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UMR
Rennes, France

The presence of hydrogen sulphide H 2S) in sewer systems is a cause of concern to operators: according to recent studies, 40 to 50% of pumping stations are affected; this percentage could reach 70% in rural zones. Four objective reasons can be associated with this phenomenon: - increase in the inter-commune regroupings, lengthening to a significant degree time of transit of the effluents towards a central point of treatment; - average temperature increase of the atmospheric air -the temperature playing a role of accelerator of the biochemical reactions (hydrolysis of the deposits, kinetics biological); - the creation of new cities/districts with the sewer system dimensioned for a future horizon; - the communes (districts) located in touristic zones undergoing a significant variation of occupation between the winter and summer periods. The presence of sulphates in urban wastewater involves, under particular conditions, the formation of hydrogen sulphide. The nuisance generated by the hydrogen sulphide is of four types: olfactive, corrosion of the networks, danger to health, dysfunction of the biological wastewater treatment plant. Well too often, the damage caused by the production of H 2S is a late revealing element of this problem. To avoid this situation, one must approach this phenomenon in a preventive rather than curative way. Source


Recent studies carried out on Gallo-Roman site of Grand (France) illustrate the interest of using integrated methods in characterization of past occupation. Combination of excavations and surface surveying based on non-invasive techniques (such as geophysical surveys, LiDAR, aerial photography) allows a better identification of features. The cross-analysis of all data in GIS improves the global comprehension of the city framework and of its hydrogeological environment. Two case studies are presented: first we compare geophysical maps to speological observations for the detection of drainage galleries; then we show results of excavation and geophysical data in southern district of the agglomeration. Source


Geiger A.,CIRAD - Agricultural Research for Development | Hirtz C.,French National Institute for Agricultural Research | Becue T.,French National Institute for Agricultural Research | Bellard E.,French National Institute for Agricultural Research | And 5 more authors.
BMC Microbiology | Year: 2010

Background. Human African trypanosomiasis is a lethal disease caused by the extracellular parasite Trypanosoma brucei. The proteins secreted by T. brucei inhibit the maturation of dendritic cells and their ability to induce lymphocytic allogenic responses. To better understand the pathogenic process, we combined different approaches to characterize these secreted proteins. Results. Overall, 444 proteins were identified using mass spectrometry, the largest parasite secretome described to date. Functional analysis of these proteins revealed a strong bias toward folding and degradation processes and to a lesser extent toward nucleotide metabolism. These features were shared by different strains of T. brucei, but distinguished the secretome from published T. brucei whole proteome or glycosome. In addition, several proteins had not been previously described in Trypanosoma and some constitute novel potential therapeutic targets or diagnostic markers. Interestingly, a high proportion of these secreted proteins are known to have alternative roles once secreted. Furthermore, bioinformatic analysis showed that a significant proportion of proteins in the secretome lack transit peptide and are probably not secreted through the classical sorting pathway. Membrane vesicles from secretion buffer and infested rat serum were purified on sucrose gradient and electron microscopy pictures have shown 50- to 100-nm vesicles budding from the coated plasma membrane. Mass spectrometry confirmed the presence of Trypanosoma proteins in these microvesicles, showing that an active exocytosis might occur beyond the flagellar pocket. Conclusions. This study brings out several unexpected features of the secreted proteins and opens novel perspectives concerning the survival strategy of Trypanosoma as well as possible ways to control the disease. In addition, concordant lines of evidence support the original hypothesis of the involvement of microvesicle-like bodies in the survival strategy allowing Trypanosoma to exchange proteins at least between parasites and/or to manipulate the host immune system. © 2010 Geiger et al; licensee BioMed Central Ltd. Source


Brienen R.J.W.,University of Leeds | Phillips O.L.,University of Leeds | Feldpausch T.R.,University of Leeds | Feldpausch T.R.,University of Exeter | And 102 more authors.
Nature | Year: 2015

Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models. © 2015 2015 Macmillan Publishers Limited. Source


Toussaint S.,UMR | Reghem E.,UMR | Chotard H.,UMR | Herrel A.,UMR | And 2 more authors.
Journal of Zoology | Year: 2013

The use of the hand in food grasping is a shared characteristic of primates. However, the factors involved in the elaboration of this function remain unclear. Grasping hands may have evolved in an arboreal habitat with narrow branches. Interestingly, grasping may also have an association with different types of feeding such as insect predation, fruit and flower exploitation, or both. No study has tested the importance of substrate diameter and food properties on the use of the hand in food grasping. Yet, both of these parameters likely impose important selective pressures on the origin and evolution of manual grasping strategies in the context of food acquisition. Here, we quantified whether (1) substrate diameter (narrow, wide) and (2) food properties (static, slow moving, fast moving) influence food grasping in a small primate, Microcebus murinus. Our results show that narrow substrates increase the use of hands in prey grasping. The mouth is preferentially used to grasp static food (banana), whereas the hands are preferred to grasp moving prey (mealworm and cricket) regardless of the substrate. Thus, the narrow branch niche may be an important selective pressure on the emergence of manual food grasping in primates, but predation likely also played a key role. © 2013 The Zoological Society of London. Source

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