CX3CR1-mediated dendritic cell access to the intestinal lumen and bacterial clearance   总被引：3，自引：0，他引：3  

Niess JH  Brand S  Gu X  Landsman L  Jung S  McCormick BA  Vyas JM  Boes M  Ploegh HL  Fox JG  Littman DR  Reinecker HC 《Science (New York, N.Y.)》2005,307(5707):254-258

Dendritic cells (DCs) and macrophages are critical to innate and adaptive immunity to the intestinal bacterial microbiota. Here, we identify a myeloid-derived mucosal DC in mice, which populates the entire lamina propria of the small intestine. Lamina propria DCs were found to depend on the chemokine receptor CX3CR1 to form transepithelial dendrites, which enable the cells to directly sample luminal antigens. CX3CR1 was also found to control the clearance of entero-invasive pathogens by DCs. Thus, CX3CR1-dependent processes, which control host interactions of specialized DCs with commensal and pathogenic bacteria, may regulate immunological tolerance and inflammation.  相似文献   

5-HT4(a) receptors avert opioid-induced breathing depression without loss of analgesia     

Manzke T  Guenther U  Ponimaskin EG  Haller M  Dutschmann M  Schwarzacher S  Richter DW 《Science (New York, N.Y.)》2003,301(5630):226-229

Opiates are widely used analgesics in anesthesiology, but they have serious adverse effects such as depression of breathing. This is caused by direct inhibition of rhythm-generating respiratory neurons in the Pre-Boetzinger complex (PBC) of the brainstem. We report that serotonin 4(a) [5-HT4(a)] receptors are strongly expressed in respiratory PBC neurons and that their selective activation protects spontaneous respiratory activity. Treatment of rats with a 5-HT4 receptor-specific agonist overcame fentanyl-induced respiratory depression and reestablished stable respiratory rhythm without loss of fentanyl's analgesic effect. These findings imply the prospect of a fine-tuned recovery from opioid-induced respiratory depression, through adjustment of intracellular adenosine 3',5'-monophosphate levels through the convergent signaling pathways in neurons.  相似文献   

A predator unmasked: life cycle of Bdellovibrio bacteriovorus from a genomic perspective     

Rendulic S  Jagtap P  Rosinus A  Eppinger M  Baar C  Lanz C  Keller H  Lambert C  Evans KJ  Goesmann A  Meyer F  Sockett RE  Schuster SC 《Science (New York, N.Y.)》2004,303(5658):689-692

Predatory bacteria remain molecularly enigmatic, despite their presence in many microbial communities. Here we report the complete genome of Bdellovibrio bacteriovorus HD100, a predatory Gram-negative bacterium that invades and consumes other Gram-negative bacteria. Its surprisingly large genome shows no evidence of recent gene transfer from its prey. A plethora of paralogous gene families coding for enzymes, such as hydrolases and transporters, are used throughout the life cycle of B. bacteriovorus for prey entry, prey killing, and the uptake of complex molecules.  相似文献   

The chemistry of sexual deception in an orchid-wasp pollination system     

Schiestl FP  Peakall R  Mant JG  Ibarra F  Schulz C  Franke S  Francke W 《Science (New York, N.Y.)》2003,302(5644):437-438

The "sexually deceptive" orchid Chiloglottis trapeziformis attracts males of its pollinator species, the thynnine wasp Neozeleboria cryptoides, by emitting a unique volatile compound, 2-ethyl-5-propylcyclohexan-1,3-dione, which is also produced by female wasps as a male-attracting sex pheromone.  相似文献   

Carbon flux and growth in mature deciduous forest trees exposed to elevated CO2   总被引：1，自引：0，他引：1  

Körner C  Asshoff R  Bignucolo O  Hättenschwiler S  Keel SG  Peláez-Riedl S  Pepin S  Siegwolf RT  Zotz G 《Science (New York, N.Y.)》2005,309(5739):1360-1362

Whether rising atmospheric carbon dioxide (CO2) concentrations will cause forests to grow faster and store more carbon is an open question. Using free air CO2 release in combination with a canopy crane, we found an immediate and sustained enhancement of carbon flux through 35-meter-tall temperate forest trees when exposed to elevated CO2. However, there was no overall stimulation in stem growth and leaf litter production after 4 years. Photosynthetic capacity was not reduced, leaf chemistry changes were minor, and tree species differed in their responses. Although growing vigorously, these trees did not accrete more biomass carbon in stems in response to elevated CO2, thus challenging projections of growth responses derived from tests with smaller trees.  相似文献   

Infrared echoes near the supernova remnant Cassiopeia A     

Krause O  Rieke GH  Birkmann SM  Le Floc'h E  Gordon KD  Egami E  Bieging J  Hughes JP  Young ET  Hinz JL  Quanz SP  Hines DC 《Science (New York, N.Y.)》2005,308(5728):1604-1606

Two images of Cassiopeia A obtained at 24 micrometers with the Spitzer Space Telescope over a 1-year time interval show moving structures outside the shell of the supernova remnant to a distance of more than 20 arc minutes. Individual features exhibit apparent motions of 10 to 20 arc seconds per year, independently confirmed by near-infrared observations. The observed tangential velocities are at roughly the speed of light. It is likely that the moving structures are infrared echoes, in which interstellar dust is heated by the explosion and by flares from the compact object near the center of the remnant.  相似文献   

Economics. Can integration tame conflicts?     

Goette L  Meier S 《Science (New York, N.Y.)》2011,334(6061):1356-1357

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Science policy. Changing incentives to publish     

Franzoni C  Scellato G  Stephan P 《Science (New York, N.Y.)》2011,333(6043):702-703

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Phylogeny of the SARS coronavirus     

Eickmann M  Becker S  Klenk HD  Doerr HW  Stadler K  Censini S  Guidotti S  Masignani V  Scarselli M  Mora M  Donati C  Han JH  Song HC  Abrignani S  Covacci A  Rappuoli R 《Science (New York, N.Y.)》2003,302(5650):1504-1505

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Degradability of black carbon and its impact on trace gas fluxes and carbon turnover in paddy soils   总被引：2，自引：0，他引：2  

Christian Knoblauch  Arina-Ann Maarifat  Stephan M. Haefele 《Soil biology & biochemistry》2011,43(9):1768-1778

Rice paddy soils are characterized by anoxic conditions, anaerobic carbon turnover, and significant emissions of the greenhouse gas methane. A main source for soil organic matter in paddy fields is the rice crop residue that is returned to fields if not burned. We investigated as an alternative treatment the amendment of rice paddies with rice residues that have been charred to black carbon. This treatment might avoid various negative side effects of traditional rice residue treatments. Although charred biomass is seen as almost recalcitrant, its impact on trace gas (CO₂, CH₄) production and emissions in paddy fields has not been studied. We quantified the degradation of black carbon produced from rice husks in four wetland soils in laboratory incubations. In two of the studied soils the addition of carbonised rice husks resulted in a transient increase in carbon mineralisation rates in comparison to control soils without organic matter addition. After almost three years, between 4.4% and 8.5% of the black carbon added was mineralised to CO₂ under aerobic and anaerobic conditions, respectively. The addition of untreated rice husks resulted in a strong increase in carbon mineralisation rates and in the same time period 77%-100% of the added rice husks were mineralised aerobically and 31%-54% anaerobically. The ¹³C-signatures of respired CO₂ gave a direct indication of black carbon mineralisation to CO_2. In field trials we quantified the impact of rice husk black carbon or untreated rice husks on soil respiration and methane emissions. The application of black carbon had no significant effect on soil respiration but significantly enhanced methane emissions in the first rice crop season. The additional methane released accounted for only 0.14% of black carbon added. If the same amount of organic carbon was added as untreated rice husks, 34% of the applied carbon was released as CO₂ and methane in the first season. Furthermore, the addition of fresh harvest residues to paddy fields resulted in a disproportionally high increase in methane emissions. Estimating the carbon budget of the different rice crop residue treatments indicated that charring of rice residues and adding the obtained black carbon to paddy fields instead of incorporating untreated harvest residues may reduce field methane emissions by as much as 80%. Hence, the production of black carbon from rice harvest residues could be a powerful strategy for mitigating greenhouse gas emissions from rice fields.  相似文献