Journal of Next-Generation Research 5.0
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Cooling, vegetation shift and decline in monsoonal rainfall in NE Tibet through the greenhouse to icehouse transition
No full textInternational audienceUnderstanding how and why global climate tipped from greenhouse to icehouse conditions remains a major challenge.This critical shift is well documented in the marine realm characterized by a steady decline in global temperatureuntil a large and rapid cooling step at the Eocene-Oligocene Transition (EOT). However, the chronology andmechanisms of cooling on land remain unclear. To reconstruct Paleogene climate conditions for the Tibetan Plateauand the Asian continental interior, clumped isotope thermometry and palynology in accurately-dated continentalrecords from northeastern Tibet, are here combined with climate and vegetation simulations. Our results show twosuccessive dramatic (>9 C) drops in soil carbonate temperature, at 37 Ma and at 33.5 Ma associated respectivelywith the appearance and dominance of high altitude conifer forests. Such large temperature decreases associatedwith ecological reorganisations cannot result from regional cooling alone. They require shifting of the rainy seasonto cooler months, which we interpret to reflect a decline of monsoonal intensity. Our results suggest that theresponse of Asian temperatures, monsoonal rainfall and vegetation to the decline of atmospheric CO2 and globaltemperature through the late Eocene occurred in two steps separated by a period of climatic instability. Our resultssupport the onset of the Antarctic Circumpolar Current coeval to the Oligocene isotope event 1 (Oi-1) glaciationat 33.5 Ma, reshaping the distribution of surface heat worldwide; however, the origin of the 37 Ma cooling eventremains to be determined
Mine versus Wild : a plant conservation checklist of the rich Iron-Ore Ngovayang Massif Area (South Cameroon)
No full textInternational audienceBackground and aims – The rapid expansion of human activities in South Cameroon, particularly mining in mountainous areas, threatens this region’s exceptional biodiversity. To comprehend the effects of land-use change on plant diversity and identify conservation priorities, we aim at providing a first comprehensive plant checklist of the Ngovayang Massif, focusing on the two richest plant families, Orchidaceae and Rubiaceae.Location – The Ngovayang Massif Area (NMA) is located in the South Region of Cameroon. It is covered by lowland and submontane rainforest (100 to 1110 m elevation).Methods – We compiled a dataset of 6116 georeferenced herbarium specimens, of which 2787 belong to Rubiaceae and Orchidaceae. We used rarefaction methods to explore sampling and diversity patterns, and investigated the altitudinal distribution of rare and/or threatened taxa.Key results – The NMA, which houses about 1500 vascular plant taxa, is the richest documented area for Rubiaceae in Atlantic Central Africa (ACA) and the fifth for Orchidaceae, with respectively 281 and 111 taxa. Among these taxa, 178 (45%) are endemic to ACA and 67 (17%) are considered globally threatened according to IUCN categories and criteria. We show that higher elevation areas (> 750 m), which are also the main areas targeted for mining, are the richest in endangered and/or rare species. Three new records for Cameroon are reported here.Conclusion – The NMA represents an Important Plant Area of Cameroon as confirmed by its exceptional plant diversity (> 20% of the total Flora of Cameroon), by the concentration of many threatened and/or restricted range species (10 taxa are strict endemics of the massif) as well as by the threat on rare habitats (i.e. the submontane vegetation above ~750 m elevation). A management plan involving in situ and ex situ conservation actions is urgently needed to reduce the potential threats of future mining activities
Modelling of early diagenesis of lacustrine carbonates associated with Mg-silicates
No full textInternational audienceDiagenetic processes occuring in time and space are critical in the evolution of sedimentary rocks. They need to be assessed to improve our abilities for palaeoenvironmental interpretations. A numerical model was developed with the reactive transport code CrunchFlow to assess the chemical and physical processes occurring during the early diagenesis of lacustrine carbonates formed in rift settings, using as a case study the carbonate sediments associated with Mg-silicates of the alkaline volcanic crater lake, Dziani Dzaha. The model relies on the solid phase compositions of the first meter of sediments, the porosity, the pore water chemistry and an age model for the sediment based on radiocarbon measurements. Chemical and isotope analyses reveal the inflow of magmatic CO 2 and intense microbial methanogenesis activity in the lake. The alkaline pH of the lake induce oversaturation of porewaters relative to aragonite, hydromagnesite and saponite. Carbonates form close to equilibrium and dominate the mineralogy of the shallow sediment while kinetic effects inhibit the formation of saponite that precipitate only at depth. Magmatic CO 2 inflow and microbial degradation of organic matter cause a decrease of pH that destabilized hydromagnesite. The model brings new insights on the palaeoenviroments and on the early diagenetic processes leading to the lacustrine carbonates formed in rift settings. It quantifies the mechanisms involved in the early diagenetic processes (e.g. input of mantellic CO 2) without which minerals reactivity, pH and porosity would not be described over the sediment depth. This study represents a first step towards the forward modeling of the evolution of the solid and fluid phases of carbonate sediments from their deposition at sediment surface to their current settings in the sedimentary column
Les paroles militantes dans les controverses environnementales
No full textQuestions de communication, série actes 37.International audienceDu projet d'aéroport de Notre-Dame-des-Landes au projet « Montagne d'or » en Guyane, du barrage de Sivens à l’oléoduc géant du Dakota du Nord, les contestations citoyennes se multiplient, et, autour d’elles, émergent toute une série d’acteurs qui élèvent leur voix en faveur des projets ou contre eux. Discours et contre-discours font de la parole publique un enjeu majeur des controverses environnementales.Ce volume explore et redéfinit les « paroles militantes » en abordant les controverses environnementales en tant que double processus: rhétorique et de publicisation. Il s’agit d’observer finement les logiques qui mènent les militants à élaborer leurs énoncés, les régimes de justification déployés, les enjeux et les effets de ces énoncés dans des arènes publiques. De quelle manière les arguments sont-ils construits? Quelles valeurs sont défendues? En quoi les paroles militantes sont-elles légitimées ou délégitimées dans l’espace public? Ces paroles sont également une façon de dire et raconter l’engagement individuel et collectif à partir de formes d’expression singulières (documentaires, témoignages, blogs, etc.). Les contributions réunies dans ce volume étudient les mises en récit des trajectoires militantes, retracent une archéologie de ces discours, et observent les pratiques narratives de personnes engagées dans les controverses environnementales à l’intersection des approches discursive, pragmatique, médiatique et anthropologique
Nutritional and Microbiological Quality of Tiger Nut Tubers (<i>Cyperus esculentus</i>), Derived Plant-Based and Lactic Fermented Beverages
No full textInternational audienceTiger nut (Cyperus esculentus) is a tuber that can be consumed raw or processed into beverages. Its nutritional composition shows a high content of lipid and dietary fiber, close to those of nuts, and a high content of starch, like in other tubers. Tiger nuts also contain high levels of phosphorus, calcium, and phenolic compounds, which contribute to their antioxidant activity. From those characteristics, tiger nuts and derived beverages are particularly relevant to limit food insecurity in regions where the plant can grow. In Europe and United States, the tiger nut derived beverages are of high interest as alternatives to milk and for gluten-free diets. Fermentation or addition of probiotic cultures to tiger nut beverages has proven the ability of lactic acid bacteria to acidify the beverages. Preliminary sensory assays concluded that acceptable products are obtained. In the absence of pasteurization, the safety of tiger nut-based beverages is not warranted. In spite of fermentation, some foodborne pathogens or mycotoxigenic fungi have been observed in fermented beverages. Further studies are required to select a tailored bacterial cocktail which would effectively dominate endogenous flora, preserve bioactive compounds and result in a well-accepted beverage
Long-term coastline monitoring on a coral reef island (Moorea, French Polynesia)
No full textInternational audienceWhile many monitoring programs on coral reefs (for lagoons and outer slopes) exist in the South Pacific, there are no observatories dedicated to monitoring the coastline, a small strip of land and sea upon which many environmental and economic issues coincide. The present study compares the extent of coastline modification at Moorea Island (French Polynesia) between 1977 and 2018. Our coastal monitoring highlighted a strong increase in artificial embankments, and a decrease in beach-dominated coast from 1977 to 2009. From 2009 to 2018, the percentage of embankments have been relatively stable. However, we observed 20% of beach-dominated coast without high vegetation in 2009 and only 10% in 2018. Furthermore, we found that 12% of beach-dominated coast with coarse mud and detrital substrate in 2009 and 22% in 2018. These findings highlighted that anthropogenic factors were principal drivers of coastline changes at Moorea Island. In order to inform conservation and management strategies for coastlines in the South Pacific Islands, it is imperative to conduct ongoing monitoring of coastlines through the creation of dedicated coastline observatories. This work will enhance our understanding of the impact of human-induced environmental changes on this ecologically, economically and culturally important ecosystem
In silico prediction of protein flexibility with local structure approach
No full textInternational audienceFlexibility is an intrinsic essential feature of protein structures, directly linked to their functions. To this day, most of the prediction methods use the crystallographic data (namely B-factors) as the only indicator of protein’s inner flexibility and predicts them as rigid or flexible.PredyFlexy stands differently from other approaches as it relies on the definition of protein flexibility (i) not only taken from crystallographic data, but also (ii) from Root Mean Square Fluctuation (RMSFs) observed in Molecular Dynamics simulations. It also uses a specific representation of protein structures, named Long Structural Prototypes (LSPs). From Position-Specific Scoring Matrix, the 120 LSPs are predicted with a good accuracy and directly used to predict (i) the protein flexibility in three categories (flexible, intermediate and rigid), (ii) the normalized B-factors, (iii) the normalized RMSFs, and (iv) a confidence index. Prediction accuracy among these three classes is equivalent to the best two class prediction methods, while the normalized B-factors and normalized RMSFs have a good correlation with experimental and in silico values. Thus, PredyFlexy is a unique approach, which is of major utility for the scientific community. It support parallelization features and can be run on a local cluster using multiple cores.The entire project is available under an open-source license at http://www.dsimb.inserm.fr/~debrevern/TOOLS/predyflexy_1.3/index.php
The taste of origin in a lady beetle: do males discriminate between females based on cuticular hydrocarbons?
No full textInternational audienceThe Asian lady beetle Harmonia axyridis originates from Asia and has established invasive populations worldwide. Recent population genetic studies trace their invasion routes and demonstrate that bottlenecks in population size have reduced their genetic diversity. Consequently, phenotypical differences are highlighted between native and invasive populations. Among phenotypical traits, cuticular hydrocarbons (CHCs) might reflect the geographical origin of a lady beetle, especially because of their genetic basis. The present study investigates whether (i) the CHC profiles qualitatively and quantitatively differ between females of H. axyridis from native and invasive populations and (ii) males discriminate females from native and invasive populations using CHC profiles. CHCs are solvent-extracted before being quantified and identified by gas chromatography and mass spectrometry. In total, 17 CHCs are detected from female elytra, including six alkanes, three polyunsaturated and eight monounsaturated alkenes. The total quantity of CHCs differs among the populations, with lady beetles from Tai'an (China) displaying higher CHC concentrations than lady beetles from Gembloux (Belgium) and from Beijing (China) populations. Multivariate analyses detect differences in CHC qualitative profiles, with females from Tai'an being different from the two other populations. Finally, behavioural assays show that females originating from the native Tai'an population are less preferred by males, whereas females from the invasive population are mounted more often. The behavioural assays suggest that CHCs are not involved in discrimination of mating partners based on their origin