Response of native soil microbial functions to the controlled mycorrhization of an exotic tree legume, <Emphasis Type="Italic">Acacia holosericea</Emphasis> in a Sahelian ecosystem

Fifty years of overexploitation have disturbed most forests within Sahelian areas. Exotic fast growing trees (i.e., Australian Acacia species) have subsequently been introduced for soil improvement and fuelwood production purposes. Additionally, rhizobial or mycorrhizal symbioses have sometimes been favored by means of controlled inoculations to increase the performance of these exotic trees in such arid and semiarid zones. Large-scale anthropogenic introduction of exotic plants could also threaten the native biodiversity and ecosystem resilience. We carried out an experimental reforestation in Burkina Faso in order to study the effects of Acacia holosericea mycorrhizal inoculation on the soil nutrient content, microbial soil functionalities and mycorrhizal soil potential. Treatments consisted of uninoculated A. holosericea, preplanting fertilizer application and arbuscular mycorrhizal inoculation with Glomus intraradices. Our results showed that (i) arbuscular mycorrhizal (AM) inoculation and prefertilizer application significantly improved A. holosericea growth after 4 years of plantation and (ii) the introduction of A. holosericea trees significantly modified soil microbial functions. The results clearly showed that the use of exotic tree legume species should be directly responsible for important changes in soil microbiota with great disturbances in essential functions driven by microbial communities (e.g., catabolic diversity and C cycling, phosphatase activity and P availability). They also highlighted the importance of AM symbiosis in the functioning of soils and forest plantation performances. The AM effect on soil functions was significantly correlated with the enhanced mycorrhizal soil potential recorded in the AM inoculation treatment.     

Physiological and ultrastructural responses of sour orange (Citrus aurantium L.) clones to water stress

Water stress is a major abiotic constraint leading to serious crop losses. Recently, in the Mediterranean region, water stress has become markedly sensed, especially in Citrus orchards. This study investigated the physiological responses of local sour orange (Citrus aurantium L.) clones to severe water stress. Water stress was applied by withholding irrigation during weeks, followed by a rewatering phase during three months. Under water stress, sour orange clones decreased their stomatal conductance, net photosynthetic rate, and transpiration rate. On the contrary, biomass was stable, especially in the Kliaa clone. In addition, reduced leaf water potentials (-3 MPa) and water contents were measured in most of the clones, except Kliaa which kept the highest water potential (-2.5 MPa). After rewatering, all clones recovered except of the Ghars Mrad (GM) clone. Ultrastructural observations of leaf sections by transmission electron microscopy did not reveal marked alterations in the mesophyll cells and chloroplast structure of Kliaa in comparison to the sensitive clone GM, in which palisade parenchyma cells and chloroplasts were disorganized. This contrasting behavior was mainly attributed to genetic differences as attested by molecular analysis. This study highlighted GM as the drought-sensitive clone and Kliaa as the tolerant clone able to develop an avoidance strategy based on an efficient stomatal regulation. Although a high percentage of polyembryony characterizes C. aurantium and justifies its multiplication by seeds, heterogeneous water-stress responses could be observed within sour orange plants in young orchards.     

La dysfonction éréctile au Sénégal: Profil épidemiologique

Methodology

This was a transverse randomized survey of subjects over the age of 18 years. Subjects completed a self-administered questionnaire composed of two parts. The first part contained information on demographic characteristics, associated diseases, erectile dysfunction and associated sexual disorders and the second part was based on IIEF5. Two groups were identified: a group with erectile dysfunction (ED group) and another group without erectile dysfunction (No ED group). Differences between the two groups were considered to be statistically significant for p ≤ 0.05 on the Chi-square test.

Results

The global prevalence of erectile dysfunction was 26%. The prevalence by age-group revealed a progressive increase of ED with age from 11% between 20 and 30 years to 76% between 70 and 80 years. The rate of polygamous men was significantly higher in the group with ED (29.2%) compared to the group without ED (6.6%) (p < 0.0001) and the severity of ED increased in relation to the number of wives. Chronic alcoholism was significantly more frequent in the group with ED (p = 0.023). The frequency of ED increased with the duration of cigarette smoking from 11.9% for less than 5 years, 16.9% between 5 years and 10 years and 71.2% for more than 10 years. Some diseases (diabetes, hypertension and depression) were significantly more frequent in the group with ED. Analysis of the type of ED revealed that secondary erectile dysfunction was more frequent (95.6%) than primary erectile dysfunction (4.4%). Associated sexual disorders were significantly more frequent in the group with ED.     

The last African white giraffes live in farmers’ fields

The giraffe population (Giraffa camelopardalis) in Niger is the last representative of the peralta sub-species which lived throughout West Africa at the beginning of the twentieth century. Protected since the 1970s, giraffes cohabit with humans in cultivated landscapes. This may not have appeared to pose many problems in the past, but the relationship between farmers and giraffes has deteriorated with the expansion of cultivated land and that of the giraffe population, with reported cases of giraffes damaging crops. A survey was conducted in all the affected villages in the Kouré area to establish the nature, severity and distribution of the damage and to evaluate the local populations’ perception of the problem. Cowpeas are fed upon in the field at harvest time and in the granaries, as well as ripe mangoes, during the most critical period for giraffes’ nutrition. The vast majority of farmers interviewed consider giraffes to be rather a problem in spite of tourism revenues they can obtain from them. This opinion has individually little correlation with damage rate on crops or easy access to tourism revenues. The damage risk factors are first and foremost considered as uncontrollable by the farmers, even if technical protection measures could easily be put in place locally. The inter-relationships between the socio-economic context and the way the problem is perceived are discussed.     

Morphological and molecular analyses in Scleroderma species associated with some Caesalpinioid legumes, Dipterocarpaceae and Phyllanthaceae trees in southern Burkina Faso

A combination of morphotypes, polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) analyses and internal transcribed spacer (ITS) sequencing was used to investigate Scleroderma species that were collected from woodlands in Burkina Faso. We harvested 52 specimens from 20 sites during rainy seasons between 1997 and 2000. According to their morphological features, these specimens were initially characterised, and we then identified six species of Scleroderma. Two of the species were clearly determined as Scleroderma dictyosporum Pat. and S. verrucosum Pers. The four remaining species were characteristically described as (1) displaying big spores with spines up to 2 μm (Scleroderma sp1), (2) producing spores without ornamentation (Scleroderma sp2), (3) spores with very small spines (Scleroderma sp3) and (4) with yellow sporocarps and sub-spherical spores (Scleroderma sp4). The specimens were then analysed using PCR/RFLP of the intergenic regions of rDNA, ITS and IGS1 and ITS sequencing. The restriction fragments obtained with two endonucleases, HinfI and MboI on ITS and IGS1 regions, showed that some isolates of S. dictyosporum had the same patterns as isolates and basidiocarps of Scleroderma sp4 (IR265, IR408, SP4-2903). Isolates of Scleroderma sp3 (IR252) had common restriction fragments as isolates of S. verrucosum (IR500, IR600). Intraspecific differences were observed in the two previously determined species, as well as in Scleroderma sp2. The ITS sequencing and phylogenetic analyses showed that the ribotypes identified by PCR/RFLP within these species might be phylogenetic species. Combining these molecular results allowed regrouping the six morphological species in three sets of cryptic species: a first set with two species including S. dictyosporum Pat., a second set with four species, including both S. verrucosum Pers. and Scleroderma sp1 and a third set with two species, including Scleroderma sp2. These investigations and the combined morphological and molecular analyses used to sort out species paved the way for identifying larger populations of Scleroderma species in Burkina Faso and other tropical zones.     

Long-Term Potentiation in Isolated Dendritic Spines

Background

In brain, N-methyl-D-aspartate (NMDA) receptor (NMDAR) activation can induce long-lasting changes in synaptic α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor (AMPAR) levels. These changes are believed to underlie the expression of several forms of synaptic plasticity, including long-term potentiation (LTP). Such plasticity is generally believed to reflect the regulated trafficking of AMPARs within dendritic spines. However, recent work suggests that the movement of molecules and organelles between the spine and the adjacent dendritic shaft can critically influence synaptic plasticity. To determine whether such movement is strictly required for plasticity, we have developed a novel system to examine AMPAR trafficking in brain synaptosomes, consisting of isolated and apposed pre- and postsynaptic elements.

Methodology/Principal Findings

We report here that synaptosomes can undergo LTP-like plasticity in response to stimuli that mimic synaptic NMDAR activation. Indeed, KCl-evoked release of endogenous glutamate from presynaptic terminals, in the presence of the NMDAR co-agonist glycine, leads to a long-lasting increase in surface AMPAR levels, as measured by [³H]-AMPA binding; the increase is prevented by an NMDAR antagonist 2-amino-5-phosphonopentanoic acid (AP5). Importantly, we observe an increase in the levels of GluR1 and GluR2 AMPAR subunits in the postsynaptic density (PSD) fraction, without changes in total AMPAR levels, consistent with the trafficking of AMPARs from internal synaptosomal compartments into synaptic sites. This plasticity is reversible, as the application of AMPA after LTP depotentiates synaptosomes. Moreover, depotentiation requires proteasome-dependent protein degradation.

Conclusions/Significance

Together, the results indicate that the minimal machinery required for LTP is present and functions locally within isolated dendritic spines.     

Efficacy of Artesunate + Sulfamethoxypyrazine/Pyrimethamine versus Praziquantel in the Treatment of Schistosoma haematobium in Children

Background

This study was conducted to determine the efficacy of the antimalarial artemisinin-based combination therapy (ACT) artesunate +sulfamethoxypyrazine/pyrimethamine (As+SMP), administered in doses used for malaria, to treat Schistosoma haematobium in school aged children.

Methodology/Principal Findings

The study was conducted in Djalakorodji, a peri-urban area of Bamako, Mali, using a double blind setup in which As+SMP was compared with praziquantel (PZQ). Urine samples were examined for Schistosoma haematobium on days −1, 0, 28 and 29. Detection of haematuria, and haematological and biochemical exams were conducted on day 0 and day 28. Clinical exams were performed on days 0, 1, 2, and 28. A total of 800 children were included in the trial. The cure rate obtained without viability testing was 43.9% in the As+SMP group versus 53% in the PZQ group (Chi² = 6.44, p = 0.011). Egg reduction rates were 95.6% with PZQ in comparison with 92.8% with As+SMP, p = 0.096. The proportion of participants who experienced adverse events related to the medication was 0.5% (2/400) in As+SMP treated children compared to 2.3% (9/399) in the PZQ group (p = 0.033). Abdominal pain and vomiting were the most frequent adverse events in both treatment arms. All adverse events were categorized as mild.

Conclusions/Significance

The study demonstrates that PZQ was more effective than As+SMP for treating Schistosoma haematobium. However, the safety and tolerability profile of As+SMP was similar to that seen with PZQ. Our findings suggest that further investigations seem justifiable to determine the dose/efficacy/safety pattern of As+SMP in the treatment of Schistosoma infections.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00510159","term_id":"NCT00510159"}}NCT00510159 http://clinicaltrials.gov/ct2/show/NCT00510159