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  • 1
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    Calcified tissue international 10 (1972), S. 82-90 
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Precipitation ; Kinetics ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La cinétique de la formation et de la transformation des précipités de phosphate de calcium, obtenus en mélangeant de volumes égaux de solutions à 6×10−3 M de calcium total et/ou phosphate total est étudiée à 25°C. Les solutions de phosphate sont préajustées à un pH de 7.4. Les changements de pH et de turbidité des solutions sont suivis simultanément en fonction du temps. Les précipités sont isolés à des intervalles de temps variables et caractérisés par diverses méthodes physico-chimiques. Initialement un précipité avec un rapport molaire Ca/P de 1.5, amorphe aux rayons X et en diffraction électronique, est formé. Le spectre IR indique la présence de PO 4 3− et de HPO 4 2− . Après une période métastable, on observe la précipitation d'un matériel cristallin dans ou sur la phase amorphe. Vingt quatre heures après préparation de l'échantillon les précipités présentent surtout les caractères du phosphate octocalcique.
    Abstract: Zusammenfassung Die Kinetik der Bildung und Transformation von Calciumphosphat-Niederschlägen wurde bei 25°C untersucht. Es wurden dazu gleiche Volumen von Lösungen gemischt, bei einer Konzentration von 6×10−3M totales Calcium und/oder totales Phosphat. Die Phosphatlösungen wurden zuerst auf pH 7,4 eingestellt. Veränderungen des pH und Trübung der Lösungen wurden gleichzeitig als eine Funktion der Zeit aufgezeichnet. Niederschläge wurden in verschiedenen Zeitintervallen isoliert und mit verschiedenen physiko-chemischen Methoden charakterisiert. Am Anfang wurde ein Niederschlag mit einem molaren Ca/P-Verhältnis von 1,5, im Röntgenbild und in der Elektronendiffraktion amorph, gebildet. Infrarotspektren deuteten die Anwesenheit von PO 4 3− - und HPO 4 2− -Ionen an. Nach einer metastabilen Periode erfolgte ein Niederschlag aus kristallinem Material innerhalb oder auf der amorphen Substanz. 24 Std nach der Herstellung der Proben zeigten die Niederschläge in der Hauptsache die Charakteristiken von Octocalciumphosphat.
    Notes: Abstract The kinetics of the formation and transformation of calcium phosphate precipitates obtained by mixing equal volumes of solutions, 6×10−3 M in total calcium and/or total phosphate was investigated at 25°. The phosphate solutions were preadjusted to pH 7.4. Changes of the pH and turbidity of the solutions were followed simultaneously as a function of time. Precipitates were isolated at various time intervals and characterized by different physicochemical methods. Initially a precipitate with a molar Ca/P ratio of 1.5, amorphous to X-ray and electron diffraction was formed. IR spectra indicated the presence of PO 4 3− and HPO 4 2− ions. After a period of metastability, precipitation of a crystalline material within or upon the amorphous matter occurred. Twenty four hours after sample preparation the precipitates showed mainly the characteristics of octacalcium phosphate.
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  • 2
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    Calcified tissue international 16 (1974), S. 145-152 
    ISSN: 1432-0827
    Keywords: EHDP ; Bone ; Chemistry ; Serum ; Rabbits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) on bone and serum chemistry were investigated in adult rabbits. EHDP was administered by subcutaneous injection at doses of 0.25, 2.5 and 10 mg/kg body weight/day for of 28 days. Blood samples were obtained weekly from each rabbit and serum levels of total calcium, ionized calcium, inorganic phosphate and alkaline phosphatase were determined. At the end of the treatment period all rabbits were sacrificed and the tibiae removed for chemical analysis and histological evaluation. The effect of EHDP administration on serum chemistry was both dose- and time-related. The highest of the three doses, 10 mg/kg/day, resulted in a time-related decrease in total serum calcium. This dose also caused a rapid but transient reduction in serum ionized calcium. The effect of EHDP on serum inorganic phosphate was biphasic. Administration of 2.5 mg/kg/day resulted in a time-related elevation in this parameter, whereas the 10 mg/kg/day dose resulted in a time-related hypophosphatemic response. There were no significant drug-related changes in tibial fat-free dry weight, ash weight, total calcium or total phosphorus values. However, administration of 2.5 and 10 mg/kg/day EHDP resulted in increased osteoid tissue as measured histologically. These results are compared with data from other EHDP studies, and discussed in relation to the maturity and growth-state of the experimental animals.
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  • 3
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    Calcified tissue international 23 (1977), S. 13-17 
    ISSN: 1432-0827
    Keywords: Dental calculus ; Glycopeptide ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A method is described for the isolation and purification of a sulphated glycopeptide from human supragingival calculus. The compound was isolated after using EDTA treatment, 2 M CaCl2 extraction, proteolytic digestion, ethanol precipitation, and finally purified by DEAE cellulose chromatography. It migrated as a single component on cellulose acetate electrophoresis, and chemical and infrared spectral analysis showed the presence of covalently attached sulphate groups. The sulphated glycopeptide was distinguished from being a sulphated glycosaminoglycan.
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  • 4
    ISSN: 1432-0975
    Keywords: Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry.
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  • 5
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    Journal of molecular evolution 15 (1980), S. 79-101 
    ISSN: 1432-1432
    Keywords: Molecules ; Interstellar ; Chemistry ; Isotopes ; Solar system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The study of interstellar molecules broadly includes two areas of interest. One area uses the unique ability of molecules to act as probes of the physical conditions in the cold, dense, visually opaque component of the interstellar medium. The physical properties of this and other components of the interstellar medium are summarized. The other area deals with the chemistry of interstellar molecules, recent aspects of which are emphasized in this review. Gas-phase chemistry, shock chemistry, and grain surface chemistry are discussed in the context of recent observations. No present observations suggest that surface reactions are relevant, but neither can they be ruled out. Ion-molecule reactions are clearly operative, at least for the simpler species. Chemical isotope fractionation is reviewed, andd it is concluded that the complexities of the chemistry allow no cosmological conclusions to be drawn from observations of deuterium in interstellar molecules, while the presence of13C in interstellar molecules permits an estimate of the12C/13C ratio which is consistent with the current concepts of the nucleosynthesis history of the Galaxy. Possible connections between interstellar molecules and the early molecular history of the solar system are discussed.
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  • 6
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    Pure and applied geophysics 118 (1980), S. 128-151 
    ISSN: 1420-9136
    Keywords: Galactic cosmic rays ; Solar proton events ; Particle precipitation ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O3 is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O3 is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O3. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°≲Λ≲70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O3 depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.
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  • 7
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    Aquatic sciences 51 (1989), S. 108-128 
    ISSN: 1420-9055
    Keywords: Chemistry ; mountain lakes ; silica ; acidity ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Alpine lakes in siliceous catchments of Tyrol and Carinthia (Austria) show signs of acidification. About 9% of the studied lakes have no alkalinity, more than 20% are below pH 6. About two thirds of all lakes have acid neutralizing capacities below 100 μeq 1−1. In spite of moderate precipitation acidity, some lakes show considerable concentrations of dissolved reactive aluminum during or shortly after snowmelt. High altitude lakes of the Alps are definitely more acidic than high mountain lakes in remote areas. Large differences in water and soil chemistry of nearby situated lakes were attributed to heterogeneities of bedrock geology. Paleolimnological investigations on former pH values of five lakes, based on diatom assemblages in the sediment, showed different developments: recent and past acidification, stable conditions, and alkalinization.
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  • 8
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    Accreditation and quality assurance 5 (2000), S. 409-413 
    ISSN: 1432-0517
    Keywords: Key words Metrology ; Comparisons ; Chemistry ; Standards
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  After stressing the importance in the modern world of accurate and reproducible measurements, the actions taken by the Bureau International des Poids et Mesures to set up, together with the regional metrology organizations, a series of key comparisons are described. They are the technical foundation of a mutual recognition of national measurement standards arrangement prepared in conjunction with the National Metrology Institutes (NMIs). This arrangement also includes the recognition of calibration and measurement certificates issued by these institutes. Then, the consequences of this arrangement for trade are described. The case of chemical analysis is illustrated by the application of the Kyoto protocol on the reduction of greenhouse gases. But the global workload to be taken up by the International Committee of Weights and Measures, its Consultative Committee for Amount of Substance and the NMIs is huge.
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  • 9
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    Calcified tissue international 14 (1974), S. 3-14 
    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Mineral ; Phase ; Chemistry ; Synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des diagrammes de phase d'équilibre ont été déterminés pour le système CaO-P2O5-H2O en utilisant des techniques de synthèse hydrothermique au cours de variatio nsde température allant de 300–600° et 2 Kb H2O de pression. De l'hydroxyapatite bien cristallisé a été synthétisé et caractérisé. De faibles variations de paramètres de la maille cristalline, liées à la température de synthèse et composition globale du matériel initial, ont été déterminées. Des conditions chimiques précises sont nécessaires pour obtenir de l'apatite, en tant que seule phase solide en équilibre dans la solution. Les résultats de diagramme de phase d'équilibre sont comparés avec ceux obtenus dans des milieux synthétiques.
    Abstract: Zusammenfassung Es wurden Gleichgewichts-Phasendiagramme für das System CaO-P2O5-H2O bestimmt, indem hydrothermale Synthese-Techniken im Temperaturbereich von 300–600° und bei einem Druck von 2 Kb H2O verwendet wurden. Es wurde gut-kristallisiertes Hydroxyapatit erzeugt und charakterisiert. Es wurden geringe Unterschiede in den Parametern der Zelleinheiten festgestellt, welche von der angewandten Temperatur und der Zusammensetzung des Startmaterials abhingen. Es waren genaue chemische Bedingungen nötig, um Apatit als die einzige feste Phase im Gleichgewicht mit der Lösung zu erhalten. Die Resultate der Gleichgewichts-Phasendiagramme werden mit früheren Untersuchungen mit der Synthesetechnik verglichen.
    Notes: Abstract Equilibrium phase diagrams have been determined for the system CaO-P2O5-H2 using hydrothermal synthesis techniques in the temperature range 300–600° and 2 Kb H2O pressure. Well-crystallized hydroxyapatite has been produced and characterized. Small variations in unit cell parameters dependent on temperature of synthesis and bulk composition of the starting materials have been determined. Precise chemical conditions were required to obtain apatite as the only solid phase in equilibrium with solution. Equilibrium phase diagram results are compared with previous synthetic investigations.
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  • 10
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    Calcified tissue international 7 (1971), S. 150-162 
    ISSN: 1432-0827
    Keywords: Uranium ; Bone ; Distribution ; Fission ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une concentration moyenne de 2.4×10−8 g U/g de cendre a été obtenue à partir de l'os humain normal. La microdistribution de l'uranium dans l'os indique que cet élément est surtout limité à surface de l'endoste et, en particulier, aux surfaces de l'os lamellaire et aux parois des canaux de Havers, ouverts dans l'os corticol. Cette répartition suggère que l'uranium se présente sous une forme chimique impropre à son incorporation dans l'apatite osseux: il ne semble donc pas exister une distribution diffuse significative de l'uranium dans l'os.
    Abstract: Zusammenfassung Eine mittlere Konzentration von 2,4×10−8 g Uran/g Asche wurde in normalen menschlichen Knochen gefunden. Die Feinverteilung von Uran im Knochen zeigt, daß dieses Element hauptsächlich an der endostalen Oberfläche vorkommt, insbesondere an der Oberfläche des trabeculären Knochens und an den Wänden der offenen Haversschen Kanäle im kortikalen Knochen. Diese Verteilung läßt vermuten, daß Uran in einer chemischen Form vorliegt, welche sich für den Einbau in das Knochenapatit nicht eignet. Daraus folgt, daß keine signifikante diffuse Verteilung des Urans innerhalb des Knochens vorliegt.
    Notes: Abstract A mean concentration of 2.4×10−8 g U/g ash has been obtained for normal human bone The microdistribution of uranium in bone indicates that this element is mainly restricted to endosteal surfaces; in particular the surfaces of trabecular bone and the walls of open Haversian canals in cortical bone. This distribution suggests that uranium is present in a chemical form that is not acceptable for incorporation into bone apatite and consequently there does not appear to be a significant diffuse distribution of uranium throughout bone.
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  • 11
    ISSN: 1432-0827
    Keywords: Morphology ; Glycosaminoglycans ; Cartilage ; Chemistry ; Audioradiography ; Healing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une perte de substance ostéo-cartilagineuse, de taille limitée et identique, est réalisée chez le lapin adulte et la cicatrisation est étudiée histologiquement et par autoradiographie après marquagein vitro au35S-sulfate. Une analyse microchimique est pratiquée pour le contenu et la composition en glycosaminoglycanes. 1. Entre la première semaine et la 4ème et 8ème semaine, un tissu conjonctif non-métachromatique se différencie en un cartilage métachromatique et la quantité de sulfate de chondroitine augmente de façon significative aux dépens des glycoprotéines. 2. Jusqu'à la 4ème semaine, la perte de substance est surtout comblée par de l'os néoformé: après cette période, la région est comblée au delà de la limite de la surface articulaire. 3. Le cartilage hyalin, ressemblant morphologiquement, autoradiographiquement et chimiquement au cartilage articulaire, en ce qui concerne la distribution en glycosaminoglycanes, constitute la surface articulaire de la perte de substance comblée dans un tiers des cas après 8 semaines. Le cartilage hyalin s'observe surtout dans les régions où de l'os néoformé a comblé la cavité médullaire. 4. Dans les deux tiers des cas, après 8 semaines, les surfaces articulaires des zones comblées comportent, non seulement du cartilage, mais aussi du tissu fibreux se formant essentiellement sur les parties latérales et dans les régions, où la cavité médullaire, fliant face, à la surface articulaire, n'a pas été comblée par du tissue osseux. La fraction glycoprotéique augmente par rapport à la fraction chondroitine sulfate. 5. Dans la majorité des cas, après 20 semaines, le cartilage néoformé subit des phénomènes dégénératifs, qui se traduisent par une diminution en chondroitine sulfate.
    Abstract: Zusammenfassung Bei ausgewachsenen Kaninchen wurde ein begrenzter, standardisierter, osteochondraler Defekt hervorgerufen, und das regenerierte Gewebe wurde histologisch und autoradiographisch durch Markierung in vitro mit35S-Sulfat und durch mikrochemische Bestimmung des Gehaltes und der Zusammensetzung der Glykosaminglykane untersucht. Die wichtigsten Befunde waren: 1. Zwischen 1 und 4–8 Wochen veränderte sich nichtmetachromatisches Bindegewebe zu metachromatisch gefärbtem Knorpel, und der Anteil an Chondroitin-Sulfat nahm auf Kosten der Glykoproteine signifikant zu. 2. Bis zu 4 Wochen war der Hauptteil des defekten Gebietes mit neugebildetem Knochen gefüllt; nach dieser Zeit lag dieser Bezirk oberhalb der Verknöcherungsgrenze in Richtung der Gelenkoberfläche. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 4. Nach 8 Wochen bestanden Teile der Gelenkoberfläche des Defektes in zwei Dritteln der Fälle nicht nur aus Knorpel, sondern auch aus fibrösem Gewebe, welches vor allem in den seitlichen Teilen des Defektes und an Stellen vorlag, wo die Markhöhle gegenüber der Gelenkoberfläche nicht mit Knochengewebe verschlossen worden war. Die Glykoproteinfraktion nahm im Vergleich zur Chondroitin-Sulfatfraktion zu. 5. Nach 20 Wochen zeigten sich in den meisten Fällen bei neugebildetem Knorpel degenerative Veränderungen, welche durch eine gewisse Abnahme des Chondroitin-Sulfats wiedergegeben wurden.
    Notes: Abstract A limited, standardized osteochondral defect was created in adult rabbits and the regenerated tissue was examined histologically and autoradiographically after labellingin vitro with35S-sulphate, and microchemically for its content and composition of glycosaminoglycans. The principal findings were: 1. Between 1 week and 4 to 8 weeks, non-metachromatic connective tissue differentiated to metachromatically stained cartilage, and the proportion of the chondroitin sulphate increased significantly at the expense of the glycoproteins. 2. Up to 4 weeks, the major part of the defect area was filled with newly formed bone; after this time, the area lay above the level of the “tidemark”, towards the articular surface. 3. Hyaline cartilage with morphological, autoradiographic and chemical resemblance to the articular cartilage in terms of the distribution of glycosaminoglycans constituted the articular surface of the defect area in one-third of the cases at observation times after 8 weeks. Hyaline cartilage was observed mainly in areas where newly formed bone had closed the medullary cavity. 4. In two-thirds of the cases, after 8 weeks, parts of the articular surface of the defect consisted not only of cartilage but also of fibrous tissue, occurring mainly in the lateral parts of the defect and in areas where the medullary cavity facing the articular surface had not been sealed by bone tissue. The glycoprotein fraction increased relative to the chondroitin sulphate fraction. 5. In most cases after 20 weeks, newly-formed cartilage underwent degenerative changes, which were reflected in some reduction of the chondroitin sulphate.
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  • 12
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    Calcified tissue international 8 (1971), S. 228-236 
    ISSN: 1432-0827
    Keywords: Skin ; Calcinosis ; Keratin ; Chemistry ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des études histologiques antérieures ont montré que le follicle pileux est particulièrement susceptible de se calcifier, lorsque la peau de rats hypercalcémiques est lésée. Des analyses chimiques et par diffraction aux rayons X du follicule ont confirmé ce résultat. — En se basant sur l'augmentation du calcium et du phosphore, les calcifications débutent dans le tissue folliculaire 6–12 h après une blessure d'intensité moyenne de la peau de rats, ayant reçu du dihydrotachysterol (DHT), et 24–48 h après une blessure similaire chez des rats non injectés. Les diagrammes de diffraction aux rayons X sont diffus. Trois heures après la blessure, on note une augmentation du calcium du tissu folliculaire qui ne semble pas en rapport avec le DHT qui traduit probablement une liaison de calcium plutôt qu'un dépot minéral.
    Abstract: Zusammenfassung Frühere histologische Untersuchungen haben gezeigt, daß der Haarfollikel besonders anfällig für Verkalkungen ist, wenn die Haut von hypercalcämischen Ratten verletzt wird. Dieses Resultat wurde nun durch direkte chemische Bestimmungen und Röntgendiffraktions-analysen von Follikelgewebe bestätigt. Aufgrund der erhöhten Calcium- und Phosphatwerte kann gesagt werden, daß nach einer leichten Quetschung der Haut von Ratten, die mit Dihydrotachysterol (DHT) behandelt wurden, im Haarfollikelgewebe nach 6–12 Std Mineral-ablagerungen stattfanden, wogegen Kontrollratten mit der gleichen leichten Hautverletzung diese Ablagerungen erst nach 24–48 Std zeigten. Röntgendiffraktionsanalysen ergaben ein diffuses Apatit-Muster. Innerhalb 3 Std nach der Verletzung wurde ein Anstieg des Calcium-gehaltes im Follikelgewebe beobachtet, der nicht im Zusammenhang mit der DHT-Behandlung stand, also nicht eine Mineralablagerung, sondern eher eine Bindung von Calcium widerspiegelte.
    Notes: Abstract Previous histological investigations have shown that the hair follicle is particularly susceptible to mineralization when the skin of hypercalcaemic rats is injured. Direct chemical and X-ray diffraction analyses of follicle tissue have now confirmed this finding. As judged by increases in both calcium and phosphorus, mineral deposits began to form in hair follicle tissue 6–12 h after a mild crush injury to the skin of rats dosed with dihydrotachysterol (DHT), and 24–48 h after a similar injury to the skin of non-dosed rats. X-ray diffraction gave a diffuse apatite pattern. Within 3 h of injury there was a rise in the calcium content of follicle tissue which was not related to DHT-dosing and which was probably a reflection of calcium binding rather than mineral deposition.
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  • 13
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    Calcified tissue international 8 (1971), S. 304-319 
    ISSN: 1432-0827
    Keywords: Chemistry ; Calcium ; Phosphate ; Solubility ; Computer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un programme d'ordinateur a été mis au point pour calculer les activités ioniques du calcium et l'orthophosphate dans un grand nombre de solutions. Dans le cas de solutions synthétiques, les calculs sont vérifiés en comparant les valeurs de pH, obtenues par ordinateur, avec celles observées expérimentalement. Des essais de ce type, avec des solutions possèdant des concentrations de calcium et d'orthophosphate trouvées dans les liquides biologiques et à des valeurs de pH variant de 3.00 à 10.00, indiquent que le programme est adapté pour des applications biologiques. Le programme n'est pas effectif pour des solutions, dans les lesquelles l'ion bromure est la source principale de la force ionique, sans doute, par manque d'équation étendue de Debye-Hückel dans ces circonstances. Aucune formation de complexe de phosphate de sodium n'a été notée à des concentrations biologiques normales.
    Abstract: Zusammenfassung Es wurde ein Computer-Programm ausgearbeitet, um die Ionenaktivitäten von Calcium und Orthophosphat in einer breiten Varietät von Lösungen zu berechnen. Die Berechnungen wurden bei synthetischen Lösungen durch Vergleiche zwischen den auf diese Weise errechneten pH-Werten und den experimentell gefundenen kontrolliert. Diese Art Kontrollen mit Calcium-und Orthophosphatkonzentrationen, wie sie in biologischen Flüssigkeiten gefunden werden, und mit pH-Werten zwischen 3,0 und 10,0 wies darauf hin, daß das Programm für biologische Anwendungen geeignet war. Das Programm konnte nicht benützt werden für solche Lösungen, bei welchen hauptsächlich das Bromidion zur Einstellung der Ionenstärke verwendet wurde, vermutlich weil die erweiterte Debye-Hückel-Gleichung unter diesen Umständen nicht anwendbar ist. Die Bildung eines Natriumphosphat-Komplexes unter normalen biologischen Konzentrationen konnte nicht nachgewiesen werden.
    Notes: Abstract A computer program has been designed to calculate the ionic activities of calcium and orthophosphate in a wide variety of solutions. In the case of synthetic solutions the calculations were checked by comparing the computed pH values with those observed experimentally. Tests of this type with solutions having the concentrations of calcium and orthophosphate found in biological fluids and with pH values ranging from pH 3.0–10.0 indicated that the program was suitable for biological applications. The program was not effective for solutions in which the bromide ion was a principal source of ionic strength probably because of the failure of the extended Debye-Hückel equation under those circumstances. No evidence for the formation of any sodium phosphate complex at normal biological concentrations could be found.
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  • 14
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    Calcified tissue international 10 (1972), S. 171-197 
    ISSN: 1432-0827
    Keywords: Amorphous ; Crystalline ; Calcium phosphate ; Chemistry ; Composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des échantillons non lavés de phosphate de calcium amorphe (ACP) contiennent une fraction labile, non remplaçable, riche en phosphate acide avec un rapport Ca/P faible: cette fraction est perdue de façon irréversible au cours du lavage. De l'ACP frais, précipité entre pH 6.6–10.6, varie dans un rapport molaire Ca/P de 1.18 à 1.50 et dans un rapport HPO 4 2− /P total de 33.0% à 10.1%. A pH 7.40, de l'ACP frais a un rapport molaire Ca/P de 1.36±0.02 et contient 22.8 (±2.2)% HPO 4 2− . Les résultats obtenus avec du précipité non lavé ne peuvent s'expliquer par du Ca2+ emprisonné et de l'HPO 4 2− ou du Na+, Cl− et CO 3 2− exogènes. Les phosphates de calcium amorphes constituent une classe de sels ayant des caractères chimiques variables et des propriétés physiques identiques, comparables au verre. Le CaHPO4·xH2O non cristallin peut être un ACP, surtout au cours des phases précoces de formation. A des pH physiologiques, l'ACP se transforme en petits cristaux applatis contenant de fortes quantités de phosphate acide facilement remplaçable. Le fait de laver la couche de surface produit un changement chimique dans les nouveaux cristaux: des cristaux non lavés donnent des diagrammes de diffraction d'apatite peu cristallins, ainsi que des spectres infra-rouges peu nets, intermédiaires entre des apatites et du phosphate octocalcique. Des explications structurales sont proposées et les compositions minérales amorphe/cristalline de l'os et du cartilage sont recalculées.
    Abstract: Zusammenfassung Ungewaschene Proben von amorphem Calciumphosphat (ACP) enthalten eine unersetzliche labile Fraktion, welche reich an saurem Phosphat ist und ein niederes Ca/P-Verhältnis hat und welche während des Waschprozesses unwiderruflich verloren geht. Natives ACP, welches im pH-Bereich 6,6–10,6 ausgefällt wurde, variierte im molaren Ca/P-Verhältnis zwischen 1,18 und 1,50 und in HPO 4 2− /totales P zwischen 33,0 und 10,1%. Bei pH 7,40 hatte natives ACP ein molares Ca/P-Verhältnis von 1,36±0,02 und enthielt 22,8 (±2,2)% HPO 4 2− . Die Werte beim ungewaschenen Niederschlag rühren weder von aus dem Überstand aufgenommenem Ca2+ und HPO2−, noch von außen kommendem Na+, Cl− und CO 3 2− her. Die amorphen Calciumphosphate werden als eine Klasse von Salzen erkannt, welche veränderliche chemische, aber identische glasartige physicochemische Eigenschaften haben. Nicht kristallines CaHPO4·xH2O kann auch ein ACP sein, besonders in den frühen Bildungsstadien. Bei physiologischem pH verwandelt sich ACP in kleine plattenförmige Kristalle, welche große Mengen von leicht ersetzbarem saurem Phosphat enthalten. Das Waschen dieser Oberflächenschicht erzeugte chemische Veränderungen in den resultierenden Kristallen; ungewaschene Kristalle zeigten ein Diffraktionsmuster, das nur schwach demjenigen des kristallinen Aspatites glich, aber ein schlecht aufgelöstes Infrarotspektrum, welches zwischen Apatit und Octocalciumphosphat war. Es werden strukturelle Erklärungen für alle diese Phenomena diskutiert, und revidierte amorph/kristalline Mineralzusammensetzungen von Knochen und Knorpel wurden neu berechnet.
    Notes: Abstract Unwashed samples of amorphous calcium phosphate (ACP) contain an irreplaceable labile fraction, rich in acid phosphate and low in Ca/P ratio, which is irreversibly lost during the washing process. Native ACP precipitated in the pH range 6.6–10.6 varied in Ca/P molar ratio from 1.18 to 1.50 and in HPO 4 2− /total P from 33.0% to 10.1%. At pH 7.40, native ACP had a Ca/P molar ratio of 1.36±0.02 and contained 22.8 (±2.2)% HPO 4 2− . Unwashed precipitate data could not be attributed to either trapped supernatant Ca2+ and HPO 4 2− or extraneous Na+, Cl−, and CO 3 2− . The amorphous calcium phosphates are recognized as a class of salts having variable chemical but identical glass-like, physicochemical properties. Non-crystalline CaHPO4·xH2O may also be an ACP, especially during early formative stages. At physiological pH, ACP transforms to small platy crystals containing large amounts of readily-replaceable acid phosphate. Washing this surface layer produced chemical alterations in the resultant crystals; unwashed crystals had poorly-crystalline apatitic diffraction patterns but exhibited poorly-resolved infrared spectra intermediate between apatite and octacalcium phosphate. Structural explanations for all these phenomena are discussed, and revised bone and cartilage amorphous/crystalline mineral compositions have been re-calculated.
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    Calcified tissue international 23 (1977), S. 39-44 
    ISSN: 1432-0827
    Keywords: Dental cementum ; Collagen ; Protein ; Chemistry
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    Topics: Biology , Medicine , Physics
    Notes: Summary Cyanogen bromide (CNBr) peptides were prepared of the insoluble collagen of bovine dental cementum. Following chromatographic separation, the peptides were identified by their amino-acid composition. Type I collagen ([α1(I)]2α2) accounted for more than 90% of the organic matrix, while Type III collagen ([α1(III)]3) was present at a level of approximately 5%. Amino-acid analyses revealed that the CNBr peptides from α1(I) and α2 chains of cementum closely resembled the corresponding peptides from calf skin. The only systematic difference was a higher level of hydroxylation of prolyl and lysyl residues of the cementum peptides.
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    Calcified tissue international 23 (1977), S. 87-94 
    ISSN: 1432-0827
    Keywords: Calcium ; Osteoporosis ; Lactation ; Chemistry
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    Topics: Biology , Medicine , Physics
    Notes: Summary The calcium homeostatic mechanism was challenged in adult female rats by feeding them a calcium-deficient diet containing oxalate, and by subjecting them to pregnancy and lactation. The regimen caused a substantial weight loss, especially in those animals which reared their young well. Severe hypocalcaemia was observed in the lactating rats. Serum-P was slightly elevated. The content of hydroxyproline in serum was considerably elevated, reflecting the degree of calcium deprivation. Serum proteins were least influenced. The calcium depriving regimen reduced the growth of long bones, but did not stop it. The ash content of the bones was considerably reduced, the degree of reduction depended on the degree of calcium deprivation. Ash as percentage of total bone organ was reduced, but not to the same extent as total ash. Analyses of different parts of femur showed that the proximal and distal parts had lost more bone mineral than the diaphyseal shaft. The ash content of cortical bone tissue from the femur was estimated by a volumetric method. No differences were observed between test groups and controls, indicating that no measurable amounts of bone mineral had been removed from the walls of the vascular canals or by osteocytic osteolysis. Planimetric determinations on cross sections from femora disclosed that a great amount of bone had been removed from the endosteal surface of the diaphysis, while the periosteal surface demonstrated reduced bone apposition.
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    Calcified tissue international 8 (1971), S. 197-210 
    ISSN: 1432-0827
    Keywords: Fluorescence ; Calcium ; Collagen ; Chemistry ; Bone ; Dentine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des composants fluorescents de l'os et la dentine sont séparés des hydrolysats alcalins de leur marice sur des colonnes Sephadex C25 CM d'échange cationique. Les concentrations en fluorescence et le spectre d'excitation (λ max 330 nm) et d'émission (λ max 395 nm) sont les mêmes que ceux observés au niveau des matrices intactes et gélatinisées. Les paramètres de fluorescence ne sont pas altérés par hydrolyse. La filtration sur gel à l'aide de colonnes Sephadex G 10 perment de différencier le matériel isolé en deux composants, ayant la même fluorescence et la même absorption UV. La fluorescence est indépendante de pH de 3.5–9.5. Des études de dialyse et de filtration sur gel de matrices gélatinisées indiquent une association étroite du matériel fluorescent avec les chaines polypeptidiques de collagène.
    Abstract: Zusammenfassung Fluorescierende Bestandteile aus Knochen und Dentin wurden in Sephadex C25 CM Kationen-Austauschersäulen von alkalischen Hydrolysaten ihrer Matrices getrennt. Die Fluorescenzintensitäten sowie die Erregungs- (λ max 330 nm) und Emissions- (λ max 395 nm) Spektren waren dieselben wie bei intakten und gelatinisierten Matrices. Die Fluorescenzparameter wurden durch die Hydrolyse nicht verändert. Eine Gelfiltration über Sephadex-G10-Säulen trennte das isolierte Material in 2 Komponenten auf, welche gleiche Fluorescenz- und UV-Absorptionseigenschaften zeigten. Im pH-Bereich zwischen 3,5 und 9,5 war die Fluorescenz unabhängig vom pH. Dialysierversuche sowie Gelfiltrationsexperimente mitden gelatinisierten Matrices zeigten eine starkgefügte Bindung des fluorescierenden Materials mit den Polypeptidketten des Kollagens.
    Notes: Abstract Fluorescent components in bone and dentine were separated from alkaline hydrolysates of their matrices on Sephadex C25 CM cationic exchange columns. The fluorescence levels, and the excitation (λ max 330 nm) and emission (λ max 395 nm) spectra, were the same as those observed in the intact and gelatinised matrices. The fluorescence parameters were unaltered by the hydrolysis procedure. Gel filtration on Sephadex G. 10 columns further resolved the isolated material into two components with the same fluorescence and UV absorption properties. The fluorescence was independent of pH over the range 3.5–9.5. Dialysis and gel filtration studies on the gelatinised matrices indicated a firmly-bonded association of the fluorescent material with the collagen polypeptide chains.
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    Calcified tissue international 12 (1973), S. 125-136 
    ISSN: 1432-0827
    Keywords: Mineralization ; Molt ; Isopod ; Chemistry ; Light microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Au cours de la phase inhabituelle de mue d'un isopode d'eau courante,Lirceuts brachyrus, la moitié postérieure de l'exosquelette est éliminée 24 heures avant la moitié antérieure. A ce stade, une reminéralisation se développe dans la partie postérieure alors que la partie antérieure est dans un stade de pré-mue. Le pourcentage de différence en calcium dans les deux moitiés à mi-mue et mue complète est respectivement de 22% (p〈0.01) et 33% (p〈0.01), indiquant une complexation du calcium pendant la mue. La rapidité de la reminéralisation est illustrée par le fait que le contenu minéral total double dans la partie postérieure entre la mi-mue et la mue totale et dans la partie antérieure entre la fin de la mue et un jour après. Le carbonate de calcium, sous forme de calcite, a pu être identifié par diffraction électronique de coupes fines des téguments.
    Abstract: Zusammenfassung Während der ungewöhnlichen Häutungssequenz des Frischwasser-IsopodenLirceus brachyurus (Harger) wird die hintere Hälfte des äußeren Skeletts 24 Std vor der vorderen Hälfte abgestoßen. In der halbgehäuteten Phase erfolgt Remineralisation im hinteren Teil, während der vordere Teil in einem Vorhäutungszustand ist. Der prozentuale Unterschied des Calciums in den zwei Hälften bei Halb- und Vollhäutungszustand ist 22% (p〈0,01) bzw. 33% (p〈0,01), was andeutet, daß Calcium während der Häutung abgesondert wird. Die Geschwindigkeit der Remineralisation erhellt aus der Tatsache, daß sich der Gesamtmineralgehalt im hinteren Teil zwischen Halt- und Vollhäutung, in der vorderen Hälfte jedoch zwischen Endhäutung und einem Tag nach der Häutung verdoppelt. Calciumcarbonat in kristalliner Calcitform wurde mittels Elektronendiffraktion von dünnen Hautschnitten nachgewiesen.
    Notes: Abstract During the unusual molt sequence of the fresh-water isopod,Lirceus brachyrus (Harger), the posterior half of the exoskeleton is shed 24 hours before the anterior half. At the half-molt stage, occurs in the posterior part while the anterior portion is in a pre-molt condition. The percentage difference in calcium in the two halves at half-molt and full-molt is22 (p〈0.01) and33 (p〈0.01) respectively, an indication that calcium is sequestered during The rapidity of remineralization is illustrated by the fact that the total mineral content doubles in the posterior part between half and full molt and in the anterior half between the end of molt and one day after ecdysis. Calcium carbonate in the calcite cystalline form was demonstrated by electron diffraction of thin sections of the integument.
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    Calcified tissue international 13 (1973), S. 259-270 
    ISSN: 1432-0827
    Keywords: Fluorapatite ; Exchange ; Chemistry ; Crystallography
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    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un échantillon minéral provenant de Burgess, Canada s'est révélé être un speciment exceptionnellement pur de fluoroapatite après analyse chimique et cristallographique. La composition globale de cet échantillon est la suivante: $$(Ca^2 )9.98(Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )0.02(PO_4^{3 - } )5.98(HCO_3^ - ,CO_3^{2 - } )0.02(F^ - )2$$ . L'axe cristallographique C est de 6.865 A et l'axe a de 9.374 A. Des expériences d'échanges réalisés à l'aide de45Ca,32P et18F indiquent la présence de gros cristallites de surface spécifique de l'ordre de 1 m2/g. Il apparait que l'interprétation physique des processus d'échange ne nécessite pas l'existence de compartiments séparés, avec chacun son propre facteur cinétique, les échanges semblent être simplement liés à un changement exponentiel dans l'énergie libre de la réaction. Pour la réaction suivante: $$(Ca)_5 (PO_4 )_3 OH solide + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F solide + (OH^ - )$$ , la constante thermodynamique de 101.26 a été calculée, suggérant que le fluorapatite se forme toujours aux dépens de l'hydroxyapatite dans des conditions physiologiques. Cette transformation se continue en abaissant le pH.
    Abstract: Zusammenfassung Eine Mineralprobe aus Burgess, Kanada, erwies sich nach chemischer und kristallographischer Analyse als außergewöhnlich reines Fluorapatit. Die Gesamtzusammensetzung entspricht: $$(Ca^{2 + } )_{9,98} (Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )_{0,02} (PO_4^{3 - } )_{5,98} (HCO_3^ - ,CO_3^{2 - } )_{0,02} (F^ - )_2 $$ . Die kristallographische c-Achse wurde bestimmt und ergab 6,865 Å, und die a-Achse ergab 9,374 Å. Austauschwerte, welche durch Anwendung von45Ca,32P und18F erhalten wurden, deuteten auf große Kristalliten mit einer spezifischen Oberfläche von ca. 1 m2/g. Die Befunde deuten darauf hin, daß für die physikalische Erklärung des Austauschvorganges keine separaten Kompartimente mit eigenen kinetischen Faktoren nötig sind, sondern daß der Austausch mit dem exponentiellen Wechsel in der freien Energie der Reaktion in einfacher Beziehung steht. Für die Reaktion $$(Ca)_5 (PO_4 )_3 OH_{in fester Form} + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F_{in fester Form} + (OH^ - )$$ wurde als thermodynamische Konstante 101,26 errechnet, was darauf deutet, daß unter physiologischen Bedingungen immer Fluorapatit auf Kosten von Hydroxyapatit entsteht. Diese Umwandlung wird erhöht, wenn das pH erniedrigt wird.
    Notes: Abstract A mineral specimen from Burgess, Canada, proved upon chemical and crystallographic analyses to be an exceptionally pure sample of fluorapatite. The over-all composition corresponds to $$(Ca^{2 + } )_{9.98} (Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )_{0.02} (PO_4^{3 - } )_{5.98} (HCO_3^ - ,CO_3^{2 - } )_{0.02} (F^ - )_2 $$ . The crystallographic c-axis was determined to be 6.865 Å, and the a-axis 9.374 A. Exchange data obtained by employing45Ca,32P, and18F indicate the presence of large crystallites with a specific surface of the order of 1 m2/g. It is indicated that the physical interpretation of the exchange process does not require the existence of separate departments, each with its own kinetic factor, but that the exchange may be simply related to the exponential change in the free energy of the reaction. For the reaction $$(Ca)_5 (PO_4 )_3 OH_{solid} + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F_{solid} + (OH^ - )$$ the thermodynamic constant has been calculated to be 101.26, implying that fluorapatite always will form at the expense of hydroxyapatite under physiologic conditions. This transformation will be furthered by lowering the pH.
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    ISSN: 1432-0827
    Keywords: Bacterial amphophile ; Purification ; Chemistry ; Resorption ; Ca influx ; Cyclic AMP
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    Topics: Biology , Medicine , Physics
    Notes: Summary The bone resorptive factor and amphipathic antigen (AcA) previously identified by us in preparations fromActinomyces viscosus have been partially purified, characterized chemically, and compared. They elute at the same location on chromatography with Ac 22. The fatty acid composition of AcA and the bone resorptive factor is the same. Some differences in carbohydrate composition are observed. TheActinomyces factor does not affect calcium influx or cyclic AMP in isolated bone cells. Therefore it is concluded that AcA stimulates resorption either by gaining entrance into bone cells or by way of a yet undetermined second messenger.
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    Astrophysics and space science 224 (1995), S. 81-84 
    ISSN: 1572-946X
    Keywords: Chemistry ; Depletions ; Shocks ; IRAS 05338-0624 ; NGC 1333 IRAS 4
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    Topics: Physics
    Notes: Abstract High resolution interferometer and single-dish observations of young, deeply embedded stellar systems reveal a complex chemistry in the circumstellar environments of low to intermediate mass stars. Depletions of gas-phase molecules, grain mantle evaporation, and shock interactions actively drive chemical processes in different regions around young stars. We present results for two systems, IRAS 05338-0624 and NGC 1333 IRAS 4, to illustrate the behavior found and to examine the physical processes at work.
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    Astrophysics and space science 216 (1994), S. 153-154 
    ISSN: 1572-946X
    Keywords: Chemistry ; Molecular Hydrogen ; Cloud Models
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    Topics: Physics
    Notes: Abstract Observations of the CO J=1-0 line are commonly used as a tracer for molecular material in clouds. The ratio of the H2 column density to the integrated intensity of this line,X, is often taken to be constant, despite theoretical and observational uncertainty. We have tried to identify how this ratio depends on cloud parameters, testing a simple theoretical argument suggesting its invariance with respect to density. The apparent constancy can be understood if clouds are clumpy on scales of Av ≈ 1-2 mag.
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    Boundary layer meteorology 85 (1997), S. 197-222 
    ISSN: 1573-1472
    Keywords: Turbulence ; Chemistry ; Closure ; Convective boundary layer
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    Topics: Geosciences , Physics
    Notes: Abstract We study the interactions of chemistry and turbulent mixing of tracersin the convective boundary layer with a second-order closure model,including higher order chemistry terms. In order to limit the number of predictive equations we prescribe the profiles for ¯w¯Θ, ¯w¯θ ¯θ and the lengthscale l. However, for model validation we treat temperature and humidity asinert tracers, and compare the results with profiles observed during theAir Mass Transformation Experiment, and with similarity expressions for thesurface layer. We find good agreement of the mean profiles, but the (co-)variances are slightly underpredicted. Furthermore, the model usesdiagnostic equations expressing third moments of concentration in terms ofsecond moments and their vertical derivatives. They are compared withlarge-eddy model results, showing good agreement and, therefore, thesimplifications are justified. The model is applied to the transport of two gases subject to one bimolecular reaction. The importance of concentration correlations on themean transformation rate is studied. For two gases diffusing in oppositedirections we find for moderate and fast chemistry a 50% and90% decreased transformation rate due to the negatively correlatedconcentrations. These values are similar to large-eddy results of Schumannand Sykes et al. For two bottom-up tracers we find that the covariance ofboth reactive species is either positive or negative, increasing or reducingthe effective transformation rate depending on the Damköhler number (the ratio of the turbulent and the chemistry timescale). A significantdirect influence of chemistry on the flux divergence is found in bothcases. According to the model the effective transport to mid-levels of theboundary layer is increased when two reactive tracers diffuse in oppositedirections, and decreased in the case of two bottom-up tracers.
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  • 24
    ISSN: 1432-0878
    Keywords: Milk ; Fat globule membrane ; Carbohydrates ; Chemistry ; Ruthenium red ; Ultrastructure
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    Topics: Biology , Medicine
    Notes: Summary The fat globules of the cream fractions of human and rat milk were stained with ruthenium red. Under the electron microscope, discrete granules and an amorphous coat of lesser density are seen at the surface of the milk fat globules. Since ruthenium red binds anionic groups selectively, it is probable that the granules containe the greatest concentration of these groups. The cream fraction of rat milk contains hexoses, hexosamines, methylpentoses and sialic acid. Methylpentoses and hexosamines are significantly enriched in the cream fraction. It is concluded that the finding of a surface coat in milk fat globules is in keeping with the Bargmann-Knoop model and suggests a distinct mechanism for carrying certain complex carbohydrates in milk. The role of the negative charges at the outer surface of the membrane coat in maintaining fat globules in suspension and in binding certain cations such as calcium is suggested.
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  • 25
    ISSN: 1573-739X
    Keywords: Antimalarials ; Artemisia annua L ; Artemisinin ; Biosynthesis ; Chemistry ; Clinical trials ; Pharmacology ; Phytochemistry ; Sesquiterpenes ; Toxicology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Artemisinin, a sesquiterpene lactone endoperoxide isolated fromArtemisia annua L., and a number of its semisynthetic derivatives have shown to possess antimalarial properties. They are all eflective againstPlasmodium parasites that are resistant to the newest and commonly used antimalarial drugs. This article gives a survey of the literature dealing with artemisinin-relaled antimalarial issues that have appeared from the end of 1989 up to the beginning of 1994. A broad range of medical and pharmaceutical disciplines is covered, including phytochemical aspects like the selection of high-producing plants, analytical procedures, and plant biotechnology. Furthermore, the organic synthesis of artemisinin derivatives is discussed, as well as their mechanism of action and antimalarial activity, metabolism and pharmacokinetics, clinical studies, sideeffects and toxicology, and biological activities other than antimalarial activity.
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    Pharmacy world & science 10 (1988), S. 93-95 
    ISSN: 1573-739X
    Keywords: Anthracyclines ; Chemistry ; Drug stability ; Mitomycins
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    Pharmacy world & science 10 (1988), S. 101-116 
    ISSN: 1573-739X
    Keywords: Chemistry ; Chromatography ; Etoposide ; Immunoassay ; Metabolism ; Podophyllotoxin ; Pharmacokinetics ; Teniposide
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    Topics: Chemistry and Pharmacology
    Notes: Abstract Etoposide (VP 16-213) and teniposide (VM 26) are semisynthetic epipodophyllotoxin derivatives active against a variety of tumours. The clinical efficacy has led to an increasing interest in these compounds. This review presents information on the mechanism of action, biochemical pharmacology, bioanalysis, metabolism and pharmacokinetics of etoposide and teniposide.
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    Pharmacy world & science 13 (1991), S. 109-118 
    ISSN: 1573-739X
    Keywords: Chemistry ; Consumer product safety ; Drug packaging ; Environmental pollution ; Plasticizers ; Polyvinyls
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    Topics: Chemistry and Pharmacology
    Notes: Abstract In this report the state of the art with respect to PVC as pharmaceutical packaging material is described. A general introduction into the applications of PVC is followed by a description of its production process. The metabolic effects of the monomer of PVC, vinyl chloride and of the most commonly used plasticizer diethylhexylphthalate are mentioned. Special attention is given to the pharmaceutical properties of plasticized PVC bags in comparison to other plastics and the environmental aspects of waste PVC disposal. Although there are emotional and political queries regarding the future use of PVC as a (pharmaceutical) packaging material, we conclude that there is no scientific justification for a total or partial ban of PVC. PVC will remain a fact of life as a cheap, versatile, high-performance and well-investigated plastic material for medical and pharmaceutical applications, to be replaced by newer plastics only for certain well-defined indications where the requirements of the plastic to be used are so specific that it will economically and technically be justified to use another polymer. Community and hospital pharmacists have to be prepared for a role in intake of waste plastic disposables, probably against deposit money, in order to fulfil the logistics needed for recycling.
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    Journal of science education and technology 5 (1996), S. 193-201 
    ISSN: 1573-1839
    Keywords: Chemistry ; chemistry education ; multiple intelligences ; imagery ; visual-spatial thinking
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    Topics: Natural Sciences in General , Technology
    Notes: Abstract Chemistry has evolved from a science dominated by mathematics into a science highly dependent on spatial-visual intelligence. Yet the chemical content of introductory courses remains taught essentially the same as 40–50 years ago. Chemistry, today, is recognized by chemists as the molecular science. Yet, school chemistry is alienated from that perception. Thanks to the computer, young people are more comfortable with visual imaging than their instructors were at the same age. Thus the time is rife to reinvigorate chemistry education by means of the visual-spatial approach, an approach wholly in conformance with the way modern chemistry is thought about and practiced.
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    Pharmacy world & science 8 (1986), S. 245-251 
    ISSN: 1573-739X
    Keywords: Analysis ; Antineoplastic agents ; Biosynthesis ; Botany ; Chemistry ; Cytotoxins ; Eupatorium cannabium ; Sesquiterpenes
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    Topics: Chemistry and Pharmacology
    Notes: Abstract A review onEupatorium cannabinum L. is given, including botany, history and constituents. The sesquiterpene lactones are discussed in more detail, covering their biosynthesis, isolation, analysis and biological activity. Special attention is paid to the cytotoxic and antitumour activities of the sesquiterpene lactones.
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    Pharmacy world & science 9 (1987), S. 305-314 
    ISSN: 1573-739X
    Keywords: Atrial natriuretic factor ; Blood pressure ; Chemistry ; Diuresis ; Homeostasis ; Kidney ; Muscle, smooth ; Natriuresis ; Receptors, endogenous compounds ; Renin-angiotensin system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It is now known that cardiac atria play an important role in blood pressure and volume regulation. Mechanical distension of the atria results in the release of a potent diuretic and natriuretic agent or agents termed the atrial natriuretic factor (ANF). Several structurally related forms of ANF exist in man and it is thought that these represent precursory forms of a single optimally active molecule and/or the presence of more than one form of active ANF. The chemical structure of ANF between different mammalian species is similar. ANF receptors have been identified in kidney, brain, vascular endothelial and smooth muscle cells, tracheal and bronchial smooth muscle and the adrenal glands of many mammalian species, including man. This would suggest that ANF influences blood pressure and volume homoeostasis by affecting any one of a number of biochemical or physiological mechanisms via different target tissues. ANF is now considered a potentially valuable therapeutic agent for the treatment of hypertension and congestive heart failure. Synthesis of potent receptor antagonists could be extremely useful in the treatment of various clinical situations which are produced or complicated by endogenously produced ANF, such as chronic orthostatic hypotension.
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  • 32
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    Plant systematics and evolution 171 (1990), S. 1-14 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Compositae ; Chemistry ; systematics ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The broad knowledge of the chemistry of theCompositae allows the discussion of its relevance for the systematics and evolution within the family. Furthermore a separation into subfamilies can be supported by the observed differences in the distribution of the main constituents in the tribes.
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  • 33
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    Earth, moon and planets 88 (2000), S. 35-58 
    ISSN: 1573-0794
    Keywords: Chemistry ; interplanetary dust particles (IDPs) ; Leonids ; meteor trails ; meteoroids ; meteors ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The cometary Leonid meteoroids represent a size range in between largest carbon-richIDPs and the smallest CI meteorites. Their dustball structure and chemistry offer anopportunity to constrain hierarchical dust accretion inferred from petrologic studies ofaggregate and cluster IDPs. The Leonid shower meteoroids of known ``comet ejection''ages provide an opportunity to study space weathering of cometary dust over periodsof up to several hundred years. The meteors and aggregate and cluster IDPs displaycontinuous thermal modification of organics and volatile element (Na, K-bearing phases), that occur as discrete minerals and amorphous solids each different response during kinetically controlled ablation. Leonid meteoroids are not excessively Na-rich. The occurrences of Leonid meteors can now be accurate predicted and combined withknowledge better models for the settling rates, collections of surviving dust becomea comet nucleus-sampling mission.
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  • 34
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    Astrophysics and space science 233 (1995), S. 125-137 
    ISSN: 1572-946X
    Keywords: Interstellar Medium ; Dark Clouds ; Chemistry ; Bistability ; C-shock Waves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Shock waves perturb the chemical state of the interstellar gas. We consider the effects of C-shocks on the composition of molecular clouds, for a range of values of the pre-shock gas density and magnetic induction. The time required to re-establish equilibrium in the post-shock gas depends on the initial conditions and can become very large. The significance of the two known chemical phases of dark clouds and of bistability is considered in this context.
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  • 35
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    Astrophysics and space science 233 (1995), S. 161-164 
    ISSN: 1572-946X
    Keywords: Stars ; Chemistry ; Diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have assessed the role of diffusion in determining chemical abundances in molecular interface regions. Chemical models have been developed which include the appropriate diffusion terms and that are appropriate to a narrow diffusion region (∼0.01pc) that may exist at the interface between a dark core and a hot, shocked T-Tauri wind. We have assumed pressure balance throughout and have calculated the chemical abundances as functions of time and position through the interface. The results show that significant enhancements of detectable molecules/transitions are expected (e.g. CO J=6→5, OH and CH). Using a realistic value of the diffusion coefficient a diffusive region of dimension 0.01pc may be established within about 104 years. In general it seems likely that diffusion processes are highly significant on these and smaller lengthscales.
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-07-08
    Description: Separation and purification are critical industrial processes for separating components of chemical mixtures, and these processes account for about half of industrial energy usage (1). Gas mixtures of compounds with very similar physical properties are particularly difficult to separate. On pages 137 and 141 of this issue, Cadiau et al. (2) and Cui et al. (3), respectively, show that microporous materials can be designed to have high adsorption capacity and selectivity for particular hydrocarbons, enabling energy-efficient separation. Author: Jerry Y. S. Lin
    Keywords: Chemistry
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-05-27
    Description: Biomass-degrading microorganisms use lytic polysaccharide monooxygenase (LPMO) enzymes to help digest cellulose, chitin, and starch. By cleaving otherwise inaccessible crystalline cellulose chains, these enzymes provide access to hydrolytic enzymes. LPMOs are of interest to biotechnology because efficient depolymerization of cellulose is a major bottleneck for the production of biologically based chemicals and fuels. On page 1098 of this issue, Kracher et al. (1) compare LPMO-reducing substrates in fungi from different taxonomic groups and lifestyles, based on both biochemical and genomic evidence. The results provide insights into reductive activation of LPMO that are important for developing more efficient industrial enzymes for lignocellulose biorefineries. Author: Angel T. Martínez
    Keywords: Chemistry
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  • 38
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    American Association for the Advancement of Science (AAAS)
    In: Science
    Publication Date: 2016-03-25
    Description: Author: Marc S. Lavine
    Keywords: Chemistry
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 39
    Publication Date: 2002-10-05
    Description: The detection of single-nucleotide polymorphisms in pathogenic microorganisms has normally been carried out by trial and error. Here we show that DNA hybridization with high-density oligonucleotide arrays provides rapid and convenient detection of single-nucleotide polymorphisms in Plasmodium falciparum, despite its exceptionally high adenine-thymine (AT) content (82%). A disproportionate number of polymorphisms are found in genes encoding proteins associated with the cell membrane. These genes are targets for only 22% of the oligonucleotide probes but account for 69% of the polymorphisms. Genetic variation is also enriched in subtelomeric regions, which account for 22% of the chromosome but 76% of the polymorphisms.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Volkman, Sarah K -- Hartl, Daniel L -- Wirth, Dyann F -- Nielsen, Kaare M -- Choi, Mehee -- Batalov, Serge -- Zhou, Yingyao -- Plouffe, David -- Le Roch, Karine G -- Abagyan, Ruben -- Winzeler, Elizabeth A -- GM61351/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2002 Oct 4;298(5591):216-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12364807" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Chromosomes/genetics ; DNA, Protozoan/genetics ; *Genes, Protozoan ; Genetic Variation ; Genome, Protozoan ; Membrane Proteins/*genetics ; Molecular Sequence Data ; Nucleic Acid Hybridization ; Oligonucleotide Probes ; Plasmodium falciparum/*genetics ; *Polymorphism, Single Nucleotide ; Protozoan Proteins/*genetics ; Sequence Analysis, DNA
    Print ISSN: 0036-8075
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  • 40
    Publication Date: 2002-04-06
    Description: Higher order chromatin structure presents a barrier to the recognition and repair of DNA damage. Double-strand breaks (DSBs) induce histone H2AX phosphorylation, which is associated with the recruitment of repair factors to damaged DNA. To help clarify the physiological role of H2AX, we targeted H2AX in mice. Although H2AX is not essential for irradiation-induced cell-cycle checkpoints, H2AX-/- mice were radiation sensitive, growth retarded, and immune deficient, and mutant males were infertile. These pleiotropic phenotypes were associated with chromosomal instability, repair defects, and impaired recruitment of Nbs1, 53bp1, and Brca1, but not Rad51, to irradiation-induced foci. Thus, H2AX is critical for facilitating the assembly of specific DNA-repair complexes on damaged DNA.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4721576/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4721576/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Celeste, Arkady -- Petersen, Simone -- Romanienko, Peter J -- Fernandez-Capetillo, Oscar -- Chen, Hua Tang -- Sedelnikova, Olga A -- Reina-San-Martin, Bernardo -- Coppola, Vincenzo -- Meffre, Eric -- Difilippantonio, Michael J -- Redon, Christophe -- Pilch, Duane R -- Olaru, Alexandru -- Eckhaus, Michael -- Camerini-Otero, R Daniel -- Tessarollo, Lino -- Livak, Ferenc -- Manova, Katia -- Bonner, William M -- Nussenzweig, Michel C -- Nussenzweig, Andre -- Z99 CA999999/Intramural NIH HHS/ -- New York, N.Y. -- Science. 2002 May 3;296(5569):922-7. Epub 2002 Apr 4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11934988" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; B-Lymphocytes/immunology/physiology ; Base Sequence ; Cell Aging ; Cell Cycle ; Cells, Cultured ; *Chromosome Aberrations ; DNA Damage ; *DNA Repair ; Female ; Gene Targeting ; Histones/chemistry/*genetics/*physiology ; Immunoglobulin Class Switching ; Infertility, Male/genetics/physiopathology ; Lymphocyte Count ; Male ; Meiosis ; Mice ; Mice, Knockout ; Molecular Sequence Data ; Mutation ; Phosphorylation ; *Recombination, Genetic ; Spermatocytes/physiology ; T-Lymphocytes/immunology/physiology
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  • 41
    Publication Date: 2002-06-22
    Description: Positive-strand RNA viruses such as poliovirus replicate their genomes on intracellular membranes of their eukaryotic hosts. Electron microscopy has revealed that purified poliovirus RNA-dependent RNA polymerase forms planar and tubular oligomeric arrays. The structural integrity of these arrays correlates with cooperative RNA binding and RNA elongation and is sensitive to mutations that disrupt intermolecular contacts predicted by the polymerase structure. Membranous vesicles isolated from poliovirus-infected cells contain structures consistent with the presence of two-dimensional polymerase arrays on their surfaces during infection. Therefore, host cytoplasmic membranes may function as physical foundations for two-dimensional polymerase arrays, conferring the advantages of surface catalysis to viral RNA replication.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lyle, John M -- Bullitt, Esther -- Bienz, Kurt -- Kirkegaard, Karla -- AI-42119/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 2002 Jun 21;296(5576):2218-22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12077417" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; HeLa Cells ; Humans ; Hydrogen-Ion Concentration ; Inclusion Bodies, Viral/metabolism/ultrastructure ; Microscopy, Electron ; Models, Molecular ; Molecular Sequence Data ; Mutation ; Nucleic Acid Conformation ; Poliovirus/*enzymology/physiology ; Protein Conformation ; Protein Structure, Quaternary ; Protein Structure, Tertiary ; RNA Replicase/*chemistry/isolation & purification/*metabolism/ultrastructure ; RNA, Viral/biosynthesis/*metabolism ; Viral Core Proteins/metabolism ; Virus Replication
    Print ISSN: 0036-8075
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  • 42
    Publication Date: 2002-11-02
    Description: The interaction of climate and the timing of low tides along the West Coast of the United States creates a complex mosaic of thermal environments, in which northern sites can be more thermally stressful than southern sites. Thus, climate change may not lead to a poleward shift in the distribution of intertidal organisms, as has been proposed, but instead will likely cause localized extinctions at a series of "hot spots." Patterns of exposure to extreme climatic conditions are temporally variable, and tidal predictions suggest that in the next 3 to 5 years "hot spots" are likely to appear at several northern sites.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Helmuth, Brian -- Harley, Christopher D G -- Halpin, Patricia M -- O'Donnell, Michael -- Hofmann, Gretchen E -- Blanchette, Carol A -- New York, N.Y. -- Science. 2002 Nov 1;298(5595):1015-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉University of South Carolina, Department of Biological Sciences and Marine Sciences Program, Columbia, SC 29208, USA. helmuth@biol.sc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12411702" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bivalvia/*physiology ; *Body Temperature ; *Climate ; *Ecosystem ; Environment ; Geography ; Pacific Ocean ; Pacific States ; Seasons ; *Seawater ; Temperature ; *Water Movements
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  • 43
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-06-18
    Description: Hundreds of coral species coexist sympatrically on reefs, reproducing in mass-spawning events where hybridization appears common. In the Caribbean, DNA sequence data from all three sympatric Acropora corals show that mass spawning does not erode species barriers. Species A. cervicornis and A. palmata are distinct at two nuclear loci or share ancestral alleles. Morphotypes historically given the name Acropora prolifera are entirely F(1) hybrids of these two species, showing morphologies that depend on which species provides the egg for hybridization. Although selection limits the evolutionary potential of hybrids, F(1) individuals can reproduce asexually and form long-lived, potentially immortal hybrids with unique morphologies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vollmer, Steven V -- Palumbi, Stephen R -- New York, N.Y. -- Science. 2002 Jun 14;296(5575):2023-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA. svollmer@oeb.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12065836" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bayes Theorem ; *Biological Evolution ; Calmodulin/genetics ; Caribbean Region ; Cnidaria/anatomy & histology/*classification/*genetics/physiology ; Collagen/genetics ; DNA, Mitochondrial/genetics ; *Ecosystem ; Environment ; *Genetic Variation ; Haplotypes ; *Hybridization, Genetic ; Introns ; Likelihood Functions ; Polymorphism, Genetic ; Reproduction ; Reproduction, Asexual ; Sequence Analysis, DNA ; Species Specificity
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-05-31
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Demaine, Linda J -- Fellmeth, Aaron X -- New York, N.Y. -- Science. 2003 May 30;300(5624):1375-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉RAND, Santa Monica, CA 90401, USA. demaine@rand.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12775825" target="_blank"〉PubMed〈/a〉
    Keywords: Aluminum Oxide ; Chemical Phenomena ; Chemistry ; Natural Science Disciplines ; Patents as Topic/*legislation & jurisprudence ; Plant Extracts ; Plant Roots ; Titanium ; United States
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  • 45
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-01-16
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Samyn, Yves -- Massin, Claude -- New York, N.Y. -- Science. 2002 Jan 11;295(5553):276-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11789538" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Classification ; *Ecosystem ; Invertebrates/classification ; Plants/classification ; *Publishing
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  • 46
    Publication Date: 2002-12-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Funes, Soledad -- Davidson, Edgar -- Reyes-Prieto, Adrian -- Magallon, Susana -- Herion, Pascal -- King, Michael P -- Gonzalez-Halphen, Diego -- HL59646/HL/NHLBI NIH HHS/ -- TW01176/TW/FIC NIH HHS/ -- New York, N.Y. -- Science. 2002 Dec 13;298(5601):2155.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Instituto de Fisiologia Celular, Universidad Nacional Autonoma de Mexico (UNAM), 04510 D.F., Mexico.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12481129" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Apicomplexa/enzymology/*genetics/ultrastructure ; *Biological Evolution ; Cell Nucleus/genetics ; Chlamydomonas reinhardtii/enzymology/genetics ; Chlorophyta/enzymology/*genetics ; Cloning, Molecular ; DNA, Mitochondrial/genetics ; Electron Transport Complex IV/chemistry/*genetics ; *Gene Transfer, Horizontal ; Genes ; Genes, Protozoan ; Molecular Sequence Data ; Phylogeny ; Plastids/*genetics ; Symbiosis ; Toxoplasma/enzymology/genetics
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-03-16
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sanchez, Pedro A -- New York, N.Y. -- Science. 2002 Mar 15;295(5562):2019-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉International Center for Research in Agroforestry, Post Office Box 30677, Nairobi, Kenya. P.sanchez@cgiar.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11896257" target="_blank"〉PubMed〈/a〉
    Keywords: Africa South of the Sahara ; Agriculture/*methods ; Biomass ; Crops, Agricultural/*growth & development ; *Ecosystem ; Fertilizers ; *Food Supply ; Forestry ; Humans ; Hunger ; Nitrogen ; Nitrogen Fixation ; Phosphates ; Plant Development ; Public Policy ; *Soil ; Trees/growth & development ; United Nations ; Zea mays/growth & development
    Print ISSN: 0036-8075
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  • 48
    Publication Date: 2002-02-09
    Description: Double-stranded RNA-mediated gene interference (RNAi) in Caenorhabditis elegans systemically inhibits gene expression throughout the organism. To investigate how gene-specific silencing information is transmitted between cells, we constructed a strain that permits visualization of systemic RNAi. We used this strain to identify systemic RNA interference-deficient (sid) loci required to spread gene-silencing information between tissues but not to initiate or maintain an RNAi response. One of these loci, sid-1, encodes a conserved protein with predicted transmembrane domains. SID-1 is expressed in cells sensitive to RNAi, is localized to the cell periphery, and is required cell-autonomously for systemic RNAi.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Winston, William M -- Molodowitch, Christina -- Hunter, Craig P -- New York, N.Y. -- Science. 2002 Mar 29;295(5564):2456-9. Epub 2002 Feb 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11834782" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Animals, Genetically Modified ; Caenorhabditis elegans/embryology/*genetics/metabolism ; Caenorhabditis elegans Proteins/chemistry/*genetics/*physiology ; Calmodulin-Binding Proteins/genetics ; Cytoplasm/metabolism ; Embryo, Nonmammalian/physiology ; *Gene Silencing ; Genes, Helminth ; Germ Cells/metabolism ; Green Fluorescent Proteins ; Intestines/metabolism ; Luminescent Proteins/genetics ; Membrane Proteins/chemistry/*genetics/*physiology ; Molecular Sequence Data ; Mosaicism ; Muscle Proteins/genetics ; Muscles/metabolism ; Mutation ; Protein Structure, Tertiary ; RNA, Double-Stranded/*genetics/metabolism ; RNA, Helminth/*genetics/metabolism ; Recombinant Fusion Proteins/metabolism ; Transgenes
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  • 49
    Publication Date: 2003-04-26
    Description: Tubular nanostructures are suggested to have a wide range of applications in nanotechnology. We report our observation of the self-assembly of a very short peptide, the Alzheimer's beta-amyloid diphenylalanine structural motif, into discrete and stiff nanotubes. Reduction of ionic silver within the nanotubes, followed by enzymatic degradation of the peptide backbone, resulted in the production of discrete nanowires with a long persistence length. The same dipeptide building block, made of D-phenylalanine, resulted in the production of enzymatically stable nanotubes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reches, Meital -- Gazit, Ehud -- New York, N.Y. -- Science. 2003 Apr 25;300(5619):625-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12714741" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Motifs ; Amino Acid Sequence ; Amyloid beta-Peptides/chemistry ; Biosensing Techniques ; Birefringence ; Dipeptides/*chemistry ; Microscopy, Electron ; Microscopy, Electron, Scanning ; Molecular Sequence Data ; *Nanotechnology ; Oxidation-Reduction ; Protein Conformation ; Silver ; Solubility ; Spectroscopy, Fourier Transform Infrared
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  • 50
    Publication Date: 2003-08-09
    Description: Amyotrophic lateral sclerosis (ALS) is a progressive, lethal neuromuscular disease that is associated with the degeneration of spinal and brainstem motor neurons, leading to atrophy of limb, axial, and respiratory muscles. The cause of ALS is unknown, and there is no effective therapy. Neurotrophic factors are candidates for therapeutic evaluation in ALS. Although chronic delivery of molecules to the central nervous system has proven difficult, we recently discovered that adeno-associated virus can be retrogradely transported efficiently from muscle to motor neurons of the spinal cord. We report that insulin-like growth factor 1 prolongs life and delays disease progression, even when delivered at the time of overt disease symptoms.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaspar, Brian K -- Llado, Jeronia -- Sherkat, Nushin -- Rothstein, Jeffrey D -- Gage, Fred H -- AG12992/AG/NIA NIH HHS/ -- AG21876/AG/NIA NIH HHS/ -- NS33958/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 2003 Aug 8;301(5634):839-42.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12907804" target="_blank"〉PubMed〈/a〉
    Keywords: Amyotrophic Lateral Sclerosis/pathology/physiopathology/*therapy ; Animals ; Apoptosis ; Base Sequence ; Caspase 9 ; Caspases/metabolism ; Cell Count ; Dependovirus/*genetics ; Disease Models, Animal ; Disease Progression ; Gene Transfer Techniques ; *Genetic Therapy ; *Genetic Vectors/administration & dosage ; Glial Cell Line-Derived Neurotrophic Factor ; Green Fluorescent Proteins ; Insulin-Like Growth Factor I/*genetics ; Luminescent Proteins/genetics ; Male ; Mice ; Mice, Transgenic ; Molecular Sequence Data ; Motor Neurons/pathology/virology ; Muscle, Skeletal/virology ; Nerve Growth Factors/genetics ; *Protein-Serine-Threonine Kinases ; Proto-Oncogene Proteins/metabolism ; Proto-Oncogene Proteins c-akt ; Random Allocation ; Spinal Cord/chemistry/pathology/virology ; Superoxide Dismutase/genetics/metabolism ; Ubiquitin/analysis
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  • 51
    Publication Date: 2003-10-04
    Description: Analysis of the human and mouse genomes identified an abundance of conserved non-genic sequences (CNGs). The significance and evolutionary depth of their conservation remain unanswered. We have quantified levels and patterns of conservation of 191 CNGs of human chromosome 21 in 14 mammalian species. We found that CNGs are significantly more conserved than protein-coding genes and noncoding RNAS (ncRNAs) within the mammalian class from primates to monotremes to marsupials. The pattern of substitutions in CNGs differed from that seen in protein-coding and ncRNA genes and resembled that of protein-binding regions. About 0.3% to 1% of the human genome corresponds to a previously unknown class of extremely constrained CNGs shared among mammals.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dermitzakis, Emmanouil T -- Reymond, Alexandre -- Scamuffa, Nathalie -- Ucla, Catherine -- Kirkness, Ewen -- Rossier, Colette -- Antonarakis, Stylianos E -- New York, N.Y. -- Science. 2003 Nov 7;302(5647):1033-5. Epub 2003 Oct 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Medical Genetics and National Center of Competence in Research (NCCR) Frontiers in Genetics, University of Geneva Medical School and University Hospitals, 1211 Geneva, Switzerland. Emmanouil.Dermitzakis@medecine.unige.ch〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14526086" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Chromosomes, Human, Pair 21/*genetics ; Chromosomes, Mammalian/*genetics ; *Conserved Sequence ; DNA, Intergenic/*genetics ; Discriminant Analysis ; *Evolution, Molecular ; Female ; Genetic Code ; Genome ; Humans ; Male ; Mammals/*genetics ; Molecular Sequence Data ; Polymerase Chain Reaction ; Proteins/genetics ; RNA, Untranslated/genetics ; Selection, Genetic ; Sequence Alignment ; Species Specificity ; Time ; Transcription, Genetic
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  • 52
    Publication Date: 2003-12-20
    Description: Approximately 80% of the maize genome comprises highly repetitive sequences interspersed with single-copy, gene-rich sequences, and standard genome sequencing strategies are not readily adaptable to this type of genome. Methodologies that enrich for genic sequences might more rapidly generate useful results from complex genomes. Equivalent numbers of clones from maize selected by techniques called methylation filtering and High C0t selection were sequenced to generate approximately 200,000 reads (approximately 132 megabases), which were assembled into contigs. Combination of the two techniques resulted in a sixfold reduction in the effective genome size and a fourfold increase in the gene identification rate in comparison to a nonenriched library.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Whitelaw, C A -- Barbazuk, W B -- Pertea, G -- Chan, A P -- Cheung, F -- Lee, Y -- Zheng, L -- van Heeringen, S -- Karamycheva, S -- Bennetzen, J L -- SanMiguel, P -- Lakey, N -- Bedell, J -- Yuan, Y -- Budiman, M A -- Resnick, A -- Van Aken, S -- Utterback, T -- Riedmuller, S -- Williams, M -- Feldblyum, T -- Schubert, K -- Beachy, R -- Fraser, C M -- Quackenbush, J -- New York, N.Y. -- Science. 2003 Dec 19;302(5653):2118-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Institute for Genomic Research (TIGR), 9712 Medical Center Drive, Rockville, MD 20850, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14684821" target="_blank"〉PubMed〈/a〉
    Keywords: Chromosomes, Plant/genetics ; Cloning, Molecular ; Computational Biology ; Contig Mapping ; DNA Methylation ; DNA, Plant/genetics ; Databases, Nucleic Acid ; Expressed Sequence Tags ; Gene Dosage ; Gene Library ; *Genes, Plant ; *Genome, Plant ; Molecular Sequence Data ; Repetitive Sequences, Nucleic Acid ; Retroelements ; Sequence Alignment ; Sequence Analysis, DNA/*methods ; Transcription, Genetic ; Zea mays/*genetics
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  • 53
    Publication Date: 2002-04-27
    Description: Little is known of how plant disease resistance (R) proteins recognize pathogens and activate plant defenses. Rcr3 is specifically required for the function of Cf-2, a Lycopersicon pimpinellifolium gene bred into cultivated tomato (Lycopersicon esculentum) for resistance to Cladosporium fulvum. Rcr3 encodes a secreted papain-like cysteine endoprotease. Genetic analysis shows Rcr3 is allelic to the L. pimpinellifolium Ne gene, which suppresses the Cf-2-dependent autonecrosis conditioned by its L. esculentum allele, ne (necrosis). Rcr3 alleles from these two species encode proteins that differ by only seven amino acids. Possible roles of Rcr3 in Cf-2-dependent defense and autonecrosis are discussed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kruger, Julia -- Thomas, Colwyn M -- Golstein, Catherine -- Dixon, Mark S -- Smoker, Matthew -- Tang, Saijun -- Mulder, Lonneke -- Jones, Jonathan D G -- New York, N.Y. -- Science. 2002 Apr 26;296(5568):744-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Sainsbury Laboratory, John Innes Centre, Norwich NR4 7UH, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11976458" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Amino Acid Sequence ; Base Sequence ; Cladosporium/*physiology ; Cloning, Molecular ; Cysteine Endopeptidases/chemistry/*genetics/*metabolism ; Cysteine Proteinase Inhibitors/pharmacology ; Gene Expression Regulation, Plant ; *Genes, Plant ; Immunity, Innate ; Leucine/analogs & derivatives/pharmacology ; Lycopersicon esculentum/*enzymology/genetics/*microbiology/physiology ; Molecular Sequence Data ; Mutation ; Phenotype ; *Plant Diseases ; Plant Leaves/enzymology ; Plant Proteins/*metabolism ; Plants, Genetically Modified ; Promoter Regions, Genetic ; Recombinant Fusion Proteins/chemistry/metabolism ; Tobacco/genetics ; Transgenes
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  • 54
    Publication Date: 2003-03-22
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mitchell, Charles E -- Reich, Peter B -- New York, N.Y. -- Science. 2003 Mar 21;299(5614):1844-5; author reply 1844-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12649464" target="_blank"〉PubMed〈/a〉
    Keywords: Atmosphere ; Biomass ; California ; *Carbon Dioxide ; Climate ; *Ecosystem ; Fungi/pathogenicity ; Nitrogen ; *Plant Diseases ; Plant Roots/growth & development ; Poaceae/*growth & development/*microbiology ; Temperature
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  • 55
    Publication Date: 2002-04-06
    Description: The conserved Sir2 family of proteins has protein deacetylase activity that is dependent on NAD (the oxidized form of nicotinamide adenine dinucleotide). Although histones are one likely target for the enzymatic activity of eukaryotic Sir2 proteins, little is known about the substrates and roles of prokaryotic Sir2 homologs. We reveal that an archaeal Sir2 homolog interacts specifically with the major archaeal chromatin protein, Alba, and that Alba exists in acetylated and nonacetylated forms. Furthermore, we show that Sir2 can deacetylate Alba and mediate transcriptional repression in a reconstituted in vitro transcription system. These data provide a paradigm for how Sir2 family proteins influence transcription and suggest that modulation of chromatin structure by acetylation arose before the divergence of the archaeal and eukaryotic lineages.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bell, Stephen D -- Botting, Catherine H -- Wardleworth, Benjamin N -- Jackson, Stephen P -- White, Malcolm F -- New York, N.Y. -- Science. 2002 Apr 5;296(5565):148-51.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Medical Research Council (MRC) Cancer Cell Unit, The Hutchison/MRC Research Centre, Hills Road, Cambridge, CB2 2QH, UK. sdb@mole.bio.cam.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11935028" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylation ; Amino Acid Sequence ; Archaeal Proteins/*chemistry/*metabolism ; Chromatin/*metabolism ; DNA/metabolism ; Gene Expression Regulation, Archaeal ; Histone Deacetylases/chemistry/*metabolism ; Molecular Sequence Data ; Molecular Weight ; Protein Binding ; Recombinant Fusion Proteins/chemistry/metabolism ; *Silent Information Regulator Proteins, Saccharomyces cerevisiae ; Sirtuin 2 ; Sirtuins ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ; Sulfolobus/*chemistry/genetics/metabolism ; Templates, Genetic ; Trans-Activators/chemistry/*metabolism ; Transcription, Genetic
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  • 56
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-03-23
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stone, Richard -- New York, N.Y. -- Science. 2002 Mar 22;295(5563):2191.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11910078" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Commerce/economics ; Conservation of Natural Resources ; *Ecosystem ; *Fishes/physiology ; *Food Supply/economics/standards ; Marine Biology ; Oceans and Seas ; Russia
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  • 57
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-03-23
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Withgott, Jay -- New York, N.Y. -- Science. 2002 Mar 22;295(5563):2201-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11910088" target="_blank"〉PubMed〈/a〉
    Keywords: Australia ; Biomass ; California ; *Ecosystem ; Environment ; Food Chain ; Herbicides/administration & dosage/pharmacology ; Mediterranean Region ; Seawater/*parasitology ; Seaweed/drug effects/*physiology
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  • 58
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2002-09-28
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, David -- New York, N.Y. -- Science. 2002 Sep 27;297(5590):2196.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12351768" target="_blank"〉PubMed〈/a〉
    Keywords: Arizona ; *Ecosystem ; Maps as Topic ; *Pinus ; *Trees
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  • 59
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-07-26
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lubick, Naomi -- New York, N.Y. -- Science. 2003 Jul 25;301(5632):451.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12881542" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atlantic Ocean ; Conservation of Natural Resources ; DNA, Mitochondrial/genetics ; *Ecosystem ; Female ; Genetic Variation ; Genetics, Population ; Male ; Mutation ; Population Density ; Population Dynamics ; Time Factors ; *Whales/genetics
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  • 60
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-07-26
    Description: It is well known that hunting dramatically reduced all baleen whale populations, yet reliable estimates of former whale abundances are elusive. Based on coalescent models for mitochondrial DNA sequence variation, the genetic diversity of North Atlantic whales suggests population sizes of approximately 240,000 humpback, 360,000 fin, and 265,000 minke whales. Estimates for fin and humpback whales are far greater than those previously calculated for prewhaling populations and 6 to 20 times higher than present-day population estimates. Such discrepancies suggest the need for a quantitative reevaluation of historical whale populations and a fundamental revision in our conception of the natural state of the oceans.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Roman, Joe -- Palumbi, Stephen R -- New York, N.Y. -- Science. 2003 Jul 25;301(5632):508-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12881568" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atlantic Ocean ; Base Sequence ; Conservation of Natural Resources ; DNA, Mitochondrial/genetics ; *Ecosystem ; Female ; Genetic Variation ; Genetics, Population ; Male ; Molecular Sequence Data ; Population Density ; Population Dynamics ; Time Factors ; *Whales/classification/genetics
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  • 61
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-03-15
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Webster, Paul -- New York, N.Y. -- Science. 2003 Mar 14;299(5613):1642.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12637710" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arctic Regions ; Canada ; *Ecosystem ; Environmental Exposure/*adverse effects ; Environmental Pollutants/*analysis ; Female ; Humans ; Infant ; Infection/epidemiology/etiology ; *Inuits ; Memory ; Risk Factors
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  • 62
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-03-01
    Description: Although curvature of biological surfaces has been considered from mathematical and biophysical perspectives, its molecular and developmental basis is unclear. We have studied the cin mutant of Antirrhinum, which has crinkly rather than flat leaves. Leaves of cin display excess growth in marginal regions, resulting in a gradual introduction of negative curvature during development. This reflects a change in the shape and the progression of a cell-cycle arrest front moving from the leaf tip toward the base. CIN encodes a TCP protein and is expressed downstream of the arrest front. We propose that CIN promotes zero curvature (flatness) by making cells more sensitive to an arrest signal, particularly in marginal regions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nath, Utpal -- Crawford, Brian C W -- Carpenter, Rosemary -- Coen, Enrico -- New York, N.Y. -- Science. 2003 Feb 28;299(5611):1404-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12610308" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Antirrhinum/cytology/*genetics/*growth & development/metabolism ; Base Sequence ; Cell Cycle ; Cell Differentiation ; Cell Division ; Cell Size ; Cyclin D3 ; Cyclins/genetics/metabolism ; Gene Deletion ; *Gene Expression Regulation, Plant ; *Genes, Plant ; Histones/genetics/metabolism ; Molecular Sequence Data ; Mutagenesis, Insertional ; Mutation ; Plant Leaves/anatomy & histology/cytology/*growth & development/metabolism ; Plant Proteins/chemistry/genetics/metabolism ; Surface Properties ; Transcription Factors/chemistry/genetics/*metabolism
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  • 63
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-10-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stokstad, Erik -- Vogel, Gretchen -- New York, N.Y. -- Science. 2003 Oct 24;302(5645):542-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14576384" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Beta vulgaris/genetics/growth & development ; Biotechnology ; Brassica napus/genetics/growth & development ; Crops, Agricultural/*genetics/growth & development ; *Ecosystem ; *Environment ; Great Britain ; Herbicides ; *Plants, Genetically Modified/growth & development ; Zea mays/genetics/growth & development
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  • 64
    Publication Date: 2003-03-29
    Description: Volcanic aerosols from the 1991 Mount Pinatubo eruption greatly increased diffuse radiation worldwide for the following 2 years. We estimated that this increase in diffuse radiation alone enhanced noontime photosynthesis of a deciduous forest by 23% in 1992 and 8% in 1993 under cloudless conditions. This finding indicates that the aerosol-induced increase in diffuse radiation by the volcano enhanced the terrestrial carbon sink and contributed to the temporary decline in the growth rate of atmospheric carbon dioxide after the eruption.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gu, Lianhong -- Baldocchi, Dennis D -- Wofsy, Steve C -- Munger, J William -- Michalsky, Joseph J -- Urbanski, Shawn P -- Boden, Thomas A -- New York, N.Y. -- Science. 2003 Mar 28;299(5615):2035-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Environmental Sciences Division, Building 1509, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6335, USA. lianhong-gu@ornl.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12663919" target="_blank"〉PubMed〈/a〉
    Keywords: Aerosols ; *Atmosphere ; *Carbon Dioxide/metabolism ; Climate ; *Ecosystem ; Mathematics ; Models, Statistical ; Nonlinear Dynamics ; Philippines ; *Photosynthesis ; Regression Analysis ; Scattering, Radiation ; Seasons ; Sunlight ; Temperature ; Trees/*metabolism ; *Volcanic Eruptions
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  • 65
    Publication Date: 2003-08-16
    Description: Geochemical anomalies and growth discontinuities in Porites corals from western Sumatra, Indonesia, record unanticipated reef mortality during anomalous Indian Ocean Dipole upwelling and a giant red tide in 1997. Sea surface temperature reconstructions show that although some past upwelling events have been stronger, there were no analogous episodes of coral mortality during the past 7000 years, indicating that the 1997 red tide was highly unusual. We show that iron fertilization by the 1997 Indonesian wildfires was sufficient to produce the extraordinary red tide, leading to reef death by asphyxiation. These findings highlight tropical wildfires as an escalating threat to coastal marine ecosystems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Abram, Nerilie J -- Gagan, Michael K -- McCulloch, Malcolm T -- Chappell, John -- Hantoro, Wahyoe S -- New York, N.Y. -- Science. 2003 Aug 15;301(5635):952-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia. nerilie.abram@anu.edu.au〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12920295" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Anthozoa/*growth & development ; Atmosphere ; Biomass ; Dinoflagellida/growth & development ; *Ecosystem ; *Eutrophication ; *Fires ; Indian Ocean ; Indonesia ; Iron ; Phytoplankton/growth & development ; Population Dynamics ; Temperature
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-12-20
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Elena, Santiago F -- Sanjuan, Rafael -- New York, N.Y. -- Science. 2003 Dec 19;302(5653):2074-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Instituto de Biologia Molecular y Celular de Plantas, Consejo Superior de Investigaciones Cientificas-UPV, 46022 Valencia, Spain. sfelena@ibmcp.upv.es〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14684807" target="_blank"〉PubMed〈/a〉
    Keywords: *Adaptation, Physiological ; Animals ; *Biological Evolution ; Chlamydomonas/physiology ; Darkness ; *Ecosystem ; Environment ; *Genetic Variation ; Genotype ; Light ; Mutation ; Phenotype ; Pseudomonas fluorescens/genetics/*physiology ; RNA Viruses/physiology ; Selection, Genetic
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  • 67
    Publication Date: 2003-09-13
    Description: During spliceosome activation, a large structural rearrangement occurs that involves the release of two small nuclear RNAs, U1 and U4, and the addition of a protein complex associated with Prp19p. We show here that the Prp19p-associated complex is required for stable association of U5 and U6 with the spliceosome after U4 is dissociated. Ultraviolet crosslinking analysis revealed the existence of two modes of base pairing between U6 and the 5' splice site, as well as a switch of such base pairing from one to the other that required the Prp19p-associated complex during spliceosome activation. Moreover, a Prp19p-dependent structural change in U6 small nuclear ribonucleoprotein particles was detected that involves destabilization of Sm-like (Lsm) proteins to bring about interactions between the Lsm binding site of U6 and the intron sequence near the 5' splice site, indicating dynamic association of Lsm with U6 and a direct role of Lsm proteins in activation of the spliceosome.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chan, Shih-Peng -- Kao, Der-I -- Tsai, Wei-Yu -- Cheng, Soo-Chen -- New York, N.Y. -- Science. 2003 Oct 10;302(5643):279-82. Epub 2003 Sep 11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Microbiology and Immunology, National Yang-Ming University, Shih-Pai, Taiwan, Republic of China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12970570" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Base Pairing ; Binding Sites ; Blotting, Northern ; Introns ; Molecular Sequence Data ; RNA Precursors/metabolism ; RNA Splicing ; RNA, Small Nuclear/metabolism ; RNA-Binding Proteins/chemistry/metabolism ; Ribonuclease H/metabolism ; Ribonucleoprotein, U4-U6 Small Nuclear/chemistry/*metabolism ; Saccharomyces cerevisiae Proteins/*metabolism ; Spliceosomes/*metabolism
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  • 68
    Publication Date: 2003-12-04
    Description: The net ecosystem exchange of carbon dioxide was measured by eddy covariance methods for 3 years in two old-growth forest sites near Santarem, Brazil. Carbon was lost in the wet season and gained in the dry season, which was opposite to the seasonal cycles of both tree growth and model predictions. The 3-year average carbon loss was 1.3 (confidence interval: 0.0 to 2.0) megagrams of carbon per hectare per year. Biometric observations confirmed the net loss but imply that it is a transient effect of recent disturbance superimposed on long-term balance. Given that episodic disturbances are characteristic of old-growth forests, it is likely that carbon sequestration is lower than has been inferred from recent eddy covariance studies at undisturbed sites.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Saleska, Scott R -- Miller, Scott D -- Matross, Daniel M -- Goulden, Michael L -- Wofsy, Steven C -- da Rocha, Humberto R -- de Camargo, Plinio B -- Crill, Patrick -- Daube, Bruce C -- de Freitas, Helber C -- Hutyra, Lucy -- Keller, Michael -- Kirchhoff, Volker -- Menton, Mary -- Munger, J William -- Pyle, Elizabeth Hammond -- Rice, Amy H -- Silva, Hudson -- New York, N.Y. -- Science. 2003 Nov 28;302(5650):1554-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA. saleska@fas.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14645845" target="_blank"〉PubMed〈/a〉
    Keywords: Brazil ; Carbon/*analysis/metabolism ; Carbon Dioxide/*analysis/metabolism ; Confidence Intervals ; *Ecosystem ; Oxygen Consumption ; Photosynthesis ; Rain ; *Seasons ; *Trees/growth & development/metabolism ; Wood
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  • 69
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-05-10
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kerr, Richard A -- New York, N.Y. -- Science. 2003 May 9;300(5621):885.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12738825" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Ascomycota ; Charcoal ; Climate ; *Ecosystem ; Feces/microbiology ; Geologic Sediments ; Humans ; Madagascar ; *Mammals ; New York ; *Paleontology ; Pollen ; Population Dynamics ; *Spores, Fungal
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  • 70
    Publication Date: 2003-01-11
    Description: In the Pacific Ocean, air and ocean temperatures, atmospheric carbon dioxide, landings of anchovies and sardines, and the productivity of coastal and open ocean ecosystems have varied over periods of about 50 years. In the mid-1970s, the Pacific changed from a cool "anchovy regime" to a warm "sardine regime." A shift back to an anchovy regime occurred in the middle to late 1990s. These large-scale, naturally occurring variations must be taken into account when considering human-induced climate change and the management of ocean living resources.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chavez, Francisco P -- Ryan, John -- Lluch-Cota, Salvador E -- Niquen C, Miguel -- New York, N.Y. -- Science. 2003 Jan 10;299(5604):217-21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039, USA. chfr@mbari.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12522241" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atmosphere ; Birds ; Carbon Dioxide ; *Climate ; *Ecosystem ; *Fishes ; Pacific Ocean ; *Seawater ; Temperature ; Time Factors
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  • 71
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-08-23
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Malakoff, David -- New York, N.Y. -- Science. 2003 Aug 22;301(5636):1034-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12933987" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Anthozoa ; Atlantic Ocean ; Conservation of Natural Resources ; *Ecosystem ; Environment ; Fisheries ; *Fishes ; Geologic Sediments ; *Marine Biology ; Pacific Ocean ; *Seawater
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  • 72
    Publication Date: 2003-07-19
    Description: We collected and completely sequenced 28,469 full-length complementary DNA clones from Oryza sativa L. ssp. japonica cv. Nipponbare. Through homology searches of publicly available sequence data, we assigned tentative protein functions to 21,596 clones (75.86%). Mapping of the cDNA clones to genomic DNA revealed that there are 19,000 to 20,500 transcription units in the rice genome. Protein informatics analysis against the InterPro database revealed the existence of proteins presented in rice but not in Arabidopsis. Sixty-four percent of our cDNAs are homologous to Arabidopsis proteins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rice Full-Length cDNA Consortium -- National Institute of Agrobiological Sciences Rice Full-Length cDNA Project Team -- Kikuchi, Shoshi -- Satoh, Kouji -- Nagata, Toshifumi -- Kawagashira, Nobuyuki -- Doi, Koji -- Kishimoto, Naoki -- Yazaki, Junshi -- Ishikawa, Masahiro -- Yamada, Hitomi -- Ooka, Hisako -- Hotta, Isamu -- Kojima, Keiichi -- Namiki, Takahiro -- Ohneda, Eisuke -- Yahagi, Wataru -- Suzuki, Kohji -- Li, Chao Jie -- Ohtsuki, Kenji -- Shishiki, Toru -- Foundation of Advancement of International Science Genome Sequencing & Analysis Group -- Otomo, Yasuhiro -- Murakami, Kazuo -- Iida, Yoshiharu -- Sugano, Sumio -- Fujimura, Tatsuto -- Suzuki, Yutaka -- Tsunoda, Yuki -- Kurosaki, Takashi -- Kodama, Takeko -- Masuda, Hiromi -- Kobayashi, Michie -- Xie, Quihong -- Lu, Min -- Narikawa, Ryuya -- Sugiyama, Akio -- Mizuno, Kouichi -- Yokomizo, Satoko -- Niikura, Junko -- Ikeda, Rieko -- Ishibiki, Junya -- Kawamata, Midori -- Yoshimura, Akemi -- Miura, Junichirou -- Kusumegi, Takahiro -- Oka, Mitsuru -- Ryu, Risa -- Ueda, Mariko -- Matsubara, Kenichi -- RIKEN -- Kawai, Jun -- Carninci, Piero -- Adachi, Jun -- Aizawa, Katsunori -- Arakawa, Takahiro -- Fukuda, Shiro -- Hara, Ayako -- Hashizume, Wataru -- Hayatsu, Norihito -- Imotani, Koichi -- Ishii, Yoshiyuki -- Itoh, Masayoshi -- Kagawa, Ikuko -- Kondo, Shinji -- Konno, Hideaki -- Miyazaki, Ai -- Osato, Naoki -- Ota, Yoshimi -- Saito, Rintaro -- Sasaki, Daisuke -- Sato, Kenjiro -- Shibata, Kazuhiro -- Shinagawa, Akira -- Shiraki, Toshiyuki -- Yoshino, Masayasu -- Hayashizaki, Yoshihide -- Yasunishi, Ayako -- New York, N.Y. -- Science. 2003 Jul 18;301(5631):376-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, National Institute of Agrobiological Sciences, 2-1-2 Kannon-dai, Tsukuba, Ibaraki 305-8602, Japan. skikuchi@nias.affrc.go.jp〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12869764" target="_blank"〉PubMed〈/a〉
    Keywords: Alternative Splicing ; Amino Acid Sequence ; Cloning, Molecular ; Computational Biology ; DNA, Complementary ; Databases, Nucleic Acid ; Databases, Protein ; Genes, Plant ; *Genome, Plant ; Molecular Sequence Data ; Open Reading Frames ; Oryza/*genetics ; Plant Proteins/chemistry/genetics/physiology ; Protein Structure, Tertiary ; RNA, Antisense/genetics ; *Sequence Analysis, DNA ; Sequence Homology, Amino Acid ; Sequence Homology, Nucleic Acid ; Transcription Factors/chemistry/genetics ; Transcription, Genetic
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  • 73
    Publication Date: 2003-09-06
    Description: The finding that microbial communities are active under snow has changed the estimated global rates of biogeochemical processes beneath seasonal snow packs. We used microbiological and molecular techniques to elucidate the phylogenetic composition of undersnow microbial communities in Colorado, the United States. Here, we show that tundra soil microbial biomass reaches its annual peak under snow, and that fungi account for most of the biomass. Phylogenetic analysis of tundra soil fungi revealed a high diversity of fungi and three novel clades that constitute major new groups of fungi (divergent at the subphylum or class level). An abundance of previously unknown fungi that are active beneath the snow substantially broadens our understanding of both the diversity and biogeochemical functioning of fungi in cold environments.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schadt, Christopher W -- Martin, Andrew P -- Lipson, David A -- Schmidt, Steven K -- New York, N.Y. -- Science. 2003 Sep 5;301(5638):1359-61.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12958355" target="_blank"〉PubMed〈/a〉
    Keywords: Ascomycota/classification/genetics/growth & development/isolation & purification ; Basidiomycota/classification/genetics/growth & development/isolation & ; purification ; Bayes Theorem ; Biomass ; *Cold Climate ; Colorado ; DNA, Fungal/analysis/genetics ; *Ecosystem ; Fungi/*classification/genetics/*growth & development/isolation & purification ; Phylogeny ; *Seasons ; Snow ; *Soil Microbiology
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  • 74
    Publication Date: 2003-06-21
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chick, John H -- Maher, Robert J -- Burr, Brooks M -- Thomas, Matthew R -- New York, N.Y. -- Science. 2003 Jun 20;300(5627):1876-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12817125" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Aquaculture ; Bivalvia ; *Carps/classification ; Conservation of Natural Resources ; *Ecosystem ; Fresh Water ; Illinois
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  • 75
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-03-29
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Swart, Jac A A -- New York, N.Y. -- Science. 2003 Mar 28;299(5615):1981-2; author reply 1981-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12663896" target="_blank"〉PubMed〈/a〉
    Keywords: Conservation of Natural Resources/*economics ; Cost-Benefit Analysis ; *Ecosystem ; Financial Management
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  • 76
    Publication Date: 2003-09-27
    Description: A survey of the dog genome sequence (6.22 million sequence reads; 1.5x coverage) demonstrates the power of sample sequencing for comparative analysis of mammalian genomes and the generation of species-specific resources. More than 650 million base pairs (〉25%) of dog sequence align uniquely to the human genome, including fragments of putative orthologs for 18,473 of 24,567 annotated human genes. Mutation rates, conserved synteny, repeat content, and phylogeny can be compared among human, mouse, and dog. A variety of polymorphic elements are identified that will be valuable for mapping the genetic basis of diseases and traits in the dog.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kirkness, Ewen F -- Bafna, Vineet -- Halpern, Aaron L -- Levy, Samuel -- Remington, Karin -- Rusch, Douglas B -- Delcher, Arthur L -- Pop, Mihai -- Wang, Wei -- Fraser, Claire M -- Venter, J Craig -- New York, N.Y. -- Science. 2003 Sep 26;301(5641):1898-903.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Institute for Genomic Research, Rockville, MD 20850, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14512627" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Chromosomes, Mammalian/genetics ; Computational Biology ; Conserved Sequence ; Contig Mapping ; DNA, Intergenic ; Dogs/*genetics ; Genetic Variation ; *Genome ; Genome, Human ; Genomics ; Humans ; Long Interspersed Nucleotide Elements ; Male ; Mice/genetics ; Molecular Sequence Data ; Mutation ; Phylogeny ; Physical Chromosome Mapping ; Polymorphism, Single Nucleotide ; RNA, Messenger/genetics ; Repetitive Sequences, Nucleic Acid ; Sequence Alignment ; *Sequence Analysis, DNA ; Short Interspersed Nucleotide Elements ; Synteny
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  • 77
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2003-10-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chivian, Eric -- Roberts, Callum M -- Bernstein, Aaron S -- New York, N.Y. -- Science. 2003 Oct 17;302(5644):391.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14563988" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Anthozoa ; Biomedical Research ; Conotoxins ; *Conservation of Natural Resources ; *Ecosystem ; Environment ; *Snails
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  • 78
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-03-28
    Description: The metabotropic glutamate receptors (mGluRs) are widely distributed in the brain and play important roles in synaptic plasticity. Here it is shown that some types of mGluRs are activated not only by glutamate but also by extracellular Ca2+ (Ca2+o). A single amino acid residue was found to determine the sensitivity of mGluRs to Ca2+o. One of the receptors, mGluR1alpha, but not its point mutant with reduced sensitivity to Ca2+o, caused morphological changes when transfected into mammalian cells. Thus, the sensing of Ca2+o by mGluRs may be important in cells under physiological condition.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kubo, Y -- Miyashita, T -- Murata, Y -- New York, N.Y. -- Science. 1998 Mar 13;279(5357):1722-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neurophysiology, Tokyo Metropolitan Institute for Neuroscience, Musashidai 2-6, Fuchu, Tokyo 183-8526, Japan. ykubo@tmin.ac.jp〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9497291" target="_blank"〉PubMed〈/a〉
    Keywords: Actins/ultrastructure ; Amino Acid Sequence ; Animals ; Binding Sites ; Brain/metabolism ; CHO Cells ; Calcium/*metabolism/pharmacology ; Cell Size ; Cricetinae ; Cyclic AMP/metabolism ; G Protein-Coupled Inwardly-Rectifying Potassium Channels ; Glutamic Acid/metabolism/pharmacology ; Molecular Sequence Data ; Oocytes ; Point Mutation ; Potassium Channels/metabolism ; *Potassium Channels, Inwardly Rectifying ; Rats ; Receptors, Metabotropic Glutamate/chemistry/genetics/*metabolism ; Recombinant Fusion Proteins/metabolism ; Second Messenger Systems ; Transfection ; Xenopus laevis
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  • 79
    Publication Date: 1998-12-16
    Description: A peripheral membrane protein that is interactive with lymphocytic choriomeningitis virus (LCMV) was purified from cells permissive to infection. Tryptic peptides from this protein were determined to be alpha-dystroglycan (alpha-DG). Several strains of LCMV and other arenaviruses, including Lassa fever virus (LFV), Oliveros, and Mobala, bound to purified alpha-DG protein. Soluble alpha-DG blocked both LCMV and LFV infection. Cells bearing a null mutation of the gene encoding DG were resistant to LCMV infection, and reconstitution of DG expression in null mutant cells restored susceptibility to LCMV infection. Thus, alpha-DG is a cellular receptor for both LCMV and LFV.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cao, W -- Henry, M D -- Borrow, P -- Yamada, H -- Elder, J H -- Ravkov, E V -- Nichol, S T -- Compans, R W -- Campbell, K P -- Oldstone, M B -- AG 00080/AG/NIA NIH HHS/ -- AI 09484/AI/NIAID NIH HHS/ -- DK09712/DK/NIDDK NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1998 Dec 11;282(5396):2079-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Virology, Department of Neuropharmacology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9851928" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Arenavirus/metabolism ; Cell Line ; Cytoskeletal Proteins/chemistry/genetics/*metabolism ; Dystroglycans ; Lassa virus/*metabolism/physiology ; Lymphocytic choriomeningitis virus/*metabolism/physiology ; Membrane Glycoproteins/chemistry/genetics/*metabolism ; Mice ; Molecular Sequence Data ; Mutation ; Receptors, Virus/chemistry/*metabolism ; Recombinant Fusion Proteins/metabolism ; Virus Replication
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  • 80
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-04-29
    Description: After the vertebrate lens is induced from head ectoderm, lens-specific genes are expressed. Transcriptional regulation of the lens-specific alphaA-crystallin gene is controlled by an enhancer element, alphaCE2. A gene encoding an alphaCE2-binding protein, L-maf(lens-specific maf), was isolated. L-maf expression is initiated in the lens placode and is restricted to lens cells. The gene product L-Maf regulates the expression of multiple genes expressed in the lens, and ectopic expression of this transcription factor converts chick embryonic ectodermal cells and cultured cells into lens fibers. Thus, vertebrate lens induction and differentiation can be triggered by the activation of L-Maf.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ogino, H -- Yasuda, K -- New York, N.Y. -- Science. 1998 Apr 3;280(5360):115-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0101, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9525857" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Basic-Leucine Zipper Transcription Factors ; Cell Differentiation ; Cells, Cultured ; Chick Embryo ; Crystallins/genetics ; DNA, Complementary ; DNA-Binding Proteins/chemistry/genetics ; Ectoderm ; Enhancer Elements, Genetic ; Eye Proteins/genetics ; G-Box Binding Factors ; *Gene Expression Regulation, Developmental ; Genes, Reporter ; Intermediate Filament Proteins/genetics ; Lens, Crystalline/*cytology/*embryology/metabolism ; Maf Transcription Factors ; Molecular Sequence Data ; Promoter Regions, Genetic ; Recombinant Fusion Proteins/metabolism ; Transcription Factors/chemistry/genetics/*metabolism ; *Transcription, Genetic ; Transcriptional Activation ; Transfection
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  • 81
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-03-21
    Description: Mice homozygous for a disrupted allele of the mismatch repair gene Pms2 have a mutator phenotype. When this allele is crossed into quasi-monoclonal (QM) mice, which have a very limited B cell repertoire, homozygotes have fewer somatic mutations at the immunoglobulin heavy chain and lambda chain loci than do heterozygotes or wild-type QM mice. That is, mismatch repair seems to contribute to somatic hypermutation rather than stifling it. It is suggested that at immunoglobulin loci in hypermutable B cells, mismatched base pairs are "corrected" according to the newly synthesized DNA strand, thereby fixing incipient mutations instead of eliminating them.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cascalho, M -- Wong, J -- Steinberg, C -- Wabl, M -- 1R01 GM37699/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 Feb 20;279(5354):1207-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology, University of California, San Francisco, CA 94143-0670, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9469811" target="_blank"〉PubMed〈/a〉
    Keywords: *Adenosine Triphosphatases ; Alleles ; Amino Acid Sequence ; Animals ; B-Lymphocytes/immunology ; Base Composition ; Base Sequence ; Cloning, Molecular ; Crosses, Genetic ; *DNA Repair ; *DNA Repair Enzymes ; *DNA-Binding Proteins ; Female ; Gene Rearrangement ; *Genes, Immunoglobulin ; Heterozygote ; Immunoglobulin Heavy Chains/chemistry/genetics ; Immunoglobulin Variable Region/chemistry/*genetics ; Immunoglobulin lambda-Chains/chemistry/genetics ; Male ; Mice ; Mice, Knockout ; Molecular Sequence Data ; *Mutation ; Proteins/*genetics/physiology
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  • 82
    Publication Date: 1998-12-05
    Description: Group I introns possess a single active site that catalyzes the two sequential reactions of self-splicing. An RNA comprising the two domains of the Tetrahymena thermophila group I intron catalytic core retains activity, and the 5.0 angstrom crystal structure of this 247-nucleotide ribozyme is now described. Close packing of the two domains forms a shallow cleft capable of binding the short helix that contains the 5' splice site. The helix that provides the binding site for the guanosine substrate deviates significantly from A-form geometry, providing a tight binding pocket. The binding pockets for both the 5' splice site helix and guanosine are formed and oriented in the absence of these substrates. Thus, this large ribozyme is largely preorganized for catalysis, much like a globular protein enzyme.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Golden, B L -- Gooding, A R -- Podell, E R -- Cech, T R -- New York, N.Y. -- Science. 1998 Oct 9;282(5387):259-64.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA. bgolden@petunia.colorado.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9841391" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Pairing ; Base Sequence ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; Guanosine/metabolism ; Introns ; Magnesium/metabolism ; Manganese/metabolism ; *Models, Molecular ; Molecular Sequence Data ; *Nucleic Acid Conformation ; Phosphates/metabolism ; RNA Splicing ; RNA, Catalytic/*chemistry/metabolism ; Tetrahymena thermophila/*genetics
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  • 83
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-07-10
    Description: The 2.5 angstrom resolution x-ray crystal structure of the Escherichia coli RNA polymerase (RNAP) alpha subunit amino-terminal domain (alphaNTD), which is necessary and sufficient to dimerize and assemble the other RNAP subunits into a transcriptionally active enzyme and contains all of the sequence elements conserved among eukaryotic alpha homologs, has been determined. The alphaNTD monomer comprises two distinct, flexibly linked domains, only one of which participates in the dimer interface. In the alphaNTD dimer, a pair of helices from one monomer interact with the cognate helices of the other to form an extensive hydrophobic core. All of the determinants for interactions with the other RNAP subunits lie on one face of the alphaNTD dimer. Sequence alignments, combined with secondary-structure predictions, support proposals that a heterodimer of the eukaryotic RNAP subunits related to Saccharomyces cerevisiae Rpb3 and Rpb11 plays the role of the alphaNTD dimer in prokaryotic RNAP.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhang, G -- Darst, S A -- GM19441-01/GM/NIGMS NIH HHS/ -- GM53759/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 Jul 10;281(5374):262-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9657722" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Crystallography, X-Ray ; DNA-Directed RNA Polymerases/*chemistry ; Dimerization ; Escherichia coli/*enzymology ; Models, Molecular ; Molecular Sequence Data ; *Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; RNA Polymerase II/chemistry ; *Saccharomyces cerevisiae Proteins ; Sequence Alignment
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  • 84
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-02-07
    Description: The development of plant root systems is sensitive to the availability and distribution of nutrients within the soil. For example, lateral roots proliferate preferentially within nitrate (NO3-)-rich soil patches. A NO3--inducible Arabidopsis gene (ANR1), was identified that encodes a member of the MADS box family of transcription factors. Transgenic plants in which ANR1 was repressed had an altered sensitivity to NO3- and no longer responded to NO3--rich zones by lateral root proliferation, indicating that ANR1 is a key determinant of developmental plasticity in Arabidopsis roots.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhang, H -- Forde, B G -- New York, N.Y. -- Science. 1998 Jan 16;279(5349):407-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biochemistry and Physiology Department, IACR-Rothamsted, Harpenden, Herts AL5 2JQ, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9430595" target="_blank"〉PubMed〈/a〉
    Keywords: Arabidopsis/*genetics/growth & development/metabolism ; *Arabidopsis Proteins ; DNA-Binding Proteins/*genetics/physiology ; Gene Expression Regulation, Plant ; *Genes, Plant ; MADS Domain Proteins ; Molecular Sequence Data ; Nitrates/metabolism/*pharmacology ; Plant Proteins/*genetics/physiology ; Plant Roots/genetics/*growth & development/metabolism ; Plants, Genetically Modified ; Transcription Factors/*genetics/physiology
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  • 85
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-08-07
    Description: The red clover necrotic mosaic virus genome is composed of two single-stranded RNA components, RNA-1 and RNA-2. The viral capsid protein is translated from a subgenomic RNA (sgRNA) that is transcribed from genomic RNA-1. Here, a 34-nucleotide sequence in RNA-2 is shown to be required for transcription of sgRNA. Mutations that prevent base-pairing between the RNA-1 subgenomic promoter and the 34-nucleotide trans-activator prevent expression of a reporter gene. A model is proposed in which direct binding of RNA-2 to RNA-1 trans-activates sgRNA synthesis. This RNA-mediated regulation of transcription is unusual among RNA viruses, which typically rely on protein regulators.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sit, T L -- Vaewhongs, A A -- Lommel, S A -- New York, N.Y. -- Science. 1998 Aug 7;281(5378):829-32.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695-7616, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9694655" target="_blank"〉PubMed〈/a〉
    Keywords: Base Composition ; Base Sequence ; DNA, Complementary ; Gene Expression ; Genes, Reporter ; Green Fluorescent Proteins ; Luminescent Proteins/genetics ; Models, Genetic ; Molecular Sequence Data ; Mosaic Viruses/*genetics ; Mutation ; Nucleic Acid Conformation ; Promoter Regions, Genetic ; RNA, Double-Stranded/genetics/metabolism ; RNA, Messenger/biosynthesis/genetics ; RNA, Viral/biosynthesis/chemistry/*genetics ; Sequence Alignment ; *Transcriptional Activation
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  • 86
    Publication Date: 1998-02-21
    Description: Protein kinase B (PKB) is activated in response to phosphoinositide 3-kinases and their lipid products phosphatidylinositol 3,4, 5-trisphosphate [PtdIns(3,4,5)P3] and PtdIns(3,4)P2 in the signaling pathways used by a wide variety of growth factors, antigens, and inflammatory stimuli. PKB is a direct target of these lipids, but this regulation is complex. The lipids can bind to the pleckstrin homologous domain of PKB, causing its translocation to the membrane, and also enable upstream, Thr308-directed kinases to phosphorylate and activate PKB. Four isoforms of these PKB kinases were purified from sheep brain. They bound PtdIns(3,4,5)P3 and associated with lipid vesicles containing it. These kinases contain an NH2-terminal catalytic domain and a COOH-terminal pleckstrin homologous domain, and their heterologous expression augments receptor activation of PKB, which suggests they are the primary signal transducers that enable PtdIns(3,4,5)P3 or PtdIns- (3,4)P2 to activate PKB and hence to control signaling pathways regulating cell survival, glucose uptake, and glycogen metabolism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stephens, L -- Anderson, K -- Stokoe, D -- Erdjument-Bromage, H -- Painter, G F -- Holmes, A B -- Gaffney, P R -- Reese, C B -- McCormick, F -- Tempst, P -- Coadwell, J -- Hawkins, P T -- Wellcome Trust/United Kingdom -- New York, N.Y. -- Science. 1998 Jan 30;279(5351):710-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Inositide Laboratory, The Babraham Institute, Babraham, Cambridge CB2 4AT, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9445477" target="_blank"〉PubMed〈/a〉
    Keywords: 3-Phosphoinositide-Dependent Protein Kinases ; Alternative Splicing ; Amino Acid Sequence ; Animals ; Cell Line ; Cell Membrane/enzymology ; Cloning, Molecular ; DNA, Complementary ; Drosophila ; Drosophila Proteins ; Enzyme Activation ; Humans ; Liposomes/metabolism ; Molecular Sequence Data ; Open Reading Frames ; Phosphatidylinositol Phosphates/*metabolism ; Phosphorylation ; Platelet-Derived Growth Factor/pharmacology ; Protein-Serine-Threonine Kinases/chemistry/genetics/isolation & ; purification/*metabolism ; Proto-Oncogene Proteins/*metabolism ; Proto-Oncogene Proteins c-akt ; Rats ; Recombinant Proteins/metabolism ; Sheep ; *Signal Transduction
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  • 87
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-08-15
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ginsberg, H S -- Hyland, D E -- Hu, R -- New York, N.Y. -- Science. 1998 Jul 17;281(5375):349-50.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9705710" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Ecosystem ; Forestry ; Ixodes/*physiology ; New York ; Nymph/physiology ; Population Dynamics ; Rhode Island ; *Trees
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  • 88
    Publication Date: 1998-03-21
    Description: Viral infection is sometimes associated with the initiation or exacerbation of autoimmune disease, although the underlying mechanisms remain unclear. One proposed mechanism is that viral determinants that mimic host antigens trigger self-reactive T cell clones to destroy host tissue. An epitope expressed by a coat protein of herpes simplex virus-type 1 (HSV-1) KOS strain has now been shown to be recognized by autoreactive T cells that target corneal antigens in a murine model of autoimmune herpes stromal keratitis. Mutant HSV-1 viruses that lacked this epitope did not induce autoimmune disease. Thus, expression of molecular mimics can influence the development of autoimmune disease after viral infection.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhao, Z S -- Granucci, F -- Yeh, L -- Schaffer, P A -- Cantor, H -- AI 37562/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1998 Feb 27;279(5355):1344-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Harvard Medical School, and Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, MA 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9478893" target="_blank"〉PubMed〈/a〉
    Keywords: Adoptive Transfer ; Amino Acid Sequence ; Animals ; Autoantigens/immunology ; Autoimmune Diseases/*immunology ; CD4-Positive T-Lymphocytes/immunology ; Capsid/chemistry/genetics/*immunology ; *Capsid Proteins ; Cornea/*immunology ; Epitopes ; Eye Proteins/immunology ; Herpesvirus 1, Human/*immunology ; Keratitis, Herpetic/*immunology ; Lymphocyte Activation ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Mice, SCID ; *Molecular Mimicry ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Oligopeptides/immunology ; Viral Proteins
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  • 89
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-03-28
    Description: The OxyR transcription factor is sensitive to oxidation and activates the expression of antioxidant genes in response to hydrogen peroxide in Escherichia coli. Genetic and biochemical studies revealed that OxyR is activated through the formation of a disulfide bond and is deactivated by enzymatic reduction with glutaredoxin 1 (Grx1). The gene encoding Grx1 is regulated by OxyR, thus providing a mechanism for autoregulation. The redox potential of OxyR was determined to be -185 millivolts, ensuring that OxyR is reduced in the absence of stress. These results represent an example of redox signaling through disulfide bond formation and reduction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zheng, M -- Aslund, F -- Storz, G -- New York, N.Y. -- Science. 1998 Mar 13;279(5357):1718-21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9497290" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Amino Acid Substitution ; Bacterial Proteins/genetics/metabolism ; Base Sequence ; Cysteine/metabolism ; *DNA-Binding Proteins ; Disulfides/*metabolism ; Escherichia coli/genetics/*metabolism ; Escherichia coli Proteins ; Gene Expression Regulation, Bacterial ; Glutaredoxins ; Glutathione/metabolism ; Glutathione Disulfide/metabolism ; Glutathione Reductase/metabolism ; Hydrogen Peroxide/*metabolism/pharmacology ; Molecular Sequence Data ; Oxidation-Reduction ; Oxidative Stress ; *Oxidoreductases ; Proteins/genetics/metabolism ; Repressor Proteins/genetics/*metabolism ; Signal Transduction ; Thioredoxins/metabolism ; Transcription Factors/genetics/*metabolism
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  • 90
    Publication Date: 1998-10-23
    Description: Analysis of the 1,042,519-base pair Chlamydia trachomatis genome revealed unexpected features related to the complex biology of chlamydiae. Although chlamydiae lack many biosynthetic capabilities, they retain functions for performing key steps and interconversions of metabolites obtained from their mammalian host cells. Numerous potential virulence-associated proteins also were characterized. Several eukaryotic chromatin-associated domain proteins were identified, suggesting a eukaryotic-like mechanism for chlamydial nucleoid condensation and decondensation. The phylogenetic mosaic of chlamydial genes, including a large number of genes with phylogenetic origins from eukaryotes, implies a complex evolution for adaptation to obligate intracellular parasitism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stephens, R S -- Kalman, S -- Lammel, C -- Fan, J -- Marathe, R -- Aravind, L -- Mitchell, W -- Olinger, L -- Tatusov, R L -- Zhao, Q -- Koonin, E V -- Davis, R W -- AI 39258/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1998 Oct 23;282(5389):754-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Program in Infectious Diseases, University of California, Berkeley, CA 94720, USA. ctgenome@socrates.berkeley.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9784136" target="_blank"〉PubMed〈/a〉
    Keywords: Aerobiosis ; Amino Acid Sequence ; Amino Acids/biosynthesis ; Bacterial Outer Membrane Proteins/genetics ; Bacterial Proteins/chemistry/genetics ; Biological Evolution ; Chlamydia trachomatis/classification/*genetics/metabolism/physiology ; DNA Repair ; Energy Metabolism ; Enzymes/chemistry/genetics ; *Genome, Bacterial ; Humans ; Lipids/biosynthesis ; Molecular Sequence Data ; Peptidoglycan/biosynthesis/genetics ; Phylogeny ; Protein Biosynthesis ; Recombination, Genetic ; *Sequence Analysis, DNA ; Transcription, Genetic ; Transformation, Bacterial ; Virulence
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  • 91
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-07-10
    Description: Recombinant proteins containing four cysteines at the i, i + 1, i + 4, and i + 5 positions of an alpha helix were fluorescently labeled in living cells by extracellular administration of 4',5'-bis(1,3, 2-dithioarsolan-2-yl)fluorescein. This designed small ligand is membrane-permeant and nonfluorescent until it binds with high affinity and specificity to the tetracysteine domain. Such in situ labeling adds much less mass than does green fluorescent protein and offers greater versatility in attachment sites as well as potential spectroscopic and chemical properties. This system provides a recipe for slightly modifying a target protein so that it can be singled out from the many other proteins inside live cells and fluorescently stained by small nonfluorescent dye molecules added from outside the cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Griffin, B A -- Adams, S R -- Tsien, R Y -- NS27177/NS/NINDS NIH HHS/ -- T32 CA09523/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1998 Jul 10;281(5374):269-72.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093-0647, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9657724" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Calmodulin/chemistry/genetics/metabolism ; Cell Membrane Permeability ; Cell Survival ; Cysteine/*chemistry ; Energy Transfer ; Ethylene Glycol ; Fluoresceins/chemical synthesis/chemistry/*metabolism ; Fluorescence ; *Fluorescent Dyes ; Green Fluorescent Proteins ; HeLa Cells ; Humans ; Jurkat Cells ; Ligands ; Luminescent Proteins/chemistry/genetics/metabolism ; Molecular Sequence Data ; Organometallic Compounds/chemical synthesis/chemistry/*metabolism ; Peptides/chemistry/*metabolism ; Protein Structure, Secondary ; Recombinant Proteins/chemistry/*metabolism ; Spectrometry, Fluorescence ; Transfection
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  • 92
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-03-21
    Description: The three-dimensional structure of a 70-kilodalton amino terminally truncated form of human topoisomerase I in complex with a 22-base pair duplex oligonucleotide, determined to a resolution of 2.8 angstroms, reveals all of the structural elements of the enzyme that contact DNA. The linker region that connects the central core of the enzyme to the carboxyl-terminal domain assumes a coiled-coil configuration and protrudes away from the remainder of the enzyme. The positively charged DNA-proximal surface of the linker makes only a few contacts with the DNA downstream of the cleavage site. In combination with the crystal structures of the reconstituted human topoisomerase I before and after DNA cleavage, this information suggests which amino acid residues are involved in catalyzing phosphodiester bond breakage and religation. The structures also lead to the proposal that the topoisomerization step occurs by a mechanism termed "controlled rotation."〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stewart, L -- Redinbo, M R -- Qiu, X -- Hol, W G -- Champoux, J J -- CA65656/CA/NCI NIH HHS/ -- GM16713/GM/NIGMS NIH HHS/ -- GM49156/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 Mar 6;279(5356):1534-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biomolecular Structure Center and Department of Biological Structure, School of Medicine, University of Washington, Seattle, WA 98195-7742, USA. emerald_biostructures@rocketmail.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9488652" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Arginine/chemistry/metabolism ; Binding Sites ; Catalysis ; Crystallography, X-Ray ; DNA/chemistry/*metabolism ; DNA Topoisomerases, Type I/*chemistry/*metabolism ; Humans ; Hydrogen Bonding ; *Models, Chemical ; Models, Molecular ; Molecular Sequence Data ; Nucleic Acid Conformation ; Oligodeoxyribonucleotides/chemistry/metabolism ; *Protein Conformation ; Protein Structure, Secondary ; Tyrosine/chemistry/metabolism
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  • 93
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-03-21
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pennisi, E -- New York, N.Y. -- Science. 1998 Mar 6;279(5356):1445.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9508717" target="_blank"〉PubMed〈/a〉
    Keywords: Biotechnology ; Brazil ; *Ecosystem ; Ownership/economics/*legislation & jurisprudence
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  • 94
    Publication Date: 1998-11-13
    Description: The ectodomains of numerous proteins are released from cells by proteolysis to yield soluble intercellular regulators. The responsible protease, tumor necrosis factor-alpha converting enzyme (TACE), has been identified only in the case when tumor necrosis factor-alpha (TNFalpha) is released. Analyses of cells lacking this metalloproteinase-disintegrin revealed an expanded role for TACE in the processing of other cell surface proteins, including a TNF receptor, the L-selectin adhesion molecule, and transforming growth factor-alpha (TGFalpha). The phenotype of mice lacking TACE suggests an essential role for soluble TGFalpha in normal development and emphasizes the importance of protein ectodomain shedding in vivo.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Peschon, J J -- Slack, J L -- Reddy, P -- Stocking, K L -- Sunnarborg, S W -- Lee, D C -- Russell, W E -- Castner, B J -- Johnson, R S -- Fitzner, J N -- Boyce, R W -- Nelson, N -- Kozlosky, C J -- Wolfson, M F -- Rauch, C T -- Cerretti, D P -- Paxton, R J -- March, C J -- Black, R A -- CA43793/CA/NCI NIH HHS/ -- DK53804/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1998 Nov 13;282(5392):1281-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Immunex Corporation, Seattle, WA 98101, USA. peschon@immunex.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9812885" target="_blank"〉PubMed〈/a〉
    Keywords: ADAM Proteins ; Amino Acid Sequence ; Animals ; Catalytic Domain ; Cell Membrane/*metabolism ; Cells, Cultured ; Crosses, Genetic ; *Embryonic and Fetal Development ; L-Selectin/metabolism ; Ligands ; Membrane Proteins/*metabolism ; Metalloendopeptidases/chemistry/genetics/*metabolism ; Mice ; Mice, Inbred C57BL ; Molecular Sequence Data ; Mutation ; Phenotype ; Protein Processing, Post-Translational ; Receptors, Tumor Necrosis Factor/metabolism ; Transforming Growth Factor alpha/metabolism ; Tumor Necrosis Factor-alpha/*metabolism
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  • 95
    Publication Date: 1998-03-21
    Description: Long-term potentiation (LTP) is an activity-dependent strengthening of synaptic efficacy that is considered to be a model of learning and memory. Protein tyrosine phosphorylation is necessary to induce LTP. Here, induction of LTP in CA1 pyramidal cells of rats was prevented by blocking the tyrosine kinase Src, and Src activity was increased by stimulation producing LTP. Directly activating Src in the postsynaptic neuron enhanced excitatory synaptic responses, occluding LTP. Src-induced enhancement of alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA) receptor-mediated synaptic responses required raised intracellular Ca2+ and N-methyl-D-aspartate (NMDA) receptors. Thus, Src activation is necessary and sufficient for inducing LTP and may function by up-regulating NMDA receptors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lu, Y M -- Roder, J C -- Davidow, J -- Salter, M W -- New York, N.Y. -- Science. 1998 Feb 27;279(5355):1363-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Samuel Lunenfeld Research Institute, Mount Sinai Hospital, and Department of Molecular and Medical Genetics, University of Toronto, M5S 1A8, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9478899" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Calcium/metabolism ; Electric Stimulation ; Enzyme Activation ; Excitatory Postsynaptic Potentials/drug effects ; Hippocampus/cytology/enzymology/*physiology ; In Vitro Techniques ; *Long-Term Potentiation ; Molecular Sequence Data ; Oligopeptides/pharmacology ; Patch-Clamp Techniques ; Peptide Fragments/pharmacology ; Proto-Oncogene Proteins pp60(c-src)/pharmacology ; Pyramidal Cells/enzymology/*physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, AMPA/physiology ; Receptors, N-Methyl-D-Aspartate/physiology ; Recombinant Proteins/pharmacology ; Up-Regulation ; src-Family Kinases/*metabolism
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  • 96
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-04-16
    Description: Genetic selection was exploited in combination with structure-based design to transform an intimately entwined, dimeric chorismate mutase into a monomeric, four-helix-bundle protein with near native activity. Successful reengineering depended on choosing a thermostable starting protein, introducing point mutations that preferentially destabilize the wild-type dimer, and using directed evolution to optimize an inserted interhelical turn. Contrary to expectations based on studies of other four-helix-bundle proteins, only a small fraction of possible turn sequences (fewer than 0.05 percent) yielded well-behaved, monomeric, and highly active enzymes. Selection for catalytic function thus provides an efficient yet stringent method for rapidly assessing correctly folded polypeptides and may prove generally useful for protein design.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉MacBeath, G -- Kast, P -- Hilvert, D -- New York, N.Y. -- Science. 1998 Mar 20;279(5358):1958-61.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Scripps Research Institute, Department of Chemistry, 10550 North Torrey Pines Road, La Jolla, California, 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9506949" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Catalysis ; Chorismate Mutase/*chemistry/genetics/*metabolism ; Circular Dichroism ; Cloning, Molecular ; Dimerization ; *Directed Molecular Evolution ; Escherichia coli/genetics ; Models, Molecular ; Molecular Sequence Data ; *Protein Conformation ; *Protein Engineering ; Protein Folding ; Protein Structure, Secondary ; Recombinant Proteins/chemistry/metabolism ; Transformation, Bacterial
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 97
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1998-07-31
    Description: Gamete interactions during fertilization exhibit species specificity. In abalone, the sperm protein lysin species-specifically creates a hole in the egg envelope. Lysin evolves rapidly by positive Darwinian selection. Evolution of the egg receptor for lysin provides the selective pressure for lysin's divergence. The egg receptor for lysin is a tandemly repeated sequence that evolves by concerted evolution. Concerted evolution in the egg receptor could explain the rapid, adaptive evolution in sperm lysin and may provide an underlying molecular mechanism that gives rise to species-specific fertilization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Swanson, W J -- Vacquier, V D -- HD12986/HD/NICHD NIH HHS/ -- New York, N.Y. -- Science. 1998 Jul 31;281(5377):710-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093-0202, USA. jwswanson@ucsd.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9685267" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Egg Proteins/chemistry/*genetics/metabolism ; *Evolution, Molecular ; Female ; Introns ; Male ; Molecular Sequence Data ; Mollusca/chemistry/*genetics/physiology ; Mucoproteins/chemistry/genetics/*metabolism ; Ovum/chemistry/physiology ; Receptors, Cell Surface/chemistry/*genetics/metabolism ; Repetitive Sequences, Nucleic Acid ; Selection, Genetic ; Sequence Alignment ; Species Specificity ; Sperm-Ovum Interactions ; Spermatozoa/chemistry/physiology ; Vitelline Membrane/*chemistry/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 98
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-07-17
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Appenzeller, T -- New York, N.Y. -- Science. 1999 Jun 25;284(5423):2108-10.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10409068" target="_blank"〉PubMed〈/a〉
    Keywords: *Adaptation, Physiological ; *Biological Evolution ; Culture Media ; *Ecosystem ; Escherichia coli/*genetics/physiology ; Glucose/metabolism ; Maltose/metabolism ; *Mutation ; Pseudomonas fluorescens/*genetics/physiology ; Selection, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 99
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-04-09
    Description: A "switch" mutant of the Arc repressor homodimer was constructed by interchanging the sequence positions of a hydrophobic core residue, leucine 12, and an adjacent surface polar residue, asparagine 11, in each strand of an intersubunit beta sheet. The mutant protein adopts a fold in which each beta strand is replaced by a right-handed helix and side chains in this region undergo significant repacking. The observed structural changes allow the protein to maintain solvent exposure of polar side chains and optimal burial of hydrophobic side chains. These results suggest that new protein folds can evolve from existing folds without drastic or large-scale mutagenesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cordes, M H -- Walsh, N P -- McKnight, C J -- Sauer, R T -- AI-15706/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1999 Apr 9;284(5412):325-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10195898" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Amino Acid Substitution ; Asparagine/chemistry ; Circular Dichroism ; Hydrogen Bonding ; Leucine/chemistry ; Models, Molecular ; Molecular Sequence Data ; Mutagenesis, Insertional ; Nuclear Magnetic Resonance, Biomolecular ; Protein Conformation ; *Protein Folding ; *Protein Structure, Secondary ; Protein Structure, Tertiary ; Repressor Proteins/*chemistry ; Viral Proteins/*chemistry ; Viral Regulatory and Accessory Proteins
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 100
    Publication Date: 1999-09-25
    Description: The flow of information from calcium-mobilizing receptors to nuclear factor of activated T cells (NFAT)-dependent genes is critically dependent on interaction between the phosphatase calcineurin and the transcription factor NFAT. A high-affinity calcineurin-binding peptide was selected from combinatorial peptide libraries based on the calcineurin docking motif of NFAT. This peptide potently inhibited NFAT activation and NFAT-dependent expression of endogenous cytokine genes in T cells, without affecting the expression of other cytokines that require calcineurin but not NFAT. Substitution of the optimized peptide sequence into the natural calcineurin docking site increased the calcineurin responsiveness of NFAT. Compounds that interfere selectively with the calcineurin-NFAT interaction without affecting calcineurin phosphatase activity may be useful as therapeutic agents that are less toxic than current drugs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Aramburu, J -- Yaffe, M B -- Lopez-Rodriguez, C -- Cantley, L C -- Hogan, P G -- Rao, A -- R01 AI 40127/AI/NIAID NIH HHS/ -- R01 GM056203/GM/NIGMS NIH HHS/ -- R01 HL 03601/HL/NHLBI NIH HHS/ -- R43 AI 43726/AI/NIAID NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1999 Sep 24;285(5436):2129-33.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, Harvard Medical School, Boston, MA 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10497131" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Calcineurin/*metabolism ; Calcineurin Inhibitors ; Cell Nucleus/metabolism ; Cyclosporine/pharmacology ; Cytokines/biosynthesis/genetics ; DNA-Binding Proteins/*antagonists & inhibitors/chemistry/metabolism ; Gene Expression Regulation ; Genes, Reporter ; HeLa Cells ; Humans ; Immunosuppressive Agents/chemistry/metabolism/*pharmacology ; Jurkat Cells ; Molecular Sequence Data ; NFATC Transcription Factors ; *Nuclear Proteins ; Oligopeptides/chemistry/metabolism/*pharmacology ; Peptide Library ; Peptides/chemistry/metabolism/*pharmacology ; Phosphorylation ; Recombinant Fusion Proteins/metabolism ; T-Lymphocytes/*drug effects/immunology ; Transcription Factors/*antagonists & inhibitors/chemistry/metabolism ; Transfection
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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