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See detailSequence-based association analysis identifies coding and non-coding variants in HFM1, MLH3, MSH4, MSH5, RNF212 and RNF212B with large effects on male and female recombination rate in cattle
Kadri, Naveen Kumar ULg; Harland, Chad ULg; Faux, Pierre ULg et al

Poster (2016, June 15)

We herein study genetic recombination in three dairy cattle populations from France, New-Zealand and the Netherlands. We identify 2,395,177 crossover (CO) events in sperm cells transmitted by 2,940 sires ... [more ▼]

We herein study genetic recombination in three dairy cattle populations from France, New-Zealand and the Netherlands. We identify 2,395,177 crossover (CO) events in sperm cells transmitted by 2,940 sires to 94,516 offspring, and 579,996 CO events in oocytes transmitted by 11,461 cows to 25,332 offspring. When measured in identical family structures, the average number of CO in males (23.3) was found to be larger than in females (21.4). The heritability of global recombination rate (GRR) was estimated at 0.13 in males and 0.08 in females. The genetic correlation was equal to 0.66, indicating that shared variants are influencing GRR in both genders. Haplotype-based genome-wide association studies revealed seven genome-wide significant QTL. Variants identified by next-generating sequencing in 5 Mb windows encompassing the QTL peaks were imputed in order to perform a sequence-based association analysis. For four QTLs, we identified missense mutations in genes known to be involved in meiotic recombination among the most significantly associated variants. Most of the identified mutations had significant effects in both genders with three of them accounting each for approximately 10% of the genetic variance in males (the allelic substitution effect being approximately equal to one additional CO per genome). Thus, a large fraction of the genetic variance is associated with missense mutations in genes known to be involved in meiotic recombination. Our results are very different from reports of recombination in other species. For instance, in human, recombination rate is higher in females, distinct variants affect recombination rate in males and females, and the genetic correlation is close to 0, whereas in cattle, we observed a higher recombination rate in males controlled by shared variants effective in both sexes. [less ▲]

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See detailMitochondrial function and aerobic capacity assessed by high resolution respirometry in Thoroughbred horses
Serteyn, Didier ULg; Ceusters, Justine ULg; Nonnenmacher et al

in Comparative Exercise Physiology (2016), 12(2), 67-73

During the initial stages of training of young Thoroughbred horses, low intensity exercise is employed to increase aerobic capacity. High Resolution Respirometry (HRR) allows the determination of aerobic ... [more ▼]

During the initial stages of training of young Thoroughbred horses, low intensity exercise is employed to increase aerobic capacity. High Resolution Respirometry (HRR) allows the determination of aerobic capacities in small samples of permeabilised muscle fibres. The aim of the study was to measure the mitochondrial function by HRR in Thoroughbred horses, to compare these values to Warmblood horses and to evaluate the effect of a 10-weeks training period. The mitochondrial function was measured by HRR using different substrate-uncoupler protocols (SUIT 1 and 2) in muscle microbiopsies from two groups of untrained horses: 17 Warmblood and 8 Thoroughbred and in the group of 8 Thoroughbred horses before and after a 10-week training period. The SUIT1 protocol employed to compare the two groups of horses showed that in Thoroughbred horses, the mean values for oxygen flux expressed as tissue mass-specific respiration were significantly higher for complex I (CI)Glutamate+Malate, CI + complex II, and maximum electron transport capacities (ETSmax) than the mean values measured in Warmblood horses. The SUIT 1 and SUIT 2 protocols revealed large differences among Thoroughbred horses before and after training. The SUIT 2 protocols showed a significant difference for the complex I activity before and after training but only when the oxygen flux was expressed as percentage of ETSmax. This study shows the interest of HRR in equine sport medicine and exercise physiology, but shows that the technique requires further refinement. Indeed significant differences have been shown between the Thoroughbred and the Warmblood horses highlighting the need to have baseline data for each breed. The Thoroughbred horses had globally a high oxidative phosphorylation capacity with an increase of CI activity induced by an aerobic training program. [less ▲]

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See detailAn efficient and flexible software tool for genome-wide association interaction studies
Van Lishout, François ULg

Doctoral thesis (2016)

Humans are made up of approximately 3.2 billion base pairs, out of which about 62 million can vary from one individual to another. These particular base pairs are called single nucleotide polymorphisms ... [more ▼]

Humans are made up of approximately 3.2 billion base pairs, out of which about 62 million can vary from one individual to another. These particular base pairs are called single nucleotide polymorphisms (SNPs). It is well known that some particular combination of SNP values increase dramatically the risk of contracting certain type of disease, like Crohn's disease, Alzheimer, diabetes and cancer, just to name a few. However, there are still a lot of new discoveries to make and specialized software is required for this task. It has been shown that individual SNPs cannot account for much of the heritability on their own. Therefore, this PhD thesis is dedicated to interaction studies, the purpose of which is to identify pairs of SNPs and/or environmental factors that might regulate the susceptibility to the disease under investigation. Model-Based Multifactor Dimensionality Reduction (MB-MDR) is a powerful and flexible methodology to perform interaction analysis, while minimizing the amount of false discoveries. Before this thesis, the only available implementation was an R-package taking days to analyze a dataset composed of just hundred of SNPs. However, a typical dataset contains hundreds of thousands or millions of SNPs, even after data cleaning and quality control. The aim of this thesis is to write a software able to analyze such datasets within a few days with the MB-MDR methodology. In other words, the goal is to get 10^8 times faster than the R-package, while still remaining powerful, flexible and keeping the amount of false discoveries low. Several contributions were needed to reach this goal and are presented in this thesis. First, a new software was written from scratch in C++, in order to be able to optimize every single computation, instead of relying on too generic functions as was the case for the R-package. Second, the methodology itself was improved, irrespective of the programming language. Indeed, MB-MDR is based on the maxT algorithm (introduced by Westfall&Young in 1993) to assess significance of the results and it can be customized for interaction analysis. A first major contribution of this PhD work, called Van Lishout's implementation of maxT, was introduced in 2011. The parallel version of this algorithm enables to analyze a dataset composed of hundred thousands of SNPs within a few days. The most important contribution of this thesis, called the gammaMAXT algorithm, was introduced in 2014. The parallel version enables to analyze a dataset composed of one million SNPs within one day. In this thesis, we also propose a new viewpoint to handle population stratification and correct for covariates. Many simulated and real-life data analysis are provided, to highlight the flexibility of the software and its ability to find interesting results from a biological point of view. The latest version, called mbmdr-4.4.1.out, can be downloaded freely at http://www.statgen.ulg.ac.be with the corresponding documentation. [less ▲]

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See detailRhodococcus erythropolis T902.1 as a bioaugmentation starter: mechanisms, constrains and potentialities for the hydrocarbon degradation
Masy, Thibaut ULg

Doctoral thesis (2016)

Since the advent of the industrial revolution in the 19th century, anthropogenic activities and lack of environmental concern gave birth to numerous contaminated areas. Amongst released pollutants ... [more ▼]

Since the advent of the industrial revolution in the 19th century, anthropogenic activities and lack of environmental concern gave birth to numerous contaminated areas. Amongst released pollutants, hydrocarbons (HC) are the most widespread in the environment but they can also constitute a carbon source for numerous microorganisms. Therefore, bioremediation (i.e. the use of microorganisms to degrade pollutants) appears as an ecologically- and cost-effective technique compared to chemical or physical treatments. This biotreatment technology often relies either on stimulating indigenous microorganisms already present in soil (biostimulation) or on adding specific microbial degraders (bioaugmentation) to enhance the natural attenuation of contaminants. However, there is a need for improved understanding of the causes that can lead to its failure or its low efficiency, such as diverse environmental constraints or poor adaptation ability of laboratory-cultivated microorganisms. Amongst bacteria studied, Rhodococcus sp. has been previously described as a potential candidate for bioaugmentation due to its ability to degrade a broad range of organic pollutants, to produce biosurfactants, which improves pollutant bioavailability, and to rapidly adapt to many environmental stresses (e.g. desiccation, low temperature, high salinity). The main objective of this work is thus to assess the potentiality and limitations in the use of a specific strain, Rhodococcus erythropolis T902.1, to degrade HC (from simple n-alkanes to polyaromatic) in diverse field conditions. The factors limiting such a process have to be identified and, as much as possible, overcome. A first bioaugmentation experiment in microcosms aimed at identifying these constrains in carbon and clay-rich soils contaminated with heating oil. This treatment was successful in strongly polluted soil, since the addition of the strain T902.1 helped in redirecting the limited quantity of available oxygen towards a higher HC degradation and also correlated with a higher proportion of degrading genes in bioaugmented soils, compared to biostimulated and control ones. However, this effect decreased with time as T902.1 development was curtailed by competition and potentially predation from the endogenous flora. In addition, HC were heterogeneously distributed and this hampered the detection of a real degradation in lowest polluted soils. As a result, inoculation should be targeted to highly polluted areas (e.g. contaminant source zones), but it requires controlling soil heterogeneity.   We thus resorted to electrical resistivity tomography (ERT), to describe this heterogeneity and to monitor bacterial HC degradation activity. This geophysical tool could discriminate lithological heterogeneities that were artificially introduced in a 2 m³ pilot. Compared to a first insufficient biostimulation phase, the introduction of R. erythropolis T902.1 in this pilot led to a HC depletion of almost 80% (6900 to 1600 ppm) in 3 months in the injection zone, where pollutants were less bioavailable. Simultaneously, HC mineralization and biosurfactant production were deduced from the monitoring of ERT, biological and physicochemical parameters. In another study, R. erythropolis T902.1 could form stable biofilms on the materials constituting draining pavement structures, which allowed its long-term survival in a real parking lot and improved the decontamination of runoff water drained through this structure during pollution tests carried out at a pilot scale. This indicates that the strain could be widely used in other decontaminating systems and not only in soil. Furthermore, this biofilm formation could be triggered by an appropriate pre-adaptation of the cells before their injection in the polluted environment, to ensure a higher ecological robustness of the inoculum, compared to the one observed in the microcosm experiment. A third constrain is the poor or slow degrading activity toward some recalcitrant compounds, such as polyaromatic HC (PAH). Metallic nanoparticles synthesized by a sol-gel process were considered as potential catalysts for the improvement of degradation kinetics. Iron nanoparticles boosted the bacterial catalytic activity of the strain T902.1 in liquid cultures containing biphenyl as the sole carbon source. Following results suggested that the iron encapsulated in the porous silica matrix, was progressively attracted by siderophores (heterobactins) produced by the strain. However, this hypothesis has still to be confirmed by further analyses. From these experiments, R. erythropolis T902.1 globally proved to compete and improve degradation rates in highly polluted soils compared to biostimulation, even under low oxygen and nutrient contents. Notably, the production of trehalolipidic biosurfactants enhances HC bioavailability for their further uptake by the strain and surrounding microorganisms. Furthermore, this strain forms stable biofilms on several supports, which increases its lifespan and paves the way for many applications in bioremediation systems. Finally, it can also be used in synergy with sol-gel iron nanoparticles to treat recalcitrant compounds such as PAH and some chlorinated aromatics, but this combination needs to be further tested in more complex media, such as soil or waste water. [less ▲]

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See detailLa question urbaine revisitée. Analyse socio-politique comparée de la régulation publique des inégalités environnementales
Lejeune, Zoé ULg

Doctoral thesis (2016)

Les inégalités environnementales forment un relatif « impensé » de la plupart des politiques publiques qui sont aujourd’hui mises en place dans nos villes. S’il apparaît qu’il y a une sous-estimation de ... [more ▼]

Les inégalités environnementales forment un relatif « impensé » de la plupart des politiques publiques qui sont aujourd’hui mises en place dans nos villes. S’il apparaît qu’il y a une sous-estimation de cet enjeu de la part des autorités politiques au sens large, il nous a semblé utile de mieux comprendre les processus socio-politiques à l’œuvre. C’est un double mouvement que nous interrogeons dans la thèse. D’une part, quels sont les processus « sociétaux », collectifs qui contribuent à la production de phénomènes inégalitaires en matière environnementale ? D’autre part, quels sont les dispositifs socio-politiques qui se dessinent afin d’y trouver une solution collective et politique ? La première approche privilégiée pose la question des conditions sociétales de la formation et de l’émergence des inégalités environnementales : distribution des charges environnementales, inégale participation dans la vie publique et collective et inégalités socio-spatiales. Cette première question nous a conduit à mobiliser les données du Baromètre social de la Wallonie 2012 et son module de questions sur l’environnement. La seconde grande question interroge les modalités de la gestion collective et publique des inégalités environnementales, à savoir les solutions mises en place aujourd’hui pour y faire face. Cette analyse se propose dès lors d’étudier les modalités de la régulation publique des inégalités environnementales dans une perspective comparative internationale face à la transformation de l’action collective et publique urbaine. Pour ce faire, nous avons réalisé des enquêtes de terrain qualitatives (entretiens semi-dirigés) dans plusieurs villes, en Angleterre (Sheffield) et en Belgique (Liège). Celles-ci nous ont conduit à proposer un modèle conceptuel de lecture de la régulation publique des inégalités environnementales en milieu urbain. [less ▲]

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See detailPsychocriminologie des troubles sévères du comportement chez les adolescents
Garcet, Serge ULg

Conference given outside the academic context (2016)

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See detailétape de résidence du projet état d'urgence
Da Silva, Amanda Carolina ULg

Conference given outside the academic context (2016)

Amanda Da Silva, chercheuse en migrations internationales, analyse les politiques migratoires de l’Union Européenne, à travers la notion de « sécurisation de l’immigration ». Ce courant théorique ... [more ▼]

Amanda Da Silva, chercheuse en migrations internationales, analyse les politiques migratoires de l’Union Européenne, à travers la notion de « sécurisation de l’immigration ». Ce courant théorique vient de l’école d’études critiques de la sécurité et a pour concepts centraux : menace, sécurité et frontières. Par la notion de sécurisation, l’immigration est conceptualisée par la communauté politique comme une source d’insécurité. Des frontières sont érigées pour protéger une société où les discours et les politiques migratoires restrictives cristallisent l’image de l’immigrant en tant que menace. Cette recherche révèle que l’absence d’accueil de la part des États et le manque d’information généralisé servent la construction de camps où les réfugiés sont à la merci du marché de l’immigration clandestine et de la violence. [less ▲]

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See detailLe rôle du Système européen des comptes nationaux et régionaux (SEC) dans la gouvernance budgétaire européenne
Piron, Damien ULg

Conference given outside the academic context (2016)

Detailed reference viewed: 17 (1 ULg)
See detail"A Humument" de Tom Phillips dans le contexte des néo-avant-gardes européennes
Belloi, Livio ULg

Scientific conference (2016, June 13)

Cette conférence s'attache à replacer "A Humument" de Tom Phillips dans le contexte des néo-avant-gardes européennes. L'accent est porté sur la matérialité propre au texte de Phillips, mais aussi sur de ... [more ▼]

Cette conférence s'attache à replacer "A Humument" de Tom Phillips dans le contexte des néo-avant-gardes européennes. L'accent est porté sur la matérialité propre au texte de Phillips, mais aussi sur de possibles connexions avec la bande dessinée contemporaine et le cinéma expérimental. [less ▲]

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See detailReversal of global atmospheric ethane and propane trends largely due to US oil and natural gas production
Helmig, Detlev; Rossabi, Samuel; Hueber, Jacques et al

in Nature Geoscience (2016)

Non-methane hydrocarbons such as ethane are important precursors to tropospheric ozone and aerosols. Using data from a global surface network and atmospheric column observations we show that the steady ... [more ▼]

Non-methane hydrocarbons such as ethane are important precursors to tropospheric ozone and aerosols. Using data from a global surface network and atmospheric column observations we show that the steady decline in ethane concentrations that began in the 1970s halted between 2005 and 2010 in most of the Northern Hemisphere, and has since reversed. We calculate a yearly increase in ethane emissions in the Northern Hemisphere of 0.42 (+/-0.19) Tg/yr between mid-2009 and mid-2014. The largest increases in ethane and for the shorter-lived propane are seen over the central and eastern USA, with a spatial distribution that suggests North American oil and natural gas development as the primary source of increasing emissions. By including other co-emitted oil and natural gas non-methane hydrocarbons, we estimate a Northern Hemisphere total non-methane hydrocarbon yearly emission increase of 1.2 (+/-0.8) Tg/yr. Atmospheric chemical transport modelling suggests that these emissions could augment summertime mean surface ozone by several nanomoles per mole near oil and natural gas production regions. Methane/ethane oil and natural gas emission ratios suggest a significant increase in associated methane emissions; however, this increase is inconsistent with observed leak rates in production regions and changes in methane’s global isotopic ratio. [less ▲]

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See detailThree Essays on Market Liquidity in Equity Markets
Bazgour, Tarik ULg

Doctoral thesis (2016)

Over the past decades, market liquidity has been a major issue for stock market participants and even becomes one of the most important challenges since the recent financial crisis. In this context, this ... [more ▼]

Over the past decades, market liquidity has been a major issue for stock market participants and even becomes one of the most important challenges since the recent financial crisis. In this context, this dissertation is centered on this topic and presents three empirical essays incorporating liquidity considerations in three different subfields of Finance, namely, asset pricing, portfolio allocation and mutual fund timing. The first essay (Chapter 2) is related to asset pricing and demonstrates that liquidity and quality are priced characteristics in the stock market, but their pricing is conditional on market volatility conditions. The second essay (Chapter 3) is devoted to portfolio allocation and shows that aggregate market liquidity shocks has a significant influence on optimal portfolio allocations. In addition, it emphasizes that liquidity-responsive strategies could be a valuable tool for investors and portfolio managers to actively manage risks and capture return opportunities. The third essay (Chapter 4) focuses rather on mutual fund timing and examines what style liquidity timing skills may mutual fund managers possess. This study highlights that, in anticipation of aggregate market liquidity changes, mutual funds do not switch their investments between stocks and cash but they rather switch between only small and large stocks. Overall, the main message to take away from this research is that investors and portfolio managers should take into consideration both the liquidity of their individual stocks and the liquidity of the market as a whole. [less ▲]

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See detailLa filière fonio en Afrique de l’ouest: analyse des potentialites
Andres, Ludovic ULg; Lebailly, Philippe ULg

Conference given outside the academic context (2016)

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See detailAnomalous diffusion and non-monotonic relaxation processes in Ge-Se liquids
Yildirim, Can ULg; Raty, Jean-Yves ULg; Micoulaut, Matthieu

in Journal of Chemical Physics (2016), 144

We investigate the dynamical properties of liquid GexSe100−x as a function of Ge content by first-principles molecular dynamic simulations for a certain number of temperatures in the liquid state. The ... [more ▼]

We investigate the dynamical properties of liquid GexSe100−x as a function of Ge content by first-principles molecular dynamic simulations for a certain number of temperatures in the liquid state. The focus is set on ten compositions (where x ≤ 33%) encompassing the reported flexible to rigid and rigid to stressed-rigid transitions. We examine diffusion coefficients, diffusion activation energies, glassy relaxation behavior, and viscosity of these liquids from Van Hove correlation and intermediate scattering functions. At fixed temperature, all properties/functions exhibit an anomalous behavior with Ge content in the region 18%-22%, and provide a direct and quantitative link to the network rigidity. [less ▲]

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See detailLignin as a bio-based flame retardant additive: Pretreatments overview
Istasse, Thibaut ULg; Jacquet, Nicolas ULg; Richel, Aurore ULg

Poster (2016, June 12)

Lignin is a cross-linked phenol polymers from plant cells wall and is the third most abundant organic material after cellulose and hemicelluloses. This substance was studied as a flame retardant for ... [more ▼]

Lignin is a cross-linked phenol polymers from plant cells wall and is the third most abundant organic material after cellulose and hemicelluloses. This substance was studied as a flame retardant for various polymers and represents an interesting opportunity to create more eco-friendly and safer plastics and resins. This poster explains one potential technology to extract lignin: the organosolv treatment. [less ▲]

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See detailTeneurs en fibres de légumes cultivés en Wallonie
Bindelle, Jérôme ULg

Conference given outside the academic context (2016)

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See detailL'histoire de la bande dessinée par ses auteurs : une historiographie ‘Bizarro’
Crucifix, Benoît ULg

Conference given outside the academic context (2016)

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See detailWater familiarization testing battery adapted for young children
Vandermeulen, Mary ULg; Schietecatte, Delphine; Delvaux, Anne ULg et al

Poster (2016, June 11)

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See detailApprendre à programmer : quels intérêts ? quelles limites ?
Barnabé, Fanny ULg

Conference given outside the academic context (2016)

Table ronde en compagnie de Jonathan Berger sur les intérêts, les possibles mais aussi les limites de la programmation.

Detailed reference viewed: 26 (1 ULg)
See detailTenure choice and the tax treatment of mortgage loans in Belgium
Xhignesse, Guillaume ULg

Conference (2016, June 11)

Detailed reference viewed: 26 (6 ULg)