Time Course of Far-Red Inactivation of Photomorphogenesis     

Klein WH  Withrow RB  Withrow AP  Elstad V 《Science (New York, N.Y.)》1957,125(3258):1146-1147

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Role of brain insulin receptor in control of body weight and reproduction     

Brüning JC  Gautam D  Burks DJ  Gillette J  Schubert M  Orban PC  Klein R  Krone W  Müller-Wieland D  Kahn CR 《Science (New York, N.Y.)》2000,289(5487):2122-2125

Insulin receptors (IRs) and insulin signaling proteins are widely distributed throughout the central nervous system (CNS). To study the physiological role of insulin signaling in the brain, we created mice with a neuron-specific disruption of the IR gene (NIRKO mice). Inactivation of the IR had no impact on brain development or neuronal survival. However, female NIRKO mice showed increased food intake, and both male and female mice developed diet-sensitive obesity with increases in body fat and plasma leptin levels, mild insulin resistance, elevated plasma insulin levels, and hypertriglyceridemia. NIRKO mice also exhibited impaired spermatogenesis and ovarian follicle maturation because of hypothalamic dysregulation of luteinizing hormone. Thus, IR signaling in the CNS plays an important role in regulation of energy disposal, fuel metabolism, and reproduction.  相似文献   

Radiation theory between 1896 and 1925: the tiger and the shark     

Klein MJ 《Science (New York, N.Y.)》1984,224(4646):277

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Microbiology. Turning up the heat on Histoplasma capsulatum     

Klein BS 《Science (New York, N.Y.)》2000,290(5495):1311-1312

Many fungal pathogens are opportunistic, that is, they infect individuals who have a compromised immune system. Histoplasma capsulatum is a common pathogenic fungus that lives happily inside the phagosomes of macrophages. As Klein explains in his Perspective, an important H. capsulatum virulence factor, CBP1, has been found, which mops up free calcium ions within the phagosome, enabling the yeast to live under calcium-poor conditions (Sebhgati et al.). Chelating calcium ions may also have the added benefit that when the phagosome fuses with the lysosome, destructive lysosomal enzymes that require calcium ions for activity remain inactive.  相似文献   

Contributions of two types of calcium channels to synaptic transmission and plasticity   总被引：7，自引：0，他引：7  

B Edmonds  M Klein  N Dale  E R Kandel 《Science (New York, N.Y.)》1990,250(4984):1142-1147

In Aplysia sensory and motor neurons in culture, the contributions of the major classes of calcium current can be selectively examined while transmitter release and its modulation are examined. A slowly inactivating, dihydropyridine-sensitive calcium current does not contribute either to normal synaptic transmission or to any of three different forms of plasticity: presynaptic inhibition, homosynaptic depression, and presynaptic facilitation. This current does contribute, however, to a fourth form of plasticity--modulation of transmitter release by tonic depolarization of the sensory neuron. By contrast, a second calcium current, which is rapidly inactivating and dihydropyridine-insensitive, contributes to release elicited by the transient depolarization of an action potential and to the other three forms of plasticity.  相似文献   

A novel mechanism of somatic rearrangement predicted by a human T-cell antigen receptor beta-chain complementary DNA   总被引：10，自引：0，他引：10  

A D Duby  K A Klein  C Murre  J G Seidman 《Science (New York, N.Y.)》1985,228(4704):1204-1206

The T-cell antigen receptor is a cell surface molecule vital in mediating the cellular immune response. The arrangement and rearrangement of the gene segments encoding the beta-chain polypeptide of the receptor are similar to those of immunoglobulin gene segments. The two constant region genes of the human T-cell antigen receptor are 8 kilobases apart with a cluster of joining segments located 5' of each constant region gene. Although most beta-chain gene rearrangements involve the variable, diversity, and joining segments, analysis of a beta-chain complementary DNA clone suggests the occasional occurrence of another type of rearrangement.  相似文献   

Sampling and characterization of air for organic compounds     

W. W. Bunn  E. R. Deane  D. W. Klein  R. D. Kleopfer 《Water, air, and soil pollution》1975,4(3-4):367-380

Computerized gas chromatography/mass spectrometry was applied to the analysis of organic compounds in air at a National Air Surveillance Network station in Kansas City. Sampling approaches used included particulate sampling, adsorption on XAD-2 resin followed by solvent elution, and adsorption on Tenax GC followed by direct desorption onto a gas chromatography column. Eighty-two compounds were identified. Unusually large amounts of phenol and phenolformaldehyde resin intermediates were found.  相似文献   

Does transport of water to roots limit water uptake of field crops?     

Henning Kage  Wilfried Ehlers 《植物养料与土壤学杂志》1996,159(6):583-590

The question was examined under which conditions the water extraction rate of plant roots in the field can be limited by water transport to the roots. For this purpose we used a numerical solution of the single root model. Scenario calculations were carried out in order to investigate the general model behaviour. A sensitivity analysis showed that initial volumetric water content and root length density are of greater importance than root diameter in determining the maximum water transport rate to the roots. Data from a field experiment were taken, describing root length density, volumetric water content and water uptake rates under oats (Avena saliva L.) and faba beans (Vicia faba L.) as model input parameters. With this data the model calculated the water content difference between the bulk soil and the root surface which is necessary to induce a water flow to the roots matching the observed water uptake rate. Root length densities below the grain legume crop faba beans are one order of magnitude lower compared to that of the cereal crop oats. The therefore higher specific water influx rates of faba beans roots resulted in a higher decrease in water content near the root surface. However, water uptake by faba beans was controlled by the water flow towards the roots probably only in deeper soil layers with very low root length density. For the given conditions no transport limitation of water uptake was calculated, when rooting densities were higher than about 0.1 cm.cm^?3.  相似文献   

Comment on “Effects of agricultural machinery with high-axle load on soil properties of normally managed fields” (Authors L. Schäfer-Landefeld, R. Brandhuber, S. Fenner, H.-J. Koch, N. Stockfisch. Soil Till. Res. 75 (2004) 75–86)     

Wilfried Ehlers  Michael J. Goss  Rainer Horn 《Soil & Tillage Research》2005,80(1-2):251-254

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Measurement of hearing in dogs by respiration audiometry     

L J Bradford  J H McKinley  C L Rousey  D E Klein 《American journal of veterinary research》1973,34(9):1183-1187

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