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Spatiotemporal patterns of microbial composition and diversity in precipitation
No full textMicrobes in the atmosphere have broad ecological impacts, including the potential to trigger precipitation through species and strains that act as ice nucleation particles. To characterize spatiotemporal trends of microbial assemblages in precipitation we sequenced 16S (bacterial) and 18S (fungal) rRNA gene amplicon libraries collected from 72 precipitation events in three US states (Idaho, Louisiana, and Virginia) over four seasons. We considered these data from the perspective of a novel metacommunity framework. In agreement with our heuristic, we found evidence for distinct mechanisms underlying the composition and diversity of bacterial and fungal assemblages in precipitation. Specifically, we determined that: 1) bacterial operational taxonomic unit (OTU) composition of precipitation was strongly associated with macroscale drivers including season and high altitude characteristics of storms; 2) fungal OTU composition was strongly correlated with mesoscale drivers including particular spatial locations; 3) β‐diversity (heterogeneity of taxa among samples) for both bacteria and fungi was largely maintained by turnover of taxa; however, 4) bacterial assemblages had higher contributions to total β‐diversity from nestedness (i.e., lower richness assemblages were largely taxonomic subsets of richer assemblages), due to losses of taxa during dispersal, particularly among potential ice nucleation active bacteria; and 5) fungal assemblages had higher contributions to total β‐diversity from turnover due to OTU replacement. Spatiotemporal trends in precipitation‐borne metacommunities allowed delineation of a large number of statistically significant indicator taxa for particular sites and seasons, including trends for bacteria that are potentially ice nucleation active. Our findings advance understanding regarding the dispersion of aerosolized microbes via wet deposition, and the development of theory concerning potential assembly rules for bioaerosol assemblages
Milk metabolites as noninvasive indicators of nutritional status of mid-lactation Holstein and Montbéliarde cows
No full textThe objective was to investigate the effects of feed restriction on concentrations of selected milk metabolites in midlactation Holstein and Montbéliarde cows, and explore their correlations with energy balance and classic plasma and milk indicators of nutritional status. Eight Holstein and 10 Montbéliarde cows (165 ± 21 DIM) underwent 6 d of feed restriction during which feed allowance was reduced to meet 50% of their net energy for lactation (NEL) requirements. The experiment was divided in four periods: Control (CONT; d -3 to -1), restriction (REST; d 1 to 6), WEEK1 (d 7 to 13) and WEEK2 (d 14 to 18) after refeeding at ad libitum intake. Intake, milk production, energy balance and plasma metabolites were used to validate the feed restriction model. Concentrations of seven milk metabolites, i.e. BHB, glucose, glucose-6-phosphate, isocitrate, glutamate, uric acid and free amino groups were measured in morning milk samples, and fatty acids in pooled PM and AM samples. Feed restriction induced a negative energy balance (-42.5 ± 4.4 MJ/d), increased plasma non-esterified fatty acids and BHB, and decreased plasma glucose concentrations. Feed restriction increased milk glucose-6-phosphate and isocitrate (+38% and +39%, respectively) and decreased milk BHB, glucose, glutamate, uric acid and free amino group concentrations (-20%, -57%, -65%, -42% and -14%, respectively), compared to pre- restriction. Milk concentrations of medium chain fatty acids (e.g. sum of C10 to C15) decreased and those of long chain (e.g. 18:0, cis-9 18:1) increased during restriction. Breed differences were not detected for the majority of variables. All studied milk metabolites were significantly correlated with energy balance (rs = 0.48, 0.63, -0.31, -0.45, 0.61 for BHB, glucose, glucose-6-phosphate, isocitrate and glutamate, respectively). Milk glucose and glutamate were the most correlated with plasma metabolites and milk FA associated with lipomobilization. These results suggest that milk metabolites may be used as noninvasive indicators of NEB and metabolic status of dairy cows
A tool for reflecting on research stances to support sustainability transitions
No full textThe success of transdisciplinary approaches to address sustainability problems largely depends on the compatibility between the research stances of the researchers involved. A research stance is the strategy used to deal with an indeterminate situation, and influences choices at all steps in knowledge production, such as defining a problem in scientific terms or selecting methods. These choices encompass epistemology, methodology and implementation. We present a heuristic tool for researchers to reflect on the choices that define their own research stances. Designed and tested as part of doctoral training, this tool uncovers how research choices can lead to a wide range of research stances about a situation that requires action. Our tool allows researchers to articulate and discuss their research stances, to facilitate their management within a project. It is also useful to understand the relevance for action of the knowledge they generate
Bdellovibrio and like organisms in lake geneva: An unseen elephant in the room?
No full textWhen considering microbial biotic interactions, viruses as well as eukaryotic grazers are known to be important components of aquatic microbial food webs. It might be the same for bacterivorous bacteria but these groups have been comparatively less studied. This is typically the case of the Bdellovibrio and like organisms (BALOs), which are obligate bacterial predators of other bacteria. Recently, the abundance and distribution of three families of this functional group were investigated in perialpine lakes, revealing their presence and quantitative importance. Here, a more in-depth analysis is provided for Lake Geneva regarding the diversity of these bacterial predators at different seasons, sites and depths. We reveal a seasonal and spatial (vertical) pattern for BALOs. They were also found to be relatively diverse (especially Bdellovibrionaceae) and assigned to both known and unknown phylogenetic clusters. At last we found that most BALOs were positively correlated to other bacterial groups, mainly Gram-negative, in particular Myxococcales (among which many are predators of other microbes). This study is the first shedding light on this potentially important bacterial killing group in a large and deep lake
Hypothesis paper: electroacupuncture targeting the gut–brain axis to modulate neurocognitive determinants of eating behavior - toward a proof of concept in the obese minipig model
No full textAcupuncture has thousands of years of history and perspective for the treatment of many health problems and disorders. Beneficial effects of acupuncture on obesity have been demonstrated at various levels in animals and clinical trials, with almost no adverse effect, even when combined with local electrical stimulation, i.e., electroacupuncture (EA), a way to potentiate the effects of acupuncture. However, there is still scattered evidence about the impact of EA on brain functions related to the control of eating behavior, and notably on the gut–brain axis mechanisms involved in these putative central modulations. During the past 10 years, we have described a convincing diet-induced obese minipig model, and successfully implemented brain imaging and neurocognitive approaches to challenge mechanistic hypotheses and innovative therapeutic strategies. In the present article, we propose to confront the current literature on the acupuncture and EA effects on the gut–brain axis and obesity with the latest developments in nutrition and neuroscience research using the minipig model. Our aims are to (a)
elaborate functional hypotheses on the gut–brain mechanisms underlying EA effects on obesity, and especially on the role of the vagus nerve, and (b) present the rational for testing these hypotheses in the minipig model
Permanent grassland classifications predict agronomic and environmental characteristics well, but not ecological characteristics
No full textPermanent grasslands produce highly diverse ecosystem goods and services, which need to be easily assessed by decision makers. Naturalists and agronomists classify grasslands in different ways to predict ecological, agronomic and environmental characteristics of the grasslands. However, few studies have compared the prediction abilities of these different classifications using the same botanical releves, and none has explored the utility of combining classifications. In this study, we attributed a grassland class from each of three classifications (phytosociological, agronomic and functional) to 250 permanent grasslands in north-eastern France to predict 16 characteristics: nine ecological, three agronomic and four environmental. We used statistical model selection to identify the classification or combination of classifications that best predicted each characteristic. Our results showed great prediction ability of agronomic classification, which created the best models for predicting agronomic (yield) and environmental (management, elevation) characteristics. We also identified a strong prediction ability of combining two or all three classifications to predict seven other grassland characteristics. However, grassland classifications did not predict most of the ecological characteristics well. We can assume that phytosociological classification, despite its mainstream use, predicts grassland characteristics less well than agronomic classification. We recommend combining grassland classifications to improve rapid prediction abilities. This study provides new knowledge useful for developing grassland classifications which meet the needs of agronomists and naturalists
Place des sciences humaines et sociales dans les controverses associées à la notion de Service écosystémique (SE)
No full textL’impact des attributs et indicateurs de qualité sur le comportement d’achat d’un produit alimentaire : une approche exploratoire, par la valeur perçue et l’authenticité perçue : cas de l’huile d’olive d’Algérie
No full textCette recherche s’interroge sur la relation entre la valeur perçue et l’authenticité perçue, deux variables perceptuelles clés du processus décisionnel du consommateur. Une étude exploratoire appliquée au cas de l’huile d’olive d’Algérie a été menée. Trente entretiens individuels conduits auprès d’experts de la filière oléicole algérienne et des consommateurs ont permis d’identifier :
1) les facteurs qui contribuent à construire la valeur perçue d’un produit alimentaire ainsi que ceux
qui contribuent à construire son authenticité perçue ;
2) le rôle de l’authenticité perçue dans la formation de la valeur perçue ;
3) et les conséquences de cette relation en termes de comportements d’achat et post-achat.
En conclusion, un modèle théorique reprenant ces concepts et leurs liens est proposé pour être testé.This research questions the relationship between perceived value and perceived authenticity, two key perceptual variables of consumer decision-making. An exploratory study applied to the case of olive oil from Algeria was conducted. Thirty individual interviews conducted with experts from the Algerian olive oil sector and consumers have identified:
1) the factors that contribute to building the perceived value of a food product as well as those that
contribute to its perceived authenticity;
2) the role of perceived authenticity in the formation of perceived value;
3) and the consequences of this relationship in terms of purchasing and post-purchase behavior.[br/]
In conclusion, a theoretical model presenting these concepts and their links is proposed to be tested
