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See detailPerinatal programming of depressive-like behavior by inflammation in adult offspring mice whose mothers were fed polluted eels: Gender selective effects
Soualed, Nidhal; Dridi, Imen; Eppe, Gauthier ULg et al

in Brain, Behavior & Immunity (in press)

Several lines of evidence indicate that early-life inflammation may predispose to mental illness, including depression, in later-life. We investigated the impact of perinatal exposure to polluted eels on ... [more ▼]

Several lines of evidence indicate that early-life inflammation may predispose to mental illness, including depression, in later-life. We investigated the impact of perinatal exposure to polluted eels on neonatal, postnatal, and adult brain inflammation, and on the resignation behavior of male and female adult offspring mice. The effects of maternal standard diet (laboratory food) were compared to the same diet enriched with low, intermediate, or highly polluted eels. Brain inflammatory markers including cytokines were assessed in offspring mice on the day of birth (i.e., on the postnatal day–PND 1), upon weaning (PND 21) and at adulthood (PND 100). Plasma myeloperoxidase and corticosterone levels were evaluated at PND 100. Immobility behavior of offspring was assessed in adulthood (i.e., at PNDs 95–100), using the tail suspension and forced swimming tests. Chronic brain inflammation was found in male and female offspring mice compared to controls, as assessed at PNDs 1, 21, and 100. The level of myeloperoxidase was found to be significantly higher in both adult males and females vs. control offspring. However, high corticosterone levels were only found in male offspring mice that were perinatally exposed to eels, suggesting a gender-selective dysregulation of the adult hypothalamicpituitaryadrenal (HPA) axis. Gender-specific differences were also detected in adulthood in regard to offspring resignation behavior. Thus, compared to controls, males, but not females, whose mothers were fed eels during pregnancy and lactation exhibited a depressive-like behavior in adult age in both behavioral models of depression. Depressive symptoms were more pronounced in male mice perinatally exposed to either intermediate or highly polluted eels than those exposed to only lowly polluted eels. Our results indicate that early-life inflammatory insult is a plausible causative factor that induce the depressive phenotype exhibited by male adult offspring mice, most likely through a gender-specific HPA axis enhanced activation. [less ▲]

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See detailMorphology of the filtration apparatus of three planktivorous fishes and relation with ingested anthropogenic particles
Collard, France ULg; Gilbert, Bernard ULg; Eppe, Gauthier ULg et al

in Marine Pollution Bulletin (2017)

Anthropogenic particles (APs), including microplastics, are ingested by a wide variety of marine organisms. Exposure of Clupeiformes (e.g. herrings, anchovies, sardines) is poorly studied despite their ... [more ▼]

Anthropogenic particles (APs), including microplastics, are ingested by a wide variety of marine organisms. Exposure of Clupeiformes (e.g. herrings, anchovies, sardines) is poorly studied despite their economic and ecological importance. This study aims to describe the morphology of the filtration apparatus of three wild-caught Clupeiformes (Sardina pilchardus, Clupea harengus and Engraulis encrasicolus) and to relate the results to ingested APs. Consequently, the species with the more efficient filtration apparatus will be more likely to ingest APs. We hypothesized that sardines were the most exposed species. The filtration area and particle retention threshold were determined in the three species, with sardines displaying the highest filtration area and the closest gill rakers. Sardines ingested more fibers and smaller fragments, confirming that it is the most efficient filtering species. These two results lead to the conclusion that, among the three studied, the sardine is the species most exposed to APs. [less ▲]

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See detailSpatial variation in the accumulation of POPs and mercury in bottlenose dolphins of the Lower Florida Keys and the coastal Everglades (South Florida)
Damseaux, France ULg; Kiszka, J.; Heithaus, M.R. et al

in Environmental Pollution (2017), 220

The bottlenose dolphin (Tursiops truncatus) is an upper trophic level predator and the most common cetacean species found in nearshore waters of southern Florida, including the Lower Florida Keys (LFK ... [more ▼]

The bottlenose dolphin (Tursiops truncatus) is an upper trophic level predator and the most common cetacean species found in nearshore waters of southern Florida, including the Lower Florida Keys (LFK) and the Florida Coastal Everglades (FCE). The objective of this study was to assess contamination levels of total mercury (T-Hg) in skin and persistent organic pollutants (PCBs, PBDEs, DDXs, HCHs, HCB, Σ PCDD/Fs and Σ DL-PCBs) in blubber samples of bottlenose dolphins from LFK (n = 27) and FCE (n = 24). PCBs were the major class of compounds found in bottlenose dolphin blubber and were higher in individuals from LFK (Σ 6 PCBs LFK males: 13421 ± 7730 ng.g-1 lipids, Σ 6 PCBs LFK females: 9683 ± 19007 ng.g-1 lipids) than from FCE (Σ 6 PCBs FCE males: 5638 ng.g-1 ± 3627 lipids, Σ 6 PCBs FCE females: 1427 ± 908 ng.g-1 lipids). These levels were lower than previously published data from the southeastern USA. The Σ DL-PCBs were the most prevalent pollutants of dioxin and dioxin like compounds (Σ DL-PCBs LFK: 739 ng.g-1 lipids, Σ DL-PCBs FCE: 183 ng.g-1 lipids) since PCDD/F concentrations were low for both locations (mean 0.1 ng.g-1 lipids for LFK and FCE dolphins). The toxicity equivalences of PCDD/Fs and DL-PCBs expressed as TEQ in LFK and FCE dolphins is mainly expressed by DL-PCBs (81% LFK - 65% FCE). T-Hg concentrations in skin were significantly higher in FCE (FCE median 9314 ng.g-1 dw) compared to LFK dolphins (LFK median 2941 ng.g-1 dw). These bottlenose dolphins concentrations are the highest recorded in the southeastern USA, and may be explained, at least partially, by the biogeochemistry of the Everglades and mangrove sedimentary habitats that create favourable conditions for the retention of mercury and make it available at high concentrations for aquatic predators. [less ▲]

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See detailEffect of the Extraction Technique, Heating Time and Cryogenic Grinding (N2 at -196°C) on the Composition of Cumin Seeds Volatile Oil
Mékaoui, R; Benkaci-Ali, Farid; Scholl, Georges ULg et al

in Journal of Essential Oil-Bearing Plants [=JEOBP] (2016), 19(8), 1903-1919

Two techniques of extraction of essential oils (Steam distillation assisted by microwave (SDAM) and hydrodistillation assisted by microwave (HDAM)) are respectively advanced steam distillation (SD) and ... [more ▼]

Two techniques of extraction of essential oils (Steam distillation assisted by microwave (SDAM) and hydrodistillation assisted by microwave (HDAM)) are respectively advanced steam distillation (SD) and hydrodistillation techniques (HD), in which a microwave oven is used in the extraction process. They are considered as accelerated techniques extraction performed at atmospheric pressure. The cryogrinding (CG) showed a difference on the yields and aromatic profile comparing to the sample grinding. Isolation and concentration of volatile compounds are performed by a single stage for the extraction of volatile oil from Algerian (Sahara) Cuminum cyminum seeds (CCS). The chemical composition of the essential oil of this plant as a function of extraction time was also studied. The major components and family classes showed a significant variation with the extraction time. Gas chromatography (GC), GCxGC-mass spectrometry (GCxGC-MS)] were utilised for qualitative and quantitative analysis of essential oils extracted by these two methods. The major compounds are cumin aldehyde (HDAM-CG: 20.50-53.35 %, SDAM-CG: 21.68 66.6 %), p-cymene (HDAM-CG: 14.1-37.54 %, SDAM-CG: 6.06-20.18 %), β-pinene (HDAM-CG: 4.53-14.74 %, SDAM-CG: 4.3-32.65 %) and γ-terpinene (HDAM-CG: 1.26-14.70 %, SDAM-CG: 5.13-18.23 %). [less ▲]

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See detailIntegrated microfluidic device for the synthesis of SERS substrates
Emonds-Alt, Gauthier ULg; Malherbe, Cédric ULg; Monbaliu, Jean-Christophe ULg et al

Poster (2016, December 19)

The goal of this work is to develop a quantitative analytical method for the glyphosate and its major metabolite the aminomethylphosphonic acid (AMPA) by coupling microfluidics with surface enhanced Raman ... [more ▼]

The goal of this work is to develop a quantitative analytical method for the glyphosate and its major metabolite the aminomethylphosphonic acid (AMPA) by coupling microfluidics with surface enhanced Raman spectroscopy (SERS). This work is divided into 4 axes : (a) bimetallic nanoparticles synthesis in a microreactor, (b) nanoparticles functionnalisation, (c) SERS quantification of glyphosate/AMPA and (d) miniature prototype development composed of axes a to c. The first section aims at the synthesis of bimetallic nanoparticles (Au-Ag, Au-Cu and Ag-Cu) in a microfluidic device. This microfluidic device integrates a first section for the synthesis of monometallic nanoparticles (core) and a second section for the reductive deposition of a second metal (shell). The second axe of this work deals with the functionnalisation of nanoparticles to improve the selectivity of this method for the selected analytes. Two types of functionnalisation are studied : PEGylation (a) with multi-arm PEG ending with -SH and/or (b) with linear heterobifunctionnal PEG. The third axe consists in measuring quantitatively glyphosate and AMPA in different matrices, such as water, urine and fruit juice. Finally, the forth axe deals with the development of a portable detection system to perform on-site analysis. This prototype integrates the microfluidic device for nanoparticles synthesis, their functionnalisation, an injection port followed by a mixing section for the sample and an integrated Raman spectrometer for in-line analysis. [less ▲]

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See detailRaman imaging for diagnostic application
Malherbe, Cédric ULg; Gilbert, Bernard ULg; Eppe, Gauthier ULg

Poster (2016, December 19)

Specific dynamic biochemical compositions and molecular structures characterise healthy cells and tissues. This also stands for pathologies or cellular abnormalities which are accompanied by biochemical ... [more ▼]

Specific dynamic biochemical compositions and molecular structures characterise healthy cells and tissues. This also stands for pathologies or cellular abnormalities which are accompanied by biochemical and molecular changes. Raman spectroscopy can provide unique inputs to correlate the molecular composition and its variations with the diagnosis. In addition, the presence of metal nanoparticles in the molecule vicinity induces a remarkable enhancement (up to 1000000 times) of the Raman signal of small molecules (known as SERS effect). It opens towards applications in the field of trace analysis. In preparation for clinical applications, we evaluate, by Raman mapping, the signal detected from a SERS target deposited on solid state support. [less ▲]

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See detailSpectroscopie Raman: Application à l'Etude de Minéraux
Malherbe, Cédric ULg; Eppe, Gauthier ULg

Conference given outside the academic context (2016)

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See detailIntegrated microfluidic device for in line SERS detection for glyphosate and related metabolites
Emonds-Alt, Gauthier ULg; Malherbe, Cédric ULg; Monbaliu, Jean-Christophe ULg et al

Poster (2016, July 07)

The goal of this work is to develop a quantitative analytical method for the glyphosate and its major metabolite the aminomethylphosphonic acid (AMPA) by coupling microfluidics with surface enhanced Raman ... [more ▼]

The goal of this work is to develop a quantitative analytical method for the glyphosate and its major metabolite the aminomethylphosphonic acid (AMPA) by coupling microfluidics with surface enhanced Raman spectroscopy (SERS). This work is divided into 4 axes : (a) bimetallic nanoparticles synthesis in a microreactor, (b) nanoparticles functionnalisation, (c) SERS quantification of glyphosate/AMPA and (d) miniature prototype development composed of axes a to c. The first section aims at the synthesis of bimetallic nanoparticles (Au-Ag, Au-Cu and Ag-Cu) in a microfluidic device. This microfluidic device integrates a first section for the synthesis of monometallic nanoparticles (core) and a second section for the reductive deposition of a second metal (shell). The second axe of this work deals with the functionnalisation of nanoparticles to improve the selectivity of this method for the selected analytes. Two types of functionnalisation are studied : PEGylation (a) with multi-arm PEG ending with -SH and/or (b) with linear heterobifunctionnal PEG. The third axe consists in measuring quantitatively glyphosate and AMPA in different matrices, such as water, urine and fruit juice. Finally, the forth axe deals with the development of a portable detection system to perform on-site analysis. This prototype integrates the microfluidic device for nanoparticles synthesis, their functionnalisation, an injection port followed by a mixing section for the sample and an integrated Raman spectrometer for in-line analysis. [less ▲]

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See detailDevelopment and optimization of a TD-GC/MS methodology for detection and quantifi cation of furan released in air using of an experimental design.
Alsafra, Zouheir ULg; Scholl, Georges ULg; Romain et al

Poster (2016, July 07)

In the aim of understanding the way in which human is exposed to furan present in the air of an occupational area, an analytical method of Thermal desorption-gas chromatography/Mass spectrometry (TD-GC/MS ... [more ▼]

In the aim of understanding the way in which human is exposed to furan present in the air of an occupational area, an analytical method of Thermal desorption-gas chromatography/Mass spectrometry (TD-GC/MS) has been developed and optimized using a Plackett–Burman experimental design. This method was then used to study the phenomena of diffusion of furan released in air from a contamination source. This source of furan is simply a coffee machine located in a closed controlled room. Results show that furan concentration increases quickly over time after turning on the coffee machine until reaching a maxima. Then it starts to decrease slowly. On the other hand, concentration of furan seems to be identical everywhere in the conditioned room in each moment. [less ▲]

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See detailEffects of protein source and cooking procedure on intestinal microbiota and on fermentation end-products in rats
POELAERT, Christine ULg; Despret, Xavier; Portetelle, Daniel ULg et al

Poster (2016, June)

Animal and plant proteins are major proteins sources in the human diet. After their enzymatic degradation in the upper gastro-intestinal tract, the undigested fraction of these proteins is available for ... [more ▼]

Animal and plant proteins are major proteins sources in the human diet. After their enzymatic degradation in the upper gastro-intestinal tract, the undigested fraction of these proteins is available for fermentation by the microbiota of the large intestine leading to the production of short-chain fatty acids (SCFA), branched-chain fatty acids (BCFA), ammonia, biogenic amines, sulphur metabolites, phenols and indoles. As some of these compounds have genotoxic and cytotoxic effects, protein fermentation is considered as detrimental to the host’s epithelial health. BCFA are usually used as a marker of intestinal protein fermentation. We studied in vivo the impact of proteins from animal and plant origin, raw or after a cooking procedure, on the composition of gut microbiota and on fermentation end-products. Weanling rats were used as models of the human gut microbiota. Eight experimental diets were formulated with beef meat (Longissimus dorsi), chicken meat (Pectoralis major), white pea beans (Phaseolus vulgaris), soybeans (Glycine max), used raw and cooked, as sole source of protein in the diet. One casein diet was used as control. All diets, formulated to contain 15% of raw protein, were given to seven rats for four weeks. After euthanasia, caecal contents were collected. Pyrosequencing analyses (Roche 454 GS Junior Genome Sequencer) were performed to study the microbial composition. SCFA and BCFA were measured using HPLC (Waters 2690). Microbial composition in the caecum is associated to the type of dietary protein and to the cooking procedure applied. The proportion of BCFA in the caecal content is mainly affected by the type of protein. So BCFA represent respectively 04-06% and 35-44% of total SCFA with diets based on plant and on animal proteins. In conclusion, both the type of protein and the cooking procedure could impact the gut microbiota in terms of composition and of fermentative capacity. [less ▲]

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See detailGuidance Document on the Estimation of LOD and LOQ for Measurements in the Field of Contaminants in Food and Feed
Wenzl, Thomas; Haedrich, Johannes; Schaechtele, Alexander et al

Report (2016)

The European Union Reference Laboratory (EURL) for Polycyclic Aromatic Hydrocarbons (EURL PAH), the EURL for Heavy Metals in Feed and Food (EURL HM), the EURL for Mycotoxins (EURL Mycotoxins), and EURL ... [more ▼]

The European Union Reference Laboratory (EURL) for Polycyclic Aromatic Hydrocarbons (EURL PAH), the EURL for Heavy Metals in Feed and Food (EURL HM), the EURL for Mycotoxins (EURL Mycotoxins), and EURL for Dioxins and PCBs in Feed and Food aim to provide with this document guidance to official food control in the EU on the estimation of the limit of quantification of analytical methods for the determination of individual substances in the field of contaminants in feed and food. The document focusses on estimation of the limit of detection (LOD) and/or limit of quantification (LOQ) of polycyclic aromatic hydrocarbons (PAHs), heavy metals (HM), mycotoxins, and polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs). The concept presented here consists of two major routes: The first route responds to the requirements for determination of PAHs, HMs and Mycotoxins. The second route corresponds to PCDD/F and PCB analysis, where results are calculated as sumparameters and expressed in toxic equivalents (TEQs), converting thereby congener concentrations together with estimated LOQs using toxic equivalency factor (TEFs) into TEQs. Due to the nature of this more complex procedure, emphasis is put in the area of PCDD/F and PCB analysis on the LOQs, while LODs are of minor consequence. Terminology in this guidance document was adapted to the chemical analysis of contaminants in feed and food; hence, some of the general terms defined and used in international standards were replaced by more specific terms applicable to analytical chemistry. The presented statistical-mathematical approach is based on elements taken mainly from DIN 32645:2008-11 (DIN 2008) and ISO 11843-2:2000 (ISO 2000). This document covers only quantitative methods of analysis. The authors believe that LOD and LOQ values derived from the application of the presented experimental methodologies converge to a certain degree. Estimation of LOD/LOQ values based on blank measurements, and from calibration data is described. Signal-to-noise ratios are applied in the area of PCDD/Fs and PCBs. Mathematical terms and statistical background are presented as well. This guide document shall be applied systematically if measurement results are used for monitoring purposes and exposure modelling. However, authors are aware that precise knowledge of LOD/LOQ may not be required when assessing compliance with maximum levels exceeding LOD/LOQ. This guidance document shall be applied if maximum levels and analysis results are close to the expected LOQ. The authors acknowledge that the presented approach has its limitations and may not be generally applicable to all cases. [less ▲]

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See detailIntegrated microfluidic device for gold nanoparticles synthesis
Emonds-Alt, Gauthier ULg; Malherbe, Cédric ULg; Monbaliu, Jean-Christophe ULg et al

Poster (2016, May 31)

In order to perform the analysis of organic pollutant in trace by Raman spectroscopy, it is necessary to develop SERS substrates, such as noble metal nanoparticles (NPs). The synthesis of gold or silver ... [more ▼]

In order to perform the analysis of organic pollutant in trace by Raman spectroscopy, it is necessary to develop SERS substrates, such as noble metal nanoparticles (NPs). The synthesis of gold or silver NPs is used for analytical applications. It is therefore important to precisely control the synthesis of these SERS substrates to achieve reproducible measurements. Microfluidics is a very attractive technology for the control of the synthesis parameters such as temperature, reaction time and mixing conditions which affect both the size and the morphology of NPs. The synthesis of gold or silver NPs in microreactor is a technique we are already developing in the laboratory. We develop a method for the continuous synthesis of gold and silver NPs in a segmented regime capillary microreactor. The residence time and temperature have a significant effect on the size of the NPs, enabling to prepare different sizes of NPs using the same microreactor and the same precursor solutions. [less ▲]

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See detailMicroplastics contamination in three planktivorous and commercial fish species
Collard, France ULg; Das, Krishna ULg; Gilbert, Bernard ULg et al

Poster (2016, May)

In 2014, 311 million tonnes of plastics were produced worldwide while it is estimated that 10% ended up in the oceans. Plastics adsorb many pollutants, cause entanglements in many vertebrates and provoke ... [more ▼]

In 2014, 311 million tonnes of plastics were produced worldwide while it is estimated that 10% ended up in the oceans. Plastics adsorb many pollutants, cause entanglements in many vertebrates and provoke blockage of the digestive tract of marine mammals, birds and turtles. Plastics also fragment in smaller parts, forming microplastics (<5 mm). These microplastics have the same size than planktonic organisms and can thus be ingested by filter-feeders and planktivorous organisms including fish. Although planktivorous Clupeiforme species are the most fished species in the world (17 million tonnes in 2013), the possible impact of microplastic ingestion on this group has received little attention. The aim of this study was to quantify and to characterize the ingested anthropogenic particles (AP) in herrings (Clupea harengus), sardines (Sardina pilchardus) and anchovies (Engraulis encrasicolus). Twenty individuals of each species were sampled. Herrings and sardines were caught in the Channel and in the North Sea in January 2013 and in January 2014. Anchovies were sampled in July 2013. The stomach contents were digested by sodium hypochlorite to isolate AP and then they were analysed by Raman spectroscopy and measured. AP were constituted of microplastics (MP) and cellulose fibres, sometimes associated with dyes. We found several plastic families: polyethylene (PE), polypropylene (PP), polystyrene, polyacrylonitrile, polyethylene terephthalate, polyamide and poly(butyl methacrylate). MP occurred in 35%, 50% and 40% of stomach contents of anchovies, sardines and herrings, respectively. Anchovies ingested bigger AP (2 mm) than the two other species. MP was in majority PE followed by PP. Our study shows that highly commercial species are exposed to MP. Further research is needed as MP are transport medium for organic pollutants and their fate once in the organism is unknown. [less ▲]

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See detailMercury and persistent organic pollutant concentrations in free-ranging bottlenose dolphins from Lower Keys and Coastal Everglades (South Florida)
Damseaux, France ULg; Kiszka, Jeremy; Heithaus, Michael et al

Poster (2016, February 12)

The bottlenose dolphin (Tursiops truncatus) is a major apex predator and the most common cetacean species found in nearshore waters of South Florida, including the Lower Florida Keys (LFK) and the Florida ... [more ▼]

The bottlenose dolphin (Tursiops truncatus) is a major apex predator and the most common cetacean species found in nearshore waters of South Florida, including the Lower Florida Keys (LFK) and the Florida Coastal Everglades (FCE). The objective of this study was 1) to assess contamination levels of total mercury (T-Hg) in skin and persistent organic pollutants (PCBs, PBDEs, DDT, HCH, HCB, DLCs and PCDD/Fs) in blubber samples of bottlenose dolphins from the LFK (8 males and 16 females) and from the FCE (13 males and 9 females). Pollutants were analysed by the mean of Direct Mercury analyser (for T-Hg), GC-ECD (POPs) and GC-MS (DLCs and PCDD/Fs). The PCBs were the main compounds found in bottlenose dolphins from the LFK and FCE. The most present congeners where the CB no. 28, 52, 101, 138, 153 and 180 (ΣPCBs LFK males: 13420.5 ng.g-1 lipids, ΣPCBs LFK females: 9683.4 ng.g-1 lipids, ΣPCBs FCE males: 5637.9 ng.g-1 lipids, ΣPCBs FCE females: 1426.9 ng.g-1 lipids). PCBs concentrations were significantly higher in individuals from the LFK than those from the FCE but significantly lower than those from other locations in the south-eastern US. Unlike organic pollutants, T-Hg concentrations were significantly higher in FCE male dolphins (LFK: 2936.0 ng.g-1 dw, FCE: 10048.3 ng.g-1 dw). These high concentrations were the highest recorded in the south-eastern US and are most likely due to the presence of mangrove ecosystems. This study highlights the complexity of contaminant dynamics (inorganic vs. organic), even at small spatial scales. [less ▲]

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See detailThe performance of atmospheric pressure gas chromatography–tandem mass spectrometry compared to gas chromatography–high resolution mass spectrometry for the analysis of polychlorinated dioxins and PCBs in food and feed samples
ten Dam, Guillaume; Pussente, Igor; Scholl, Georges ULg et al

in Journal of Chromatography. A (2016)

Recently, gas chromatography tandem mass spectrometry (GC–MS/MS) has been added in EuropeanUnion (EU) legislation as an alternative to magnetic sector high resolution mass spectrometry (HRMS) for the ... [more ▼]

Recently, gas chromatography tandem mass spectrometry (GC–MS/MS) has been added in EuropeanUnion (EU) legislation as an alternative to magnetic sector high resolution mass spectrometry (HRMS) for the analysis of dioxins and dioxin like polychlorinated biphenyls (dl-PCB) in food and feed. In this study the performance of APGC–MS/MS compared to GC–HRMS is investigated and compared with EU legislation. The study includes the legislative parameters, relative intermediate precision standard devia-tion (SRw,rel), trueness, sensitivity, linear range and ion ratio tolerance. In addition, over 200 real samplesof large variety and spanning several orders of magnitude in concentration were analyzed by both techniques and the selectivity was evaluated by comparing chromatograms. The SRw,rel and trueness were evaluated using (in-house) reference samples and fulfill to EU legislation, though the SRw,rel was better with GC–HRMS. The sensitivity was considerably better than of GC–HRMS while the linear range was similar. Ion ratios were mostly within the tolerable range of ±15%. A (temporary unresolved) systematic deviation in ion ratio was observed for several congeners, yet this did not lead to exceeding of the maxi-mum ion ratio limits. The APGC–MS/MS results for the non-dioxin-like-PCBs (ndl-PCBs) were negatively biased, particularly for PCB138 and 153 in contaminated samples. The selectivity of APGC–MS/MS was lower for several matrices. Particularly for contaminated samples, interfering peaks were observed in the APGC chromatograms of the native compounds (dioxins) and labeled internal standards (PCBs). These can lead to biased results and ultimately to false positive samples. It was concluded that the determination of dioxins and PCBs using APGC–MS/MS meets the requirements set by the European Commission. However, due to generally better selectivity and SRw,rel, GC–HRMS is the preferred method for monitoring purposes. [less ▲]

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See detailOn the Habitability of Desert Varnish: a Combined Study by Micro-Raman Spectroscopy, X-Ray Diffraction and Methylated Pyrolysis-Gas Chromatography-Mass Spectrometry
Malherbe, Cédric ULg; Hutchinson, Ian; Ingley, Richard et al

in Astrobiology (2016)

In 2020, the ESA ExoMars and NASA Mars 2020 missions will be launched to Mars, searching for evidence of past and present life. In preparation for these missions, terrestrial analogue samples of rock ... [more ▼]

In 2020, the ESA ExoMars and NASA Mars 2020 missions will be launched to Mars, searching for evidence of past and present life. In preparation for these missions, terrestrial analogue samples of rock formations on Mars are studied in detail in order to optimize the scientific information that the analytical instrumentation will return. Desert varnishes are thin mineral coatings found on rocks in arid and semi-arid environments on Earth that are recognized as analogue samples. During the formation of desert varnishes (which takes many hundreds of years) organic matter is incorporated and microorganisms may also play an active role in the formation process. During this study, four complementary analytical techniques proposed for Mars missions (X-rays diffraction, Raman spectroscopy, elemental analysis and pyrolysis-gas chromatography-mass spectrometry) were used to interrogate samples of desert varnish and to describe their capacity to sustain life under extreme scenario. For the first time, both the geochemistry and the organic compounds associated with desert varnish are described using an identical set of samples. XRD and Raman spectroscopy measurements were used to non-destructively interrogate the mineralogy of the samples. In addition, the use of Raman spectroscopy instruments enabled the detection of β-carotene, a highly Raman active biomarker. The content and the nature of the organic material in the samples was further investigated using elemental analysis and methylated Py-GC-MS and a bacterial origin was determined to be likely. In the context of planetary exploration, we describe the habitable nature of desert varnish based on the bio-geochemical composition of the samples. Possible interference of the geological substrate on the detectability of pyrolysis products is also suggested. [less ▲]

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See detailToxicokinetics of selenium in the slider turtle Trachemys scripta
Dyc, Christelle; Far, Johann ULg; Gandar, Frederic ULg et al

in Ecotoxicology (2016), 25

Selenium (Se) is an essential element that can be harmful for wildlife. However, its toxicity in poikilothermic amniotes, including turtles, remains poorly investigated. The present study aims at ... [more ▼]

Selenium (Se) is an essential element that can be harmful for wildlife. However, its toxicity in poikilothermic amniotes, including turtles, remains poorly investigated. The present study aims at identifying selenium toxicokinetics and toxicity in juvenile slider turtles (age: 7 months), Trachemys scripta, dietary exposed to selenium, as selenomethionine SeMet, for eight weeks. Non-destructive tissues (i.e. carapace, scutes, skin and blood) were further tested for their suitability to predict selenium levels in target tissues (i.e. kidney, liver and muscle) From conservation perspective. 130 juvenile yellow-bellied slider turtles were assigned in three groups of 42 individuals each (i.e. control, SeMet1 and SeMet2). These groups were subjected to a feeding trial including an eight-week supplementation period SP8 and a following four-week elimination period EP4. During the SP8, turtles fed on diet containing 1.1 ± 0.04, 22.1 ± 1.0 and 45.0 ± 2.0 µg.g-1 of selenium (control, SeMet1 and SeMet2, respectively). During the EP4, turtles fed on non-supplemented diet. At different time during the trial, six individuals per group were sacrificed and tissues collected (i.e. carapace, scutes, skin, blood, liver, kidney, muscle) for analyses. During the SP8 (Figure 1), both SeMet1 and SeMet2 turtles efficiently accumulated selenium from a SeMet dietary source. The more selenium was concentrated in the food, the more it was in the turtle body but the less it was removed from their tissues. Moreover, SeMet was found to be the more abundant selenium species in turtles’ tissues. Body condition (i.e. growth in mass and size, feeding behaviour and activity) and survival of the SeMet1 and SeMet2 turtles seemed to be unaffected by the selenium exposure. There were clear evidences that reptilian species are differently affected by and sensitive to selenium exposure but the lack of any adverse effects was quite unexpected. [less ▲]

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See detailCompensatory Metabolism Promotes Cancer Cell Adaptation to HDAC5 Silencing
Hendrick, Elodie ULg; Peixoto, Paul; Polese, Catherine et al

Poster (2015, December 03)

Detailed reference viewed: 46 (14 ULg)