Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
See detailDistribution and quantification of tension wood in poplar shoote
Jourez, Benoît ULg; Leclercq, André

Conference (1996)

Detailed reference viewed: 18 (4 ULg)
Full Text
See detailDistribution and quantitative importance of chitin in animals
Jeuniaux, Charles ULg

Scientific conference (1978)

Using a specific and quantitative enzymatic-identification procedure, the polysaccharide chitin has been found in a wide range of animal species. It is used by protozoans, mainly ciliates, to build up ... [more ▼]

Using a specific and quantitative enzymatic-identification procedure, the polysaccharide chitin has been found in a wide range of animal species. It is used by protozoans, mainly ciliates, to build up cyst walls. It also constitutes the bulk of the stalks or stems of most hydrozoan colonies, but it is rarely produced by Scyphozoa (jellyfishes) and Anthozoa, and is absent in sponges. Chitin is the main structural polysaccharide of most invertebrates belonging to the Protostomia. Arthropods are the best known and most important chitin-producing animals ; the dry organic matter of their cuticles can contain up to 80% chitin. Besides the arthropods, relatively large amounts of chitin may be found in the setae of annelids (from 20 to 38% of dry weight), in the skeleton of the colonies of Bryozoa and in the shells and other structures (jaws, radulae, gastric shield) of many mollusc species (up to 7% of the dry organic matter in gastropods and bivalve shells, and up to 26% in cephalopods). Chitin is only absent in free and parasitic flatworms (Platyhelminthes), nemerteans, sipunculids and leeches. In some other groups, such as nematodes and rotifers, chitin is present only in the egg envelopes. Chitin synthesis has never been observed in echinoderms or vertebrates, but the tubes of some Pogonophora contain 33% chitin, while tunicates secrete a chitinous peritrophic membrane. From an ecological point of view, besides crustaceans and molluscs, marine benthic animals are a rich source of chitin. Despite their small size, bryozoan and hydrozoan colonies yield a large biomass with relatively substantial amounts of chitin. Some bryozoans play a role in the epuration of fresh water and produce a considerable biomass of chitin-containing colonies as well. The proportion of "free" chitin, i.e., not bound to other organic molecules, is generally low (less than 10%), although it can account for 80% of the total chitin in mollusc shells. [less ▲]

Detailed reference viewed: 77 (1 ULg)
Full Text
Peer Reviewed
See detailDistribution and Regulation of Estrogen-2-Hydroxylase in the Quail Brain
Balthazart, Jacques ULg; Stoop, R.; Foidart, Agnès ULg et al

in Brain Research Bulletin (1994), 35(4), 339-45

The anatomical distribution and endocrine regulation of the estrogen-2-hydroxylase activity were investigated in the brain of adult male and female Japanese quail. Significant levels of enzymatic activity ... [more ▼]

The anatomical distribution and endocrine regulation of the estrogen-2-hydroxylase activity were investigated in the brain of adult male and female Japanese quail. Significant levels of enzymatic activity were detected in all brain regions that were studied, but the highest levels were observed in preoptic and hypothalamic brain nuclei that are known to contain high levels of aromatase activity. These data are consistent with previous results suggesting that the placental aromatase is also responsible for the estrogen-2-hydroxylase activity. However, there is a marked sex difference and a control by T of aromatase activity in the quail brain, and no such difference in 2-hydroxylase activity could generally be detected except in the VMN. Further studies will be needed to know whether the previously published conclusions concerning the human placenta also apply to the brain. The present data are consistent with the idea that estrogens formed locally in the brain by testosterone aromatization could affect reproduction by interfering with the catecholaminergic transmission after being metabolized into catechol-estrogens. [less ▲]

Detailed reference viewed: 15 (0 ULg)
Full Text
See detailDistribution and robustness of a distance-based multivariate coefficient of variation
Aerts, Stéphanie ULg

Poster (2014, November)

When one wants to compare the homogeneity of a characteristic in several popula- tions that have di erent means, the advocated statistic is the univariate coe cient of variation. However, in the ... [more ▼]

When one wants to compare the homogeneity of a characteristic in several popula- tions that have di erent means, the advocated statistic is the univariate coe cient of variation. However, in the multivariate setting, comparing marginal coe cients may be inconclusive. Therefore, several extensions that summarize multivariate relative dispersion in one single in- dex have been proposed in the literature (see Albert & Zhang, 2010, for a review). In this poster, focus is on a particular extension, due to Voinov & Nikulin (1996), based on the Mahalanobis distance between the mean and the origin of the design space. Some arguments are outlined for justifying this choice. Then, properties of its sample version under elliptical symmetry are discussed. Under normality, this estimator is shown to be biased at nite samples. In order to overcome this drawback, two bias corrections are proposed. Moreover, the empirical estimator also su ers from a lack of robustness, which is illustrated by means of in uence functions. A robust counterpart based on the Minimum Covariance Determinant estimator is advocated. [less ▲]

Detailed reference viewed: 58 (10 ULg)
See detailDistribution and variations of pCO2 in subantarctic waters of the Kerguelen Archipelago
Delille, Bruno ULg; Delille, D.; Fiala, M. et al

Poster (2000, July)

Detailed reference viewed: 9 (0 ULg)
Full Text
See detailDistribution assessment of endangered Lepilemur in northwestern Madagascar
Wilmet, Leslie ULg; Vermeulen, Cédric ULg; Beudels-Jamar, Roseline

Scientific conference (2013, October 21)

Detailed reference viewed: 30 (5 ULg)
Full Text
Peer Reviewed
See detailDistribution d’adhésines potentielles au sein de souches d’Escherichia coli entérohémorragiques de sérogroupes O26
Bardiau, Marjorie ULg; Labrozzo, Sabrina; Mainil, Jacques

Poster (2008, September)

Detailed reference viewed: 7 (0 ULg)
Full Text
Peer Reviewed
See detailDistribution de 8 espèces végétales endémiques du Katanga (R.D.Congo) le long d'un gradient de cuivre et de cobalt
Boisson, Sylvain ULg; Lebrun, Julie ULg; Mahy, Grégory ULg

Poster (2013, November 06)

Au sud de la province du Katanga (R.D.Congo), se développe une végétation unique sur des sols recouvrant une centaine d’affleurements de cuivre et de cobalt parmi les plus importants au monde (Arc ... [more ▼]

Au sud de la province du Katanga (R.D.Congo), se développe une végétation unique sur des sols recouvrant une centaine d’affleurements de cuivre et de cobalt parmi les plus importants au monde (Arc cuprifère katangais). Le paysage de cette région est composé de collines isolées les unes des autres et présentant des communautés végétales distinctes selon la concentration en éléments traces métalliques du sol. Les savanes steppiques se retrouvent sur des sols faiblement contaminés tandis que les pelouses sont inféodées aux sols pouvant être contaminés à des teneurs avoisinant les 10 000 mg.kg-1 de cuivre et 1000 mg.kg-1 de cobalt. Plus de 600 espèces d’angiospermes métallophytes y sont retrouvées dont 32 vivant exclusivement sur des sols contaminés (endémiques strictes). Ces espèces présentent des adaptations physiologiques et biologiques leur permettant de tolérer les concentrations exceptionnelles dans le sol. Certaines d’entre-elles ont d’ailleurs été identifiées comme des hyperaccumulatrices de cuivre et/ou de cobalt. Le caractère unique de la plupart des espèces endémiques de cette flore est aujourd’hui menacé par les activités minières intenses dans la province. Ces espèces représentent pourtant des ressources génétiques de grands intérêts pour développer des stratégies de restauration et de remédiation des sites pollués par leur rôle potentiel en phytostabilisation des sols. L’objectif de l’étude est de caractériser la niche écologique réalisée de 8 espèces endémiques le long du gradient de cuivre et cobalt en vue d’adapter les stratégies de conservation et de restauration des espèces. Les espèces étudiées sont Triumfetta likasiensis, Lopholaena deltombei, Tinnea coerulea var. obovata, Sopubia neptunii, Basananthe kisimbae, Barleria lobelioides, Commelina zigzag, Euphorbia cupricola. Pour chaque espèce, 3 sites ont été prospectés en faisant un transect de 2 m de large le long des gradients métalliques et en identifiant tous les individus de l’espèce. Ensuite, 5 individus ont été sélectionnés parmi le nombre total d’individus comptés : 2 extrêmes, 1er quartile, 1 médian, 3ème quartile. Pour chacun d’eux, un quadrat d’un mètre carré y a été centré au sol et le nombre d’individus de l’espèce dénombrés. Un échantillon de sol composite a ensuite été prélevé entre 0 et 15 cm de profondeur afin de déterminer les teneurs en cuivre et cobalt par une spectrométrie d’absorption atomique dans la flamme à partir de l’extrait NH4-Acétate-EDTA du sol. Les niches écologiques réalisées ont été modélisées pour chaque métal par la méthode d’estimation des noyaux avec le logiciel R 3.0.1 (package ‘vioplot’). Les résultats montrent que les niches écologiques de ces espèces endémiques se répartissent entre 50 et 11 000 mg.kg-1 de sol pour le cuivre et 4 et 1500 mg.kg-1 de sol pour le cobalt. Six espèces se situent dans des concentrations inférieures à 100 mg.kg-1 le long du gradient de cobalt. Le long du gradient de cuivre, deux espèces ont des optima écologiques supérieurs à 3000 mg.kg-1. La niche écologique de B. kisimbae est la plus étroite avec un optimum environnant les 200 mg Cu.kg-1 et 50 mg Co.kg-1. L’espèce S. neptunii est présente sur l’entièreté du gradient de cobalt et est retrouvée dans les concentrations élevées. La variation des niches écologiques le long des gradients métalliques indique que les stratégies de conservation doivent être adaptées selon les espèces à conserver. Dans cette étude, 4 des 8 espèces pourraient être conservées sur un sol contaminé à 500 mg Cu.kg-1 et 30 mg Co.kg-1. Pour les autres, il est indispensable de mettre en place les stratégies de conservation en considérant, dans un premier temps, les espèces au cas par cas. [less ▲]

Detailed reference viewed: 90 (9 ULg)
Full Text
Peer Reviewed
See detailDistribution de l'alginase chez les Mollusques et d'autres invertébrés
Franssen, J.; Jeuniaux, Charles ULg

in Archives Internationales de Physiologie et de Biochimie (1962), 70(1), 301-303

Detailed reference viewed: 6 (0 ULg)
Full Text
See detailDistribution des cas européens de myopathie atypique de 2003 à 2013 : maladie endémique ou émergente Pratique vétérinaire équine
Patarin, Florence; Pitel, Christel; Votion, Dominique ULg

in Pratique Vétérinaire Equine (2014), 46(182), 6-10

Detailed reference viewed: 15 (6 ULg)
Full Text
See detailDistribution des chitinases chez les mammifères rongeurs
Frankignoul, M.; Jeuniaux, Charles ULg

in Annales de la Société Royale Zoologique de Belgique (1964), 95

The distribution of chitinase secretion has been studied in four species of Rodents. The biosynthesis of this enzymes is only performed by the gastric mucosa ; the pancreas seems to be unable to secrete ... [more ▼]

The distribution of chitinase secretion has been studied in four species of Rodents. The biosynthesis of this enzymes is only performed by the gastric mucosa ; the pancreas seems to be unable to secrete chitinase, as far as Rodents are concerned. In the cases of the Rat and the Mouse, the individual variability may be reduced to a minimum by using animals of the same age, sex and size, sacrificed at the same moment with respect to the last meal. Among the species so far studied, the Guinea-pig is the only one which does not secrete a gastric chitinase. The Hamster secretes only small amounts of chitinase, while Rats and Mice, which are omnivorous, exhibit an important gastric chitinase secretion. In the latter animals, the chitinase contents of the gastric mucosa are as high as in some Reptiles or insectivorous Birds. These observations confirm the existence of a correlation between the ability of a given species to synthetize chitinase and the feeding habits of this species. [less ▲]

Detailed reference viewed: 3 (0 ULg)
See detailDistribution des efforts dans les assemblages
Jaspart, Jean-Pierre ULg

in Actes de la Journée d'études sur les assemblages dans la construction métallique (1995)

Detailed reference viewed: 26 (0 ULg)
Full Text
Peer Reviewed
See detailLa distribution des industries dans une région : des images multiples
Merenne-Schoumaker, Bernadette ULg; Devillet, Guénaël ULg

in Bulletin de la Société Géographique de Liège (2001), 40

How to apprehend the industrial distribution in a region ? How to analyse their pattern ? Such are the two main questions discussed in this paper which tries to give an answer by a progress in five steps ... [more ▼]

How to apprehend the industrial distribution in a region ? How to analyse their pattern ? Such are the two main questions discussed in this paper which tries to give an answer by a progress in five steps : thinking about the choice of indicators, thinking about the choice of the spatial scale, making or not a distinction between industrial hranchs or types, integreting or not the temporal changes, testing a typology. Through all the images that have been produced, the relativity of the points of view as well as their partial approach of the studying phenomenon are showed, which indicates that both « prudence » and « modesty » are necessary in all researchs trying to analyse the structures of the territories. [less ▲]

Detailed reference viewed: 79 (18 ULg)
See detailDistribution des leucocytes dans la tonsille nasopharyngée chez le chien indemne de maladie respiratoire
Kersnak-Bouchet, Emilie

Master of advanced studies dissertation (2006)

Detailed reference viewed: 28 (0 ULg)
Full Text
Peer Reviewed
See detailDistribution des propriétés morphologiques et chimiques d’un sol le long d’un versant forestier
Deraedt, Deborah ULg; Degré, Aurore ULg; Colinet, Gilles ULg

in Revue Forestière Française (2014), 2014(4),

Plant productivity is partly dependent on soil fertility, which is why it is important to know the distribution of the chemical and morphological properties of the soil. The study was conducted at an ... [more ▼]

Plant productivity is partly dependent on soil fertility, which is why it is important to know the distribution of the chemical and morphological properties of the soil. The study was conducted at an experimental site located on a steep forested slope planted with conifers. Consequently, prior to the study of variations in soil and vegetation characteristics over time, we analysed the chemical and morphological properties along the slope. Eight pits were dug and sampled by horizon. Root density, bulk density and stone content measurements were performed as well as the analysis of the soil chemical properties (pH, K, Mg, Na, Ca and P content). The results confirm the significance of vertical differentiation as one moves along the profile. [less ▲]

Detailed reference viewed: 62 (26 ULg)
See detailDistribution du genre Leclercqia au Dévonien: implications paléogéographiques.
Meyer-Berthaud, Brigitte; Gerrienne, Philippe ULg; Fairon-Demaret, Muriel ULg et al

Conference (2002)

Detailed reference viewed: 16 (0 ULg)