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See detailNew disruption cassettes for rapid gene disruption and marker rescue in the yeast Yarrowia lipolytica
Fickers, Patrick ULg; Le Dall, M. T.; Gaillardin, C. et al

in Journal of Microbiological Methods (2003), 55(3), 727-737

Yarrowia lipolytica is one of the most extensively studied nonconventional yeasts. Unfortunately, few methods for gene disruption have been reported for this yeast, and all of them are time-consuming and ... [more ▼]

Yarrowia lipolytica is one of the most extensively studied nonconventional yeasts. Unfortunately, few methods for gene disruption have been reported for this yeast, and all of them are time-consuming and laborious. The functional analysis of unknown genes requires powerful disruption methods. Here, we describe such a new method for rapid gene disruption in Y lipolytica. This knockout system combines SEP method and the Cre-lox recombination system, facilitating efficient marker rescue. Versatility was increased by using both auxotrophic markers like ylURA3 and ylLEU2, as well as the antibiotic resistance marker hph. The hph marker, which confers resistance to hygromycin-B, allows gene disruption in a strain lacking any conventional auxothrophic marker. The disruption cassette was shown to integrate at the correct locus at an average frequency of 45%. Upon expression of Cre recombinase, the marker was excised at a frequency of 98%, by recombination between the two lox sites. This new method for gene disruption is an ideal tool for the functional analysis of gene families, or for creating large-scale mutant collections in general. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

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See detailIn vivo dynamic ME-MRI reveals differential functional responses of RA- and area X-projecting neurons in the HVC of canaries exposed to conspecific song
Tindemans, I.; Verhoye, M.; Balthazart, Jacques ULg et al

in European Journal of Neuroscience (2003), 18(12), 3352-3360

HVC (nidopallial area, formerly known as hyperstriatum ventrale pars caudalis), a key centre for song control in oscines, responds in a selective manner to conspecific songs as indicated by ... [more ▼]

HVC (nidopallial area, formerly known as hyperstriatum ventrale pars caudalis), a key centre for song control in oscines, responds in a selective manner to conspecific songs as indicated by electrophysiology. However, immediate-early gene induction cannot be detected in this nucleus following song stimulation. HVC contains neurons projecting either towards the nucleus robustus archistriatalis (RA; motor pathway) or area X (anterior forebrain pathway). Both RA- and area X-projecting cells show auditory responses. The present study analysed these responses separately in the two types of HVC projection neurons of canaries by a new in vivo approach using manganese as a calcium analogue which can be transported anterogradely and used as a paramagnetic contrast agent for magnetic resonance imaging (MRI). Manganese was stereotaxically injected into HVC and taken up by HVC neurons. The anterograde axonal transport of manganese from HVC to RA and area X was then followed by MRI during approximate to 8 h and changes in signal intensity in these targets were fitted to sigmoid functions. Data comparing birds exposed or not to conspecific songs revealed that song stimulation specifically affected the activity of the two types of HVC projection neurons (increase in the sigmoid slope in RA and in its maximum signal intensity in area X). Dynamic manganese-enhanced MRI thus allows assessment of the functional state of specific neuronal populations in the song system of living canaries in a manner reminiscent of functional MRI (but with higher resolution) or of 2-deoxyglucose autoradiography (but in living subjects). [less ▲]

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See detailInverse Estimates of Anthropogenic Carbon Dioxide From Ocean Interior Carbon Measurements and Ocean General Circulation Models
Mikaloff Fletcher, S. E.; Gruber, N. P.; Jacobson, A. R. et al

Conference (2003, December)

The ocean is an important sink for atmospheric carbon dioxide, and the exchange of carbon dioxide between the atmosphere and ocean plays a critical role in determining the spatial distribution of ... [more ▼]

The ocean is an important sink for atmospheric carbon dioxide, and the exchange of carbon dioxide between the atmosphere and ocean plays a critical role in determining the spatial distribution of atmospheric carbon dioxide. However, there is still a great deal of uncertainty in both magnitude and regional patterns of anthropogenic uptake associated with estimates of oceanic carbon fluxes. Using a recently developed technique, exchange of anthropogenic carbon dioxide across the air-sea interface have been estimated from observations of dissolved inorganic carbon and nutrient concentrations and an Ocean General Circulation Model (OGCM) using a Green's function inverse modeling technique. Previous sensitivity studies have shown that model circulation error is an important source of error in the ocean inversion. In order to address the role of ocean circulation biases, inverse estimates of anthropogenic carbon air-sea gas exchange are presented using basis functions from a suite of seven different OGCM's. The robustness of the ocean inversion will be quantified and the effects of differences between approaches to modeling ocean circulation on the ocean carbon cycle will be explored. These results will be discussed in the context of recent atmospheric inverse estimates. [less ▲]

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See detailOverproduction of lipase by Yarrowia lipolytica mutants
Fickers, Patrick ULg; Nicaud, J. M.; Destain, Jacqueline ULg et al

in Applied Microbiology & Biotechnology (2003), 63(2), 136-142

Non-genetically modified mutants with increased capacities of extracellular lipase production were obtained from Yarrowia lipolytica strain CBS6303 by chemical mutagenesis. Of the 400 mutants isolated ... [more ▼]

Non-genetically modified mutants with increased capacities of extracellular lipase production were obtained from Yarrowia lipolytica strain CBS6303 by chemical mutagenesis. Of the 400 mutants isolated, LgX64.81 had the highest potential for the development of an industrial lipase production process. This mutant exhibits lipase production uncoupled from catabolite repression by glucose, and a 10-fold increased productivity upon addition of oleic acid. Using a LIP2-LacZ reporter gene, we demonstrate that the mutant phenotype originates from a trans-acting mutation. The glucose uptake capacity of LgX64.81 is reduced 2.5-fold compared to the wild-type-strain, and it exhibits high lipase production on glucose medium. A trans-acting mutation in a gene involved in glucose transport could thus explain this mutant phenotype. [less ▲]

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See detailTribology of SiC/SiC Ceramic Matrix Composites in Liquid Oxygen in Relation to the Design of Hydrostatic Bearings
Bozet, Jean-Luc ULg; NELIS, M.; LEUCHS, Martin et al

in Tribotest Journal (2003), 10(2), 105-115

This paper aims with the characterization of ceramic matrix composites for bearing applications in LOX. First, compatibility tests have been performed to assume the safety and feasibility of further ... [more ▼]

This paper aims with the characterization of ceramic matrix composites for bearing applications in LOX. First, compatibility tests have been performed to assume the safety and feasibility of further research operations. Then tribology tests were made on a pin-on-disc apparatus using LOX as working environment. The measurement of friction and wear allowed a comparison between different kinds of CMC and steel 440C materials. As a logical approach, a real geometry test rig is now being built up. The design of a hybrid journal bearing has been finished and the manufacturing of the rig components started. [less ▲]

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See detailClinique phoniatrique
FINCK, Camille ULg

Scientific conference (2003, December)

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See detailRésistances bactériennes aux antibiotiques : le cas des pathogènes respiratoires du bovin
Mainil, Jacques ULg

Scientific conference (2003, December)

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See detailQuantitative analysis of strychnine and brucine in Strychnos nux-vomica using H-1-NMR
Frederich, Michel ULg; Choi, Y. H.; Verpoorte, R.

in Planta Medica (2003), 69(12), 1169-1171

A quantitative analysis using H-1-NMR (Q-NMR) has been developed for the determination of strychnine and brucine in Strychnos nux-vomica seeds and stems. The advantages of the method are that no reference ... [more ▼]

A quantitative analysis using H-1-NMR (Q-NMR) has been developed for the determination of strychnine and brucine in Strychnos nux-vomica seeds and stems. The advantages of the method are that no reference alkaloids are needed for calibration curves, the quantification could be directly realized on a crude extract, strychnine and brucine could easily be distinguished, an overall profile of the preparation (including non alkaloid compounds) could be directly obtained, and a very significant time-gain could be achieved, in comparison to conventional HPLC methods, for instance. [less ▲]

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See detailRight lobe living-related liver transplantation in a Jehovah's Witness
Detry, Olivier ULg; De Roover, Arnaud ULg; Kaba, Abdourahmane ULg et al

in Transplant International (2003), 16(12), 895-896

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See detailRise and survival of bovine herpesvirus 1 recombinants after primary infection and reactivation from latency
Schynts, F.; Meurens, F.; Detry, Bruno et al

in Journal of Virology (2003), 77(23), 12535-12542

Recombination is thought to be an important source of genetic variation in herpesviruses. Several studies, performed in vitro or in vivo, detected recombinant viruses after the coinoculation of two ... [more ▼]

Recombination is thought to be an important source of genetic variation in herpesviruses. Several studies, performed in vitro or in vivo, detected recombinant viruses after the coinoculation of two distinguishable strains of the same herpesvirus species. However, none of these studies investigated the evolution of the relative proportions of parental versus recombinant progeny populations after coinoculation of the natural host, both during the excretion and the reexcretion period. In the present study, we address this by studying the infection of cattle with bovine herpesvirus 1 (BoHV-1). The recombination of two BoHV-1 mutants lacking either glycoprotein C (gC(-)/gE(+)) or E (gC(+)/gE(-)) was investigated after inoculation of cattle by the natural route of infection. The results demonstrated that (i) recombination is a frequent event in vivo since recombinants (gC(+)/gE(+) and gC(-)/gE(-)) were detected in all coinoculated calves, (ii) relative proportions of progeny populations evolved during the excretion period toward a situation where two populations (gC(+)/gE(+) and gC(-)/gE(+)) predominated without fully outcompeting the presence of the two other detected populations (gC(+)/gE(-) and gC(-)/gE(-)), and (iii) after reactivation from latency, no gC(+)/gE(-) and gC(-)/gE(-) progeny viruses were detected, although gC(+)/gE(-) mutants, when inoculated alone, were detected after reactivation treatment. In view of these data, the importance of gE in the biology of BoHV-1 infection and the role of recombination in herpesvirus evolution are discussed. [less ▲]

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See detailPsychrophilic enzymes: Hot topics in cold adaptation
Feller, Georges ULg; Gerday, Charles ULg

in Nature Reviews Microbiology (2003), 1(3), 200-208

More than three-quarters of the Earth's surface is occupied by cold ecosystems, including the ocean depths, and polar and alpine regions. These permanently cold environments have been successfully ... [more ▼]

More than three-quarters of the Earth's surface is occupied by cold ecosystems, including the ocean depths, and polar and alpine regions. These permanently cold environments have been successfully colonized by a class of extremophilic microorganisms that are known as psychrophiles (which literally means cold-loving). The ability to thrive at temperatures that are close to, or below, the freezing point of water requires a vast array of adaptations to maintain the metabolic rates and sustained growth compatible with life in these severe environmental conditions. [less ▲]

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See detailIdentification of specific biomarkers related to the effects of pollutants on the immune system of marine mammals
Brenez, Cécile; Gerkens, Pascal; Jauniaux, Thierry ULg et al

Poster (2003, December)

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See detailStabilization of periodic orbits in a wedge billiard
Sepulchre, Rodolphe ULg; Gerard, Manuel

in Proceedings of the 42nd IEEE Conference on Decision and Control (2003, December)

This paper introduces a stabilization problem for an elementary impact control system in the plane. The rich dynamical properties of the wedge billiard, combined to the relevance of the associated ... [more ▼]

This paper introduces a stabilization problem for an elementary impact control system in the plane. The rich dynamical properties of the wedge billiard, combined to the relevance of the associated stabilization problem for feedback control issues in legged robotics make it a valuable benchmark for energy-based stabilization of impact control systems. [less ▲]

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See detailThe aromatase knockout (ArKO) mouse provides new evidence that estrogens are required for the development of the female brain
Bakker, Julie ULg; Honda, S.; Harada, N. et al

in Annals of the New York Academy of Sciences (2003), 1007

The classic view of sexual differentiation is that the male brain develops under the influence of testicular secretions, whereas the female brain develops in the absence of any hormonal stimulation ... [more ▼]

The classic view of sexual differentiation is that the male brain develops under the influence of testicular secretions, whereas the female brain develops in the absence of any hormonal stimulation. However, several studies have suggested a possible role of estradiol in female neural development, although they did not provide unequivocal evidence that estradiol is indispensable for the development of the female brain and behavior. As a result, the hypothesis subsequently languished because of the lack of a suitable animal model to test estrogen's possible contribution to female differentiation. The recent introduction of the aromatase knockout (ArKO) mouse, which is deficient in aromatase activity because of a targeted mutation in the CYP19 gene and therefore cannot aromatize androgen to estrogen, has provided a new opportunity to reopen the debate of whether estradiol contributes to the development of the female brain. Female ArKO mice showed reduced levels of lordosis behavior after adult treatment with estradiol and progesterone, suggesting that estradiol is required for the development of the neural mechanisms controlling this behavior in female mice. The neural systems affected may include the olfactory systems in that ArKO females also showed impairments in olfactory investigation of odors from conspecifics. Thus, the classic view of sexual differentiation, that is, the female brain develops in the absence of any hormonal secretion, needs to be re-examined. [less ▲]

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See detailTowards a consistant safety format of steel beam-columns: application of the new interaction formulae for ambient temperature to elevated temperatures
Vila Real, Paulo; Lopes, Nuno; da Silva, Luis et al

in Steel & Composite Structures (2003), 3(6), 383-401

Two new formulae for the design of beam-columns at room temperature have been proposed into Eurocode 3, prEN 1993-1-1 (2002), and are the result of great efforts made by two working groups that followed ... [more ▼]

Two new formulae for the design of beam-columns at room temperature have been proposed into Eurocode 3, prEN 1993-1-1 (2002), and are the result of great efforts made by two working groups that followed different approaches, a French-Belgian team and an Austrian-German one. Under fire conditions the prEN 1993-1-2 (structural fire design) presents formulae, for the design of beam-columns based on the prENV 1993-1-1 (1992). In order to study the possibility of having, in part 1-1 and part 1-2 of the Eurocode 3, the same approach, a numerical research was made using the finite element program SAFIR, developed at the University of Liege for the study 4 structures subjected to fire. [less ▲]

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See detailPhotosynthesis and state transitions in mitochondrial mutants of Chlamydomonas reinhardtii affected in respiration
Cardol, Pierre ULg; Gloire, Geoffrey ULg; Havaux, M. et al

in Plant Physiology (2003), 133(4), 2010-2020

Photosynthetic activities were analyzed in Chlamydomonas reinhardtii mitochondrial mutants affected in different complexes (I, III, IV, I + III, and I + IV) of the respiratory chain. Oxygen evolution ... [more ▼]

Photosynthetic activities were analyzed in Chlamydomonas reinhardtii mitochondrial mutants affected in different complexes (I, III, IV, I + III, and I + IV) of the respiratory chain. Oxygen evolution curves showed a positive relationship between the apparent yield of photosynthetic linear electron transport and the number of active proton-pumping sites in mitochondria. Although no significant alterations of the quantitative relationships between major photosynthetic complexes were found in the mutants, 77 K fluorescence spectra showed a preferential excitation of photosystem I (PSI) compared with wild type, which was indicative of a shift toward state 2. This effect was correlated with high levels of phosphorylation of light-harvesting complex II polypeptides, indicating the preferential association of light-harvesting complex II with PSI. The transition to state 1 occurred in untreated wild-type cells exposed to PSI light or in 3-(3,4-dichlorophenyl)-1,1-dimethylurea-treated cells exposed to white light. In mutants of the cytochrome pathway and in double mutants, this transition was only observed in white light in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. This suggests higher rates of non-photochemical plastoquinone reduction through the chlororespiratory pathway, which was confirmed by measurements of the complementary area above the fluorescence induction curve in dark-adapted cells. Photo-acoustic measurements of energy storage by PSI showed a stimulation of PSI-driven cyclic electron flow in the most affected mutants. The present results demonstrate that in C. reinhardtii mutants, permanent defects in the mitochondrial electron transport chain stabilize state 2, which favors cyclic over linear electron transport in the chloroplast. [less ▲]

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