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排序方式: 共有892条查询结果,搜索用时 31 毫秒
1.
Maxime Lenormand Guillaume Papuga Olivier Argagnon Maxence Soubeyrand Guilhem De Barros Samuel Alleaume Sandra Luque 《Ecology and evolution》2019,9(1):237-250
The delimitation of bioregions helps to understand historical and ecological drivers of species distribution. In this work, we performed a network analysis of the spatial distribution patterns of plants in south of France (Languedoc‐Roussillon and Provence‐Alpes‐Côte d'Azur) to analyze the biogeographical structure of the French Mediterranean flora at different scales. We used a network approach to identify and characterize biogeographical regions, based on a large database containing 2.5 million of geolocalized plant records corresponding to more than 3,500 plant species. This methodology is performed following five steps, from the biogeographical bipartite network construction to the identification of biogeographical regions under the form of spatial network communities, the analysis of their interactions, and the identification of clusters of plant species based on the species contribution to the biogeographical regions. First, we identified two sub‐networks that distinguish Mediterranean and temperate biota. Then, we separated eight statistically significant bioregions that present a complex spatial structure. Some of them are spatially well delimited and match with particular geological entities. On the other hand, fuzzy transitions arise between adjacent bioregions that share a common geological setting, but are spread along a climatic gradient. The proposed network approach illustrates the biogeographical structure of the flora in southern France and provides precise insights into the relationships between bioregions. This approach sheds light on ecological drivers shaping the distribution of Mediterranean biota: The interplay between a climatic gradient and geological substrate shapes biodiversity patterns. Finally, this work exemplifies why fragmented distributions are common in the Mediterranean region, isolating groups of species that share a similar eco‐evolutionary history. 相似文献
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Three different fluorochrome and specific counterstain combination (DAPI/AMD, DA/DAPI and CMA/DA) treatments were applied to the chromosomes of four Microtidae (Rodentia) species. The results complete the data obtained in our previous paper (Burgos, M., Jiménez, R., & Dìaz de la Guardia, R., Genome 30:540–546, 1988) and prove that the changes in the constitutive heterochromatin in the evolution of the karyotypes of these species are not only due to gain or loss of heterochromatin, but are qualitative with respect to their nucleotide composition, repeated base pair organization or DNA-protein complex modification. These variations lead to the differential response to the fluorescence dye combinations used. 相似文献
4.
Nina Bertaux-Skeirik Rui Feng Michael A. Schumacher Jing Li Maxime M. Mahe Amy C. Engevik Jose E. Javier Richard M. Peek Jr Karen Ottemann Veronique Orian-Rousseau Gregory P. Boivin Michael A. Helmrath Yana Zavros 《PLoS pathogens》2015,11(2)
The cytotoxin-associated gene (Cag) pathogenicity island is a strain-specific
constituent of Helicobacter pylori (H. pylori) that
augments cancer risk. CagA translocates into the cytoplasm where it stimulates cell
signaling through the interaction with tyrosine kinase c-Met receptor, leading
cellular proliferation. Identified as a potential gastric stem cell marker,
cluster-of-differentiation (CD) CD44 also acts as a co-receptor for c-Met, but
whether it plays a functional role in H. pylori-induced epithelial
proliferation is unknown. We tested the hypothesis that CD44 plays a functional role
in H. pylori-induced epithelial cell proliferation. To assay changes
in gastric epithelial cell proliferation in relation to the direct interaction with
H. pylori, human- and mouse-derived gastric organoids were
infected with the G27 H. pylori strain or a mutant G27 strain
bearing cagA deletion (∆CagA::cat). Epithelial proliferation
was quantified by EdU immunostaining. Phosphorylation of c-Met was analyzed by
immunoprecipitation followed by Western blot analysis for expression of CD44 and
CagA. H. pylori infection of both mouse- and human-derived gastric
organoids induced epithelial proliferation that correlated with c-Met
phosphorylation. CagA and CD44 co-immunoprecipitated with phosphorylated c-Met. The
formation of this complex did not occur in organoids infected with
∆CagA::cat. Epithelial proliferation in response to
H. pylori infection was lost in infected organoids derived from
CD44-deficient mouse stomachs. Human-derived fundic gastric organoids exhibited an
induction in proliferation when infected with H. pylorithat was not
seen in organoids pre-treated with a peptide inhibitor specific to CD44. In the
well-established Mongolian gerbil model of gastric cancer, animals treated with CD44
peptide inhibitor Pep1, resulted in the inhibition of H.
pylori-induced proliferation and associated atrophic gastritis. The current
study reports a unique approach to study H. pylori interaction with
the human gastric epithelium. Here, we show that CD44 plays a functional role in
H. pylori-induced epithelial cell proliferation. 相似文献
5.
Maxime Eeraerts 《Journal of Applied Entomology》2020,144(8):751-754
Mason bees (Osmia spp.) are receiving increasing attention as they are very effective pollinators of multiple crops. However, different bee-associated kleptoparasites are known which can be detrimental to the development of the bees’ offspring. To date, clear evidence-based guidelines to control these kleptoparasites are lacking for growers. This study investigates whether different types of artificial nesting materials—cardboard tubes and wooden grooved boards—influence the development of the European orchard bee (Osmia cornuta) as well as the infestation rate of kleptoparasitic mites in the bees’ nest. This preliminary study provides insight that cardboard tubes reduce the infestation rate of mites by 81.8% and as such promote successful development of the European orchard bee by 15.5%. Using cardboard tubes over wooden grooved boards should be advised to growers as an effective management strategy to avoid infestation of kleptoparasitic mites and to enhance successful bee development. 相似文献
6.
Maxime Bruto Claire Prigent-Combaret Patricia Luis Yvan Mo?nne-Loccoz Daniel Muller 《Proceedings. Biological sciences / The Royal Society》2014,281(1789)
Even genetically distant prokaryotes can exchange genes between them, and these horizontal gene transfer events play a central role in adaptation and evolution. While this was long thought to be restricted to prokaryotes, certain eukaryotes have acquired genes of bacterial origin. However, gene acquisitions in eukaryotes are thought to be much less important in magnitude than in prokaryotes. Here, we describe the complex evolutionary history of a bacterial catabolic gene that has been transferred repeatedly from different bacterial phyla to stramenopiles and fungi. Indeed, phylogenomic analysis pointed to multiple acquisitions of the gene in these filamentous eukaryotes—as many as 15 different events for 65 microeukaryotes. Furthermore, once transferred, this gene acquired introns and was found expressed in mRNA databases for most recipients. Our results show that effective inter-domain transfers and subsequent adaptation of a prokaryotic gene in eukaryotic cells can happen at an unprecedented magnitude. 相似文献
7.
Camille V. Chagneau Clmence Massip Nadge Bossuet-Greif Christophe Fremez Jean-Paul Motta Ayaka Shima Cline Besson Pauline Le Faouder Nicolas Cnac Marie-Paule Roth Hlne Coppin Maxime Fontani Patricia Martin Jean-Philippe Nougayrde Eric Oswald 《PLoS pathogens》2021,17(2)
Urinary tract infections (UTIs) are among the most common outpatient infections, with a lifetime incidence of around 60% in women. We analysed urine samples from 223 patients with community-acquired UTIs and report the presence of the cleavage product released during the synthesis of colibactin, a bacterial genotoxin, in 55 of the samples examined. Uropathogenic Escherichia coli strains isolated from these patients, as well as the archetypal E. coli strain UTI89, were found to produce colibactin. In a murine model of UTI, the machinery producing colibactin was expressed during the early hours of the infection, when intracellular bacterial communities form. We observed extensive DNA damage both in umbrella and bladder progenitor cells. To the best of our knowledge this is the first report of colibactin production in UTIs in humans and its genotoxicity in bladder cells. 相似文献
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PrPC is associated with a variety of functions, and its ability to interact with a multitude of partners, including itself, may largely explain PrP multifunctionality and the lack of consensus on the genuine physiological function of the protein in vivo. In contrast, there is a consensus in the literature that alterations in PrPC trafficking and intracellular retention result in neuronal degeneration. In addition, a proteolytic modification in the late secretory pathway termed the α-cleavage induces the secretion of PrPN1, a PrPC-derived metabolite with fascinating neuroprotective activity against toxic oligomeric Aβ molecules implicated in Alzheimer disease. Thus, studies focusing on understanding the regulation of PrPC trafficking to the cell surface and the modulation of α-cleavage are essential. The objective of this commentary is to highlight recent evidences that PrPC homodimerization stimulates trafficking of the protein to the cell surface and results in high levels of PrPN1 secretion. We also discuss a hypothetical model for these results and comment on future challenges and opportunities. 相似文献