Prédiction des propriétés de rétention en eau des sols d'un bassin versant à l'aide de fonctions de pédotransfert : influence de la densité apparente et de la teneur en éléments grossiers

L'objectif est d'étudier la qualité de l'estimation des propriétés de rétention en eau faite à l'aide de fonctions de pédotransfert (FPT) pour les sols d'un bassin versant de 250 hectares. Ce bassin versant, situé à proximité de Mantes-la-Jolie, au nord-est de Paris, possède des sols limoneux à limoneux-argileux profonds sur la moitié de sa surface, l'autre moitié correspondant à des sols caillouteux. Après une prospection pédologique détaillée, 15 horizons types ont été définis (Tableau 1), puis 22 unités typologiques de sol (UTS) correspondant à la superposition de plusieurs horizons types et enfin 11 unités cartographiques de sols (UCS) regroupant plusieurs UTS (Tableau 2). Les propriétés de rétention en eau des horizons types ont été déterminées au laboratoire pour 8 valeurs de potentiels variant de –10 à –15000 hPa et, en parallèle, estimées à l'aide des FPT proposées par Hall et al. (1977), Jamagne et al. (1977), Rawls et al. (1982), Vereecken (1989), Bastet (1999) et Bruand et al. (2002) pour des valeurs de potentiel appartenant à ce même domaine. L'aptitude des FPT à rendre compte des variations des propriétés de rétention en eau mesurées pour les horizons types est très variable selon les FPT considérées (Tableau 4). Comme d'autres études l'ont déjà montré (Bastet, 1999, Tietje et Tapkenhinrichs, 1993, Wösten et al., 2001), la proximité géographique de la zone d'étude par rapport à celles ayant servi de base aux FPT et la similitude des matériaux parentaux sont des éléments importants à prendre en compte pour apprécier l'aptitude potentielle de FPT à estimer les propriétés de rétention en eau de sol. Une classification par texture, ou par texture et densité apparente, préalablement à l'établissement de FPT, permet d'améliorer la qualité des estimations. La texture et la densité apparente apparaissent donc comme des grandeurs déterminantes pour estimer correctement les propriétés de rétention en eau des horizons de sols étudiés. Toutefois, la densité apparente à l'échelle de l'horizon peut conduire à prendre en compte un volume de pores qui ne contribuent pas à la réserve en eau du sol, car de trop grande taille, et donc conduire certaines FPT à surestimer largement les valeurs de teneurs en eau. Pour les sols qui possèdent des éléments grossiers, dont la présence n'est pas prise en compte par les FPT, une correction des teneurs en eau mesurées et calculées, visant à les exprimer par rapport à la seule fraction fine (< 2 mm) des horizons, ne permet toutefois à aucune FPT de donner des résultats satisfaisants pour les sols caillouteux. Ces sols caillouteux, le plus souvent peu épais, sont ceux pour lesquels la mesure des propriétés de rétention en eau demeure la plus difficile à obtenir, aucune méthodologie adaptée n'étant disponible à l'heure actuelle

Strongyloides venezuelensis: efeito de antimicrobiano e imunossupressor no curso da infecção em camundongos da linhagem AKR/J

Groups of AKR/J strain of mice infected by Strongyloides venezuelensis and treated with Ceftazidima, Dexametasona or with both drugs concomitantly had been killed on 3rd, 7th and 12th day after infection and their lungs and intestines were processed for histological studies. In lungs of all infected groups, it was verified an inflammatory infiltrated (neutrophils and mononuclear cells) in the third day after the infection. In 7th and 12th day after the infection, the inflammatory reaction becomes reduced in control and antimicrobial treated groups, but not in immunosuppressed animals (with or without antimicrobial treatment). Analysis of the duodenal mucosa confirmed the presence of parasites in all groups of animals. On the 7th day after infection it was observed significant alterations in the small intestine of control (infected) and infected and treated with antimicrobial groups with presence of inflammatory foci, constituted by mononuclear and eosinophils in mucosa, associate to a large amount of parasites, mainly in the region of the epithelium and sub epithelium. Two others groups (infected and immunosuppressed mice with or without antimicrobial), did not present inflammatory process. Goblet cells were less evident in mucosa suggesting a reduction in mucous production. In the 12th day of the infection, the treated with antimicrobial and control groups presented a reduced number of parasites and a discrete inflammatory reaction in the small intestine while the immunosuppressed groups showed more parasites in duodenum. The permanence of the infection by S. venezuelensis in immunosuppressed animals was prolonged in relation to other groups, remaining until the 49th day after infection. The results indicate that the interference of treatments in the population of intestinal microbiota favours the parasitism by Strongyloides venezuelensis.Camundongos da linhagem AKR/J infectados pelo Strongyloides venezuelensis e tratados com Ceftazidima, Dexametasona ou com ambas as drogas foram sacrificados no terceiro, sétimo e décimo segundo dia após infecção. Pulmões e intestino delgado foram processados para histologia. Verificaram-se, nos pulmões dos quatro grupos infectados, infiltrados inflamatórios (neutrófilos e mononucleares) no terceiro dia após a infecção. No sétimo e décimo segundo dia após a infecção, o processo inflamatório se torna reduzido nos animais controle e tratados com antimicrobiano, mas não nos animais imunossuprimidos (com ou sem tratamento com antimicrobiano). A análise da mucosa duodenal confirmou a presença de parasitos em todos os grupos de animais. No 7º dia após a infecção, foram observadas alterações significativas no duodeno dos grupos controle (infectados) e dos infectados e tratados com antimicrobiano, com presença de infiltrado inflamatório, constituído de mononucleares e eosinófilos na mucosa, associada a uma maior quantidade de parasitos, principalmente na região do epitélio e sub-epitélio. Os outros dois grupos (camundongos infectados e imunossuprimidos com ou sem antimicrobiano), não apresentaram processo inflamatório. A mucosa apresentou células caliciformes menos evidentes, sugerindo uma redução de produção de muco. No décimo segundo dia da infecção, os grupos não tratados e tratados apenas com antimicrobiano apresentaram um número reduzido de parasitos e um discreto processo inflamatório no duodeno, enquanto os grupos tratados com imunossupressor (com ou sem antimicrobiano) mostraram presença de um maior número do parasito no duodeno. A permanência da infecção do S. venezuelensis foi mais prolongada nos animais imunossuprimidos em relação aos demais grupos, permanecendo até o 490dia após infecção. Os resultados indicam que a interferência dos tratamentos no equilíbrio da microbiota intestinal favoreceu o parasitismo pelo S. venezuelensis

Development of a World Health Organization International Reference Panel for different genotypes of hepatitis E virus for nucleic acid amplification testing.

Globally, hepatitis E virus (HEV) is a major cause of acute viral hepatitis. Epidemiology and clinical presentation of hepatitis E vary greatly by location and are affected by the HEV genotype. Nucleic acid amplification technique (NAT)-based assays are important for the detection of acute HEV infection as well for monitoring chronic cases of hepatitis E. The aim of the study was to evaluate a panel of samples containing different genotypes of HEV for use in nucleic NAT-based assays. The panel of samples comprises eleven different members including HEV genotype 1a (2 strains), 1e, 2a, 3b, 3c, 3e, 3f, 4c, 4g as well as a human isolate related to rabbit HEV. Each laboratory assayed the panel members directly against the 1 World Health Organization (WHO) International Standard (IS) for HEV RNA (6329/10) which is based upon a genotype 3 a strain. The samples for evaluation were distributed to 24 laboratories from 14 different countries and assayed on three separate days. Of these, 23 participating laboratories returned a total of 32 sets of data; 17 from quantitative assays and 15 from qualitative assays. The assays used consisted of a mixture of in-house developed and commercially available assays. The results showed that all samples were detected consistently by the majority of participants, although in some cases, some samples were detected less efficiently. Based on the results of the collaborative study the panel (code number 8578/13) was established as the "1st International Reference Panel (IRP) for all HEV genotypes for NAT-based assays" by the WHO Expert Committee on Biological Standardization. This IRP will be important for assay validation and ensuring adequate detection of different genotypes and clinically important sub-genotypes of HEV

Role for miR-204 in human pulmonary arterial hypertension

Reduced miR-204 expression facilitates the excessive proliferation and apoptosis resistance of pulmonary artery smooth muscle cells characteristic of human pulmonary arterial hypertension

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost