Dentate gyrus NMDA receptors mediate rapid pattern separation in the hippocampal network     

McHugh TJ  Jones MW  Quinn JJ  Balthasar N  Coppari R  Elmquist JK  Lowell BB  Fanselow MS  Wilson MA  Tonegawa S 《Science (New York, N.Y.)》2007,317(5834):94-99

Forming distinct representations of multiple contexts, places, and episodes is a crucial function of the hippocampus. The dentate gyrus subregion has been suggested to fulfill this role. We have tested this hypothesis by generating and analyzing a mouse strain that lacks the gene encoding the essential subunit of the N-methyl-d-aspartate (NMDA) receptor NR1, specifically in dentate gyrus granule cells. The mutant mice performed normally in contextual fear conditioning, but were impaired in the ability to distinguish two similar contexts. A significant reduction in the context-specific modulation of firing rate was observed in the CA3 pyramidal cells when the mutant mice were transferred from one context to another. These results provide evidence that NMDA receptors in the granule cells of the dentate gyrus play a crucial role in the process of pattern separation.  相似文献   

Lunar Gravity via Apollo 14 Doppler Radio Tracking     

Sjogren WL  Gottlieb P  Muller PM  Wollenhaupt W 《Science (New York, N.Y.)》1972,175(4018):165-168

Gravity measurements at high resolution were obtained over a 100-kilometer band from + 70 degrees to -70 degrees of longitude during the orbits of low periapsis altitude (approximately 16 kilometers). The line-of-sight accelerations are plotted on Aeronautical Chart and Information Center mercator charts (scale 1 : 1,000,000) as contours at 10-milligal intervals. Direct correlations between gravity variations and surface features are easily determined. Theophilus, Hipparchus, and Ptolemaeus are negative features, whereas Mare Nectaris is a large positive region. The acceleration profiles over Mare Nectaris are suggestive of a broad disk near the surface rather than a deeply buried spherical body. These data are in good agreement with the short arc of Apollo 12 lunar module descent data.  相似文献   

Role of Erythronium americanum Ker. in Energy Flow and Nutrient Dynamics of a Northern Hardwood Forest Ecosystem     

Muller RN  Bormann FH 《Science (New York, N.Y.)》1976,193(4258):1126-1128

The aboveground activity of the spring herb, Erythronium americanum, is restricted to the period between snowmelt and forest canopy development. Its phenology and production capacity closely adapt the species to this temporal niche in northern deciduous forests. While E. americanum has a minor effect on energy flow, it may reduce losses of potassium and nitrogen from the ecosystem during the period of maximum removal by incorporating these elements in accumulating biomass. Later, during the summer, these nutrients are made available when the above-ground, nonperennating tissues decay.  相似文献   

Classic to postclassic in highland central Mexico     

Dumond DE  Muller F 《Science (New York, N.Y.)》1972,175(4027):1208-1215

The data and argument we have presented converge on three points. 1) With the decline and abandonment of Teotihuacan by the end of the Metepec phase (Teotihuacan IV), the valleys of Mexico and of Puebla-Tlax-cala witnessed the development of a ceramic culture that was represented, on the one hand, by obvious Teotihuacan derivations in presumably ritual ware and possible Teotihuacan derivations in simpler pottery of red-on-buff, and, on the other hand, by elements that seem to represent a resurgence of Preclassic characteristics. Whether the development is explained through a measure of outside influence or as a local phenomenon, the direct derivation of a substantial portion of the complex from Classic Teotihuacan is unmistakable. This transitional horizon predated the arrival of plumbate tradeware in highland central Mexico. 2) The transitional horizon coincided with (and no doubt was an integral part of) an alteration of Classic settlement patterns so drastic that it must bespeak political disruption. Nevertheless, there is no evidence that the Postclassic center of Tula represented a significant force in the highlands at that time. There is no evidence that the center of Cholula, which may even have been substantially abandoned during the previous period, was able to exert any force at this juncture; it appears more likely that Cholula was largely reoccupied after the abandonment of Teotihuacan. There is no direct evidence of domination by Xochicalco or any other known major foreign center, although some ceramic traits suggest that relatively minor influences may have emanated from Xochicalco; unfortunately, the state of research at that center does not permit a determination at this time. Thus the most reasonable view on the basis of present evidence is that the abandonment of Teotihuacan was not the direct result of the strength of another centralized power, although some outside populations may have been involved in a minor way. Whatever the proximate cause, however, it is now clear that the abandonment of Teotihuacan led to a period of Balkanization in which no single center, or pair of centers, were dominant in the highlands. 3) The transitional horizon saw the immediate development of a cultural distinction between the Valley of Mexico and the Valley of Puebla-Tlaxcala, a distinction in which differential degrees of outside cultural influence may have played a part. This distinction was magnified in the early Postclassic, with the rising power of Tula on the west and of Cholula on the east, and Balkanization ended with the growth of empire.  相似文献   

Biomarkers of caloric restriction may predict longevity in humans     

Roth GS  Lane MA  Ingram DK  Mattison JA  Elahi D  Tobin JD  Muller D  Metter EJ 《Science (New York, N.Y.)》2002,297(5582):811

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Intersubband electroluminescence from silicon-based quantum cascade structures     

Dehlinger G  Diehl L  Gennser U  Sigg H  Faist J  Ensslin K  Grutzmacher D  Muller E 《Science (New York, N.Y.)》2000,290(5500):2277-2280

The quantum cascade laser, which uses electronic transitions within a single band of a semiconductor, constitutes a possible way to integrate active optical components into silicon-based technology. This concept necessitates a transition with a narrow linewidth and an upper state with a sufficiently long lifetime. We report the observation of intersubband electroluminescence from a p-type silicon/silicon-germanium quantum cascade structure, centered at 130 millielectron volts with a width of 22 millielectron volts, with the expected polarization, and discernible up to 180 kelvin. The nonradiative lifetime is found to depend strongly on the design of the quantum well structure, and is shown to reach values comparable to that of an equivalent GaInAs/AlInAs laser structure.  相似文献   

Social-ethical issues concerning the control strategy of animal diseases in the European Union: A survey   总被引：1，自引：0，他引：1  

Nina E. Cohen  Marcel A.P.M. van  Asseldonk  Elsbeth N. Stassen 《Agriculture and Human Values》2007,24(4):499-510

In 2004 a survey was conducted in the member states of the European Union designed to gain greater insight into the views on control strategies for foot and mouth disease, classical swine fever, and avian influenza with respect to the epidemiological, economic and social-ethical consequences of each of these animal diseases. This article presents the results of the social-ethical survey. A selection of stakeholders from each member state was asked to prioritize issues for the prevention and control of these diseases. A majority of stakeholders chose preventive measures as the preferred issue. An analysis was done to determine whether there were differences in views expressed by stakeholders from member states with a history of recent epidemics and ones without such a history, and whether there were regional differences. There were no differences between member states with or without a history of recent epidemics. There were indeed regional differences between the priority orders from Northern and Southern Europe on the one hand, and from Eastern Europe on the other. Nina E. Cohen is a biologist and is a researcher at the Wageningen University. She is specialized in societal and ethical issues in human–animal relationships. Her current research is focused on the social-ethical issues concerning the prevention and control of foot and mouth disease, classical swine fever and avian influenza. Marcel A.P.M. van Asseldonk has studied animal science. Currently he works at the Institute for Risk Management in Agriculture (IRMA) of the Wageningen University. He is specialized in the design and pricing of insurance policies and animal health funds for the main livestock epidemics. Elsbeth N. Stassen is a veterinarian and professor of Animals and Society at the Wageningen University. Elsbeth Stassen is specialized in animal health, animal welfare and human–animal relationships. She was a member of a governmental welfare committee during the avian influenza epidemic in the Netherlands in 2003.  相似文献   

Biohybrid artificial pancreas: long-term implantation studies in diabetic, pancreatectomized dogs   总被引：5，自引：0，他引：5  

S J Sullivan  T Maki  K M Borland  M D Mahoney  B A Solomon  T E Muller  A P Monaco  W L Chick 《Science (New York, N.Y.)》1991,252(5006):718-721

Diabetic complications such as neuropathy, retinopathy, and renal and cardiovascular disease continue to pose major health risks for diabetic patients. Consequently, much effort has focused on approaches that could replace conventional insulin therapy and provide more precise regulation of blood glucose levels. The biohybrid perfused artificial pancreas was designed to incorporate islet tissue and a selectively permeable membrane that isolates this tissue from the immune system of the recipient. Biohybrid pancreas devices containing canine islet allografts were implanted in ten pancreatectomized dogs requiring 18 to 32 units of injected insulin daily. These implants resulted in good control of fasting glucose levels in six of these animals without further exogenous insulin for periods of up to 5 months.  相似文献   

ONE-MAN AUTHORITY CITATIONS     

Muller CH 《Science (New York, N.Y.)》1939,90(2331):207-208

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Mass spectrometry of intact V-type ATPases reveals bound lipids and the effects of nucleotide binding     

Zhou M  Morgner N  Barrera NP  Politis A  Isaacson SC  Matak-Vinković D  Murata T  Bernal RA  Stock D  Robinson CV 《Science (New York, N.Y.)》2011,334(6054):380-385

The ability of electrospray to propel large viruses into a mass spectrometer is established and is rationalized by analogy to the atmospheric transmission of the common cold. Much less clear is the fate of membrane-embedded molecular machines in the gas phase. Here we show that rotary adenosine triphosphatases (ATPases)/synthases from Thermus thermophilus and Enterococcus hirae can be maintained intact with membrane and soluble subunit interactions preserved in vacuum. Mass spectra reveal subunit stoichiometries and the identity of tightly bound lipids within the membrane rotors. Moreover, subcomplexes formed in solution and gas phases reveal the regulatory effects of nucleotide binding on both ATP hydrolysis and proton translocation. Consequently, we can link specific lipid and nucleotide binding with distinct regulatory roles.  相似文献