A stage in female development: girls at puberty     

Unger RK 《Science (New York, N.Y.)》1984,224(4650):722

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Analgesic efficacy of an oral transmucosal spray formulation of meloxicam alone or in combination with tramadol in cats with naturally occurring osteoarthritis          下载免费PDF全文

Beatriz P Monteiro  Mary P Klinck  Maxim Moreau  Martin Guillot  Paulo VM Steagall  Daniel K Edge  Jean‐Pierre Pelletier  Johanne Martel‐Pelletier  Dominique Gauvin  Jérôme RE del Castillo  Eric Troncy 《Veterinary anaesthesia and analgesia》2016,43(6):643-651

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Expression Pattern of Apoptotic Genes in Vitrified‐Thawed Bovine Oocytes     

VM Anchamparuthy  RE Pearson  FC Gwazdauskas 《Reproduction in domestic animals》2010,45(5):e83-e90

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The influence of precipitation pulses on soil respiration - Assessing the “Birch effect” by stable carbon isotopes     

Stephan Unger  Cristina Máguas  Teresa S. David 《Soil biology & biochemistry》2010,42(10):1800-1810

Sudden pulse-like events of rapidly increasing CO₂-efflux occur in soils under seasonally dry climates in response to rewetting after drought. These occurrences, termed “Birch effect”, can have a marked influence on the ecosystem carbon balance. Current hypotheses indicate that the “Birch” pulse is caused by rapidly increased respiration and mineralization rates in response to changing moisture conditions but the underlying mechanisms are still unclear. Here, we present data from an experimental field study using straight-forward stable isotope methodology to gather new insights into the processes induced by rewetting of dried soils and evaluate current hypotheses for the “Birch“-CO₂-pulse. Two irrigation experiments were conducted on bare soil, root-free soil and intact vegetation during May and August 2005 in a semi-arid Mediterranean holm oak forest in southern Portugal. We continuously monitored CO₂-fluxes along with their isotopic compositions before, during and after the irrigation. δ¹³C signatures of the first CO₂-efflux burst, occurring immediately after rewetting, fit the hypothesis that the “Birch” pulse is caused by the rapid mineralization of either dead microbial biomass or osmoregulatory substances released by soil microorganisms in response to hypo-osmotic stress in order to avoid cell lyses. The response of soil CO₂-efflux to rewetting was smaller under mild (May) than under severe drought (August) and isotopic compositions indicated a larger contribution of anaplerotic carbon uptake with increasing soil desiccation. Both length and severity of drought periods probably play a key role for the microbial response to the rewetting of soils and thus for ecosystem carbon sequestration.  相似文献   

Der Einfluß hoher N-Gaben auf die zellulolytische Aktivität des Bodens sowie Beziehungen zwischen Mikroorganismentätigkeit und Ertragsleistung einer Weide     

Horst Unger 《Archives of Agronomy and Soil Science》2013,59(1-3):215-232

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Rapid sedimentological and biological assessment of hydrocarbon contaminated sediments     

Robert J. Diaz  Lars Johan Hansson  Rutger Rosenberg  Paul C. Gapcynski  Michael A. Unger 《Water, air, and soil pollution》1993,66(3-4):251-266

It is possible to rapidly detect the presence of high concentrations of sediment associated hydrocarbons using a sediment profile camera and simultaneously evaluate the general sedimentological and biological character of a contaminated area. In sediments that were heavily contaminated with hydrocarbons from spills and chronic long-term additions the presence of hydrocarbons was seen about 50% of the time in the sediment profile images as unique features, ‘H spots’. The presence of these features was related to the concentration of hydrocarbons in the sediment. In highly contaminated muddy sediments ‘H spots’ were found in images collected at stations that had from 270 to 610 ppt total hydrocarbons. Sedimentological and biological information obtained from the sediment profile images confirmed the impacted nature of Elizabeth River sediments. Sediment profile imaging provide a means of obtaining an overall evaluation of the quality of a habitat and impacts on that habitat from pollution related environmental disturbances. While qualitative, an advantage of sediment profile image data is that they can be evaluated in less than a day and used to quickly locate inclusions of hydrocarbons in the sediments for further quantitative chemical or biological sampling, or mapping of heavily contaminated areas.  相似文献   

Monolithic microfabricated valves and pumps by multilayer soft lithography     

Unger MA  Chou HP  Thorsen T  Scherer A  Quake SR 《Science (New York, N.Y.)》2000,288(5463):113-116

Soft lithography is an alternative to silicon-based micromachining that uses replica molding of nontraditional elastomeric materials to fabricate stamps and microfluidic channels. We describe here an extension to the soft lithography paradigm, multilayer soft lithography, with which devices consisting of multiple layers may be fabricated from soft materials. We used this technique to build active microfluidic systems containing on-off valves, switching valves, and pumps entirely out of elastomer. The softness of these materials allows the device areas to be reduced by more than two orders of magnitude compared with silicon-based devices. The other advantages of soft lithography, such as rapid prototyping, ease of fabrication, and biocompatibility, are retained.  相似文献   

Diabetic hyperglycemia: link to impaired glucose transport in pancreatic beta cells   总被引：23，自引：0，他引：23  

R H Unger 《Science (New York, N.Y.)》1991,251(4998):1200-1205

Glucose uptake into pancreatic beta cells by means of the glucose transporter GLUT-2, which has a high Michaelis constant, is essential for the normal insulin secretory response to hyperglycemia. In both autoimmune and nonautoimmune diabetes, this glucose transport is reduced as a consequence of down-regulation of the normal beta-cell transporter. In autoimmune diabetes, circulating immunoglobulins can further impair this glucose transport by inhibiting functionally intact transporters. Insights into mechanisms of the unresponsiveness of beta cells to hyperglycemia may improve the management and prevention of diabetes.  相似文献   

Evolution of supergene families associated with insecticide resistance   总被引：5，自引：0，他引：5  

Ranson H  Claudianos C  Ortelli F  Abgrall C  Hemingway J  Sharakhova MV  Unger MF  Collins FH  Feyereisen R 《Science (New York, N.Y.)》2002,298(5591):179-181

The emergence of insecticide resistance in the mosquito poses a serious threat to the efficacy of many malaria control programs. We have searched the Anopheles gambiae genome for members of the three major enzyme families- the carboxylesterases, glutathione transferases, and cytochrome P450s-that are primarily responsible for metabolic resistance to insecticides. A comparative genomic analysis with Drosophila melanogaster reveals that a considerable expansion of these supergene families has occurred in the mosquito. Low gene orthology and little chromosomal synteny paradoxically contrast the easily identified orthologous groups of genes presumably seeded by common ancestors. In A. gambiae, the independent expansion of paralogous genes is mainly a consequence of the formation of clusters among locally duplicated genes. These expansions may reflect the functional diversification of supergene families consistent with major differences in the life history and ecology of these organisms. These data provide a basis for identifying the resistance-associated enzymes within these families. This will enable the resistance status of mosquitoes, flies, and possibly other holometabolous insects to be monitored. The analyses also provide the means for identifying previously unknown molecules involved in fundamental biological processes such as development.  相似文献   

Three-dimensional structure of a recombinant gap junction membrane channel     

Unger VM  Kumar NM  Gilula NB  Yeager M 《Science (New York, N.Y.)》1999,283(5405):1176-1180

Gap junction membrane channels mediate electrical and metabolic coupling between adjacent cells. The structure of a recombinant cardiac gap junction channel was determined by electron crystallography at resolutions of 7.5 angstroms in the membrane plane and 21 angstroms in the vertical direction. The dodecameric channel was formed by the end-to-end docking of two hexamers, each of which displayed 24 rods of density in the membrane interior, which is consistent with an alpha-helical conformation for the four transmembrane domains of each connexin subunit. The transmembrane alpha-helical rods contrasted with the double-layered appearance of the extracellular domains. Although not indicative for a particular type of secondary structure, the protein density that formed the extracellular vestibule provided a tight seal to exclude the exchange of substances with the extracellular milieu.  相似文献