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81.
Boulter L Govaere O Bird TG Radulescu S Ramachandran P Pellicoro A Ridgway RA Seo SS Spee B Van Rooijen N Sansom OJ Iredale JP Lowell S Roskams T Forbes SJ 《Nature medicine》2012,18(4):572-579
During chronic injury a population of bipotent hepatic progenitor cells (HPCs) become activated to regenerate both cholangiocytes and hepatocytes. Here we show in human diseased liver and mouse models of the ductular reaction that Notch and Wnt signaling direct specification of HPCs via their interactions with activated myofibroblasts or macrophages. In particular, we found that during biliary regeneration, expression of Jagged 1 (a Notch ligand) by myofibroblasts promoted Notch signaling in HPCs and thus their biliary specification to cholangiocytes. Alternatively, during hepatocyte regeneration, macrophage engulfment of hepatocyte debris induced Wnt3a expression. This resulted in canonical Wnt signaling in nearby HPCs, thus maintaining expression of Numb (a cell fate determinant) within these cells and the promotion of their specification to hepatocytes. By these two pathways adult parenchymal regeneration during chronic liver injury is promoted. 相似文献
82.
Caio Cesar de Souza Alves Adam Collison Luke Hatchwell Maximilian Plank Matthew Morten Paul S. Foster Sebastian L. Johnston Cristiane Fran?a da Costa Mauro Vieira de Almeida Henrique Couto Teixeira Ana Paula Ferreira Joerg Mattes 《PloS one》2013,8(11)
Background
Severe asthma is associated with T helper (TH) 2 and 17 cell activation, airway neutrophilia and phosphoinositide-3-kinase (PI3K) activation. Asthma exacerbations are commonly caused by rhinovirus (RV) and also associated with PI3K-driven inflammation. Anthraquinone derivatives have been shown to reduce PI3K-mediated AKT phosphorylation in-vitro.Objective
To determine the anti-inflammatory potential of anthraquinones in-vivo.Methods
BALB/c mice were sensitized and challenged with crude house dust mite extract to induce allergic airways disease and treated with mitoxantrone and a novel non-cytotoxic anthraquinone derivative. Allergic mice were also infected with RV1B to induce an exacerbation.Results
Anthraquinone treatment reduced AKT phosphorylation, hypoxia-inducible factor-1α and vascular endothelial growth factor expression, and ameliorated allergen- and RV-induced airways hyprereactivity, neutrophilic and eosinophilic inflammation, cytokine/chemokine expression, mucus hypersecretion, and expression of TH2 proteins in the airways. Anthraquinones also boosted type 1 interferon responses and limited RV replication in the lung.Conclusion
Non-cytotoxic anthraquinone derivatives may be of therapeutic benefit for the treatment of severe and RV-induced asthma by blocking pro-inflammatory pathways regulated by PI3K/AKT. 相似文献83.
Paerl HW Dyble J Twomey L Pinckney JL Nelson J Kerkhof L 《Antonie van Leeuwenhoek》2002,81(1-4):487-507
The impacts of growing coastal pollution and habitat alteration accompanying human encroachment are of great concern at the
microbial level, where much of the ocean's primary production and biogeochemical cycling takes place. Coastal ecosystems are
also under the influence of natural perturbations such as major storms and flooding. Distinguishing the impacts of natural
and human stressors is essential for understanding environmentally-induced change in microbial diversity and function. The
objective of this paper is to discuss the applications and merits of recently developed molecular, ecophysiological and analytical
indicators and their utility in examining anthropogenic and climatic impacts on the structure and function of coastal microbial
communities. The nitrogen-limited Neuse River Estuary and Pamlico Sound, North Carolina are used as examples of ecosystems
experiencing both anthropogenic (i.e., accelerating eutrophication) and climatic stress (increasing frequencies of tropical
storms and hurricanes). Additional examples are derived from a coastal monitoring site (LEO) on the Atlantic coast of New
Jersey and Galveston Bay, on the Gulf of Mexico. In order to assess structure, function, and trophic state of these and other
coastal ecosystems, molecular (DNA and RNA-based) characterizations of the microbial taxa involved in carbon, nitrogen and
other nutrient transformations can be combined with diagnostic pigment-based indicators of primary producer groups. Application
of these methods can reveal process-level microbial community responses to environmental variability over a range of scales.
Experimental approaches combined with strategic monitoring utilizing these methods will facilitate: (a) understanding organismal
and community responses to environmental change, and (b) synthesizing these responses in the context of ecosystem models that
integrate physical, chemical and biotic variability with environmental controls.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
84.
Summary A baiting technique was developed to estimate the population ofDrechslera nodulosa (Berk. and Curt.) Subram. and Jain in soil by using susceptible ragi (Eleusine coracana Gaertn.) culms. The number of lesions developed on baited culms were reduced with the reduction in concentration ofD. nodulosa propagules in both sterilized and unsterilized soils. Based on this a standard correlation (concentrationvs infection probability) was established which was found to be quite efficient method to estimate the population in soil and to bait even when the inoculum level was 4 propagules per g of soil. 相似文献
85.
Tsutomu Akama Yong-Kang Zhang Yvonne R. Freund Pamela Berry Joanne Lee Eric E. Easom Robert T. Jacobs Jacob J. Plattner Michael J. Witty Rosemary Peter Tim G. Rowan Kirsten Gillingwater Reto Brun Bakela Nare Luke Mercer Musheng Xu Jiangong Wang Hao Liang 《Bioorganic & medicinal chemistry letters》2018,28(1):6-10
Novel l-valinate amide benzoxaboroles and analogues were designed and synthesized for a structure-activity-relationship (SAR) investigation to optimize the growth inhibitory activity against Trypanosoma congolense (T. congolense) and Trypanosoma vivax (T. vivax) parasites. The study identified 4-fluorobenzyl (1-hydroxy-7-methyl-1,3-dihydrobenzo[c][1,2]oxaborole-6-carbonyl)-l-valinate (5, AN11736), which showed IC50 values of 0.15?nM against T. congolense and 1.3?nM against T. vivax, and demonstrated 100% efficacy with a single dose of 10?mg/kg against both T. congolense and T. vivax in mouse models of infection (IP dosing) and in the target animal, cattle, dosed intramuscularly. AN11736 has been advanced to early development studies. 相似文献
86.
Soft‐Bodied Fossils Are Not Simply Rotten Carcasses – Toward a Holistic Understanding of Exceptional Fossil Preservation 下载免费PDF全文
Luke A. Parry Fiann Smithwick Klara K. Nordén Evan T. Saitta Jesus Lozano‐Fernandez Alastair R. Tanner Jean‐Bernard Caron Gregory D. Edgecombe Derek E. G. Briggs Jakob Vinther 《BioEssays : news and reviews in molecular, cellular and developmental biology》2018,40(1)
Exceptionally preserved fossils are the product of complex interplays of biological and geological processes including burial, autolysis and microbial decay, authigenic mineralization, diagenesis, metamorphism, and finally weathering and exhumation. Determining which tissues are preserved and how biases affect their preservation pathways is important for interpreting fossils in phylogenetic, ecological, and evolutionary frameworks. Although laboratory decay experiments reveal important aspects of fossilization, applying the results directly to the interpretation of exceptionally preserved fossils may overlook the impact of other key processes that remove or preserve morphological information. Investigations of fossils preserving non‐biomineralized tissues suggest that certain structures that are decay resistant (e.g., the notochord) are rarely preserved (even where carbonaceous components survive), and decay‐prone structures (e.g., nervous systems) can fossilize, albeit rarely. As we review here, decay resistance is an imperfect indicator of fossilization potential, and a suite of biological and geological processes account for the features preserved in exceptional fossils. 相似文献
87.
Simplifying understory complexity in oil palm plantations is associated with a reduction in the density of a cleptoparasitic spider,Argyrodes miniaceus (Araneae: Theridiidae), in host (Araneae: Nephilinae) webs 下载免费PDF全文
Dakota M. Spear William A. Foster Andreas Dwi Advento Mohammad Naim Jean‐Pierre Caliman Sarah H. Luke Jake L. Snaddon Sudharto Ps Edgar C. Turner 《Ecology and evolution》2018,8(3):1595-1603
Expansion of oil palm agriculture is currently one of the main drivers of habitat modification in Southeast Asia. Habitat modification can have significant effects on biodiversity, ecosystem function, and interactions between species by altering species abundances or the available resources in an ecosystem. Increasing complexity within modified habitats has the potential to maintain biodiversity and preserve species interactions. We investigated trophic interactions between Argyrodes miniaceus, a cleptoparasitic spider, and its Nephila spp. spider hosts in mature oil palm plantations in Sumatra, Indonesia. A. miniaceus co‐occupy the webs of Nephila spp. females and survive by stealing prey items caught in the web. We examined the effects of experimentally manipulated understory vegetation complexity on the density and abundance of A. miniaceus in Nephila spp. webs. Experimental understory treatments included enhanced complexity, standard complexity, and reduced complexity understory vegetation, which had been established as part of the ongoing Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Project. A. miniaceus density ranged from 14.4 to 31.4 spiders per square meter of web, with significantly lower densities found in reduced vegetation complexity treatments compared with both enhanced and standard treatment plots. A. miniaceus abundance per plot was also significantly lower in reduced complexity than in standard and enhanced complexity plots. Synthesis and applications: Maintenance of understory vegetation complexity contributes to the preservation of spider host–cleptoparasite relationships in oil palm plantations. Understory structural complexity in these simplified agroecosystems therefore helps to support abundant spider populations, a functionally important taxon in agricultural landscapes. In addition, management for more structurally complex agricultural habitats can support more complex trophic interactions in tropical agroecosystems. 相似文献
88.
89.
90.
Microbiota niches have space and/or nutrient restrictions, which has led to the coevolution of cooperation, specialisation, and competition within the population. Different animal and environmental niches contain defined resident microbiota that tend to be stable over time and offer protection against undesired intruders. Yet fluxes can occur, which alter the composition of a bacterial population. In humans, the microbiota are now considered a key contributor to maintenance of health and homeostasis, and its alteration leads to dysbiosis. The bacterial type VI secretion system (T6SS) transports proteins into the environment, directly into host cells or can function as an antibacterial weapon by killing surrounding competitors. Upon contact with neighbouring cells, the T6SS fires, delivering a payload of effector proteins. In the absence of an immunity protein, this results in growth inhibition or death of prey leading to a competitive advantage for the attacker. It is becoming apparent that the T6SS has a role in modulating and shaping the microbiota at multiple levels, which is the focus of this review. Discussed here is the T6SS, its role in competition, key examples of its effect upon the microbiota, and future avenues of research. 相似文献