope was broken, resulting in cell content leakage into the medium. The ultimate aim of this study was to show that PHMGH can be used as an odourless, colourless, non-corrosive and harmless disinfectant for hospital and household facilities.

BACKGROUND: Morbidity control of schistosomiasis relies on a single drug, praziquantel. The antimalarial drug mefloquine possesses interesting antischistosomal properties, yet no clinical studies have been performed. METHODS: We conducted a randomized, exploratory open-label trial to assess the efficacy and safety of mefloquine (25 mg/kg), artesunate (3 doses of 4 mg/kg), mefloquine-artesunate (3 doses of 100 mg artesunate plus 250 mg mefloquine), and praziquantel (40 mg/kg) against Schistosoma haematobium. The effects on Schistosoma mansoni, malaria parasitemia, soil-transmitted helminths, and intestinal protozoa were also determined. RESULTS: A total of 83 S. haematobium-infected schoolchildren were included in the study. Cure rates of mefloquine, artesunate, mefloquine-artesunate, and praziquantel against S. haematobium at day 26 after treatment were 21%, 25%, 61%, and 88%, respectively. Both mefloquine-artesunate and praziquantel resulted in egg reduction rates >95%. Significantly lower egg reduction rates were seen in the artesunate (85%) and mefloquine groups (74%). In children coinfected with S. mansoni, praziquantel and mefloquine-artesunate, but not mefloquine and artesunate alone, resulted in high cure rates and egg reduction rates. Mefloquine, artesunate, and mefloquine-artesunate completely cured infections due to Plasmodium falciparum. No effects were found against soil-transmitted helminths and intestinal protozoa. Abdominal pain was the most frequent adverse event, with a higher incidence among children treated with mefloquine (89%), mefloquine-artesunate (83%), and artesunate (60%) than among children treated with praziquantel (46%). CONCLUSIONS: The high efficacy of mefloquine-artesunate against S. haematobium warrants further investigation. Individuals coinfected with Plasmodium and Schistosoma who were treated with a mefloquine-artesunate combination against malaria might have a dual benefit: clearance of malaria parasitemia and reduction of schistosomiasis-related morbidity. CLINICAL TRIALS REGISTRATION: Current Controlled Trials identifier: ISRCTN06498763.

1 Comparative analyses of diversity variation among and between regions allow testing of alternative explanatory models and ideas. Here, we explore the relationships between the tree α-diversity of small rain forest plots in Africa and in Amazonia and climatic variables, to test the explanatory power of climate and the consistency of relationships between the two continents. 2 Our analysis included 1003 African plots and 512 Amazonian plots. All are located in old-growth primary non-flooded forest under 900 m altitude. Tree α-diversity is estimated using Fisher's alpha calculated for trees with diameter at breast height ≥ 10 cm. Mean diversity values are lower in Africa by a factor of two. 3 Climate-diversity analyses are based on data aggregated for grid cells of 2.5 × 2.5 km. The highest Fisher's alpha values are found in Amazonian forests with no climatic analogue in our African data set. When the analysis is restricted to pixels of directly comparable climate, the mean diversity of African forests is still much lower than that in Amazonia. Only in regions of low mean annual rainfall and temperature is mean diversity in African forests comparable with, or superior to, the diversity in Amazonia. 4 The climatic variables best correlated with the tree α-diversity are largely different in the African and Amazonian data, or correlate with African and Amazonian diversity in opposite directions. 5 These differences in the relationship between local/landscape-scale α-diversity and climate variables between the two continents point to the possible significance of an array of factors including: macro-scale climate differences between the two regions, overall size of the respective species pools, past climate variation, other forms of long-term and short-term environmental variation, and edaphics. We speculate that the lower α-diversity of African lowland rain forests reported here may be in part a function of the smaller regional species pool of tree species adapted to warm, wet conditions. 6 Our results point to the importance of controlling for variation in plot size and for gross differences in regional climates when undertaking comparative analyses between regions of how local diversity of forest varies in relation to other putative controlling factors.

In hermaphrodites, traits that influence the selfing rate can coevolve with inbreeding depression, leading to the emergence of evolutionary syndromes. Theory predicts a negative correlation between inbreeding depression and selfing rate across species. This prediction has only been examined and validated in vascular plants. Furthermore, selfing rates are often influenced by environmental conditions (e.g., lack of mates or pollinators), and species are predicted to evolve mechanisms to buffer this variation. We extend previous studies of mating-system syndromes in two ways. First, we assembled a new dataset on Basommatophoran snails (17 species, including new data on 12 species). Second, we measured how species responded to variation in mate availability. Specifically, we quantified the waiting time before selfing (i.e., how long the onset of reproduction is delayed in the absence of mates). Selfing rates were negatively correlated with both inbreeding depression and the waiting time. Species with stronger inbreeding depression exhibited longer waiting times. These patterns obtained on Basommatophorans still hold when including eight other hermaphroditic animals. Our results support the hypothesis that selection drives the evolution of mating-system syndromes in animals. The reaction norm of selfing rates to mate availability is a key target of natural selection in this context.

The biogeographic history of the African rain forests has been contentious. Phylogeography, the study of the geographic distribution of genetic lineages within species, can highlight the signatures of historical events affecting the demography and distribution of species (i.e. population fragmentation or size changes, range expansion/contraction) and, thereby, the ecosystems they belong to. The accumulation of recent data for African rain forests now enables a first biogeographic synthesis for the region. In this review, we explain which phylogeographic patterns are expected under different scenarios of past demographic change, and we give an overview of the patterns detected in African rain forest trees to discuss whether they support alternative hypotheses regarding the history of the African rain forest cover. The major genetic discontinuities in the region support the role of refugia during climatic oscillations, though not necessarily following the classically proposed scenarios. We identify in particular a genetic split between the North and the South of the Lower Guinean region. Finally we provide some perspectives for future study.

PURPOSE: Drug metabolism and pharmacokinetics (DMPK) assessment has come to occupy a place of interest during the early stages of drug discovery today. The use of computer modelling to predict the DMPK and toxicity properties of a natural product library derived from medicinal plants from Central Africa (named ConMedNP). Material from some of the plant sources are currently employed in African Traditional Medicine. METHODS: Computer-based methods are slowly gaining ground in this area and are often used as preliminary criteria for the elimination of compounds likely to present uninteresting pharmacokinetic profiles and unacceptable levels of toxicity from the list of potential drug candidates, hence cutting down the cost of discovery of a drug. In the present study, we present an in silico assessment of the DMPK and toxicity profile of a natural product library containing ~3,200 compounds, derived from 379 species of medicinal plants from 10 countries in the Congo Basin forests and savannas, which have been published in the literature. In this analysis, we have used 46 computed physico-chemical properties or molecular descriptors to predict the absorption, distribution, metabolism and elimination and toxicity (ADMET) of the compounds. RESULTS: This survey demonstrated that about 45% of the compounds within the ConMedNP compound library are compliant, having properties which fall within the range of ADME properties of 95% of currently known drugs, while about 69% of the compounds have ≤ 2 violations. Moreover, about 73% of the compounds within the corresponding "drug-like" subset showed compliance. CONCLUSIONS: In addition to the verified levels of "drug-likeness", diversity and the wide range of measured biological activities, the compounds from medicinal plants in Central Africa show interesting DMPK profiles and hence could represent an important starting point for hit/lead discovery.