Crop diversity as an adaptation strategy to climate change in West Africa. [P152]

In Sub-Saharan Africa, climate fluctuation is believed to increase and smallholder's rainfed agriculture will be particularly challenged. This region is a crop domestication and diversity center for local crops, among which fonio, pearl millet and sorghum. A large amount of crop diversity is maintained by family farmers. This diversity is a basic fuel to allow future adaptation. In this presentation, we illustrate how this extraordinary genetic diversity mitigates the actual impacts of climate change in different crops. We will further analyze what biological mechanisms are involved (local adaptation, selection, gene flow...). We will illustrate the particular role of fonio ( Digitaria exilis, Stapf), a neglected and underutilized crop, in Western Africa agro - ecosystems. Our presentation shows that crops and landraces diversities are key factors for agriculture adaptation, and consequently that this diversity should be managed and conserved to allow local adaptation of agriculture. (Texte intégral

Geometric optimization of a blood pump impeller using the Taguchi method: CFD analysis and experimental evaluation

Rotodynamic Left Ventricular Assist Devices (LVADs) are critical in managing severe heart failure by providing mechanical circulatory support. Improving these blood pumps' efficiency is crucial for both lowering the device's energy consumption and enhancing patient comfort. In this study, the efficiency of a reference centrifugal blood pump was improved through geometric optimization and validated using computational fluid dynamics (CFD) simulations and experiments. The number of blades, inlet width, outlet width, inlet angle, and outlet angle are among the important impeller parameters that were optimized at three different levels. The orthogonal array of the Taguchi design method was used to reduce the 243 possible configurations from the full-factorial experimental design to 27 trial tests. Analysis of Variance (ANOVA) was used to determine the optimal geometric parameters, which led to maximum efficiency after S/N ratios were analyzed using MINITAB-18 software. The performance of the optimized pump was evaluated via CFD at 3300, 3150, and 3450 pump rotation speeds, resulting in a 21% increase in hydraulic efficiency at the design point (5 ​L/min, 3300 ​rpm, and 128.515 ​mm-Hg). Furthermore, experimental results demonstrated reduced power consumption for the optimized pump compared to the reference pump. This study highlights the potential of geometric optimization in advancing the performance of rotodynamic LVADs

Identification of Catechin as One of the Flavonoids from Combretum albiflorum Bark Extract That Reduces the Production of Quorum-Sensing-Controlled Virulence Factors in Pseudomonas aeruginosa PAO1 ▿

Quorum-sensing (QS) regulates the production of key virulence factors in Pseudomonas aeruginosa and other important pathogenic bacteria. In this report, extracts of leaves and bark of Combretum albiflorum (Tul.) Jongkind (Combretaceae) were found to quench the production of QS-dependent factors in P. aeruginosa PAO1. Chromatographic fractionation of the crude active extract generated several active fractions containing flavonoids, as shown by their typical spectral features. Purification and structural characterization of one of the active compounds led to the identification of the flavan-3-ol catechin [(2R,3S)-2-(3,4-dihydroxyphenyl)-3,4-dihydro-1(2H)-benzopyran-3,5,7-triol]. The identity of catechin as one of the active molecules was confirmed by comparing the high-pressure liquid chromatography profiles and the mass spectrometry spectra obtained for a catechin standard and for the active C. albiflorum fraction. Moreover, standard catechin had a significant negative effect on pyocyanin and elastase productions and biofilm formation, as well as on the expression of the QS-regulated genes lasB and rhlA and of the key QS regulatory genes lasI, lasR, rhlI, and rhlR. The use of RhlR- and LasR-based biosensors indicated that catechin might interfere with the perception of the QS signal N-butanoyl-l-homoserine lactone by RhlR, thereby leading to a reduction of the production of QS factors. Hence, catechin, along with other flavonoids produced by higher plants, might constitute a first line of defense against pathogenic attacks by affecting QS mechanisms and thereby virulence factor production

High selfing rate inferred for white fonio [Digitaria exilis (Kippist.) Stapf] reproductive system opens up opportunities for breeding programs

International audienceIn a context of the global major changes, it is mandatory to enlarge the range of crops supporting food security and pay great attention to neglected and underutilized species. However, basic knowledge of the biology of many neglected and underutilized species is still lacking to increase their yields. In this study, the mating system of white fonio [Digitaria exilis (Kippist.) Stapf], a West African minor and promising cereal, is assessed. Progenies arrays from both homozygous and heterozygous mothers were genotyped with microsatellites markers. The rate of genotyping errors in the experiments was assessed and a likelihood framework was used to determine the probability of different mating systems: outcrossing, self-fertilization and apomixis. The results suggested that white fonio has a highly selfing reproductive system with a possible outcrossing rate of 1.7%. Understanding the reproduction system of white fonio opens up opportunities for more effective breeding programs and a wider use of this cereal for food security improvement

Shifting Patterns of Influenza Circulation during the COVID-19 Pandemic, Senegal

Historically low levels of seasonal influenza circulation were reported during the first years of the COVID-19 pandemic and were mainly attributed to implementation of nonpharmaceutical interventions. In tropical regions, influenza’s seasonality differs largely, and data on this topic are scarce. We analyzed data from Senegal’s sentinel syndromic surveillance network before and after the start of the COVID-19 pandemic to assess changes in influenza circulation. We found that influenza shows year-round circulation in Senegal and has 2 distinct epidemic peaks: during January–March and during the rainy season in August–October. During 2021–2022, the expected January–March influenza peak completely disappeared, corresponding to periods of active SARS-CoV-2 circulation. We noted an unexpected influenza epidemic peak during May–July 2022. The observed reciprocal circulation of SARS-CoV-2 and influenza suggests that factors such as viral interference might be at play and should be further investigated in tropical settings

The flavanone naringenin reduces the production of quorum sensing-controlled virulence factors in Pseudomonas aeruginosa PAO1

Preliminary screening of the Malagasy plant Combretum albiflorum for compounds attenuating the production of quorum sensing (QS)-controlled virulence factors in bacteria led to the identification of active fractions containing flavonoids. In the present study, several flavonoids belonging to the flavone, flavanone, flavonol and chalcone structural groups were screened for their capacity to reduce the production of QS-controlled factors in the opportunistic pathogen Pseudomonas aeruginosa (strain PAO1). Flavanones (i.e. naringenin, eriodictyol and taxifolin) significantly reduced the production of pyocyanin and elastase in P. aeruginosa without affecting bacterial growth. Consistently, naringenin and taxifolin reduced the expression of several QS-controlled genes (i.e. lasI, lasR, rhlI, rhlR, lasA, lasB, phzA1 and rhlA) in P. aeruginosa PAO1. Naringenin also dramatically reduced the production of the acylhomoserine lactones N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12-HSL) and N-butanoyl-l-homoserine lactone (C4-HSL), which is driven by the lasI and rhlI gene products, respectively. In addition, using mutant strains deficient for autoinduction (ΔlasI and ΔrhlI) and LasR- and RhlR-based biosensors, it was shown that QS inhibition by naringenin not only is the consequence of a reduced production of autoinduction compounds but also results from a defect in the proper functioning of the RlhR-C4-HSL complex. Widely distributed in the plant kingdom, flavonoids are known for their numerous and determinant roles in plant physiology, plant development and in the success of plant-rhizobia interactions, but, as shown here, some of them also have a role as inhibitors of the virulence of pathogenic bacteria by interfering with QS mechanisms.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Hydroxychloroquine and Azithromycin Treatment of Hospitalized Patients Infected with SARS-CoV-2 in Senegal from March to October 2020

As of today, little data is available on COVID-19 in African countries, where the case management relied mainly on a treatment by association between hydroxychloroquine (HCQ) and azithromycin (AZM). This study aimed to understand the main clinical outcomes of COVID-19 hospitalized patients in Senegal from March to October 20202. We described the clinical characteristics of patients and analysed clinical status (alive and discharged versus hospitalized or died) at 15 days after Isolation and Treatment Centres (ITC) admission among adult patients who received HCQ plus AZM and those who did not receive this combination. A total of 926 patients were included in this analysis. Six hundred seventy-four (674) (72.8%) patients received a combination of HCQ and AZM. Results showed that the proportion of patient discharge at D15 was significantly higher for patients receiving HCQ plus AZM (OR: 1.63, IC 95% (1.09–2.43)). Factors associated with a lower proportion of patients discharged alive were: age ≥ 60 years (OR: 0.55, IC 95% (0.36–0.83)), having of at least one pre-existing disorder (OR: 0.61, IC 95% (0.42–0.90)), and a high clinical risk at admission following NEWS score (OR: 0.49, IC 95% (0.28–0.83)). Few side effects were reported including 2 cases of cardiac rhythmic disorders in the HCQ and AZM group versus 13 in without HCQ + AZM. An improvement of clinical status at 15 days was found for patients exposed to HCQ plus AZM combination.</jats:p