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See detailBiomarquers d’exposition en milieu terrestre : impact d’hydrocarbures halogénés sur l’activité de trois systèmes enzymatiques chez Drosophila pseudoobscura
Dannau, Marie; Amichot, Marcel; Leenaers, Lionel et al

in Environnement Risques & Santé (2003), 2

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See detailL'image du mois. Sous le pont myocardique coule la coronaire.
ROUSSEAU, Anne-Françoise ULg; MIEVIS, Eric

in Revue Médicale de Liège (2003), 58(10), 601-604

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See detailAvantages sélectifs d'un phénotype hétérochronique. Eco-éthologie des populations pédomorphiques du Triton alpestre, Triturus alpestris (Amphibia, Caudata)
Denoël, Mathieu ULg

Book published by Cahiers d'Ethologie (2003)

Facultative paedomorphosis is a polyphenism that has important evolutionary implications in promoting morphological differentiation and habitat use variation, and has occurred in several urodele species ... [more ▼]

Facultative paedomorphosis is a polyphenism that has important evolutionary implications in promoting morphological differentiation and habitat use variation, and has occurred in several urodele species throughout the world. Several hypotheses based on life-history theory have been proposed to explain the wide range of habitats where facultative paedomorphosis occurs, suggesting multiple causes. In populations experiencing facultative paedomorphosis, some individuals metamorphose and mature (metamorphs), while others attain sexual maturity while still retaining traits of larval somatic morphology (paedomorphs). The paedomorphic process by which the development of somatic and reproductive organs is shifted between related individuals is assumed to significantly contribute to macro-evolutionary processes. Indeed, it implies large phenotypic variations in the absence of deep genetic changes. A way to explain the importance of these developmental heterochronies is to show their adaptive value in the micro-evolutive stage. The aim of this thesis is to determine the advantages gained by an individual that adopts a paedomorphic developmental pathway rather than a metamorphic one. To do this, we studied five factors: habitat use; resource partitioning; age and size structures; sexual compatibility; and the effect of environmental factors. The ecological and ethological characteristics of several mixed populations (composed of both paedomorphic and metamorphic individuals) of the Alpine newt Triturus alpestris (Amphibia, Salamandridae) were investigated from 1997 to 2000. These populations were located in France, Italy and Greece. The habitats occupied by dimorphic populations of the Alpine newt are highly variable. We have found the two morphs in syntopy in deep permanent lakes, and in small shallow and temporary ponds. Aquatic habitats were surrounded by various terrestrial habitats. As a result, it was not possible to correlate any particular environment type with the maintenance of the polymorphism in natural populations. The only common trait of the paedomorphic populations was that they were located at the southern margin of the range of the species (Italy, the Balkan peninsula, and southeastern France). Such a restriction of the distributional range of paedomorphosis suggests that this trait is maintained by genes which are shared only by these populations. Such a restriction may be due to Holocene colonizations from Pleistocene refugia, in which case paedomorphosis may have appeared in these refugia during the last glaciations. Nevertheless, as long as the phylogeny of the group remains uncertain, we cannot reject the possibility of an earlier origin of paedomorphosis. The two morphs primarily differed in space use and feeding habits. These differences were particularly marked in deep alpine aquatic habitats, where the paedomorphs occupy deep waters devoid of competitors, such as fish. In such waters, the paedomorphs were more abundant on the bottom and in the water column, whereas the metamorphs mainly occupied the water surface and shore. The paedomorphs primarily ingested plankton, while the metamorphs mainly foraged on terrestrial prey that had fallen on the water surface. Although these feeding habits depend on newt habitats - plankton being more abundant in the water column, and terrestrial prey at the water surface - the trophic spectrum in each habitat still differed. While the energetic values of the prey eaten by the two morphs strongly differed, by ingesting a large number of planktonic organisms, the paedomorphs attained similar or even larger caloric intake rates than metamorphs. The paedomorphs' superior body condition suggests that they may have higher long-term success than the metamorphs. Differences in body condition may also reflect the terrestrial life habit of the metamorphs, since metamorphosed individuals are able to avoid competition with reproductive adults and larvae by leaving the water. In the paedomorphic populations, several size-structured cohorts of larvae coexist, and competition among these cohorts is lowered by size-selective predation, since small larvae catch smaller prey than larger larvae and paedomorphs. Although this difference in diet was in part due to gape-size limitation, the gilled individuals also size-selected prey among a range of catchable items. Resource partitioning then favoured the coexistence of the two adult morphs, and their gilled descendants, which coexist with them. The two morphs also differed in feeding performance. Whereas the paedomorphs were better predators than metamorphs on water fleas, metamorphs were more adept at capturing large terrestrial invertebrates (flies). These differences in feeding performances were caused by the morphological particularities of the two morphs. Paedomorphs had a fish-like feeding structure with a unidirectional water flow passing through the oral cavity, and then being expelled through gill slits on the posterior side of the head. In contrast, metamorphs had a smaller oral cavity and a bidirectional water flow due to closed gill slits. Although the metamorphic structure produces less suction, it allows for catching bigger prey because of a larger gape-size (biting rather than sucking). Our measures of feeding performances confirmed the data from natural populations, with each of the morphs preferentially eating their predicted prey. The particular use of micro-habitats by the two morphs is also in agreement with optimality models predicting predation in the more profitable patches. In the Alpine newt, paedomorphosis can be produced by two main processes: neoteny and progenesis. In some populations, the two morphs reached sexual maturity at the same age (neoteny); in other populations, sexual maturity was reached earlier by paedomorphs (progenesis). Progenesis was observed in unstable water habitats. Pond drying suppressed the possibility of late maturation, which is characteristic of a neotenic developmental pathway. On the other hand, the precocious sexual maturation of paedomorphs favoured the fast colonization of new habitats, owing to a high intrinsic rate of natural increase. Neoteny was typical of permanent waters with harsh constraints on growth. By forgoing metamorphosis, larvae also avoid the cost of changing of structure (decrease in body weight in our experiments). Progenetic paedomorphosis appears then as a major trait that can be selected due to the advantages of earlier maturation. The two morphs are sexually compatible; thus, metamorphs can "exchange" genes with paedomorphs at each generation. While the two morphs markedly differ in their secondary sexual characteristics, females did not show any preference related to these characteristics. The absence of sexual isolation between the morphs shows that they are not involved in a sympatric speciation process. The maintenance of the polymorphism is more advantageous than the formation of two isolated species. Paedomorphosis occurs in aquatic habitats where total drying can occur, and where the maintenance of facultative paedomorphosis is maintained by metamorphs that have paedomorphic genes but do not (permanently) express them. In such habitats, the sexual isolation of the two morphs would lead to the extinction of paedomorphosis in the event of pond drying or similar catastrophe. Because the environment can modify the ontogenetic pathway, paedomorphosis in the Alpine newt can be considered a polyphenism. Indeed, restricting the amount of water or food available induces paedomorphs to metamorphose. The marking of individual paedomorphs in a natural population proved that metamorphosis also occurs in the field. However, salamander density and progressive drying of aquaria did not have any apparent effect on paedomorph metamorphosis. When the possibility of a short migration across dry land was given, paedomorphs moved towards an available water basin and maintained their larval somatic characters during the migrations. By being able to migrate on land towards permanent water, paedomorphs are able to retain a feeding morphology that favors them in microhabitats where plankton is abundant. Facultative paedomorphosis in the Alpine newt allows populations to cope with environmental variability, and is adaptive in allowing precocious maturation or a larger use of resources in spatially heterogeneous environments. Thus, it is not surprising that paedomorphosis can evolve in such dissimilar environments as lowland temporary ponds and highland deep lakes. In such places, paedomorphosis appears to be the best solution as long as fish predation is relaxed. The introduction of fish throughout Europe is thus a serious problem, and has resulted in the extinction of several large paedomorphic populations. If this trend is not stopped rapidly, paedomorphosis in the Alpine newt - and in other species - will belong to the past. [less ▲]

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See detailApparition et maintien de la turbulence chez les enfants de 3 à 10 ans. Quelles solutions?
Born, Michel ULg; Boët, Sylvie

in Drenkhahn, Kirstin (Ed.) Violence juvénile : nouvelles formes et stratégies locales - expéciences à l'est et à l'ouest (2003)

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See detailLa violence des jeunes en regard des nouvelles socialisations
Born, Michel ULg

in Violence juvénile : nouvelles formes et stratégies locales - expériences à l'est et à l'ouest (2003)

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See detailFormasup : un 3e cycle en pédagogie universitaire qui met en oeuvre sept clés méthodologiques au service du déploiement de pratiques de qualité en EAD
Poumay, Marianne ULg

in L'université au service de l'apprentissage : A quelles conditions ? (2003)

L'article présente le curriculum "Formasup" (Master Complémentaire depuis 2007) et les sept principes méthodologiques qui présidaient à son organisation en 2003.

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See detailPréface à "Adolescents en difficultés"
Born, Michel ULg

in Collectif (Ed.) Adolescents en difficultés (2003)

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See detailA la recherche d'une langue perdue
Boutier, Marie-Guy ULg

in Bulletin de la Commission Royale de Toponymie et de Dialectologie = Handelingen van de Koninklijke Commissie voor Toponymie en Dialectologie (2003), 75

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See detailPhysiology of reproduction and endocrinology in cervids. A review
Drion, Pierre ULg; Hanzen, Christian ULg; Wirth, Delphine - in memoriam et al

in Annales de Médecine Vétérinaire (2003), 147(5), 291-313

Knowledge about cervids are rapidly growing. This work aims to present the more recent scientific information on reproductive physiology and endocrinology of the cervids: anatomy of the genital tract ... [more ▼]

Knowledge about cervids are rapidly growing. This work aims to present the more recent scientific information on reproductive physiology and endocrinology of the cervids: anatomy of the genital tract, length of breeding season, parameters and endocrinology of the reproductive cycle, endocrinology of pregnancy. It also aims to highlight differences between cervids and domestic ruminants such as embryonic diapause observed in Capreolus capreolus. [less ▲]

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See detailAtypical recurrent varicella in 4 patients with hemopathies.
Nikkels, Arjen ULg; Simonart, Thierry; Kentos, Alain et al

in Journal of the American Academy of Dermatology (2003), 48(3), 442-7

Relapsing varicella may occur in children with HIV infection and more rarely in younger adults. Our aim was to report unusual clinical, histologic, and virologic aspects of 4 elderly patients with ... [more ▼]

Relapsing varicella may occur in children with HIV infection and more rarely in younger adults. Our aim was to report unusual clinical, histologic, and virologic aspects of 4 elderly patients with malignant hemopathies who had an unusual form of recurrent varicella develop. Conventional microscopy, immunohistochemistry, and in situ hybridization were applied to smears and skin biopsy specimens. The patients presented a few dozen, scattered, large, papulovesicular lesions with central crusting. No zoster-associated pain or dermatomal distribution of the lesions was noted. Conventional microscopy revealed vascular changes and epidermal alterations typical for alpha-herpes virus infection. The varicella zoster virus major viral envelope glycoproteins gE and gB, and the immediate-early varicella zoster virus IE63 protein and the corresponding genome sequence for gE were detected on Tzanck smears; they were localized in endothelial cells and keratinocytes on skin biopsy specimens. The varicella zoster virus infection in endothelial cells, the vascular involvement, and the widespread distribution of the lesions suggest that the reported eruptions are vascular rather than neural in origin. These findings invalidate the diagnosis of herpes zoster but strongly support the diagnosis of recurrent varicella in an indolent and yet unreported presentation. Furthermore, these eruptions differ from relapsing varicella in children and young adults by the age of the patients, the paucity of clinical lesions, the larger diameter of the lesions and their peculiar clinical aspect, the significantly longer time interval between primary varicella and the recurrence, the prolonged healing time of the lesions, their mild disease course, and the fact that all the lesions are in the same stage of development. [less ▲]

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See detailIdentification de la place des chercheurs et des praticiens dans la recherche sur l’intervention dans les APS
Cloes, Marc ULg

in Cloes, Marc (Ed.) L’intervention dans les Activités physiques et sportives : rétro/perspectives (2003)

La recherche sur l'Intervention dans les Activités Physiques et Sportives (APS) est a donné une place privilégiée aux chercheurs dans le sens où ces derniers ont guidé majoritairement les choix des thèmes ... [more ▼]

La recherche sur l'Intervention dans les Activités Physiques et Sportives (APS) est a donné une place privilégiée aux chercheurs dans le sens où ces derniers ont guidé majoritairement les choix des thèmes de recherche et laissé aux sujets un rôle secondaire. L'évolution actuelle met clairement en évidence le besoin de les impliquer davantage. En se basant sur une analyse de la littérature spécifique au domaine des APS, ce texte tente ainsi de faire ressortir l'intérêt des recherche-action. [less ▲]

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See detailAlcoolisme ou aldehydisme : Role de l'acetaldehyde dans les effets psychotropes de l'alcool
Quertemont, Etienne ULg

in Alcoologie et Addictologie (2003), 25(1), 33-39

De récentes études ont suggéré que l’acétaldéhyde, premier produit du métabolisme de l’éthanol, participe aux effets psychotropes résultant de la consommation d’alcool. L’acétaldéhyde semble ... [more ▼]

De récentes études ont suggéré que l’acétaldéhyde, premier produit du métabolisme de l’éthanol, participe aux effets psychotropes résultant de la consommation d’alcool. L’acétaldéhyde semble particulièrement impliqué dans les effets renforçants de l’éthanol, ce qui suggère un rôle important pour ce métabolite dans l’abus d’alcool et l’alcoolisme. Cette mise au point passe en revue les preuves expérimentales qui tendent à démontrer le rôle de l’acétaldéhyde dans les effets psychotropes de l’alcool. Les études animales et humaines indiquent que l’acétaldéhyde exerce une action renforçante plus puissante que l’éthanol dans le cerveau. Au contraire, il semble que l’accumulation d’acétaldéhyde dans le sang périphérique provoque des effets désagréables et une aversion pour l’alcool. Les effets hédoniques de l’acétaldéhyde seraient donc déterminés par le lieu, central ou périphérique, de son accumulation principale. Toutefois, l’acétaldéhyde ne doit pas être considéré comme le seul principe actif responsable de tous les effets psychotropes de l’éthanol. Plusieurs études ont par exemple démontré que l’acétaldéhyde ne participe pas significativement aux effets subjectifs de l’éthanol. Si l’acétaldéhyde exerce effectivement un rôle dans les effets renforçants de l’éthanol, il ne doit donc pas être tenu pour responsable de tous les effets pharmacologiques de la consommation d’alcool. [less ▲]

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See detailThe use of blood pepsinogen as a biomarker of the integrity of the porcine gastric mucosa. 2. Measurements of blood pepsinogen and its usefull in the detection of gastric diseases
Banga-Mboko, Henri; Godeau, Jean-Marie ULg; Drion, Pierre ULg et al

in Annales de Médecine Vétérinaire (2003), 147(2, APR-MAY), 95-104

Pepsinogen is one component of the gastric juice which participes in the digestion. This macromolecule enters the blood circulation in a small measurable quantities in healthy subjects. Therefore, blood ... [more ▼]

Pepsinogen is one component of the gastric juice which participes in the digestion. This macromolecule enters the blood circulation in a small measurable quantities in healthy subjects. Therefore, blood pepsinogen is claimed to be an indicator of the integrity of the gastric mucosa. This paper was written to review the use of porcine in the diagnostic of stomach ulcers and Hyostrongylus rubidus infection. The methods of measurement of blood pepsinogen and the diagnostic values are discussed. [less ▲]

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See detailMycotoxins in stored Barley (Hordeum vulgare) in Tibet Autonomous Region (People’s Republic of China.
Haubruge, Eric ULg; Chasseur, Camille

in Mountain Research & Development (2003), 23

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See detailL’enseignement universitaire demain. Le cas de la Belgique francophone
Merenne-Schoumaker, Bernadette ULg

in Géographes Associés, AFDG (2003), (27), 63-65

Courte présentation de la situation de la géographie dans le monde universitaire francophone de Belgique au moment de la Réforme de Bologne

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See detailDu Séminaire de Géographie au Département de Géographie, Cent ans de géographie à l’Université de Liège, 1903-2003
Merenne-Schoumaker, Bernadette ULg

in Bulletin de la Société Géographique de Liège (2003), (43), 3-17

100-year history of teaching and research in geography at the University of Liege

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See detailLa Société géographique de Liège
Merenne-Schoumaker, Bernadette ULg

in Bulletin de la Société Géographique de Liège (2003), (43), 185-194

75-year history of the Geographical Society of Liege

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See detailInfluence of a nonlinear reference temperature profile on oscillatory Benard-Marangoni convection.
Dondlinger, M.; Colinet, P.; Dauby, Pierre ULg

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2003), 68(6 Pt 2), 066310

We analyze oscillatory instabilities in a fluid layer of infinite horizontal extent, heated from above or cooled from below, taking into account the nonlinearity of the reference temperature profile ... [more ▼]

We analyze oscillatory instabilities in a fluid layer of infinite horizontal extent, heated from above or cooled from below, taking into account the nonlinearity of the reference temperature profile during the transient state of heat conduction. The linear stability analysis shows that a nonlinear reference temperature profile can have a strong effect on the system, either stabilizing or destabilizing, depending on the relative importance of buoyancy and surface tension forces. For the nonlinear analysis we use a Galerkin-Eckhaus method leading to a finite set of amplitude equations. In the two-dimensional (2D) case, we show the solution of these amplitude equations are standing waves. [less ▲]

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