From dust bowl to dust bowl:soils are still very much a frontier of science

When the Soil Science Society of America was created, 75 yr ago, the USA was suffering from major dust storms, causing the loss of enormous amounts of topsoil as well as human lives. These catastrophic events reminded public officials that soils are essential to society’s well-being. The Soil Conservation Service was founded and farmers were encouraged to implement erosion mitigation practices. Still, many questions about soil processes remained poorly understood and controversial. In this article, we argue that the current status of soils worldwide parallels that in the USA at the beginning of the 20th century. Dust bowls and large-scale soil degradation occur over vast regions in a number of countries. Perhaps more so even than in the past, soils currently have the potential to affect populations critically in several other ways as well, from their effect on global climate change, to the toxicity of brownfield soils in urban settings. Even though our collective understanding of soil processes has experienced significant advances since 1936, many basic questions still remain unanswered, for example whether or not a switch to no-till agriculture promotes C sequestration in soils, or how to account for microscale heterogeneity in the modeling of soil organic matter transformation. Given the enormity of the challenges raised by our (ab)uses of soils, one may consider that if we do not address them rapidly, and in the process heed the example of U.S. public officials in the 1930s who took swift action, humanity may not get a chance to explore other frontiers of science in the future. From this perspective, insistence on the fact that soils are critical to life on earth, and indeed to the survival of humans, may again stimulate interest in soils among the public, generate support for soil research, and attract new generations of students to study soils

The crystal structure of Fe₄S₄ quinolinate synthase unravels an enzymatic dehydration mechanism that uses tyrosine and a hydrolase-type triad.

International audienceQuinolinate synthase (NadA) is a Fe4S4 cluster-containing dehydrating enzyme involved in the synthesis of quinolinic acid (QA), the universal precursor of the essential nicotinamide adenine dinucleotide (NAD) coenzyme. A previously determined apo NadA crystal structure revealed the binding of one substrate analog, providing partial mechanistic information. Here, we report on the holo X-ray structure of NadA. The presence of the Fe4S4 cluster generates an internal tunnel and a cavity in which we have docked the last precursor to be dehydrated to form QA. We find that the only suitably placed residue to initiate this process is the conserved Tyr21. Furthermore, Tyr21 is close to a conserved Thr-His-Glu triad reminiscent of those found in proteases and other hydrolases. Our mutagenesis data show that all of these residues are essential for activity and strongly suggest that Tyr21 deprotonation, to form the reactive nucleophilic phenoxide anion, is mediated by the triad. NadA displays a dehydration mechanism significantly different from the one found in archetypical dehydratases such as aconitase, which use a serine residue deprotonated by an oxyanion hole. The X-ray structure of NadA will help us unveil its catalytic mechanism, the last step in the understanding of NAD biosynthesis

Why is narrative inquiry suitable to study motivation? Insights from two empirical studies

Narrative Inquiry (NI) is increasingly recognised in language education research because it offers profound means of exploring learners' and educators' lived experiences through storytelling and/or story-making. Specifically, this article explores NI's suitability for studying motivation in language learning, highlighting its ability to capture the dynamic and multifaceted nature of motivational trajectories. Grounded in postmodernist perspectives, NI emphasises individuality and the complexities of human experiences, thereby bridging gaps in more traditional and established motivation research approaches. The innovations of this research perspective include a nuanced exploration of motivation as a temporal, contextual, and personal construct. The article showcases two empirical studies employing NI: the longitudinal examination of Chinese postgraduate students' motivational shifts in the UK, and the lifelong motivational journeys of older adult language learners in France. These studies illustrate how NI captures evolving motivational dynamics influenced by personal, social, and institutional factors. Through co-constructed narratives, NI fosters deep participant-researcher relationships, which emphasises reflexivity and participant agency, while revealing intricate motivational patterns. Furthermore, NI addresses methodological gaps in existing motivation research and offers analytical versatility. Ultimately, this article argues that NI transcends traditional research boundaries by providing a more holistic, person-centred lens to understand motivation's complexities. By celebrating the richness of individual narratives, NI emerges as an empowering approach to investigate and represent the interplay between context, personal trajectories and motivation in language learning

A role for nickel-iron cofactors in biological carbon monoxide and carbon dioxide utilization

Ni–Fe containing enzymes are involved in the biological utilization of carbon monoxide, carbon dioxide, and hydrogen. Interest in these enzymes has increased in recent years due to hydrogen fuel initiatives and concerns over development of new methods for CO2 sequestration. One Ni–Fe enzyme called carbon monoxide dehydrogenase (CODH) is a key player in the global carbon cycle and carries out the interconversion of the environmental pollutant CO and the greenhouse gas CO[subscript 2]. The Ni–Fe center responsible for this important chemistry, the C-cluster, has been the source of much controversy, but several recent structural studies have helped to direct the field toward a unifying mechanism. Here we summarize the current state of understanding of this fascinating metallocluster.National Institutes of Health (U.S.) (GM69857)Massachusetts Institute of Technology. Energy InitiativeHoward Hughes Medical Institute. Investigato

Artificial Intelligence: A Tale of Social Responsibility

Conversely to the legislation that struggles to develop, regulate and supervise the use of artificial intelligence (AI), the civil society, that gradually realizes the fundamental issues and perspectives induced by this new technology, slowly starts to take responsibility and to mobilize. Social responsibility expresses itself through the emergence of new voluntary standards, that could integrate the concept of social good with the use of AI. More precisely, this paper proposes to develop three axes of tools for the social responsibility in AI, including stakeholder awareness, the integration of ethical and technical standards to induce good behaviors, and the incitement to a responsible AI

Emergent properties of microbial activity in heterogeneous soil microenvironments:Different research approaches are slowly converging, yet major challenges remain

Over the last 60 years, soil microbiologists have accumulated a wealth of experimental data showing that the usual bulk, macroscopic parameters used to characterize soils (e.g., granulometry, pH, soil organic matter and biomass contents) provide insufficient information to describe quantitatively the activity of soil microorganisms and some of its outcomes, like the emission of greenhouse gases. Clearly, new, more appropriate macroscopic parameters are needed, which reflect better the spatial heterogeneity of soils at the microscale (i.e., the pore scale). For a long time, spectroscopic and microscopic tools were lacking to quantify processes at that scale, but major technological advances over the last 15 years have made suitable equipment available to researchers. In this context, the objective of the present article is to review progress achieved to date in the significant research program that has ensued. This program can be rationalized as a sequence of steps, namely the quantification and modeling of the physical-, (bio)chemical-, and microbiological properties of soils, the integration of these different perspectives into a unified theory, its upscaling to the macroscopic scale, and, eventually, the development of new approaches to measure macroscopic soil characteristics. At this stage, significant progress has been achieved on the physical front, and to a lesser extent on the (bio)chemical one as well, both in terms of experiments and modeling. In terms of microbial aspects, whereas a lot of work has been devoted to the modeling of bacterial and fungal activity in soils at the pore scale, the appropriateness of model assumptions cannot be readily assessed because relevant experimental data are extremely scarce. For the overall research to move forward, it will be crucial to make sure that research on the microbial components of soil systems does not keep lagging behind the work on the physical and (bio)chemical characteristics. Concerning the subsequent steps in the program, very little integration of the various disciplinary perspectives has occurred so far, and, as a result, researchers have not yet been able to tackle the scaling up to the macroscopic level. Many challenges, some of them daunting, remain on the path ahead

Le rôle des associations locales dans l’effectivité de la protection juridique de l’animal

« Les hommes ont oublié cette vérité, dit le renard.Mais tu ne dois pas l’oublier.Tu deviens responsable pour toujours de ce que tu as apprivoisé. » Si dans leurs desseins de développement anthropocentré, les hommes ont oublié cette vérité, Antoine de Saint-Exupéry nous rappelle à nos devoirs avec une grande sagesse. Au cours de son évolution, l’être humain s’est approprié le monde, exploitant tout ce qui s’y trouvait de manière démesurée pour ses propres intérêts. Cependant, l’œuvre citée pr..

Deglaciation history at the Alpine-Mediterranean transition (Argentera-Mercantour, SW Alps) from 10Be dating of moraines and glacially polished bedrock

International audienceEstimating the extent and age of the last glacial maxima as well as the chronology of glacial recessions in various environmental contexts is key to source-to-sink studies and paleoclimate reconstructions. The Argentera-Mercantour massif being located at the transition between the Alps and the Mediterranean Sea, its deglaciation chronology can be compared to the sediment budget of the Var River marine delta. In this paper, the deglaciation is constrained by 13 new and 22 reassessed Cosmic-Ray Exposure (CRE) 10Be datings of moraines and polished crystalline bedrocks. These data allow for the first time to fully reconstruct the deglaciation history at the scale of the entire massif, in agreement with a major glacier recession at ca. 15 ka, at the onset of Bølling transition. This contribution reveals a glacier–climate relationship more sensitive to warming phases in the southern Alps highlighted by a major decrease of glaciers after ca. 15 ka. This major deglaciation is correlated with a 2.5 fold decrease of sediment discharge of rivers into the Mediterranean Sea. Main deglaciation of the massif upper slopes (2,700-2,800 m a.s.l.) occurred after the LGM at 20.8-18.6 ka, followed by the lower slopes (2,300 m a.s.l.) at 15.3-14.2 ka. Finally, the flat polished surfaces above 2,600 m a.s.l. and the zones confined within narrow lateral valleys were likely affected by progressive ice melting of remaining debris covered glaciers and moraine erosion following the Younger Dryas re-advance stage between 12 and 8-9 ka. At lower elevations, a sediment core in the Vens Lake located at 2,300 m a.s.l., shows onset of lake sedimentation at ca. 14 ka and a transition towards a vegetated environment after 8 ka. Final stabilization of moraines occurred at 5 ka, which might reflect denudation acceleration during the Holocene humid phase

Mosaicism in domestic carnivores

Le mosaïcisme est un phénomène génétique retrouvé dans l’ensemble du monde vivant et notamment chez toutes les femelles de mammifères, qui sont des mosaïques du fait du phénomène d’inactivation aléatoire du chromosome X. Chez le chat, ce phénomène épigénétique a la particularité de pouvoir être directement visible sur la robe de certains individus : les chats à robe écaille de tortue et tricolore. Les rares mâles portant ces robes sont le plus souvent stériles du fait d’une anomalie chromosomique. Chez le chien, comme chez le chat, un mosaïcisme fréquemment décrit concerne les chromosomes sexuels et peut être la cause de troubles du développement de l’appareil génital entraînant le plus souvent une stérilité. Les tests génétiques sont un nouvel outil à envisager par le praticien face à des hypothèses de mosaïcisme, voire de chimérisme.Mosaicism is a common genetic phenomenon that occurs in many pluricellular organisms and more particularly in female mammals. They are mosaics because of the X-chromosome inactivation. In domestic cats, this epigenetic phenomenon can moreover be seen at first glance on some individuals: tortie and calico cats. In fact, some males are very rarely seen with such a coat color, but they are most of the time sterile because of a chromosomic anomaly. Moreover, in dogs and cats, sex chromosome mosaicism, often described, may induce disorders of sexual development leading to sterility. Genetic tests could be a useful tool for clinicians in order to identify and distinguish mosaicism or chimerism

Wastewater irrigation: the state of play

As demand for fresh water intensifies, wastewater is frequently being seen as a valuable resource. Furthermore, wise reuse of wastewater alleviates concerns attendant with its discharge to the environment. Globally, around 20 million ha of land are irrigated with wastewater, and this is likely to increase markedly during the next few decades as water stress intensifies. In 1995, around 2.3 billion people lived in water-stressed river basins and this could increase to 3.5 billion by 2025. We review the current status of wastewater irrigation by providing an overview of the extent of the practice throughout the world and through synthesizing the current understanding of factors influencing sustainable wastewater irrigation. A theme that emerges is that wastewater irrigation is not only more common in water-stressed regions such as the Near East, but the rationale for the practice also tends to differ between the developing and developed worlds. In developing nations, the prime drivers are livelihood dependence and food security, whereas environmental agendas appear to hold greater sway in the developed world. The following were identified as areas requiring greater understanding for the long-term sustainability of wastewater irrigation: (i) accumulation of bioavailable forms of heavy metals in soils, (ii) environmental fate of organics in wastewater-irrigated soils, (iii) influence of reuse schemes on catchment hydrology, including transport of salt loads, (iv) risk models for helminth infections (pertinent to developing nations), (v) microbiological contamination risks for aquifers and surface waters, (vi) transfer efficiencies of chemical contaminants from soil to plants, (vii) health effects of chronic exposure to chemical contaminants, and (viii) strategies for engaging the public.<br /