Formation of secondary organic aerosols through photooxidation of isoprene   总被引：5，自引：0，他引：5  

Claeys M  Graham B  Vas G  Wang W  Vermeylen R  Pashynska V  Cafmeyer J  Guyon P  Andreae MO  Artaxo P  Maenhaut W 《Science (New York, N.Y.)》2004,303(5661):1173-1176

Detailed organic analysis of natural aerosols from the Amazonian rain forest showed considerable quantities of previously unobserved polar organic compounds, which were identified as a mixture of two diastereoisomeric 2-methyltetrols: 2-methylthreitol and 2-methylerythritol. These polyols, which have the isoprene skeleton, can be explained by OH radical-initiated photooxidation of isoprene. They have low vapor pressure, allowing them to condense onto preexisting particles. It is estimated that photooxidation of isoprene results in an annual global production of about 2 teragrams of the polyols, a substantial fraction of the Intergovernmental Panel on Climate Change estimate of between 8 and 40 teragrams per year of secondary organic aerosol from biogenic sources.  相似文献   

HST2 mediates SIR2-independent life-span extension by calorie restriction     

Lamming DW  Latorre-Esteves M  Medvedik O  Wong SN  Tsang FA  Wang C  Lin SJ  Sinclair DA 《Science (New York, N.Y.)》2005,309(5742):1861-1864

Calorie restriction (CR) extends the life span of numerous species, from yeast to rodents. Yeast Sir2 is a nicotinamide adenine dinucleotide (NAD+-dependent histone deacetylase that has been proposed to mediate the effects of CR. However, this hypothesis has been challenged by the observation that CR can extend yeast life span in the absence of Sir2. Here, we show that Sir2-independent life-span extension is mediated by Hst2, a Sir2 homolog that promotes the stability of repetitive ribosomal DNA, the same mechanism by which Sir2 extends life span. These findings demonstrate that the maintenance of DNA stability is critical for yeast life-span extension by CR and suggest that, in higher organisms, multiple members of the Sir2 family may regulate life span in response to diet.  相似文献   

Physilogically beneficial effects of titanium     

István  Pais  Fehér  Magda  Bokori  József  Nagy  Bálint 《Water, air, and soil pollution》1991,(1):675-680

Titanium is the tenth most common element in the Earth's crust. In soils we find it in form of TiO₂, some titanates and Ti-silicates. Therefore, in most cases Ti is not taken up by plants and therefore, it is not a member of the food chain. Water-soluble and pH-stable chelate form, Ti-ascorbate was applied in plant and animal nutrition. It was demonstrated on a very large scale that Ti-ascorbate has a very avorable, beneficial role in various physiological processes. The results show that Ti should be a member of the family of demonstrated beneficial elements.  相似文献   

Changes induced by powdery mildew in the salicylic acid and polyamine contents and the antioxidant enzyme activities of wheat lines     

Magda P��l  Vikt��ria Kov��cs  Gyula Vida  Gabriella Szalai  Tibor Janda 《European journal of plant pathology / European Foundation for Plant Pathology》2013,135(1):35-47

Investigations were made on four wheat (Triticum aestivum L.) lines under greenhouse conditions, in order to reveal the role of stress-protective materials, namely salicylic acid, polyamines and antioxidant enzymes in the level of tolerance to powdery mildew infection caused by Blumeria graminis (DC.) Speer f.sp. tritici ém. Marchal. The four lines showed different levels of tolerance, assessed on the Saari-Prescott scoring scale: TC26 and TC33 proved to be susceptible and TC9 and TC19 resistant. In most of the lines, infection caused changes in the activities of antioxidant enzymes, especially in the case of guaiacol peroxidase. Four peroxidase isoenzymes, which responded differently to powdery mildew infection could be detected by gel electrophoresis. Infection had only a slight effect on the levels of salicylic acid (free and bound forms) in inoculated plants; while the levels of polyamines, especially spermidine and spermine increased after infection. Correlation analysis was also performed to examine how close a relationship exists between the parameters investigated. It was concluded that salicylic acid, polyamines and antioxidant enzymes have an important role in plant responses and defence mechanisms during this biotic stress and that in some cases there were significant relationships between them. However the levels of these compounds either initially or after pathogen inoculation, could not explain the degree of tolerance to powdery mildew in the four wheat lines investigated.  相似文献   

Chlorella biomass as feed supplement for freshwater fish: sterlet,Acipenser ruthenus     

Magda Sergejevová  Jiří Masojídek 《Aquaculture Research》2012,44(1):157-159

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Counteraction of adriamycin-induced oxidative damage in rat heart by selenium dietary supplementation     

Danesi F  Malaguti M  Nunzio MD  Maranesi M  Biagi PL  Bordoni A 《Journal of agricultural and food chemistry》2006,54(4):1203-1208

Many reports indicate that dietary selenium, potentially increasing the activity of glutathione peroxidase, could offer protection against free-radical-induced damage. The effects of diets moderately enriched in selenium, as sodium selenite or as a lyophilized selenium-rich food, were studied in rats. Adriamycin, an anticancer drug causing a free-radical-mediated cardiotoxicity, was administered intraperitoneally to some rats. The onset of an oxidative damage was indicated by the increase in the plasma level of reactive oxygen metabolites coupled to a decrease in the total antioxidant activity but without modification of glutathione peroxidase activity, which were observed in all rats, independent of the dietary treatment. On the contrary, in the heart, selenium supplementation caused an increase in the total antioxidant activity, glutathione concentration, and glutathione peroxidase and catalase activities leading to a decreased generation of reactive oxygen metabolites. These results clearly indicate that a moderate Se dietary supplementation counteracts adriamycin-induced cardiotoxicity by preservation of endogenous antioxidants.  相似文献   

Beach nourishment: an ecologically sound coastal defence alternative? A review     

Jeroen Speybroeck  Dries Bonte  Wouter Courtens  Tom Gheskiere  Patrick Grootaert  Jean‐Pierre Maelfait  Mieke Mathys  Sam Provoost  Koen Sabbe  Eric W.M. Stienen  Vera Van Lancker  Magda Vincx  Steven Degraer 《水产资源保护:海洋与淡水生态系统》2006,16(4):419-435

• 1. Even though beach nourishment is generally considered as an environment‐friendly option for coastal protection and beach restoration, sizeable impacts on several beach ecosystem components (microphytobenthos, vascular plants, terrestrial arthropods, marine zoobenthos and avifauna) are described in the literature, as reviewed in this paper.
• 2. Negative, ecosystem‐component specific effects of beach nourishment dominate in the short to medium term, with the size of the impact being determined by (1) activities during the construction phase, (2) the quality and (3) the quantity of the nourishment sand, (4) the timing, place and size of project, and (5) the nourishment technique and strategy applied. Over the long term the speed and degree of ecological recovery largely depend on the physical characteristics of the beach habitat, mainly determined by (1) sediment quality and quantity, (2) the nourishment technique and strategy applied, (3) the place and the size of nourishment and (4) the physical environment prior to nourishment.
• 3. The limited information available on indirect and cumulative ecological effects indicates that these effects cannot be neglected in an overall impact assessment. Hence, for ecologically good practice of beach nourishment it is advised (1) to choose nourishment sands with a sediment composition comparable to that of the natural sediment, (2) to avoid short‐term compaction by ploughing immediately after construction, (3) to execute the nourishment in a period of low beach use by birds and other mobile organisms, (4) to choose a number of smaller projects rather than a single large nourishment project and (5) to select the nourishment technique with respect to the local natural values.
• 4. In order to allow an objective, scientifically sound, ecological adjustment of future nourishments, research should aim at (1) taking into account the full sandy beach ecosystem, (2) avoiding strategic imperfections in experimental design and (3) elucidating the biological processes behind impact and recovery of all ecosystem components.

Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Introducing undeinked old newsprint as a new resource of electrical purposes paper     

Tamer Y. A. Fahmy  Fardous Mobarak  Magda G. El-Meligy 《Wood Science and Technology》2008,42(8):691-698

This work introduces, for the first time worldwide, undeinked recycled old newsprint as a new resource of electrical purposes paper. Impregnation of undeinked recycled old newsprint paper with linseed oil enhances the breaking length of paper and remarkably improves its electrical properties, i.e., the dielectric constant increases greatly and the a.c. conductivity decreases significantly due to impregnation. It was found that the electrical properties of the undeinked old newsprint paper and its linseed oil impregnated counterpart are close to the electrical properties of paper made from the more expensive virgin wood pulps and their linseed oil impregnated counterparts. Using the undeinked pulp is more privileged than using the deinked pulp; because eliminating the deinking step saves money, time, and reagents. In addition, eliminating the deinking step improved the breaking length of paper. Electron dispersive X-ray elemental analysis (EDX) was used to investigate the undeinked and deinked pulps for residual elements originating from the printing materials. EDX was correlated to the slight differences in electrical properties of paper made from undeinked and deinked pulps. However, impregnation was able to overcome these slight differences. It was shown that improvement in electrical properties, due to impregnation, is sustained at elevated temperatures.  相似文献   

Efficacy and safety of electrochemotherapy combined with peritumoral IL‐12 gene electrotransfer of canine mast cell tumours          下载免费PDF全文

M. Cemazar  J. Ambrozic Avgustin  D. Pavlin  G. Sersa  A. Poli  A. Krhac Levacic  N. Tesic  U. Lampreht Tratar  M. Rak  N. Tozon 《Veterinary and comparative oncology》2017,15(2):641-654

Electrochemotherapy combined with peritumoral interleukin‐12 (IL‐12) gene electrotransfer was used for treatment of mast cell tumours in 18 client‐owned dogs. Local tumour control, recurrence rate, as well as safety of combined therapy were evaluated. One month after the therapy, no side effects were recorded and good local tumour control was observed with high complete responses rate which even increased during the observation period to 72%. IL‐12 gene electrotransfer resulted in 78% of patients with detectable serum IFN‐γ and/or IL‐12 levels. In the treated tumours vascular changes as well as minimal T‐lymphocytes infiltration was observed. After 1 week, the plasmid DNA was not detected intra‐ or peritumorally and no horizontal gene transfer was observed. In summary, our study demonstrates high antitumour efficacy of electrochemotherapy combined with IL‐12 electrotransfer, which also prevented recurrences or distant metastases, as well as its safety and feasibility in treatment of canine mast cell tumours.  相似文献   

Molecular characterization of the VP1 gene of a Mexican isolate of infectious pancreatic necrosis virus     

Barrera-Mejía M  Simón-Martínez J  Ulloa-Arvizu R  Salgado-Miranda C  Soriano-Vargas E 《Canadian journal of veterinary research》2010,74(3):218-222

The presence of infectious pancreatic necrosis virus (IPNV) in salmonids predominantly produces a high mortality rate in first-feeding fry. Genomic analysis of the vp2 gene sequence is most commonly used to determine the genetic diversity of IPNV isolates. Recently, information obtained from the vp1 gene allowed for efficient analysis of the genetic diversity of IPNV. In this study, the vp1 gene from a Mexican IPNV isolate was characterized and compared with IPNV isolates from Europe, North America, and Asia. The results indicate that the Mexican isolate is most closely related genetically to the 2310 strain from Spain.  相似文献