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Fitness restoration of a genetically tractable Enterococcus faecalis V583 derivative to study decoration-related phenotypes of the enterococcal polysaccharide antigen
No full textCommensal and generally harmless in healthy individuals, Enterococcus faecalis causes opportunistic infections in immunocompromised patients. Plasmid-cured E. faecalis strain VE14089, derived from sequenced reference strain V583, is widely used for functional studies due to its improved genetic amenability. Although strain VE14089 has no major DNA rearrangements, with the exception of an ∼20-kb integrated region of pTEF1 plasmid, the strain presented significant growth differences from the V583 reference strain of our collection (renamed VE14002). In the present study, genome sequencing of strain VE14089 identified additional point mutations. Excision of the integrated pTEF1 plasmid region and sequential restoration of wild-type alleles showing nonsilent mutations were performed to obtain the VE18379 reference-derivative strain. Recovery of the growth ability of the restored VE18379 strain at a level similar to that seen with the reference strain points to GreA and Spx as bacterial fitness determinants. Virulence potential in Galleria mellonella and intestinal colonization in mouse demonstrated host adaptation of the VE18379 strain equivalent to VE14002 host adaptation. We further demonstrated that deletion of the 16.8-kb variable region of the epa locus recapitulates the key role of Epa decoration in host adaptation, providing a genetic system to study the role of specific epa-variable regions in host adaptation independently of other genetic variations.IMPORTANCE E. faecalis strain VE14089 was derived from V583 cured of its plasmids. Although VE14089 had no major DNA rearrangements, it presented significant growth and host adaptation differences from the reference strain V583 of our collection. To construct a strain with better fitness, we sequenced the genome of VE14089, identified single nucleotide polymorphisms (SNPs), and repaired the genes that could account for these changes. Using this reference-derivative strain, we provide a novel genetic system to understand the role of the variable region of epa in the enterococcal lifestyle
Tree diversity drives associational resistance to herbivory at both forest edge and interior
No full textTree diversity is increasingly acknowledged as an important driver of insect herbivory. However, there is still a debate about the direction of associational effects that can range from associational resistance (i.e., less damage in mixed stands than in monocultures) to the opposite, associational susceptibility. Discrepancies among published studies may be due to the overlooked effect of spatially dependent processes such as tree location within forests. We addressed this issue by measuring crown defoliation and leaf damage made by different guilds of insect herbivores on oaks growing among conspecific versus heterospecific neighbors at forest edges versus interior, in two closed sites in SW France forests. Overall, oaks were significantly less defoliated among heterospecific neighbors (i.e., associational resistance), at both forest edge and interior. At the leaf level, guild diversity and leaf miner herbivory significantly increased with tree diversity regardless of oak location within stands. Other guilds showed no clear response to tree diversity or oak location. We showed that herbivore response to tree diversity varied among insect feeding guilds but not between forest edges and interior, with inconsistent patterns between sites. Importantly, we show that oaks were more defoliated in pure oak plots than in mixed plots at both edge and forest interior and that, on average, defoliation decreased with increasing tree diversity from one to seven species. We conclude that edge conditions could be interacting with tree diversity to regulate insect defoliation, but future investigations are needed to integrate them into the management of temperate forests, notably by better understanding the role of the landscape context
Molecular analysis indicates high levels of carabid weed seed consumption in cereal fields across Central Europe
No full textCarabid beetles are abundant in temperate agroecosystems and can play a pivotal role as biocontrol agents. While there is good knowledge regarding their effects on invertebrate pests in some systems, comparably little is known on the rate of seed feeding under field conditions. Molecular approaches are ideally suited for investigating carabid feeding interactions; to date, however, they have only been applied to animal prey. We sampled adult carabid beetles in organic cereal fields in three regions along a Central European transect. Regurgitates from populations of the three most common species, Poecilus cupreus, Pseudoophonus rufipes and Pterostichus melanarius, were screened for plant DNA, cereal aphids, collembolans and earthworms. The frequency of carabid individuals positive for plant DNA was high (>70%) and independent of carabid species, sex, region and the time point of sampling. Detections for non-pest and pest prey were comparably lower, with 21.6% for collembolans, 18.1% for earthworms and 4.2% for aphids, respectively. Despite the prolonged detection period of plant DNA in carabid guts, as compared to animal prey, these first results suggest that weed seeds form an important part of the adult carabid diet. It would also lend support to the hypothesis that seed-feeding carabids are biocontrol agents of weeds, with effects of regulation on the weed seedbank that depend on behavioural and contextual factors including carabid species preferences for weed seed species, their life stage and tillage practices
Characterization of rat glutathione transferases in olfactory epithelium and mucus
No full textThe olfactory epithelium is continuously exposed to exogenous chemicals, including odorants. During the past decade, the enzymes surrounding the olfactory receptors have been shown to make an important contribution to the process of olfaction. Mammalian xenobiotic metabolizing enzymes, such as cytochrome P450, esterases and glutathione transferases (GSTs), have been shown to participate in odorant clearance from the olfactory receptor environment, consequently contributing to the maintenance of sensitivity toward odorants. GSTs have previously been shown to be involved in numerous physiological processes, including detoxification, steroid hormone biosynthesis, and amino acid catabolism. These enzymes ensure either the capture or the glutathione conjugation of a large number of ligands. Using a multi-technique approach (proteomic, immunocytochemistry and activity assays), our results indicate that GSTs play an important role in the rat olfactory process. First, proteomic analysis demonstrated the presence of different putative odorant metabolizing enzymes, including different GSTs, in the rat nasal mucus. Second, GST expression was investigated in situ in rat olfactory tissues using immunohistochemical methods. Third, the activity of the main GST (GSTM2) odorant was studied with in vitro experiments. Recombinant GSTM2 was used to screen a set of odorants and characterize the nature of its interaction with the odorants. Our results support a significant role of GSTs in the modulation of odorant availability for receptors in the peripheral olfactory process
Sugary drink consumption and risk of cancer: results from NutriNet-Santé prospective cohort
No full textOBJECTIVE
To assess the associations between the consumption of sugary drinks (such as sugar sweetened beverages and 100% fruit juices), artificially sweetened beverages, and the risk of cancer. DESIGN Population based prospective cohort study.
SETTING AND PARTICIPANTS
Overall, 101 257 participants aged 18 and over (mean age 42.2, SD 14.4; median follow-up time 5.1 years) from the French NutriNet-Sante cohort (2009-2017) were included. Consumptions of sugary drinks and artificially sweetened beverages were assessed by using repeated 24 hour dietary records, which were designed to register participants' usual consumption for 3300 different food and beverage items.
MAIN OUTCOME MEASURES
Prospective associations between beverage consumption and the risk of overall, breast, prostate, and colorectal cancer were assessed by multi-adjusted Fine and Gray hazard models, accounting for competing risks. Subdistribution hazard ratios were computed. RESULTS The consumption of sugary drinks was significantly associated with the risk of overall cancer (n=2193 cases, subdistribution hazard ratio for a 100mL/d increase 1.18, 95% confidence interval 1.10 to 1.27, P<0.0001) and breast cancer (693, 1.22, 1.07 to 1.39, P=0.004). The consumption of artificially sweetened beverages was not associated with the risk of cancer. In specific subanalyses, the consumption of 100% fruit juice was significantly associated with the risk of overall cancer (2193, 1.12, 1.03 to 1.23, P=0.007).
CONCLUSIONS
In this large prospective study, the consumption of sugary drinks was positively associated with the risk of overall cancer and breast cancer. 100% fruit juices were also positively associated with the risk of overall cancer. These results need replication in other large scale prospective studies. They suggest that sugary drinks, which are widely consumed in Western countries, might represent a modifiable risk factor for cancer prevention
Les jardins communs et leur importance pour la gestion forestière durable. Le pin pignon en exemple.
No full textLes jardins communs forestiers doivent être suivis, conservés, maintenus, voire étendus avec de nouvelles essences et doivent être bien renseignés et répertoriés dans les plans d’aménagements.Les résultats qui en sont issus doivent être diffusés et portés à la connaissance de tous, comme se proposent de le faire les projets en cours soutenus par le Ministère de l’Agriculture comme ESPERENSE , et MedForFutur, notamment. Les efforts de tous partenaires de la filière forestière française de recherche et développement pour se constituer en réseau (pour ce qui est des jardins communs, voir GEN4X et IN-Sylva et réfléchir à l’évolution de ces dispositifs pour prendre en compte les itinéraires sylvicoles, le potentiel offert par l’hybridation, la constitution de vergers à graines et îlots d’avenir, etc., vont aussi dans ce sens. Par ailleurs, les données issues de la gestion courante (suivis des coupes, régénérations et plantations par exemple) constituent aussi une ressource expérimentale d’une très grande richesse pour le choix des espèces et provenances, qui mérite d’être mieux tracée, archivée, valorisée (sommier électronique par exemple) et venir compléter les dispositifs de recherche classiques voir Fady et Scotti 2018 (Forêt Entreprise 240) et le blog
Les préférences pour le gras ne sont pas innées ! https://intranet.inra.fr/alimh/Vie-scientifique/Faits-marquants/FM2018
No full textLes lipides sont indispensables au début de la vie pour un développement optimal, notamment cérébral. Aussi, il est recommandé d’ajouter des matières grasses dans les aliments offerts aux jeunes enfants, dès le début de la diversification alimentaire. L’étude OPALINE a permis de montrer que l’appréciation pour le gras (présenté seul) évolue de l’indifférence au rejet entre 3 et 20 mois. Chez l’adulte, le gras est un déterminant majeur de l’acceptabilité des aliments. Pourtant, l’effet de l’ajout de matières grasses sur l’acceptabilité des aliments n’a jamais été exploré chez le nourrisson. L’objectif principal de cette étude était de comprendre si l’addition de différentes matières grasses (d’origine végétale ou animale) dans une purée de légume modifie son acceptabilité par le nourrisson au début de la diversification alimentaire. De plus, nous savons que le lait maternel et les préparations pour nourrissons ont des compositions lipidiques différentes. Cette étude a également permis d’évaluer si les réactions des nourrissons pouvaient être différentes en fonction du type de matières grasses auxquelles ils avaient été exposés dans les premiers mois de vie, selon le mode d’alimentation lactée reçu. Vingt-six nourrissons de 5 mois ont participé à l’étude durant le 1er mois de diversification alimentaire. La moitié d’entre eux avait été allaitée (5 semaines au minimum) et l’autre moitié nourrie avec des préparations pour nourrisson contenant uniquement des huiles végétales. Trois purées de brocoli leur ont été proposées : une sans matière grasse ajoutée, une contenant 7% d’un mélange d’huiles de colza et de tournesol et une autre apportant 7% de matières grasses laitières. Leur consommation (quantité consommée ad libitum) et leur appréciation (évaluée par leur mère) ont été enregistrées. Enfin, la salive des enfants a été collectée pour quantifier certains composés en lien avec l’acceptabilité du gras et la digestion lipidique. Dans cette étude, au début de la diversification alimentaire, l’ajout de matières grasses, qu’elles soient d’origine végétale ou laitière, n’a pas eu d’impact sur l’acceptabilité de purées de légume par les nourrissons. Les différences de quantités consommées observées entre nourrissons ne semblent être liées ni à leur exposition précoce aux matières grasses dans le lait, ni à des différences de composition salivaire.[br/]
Références :[br/]
- Acceptance of added fat to fi rst complementary feeding purees: An exploration of fat type, feeding history and saliva composition. Schwartz et al. Appetite. doi:10.1016/j.appet.2018.08.007[br/]
Partenaires : CSGA, GENIAL[br/
L’autonomie entre marché, rapport à la nature et production de soi : Approche sociologique des pratiques apicoles
No full textDepuis les années 1990, l’apiculture traverse une crise importante caractérisée par la mortalité accrue des colonies d’abeilles. Le maintien et le renouvellement du cheptel sont, dès lors, une préoccupation centrale pour les apiculteurs, quel que soit leur statut (amateur, double actif, professionnel). On s’emploiera à montrer que les techniques de renouvellement des colonies sont indissociables des objectifs poursuivis, des conceptions de l’apiculture, mais également d’un ensemble de contraintes (environnement, maladies, aléas climatiques, maîtrise technique, etc.) et témoignent de la recherche d’autonomie. Cette dernière étant envisagée comme moyen de réduire sa dépendance vis-à-vis de l’extérieur, mais aussi dans la perspective de Gorz, à savoir la liberté créatrice du sujet.Since the 1990s, beekeeping has been going through a major crisis characterized by increased mortality of bee colonies. The maintenance and renewal of livestock is therefore a central concern for beekeepers, whatever their status (enthousiast, multi-active, professional). We will try to show that colony renewal techniques are inseparable from the objectives pursued, from the conceptions of beekeeping, but also from a set of constraints (environment, diseases, climat change, technical control, etc.) and testify to the search for autonomy. The latter is envisaged as a means of reducing its dependence on the outside world but also from Gorz’s perspective, namely the creative freedom of the subject
Agroecology: Fostering improved access to land and natural resources
No full textThis presentation discusses the experience of Gora Ndiaye, President of the Pan African Association of Gardens and the Ecological and Organic Agriculture Platform for Senegal and how an integrated agroforestry, agroecology and community supported agriculture can regenerate depleted soils and create incentives for youths to enter farming.
The Agro-Ecological Farm School in Kaydara was established to address the challenges of villages being emptied of their youth, who move to the city or foreign countries. Young people no longer know how to live on their land where the soil is impoverished by monoculture conducted for decades and consequent erosion. The farmers are selling their land. Young people who want to stay in the village will soon be ‘landless’. The farm is located in the Fatick region, 150 km south of Dakar. It opened its doors in 2007 to welcome the first candidates for internship training. The action of the farm is to train farmers, young and old, women and men, in agroecological practices of diverse and complementary activities taking into account the necessity to restore soil fertility, protect the environment, and manage water. The registration criterion for a candidate to training was namely the ownership of at least one hectare of land. However this was not applicable at the opening of the training center. In order to resolve the case of young people without land ‘motivated’ by agroecology, land was acquired and allocated to those few young people at the start. The process has evolved since 2007 and gradually strategy has evolved: several mayors are now working with them to anchor agroecology in their land. Twenty young people from one same municipality were trained, and granted their 20 hectares of land with 80 hectares reserved by the Mayor council for future candidates. In another municipality 3 hectares were planned for the installation of 12 young people. In Fimela, where the farm is situated, local authorities have invested in the villages to explain the staffing approach of a hectare of land each young candidate following the training, so 20 hectares have been mobilized for 20 young people.
The engagement with municipalities serves to accompany the youth as they develop their farms to help also contribute to reforestation of the commons: 10,000 coconut trees have been planted in 5 years. The choice of coconut is due to environmental and economic reasons: the coconut tree’s speed of growth, the shade it provides to understory plants, the sustainable production of the coconut’s economic value by use of all its parts (nuts, leaves, trunk), the brake it presents to marine erosion, its fibrous roots, its majestic beauty. The engagement with municipalities also supports women in the production of reproducible seeds. Young farmers are in internship for a period of 9 months to 2 years. During their training they are provided different capital necessary for their installation: » Land capital; » The vegetable capital: fruit trees (mainly coconut trees), forest trees, forage; » The wildlife capital: poultry, rabbits, or donkeys. According to the choice of young farmers; » The seed capital; » The capital of agro-ecological knowledge and technological knowledge; » Financial capital consists of the sales revenue of their productions (2/3 for students, 1/3 for the Farm School). They design their personal project for their farm and submit it to the end of their training period. This project was highlighted for its pertinence and consistence with the principles and objectives of agroecology as it contributes to promote youth employment and prevent rural depopulation, ensure food security or food sovereignty of families, improve living conditions and offer prospects, fight against desertification, land degradation and salinization, restore soil fertility and preserve biodiversity