排序方式: 共有121条查询结果,搜索用时 125 毫秒
81.
82.
83.
Noëlle Klein Coralie Theux Raphaël Arlettaz Alain Jacot JeanNicolas Pradervand 《Ecology and evolution》2020,10(23):13518
A growing food demand and advanced agricultural techniques increasingly affect farmland ecosystems, threatening invertebrate populations with cascading effects along the food chain upon insectivorous vertebrates. Supporting farmland biodiversity thus optimally requires the delineation of species hotspots at multiple trophic levels to prioritize conservation management. The goal of this study was to investigate the links between grassland management intensity and orthopteran density at the field scale and to upscale this information to the landscape in order to guide management action at landscape scale. More specifically, we investigated the relationships between grassland management intensity, floral indicator species, and orthopteran abundance in grasslands with different land use in the SW Swiss Alps. Field vegetation surveys of indicator plant species were used to generate a management intensity proxy, to which field assessments of orthopterans were related. Orthopteran abundance showed a hump‐shaped response to management intensity, with low values in intensified, nutrient‐rich grasslands and in nutrient‐poor, xeric grasslands, while it peaked in middle‐intensity grasslands. Combined with remote‐sensed data about grassland gross primary productivity, the above proxy was used to build landscape‐wide, spatially explicit projections of the potential distribution of orthopteran‐rich grasslands as possible foraging grounds for insectivorous vertebrates. This spatially explicit multitrophic approach enables the delineation of focal farmland areas in order to prioritize conservation action. 相似文献
84.
85.
86.
Identification of signaling components required for the prediction of cytokine release in RAW 264.7 macrophages 总被引:2,自引:0,他引:2
Background
Release of immuno-regulatory cytokines and chemokines during inflammatory response is mediated by a complex signaling network. Multiple stimuli produce different signals that generate different cytokine responses. Current knowledge does not provide a complete picture of these signaling pathways. However, using specific markers of signaling pathways, such as signaling proteins, it is possible to develop a 'coarse-grained network' map that can help understand common regulatory modules for various cytokine responses and help differentiate between the causes of their release. 相似文献87.
Gómez A Volff JN Hornung U Schartl M Wellbrock C 《Molecular biology and evolution》2004,21(2):266-275
The epidermal growth factor receptor (EGFR) gives name to a family of receptors formed by four members in mammals (EGFR, ErbB2, ErbB3, and ErbB4). Members of this family can be activated to become potent oncogenes, and many human and animal tumors express qualitatively or quantitatively altered receptors from this group. We have isolated and characterized a second egfr gene in the melanoma model fish Xiphophorus. Both Xiphophorus egfra and egfrb duplicates are co-orthologs of the mammalian egfr gene. Database analysis showed that not only egfr but also erbB3 and erbB4 are present as duplicates in some fish species. They originated from ancient duplication events that might be consistent with the hypothesis of a fish-specific genome duplication. In Xiphophorus, the egfrb gene underwent a second duplication that generated the melanoma-inducing oncogene Xmrk. The study and comparison of some of the functional characteristics of both Xiphophorus EGF receptors, including expression profile, ligand-binding abilities, and intracellular signal transduction revealed that Xiphophorus Egfra not only shares common features with Egfrb and the human EGFR but also shows significant differences in its functional characteristics. The mechanism of maintenance of these duplicates remains to be clarified. 相似文献
88.
89.
Tournier JN Quesnel-Hellmann A Mathieu J Montecucco C Tang WJ Mock M Vidal DR Goossens PL 《Journal of immunology (Baltimore, Md. : 1950)》2005,174(8):4934-4941
Bacillus anthracis secretes two critical virulence factors, lethal toxin (LT) and edema toxin (ET). In this study, we show that murine bone marrow-derived dendritic cells (DC) infected with B. anthracis strains secreting ET exhibit a very different cytokine secretion pattern than DC infected with B. anthracis strains secreting LT, both toxins, or a nontoxinogenic strain. ET produced during infection selectively inhibits the production of IL-12p70 and TNF-alpha, whereas LT targets IL-10 and TNF-alpha production. To confirm the direct role of the toxins, we show that purified ET and LT similarly disrupt cytokine secretion by DC infected with a nontoxinogenic strain. These effects can be reversed by specific inhibitors of each toxin. Furthermore, ET inhibits in vivo IL-12p70 and IFN-gamma secretion induced by LPS. These results suggest that ET produced during infection impairs DC functions and cooperates with LT to suppress the innate immune response. This may represent a new strategy developed by B. anthracis to escape the host immune response. 相似文献
90.
Simon?DevinEmail author Lo?c?Bollache Pierre-Yves?No?l Jean-Nicolas?Beisel 《Hydrobiologia》2005,551(1):137-146
Freshwater biodiversity is threatened by several mechanisms, of which the introduction of non-indigenous species and habitat
alteration are the two most important. Exotic species act at various levels of organisation of macroinvertebrate communities,
and are involved in different processes mediating their impacts on biodiversity, such as habitat modification or negative
interactions with autochthonous fauna. The present work gives a list of the 43 French freshwater non-indigenous species, which
represent 1.2% of the French freshwater macroinvertebrates. We provide their geographic origins, their distributions among
zoological units by comparison with the native fauna and their functional characteristics according to a recent typology based
on bio/ecological traits. An exponential trend of the cumulated number of non-indigenous species was evidenced, with a clumping
of invaders within crustaceans and molluscs. Donor areas of non-indigenous species are in majority European, and the Ponto-Caspian
basin is identified as the principal one. This pattern could be explained by a spread along waterways but its origin lies
in a process of recolonisation of defaunated areas following several episodes of glaciation/deglaciation in Western Europe
during the last 80,000 years. Finally, from a functional point of view, non-indigenous species exhibit a limited diversity,
with two functional groups representing 80% of them. 相似文献