245 research outputs found
Observations sur la reproduction artificielle de l'ombre commun (Thymallus thymallus)
National audienceVarious observations and results of experiments carried out in the hatchery of the "Conseil Supérieur de la Pêche" in Augerolles are presented, concerning the technics of artificials pawning adapted to the physiology of grayling . It is shown that th e physiological characteristics are nearly t he same as those of brown trout . Nevertheless highs ensitivity to low temperatures reduces the speed of the finaloocyte maturation. These observations and experiments lead the authors to give practical recommendations.Diverses observations et résultats d'expériences réalisées à la Salmoniculture du Conseil Supérieur de la Pêche à Augerolles sont présentés, concernant les techniques de reproduction artificielle adaptées à la physiologie de l'Ombre commun. Les caractéristiques physiologiques mises en évidence sont proches de celles de la Truite avec cependant une sensibilité accrue aux basses températures , qui peuvent ralentir très fortement la fin de la maturation ovocytaire. Ces observations et expériences conduisent les auteurs à formuler un certain nombre de conseils pratiques
HETEROFOR 1.0: A spatially explicit model for exploring the response of structurally complex forests to uncertain future conditions-Part 2: Phenology and water cycle
Climate change affects forest growth in numerous and sometimes opposite ways, and the resulting trend is often difficult to predict for a given site. Integrating and structuring the knowledge gained from the monitoring and experimental studies into process-based models is an interesting approach to predict the response of forest ecosystems to climate change. While the first generation of models operates at stand level, one now needs spatially explicit individual-based approaches in order to account for individual variability, local environment modification and tree adaptive behaviour in mixed and uneven-Aged forests that are supposed to be more resilient under stressful conditions. The local environment of a tree is strongly influenced by the neighbouring trees, which modify the resource level through positive and negative interactions with the target tree. Among other things, drought stress and vegetation period length vary with tree size and crown position within the canopy. In this paper, we describe the phenology and water balance modules integrated in the tree growth model HETEROFOR (HETEROgenous FORest) and evaluate them on six heterogeneous sessile oak and European beech stands with different levels of mixing and development stages and installed on various soil types. More precisely, we assess the ability of the model to reproduce key phenological processes (budburst, leaf development, yellowing and fall) as well as water fluxes. Two two-phase models differing regarding their response function to temperature during the chilling period (optimum and sigmoid functions) and a simplified one-phase model are. used to predict budburst date. The two-phase model with the optimum function is the least biased (overestimation of 2.46 d), while the one-phase model best accounts for the interannual variability (Pearson's r D 0:68). For the leaf development, yellowing and fall, predictions and observations are in accordance. Regarding the water balance module, the predicted throughfall is also in close agreement with the measurements (Pearson's r D 0:856; biasD 1:3 %), and the soil water dynamics across the year are well reproduced for all the study sites (Pearson's r was between 0.893 and 0.950, and bias was between 1:81 and 9:33 %). The model also reproduced well the individual transpiration for sessile oak and European beech, with similar performances at the tree and stand scale (Pearson's r of 0.84 0.85 for sessile oak and 0.88 0.89 for European beech). The good results of the model assessment will allow us to use it reliably in projection studies to evaluate the impact of climate change on tree growth in structurally complex stands and test various management strategies to improve forest resilience. © 2020 Author(s)
Estimating soil hydraulic properties using L-band radiometer and ground-penetrating radar
peer reviewedIn this study, we experimentally analyze the feasibility of estimating the soil hydraulic properties from L-band radiometer and ground-penetrating radar (GPR) data. L-band radiometer and ultrawideband off-ground GPR measurements were performed above a sand box in hydrostatic equilibrium with a water table located at different depths. The results of the inversions showed that the radar and radiometer signals contain sufficient information to estimate the soil water retention curve and its related hydraulic parameters with a relatively good accuracy compared to time-domain reflectometry estimates. However, an accurate estimation of the hydraulic parameters was only obtained by considering the saturated water content parameter as known during the inversion. © 2012 IEEE
Modeling soil organic carbon dynamics in temperate forests with Yasso07
In a context of global changes, modeling and predicting the
dynamics of soil carbon stocks (CSs) in forest ecosystems are vital but challenging.
Yasso07 is considered to be one of the most promising models for such a purpose. We
examine the accuracy of its prediction of soil carbon dynamics over the whole
French metropolitan territory at a decennial timescale.
We used data from 101 sites in the RENECOFOR network, which encompasses most
of the French temperate forests. These data include (i)Â the quantity of
above-ground litterfall from 1994 to 2008, measured yearly, and (ii)Â the soil
CSs measured twice at an interval of approximately 15Â years (once
in the early 1990s and around 2010). We used Yasso07 to simulate the annual
changes in carbon stocks (ACCs; in tC ha−1 yr−1) for each site and then
compared the estimates with actual recorded data. We carried out
meta-analyses to reveal the variability in litter biochemistry in different
tree organs for conifers and broadleaves. We also performed sensitivity
analyses to explore Yasso07's sensitivity to annual litter inputs and model
initialization settings.
At the national level, the simulated ACCs
(+0.00±0.07 tC ha−1 yr−1, mean ± SE) were of the same
order of magnitude as the observed ones (+0.34±0.06 tC ha−1 yr−1). However, the correlation between predicted
and measured ACCs remained weak (R2<0.1). There was significant
overestimation for broadleaved stands and underestimation for coniferous
sites. Sensitivity analyses showed that the final estimated CS was
strongly affected by settings in the model initialization, including litter
and soil carbon quantity and quality and also by simulation length. Carbon
quality set with the partial steady-state assumption gave a better fit than
the model with the complete steady-state assumption.
With Yasso07 as the support model, we showed that there is currently a
bottleneck in soil carbon modeling and prediction due to a lack of
knowledge or data on soil carbon quality and fine-root quantity in the
litter.</p
Reporte del vampiro de patas peludas Diphylla ecaudata Spix, 1823 (Chiroptera: Desmodontinae) para el Chocó biogeográfico colombiano
It is reported a new record of the hairy-legged vampire Diphylla ecaudata (SPIX, 1823) in the Choco region of Colombia, of which are known only few studies in the country, registered in the departments of Magdalena (1900), Vaupés (1966), Meta (1970), Caquetá (1999) y Amazonas (2016). This registry is based on two specimens that were properly analyzed and due to its curiosity, discusses the available information on this species in the country in terms of its distribution and ecology, based on specimens in collections and existing reports. This log helps fill a void of the known geographic distribution of the species in the country deposited in the Teriologica Scientific Collection Research Group on Management and Wildlife Management of the Chocó of the Technological University of Chocó (ColTer-Choco). This report extends the geographic distribution until the department of Choco, in contraendose to 464.794 km some of the record closest in Magdalena, adding the Tropical Dry Forest Ecosystem (BST) to habitats that occurred for the species. Due to its curiosity, discusses the available information on this species in the country in terms of its distribution and ecology, based on specimens in collections and existing reports. This log helps fill a void of the known geographic distribution of the species in the country.Se reporta un nuevo registro del vampiro de patas peludas Diphylla ecaudata (SPIX, 1823) en el Chocó Biogeográfico colombiano, del que solo se conocen pocos estudios en el paÃs, registrada en los departamentos de Magdalena (1900), Vaupés (1966), Meta (1970), Caquetá (1999), Casanare (2013) y Amazonas (2016). Este registro se basa en dos especÃmenes que fueron debidamente analizados y depositados en la Colección CientÃfica Teriológica del Grupo de Investigación en Manejo y Gestion de la Vida Silvestre del Chocó de la Universidad Tecnológica del Chocó (ColTer-Chocó). Este reporte amplÃa la distribución geográfica hasta el departamento del Chocó, en contraendose a 464.794 km aproximadamente del registro más cercano en el Magdalena, adicionando el ecosistema Bosque Seco Tropical (BST) a los hábitats ocurridos por la especie. Debido a su curiosidad, se discute la información disponible sobre esta especie en el paÃs en términos de su distribución y ecologÃa, a partir de ejemplares en colecciones y reportes existentes. Este registro ayuda a llenar un vacÃo de la distribución geográfica conocida de la especie en el paÃs
A Mild Form of SLC29A3 Disorder: A Frameshift Deletion Leads to the Paradoxical Translation of an Otherwise Noncoding mRNA Splice Variant
We investigated two siblings with granulomatous histiocytosis prominent in the nasal area, mimicking rhinoscleroma and Rosai-Dorfman syndrome. Genome-wide linkage analysis and whole-exome sequencing identified a homozygous frameshift deletion in SLC29A3, which encodes human equilibrative nucleoside transporter-3 (hENT3). Germline mutations in SLC29A3 have been reported in rare patients with a wide range of overlapping clinical features and inherited disorders including H syndrome, pigmented hypertrichosis with insulin-dependent diabetes, and Faisalabad histiocytosis. With the exception of insulin-dependent diabetes and mild finger and toe contractures in one sibling, the two patients with nasal granulomatous histiocytosis studied here displayed none of the many SLC29A3-associated phenotypes. This mild clinical phenotype probably results from a remarkable genetic mechanism. The SLC29A3 frameshift deletion prevents the expression of the normally coding transcripts. It instead leads to the translation, expression, and function of an otherwise noncoding, out-of-frame mRNA splice variant lacking exon 3 that is eliminated by nonsense-mediated mRNA decay (NMD) in healthy individuals. The mutated isoform differs from the wild-type hENT3 by the modification of 20 residues in exon 2 and the removal of another 28 amino acids in exon 3, which include the second transmembrane domain. As a result, this new isoform displays some functional activity. This mechanism probably accounts for the narrow and mild clinical phenotype of the patients. This study highlights the ‘rescue’ role played by a normally noncoding mRNA splice variant of SLC29A3, uncovering a new mechanism by which frameshift mutations can be hypomorphic
Management Impacts on Forest Floor and Soil Organic Carbon in Northern Temperate Forests of the US
<p>Abstract</p> <p>Background</p> <p>The role of forests in the global carbon cycle has been the subject of a great deal of research recently, but the impact of management practices on forest soil dynamics at the stand level has received less attention. This study used six forest management experimental sites in five northern states of the US to investigate the effects of silvicultural treatments (light thinning, heavy thinning, and clearcutting) on forest floor and soil carbon pools.</p> <p>Results</p> <p>No overall trend was found between forest floor carbon stocks in stands subjected to partial or complete harvest treatments. A few sites had larger stocks in control plots, although estimates were often highly variable. Forest floor carbon pools did show a trend of increasing values from southern to northern sites. Surface soil (0-5 cm) organic carbon content and concentration were similar between treated and untreated plots. Overall soil carbon (0-20 cm) pool size was not significantly different from control values in sites treated with partial or complete harvests. No geographic trends were evident for any of the soil properties examined.</p> <p>Conclusions</p> <p>Results indicate that it is unlikely that mineral soil carbon stocks are adversely affected by typical management practices as applied in northern hardwood forests in the US; however, the findings suggest that the forest floor carbon pool may be susceptible to loss.</p
Linking satellite derived LAI patterns with subsoil heterogeneity using large-scale ground-based electromagnetic induction measurements
Long-COVID cognitive impairments and reproductive hormone deficits in men may stem from GnRH neuronal death
BACKGROUND: We have recently demonstrated a causal link between loss of gonadotropin-releasing hormone (GnRH), the master molecule regulating reproduction, and cognitive deficits during pathological aging, including Down syndrome and Alzheimer's disease. Olfactory and cognitive alterations, which persist in some COVID-19 patients, and long-term hypotestosteronaemia in SARS-CoV-2-infected men are also reminiscent of the consequences of deficient GnRH, suggesting that GnRH system neuroinvasion could underlie certain post-COVID symptoms and thus lead to accelerated or exacerbated cognitive decline. METHODS: We explored the hormonal profile of COVID-19 patients and targets of SARS-CoV-2 infection in post-mortem patient brains and human fetal tissue. FINDINGS: We found that persistent hypotestosteronaemia in some men could indeed be of hypothalamic origin, favouring post-COVID cognitive or neurological symptoms, and that changes in testosterone levels and body weight over time were inversely correlated. Infection of olfactory sensory neurons and multifunctional hypothalamic glia called tanycytes highlighted at least two viable neuroinvasion routes. Furthermore, GnRH neurons themselves were dying in all patient brains studied, dramatically reducing GnRH expression. Human fetal olfactory and vomeronasal epithelia, from which GnRH neurons arise, and fetal GnRH neurons also appeared susceptible to infection. INTERPRETATION: Putative GnRH neuron and tanycyte dysfunction following SARS-CoV-2 neuroinvasion could be responsible for serious reproductive, metabolic, and mental health consequences in long-COVID and lead to an increased risk of neurodevelopmental and neurodegenerative pathologies over time in all age groups. FUNDING: European Research Council (ERC) grant agreements No 810331, No 725149, No 804236, the European Union Horizon 2020 research and innovation program No 847941, the Fondation pour la Recherche Médicale (FRM) and the Agence Nationale de la Recherche en Santé (ANRS) No ECTZ200878 Long Covid 2021 ANRS0167 SIGNAL, Agence Nationale de la recherche (ANR) grant agreements No ANR-19-CE16-0021-02, No ANR-11-LABEX-0009, No. ANR-10-LABEX-0046, No. ANR-16-IDEX-0004, Inserm Cross-Cutting Scientific Program HuDeCA, the CHU Lille Bonus H, the UK Medical Research Council (MRC) and National Institute of Health and care Research (NIHR)
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