223 research outputs found

    Lactobacillus rhamnosus lowers zebrafish lipid content by changing gut microbiota and host transcription of genes involved in lipid metabolism.

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    The microbiome plays an important role in lipid metabolism but how the introduction of probiotic communities affects host lipid metabolism is poorly understood. Using a multidisciplinary approach we addressed this knowledge gap using the zebrafish model by coupling high-throughput sequencing with biochemical, molecular and morphological analysis to evaluate the changes in the intestine. Analysis of bacterial 16S libraries revealed that Lactobacillus rhamnosus was able to modulate the gut microbiome of zebrafish larvae, elevating the abundance of Firmicutes sequences and reducing the abundance of Actinobacteria. The gut microbiome changes modulated host lipid processing by inducing transcriptional down-regulation of genes involved in cholesterol and triglycerides metabolism (fit2, agpat4, dgat2, mgll, hnf4α, scap, and cck) concomitantly decreasing total body cholesterol and triglyceride content and increasing fatty acid levels. L. rhamnosus treatment also increased microvilli and enterocyte lengths and decreased lipid droplet size in the intestinal epithelium. These changes resulted in elevated zebrafish larval growth. This integrated system investigation demonstrates probiotic modulation of the gut microbiome, highlights a novel gene network involved in lipid metabolism, provides an insight into how the microbiome regulates molecules involved in lipid metabolism, and reveals a new potential role for L. rhamnosus in the treatment of lipid disorders

    The natural compound climacostol as a prodrug strategy based on pH activation for efficient delivery of cytotoxic small agents

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    We synthesized and characterized MOMO as a new small molecule analog of the cytotoxic natural product climacostol efficiently activated in mild extracellular acidosis. The synthesis of MOMO had a key step in the Wittig olefination for the construction of the carbon-carbon double bond in the alkenyl moiety of climacostol. The possibility of obtaining the target (Z)-alkenyl MOMO derivative in very good yield and without presence of the less active (E)-diastereomer was favored from the methoxymethyl ether (MOM)-protecting group of hydroxyl functions in aromatic ring of climacostol aldehyde intermediate. Of interest, the easy removal of MOM-protecting group in a weakly acidic environment allowed us to obtain a great quantity of climacostol in biologically active (Z)-configuration. Results obtained in free-living ciliates that share the same micro-environment of the climacostol natural producer Climacostomum virens demonstrated that MOMO is well-tolerated in a physiological environment, while its cytotoxicity is rapidly and efficiently triggered at pH 6.3. In addition, the cytostatic vs. cytotoxic effects of acidified-MOMO can be modulated in a dose-dependent manner. In mouse melanoma cells, MOMO displayed a marked pH-sensitivity since its cytotoxic and apoptotic effects become evident only in mild extracellular acidosis. Data also suggested MOMO being preferentially activated in the unique extra-acidic microenvironment that characterizes tumoural cells. Finally, the use of the model organism Drosophila melanogaster fed with an acidic diet supported the efficient activity and oral delivery of MOMO molecule in vivo. MOMO affected oviposition of mating adults and larvae eclosion. Reduced survival of flies was due to lethality during the larval stages while emerging larvae retained their ability to develop into adults. Interestingly, the gut of eclosed larvae exhibited an extended damage (cell death by apoptosis) and the brain tissue was also affected (reduced mitosis), demonstrating that orally activated MOMO efficiently targets different tissues of the developing fly. These results provided a proof-of-concept study on the pH-dependence of MOMO effects. In this respect, MOM-protection emerges as a potential prodrug strategy which deserves to be further investigated for the generation of efficient pH-sensitive small organic molecules as pharmacologically active cytotoxic compounds

    Complement Activity in the Egg Cytosol of Zebrafish Danio rerio: Evidence for the Defense Role of Maternal Complement Components

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    Most fish embryos that develop externally are exposed to an environment full of microbes. How they survive microbial attacks are not understood to date. Here we demonstrated that the egg cytosol prepared from the newly fertilized eggs of zebrafish Danio rerio is capable of killing the Gram-negative bacterium Escherichia coli, via in vitro assay system of the complement activity established. All findings indicate that it is the complement system operating via the alternative pathway that is attributable to the bacteriolytic activity. This is the first report providing the evidence for the functional role of the maternal complement components in fish eggs, paving the way for study of maternal immunity in other organisms whose eggs are fertilized in vitro

    Climacostol reduces tumour progression in a mouse model of melanoma via the p53-dependent intrinsic apoptotic programme

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    Climacostol, a compound produced by the ciliated protozoan Climacostomum virens, displayed cytotoxic properties in vitro. This study demonstrates that it has anti-tumour potential. Climacostol caused a reduction of viability/proliferation of B16-F10 mouse melanoma cells, a rapidly occurring DNA damage, and induced the intrinsic apoptotic pathway characterised by the dissipation of the mitochondrial membrane potential, the translocation of Bax to the mitochondria, the release of Cytochrome c from the mitochondria, and the activation of Caspase 9-dependent cleavage of Caspase 3. The apoptotic mechanism of climacostol was found to rely on the up-regulation of p53 and its targets Noxa and Puma. In vivo analysis of B16-F10 allografts revealed a persistent inhibition of tumour growth rate when melanomas were treated with intra-tumoural injections of climacostol. In addition, it significantly improved the survival of transplanted mice, decreased tumour weight, induced a remarkable reduction of viable cells inside the tumour, activated apoptosis and up-regulated the p53 signalling network. Importantly, climacostol toxicity was more selective against tumour than non-tumour cells. The anti-tumour properties of climacostol and the molecular events associated with its action indicate that it is a powerful agent that may be considered for the design of pro-apoptotic drugs for melanoma therapy

    Controls on natural gas migration in the western Nile Delta fan

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    The aim of this study is to combine petrophysical and geochemical data in order to reconstruct the migration history and pathways of mixed microbial-thermogenic gases drilled on the Nile Delta fan, offshore Egypt. While general interest lies in understanding migration routes, rates and mechanisms special attention is dedicated to understanding (1) the origin of gas in both reservoir and non-reservoir units using chemical and isotopic fingerprints and (2) whether a free gas phase supports relatively rapid leakage via bulk flow in non-reservoir units, both above and below commercial accumulations. The Pilocene section in this study is a classic slope environment comprising channels, mud-rich turbidites, mass transport complexes and hemipelagites. Data from seismic and drilled wells suggest that the channel and levee reservoirs are rarely full to spill, implying either a lack of charge and leakage rates which precludes complete filling of the structures. The provided data set enables a quantitative assessment of gas distribution and its genetic fingerprint in the context of both stratigraphic position and lithology. Data is reported from 25 wells, each provided with a conventional wireline log suite and some with borehole images and high-quality core images. Gas concentration data, plus compositional and isotope data are available for isotubes and headspace gas for both reservoir and non-reservoir units. Small-to-medium scale linear and non-linear depth shifts between different techniques (core recovery, core logging, wireline logging) in conjunction with scale and resolution issues demanded logical/stochastic depth synchronisation and well as harmonisation of signal resolution (typically up-scaling). Accordingly, great care was taken to depth-match core, log and gas data. In general, there is evidence of leaking thermogenic and partly biodegraded gas from the reservoirs under investigation, while some microbial methane appears to be retained in the cap rock. Careful assessment of the maturity of the thermogenic gas charge suggests that in a given structure, maturities are similar throughout the sampled section of underseal, reservoir and top seal. Furthermore, compositional temperature stratification suggests a balance between influx of fresh gas and microbial metabolism rates, supporting the concept of a dynamic charge-leak scenario that is sustaining hydrocarbon fermenting microbial communities in the deep biosphere. It was found that microbial recycling of hydrocarbons at depth enables the identification of diffusive gas mixing pathways in the combined analysis of methane and ethane compositional and isotopic data. The proposed diffusion pattern supports the idea of a widely present coupling between both methanogenic and biodegrading microbial communities that exhibit strong carbon isotopic dis-balances at gas-water contacts (GWC) where nutrient supply is in favour of the biodegrading metabolism. Although the hypothesis of coupled diffusive/microbial gas overprints complies with (1) various literature reports that microbial attack on free gas phases is hindered by restricted physical access and (2) segregative isotope fractionation as a consequence of differences on methane and ethane diffusivity, it is conditional to the nature of gas mixing patterns along borehole trajectories in the context of lithology and pore fluid saturations. Undoubtedly, the ubiquitous presence of microbial gas has consequences for vertical net leakage. As classic empirical wireline models for hydrocarbon saturation (i.e. free gas phase volumetrics) are not suited for clay-dominated cap rock sections, an alternative approach presented in this study is based on total gas (TG) modelling from nuclear logs and its solubility in the formation of brine. The calibrated saturation model is scale-independent and implies that free gas occurs on the most of the clay-dominated non-reservoir sections. However, model resolution is not sufficient to capture the suspected filamentary network of free gas phase within the mudrock pore space that enables relatively rapid leakage via Darcy flow. In an unique attempt to validate manual and thereby subjective lithofacies allocations to core images a subset of rock sample properties such as grain size fractions and porosity were successfully modelled using quantitative core image properties. However, model validity appears to be restricted to clay-rich lithofacies due to both an absence of calibration data for sands and occurrence of abnormally dark sandstone units. Further, an artificial neural network (ANN) was trained to propagate the calibrated core fancies along the entire wireline logged borehole section to set the lithological context for a detailed fluid flow analysis. Reproducibility of input (core) facies by output (wireline) facies is similar to the reproducibility by fellow geoscientists but could not be significantly improved to 60-80% of reliability by reduction of facies types. The study shows that a combination of geochemical data with lithological and petro-physical information generates detailed insights into rates, mechanisms, and pathways of two phase flow through the deep biosphere of gas-charged basins. Vertical, geologically rapid flow through mud-rich sequences is a viable migration route for gas if the influence of cap rock bypass systems (permeable faults, sandstone intrusions, mud volcanoes etc.) is restricted. It was found that an adequate quantification of both thermogenic gas fraction and diffusive gas mixing fingerprints is crucial to identity stratigraphic intervals that are not dominated by advective leakage through the pore space and are consequently bypassed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    Parental rating of sleep in children with attention deficit/hyperactivity disorder

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    Objective: Sleep problems have often been associated with attention deficit/hyperactivity disorder (ADHD). Parents of those with ADHD and children with ADHD report sleep difficulties more frequently than healthy children and their parents. The primary objective of this paper is to describe sleep patterns and problems of 5 to 11-year-old children suffering from ADHD as described by parental reports and sleep questionnaires. Method: The study included 321 children aged 5–11 years (average age 8.4 years); 45 were diagnosed with ADHD, 64 had other psychiatric diagnoses, and 212 were healthy. One hundred and ninety-six of the test subjects were boys and 125 were girls. A semi-structured interview (Kiddie-SADS-PL) was used to DSM-IV diagnose ADHD and comorbidity in the clinical group. Sleep difficulties were rated using a structured sleep questionnaire (Children Sleep Behaviour Scale). Results: Children diagnosed with ADHD had a significantly increased occurrence of sleep problems. Difficulties relating to bedtime and unsettled sleep were significantly more frequent in the ADHD group than in the other groups. Children with ADHD showed prolonged sleep onset latency, but no difference was shown regarding numbers of awakenings per night and total sleep time per night. Comorbid oppositional defiant disorder appeared not to have an added effect on problematic behaviour around bedtime. Conclusion: Parents of children with ADHD report that their children do not sleep properly more often than other parents. The ADHD group report problems with bedtime resistance, problems with sleep onset latency, unsettled sleep and nightmares more often than the control groups. It may therefore be relevant for clinicians to initiate a closer examination of those cases reporting sleep difficulties

    Dysfunctional autophagy induced by the pro-apoptotic natural compound climacostol in tumour cells

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    Autophagy occurs at a basal level in all eukaryotic cells and may support cell survival or activate death pathways. Due to its pathophysiologic significance, the autophagic machinery is a promising target for the development of multiple approaches for anti-neoplastic agents. We have recently described the cytotoxic and pro-apoptotic mechanisms, targeting the tumour suppressor p53, of climacostol, a natural product of the ciliated protozoan Climacostomum virens. We report here on how climacostol regulates autophagy and the involvement of p53-dependent mechanisms. Using both in vitro and in vivo techniques, we show that climacostol potently and selectively impairs autophagy in multiple tumour cells that are committed to die by apoptosis. In particular, in B16-F10 mouse melanomas climacostol exerts a marked and sustained accumulation of autophagosomes as the result of dysfunctional autophagic degradation. We also provide mechanistic insights showing that climacostol affects autophagosome turnover via p53-AMPK axis, although the mTOR pathway unrelated to p53 levels plays a role. In particular, climacostol activated p53 inducing the upregulation of p53 protein levels in the nuclei through effects on p53 stability at translational level, as for instance the phosphorylation at Ser15 site. Noteworthy, AMPK\u3b1 activation was the major responsible of climacostol-induced autophagy disruption in the absence of a key role regulating cell death, thus indicating that climacostol effects on autophagy and apoptosis are two separate events, which may act independently on life/death decisions of the cell. Since the activation of p53 system is at the molecular crossroad regulating both the anti-autophagic action of climacostol and its role in the apoptosis induction, it might be important to explore the dual targeting of autophagy and apoptosis with agents acting on p53 for the selective killing of tumours. These findings also suggest the efficacy of ciliate bioactive molecules to identify novel lead compounds in drug discovery and development

    TGF-β1 Exerts Opposing Effects on Grass Carp Leukocytes: Implication in Teleost Immunity, Receptor Signaling and Potential Self-Regulatory Mechanisms

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    In fish immunity, the regulatory role of transforming growth factor-β1 (TGF-β1) has not been fully characterized. Here we examined the immunoregulatory effects of TGF-β1 in grass carp peripheral blood leukocytes (PBL) and head kidney leukocytes (HKL). It is interesting that TGF-β1 consistently stimulated the cell viability and the mRNA levels of pro-inflammatory cytokines (Tnfα and Ifnγ) and T/B cell markers [Cd4-like (Cd4l), Cd8α, Cd8β and Igμ] in PBL, which contrasted with its inhibitory tone in HKL. Further studies showed that grass carp TGF-β1 type I receptor, activin receptor-like kinase 5 (ALK5), was indispensable for the immunoregulatory effects of TGF-β1 in PBL and HKL. Notably, TGF-β1 persistently attenuated ALK5 expression, whereas immunoneutralization of endogenous grass carp TGF-β1 could increase ALK5 mRNA and protein levels. It is consistent with the observation that TGF-β1 decreased the number of ALK5+ leukocytes in PBL and HKL, revealing a negative regulation of TGF-β1 signaling at the receptor level. Moreover, transient treatment with TGF-β1 for 24 h was sufficient to induce similar cellular responses compared with the continuous treatment. This indicated a possible mechanism by which TGF-β1 triggered the down-regulation of ALK5 mRNA and protein, leading to the desensitization of grass carp leukocytes toward TGF-β1. Accordingly, our data revealed a dual role of TGF-β1 in teleost immunity in which it can serve as a positive or negative control device and provided additional mechanistic insights as to how TGF-β1 controls its signaling in vertebrate leukocytes

    Probiotic supplementation influences the diversity of the intestinal microbiota during early stages of farmed Senegalese sole (Solea senegalensis, Kaup, 1858)

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    Ingestion of bacteria at early stages results in establishment of a primary intestinal microbiota which likely undergoes several stages along fish life. The role of this intestinal microbiota regulating body functions is crucial for larval development. Probiotics have been proved to modulate this microbiota and exert antagonistic effects against fish pathogens. In the present study, we aimed to determine bacterial diversity along different developmental stages of farmed Senegalese sole (Solea senegalensis) after feeding probiotic (Shewanella putrefaciens Pdp11) supplemented diet for a short period (10–30 days after hatching, DAH). Intestinal lumen contents of sole larvae fed control and probiotic diets were collected at 23, 56, 87, and 119 DAH and DNA was amplified using 16S rDNA bacterial domain-specific primers. Amplicons obtained were separated by denaturing gradient gel electrophoresis (DGGE), cloned, and resulting sequences compared to sequences in GenBank. Results suggest that Shewanella putrefaciens Pdp11 induces a modulation of the dominant bacterial taxa of the intestinal microbiota from 23 DAH. DGGE patterns of larvae fed the probiotic diet showed a core of bands related to Lactobacillus helveticus, Pseudomonas acephalitica, Vibrio parahaemolyticus,and Shewanella genus, together with increased Vibri o genus presence. In addition, decreased number of clones related to Photobacterium damselae subsp piscicida at 23 and 56 DAH was observed in probiotic-fed larvae. A band corresponding to Shewanella putrefaciens Pdp11 was sequenced as predominant from 23 to 119 DAH samples, confirming the colonization by the probiotics. Microbiota modulation obtained via probiotics addition emerges as an effective tool to improve Solea senegalensis larviculture.En prens
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