53161 research outputs found
Sort by
Metformin improves quality of post-thaw canine semen
No full textSperm cryopreservation is an assisted reproductive technique routinely used in canine species for genetic conservation. However, during cryopreservation, the DNA damages are still elevated, limiting the fertilization rate. The present study was conducted to evaluate whether supplementation of canine semen extender with a molecule limiting the metabolic activities can improve the quality of frozen-thawed canine spermatozoa. We used metformin, known to limit the mitochondrial respiratory and limit the oxidative stress. Before and during the freezing procedure, metformin (50µM and 500µM) has been added to the extender. After thawing, sperm exposed to metformin conserved the same viability without alteration in the membrane integrity or acrosome reaction. Interestingly, 50µM metformin improved the sperm motility in comparison to the control, subsequently increasing mitochondrial activity and NAD+ content. In addition, the oxidative stress level was reduced in sperm treated with metformin improving the sperm quality as measured by a different molecular marker. In conclusion, we have shown that metformin is able to improve the quality of frozen-thawed dog semen when it is used during the cryopreservative procedure
Uncovering signatures of DNA methylation in ancient plant remains from patterns of post-mortem DNA damage
No full textThe ultra-short DNA molecules still preserved in archeological remains can provide invaluable genetic information about past individuals, species, and communities within the half to 1-million-year time range. The sequence data are, however, generally affected by post-mortem DNA damage and include specific patterns of nucleotide mis-incorporations, which can help data authentication. Recent work in ancient mammals has shown that such patterns can also help assess past levels of DNA methylation in CpG contexts. Despite pioneering work in barley and sorghum, ancient epigenetic marks have received limited attention in plants and it remains unknown whether ancient epigenetic signatures can be retrieved in any of the three main sequence contexts (CG, CHG, and CHH). To address this question, we extended a statistical methylation score originally proposed to trace cytosine methylation in mammal sequence data to accommodate the three methylation contexts common in plants. We applied this score to a range of tissues (wood, cobs, and grains) and species (oak, maize, and barley), spanning both desiccated and waterlogged archeological samples. Ancient sequence data obtained for USER-treated DNA extracts yielded methylation scores on par with DNA methylation levels of modern organellar and nuclear genomes. At the quantitative level, scores were (1) positively correlated to post-mortem cytosine deamination, and (2) replicated relative contributions of CG, CHG, and CHH contexts to DNA methylation assessed by bisulfite DNA sequencing of modern plant tissues. This demonstrates that genuine DNA methylation signatures can be characterized in ancient plant remains, which opens new avenues for investigating the plant evolutionary response to farming, pollution, epidemics, and changing environmental conditions
A Structure Shaped by Fire, but Also Water: Ecological Consequences of the Variability in Bark Properties Across 31 Species From the Brazilian Cerrado
No full textBark is a structure involved in multiple physiological functions, but which has been traditionally associated with protection against fire. Thus, little is known about how the morpho-anatomical variations of this structure are related to different ecological pressures, especially in tropical savanna species, which are commonly subjected to frequent fire and drought events. Here we evaluated how the structural and functional variations of bark are related to the processes of resilience and resistance to fire, as well as transport and storage of water in 31 native species from the Brazilian Cerrado. Because of their thick bark, none of the trees analyzed were top-killed after a severe fire event. The structural and functional variations of the bark were also associated with water storage and transport, functions related to properties of the inner bark. In fact, species with a thicker and less dense inner bark were the ones that had the highest water contents in the wood, bark, and leaves. Lower bark density was also related to higher stem hydraulic conductivity, carbon assimilation, and growth. Overall, we provide strong evidence that in addition to protection from fire, the relative investment in bark also reflects different strategies of water use and conservation among many Cerrado tree species
Avian pathogenic Escherichia coli (APEC) strain-dependent immunomodulation of respiratory granulocytes and mononuclear phagocytes in CSF1R-reporter transgenic chickens
No full textAvian pathogenic Escherichia coli (APEC) cause severe respiratory and systemic disease in chickens, commonly termed colibacillosis. Early immune responses after initial infection are highly important for the outcome of the infection. In this study, the early interactions between GFP-expressing APEC strains of serotypes O1:K1:H7 and O2:K1:H5 and phagocytic cells in the lung of CSF1R-reporter transgenic chickens were investigated. CSF1R-reporter transgenic chickens express fluorescent protein under the control of elements of the CSF1R promoter and enhancer, such that cells of the myeloid lineage can be visualized in situ and sorted. Chickens were separately inoculated with APEC strains expressing GFP and culled 6 h post-infection. Flow cytometric analysis was performed to phenotype and sort the cells that harbored bacteria in the lung, and the response of the sorted cells was defined by transcriptomic analysis. Both APEC strains were mainly detected in CSF1R-transgeneneg (CSF1R-tgneg) and CSF1R-tglow MHC IIneg MRC1L-Bneg cells and low numbers of APEC were detected in CSF1R-tghigh MHC IIpos MRC1L-Bpos cells. Transcriptomic and flow cytometric analysis identified the APECpos CSF1R-tgneg and CSF1R-tglow cells as heterophils and the APECpos CSF1R-tghigh cells as macrophages and dendritic cells. Both APEC strains induced strong inflammatory responses, however in both CSF1R-tgneg/low and CSF1R-tghigh cells, many immune related pathways were repressed to a greater extent or less activated in birds inoculated with APEC O2-GFP compared to APEC O1-GFP inoculated birds. Comparison of the immune pathways revealed the aryl hydrocarbon receptor (AhR) pathway, IL17 and STAT3 signaling, heterophil recruitment pathways and the acute phase response, are modulated particularly post-APEC O2-GFP inoculation. In contrast to in vivo data, APEC O2-GFP was more invasive in CSF1R-tghigh cells in vitro than APEC O1-GFP and had higher survival rates for up to 6 h post-infection. Our data indicate significant differences in the responses induced by APEC strains of prevalent serotypes, with important implications for the design and interpretation of future studies. Moreover, we show that bacterial invasion and survival in phagocyte populations in vitro is not predictive of events in the chicken lung
The GenTree dendroecological collection, tree-ring and wood density data from seven tree species across Europe
No full textThe dataset presented here was collected by the GenTree project (EU-Horizon 2020), which aims to improve the use of forest genetic resources across Europe by better understanding how trees adapt to their local environment. This dataset of individual tree-core characteristics including ring-width series and whole-core wood density was collected for seven ecologically and economically important European tree species: silver birch (Betula pendula), European beech (Fagus sylvatica), Norway spruce (Picea abies), European black poplar (Populus nigra), maritime pine (Pinus pinaster), Scots pine (Pinus sylvestris), and sessile oak (Quercus petraea). Tree-ring width measurements were obtained from 3600 trees in 142 populations and whole-core wood density was measured for 3098 trees in 125 populations. This dataset covers most of the geographical and climatic range occupied by the selected species. The potential use of it will be highly valuable for assessing ecological and evolutionary responses to environmental conditions as well as for model development and parameterization, to predict adaptability under climate change scenarios
Proceedings of a roundtable event ‘Is communicating the concept of nutrient density important?’
No full textThe British Nutrition Foundation held a 1‐day roundtable event to gather views from a wide range of stakeholders on the relevance and importance of the concept of nutrient density in supporting and motivating people to make healthier dietary choices. The opportunities and barriers associated with the use of this concept were also explored. The roundtable involved experts from research, public health nutrition, dietetics, retail and nutrition science communication, and this report describes the main themes emerging from the discussions. High obesity prevalence rates indicate that, on average, we are consuming too many calories relative to energy requirements; yet, the quality of our diets, with respect to certain vitamins and minerals and fibre, seems to be falling somewhat short of recommendations. Addressing this issue may require a more holistic approach than the current focus on restricting single nutrients prevalent in public health messaging internationally. Most members of the roundtable felt that communicating the concept of nutrient density may help in encouraging healthier food choices and dietary patterns that are higher in nutritional quality. However, while nutrient profiling has been used to guide front‐of‐pack labelling and in restricting the advertising of less healthy foods to children, there is a lack of consensus on the precise definition of a ‘nutrient dense’ food or which nutrients should be used as markers of the ‘healthiness’ of foods/drinks, and the term seems to be poorly understood by consumers and health professionals alike. Therefore, further work is required if tools around this concept are to be developed to try and successfully promote behaviour change
Controlled depolymerization of cellulose by light-driven lytic polysaccharide oxygenases
No full textLytic polysaccharide (mono)oxygenases (LPMOs) perform oxidative cleavage of polysaccharides, and are key enzymes in biomass processing and the global carbon cycle. It has been shown that LPMO reactions may be driven by light, using photosynthetic pigments or photocatalysts, but the mechanism behind this highly attractive catalytic route remains unknown. Here, prompted by the discovery that LPMOs catalyze a peroxygenase reaction more efficiently than a monooxygenase reaction, we revisit these light-driven systems, using an LPMO from Streptomyces coelicolor (ScAA10C) as model cellulolytic enzyme. By using coupled enzymatic assays, we show that H2O2 is produced and necessary for efficient light-driven activity of ScAA10C. Importantly, this activity is achieved without addition of reducing agents and proportional to the light intensity. Overall, the results highlight the importance of controlling fluxes of reactive oxygen species in LPMO reactions and demonstrate the feasibility of light-driven, tunable enzymatic peroxygenation to degrade recalcitrant polysaccharides
STING-dependent paracriny shapes apoptotic priming of breast tumors in response to anti-mitotic treatment
No full textA fascinating but uncharacterized action of antimitotic chemotherapy is to collectively primecancer cells to apoptotic mitochondrial outer membrane permeabilization (MOMP), whileimpacting only on cycling cell subsets. Here, we show that a proapoptotic secretory phe-notype is induced by activation of cGAS/STING in cancer cells that are hit by antimitotictreatment, accumulate micronuclei and maintain mitochondrial integrity despite intrinsicapoptotic pressure. Organotypic cultures of primary human breast tumors and patient-derived xenografts sensitive to paclitaxel exhibit gene expression signatures typical of type IIFN and TNFαexposure. These cytokines induced by cGAS/STING activation trigger NOXAexpression in neighboring cells and render them acutely sensitive to BCL-xL inhibition.cGAS/STING-dependent apoptotic effects are required for paclitaxel response in vivo, andthey are amplified by sequential, but not synchronous, administration of BH3 mimetics.Thus anti-mitotic agents propagate apoptotic priming across heterogeneously sensitivecancer cells through cytosolic DNA sensing pathway-dependent extracellular signals,exploitable by delayed MOMP targeting
Impact of forcing on sublimation simulations for a high mountain catchment in the semiarid Andes
No full textIn the semiarid Andes of Chile, farmers and industry in the cordillera lowlands depend on water from snowmelt, as annual rainfall is insufficient to meet their needs. Despite the importance of snow cover for water resources in this region, understanding of snow depth distribution and snow mass balance is limited. Whilst the effect of wind on snow cover pattern distribution has been assessed, the relative importance of melt versus sublimation has only been studied at the point scale over one catchment. Analyzing relative ablation rates and evaluating uncertainties are critical for understanding snow depth sensitivity to variations in climate and simulating the evolution of the snowpack over a larger area and over time. Using a distributed snowpack model (SnowModel), this study aims to simulate melt and sublimation rates over the instrumented watershed of La Laguna (513 km(2), 3150-5630 ma.s.l., 30 degrees S, 70 degrees W), during two hydrologically contrasting years (i.e., dry vs. wet). The model is calibrated and forced with meteorological data from nine Automatic Weather Stations (AWSs) located in the watershed and atmospheric simulation outputs from the Weather Research and Forecasting (WRF) model. Results of simulations indicate first a large uncertainty in sublimation-to-melt ratios depending on the forcing as the WRF data have a cold bias and overestimate precipitation in this region. These input differences cause a doubling of the sublimation-to-melt ratio using WRF forcing inputs compared to AWS. Therefore, the use of WRF model output in such environments must be carefully adjusted so as to reduce errors caused by inherent bias in the model data. For both input datasets, the simulations indicate a similar sublimation fraction for both study years, but ratios of sublimation to melt vary with elevation as melt rates decrease with elevation due to decreasing temperatures. Finally results indicate that snow persistence during the spring period decreases the ratio of sublimation due to higher melt rates
Genomic DNA PCR analysis to assess xenograft development in mouse mammary gland
No full textThe mouse transplantation model remains the most relevant methodology to assess the functional capacities of mammary cells and is particularly appropriate for investigations regarding mammary stem cells, whatever the species studied. Following xenotransplantation in mice mammary fat pad, the development of the xenograft is commonly evaluated by immunohistology. Here, we present a simple and rapid method to control the species specificity of a xenograft based on genomic DNA PCR amplification. DNA is extracted from the fixed samples intended for histology, thus allowing the reuse of precious samples. Standard and digital droplet PCR (requiring low DNA quantities) methods have been used to make the present method suitable for the analysis of xenotransplanted samples