Spatio-cartes des affectations du sol rehaussées d'estompage

in Dessine-moi une carte... (1994)

Spatio-temporal aquatic vegetation patterns in former channels in relation to their isolation from the river Rhine (Eastern France)

in Acta Botanica Gallica : Bulletin de la Société Botanique de France (1995), 142

Spatio-temporal demographic variation and reproductive strategy in rare endemic Oncocyclus irises (Iridaceae) of Lebanon

Poster (2006)

Spatio-temporal localisation of β-actin and γ-actin isoforms during the development of the organ of Corti in rat from the embryonic day 18 (E18) to the post-natal day 25 (P25).

Poster (2011, January 31)

The auditory organ, the organ of Corti (OC), is a highly specialized structure composed by specific cellular types. The sensory cells (HC) are characterized by stereocilia at their apex and are necessary ... [more ▼]

The auditory organ, the organ of Corti (OC), is a highly specialized structure composed by specific cellular types. The sensory cells (HC) are characterized by stereocilia at their apex and are necessary for the sound perception. Theses cells are supported by supporting cells. Based on their morphology and physiology, at least four types of supporting cells can be identified in the OC: inner and outer pillar cells (PC), phalangeal cell and Deiter’s cells. Sensory and supporting cells have cytoskeletons containing β-actin and γ-actin isoforms. In the adult mammalian cochlea, amounts of γ-actin increase and β-actin decrease in the order: outer pillar cells, inner pillar cells, Deiters’ cells and hair cells. In sensory cells, γ-actin appears to be the most prominent component with an apparent γ-actin/β-actin ratio of approximately 2:1 (Hofer et al., 1997). β-actin is present in the cuticular plate but is more concentrated in the stereocilia, especially at the base where the stereocilia insert into the cuticular plate. The amount of γ-actin differs less between these structures, the stereocilia and cuticular plate, although its expression is apparently higher towards the tip of stereocilia and it is the predominant isoform of the hair cell's lateral wall (Furness et al., 2005). The differential subcellular localization of two actin isoforms suggests they may play different functions in auditory organ. In the brain, β-actin is restricted to dynamic structures whereas γ-actin is more ubiquitously distributed and occurs in relatively quiescent regions (Micheva et al., 1998). In the present study, by using confocal microscopy, we investigated the spatio-temporal localisation of β-actin and γ-actin isoforms during the development of the OC in rat from the embryonic day 18 (E18) to the post-natal day 25 (P25). Our results indicated that the labelling for both actin isoforms changed during the OC development. Between E18 and P25, we observed a labelling for β-actin in the apical region of the HC. Between P8 and P25, the feet of PC are also β-actin-positive. Unlike β-actin, between E18 and P10, γ-actin is detected in the basal region of supporting cells. Between P12 and P25, the labelling for γ-actin is preferentially localized in the apical surface of the HC. Our results revealed that during development β-actin isoform preceded γ-actin isoform in the apical region of HC. They also suggest that γ-actin isoform might be involved in attachment of supporting cells with their basal membrane and that β-actin isoform might play a role in PC reorganization during the formation of Corti tunnel. [less ▲]

SPATIO-TEMPORAL LOCALIZATION OF INTERMEDIATE FILAMENTS IN THE ORGAN OF CORTI BETWEEN THE EMBRYONIC DAY 18 (E18) AND THE POST-NATAL DAY 15 (P15) IN RAT

Poster (2009, October 17)

The mammalian auditory organ, the organ of Corti (OC), is composed of mechanosensory hair cells and nonsensory supporting cell types. Based on their morphology and physiology, a least four types of ... [more ▼]

The mammalian auditory organ, the organ of Corti (OC), is composed of mechanosensory hair cells and nonsensory supporting cell types. Based on their morphology and physiology, a least four types of supporting cells can be identified in the OC: inner pillar cell, outer pillar cell, phalangeal cell and Deiter’s cells. The structure of this organ is well reported in adult but its development is still little known. Using antibodies directed against different proteins of intermediate filaments cytoskeleton, we studied the spatial-temporal localization of cytokeratins (typical of epithelial cells) and vimentin (typical of mesenchymal cells) during the differentiation of the OC in rat from the embryonic day 18 (E18) to the postnatal day (P15). Whatever the antibody used, we observed an obvious labelling over the supporting cells after the birth. In particular, an intense labelling is observed in the pillar cells and in the Deiters’ cells at P8 and at P10. These results suggest that the epithelial-mesenchymal transition might be implicated in the opening of Corti’s tunnel between the pillar cells and the formation of the Nuel’s spaces between the Deiters’ cell and their outer hair cells, at P8 and at P10 respectively. [less ▲]

Spatio-temporal localization of the cytoskeleton during auditory organ development in mammalia

Poster (2011, March 31)

The auditory organ, the organ of Corti (OC), is a highly specialized structure composed by specific cellular types. The sensory cells (HC) are characterized by stereocilia at their apex and are necessary ... [more ▼]

The auditory organ, the organ of Corti (OC), is a highly specialized structure composed by specific cellular types. The sensory cells (HC) are characterized by stereocilia at their apex and are necessary for the sound perception. Theses cells are supported by supporting cells. Based on their morphology and physiology, at least four types of supporting cells (SC) can be identified in the OC: inner and outer pillar cells (PC), phalangeal cell and Deiter’s cells. Sensory and supporting cells possess characteristic cytoskeleton proteins in direct relation with their morphological features and their development. Indeed, this organ had morphological changes such as the setting up of the sensory epithelium after the birth or the openings of the Corti’s tunnel at P8 and of the Nuel’s spaces at P10. In the present study, by using confocal microscopy, we investigated the spatio-temporal localization of the three cellular cytoskeletal filaments : microtubules (β-1, 2, 3, 4-tubulin), microfilaments (cytoplasmic β- and γ-actin) and intermediate filaments (CK4, 5, 7, 8, CKpan and vimentin) during the development of the OC in rat from the embryonic day 18 (E18) to the post-natal day 25 (P25). The immunolabellings indicated clearly that β-1, 2, 3-tubulins were only present the SC and nervous fibers during development whereas β-4-tubulin was found firstly in the HC and then in the SC. The two actin-isotypes were detected in the HC apex but were also seen in the PC from P8 to P25 for β-actin isoform and in the basal membrane from E18 to P8 for the γ-actin isoform. All intermediate filament proteins were only found in the SC, especially between P8 and P12. Our results show that the localization of the cytoskeleton proteins during the auditory organ development depends on the cellular type and the developmental stage. A profound modification of cytoskeleton occurs between P8 and P12. [less ▲]

Spatio-temporal localization of the glial fibrillary protein (GFAP) in the spiral ganglia from the 16th embryonic day until the 25th postnatal day in rats

Poster (2011)

Spatio-temporal patterns of preys and wastes moved by ants within the nests

Poster (2010)

Living in society in a restricted and confined nest implies important organisational issues. Ants have to control food supply for the whole colony as well as nest defence but they also have to manage ... [more ▼]

Living in society in a restricted and confined nest implies important organisational issues. Ants have to control food supply for the whole colony as well as nest defence but they also have to manage everyday life tasks such as waste rejection. Within the nest, ants are faced with different items that have to be used or rejected regarding colony needs. We study whether they can discriminate between three types of items (building material, nestmate cadaver or prey) and accordingly adapt the spatio-temporal distribution of these items. Therefore, we used colonies of the ant Myrmica rubra settled in a 2-dimensional space and introduced different items in the nest centre. We show that each item triggers a specific cascade of behaviour. We observed important differences in rejection time: building items were removed within a few minutes and cadavers after a few hours while preys could be kept in the nest for a day or more. Furthermore, the movement of items by ants leads to specific spatio-temporal patterns. Building items were removed with a straight trajectory from the centre to the exit of the nest. Ant cadavers that could bear pathogens showed a trajectory avoiding and moving away from larvae that are potentially more sensitive to diseases. The moving of preys headed an oscillating pattern: these items were alternatively taken on larvae for consumption and then moved away from them, until final rejection. This specific pattern may be due to the coupled effects of groups of ants acting alternatively to feed larvae and reject waste. In the case of cadavers and building items, only undertaking ants may be active. These results suggest that each ant is able to discriminate and interact with each other leading at the collective level to a complex cascade of behaviour. [less ▲]

Spatio-temporal relationships in a primitive space: an attempt to simplify spatio-temporal analysis

in Raubal, Martin; Miller, Harvey; Frank, Andrew (Eds.) et al Fourth International Conference, GIScience 2006 (2006)

Les spatiocartes d'occupation du sol

in Bulletin de la Société Géographique de Liège (2000), 38(2000/1), 63-78

Les spatiocartes d'occupation du sol sont dérivées de la classification d'une ou plusieurs images satellite selon une nomenclature conventionnelle des affectations du sol. En importance, elles constituent ... [more ▼]

Les spatiocartes d'occupation du sol sont dérivées de la classification d'une ou plusieurs images satellite selon une nomenclature conventionnelle des affectations du sol. En importance, elles constituent sans doute le second type de spatiocartes le plus couramment produit, après les spatiocartes en composition colorée. Vis-à-vis de ces dernières, les spatiocartes d'occupation du sol relèvent cependant d'une toute autre logique et procèdent d'une méthodologie très différente. La composition colorée est conçue pour laisser au lecteur le soin d'interpréter l'image en fonction de ses propres centres d'intérêt, et les techniques sélectionnées pour son élaboration doivent précisément favoriser la reconnaissance et l'identification visuelle d'un maximum de détails. La spatiocarte d'occupation du sol, par contre, répond à un objectif précis et déterminé a priori. Tout, depuis la sélection des images sources jusqu'à la sélection des couleurs, en passant par le choix de l'échelle et la fixation de la nomenclature, est dicté par une thématique unique. Les méthodes de classification, elles-mêmes, ne sont pas indépendantes de l'objectif poursuivi. Le but de ce chapitre n'est pourtant pas de discourir sur les multiples algorithmes de classification des images. Une très volumineuse littérature, en constante évolution, y est consacrée (Atkinson & Lewis, 2000, Chin-Teng et al., 2000, Simpson et al., 2000). Les méthodes les plus traditionnelles, relevant de l'interprétation d'images assistée par ordinateur, co-existent avec les méthodes les plus récentes, telles les classifications par réseaux de neurones ou les classifications bayesiennes. L'utilisation de l'une ou l'autre méthode, voire de plusieurs en chaîne, se justifie à l'occasion de tel ou tel cas de figure mais elles n'interfèrent guère sur la préoccupation présente qui consiste à transformer une image classée en une carte. On conçoit dès lors que les traitements dont il sera question se situent en aval du processus de classification proprement dit. Quelques considérations seront pourtant émises sur les préalables de la classification et sur la nature et la qualité de l'image classée, dans la mesure où elles peuvent orienter l'élaboration de la spatiocarte. Par contre, les divers traitements relevant de l'habillage ou de l'impression, communs à toute spatiocarte quelle qu'en soit la facture, sont réservés à des chapitres ultérieurs. De même, quelques opérations complexes, susceptibles d'intervenir dans la réalisation de certaines spatiocartes de l'occupation du sol, mais exigeant un bagage méthodologique important, sont développées dans des chapitres spécifiques auxquels nous renverrons le moment venu. [less ▲]