Letter to the Editor     

Urs Giger.  Vicki N. Meyers-Wallen.  Donald F. Patterson  Kennett Square. PA  AIvin F. Weber  Shirley D. Johnston  Lance C. Buoen.  St. Paul 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1989,3(4):245-245

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Green-light supplementation for enhanced lettuce growth under red- and blue-light-emitting diodes   总被引：9，自引：0，他引：9  

Kim HH  Goins GD  Wheeler RM  Sager JC 《HortScience : a publication of the American Society for Horticultural Science》2004,39(7):1617-1622

Plants will be an important component of future long-term space missions. Lighting systems for growing plants will need to be lightweight, reliable, and durable, and light-emitting diodes (LEDs) have these characteristics. Previous studies demonstrated that the combination of red and blue light was an effective light source for several crops. Yet the appearance of plants under red and blue lighting is purplish gray making visual assessment of any problems difficult. The addition of green light would make the plant leave appear green and normal similar to a natural setting under white light and may also offer a psychological benefit to the crew. Green supplemental lighting could also offer benefits, since green light can better penetrate the plant canopy and potentially increase plant growth by increasing photosynthesis from the leaves in the lower canopy. In this study, four light sources were tested: 1) red and blue LEDs (RB), 2) red and blue LEDs with green fluorescent lamps (RGB), 3) green fluorescent lamps (GF), and 4) cool-white fluorescent lamps (CWF), that provided 0%, 24%, 86%, and 51% of the total PPF in the green region of the spectrum, respectively. The addition of 24% green light (500 to 600 nm) to red and blue LEDs (RGB treatment) enhanced plant growth. The RGB treatment plants produced more biomass than the plants grown under the cool-white fluorescent lamps (CWF treatment), a commonly tested light source used as a broad-spectrum control.  相似文献   

Global mineralogical and aqueous mars history derived from OMEGA/Mars Express data     

Bibring JP  Langevin Y  Mustard JF  Poulet F  Arvidson R  Gendrin A  Gondet B  Mangold N  Pinet P  Forget F  Berthé M  Bibring JP  Gendrin A  Gomez C  Gondet B  Jouglet D  Poulet F  Soufflot A  Vincendon M  Combes M  Drossart P  Encrenaz T  Fouchet T  Merchiorri R  Belluci G  Altieri F  Formisano V  Capaccioni F  Cerroni P  Coradini A  Fonti S  Korablev O  Kottsov V  Ignatiev N  Moroz V  Titov D  Zasova L  Loiseau D  Mangold N  Pinet P  Douté S  Schmitt B  Sotin C  Hauber E  Hoffmann H  Jaumann R  Keller U  Arvidson R  Mustard JF  Duxbury T 《Science (New York, N.Y.)》2006,312(5772):400-404

Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the "phyllocian" era) are found in the oldest terrains; sulfates were formed in a second era (the "theiikian" era) in an acidic environment. Beginning about 3.5 billion years ago, the last era (the "siderikian") is dominated by the formation of anhydrous ferric oxides in a slow superficial weathering, without liquid water playing a major role across the planet.  相似文献   

The effect of oxygen on biochemical networks and the evolution of complex life     

Raymond J  Segrè D 《Science (New York, N.Y.)》2006,311(5768):1764-1767

The evolution of oxygenic photosynthesis and ensuing oxygenation of Earth's atmosphere represent a major transition in the history of life. Although many organisms retreated to anoxic environments, others evolved to use oxygen as a high-potential redox couple while concomitantly mitigating its toxicity. To understand the changes in biochemistry and enzymology that accompanied adaptation to O2, we integrated network analysis with information on enzyme evolution to infer how oxygen availability changed the architecture of metabolic networks. Our analysis revealed the existence of four discrete groups of networks of increasing complexity, with transitions between groups being contingent on the presence of key metabolites, including molecular oxygen, which was required for transition into the largest networks.  相似文献   

Moving toward a more physiological model: application of mucin to refine the in vitro digestion/Caco-2 cell culture system     

Jin F  Welch R  Glahn R 《Journal of agricultural and food chemistry》2006,54(23):8962-8967

The objective of this study was to determine if a combination of commercially available mucin and an 8 microm microporous membrane insert can be used to replace the 15 kDa molecular weight cutoff (MWCO) dialysis membrane used in an established in vitro digestion/Caco-2 cell culture system. Although the current model with the 15 kDa membrane correlates well with human studies, use of mucin may improve the system as the mucus layer is suspected to play a physiological role in Fe absorption. Use of mucin may also enable more complete assessment of iron bioavailability from large molecular weight forms of Fe such as heme and ferritin Fe. A range of foods or Fe (i.e., FeCl(3) +/- ascorbic acid, cooked beef, red bean, white bean, soybean, horse spleen ferritin and plant-type ferritin) were subjected to in vitro digestion. In the presence of mucin, significantly more Fe was taken up from the heme Fe (86%) and ferritin (91%) samples and significantly less Fe was taken up from the white bean samples ( approximately 70%) relative to the 15 kDa membrane. The results indicated that the forms of iron interact with mucin. The mucus layer has a significant effect on Fe uptake. Further refinement and characterization of the mucin method is needed before it can be deemed to be a suitable replacement for the dialysis membrane.  相似文献   

Effect of bread baking on the bioavailability of hydrogen-reduced iron powder added to unenriched refined wheat flour     

Maekawa AA  Glahn RP  Lei XG  Miller DD 《Journal of agricultural and food chemistry》2006,54(21):8362-8368

Elemental iron powders are widely used to fortify flour and other cereal products. Our objective was to test the hypothesis that baking enhances the bioavailability of elemental iron powders by oxidizing Fe(0) to Fe(2+) or Fe(3+). An in vitro digestion/Caco-2 cell culture model and a piglet model were used to measure bioavailability. Bread flour, either unfortified or fortified with hydrogen-reduced (HR) iron powder or FeSO(4) (300 mg Fe/kg flour), was baked into bread. For the in vitro studies, bread samples were treated with pepsin at pH 2, 3, 4, 5, 6, or 7 and subsequently incubated with pancreatic enzymes at pH 7 in a chamber positioned above monolayers of cultured Caco-2 cells. Ferritin formation in the cells was used as an index of iron bioavailability. Ferritin formation in cells fed HR Fe bread was similar to cells fed FeSO(4) bread when the peptic digestion was conducted at a pH 2 but lower when the peptic phase was conducted at pH 3, 4, 5, 6, or 7 (P < 0.05). Pig diets containing 35% dried bread were prepared and fed to cross-bred (Hampshire x Landrace x Yorkshire) anemic pigs in two studies. The rate of increase in hemoglobin Fe over the feeding period was used to calculate relative biological value (RBV), an index of iron bioavailability. In the first pig study, RBV of HR Fe added to flour prior to baking was 47.9% when compared to FeSO(4) fortified flour (P < 0.05). In the second pig study, a third treatment consisting of unfortified bread with HR iron added during diet mixing (after bread baking) was included. RBVs of the HR Fe diet (Fe added after baking) and HR Fe diet (Fe added before baking) were 40.1% and 53.5%, respectively, compared to the FeSO(4) diet. Differences in RBV between the HR Fe (before and after baking) and FeSO(4) (before baking) treatment groups were significant, but the difference between the before and after HR treatment groups was not significant. We conclude that bread baking does not enhance the bioavailability of elemental iron powders.  相似文献   

Immunology. Sugar determines antibody activity     

Burton DR  Dwek RA 《Science (New York, N.Y.)》2006,313(5787):627-628

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Climate change. Threats to water supplies in the tropical Andes     

Bradley RS  Vuille M  Diaz HF  Vergara W 《Science (New York, N.Y.)》2006,312(5781):1755-1756

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Accuracy of an oscillometric blood pressure monitor during phenylephrine-induced hypertension in dogs     

McMurphy RM  Stoll MR  McCubrey R 《American journal of veterinary research》2006,67(9):1541-1545

OBJECTIVE: To examine the agreement between direct arterial blood pressure measurements obtained from 2 arteries and indirect blood pressure measurements obtained with an oscillometric blood pressure monitor (OBPM) during normotension and phenylephrine-induced hypertension in dogs. ANIMALS: 16 male Beagles. PROCEDURES: In anesthetized dogs, arterial catheters were placed in the lingual and dorsal pedal arteries for measurement of arterial blood pressure. A blood pressure cuff was placed on either the dog's fore- or hind limb and connected to an OBPM. Systolic, diastolic, and mean arterial blood pressures (SAP, DAP, and MAP, respectively) were recorded from both arteries and the OBPM every 5 minutes for 30 minutes (baseline), during a 30-minute period in which dogs received a phenylephrine infusion IV to induce hypertension, and for 30 minutes after discontinuation of the infusion. Mean differences in blood pressure values and confidence intervals were calculated to compare the indirect and direct measurement techniques. RESULTS: In dogs, oscillometry underestimated SAP during normotension, and the difference between oscillometric and direct measurements increased during hypertension. Oscillometry underestimated DAP, but the difference between oscillometric and direct measurements decreased during hypertension. There was close agreement among techniques for MAP determinations. Biases between direct measurements and OPBM blood pressure values measured from dogs' forelimbs or hind limbs were not significantly different. CONCLUSIONS AND CLINICAL RELEVANCE: In normotensive dogs, oscillometric measurements of MAP and SAP agreed more closely with direct arterial pressure measurements than oscillometric estimates of DAP. Oscillometric measurement of MAP was accurate during both normotension and hypertension in dogs.  相似文献   

Crystal structure of a lipid G protein-coupled receptor     

Hanson MA  Roth CB  Jo E  Griffith MT  Scott FL  Reinhart G  Desale H  Clemons B  Cahalan SM  Schuerer SC  Sanna MG  Han GW  Kuhn P  Rosen H  Stevens RC 《Science (New York, N.Y.)》2012,335(6070):851-855

The lyso-phospholipid sphingosine 1-phosphate modulates lymphocyte trafficking, endothelial development and integrity, heart rate, and vascular tone and maturation by activating G protein-coupled sphingosine 1-phosphate receptors. Here, we present the crystal structure of the sphingosine 1-phosphate receptor 1 fused to T4-lysozyme (S1P(1)-T4L) in complex with an antagonist sphingolipid mimic. Extracellular access to the binding pocket is occluded by the amino terminus and extracellular loops of the receptor. Access is gained by ligands entering laterally between helices I and VII within the transmembrane region of the receptor. This structure, along with mutagenesis, agonist structure-activity relationship data, and modeling, provides a detailed view of the molecular recognition and requirement for hydrophobic volume that activates S1P(1), resulting in the modulation of immune and stromal cell responses.  相似文献