Ecology. Silk moth deaths show perils of biocontrol     

Jensen MN 《Science (New York, N.Y.)》2000,290(5500):2230-2231

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Mechanism of Na+/H+ antiporting     

Arkin IT  Xu H  Jensen MØ  Arbely E  Bennett ER  Bowers KJ  Chow E  Dror RO  Eastwood MP  Flitman-Tene R  Gregersen BA  Klepeis JL  Kolossváry I  Shan Y  Shaw DE 《Science (New York, N.Y.)》2007,317(5839):799-803

Na+/H+ antiporters are central to cellular salt and pH homeostasis. The structure of Escherichia coli NhaA was recently determined, but its mechanisms of transport and pH regulation remain elusive. We performed molecular dynamics simulations of NhaA that, with existing experimental data, enabled us to propose an atomically detailed model of antiporter function. Three conserved aspartates are key to our proposed mechanism: Asp164 (D164) is the Na+-binding site, D163 controls the alternating accessibility of this binding site to the cytoplasm or periplasm, and D133 is crucial for pH regulation. Consistent with experimental stoichiometry, two protons are required to transport a single Na+ ion: D163 protonates to reveal the Na+-binding site to the periplasm, and subsequent protonation of D164 releases Na+. Additional mutagenesis experiments further validated the model.  相似文献   

Intellectual property. Enhanced: intellectual property landscape of the human genome     

Jensen K  Murray F 《Science (New York, N.Y.)》2005,310(5746):239-240

The impact of gene patents on downstream research and innovation are unknown, in part because of a lack of empirical data on the extent and nature of gene patenting. In this Policy Forum, the authors show that 20% of human gene DNA sequences are patented and that some genes are patented as many as 20 times. Unsurprisingly, genes associated with health and disease are more patented than the genome at large. The intellectual property rights for some genes can become highly fragmented between many owners, which suggests that downstream innovators may face considerable costs to gain access to gene-oriented technologies.  相似文献   

Patterns of mental ability and socioeconomic status     

Jensen AR 《Science (New York, N.Y.)》1968,160(3826):439

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Another phocine distemper outbreak in Europe     

Jensen T  van de Bildt M  Dietz HH  Andersen TH  Hammer AS  Kuiken T  Osterhaus A 《Science (New York, N.Y.)》2002,297(5579):209

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Depletion of Vitamin A Reserves in the Livers of Cattle     

Frey PR  Jensen R 《Science (New York, N.Y.)》1947,105(2725):313-314

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Dynamic complex formation during the yeast cell cycle     

de Lichtenberg U  Jensen LJ  Brunak S  Bork P 《Science (New York, N.Y.)》2005,307(5710):724-727

To analyze the dynamics of protein complexes during the yeast cell cycle, we integrated data on protein interactions and gene expression. The resulting time-dependent interaction network places both periodically and constitutively expressed proteins in a temporal cell cycle context, thereby revealing previously unknown components and modules. We discovered that most complexes consist of both periodically and constitutively expressed subunits, which suggests that the former control complex activity by a mechanism of just-in-time assembly. Consistent with this, we show that additional regulation through targeted degradation and phosphorylation by Cdc28p (Cdk1) specifically affects the periodically expressed proteins.  相似文献   

Accumulation of trehalose in the thermophilic fungus Chaetomium thermophilum var. coprophilum in response to heat or salt stress     

Helene Friborg Jepsen  Bo Jensen 《Soil biology & biochemistry》2004,36(10):1669-1674

The disaccharide trehalose, known to be an effective protectant against various kinds of stress, was observed to accumulate in the cytosol of Chaetomium thermophilum var. coprophilum during heat stress. Trehalose was apparently neither involved in the defence of C. thermophilum var. coprophilum against high concentrations of sodium chloride nor directly linked to thermophily.In C. thermophilum var. coprophilum three different trehalose hydrolyzing activities were eluted from a mono Q anion exchange column by sodium chloride concentrations of 0.10, 0.15 and 0.24 M, respectively.  相似文献   

Comments to ‘A N tracing model to analyse N transformations in old grassland soil’     

Jesper Luxhøi  Lars S. Jensen 《Soil biology & biochemistry》2005,37(5):1003-1005

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Modeling vertical movement of organic matter in a soil incubated for 41 years with C labeled straw     

Sander Bruun  Bent T. Christensen  Erik S. Jensen 《Soil biology & biochemistry》2007,39(1):368-371

The distribution of organic matter (OM) in the soil profile reflects the balance between inputs and decomposition at different depths as well as transport of OM within the profile. In this study we modeled movement of OM in the soil profile as a result of mechanisms resulting in dispersive and advective movement. The model was used to interpret the distribution of ¹⁴C in the soil profile 41 years after the labeling event. The model fitted the observed distribution of ¹⁴C well (R²=0.988, AIC_c=−82.6), with a dispersion constant of D=0.71 cm² yr⁻¹ and an advection constant of v=0.0081 cm yr⁻¹. However, the model consistently underestimated the amount of OM in the soil layers from 27 to 37 cm depth. A possible explanation for this is that different fractions of OM are transported by different mechanisms. For example, particulate OM, organomineral colloids and dissolved OM are not likely to be transported by the same mechanisms. A model with two OM fractions, one moving exclusively by dispersive processes (D=0.26 cm² yr⁻¹) and another moving by both dispersive (D=0.99 cm² yr⁻¹) and advective (v=0.23 cm yr⁻¹) processes provided a slightly better fit to the data (R²=0.995, AIC_c=−83.6). More importantly, however, this model did not show the consistent underestimation from 27 to 37 cm soil depth. This corroborates the assumption that differing movement mechanisms for different OM fractions are responsible for the observed distribution of ¹⁴C in the profile. However, varying dispersion, advection, and decay of OM with depth are also possible explanations.  相似文献