Landscape structure indicators as a key feature in habitat selection : an operational approach to conservation planning

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Peptide and Peptide-Like Modulators of 20S Proteasome Enzymatic Activity in Cancer Cells

The involvement of the ubiquitin–proteasome pathway in the degradation of critical intracellular regulatory proteins suggested a few years ago the potential use of proteasome inhibitors as novel therapeutic agents being applicable in many different disease indications, and in particular for cancer therapy. This article reviews recent salient medicinal chemistry achievements in the design, synthesis, and biological characterization of both synthetic and natural peptide-like proteasome inhibitors, updating recent reviews on this class of agents. As shown herein, different compound classes are capable of modulating the subunit-specific proteolytic activities of the 20S proteasome in ways not previously possible, and one of them, bortezomib, has provided proof-of-concept for this therapeutic approach in cancer clinical settings

Identification of Genes That Promote or Antagonize Somatic Homolog Pairing Using a High-Throughput FISH–Based Screen

The pairing of homologous chromosomes is a fundamental feature of the meiotic cell. In addition, a number of species exhibit homolog pairing in nonmeiotic, somatic cells as well, with evidence for its impact on both gene regulation and double-strand break (DSB) repair. An extreme example of somatic pairing can be observed in Drosophila melanogaster, where homologous chromosomes remain aligned throughout most of development. However, our understanding of the mechanism of somatic homolog pairing remains unclear, as only a few genes have been implicated in this process. In this study, we introduce a novel high-throughput fluorescent in situ hybridization (FISH) technology that enabled us to conduct a genome-wide RNAi screen for factors involved in the robust somatic pairing observed in Drosophila. We identified both candidate “pairing promoting genes” and candidate “anti-pairing genes,” providing evidence that pairing is a dynamic process that can be both enhanced and antagonized. Many of the genes found to be important for promoting pairing are highly enriched for functions associated with mitotic cell division, suggesting a genetic framework for a long-standing link between chromosome dynamics during mitosis and nuclear organization during interphase. In contrast, several of the candidate anti-pairing genes have known interphase functions associated with S-phase progression, DNA replication, and chromatin compaction, including several components of the condensin II complex. In combination with a variety of secondary assays, these results provide insights into the mechanism and dynamics of somatic pairing

Ecologie du paysage et dynamique végétale post-culturale en zone de montagne

The concepts of landscape ecology and a system of geographic information were used to study the vegetation dynamics and the landscape transformation in post-cultural mountainous systems. On the adret of the Saint-Michel-de-Maurienne Savoie affected by the agricultural undervalue, two sites of 150 ha have been chosen, each one of them belonging to a different geographic and pedological unit. Four diachronic maps of the vegetation physionomy was made and digitalized based on old aerial pictures. The landscape dynamics was treated with transition matrices. The evolution of the landscape structure was also studied through landscape diversity, complexity and heterogeneity indexes. A phytoecological study based on stratified samplings after the abandon of the plots has permitted a characterization of the main vegetation groups encountered. The relationships between the landscape dynamics, the landscape structure and the different types of vegetation are discussed as are the differences between the two sites from a landscape and a stational standpoint. / Les concepts de l'écologie du paysage et un système d'information géographique sont utilisés pour étudier la dynamique de la végétation et la transformation des paysages dans des systèmes montagnards post-culturaux. Sur l'Adret de Saint-Michel-de-Maurienne Savoie touché par la déprise agricole ont été sélectionnés deux secteurs d'étude de cent cinquante hectares appartenant chacun à une unité géo-pédologique différente. Quatre cartes diachroniques de la physionomie végétale à partir d'anciennes photographies aériennes ont été élaborées et numérisées. La dynamique paysagère est appréhendée au moyen des matrices de transition. L'évolution de la structure du paysage est également étudiée en particulier par les indices de diversité, de complexité et d'hétérogénéité du paysage. Une étude phyto-écologique fondée sur un échantillonnage stratifié suivant la date d'abandon des parcelles a permis une caractérisation des principaux groupements de végétation rencontrés. Les relations entre la dynamique paysagère, la structure du paysage et les types de végétation correspondants sont discutés, ainsi que les différences mises en exergue entre les deux secteurs d'étude, aussi bien au niveau du paysage qu'au niveau stationnel

Structuration et rôle économique du bocage du Champsaur. Aspects méthodologiques

This article presents the methodology used to study the biological characteristics and the spatial structuring of the Champsaur "bocage". This approach is based on systematic sampling and multivariate analysis and the digitisation and spatial referencing of the resulting data-base using GIS (Arc-Info) / Cet article présente la méthodologie retenue pour l'étude des caractéristiques biologiques et de structuration spatiale du bocage du Champsaur. Cette démarche s'appuie sur la technique des relevés systématiques et de leur analyse statistique multivariée puis sur une numérisation et spatialisation, grâce au SIG Arc-info, de la base de données ainsi constituée

Use of a geographic information system (ARC-INFO) for studying ligneous recolonisation in fallow land countries (French Alps)

Agricultural devalorization in mountain areas has modified the ecological equilibrium. Today, abandoned lands are covered of shrubs. The ARC-INFO system is very useful in the study of recolonization dynamics which requires a comparison of physical, ecological and economic data. / La déprise agricole en montagne a modifié l'équilibre écologique. Aujourd'hui les terrains en friche sont couverts d'une végétation arbustive. L'utilisation du système ARC-INFO est d'une grande utilité pour l'étude de la dynamique de la végétation qui exige une comparaison des données physiques, écologiques et économiques

Evolution of the mosaic patterns in a mountain lanscape (French Alps) in relation to ecological and biological diversity

In the French Alps, an area of 5000 ha in the Maurienne valley hit by the cultivated land running fallow was analysed using a GIS. Landscape pattern evolution of two ecological units (150 ha each) was determined over a 250 year period (1732-1988). The method used consist of a spatial analysis (landscape level) of physionomic fallow vegetation stages evolution. At a lower level (agricultural plot) biological mechanisms influencing the vegetation dynamics were studied (plant-humus relation). On the two units, land abandonment has increasd landscape heterogeneity from 1732 to 1953. After 1953 and particulary from 1970 to 1988, heterogeneity decreases, but not at the same rate on the two units. Influence of ecological conditions (water supply) and land use abandonment process are presented. Relations between landscape heterogeneity and ecological or biological diversity are discussed. / Dans les Alpes Françaises, un bassin versant de 5000 ha, situé dans la vallée de Maurienne, et touché par la déprise agricole, a été étudié par le biais d'un SIG. L'évolution des caractéristiques paysagères a été analysée pour deux secteurs de 150 ha chacun, sur une période de 250 ans (1732-1988). La méthode utilisée consiste en une analyse spatiale, à l'échelle du paysage, de l'évolution des friches. A une échelle plus fine (celle de la parcelle), les mécanismes biologiques influençant la dynamique de la végétation (relation plante-humus) ont été étudiés. Sur les deux secteurs, l'abandon de l'agriculture a occasionné une augmentation de l'hétéronéleité du paysage entre 1732 et 1953. Au delà de cette période, et particulièrement entre 1970 et 1988, l'hétérogénéité décroît, mais selon des degrès différents entre les deux secteurs. L'influence des fonctions écologiques (apports en eau) et des processus d'abandon de l'agriculture sont présentés. Les relations entre l'hétérogénéité du paysage et la diversité écologique et biologique sont discutées

Landscape structure indicators as a key feature in habitat selection: an operational approach to conservation planning

International audienceLandscape structure is a key factor for biodiversity conservation. We assessed the potential role of landscaperelated habitat structure on Hazel Grouse (Tetrastesbonasia) by recording the occurrence of the species. Hazel Grouse is a widely recognized endangered species, because of the habitat loss as a direct consequence of land use change that is jeopardizing the species survival. The aim of this study is to provide a method based on habitat suitability modelling to explore and analyse hazel grouse- landscape structure and its relation to key habitat features. We evaluated landscape factors and critical threshold for monitoring the species, in order to assess the predictive power of models based on field surveys, ancillary information and high resolution infrared aerial photographs. We tested Maximum Entropy (MaxEnt) algorithm, in order to predict the distribution of Hazel Grouse species, in the complex mountain landscape within the study site. This presence-only modelling method has showed numerous advantages over many other approaches. It is based on a function that links the fitness of individuals to their environment. Our results were highly consistent with field knowledge, showing that habitat modelling generated using spatial statistics and GIS can effectively help in the characterization of habitat requirements and the localization of the species suitable habitat. We found also that key drivers of Hazel Grouse distribution are not only environmental factors, in particular linked to elevation in mountain areas, but also landscape heterogeneity is a key feature. Hence, conservation of this species will require land management practices that maintain heterogeneous landscape; in particular small forest openings are essential for the species. The approach developed seem to be a promising operational tool for local and regional managers interested in species monitoring and management within the long term