Assessing non-intended effects of farming practices on field margin vegetation with a functional approach

International audienceTo assess the unwanted side effects of farming practices on non-target plants, we used a nationwide survey of the vegetation of arable field margin strips. The vegetation was surveyed during two years (2013, 2014) in 430 field margins distributed over all agricultural regions of France. We used two complementary multivariate, trait-based approaches to examine how ten plant traits were related to ten environmental variables describing abiotic conditions, landscape factors, field margin management and in-field practices. Generalized additive mixed models were also developed to assess how the same environmental variables correlated with species richness, functional diversity and relative richness of agrotolerant versus hemerophobic species. Traits responded primarily to an environmental gradient of landscape diversity and field margin management. For instance, narrow field margin strips, frequent management and presence of a ditch favoured annual plants, small size at maturity and perennial plants, respectively. The second environmental gradient affecting plant traits was related to field size and intensity of in-field farming practices. On this gradient, fertilizer drift appeared to have a much stronger effect on plant trait composition of field margin strips than herbicide drift. The relationship between species richness, or functional diversity, and environment was consistent with the trait-based approach: the two former variables were negatively correlated with agriculture intensification (e.g. field size). However, this analysis also highlighted new covariates, such as a negative relationship between frequency of herbicide use and species richness. Some of the observed patterns seemed to be driven by differential responses of agrotolerant versus hemerophobic species, with the latter being more species-rich under organic than under conventional farming. Despite efforts to reduce nitrogen inputs since the 2000s, our results shows that N-fertilization still has significant non-intended effects on field margin vegetation. More generally, increasing the width of field margin strips, keeping or restoring semi-natural elements (ditches, hedges) in the field boundary, and lowering the number of management events may promote grassland plant species more typical of semi-natural habitats

Predation risk landscape modifies flying and red squirrel nest site occupancy independently of habitat amount

Habitat choice often entails trade-offs between food availability and predation risk. Understanding the distribution of individuals in space thus requires that both habitat characteristics and predation risk are considered simultaneously. Here, we studied the nest box use of two arboreal squirrels who share preferred habitat with their main predators. Nocturnal Ural owls (Strix uralensis) decreased occurrence of night-active flying squirrels (Pteromys volans) and diurnal goshawks (Accipiter gentilis) that of day-active red squirrels (Sciurus vulgaris). Unexpectedly, the amount of preferred habitat had no effect on nest box use, but, surprisingly, both squirrel species seemed to benefit from close proximity to agricultural fields and red squirrels to urban areas. We found no evidence of trade-off between settling in a high-quality habitat and avoiding predators. However, the amount of poor-quality young pine forests was lower in occupied sites where goshawks were present, possibly indicating habitat specific predation on red squirrels. The results suggest that erecting nest boxes for Ural owls should be avoided in the vicinity of flying squirrel territories in order to conserve the near threatened flying squirrels. Our results also suggest that flying squirrels do not always need continuous old forests, and hence the currently insufficient conservation practices could be improved with reasonable increases in the areas left untouched around their nests. The results of this study demonstrate the importance of taking into account both habitat requirements and predation risk as well as their interactive effects when modeling the occupancy of threatened animal species and planning their conservation

Energiförbrukning och potentiell energibesparing vid badanläggningar : förstudie /

1. The relative contributions of habitat and food availability on fitness may provide evidence for key habitat features needed to safeguard population persistence. However, defining habitat quality for a species can be a complex task, especially if knowledge on the relationship between individual performance and habitat quality is lacking. 2. Here, we determined the relative importance of availability of suitable forest habitat, body mass, and food from masting tree species on female lifetime reproductive success (LRS) of Siberian flying squirrels (Pteromys volans). 3. We calculated LRS of 500 female flying squirrels based on a 22 year-long longitudinal data set of two populations from western Finland. We assessed with generalised additive models the potential effects of availability of suitable habitat and cumulative lifetime availability of food from masting tree species on female LRS, longevity and fecundity. On a reduced dataset, we evaluated the importance of female winter body mass and conducted a piecewise path analysis to determine how variables were connected. 4. According to generalised additive models female longevity, fecundity and LRS were mainly determined by variation in cumulative lifetime availability of food from masting alder and birch. Instead, habitat and body mass had smaller role. The path analysis indicated that lifetime food availability had direct effect on longevity and fecundity, and these had equal effect on LRS at both study sites. 5. Our results on LRS shows that the occurrence of tree masting events during a flying squirrel female’s lifetime have profoundly larger effect on lifetime reproductive success than the cover of suitable forest habitat. Furthermore, this study emphasises the importance of both fecundity and longevity, and the indirect effects of food availability via those components, as determinants of lifetime fitness of female flying squirrels

Landscape homogenization due to agricultural intensification disrupts the relationship between reproductive success and main prey abundance in an avian predator

Background: Selecting high-quality habitat and the optimal time to reproduce can increase individual fitness and is a strong evolutionary factor shaping animal populations. However, few studies have investigated the interplay between land cover heterogeneity, limitation in food resources, individual quality and spatial variation in fitness parameters. Here, we explore how individuals of different quality respond to possible mismatches between a cue for prey availability (land cover heterogeneity) and the actual fluctuating prey abundance. Results: We analyse timing of breeding and reproductive success in a migratory population of Eurasian kestrels (Falco tinnunculus) breeding in nest-boxes, over a full three-year abundance cycle of main prey (voles), and consider several components of individual quality, including body condition, blood parasite infection, and genetic diversity (n = 448 adults) that act on different time scales. Older individuals, and kestrel parents in higher body condition started egg-laying earlier than younger birds and those in lower body condition. Additionally, egg-laying was initiated earlier during the increase and decrease phases (2011 and 2012) than during the low phase of the vole cycle (2013). Nestling survival (ratio of eggs that fledged successfully) was higher in early nests and in heterogeneous landscapes (i.e., mosaic of different habitat types), which was evident during the increase and decrease phases of the vole cycle, but not during the low vole year. Conclusions: We found a strong positive effect of landscape heterogeneity on nestling survival, but only when voles were relatively abundant, whereas a difference in the timing of breeding related to territory landscape heterogeneity was not evident. Therefore, landscape heterogeneity appeared as the main driver of high reproductive performance under favourable food conditions. Our results show that landscape homogenization linked to agricultural intensification disrupts the expected positive effect of vole abundance on reproductive success of kestrels.</div

Muscle-to-Brain communication in the context of obesity: impact of physical exercise?

editorial reviewedMuscle-to-Brain communication in the context of obesity: impact of physical exercise? A. Delpierre (1), C. Deroux (2), L. Ris (2), A-E. Declèves (3), A. Legrand (1), A. Villers (2) and A. Tassin (1) (1) Lab. of Respiratory Physiology and Rehabilitation, UMONS (2) Lab. of Neurosciences, UMONS (3) Lab. of Metabolic and Molecular Biochemistry, UMONS Exercise training (ET) has a positive effect on brain health. During ET, skeletal muscle releases specific myokines among them potential regulators of hippocampal function, like Irisin, released by cleavage of FNDC5. Also expressed in the brain, FNDC5 contributes to increase the level of brain-derived neurotrophic factor (BDNF). However, the contribution of muscle-derived Irisin on cognitive function remains controversial, as well as the influence of obesity or ET modalities. The goal of our study is to determine (i) inter-relationships between FNDC5/Irisin pathway and cognition depending on ET modalities and (ii) whether muscle-to-brain crosstalk is altered in the context of obesity. Two ET modalities were compared in Low-Fat (LF) and High-Fat (HF) fed mice: volontary (enriched environment) and forced ET (endurant). Irisin plasmatic level is increased by ET, whatever ET modality or diet. As concern FNDC5, volontary ET is associated to an increased protein level in LF but not in HF mouse muscles while forced ET does not modify FNDC5 protein level in muscular or brain tissues. Enrichment in mice improves spatial learning and memory. However, the BDNF protein level is not modified by volontary ET in the cortex and hippocampus. Forced ET does not modify spatial learning and memory and BDNF protein level in the hippocampus. However, BDNF protein level is increased in the brain cortex by endurance- training and surprisingly, by HF diet. In conclusion, ET increases Irisin plasmatic level and enrichment improves cognitive function in mice. FNDC5 protein level depend on training modalities, is tissue-specific and influenced by diet.Etude translationnelle de la communication muscle-cerveau lors d’un reconditionnement musculaire appliqué dans un contexte d’obésité. - Sources privée

Muscle-to-brain communication in the context of obesity : impact of physical exercise

editorial reviewedExercise training (ET) has a positive effect on brain health. Although molecular mechanisms underlying ET benefits are still poorly understood, a cross-talk between skeletal muscle and brain has been described. During ET, muscle releases specific myokines among which potential regulators of hippocampal function, like Irisin. This exerkine is a PGC1α-dependant myokine released by cleavage of FNDC5. Also expressed in the brain, FNDC5 contributes to increase the level of brain-derived neurotrophic factor. However, the contribution of muscle-derived Irisin on cognitive function remains controversial, as the influence of obesity or ET modalities. The goal of our study is to determine (i) inter-relationships between FNDC5/Irisin pathway and cognition in function of ET modalities and (ii) whether muscle-to-brain crosstalk is altered in the context of obesity. To this aim, two ET modalities were compared in mice: spontaneous ET (environmental enrichment) and endurance ET (training sessions on a treadmill). Mice were fed either with a Low-Fat (LF) or an High-Fat (HF) diet. ET reduces weight gain and fasting glycaemia in obese mice. Environmental enrichment improves spatial learning and memory (Morris Water Maze test), particularly in obese animals. Irisin plasmatic level is enhanced by a HF diet and endurance ET. In muscles, FNDC5 protein level is also modified by ET and diet. In brain, ET improves BDNF protein level. In conclusion, ET modalities and obesity influence FNDC5/Irisin pathway and cognitive functions in mice. Further studies are necessary to understand the contribution of muscle-derived Irisin to ET effects

Inter-communication muscle - cerveau dans un contexte d'obésité : Impact de l'exercice

L'entrainement en endurance se présente comme bénéfique dans la lutte contre l'obésité et ses troubles associés. En effet, au niveau cérébral, une augmentation de la plasticité, de la différenciation et de la survie neuronale ont été décrites dans la littérature. Ces observations peuvent être causées par une série de facteurs neurotrophiques eux-même stimulé par FNDC5, précurseur d'une exerkine nommée Irisine. La voie entrainement-muscle-Irisine/FNDC5-Cerveau pourrait être la clé dans l'approche de nouvelle stratégies thérapeutiques au niveau cérébral. Cependant les mécanismes par lesquels l'Irisine est modulée et stimule les facteurs neurotrophiques sont peu connus et cela particulièrement dans un contexte d'obésité

Antenne à fentes à cavité pour fusée expérimentale

National audienceCe papier présente une antenne à fentes à cavité intégrée dans le fuselage d'une fusée expérimentale. L'antenne a été conçue grâce au logiciel ANSYS HFSS pour un système de télémesure émettant entre 869,4 et 869,65 MHz. Elle offre un gain réalisé de 6,2 dBi en simulations. La fabrication et les mesures de paramètres S de cette topologie inédite pour l'application sont présentées

Biased sex ratios in Western Europe populations of little bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities

Adult sex ratios (ASRs) have proved to correlate with population trends, which make them potential useful indicators of a species’ population trajectory and conservation status. We analysed ASRs and proportion of juveniles in flocks of an endangered steppe bird, the Little Bustard Tetrax tetrax, using surveys made during the non-breeding period in seven areas within its Western European range (one in Portugal, four in Spain, and two in France). We found overall male-biased ASRs, as all the seven surveyed areas showed a male-biased ASR mean value. Five areas were below the threshold median value (female sex ratio = 0.4) considered to be consistent with an increased probability of extinction, according to earlier population viability analyses for the species. We also found a significant positive correlation between female ratio and the proportion of young individuals in the non-breeding flocks surveyed. Our results (strongly male-biased ASRs) support the hypothesis that the viability of Little Bustard populations in Western Europe is threatened by an excess of female mortality, something that should be quantified in the future, and emphasise the value of monitoring sex ratio as a population viability indicator in species where monitoring survival is difficult to achieve.This paper is a contribution to the REMEDINAL 3 (S2013/MAE-2719) network which funded a post-doc contract for ESD. It also contributes to the Excellence Network REMEDINAL 3CM (S2013/ MAE2719), supported by Comunidad de Madrid. We thank all the field workers that collaborated in this study. Thanks to Ricardo Montero from Extremadura Birding who provided us with a Little Bustard winter flock video record. We are grateful to Julia Gómez-Catasús for her help with the bootstrapping analysis. This study was carried out with no funds from the Spanish Ministry of Science and Innovation

Développement d'une trousse de dosage d'organokines par spectrométrie de masse

Lors d'une prise en charge thérapeutique, l'identification de marqueurs biologiques permettant un meilleur diagnostic ainsi qu'une caractérisation évolutive du patient est essentielle. A cet égard, les organokines occupent une place importante car elles sont considérées comme des médiateurs moléculaires de la communication (cross-talk) inter-organes. Nous développons actuellement une méthode de quantification multiplexe de ces organokines. Cette recherche s'inscrit dans une des thématiques phares de l'Institut de Recherche Santé de l'UMONS et résulte d'une collaboration entre 6 services de l'Institut dans le domaine de la biomédecine intégrative. L'identification d'altérations du cross-talk inter-organes vise au développement futur de nouvelles stratégies thérapeutiques dans différents contextes pathologiques. Les organokines sont produites à partir de divers organes tels le tissu adipeux (adipokines), les muscles striés squelettiques (myokines), le foie (hépatokines), ou encore le cerveau (neurokines). Chacune de ces molécules est relarguée dans la circulation sanguine et agit ensuite à distance au niveau d'autres tissus et organes, jouant un rôle essentiel dans la coordination et le maintien de l'homéostasie, notamment métabolique. Il est aujourd'hui reconnu qu'une production ainsi qu'une libération excessive et inappropriée de ces organokines participe au développement et à la progression de pathologies comme l'obésité, le diabète de type 2 et les maladies cardiovasculaires. Actuellement, les organokines sont dosées individuellement par l'utilisation de tests ELISA ou RIA. Ces approches, non seulement coûteuses, n'existent pas pour toutes les organokines d'intérêt. Dans ce contexte, la spectrométrie de masse, approche très sensible, permet la quantification simultanée de nombreuses protéines dans différentes matrices biologiques dont le sérum ou le plasma. Ce projet implique une approche translationnelle directement en lien avec la clinique. Cette approche permettra d'acquérir une vision globale et intégrée des mécanismes de communication inter-organes impliqués dans les pathologies étudiées et de développer ainsi des stratégies thérapeutiques innovantes