After initial declines, in mid-2020 a resurgence in transmission of novel coronavirus disease (COVID-19) occurred in the United States and Europe. As efforts to control COVID-19 disease are ...reintensified, understanding the age demographics driving transmission and how these affect the loosening of interventions is crucial. We analyze aggregated, age-specific mobility trends from more than 10 million individuals in the United States and link these mechanistically to age-specific COVID-19 mortality data. We estimate that as of October 2020, individuals aged 20 to 49 are the only age groups sustaining resurgent SARS-CoV-2 transmission with reproduction numbers well above one and that at least 65 of 100 COVID-19 infections originate from individuals aged 20 to 49 in the United States. Targeting interventions-including transmission-blocking vaccines-to adults aged 20 to 49 is an important consideration in halting resurgent epidemics and preventing COVID-19-attributable deaths.
Competition between glucose and lactate as oxidative energy substrates was investigated in both primary cultures of astrocytes and neurons using physiological concentrations (1.1 mm for each). ...Glucose metabolism was distinguished from lactate metabolism by using alternatively labelled substrates in the medium (1‐13Cglucose + lactate or glucose + 3‐13Clactate). After 4 h of incubation, 1H and 13C‐NMR spectra were realized on perchloric acid extracts of both cells and culture media. For astrocytic cultures, spectra showed that amino acids (glutamine and alanine) were more labelled in the glucose‐labelled condition, indicating that glucose is a better substrate to support oxidative metabolism in these cells. The opposite was observed on spectra from neuronal cultures, glutamate being much more labelled in the lactate‐labelled condition, confirming that neurons consume lactate preferentially as an oxidative energy substrate. Analysis of glutamine and glutamate peaks (singlets or multiplets) also suggests that astrocytes have a less active oxidative metabolism than neurons. In contrast, they exhibit a stronger glycolytic metabolism than neurons as indicated by their high lactate production yield. Using a mathematical model, we have estimated the relative contribution of exogenous glucose and lactate to neuronal oxidative metabolism. Under the aforementioned conditions, it represents 25% for glucose and 75% for lactate. Altogether, these results obtained on separate astrocytic and neuronal cultures support the idea that lactate, predominantly produced by astrocytes, is used as a supplementary fuel by neurons in vivo already under resting physiological conditions.
Climate changes will have an impact on food production and will require costly adaptive responses. Adapting to a changing environment will be particularly challenging in sub-Saharan Africa where ...climate change is expected to have a major impact. However, one important phenomenon that is often overlooked and is poorly documented is the ability of agro-systems to rapidly adapt to environmental variations. Such an adaptation could proceed by the adoption of new varieties or by the adaptation of varieties to a changing environment. In this study, we analyzed these two processes in one of the driest agro-ecosystems in Africa, the Sahel. We performed a detailed study in Niger where pearl millet is the main crop and covers 65% of the cultivated area. To assess how the agro-system is responding to recent recurrent drought, we analyzed samples of pearl millet landraces collected in the same villages in 1976 and 2003 throughout the entire cultivated area of Niger. We studied phenological and morphological differences in the 1976 and 2003 collections by comparing them over three cropping seasons in a common garden experiment. We found no major changes in the main cultivated varieties or in their genetic diversity. However, we observed a significant shift in adaptive traits. Compared to the 1976 samples, samples collected in 2003 displayed a shorter lifecycle, and a reduction in plant and spike size. We also found that an early flowering allele at the PHYC locus increased in frequency between 1976 and 2003. The increase exceeded the effect of drift and sampling, suggesting a direct effect of selection for earliness on this gene. We conclude that recurrent drought can lead to selection for earlier flowering in a major Sahelian crop. Surprisingly, these results suggest that diffusion of crop varieties is not the main driver of short term adaptation to climatic variation.
Identifying the molecular bases of adaptation is a key issue in evolutionary biology. Genome scan is an efficient approach for identifying important molecular variation involved in adaptation. ...Association mapping also offers an opportunity to gain insight into genotype–phenotype relationships. Using these two approaches coupled with environmental data should help to come up with a refined picture of the evolutionary process underlying adaptation. In this study, we first conducted a selection scan analysis on a transcription factor gene family. We focused on the MADS‐box gene family, a gene family which plays a crucial role in vegetative and flower development. Twenty‐one pearl millet populations were sampled along an environmental gradient in West Africa. We identified one gene, i.e. PgMADS11, using Bayesian analysis to detect selection signatures. Polymorphism at this gene was also associated with flowering time variation in an association mapping framework. Finally, we found that PgMADS11 allele frequencies were closely associated with annual rainfall. Overall, we determined an efficient way to detect functional polymorphisms associated with climate variation in non‐model plants by combining genome scan and association mapping. These results should help monitor the impact of recent climatic changes on plant adaptation.
Abstracts Allinne, Clémentine; Amoukou, Adamou I.; Balma, Didier ...
Ressources génétiques des mils en Afrique de l'Ouest : diversité, conservation et valorisation,
10/2013
Journal Article
J.-P. Guengant and M. Banoin: “Pearl millet, demography and food security in Niger” Millet is the cereal best adapted to arid and semi-arid zones. It still constitutes, along with sorghum, the staple ...food of the diet of Sahelian populations, for whom it remains an uncontested plant of civilisation. However, with a demographic growth of over 3 percent a year, most Sahelian populations are today in a state of chronic food shortage. This is the case in Niger, where the trend in national cereal p...
Résumés Allinne, Clémentine; Amoukou, Adamou I.; Balma, Didier ...
Ressources génétiques des mils en Afrique de l'Ouest : diversité, conservation et valorisation,
10/2013
Journal Article
J.-P. Guengant, M. Banoin : « Mil, démographie et sécurité alimentaire au Niger » Le mil est la céréale la mieux adaptée aux zones semi-arides et arides. Il constitue toujours, avec le sorgho, la ...base de l’alimentation et la plante de civilisation incontournable des populations du Sahel. Cependant les populations sahéliennes, dont la croissance démographique dépasse les 3 % par an, sont déjà pour la plupart en situation d’insécurité alimentaire chronique. C’est le cas en particulier au Niger,...
Liste des auteurs Allinne, Clémentine; Amoukou, Adamou I.; Balma, Didier ...
Ressources génétiques des mils en Afrique de l'Ouest : diversité, conservation et valorisation,
10/2013
Journal Article
Clémentine Allinne, IRD, B.P. 11416 Niamey, Niger.clementine.allinne@ird.ne Adamou I. Amoukou, Faculté d’Agronomie, BP. 10960 - Niamey, NIGER.cresa@intnet.ne Didier Balma, Coordonnateur du Programme ...National de Ressources Phytogénétiques, Ministère des Enseignements Secondaire et Supérieur et de la Recherche Scientifique, 01 BP 476 Ouagadougou 01, Burkina Faso.g.ipgri@cgiar.org Jibril Bani, Faculté d’Agronomie, BP. 10960 - Niamey, NIGER.cresa@intnet.ne Maxime Banoin, Faculté d’Agronomie, BP. ...
Liste des participants Allinne, Clémentine; Amoukou, Adamou I.; Balma, Didier ...
Ressources génétiques des mils en Afrique de l'Ouest : diversité, conservation et valorisation,
10/2013
Journal Article
Autorités nigériennes : Monsieur le Ministre de l’Agriculture : représenté Monsieur le Directeur de l’Agriculture : représenté Monsieur le Directeur de la Recherche : représenté Monsieur le ...Coordonnateur du CRESA (UAM-Niamey) : Toudou Adam Représentant Monsieur le Doyen de la Faculté d’Agronomie Ambassade de France : Christophe Besacier (Ambassade de France : conseiller pour l’agriculture, SCAC) David Sadoulet (Conseiller auprès de Monsieur le Premier Ministre) Union européenne : Madame Marie...
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