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A global experiment suggests climate warming will not accelerate litter decomposition in streams but might reduce carbon sequestration 总被引:2,自引:0,他引:2
Boyero L Pearson RG Gessner MO Barmuta LA Ferreira V Graça MA Dudgeon D Boulton AJ Callisto M Chauvet E Helson JE Bruder A Albariño RJ Yule CM Arunachalam M Davies JN Figueroa R Flecker AS Ramírez A Death RG Iwata T Mathooko JM Mathuriau C Gonçalves JF Moretti MS Jinggut T Lamothe S M'Erimba C Ratnarajah L Schindler MH Castela J Buria LM Cornejo A Villanueva VD West DC 《Ecology letters》2011,14(3):289-294
The decomposition of plant litter is one of the most important ecosystem processes in the biosphere and is particularly sensitive to climate warming. Aquatic ecosystems are well suited to studying warming effects on decomposition because the otherwise confounding influence of moisture is constant. By using a latitudinal temperature gradient in an unprecedented global experiment in streams, we found that climate warming will likely hasten microbial litter decomposition and produce an equivalent decline in detritivore-mediated decomposition rates. As a result, overall decomposition rates should remain unchanged. Nevertheless, the process would be profoundly altered, because the shift in importance from detritivores to microbes in warm climates would likely increase CO(2) production and decrease the generation and sequestration of recalcitrant organic particles. In view of recent estimates showing that inland waters are a significant component of the global carbon cycle, this implies consequences for global biogeochemistry and a possible positive climate feedback. 相似文献
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Frank R Murphy Razao Issa Xiaoying Zhou Shabna Ratnarajah Hideaki Nagase Michael J P Arthur Christopher Benyon John P Iredale 《The Journal of biological chemistry》2002,277(13):11069-11076
The activated hepatic stellate cell (HSC) is central to liver fibrosis as the major source of collagens I and III and the tissue inhibitors of metalloproteinase-1 (TIMP-1). During spontaneous recovery from liver fibrosis, there is a decrease of TIMP expression, an increase in collagenase activity, and increased apoptosis of HSC, highlighting a potential role for TIMP-1 in HSC survival. In this report, we use tissue culture and in vivo models to demonstrate that TIMP-1 directly inhibits HSC apoptosis. TIMP-1 demonstrated a consistent, significant, and dose-dependent antiapoptotic effect for HSC activated in tissue culture and stimulated to undergo apoptosis by serum deprivation, cycloheximide exposure, and nerve growth factor stimulation. A nonfunctional mutated TIMP-1 (T2G mutant) in which all other domains are conserved did not inhibit apoptosis, indicating that inhibition of apoptosis was mediated through MMP inhibition. Synthetic MMP inhibitors also inhibited HSC apoptosis. Studies of experimental liver cirrhosis demonstrated that persistent expression of TIMP-1 mRNA determined by PCR correlated with persistence of activated HSC quantified by alpha smooth muscle actin staining, while in fibrosis, loss of activated HSC correlated with a reduction in TIMP-1 mRNA. We conclude that TIMP-1 inhibits apoptosis of activated HSC via MMP inhibition. 相似文献
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Lavenia Ratnarajah Andrew R. Bowie Delphine Lannuzel Klaus M. Meiners Stephen Nicol 《PloS one》2014,9(12)
The availability of micronutrients is a key factor that affects primary productivity in High Nutrient Low Chlorophyll (HNLC) regions of the Southern Ocean. Nutrient supply is governed by a range of physical, chemical and biological processes, and there are significant feedbacks within the ecosystem. It has been suggested that baleen whales form a crucial part of biogeochemical cycling processes through the consumption of nutrient-rich krill and subsequent defecation, but data on their contribution are scarce. We analysed the concentration of iron, cadmium, manganese, cobalt, copper, zinc, phosphorus and carbon in baleen whale faeces and muscle, and krill tissue using inductively coupled plasma mass spectrometry. Metal concentrations in krill tissue were between 20 thousand and 4.8 million times higher than typical Southern Ocean HNLC seawater concentrations, while whale faecal matter was between 276 thousand and 10 million times higher. These findings suggest that krill act as a mechanism for concentrating and retaining elements in the surface layer, which are subsequently released back into the ocean, once eaten by whales, through defecation. Trace metal to carbon ratios were also higher in whale faeces compared to whale muscle indicating that whales are concentrating carbon and actively defecating trace elements. Consequently, recovery of the great whales may facilitate the recycling of nutrients via defecation, which may affect productivity in HNLC areas. 相似文献
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The effect of leaf toughness on the diet preference of two shredding invertebrates, Caenota plicata (Trichoptera: Calocidae) and Antipodeus wellingtoni (Amphipoda) using native leaves, Eucalyptus globulus, Eucalyptus obliqua and Pomaderris apetala, and one exotic species, Alnus glutinosa (Alder) were tested in the laboratory. We hypothesised that the softer textured leaves of P. apetala and A. glutinosa would be preferred over the tougher eucalypt leaves. Leaf toughness was measured using a penetrometer and preference was
calculated based on Chesson–Manly selection index. E. globulus, E. obliqua and A. glutinosa were all consumed to some extent; however, there was a clear avoidance of P. apetala by both shredder species. Only A. wellingtoni showed a clear preference for E. globulus. This study demonstrates that the toughness of leaves does not affect the consumption of leaves by A. wellingtoni and C. plicata. Hence there is no reason to assume a priori that the tougher Australian leaves would be avoided by local shredders as have
been observed in northern hemisphere studies. 相似文献
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Amrutha Nisthul A. Archana P. Retnakumari Shabna A. Ruby John Anto 《Journal of receptor and signal transduction research》2013,33(4):335-341
AbstractDe novo lipogenesis (DNL) by upregulation of fatty acid synthase (FASN) is an important metabolic alteration of cancer cells. FASN is over-expressed in several cancers and is often associated with a high risk of recurrence and poor prognosis. Differential expression of FASN in cancer cells and their normal counterparts leads to the impression that FASN can be an attractive druggable target in cancer therapy. Present study focuses on identification of inhibitors against FASN ketoacyl synthase (KS) domain from Asinex Biodesign compound database using in silico tools. Virtual screening resulted in the identification of two hit compounds BDD27845077 and BDD27845082 with a common core structure. Molecular Docking studies showed that BDD27845077 and BDD27845082 bind at the substrate entry channel of KS domain with GScore –12.03?kcal/mol and –12.29?kcal/mol respectively. Molecular dynamics (MD) simulation of the protein-ligand complexes shows the binding stability of ligands with FASN-KS. In vitro validation of BDD27845082 demonstrated that the compound possesses antiproliferative activity in a panel of human cancer cell lines including MDA-MB-231 (breast cancer), HCT-116 (colon cancer) and HeLa (cervical cancer) with maximum sensitivity against HCT-116 (IC 50?=?25?µM). The study put forward two lead compounds against FASN with favorable pharmacokinetic profile as indicated by virtual screening tools for the development of cancer chemotherapeutics. 相似文献
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