Jet and accretion-disk emission untangled in 3C 273     

Grandi P  Palumbo GG 《Science (New York, N.Y.)》2004,306(5698):998-1002

A long-term spectral variability study of 3C 273 on data obtained by BeppoSAX allows us to decouple the beamed nonthermal (jet) and unbeamed thermal (accretion flow) radiation produced in the inner region of a radio-loud active galactic nucleus. Jet power, when compared with unbeamed radiation, increases with energy. The thermal component is generally overwhelmed by the nonthermal radiation, by a factor of 1.2 to 3 in the 2- to 10-keV range and up to a factor of 7 above 20 keV. In only one case, the accretion flow overcomes the jet, allowing the K(alpha) iron line to emerge clearly over the continuum.  相似文献   

A green algal apicoplast ancestor     

Funes S  Davidson E  Reyes-Prieto A  Magallón S  Herion P  King MP  González-Halphen D 《Science (New York, N.Y.)》2002,298(5601):2155

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Activation of FOXO1 by Cdk1 in cycling cells and postmitotic neurons     

Yuan Z  Becker EB  Merlo P  Yamada T  DiBacco S  Konishi Y  Schaefer EM  Bonni A 《Science (New York, N.Y.)》2008,319(5870):1665-1668

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Small bilaterian fossils from 40 to 55 million years before the cambrian   总被引：1，自引：0，他引：1  

Chen JY  Bottjer DJ  Oliveri P  Dornbos SQ  Gao F  Ruffins S  Chi H  Li CW  Davidson EH 《Science (New York, N.Y.)》2004,305(5681):218-222

Ten phosphatized specimens of a small (<180 micrometers) animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, dating from 40 to 55 million years before the Cambrian. Seen in sections, this animal (Vernanimalcula guizhouena gen. et sp. nov.) had paired coeloms extending the length of the gut; paired external pits that could be sense organs; bilateral, anterior-posterior organization; a ventrally directed anterior mouth with thick walled pharynx; and a triploblastic structure. The structural complexity is that of an adult rather than a larval form. These fossils provide the first evidence confirming the phylogenetic inference that Bilateria arose well before the Cambrian.  相似文献   

Edible neotropical blueberries: antioxidant and compositional fingerprint analysis   总被引：1，自引：0，他引：1  

Dastmalchi K  Flores G  Petrova V  Pedraza-Peñalosa P  Kennelly EJ 《Journal of agricultural and food chemistry》2011,59(7):3020-3026

Edible blueberry species are well recognized for their potential health benefits. Ericaceae fruits including the North American highbush blueberry (Vaccinium corymbosum L.) and five less common edible blueberry relatives from the New World tropics, Anthopterus wardii Ball, Cavendishia grandifolia Hoerold, Macleania coccoloboides A. C. Smith, Sphyrospermum buxifolium Poeppig & Endlicher, and Sphyrospermum cordifolium Benth, were investigated for their antioxidant properties and phenolic profiles. The neotropical berries C. grandifolia and A. wardii exhibited significantly higher 1,1-diphenyl-2-picrylhydrazyl (DPPH(?)) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS(??+)) free radical scavenging and iron chelation activities than V. corymbosum. Total phenolic content and high-performance liquid chromatography with photodiode array detection (HPLC-PDA) compositional fingerprint analyses were also carried out. Significant correlations were observed among total phenolic contents, DPPH(?) and ABTS(??+) scavenging, and iron chelation activities. By use of HPLC-PDA, the phenolic constituents in the berries were identified as chlorogenic acid, p-coumaric acid, hyperoside, quercetin-3-O-glucoside, isoorientin, isovitexin, orientin and vitexin. Principal component analysis reduced the dimensions of antioxidant and total phenolic data to two components, which accounted for 95% of total variation among the six fruits. Each fruit species formed its own cluster, and therefore the antioxidant profile of each species was shown to be distinct.  相似文献   

Unusual case of uterine stump pyometra in a cat     

Rota A  Pregel P  Cannizzo FT  Sereno A  Appino S 《Journal of Feline Medicine and Surgery》2011,13(6):448-450

This report describes an unusual case of uterine stump pyometra in a cat whose main clinical sign at presentation was abdominal straining. At the time of ovariohysterectomy, the surgeon reported that the uterine body had a purulent content. Nearly a month after the surgery the cat showed abdominal straining. The enlarged uterine stump, filled with purulent fluid, had caused a compression of the rectum and secondary intestinal sub-occlusion. Surgical revision consisted of draining the purulent content of the remnant of the uterine body and ablating as much of it as possible; checking of the ovarian pedicles revealed the presence of a small fragment of whitish tissue on the right side, which was shown to contain, by means of histological observation and immunohistochemical staining, ovarian tissue. Four months after surgical revision the queen did not show any pathological signs and 1 year later she is still in good health.  相似文献   

ROS and NO production in compatible and incompatible tomato-<Emphasis Type="Italic">Meloidogyne incognita</Emphasis> interactions     

Maria Teresa Melillo  Paola Leonetti  Antonella Leone  Pasqua Veronico  Teresa Bleve-Zacheo 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(4):489-502

Nitric oxide (NO) has been shown to be an essential regulatory molecule in plant response to pathogen infection in synergy with reactive oxygen species (ROS). At the present, nothing is known about the role of NO in disease resistance to nematode infection. We used a resistant tomato cultivar with different sensitivity to avirulent and virulent populations of the root-knot nematode Meloidogyne incognita to investigate the key components involved in oxidative and nitrosative metabolism. We analyzed the superoxide radical production, hydrogen peroxide content, and nitric oxide synthase (NOS)-like and nitrate reductase activities, as potential sources of NO. A rapid NO accumulation and ROS production were found at 12 h after infection in compatible and incompatible tomato-nematode interactions, whereas the amount of NO and ROS gave different results 24 and 48 h after infection amongst compatible and incompatible interactions. NOS-like arginine-dependent enzyme rather than nitrate reductase was the main source of NO production, and NOS-like activity increased substantially in the incompatible interaction. We can envisage a functional overlap of both NO and ROS in tomato defence response to nematode invasion, NO and H₂O₂ cooperating in triggering hypersensitive cell death. Therefore, NO and ROS are key molecules which may help to orchestrate events following nematode challenge, and which may influence the host cellular metabolism.  相似文献   

High levels of genetic differentiation between Wolbachia-infected and non-infected populations of Folsomia candida (Collembola, Isotomidae)     

Francesco Frati  Ilaria Negri  Pietro P. Fanciulli  Marco Pellecchia  Vincenzo De Paola  Valerio Scali  Romano Dallai 《Pedobiologia》2004,48(5-6):461-468

The Gram-negative -Proteobacterium Wolbachia pipientis has been described as an obligate endosymbiont in many arthropod species, where it induces a variety of reproductive alterations, including parthenogenesis. Recently, this microorganism has also been detected in the parthenogenetic collembolan Folsomia candida. Here, we confirm the occurrence of the endosymbiont also in two Italian parthenogenetic populations of F. candida using ultrastructural (electron microscopy) and molecular (PCR screening on two bacterial genes) evidence. The strain isolated in the Italian populations has almost-identical gene sequences compared to that previously isolated in other populations of F. candida. In addition, we discovered a population of Folsomia cf. candida, which showed the presence of both males and females. This population is not infected by Wolbachia. A screening of two mitochondrial genes (COI and COII) showed that the bisexual population has high levels of genetic divergence in comparison with the parthenogenetic ones, even suggesting the possibility that it belongs to a different species. Furthermore, the remarkably high levels of genetic divergence between the two parthenogenetic populations suggests a possible influence of Wolbachia on inducing such differentiation, and, in the long term, speciation.  相似文献   

Influence of urease and nitrification inhibitors on N losses from soils fertilized with urea   总被引：10，自引：0，他引：10  

Paola Gioacchini  Anna Nastri  Claudio Marzadori  Camilla Giovannini  Livia Vittori Antisari  Carlo Gessa 《Biology and Fertility of Soils》2002,36(2):129-135

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Hydroxymethanesulphinate salts and related decomposition products in wastewater     

Emilia Barbolani Piccardi  Paola Legittimó Cellini 《Water, air, and soil pollution》1978,9(3):301-307

Hydroxymethanesulphinate (HMS) and its decomposition products such as HCHO, Zn and sulphites can be determined quantitatively in each other's presence by a polarographic method. In the alkaline medium it is possible to have well defined and separated waves relative to the oxidation of HMS ion and to the reduction of HCHO and zincate ion. The quantitative determination of these compounds is carried out with standard addition methods since the concentration-current relationship is linear. The SO₂ is determined in HClO₄ 0.1 M and in the same sample it is possible to determine even HMS, HCHO and Zn after addition of NaOH up to 0.1 M. Moreover, a method of indirect determination of HMS is herein described. This is based on the determination of HCHO released by means of a weak oxidation of HMS which is stoichiometrically proportional to the total HMS. The method is sensitive and is made specific for such types of wastewater which come from textile industries.  相似文献