Dynamique de la teneur en carbone et en azote des sols dans les systèmes d’exploitation du Ferlo : cas du CRZ de Dahra

Objectif : Cette étude, réalisée au Centre de Recherches Zootechniques (CRZ) de Dahra situé en Région sylvopastorale du Sénégal, a pour objectif d’apprécier l’évolution de la teneur en carbone, en azote et le stock de carbone du sol dans ses différents systèmes d’exploitation.Méthodologie et résultats : En 2011, des échantillons de sols (à 0-20 cm et 20 – 40 cm) ont été prélevés au niveau des mêmes sites que ceux qui ont fait l’objet d’analyse de sols en 1962, afin de déterminer la teneur en carbone et azote du sol. Le nombre d’échantillons est fonction de la superficie des différents types de sols rencontrés. L’utilisation de la cartographie nous a permis de déterminer le nombre d’échantillon prélevé sur chaque système d’exploitation. Au niveau du CRZ de Dahra, l’analyse des paramètres pédologiques (teneur en carbone, en azote et rapport C/N) de l’horizon 0-20 cm, n’a pas révélé de différence significative entre 1962 et 2011. Par contre, dans l’horizon 20-40 cm, seule la teneur en azote présente une hausse significative entre ces deux périodes. S’agissant des systèmes d’exploitation du CRZ de Dahra, l’analyse de la teneur en carbone, en azote et du rapport C/N de l’horizon 0-20 cm, n’a pas révélé de différence significative aussi bien pour l’année 1962 que celle de 2011. Au niveau de l’horizon 20-40 cm, parmi les paramètres étudiés, seul la teneur en carbone de 1962 présentait une différence significative (au seuil de 5%) entre les systèmes de cultures et les pâturages. Le stock de carbone du centre est en moyenne de 0,08±0,03 et 0,06±0,02 t/ha respectivement pour les horizons 0-20 et 20-40 cm. Celui-ci est plus important au niveau des gommiers et plus faibles dans les systèmes de culture et les pâturages.Conclusion et application des résultats : Cette étude a permis de montrer qu’au niveau du CRZ de Dahra à vocation essentiellement pastorale, le carbone et l’azote du sol, présente une certaine stabilité dans les différents systèmes d’exploitation. Toutefois, les gommiers présentent les teneurs en carbone et en azote du sol les plus importantes. Ces résultats peuvent servir de données d’entrée aux modèles de prévision de la séquestration du carbone et de l’azote du sol des écosystèmes sahéliens pastoraux, être valorisés en aménagement pastoral et agro-sylvopastoral en vue d’une meilleure préservation de l’environnement et de la gestion de la fertilité du sol.Mots clés : carbone, l'azote, le contenu, les sol

Optimal health investment with separable and non-separable preferences

UNU-MERIT Working Papers intend to disseminate preliminary results of research carried out at UNU-MERIT and MGSoG to stimulate discussion on the issues raised. Optimal health investment with separable and non-separable preferences

Real-time sequencing to decipher the molecular mechanism of resistance of a clinical pan-drug-resistant Acinetobacter baumannii isolate from Marseille, France.

We compare the whole-genome sequences of two multidrug-resistant clinical Acinetobacter baumannii isolates recovered in the same patient before (ABIsac_ColiS susceptible to colistin and rifampin only) and after (ABIsac_ColiR resistant to colistin and rifampin) treatment with colistin and rifampin. We decipher all the molecular mechanisms of antibiotic resistance, and we found mutations in the rpoB gene and in the PmrAB two-component system explaining resistance to rifampin and colistin in ABIsac_ColiR, respectively

Longitudinal changes in acylated versus unacylated ghrelin levels may be involved in the underlying mechanisms of the switch in nutritional phases in Prader-Willi syndrome

Introduction: Prader-Willi syndrome (PWS) is characterized by a switch from failure to thrive to excessive weight gain and hyperphagia in early childhood. An elevated, more unfavorable ratio between acylated and unacylated ghrelin (AG/UAG ratio) might play a role in the underlying mechanisms of this switch. We aimed to assess the evolution of the appetite-regulating hormones acylated ghrelin (AG) and unacylated ghrelin (UAG) and the AG/UAG ratio and their association with the change in eating behavior in children with PWS, compared to healthy age-matched controls. Methods: A longitudinal study was conducted in 134 children with PWS and 157 healthy controls, from the Netherlands, France, and Belgium. Levels of AG and UAG and the AG/UAG ratio were measured and nutritional phases as reported for PWS were scored. Results: The AG/UAG ratio was lower in the first years of life in PWS than in controls and started to increase from the age of 3 years, resulting in a high-normal AG/UAG ratio compared to controls. The AG levels remained stable during the different nutritional phases (p = 0.114), while the UAG levels decreased from 290 pg/mL in phase 1a to 137 pg/mL in phase 2b (p < 0.001). The AG/UAG ratio increased significantly from 0.81 in phase 2a to 1.24 in phase 2b (p = 0.012). Conclusions: The change from failure to thrive to excessive weight gain and hyperphagia in infants and children with PWS coincides with an increase in AG/UAG ratio. The increase in AG/UAG ratio occurred during phase 2a, thus before the onset of hyperphagia

Carbapenem- and colistin-resistant Enterobacterales in intensive care unit patients in Mediterranean countries, 2019

IntroductionThe colonization of patients by carbapenemase-producing Enterobacterales (CPE) has been associated with heightened mortality, especially in vulnerable individuals within intensive care units (ICUs). Our study aimed to comprehensively assess CPE prevalence among ICU patients across the Mediterranean region pre-COVID-19, conducting a multicenter prevalence study in the first quarter of 2019.MethodsWe collected clinical data and rectal or fecal samples from 256 ICU patients for CPE testing. Additionally, we performed whole-genome sequencing on 40 representative CPE strains to document their molecular characteristics.ResultsAmong the 256 patients, CPE was detected in 73 samples (28.5%), with prevalence varying from 3.3 to 69.0% across participating centers. We observed 13 colistin-resistant CPE strains, affecting three ICUs. Genetic analysis revealed highly diverse E. coli and K. pneumoniae strains, predominantly from international high-risk clones. Notably, blaOXA-48 and blaNDM-1 were the most prevalent carbapenemase genes. Molecular typing uncovered potential patient clusters in six centers. Significantly, longer hospital stays were associated with increased CPE carriage (p < 0.001). Nine centers across Morocco, Tunisia, Egypt, and Lebanon voluntarily participated.DiscussionOur study provides CPE prevalence in Mediterranean ICUs and reaffirms established CPE presence in this setting but also provides updates on the molecular diversity of CPE strains. These findings highlight the imperative of reinforcing infection control measures in the participating ICUs to curtail escalated mortality rates, and of strictly applying isolation measures around patients originating from the Mediterranean region when transferred to other healthcare institutions

ARG-ANNOT, a New Bioinformatic Tool To Discover Antibiotic Resistance Genes in Bacterial Genomes

ARG-ANNOT (Antibiotic Resistance Gene-ANNOTation) is a new bioinformatic tool that was created to detect existing and putative new antibiotic resistance (AR) genes in bacterial genomes. ARG-ANNOT uses a local BLAST program in Bio-Edit software that allows the user to analyze sequences without a Web interface. All AR genetic determinants were collected from published works and online resources; nucleotide and protein sequences were retrieved from the NCBI GenBank database. After building a database that includes 1,689 antibiotic resistance genes, the software was tested in a blind manner using 100 random sequences selected from the database to verify that the sensitivity and specificity were at 100% even when partial sequences were queried. Notably, BLAST analysis results obtained using the rmtF gene sequence (a new aminoglycoside-modifying enzyme gene sequence that is not included in the database) as a query revealed that the tool was able to link this sequence to short sequences (17 to 40 bp) found in other genes of the rmt family with significant E values. Finally, the analysis of 178 Acinetobacter baumannii and 20 Staphylococcus aureus genomes allowed the detection of a significantly higher number of AR genes than the Resfinder gene analyzer and 11 point mutations in target genes known to be associated with AR. The average time for the analysis of a genome was 3.35 ± 0.13 min. We have created a concise database for BLAST using a Bio-Edit interface that can detect AR genetic determinants in bacterial genomes and can rapidly and easily discover putative new AR genetic determinants

Biotyping of Multidrug-Resistant Klebsiella pneumoniae Clinical Isolates from France and Algeria Using MALDI- TOF MS

Abstract Background: Klebsiella pneumoniae is one of the most important pathogens responsible for nosocomial outbreaks worldwide. Epidemiological analyses are useful in determining the extent of an outbreak and in elucidating the sources and the spread of infections. The aim of this study was to investigate the epidemiological spread of K. pneumoniae strains using a MALDI-TOF MS approach

Emergence of the OXA-23 carbapenemase-encoding gene in multidrug-resistant Acinetobacter baumannii clinical isolates from the Principal Hospital of Dakar, Senegal

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