West Nile virus infection in free-ranging squirrels in Illinois.     

Kathleen M Heinz-Taheny  John J Andrews  Michael J Kinsel  Allan P Pessier  Marie E Pinkerton  Karin Y Lemberger  Robert J Novak  George J Dizikes  Eric Edwards  Nicholas Komar 《Journal of veterinary diagnostic investigation》2004,16(3):186-190

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Spread of potato virus Y in potato cultivars (Solanum tuberosum L.) with different levels of sensitivity     

Nata&#x;a Mehle  Maja Kova   Nata&#x;a Petrovi   Maru&#x;a Pompe Novak  &#x;pela Baebler  Hana Kre i Stres  Kristina Gruden  Maja Ravnikar 《Physiological and Molecular Plant Pathology》2004,64(6):19

The aim of this work was to correlate the appearance of the symptoms, multiplication and spread of virus after mechanical inoculation of potato (Solanum tuberosum L.) cultivars showing different levels of susceptibility and sensitivity to Potato virus Y^NTN (PVY^NTN). The potato cultivars used were the resistant cultivar Sante and susceptible cultivars Igor, Pentland squire and Désirée. The spread of the virus PVY^NTN in infected plants was monitored using different methods: DAS-ELISA, tissue printing, immuno-serological electron microscopy and real-time PCR. In all three susceptible cultivars, the virus was detected in the inoculated leaves 4–5 days after inoculation. From there virus spread rapidly, first into the stem, then more or less simultaneously to the upper leaves and roots. Real-time PCR was shown to be very sensitive and enabled viral RNA to be detected in non-inoculated leaves of susceptible cultivar Igor earlier than other methods. Therefore, for exact studies of plant–virus interaction, a combination of methods which detect viruses on the basis of their different properties (coat protein, morphology or RNA) should be used to monitor the spread of viruses.  相似文献   

Akkumulation von Fluoriden in Waldökosystemen     

M. Kühnert  G. Halbwachs  M. Bellusova  C. Nemetz  H. Novak  W. Ruppert  R. Wimmer  H. Zehentner 《European Journal of Forest Research》1993,112(1):64-69

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Flyblock test preparation for cows against bloodsucking insects     

F. I. Vasilevich  S. V. Engashev  V. I. Kolesnikov  P. A. Lemekhov  M. D. Novak 《Russian Agricultural Sciences》2014,40(1):73-75

On the surface of cows’ bodies were detected horseflies Chrysops caecutiens, Chr. pictus, Tabanus bovinus, T. sudeticus; blood-sucking flies Hydrotaea irritans, Haematobia spp., Haematobosca stimulans, Stomoxys calcitrans; and flies with licking mouthparts—Musca autumnalis, Morrelia spp., Fannia canicularis, Musca domestica, Muscina stabulans. The amount of flies on animals in July and August varied: maximum in the first and second decade of July (average of 27–56), quite large amount in late July and early August (14–39), and minimum from mid-August until the first decade of September (3–8). The studies were conducted on 1167 cows and showed high efficacy of Flyblock against zoofilnymi flies, horseflies, and midges. A consecutive period of protective action was established: after 12–14 days, the protective effect coefficient was 97%; after 17–20 days, it was 86%; after 23–27 days, it was 78%; and after 30 days, it was 75%.  相似文献   

Selection parameters for resistance to Fusarium oxysporum f. sp. cubense race 1 and race 4 on diploid banana (Musa acuminata Colla)     

R. Morpurgo  S. V. Lopato  R. Afza  F. J. Novak 《Euphytica》1994,75(1-2):121-129

Summary Shoot tip cultures from banana clones susceptible and resistant to Fusarium oxysporum f. sp. cubense (FOC) race 1 and race 4 were grown in vitro in the presence of different concentrations of fusaric acid and fungal crude filtrates or inoculated with a conidial suspension of FOC to assess correlation between in vivo and in vitro behaviour. Explants were susceptible to both filtrate and fusaric acid irrespective to their known field resistance/susceptibility response. No clear linkage between in vivo and in vitro behaviour was observed and our results suggest that the use of crude filtrate or non-host specific toxin (fusaric acid) in a screening programme for selecting a novel resistant genotype of Musa to FOC is not feasible. When peroxidase activity was used as a parameter to discriminate between sesceptibility and tolerance, results were in good agreement with field response of host plant to pathogens. Early enzymatic activity increased in the incompatible host-pathogen interaction but not in the compatible interaction.Abbreviations IBA Indolebutyric acid - 2iP 6-dimethylallylamino-purine - VCG Vegetative Compatibility Group - FOC Fusarium oxysporum f. sp. cubense - IEF isoelectrofocusing  相似文献   

Nuclear DNA content and in vitro induced somatic polyploidization cassava (Manihot esculenta Crantz) breeding     

F. Awoleye  M. van Duren  J. Dolezel  F. J. Novak 《Euphytica》1994,76(3):195-202

Summary The diploid (2C) amount of DNA in cassava (Manihot esculenta Crantz) is 1.67 picograms (pg) per cell nucleus. This value corresponds to 772 mega-base pairs in the haploid genome. The size of the nuclear genome in cassava is very small in comparison with other Angiosperms. Flow cytometry techniques were used to screen ploidy levels in a large population of in vitro plantlets treated with colchicine and oryzalin (3,5-dinitro-N⁴,N-dipropylsulphate). Culture of axillary node cuttings for 48 hours in liquid medium supplemented with 2.5 to 5.0 mM colchicine in combination with 2% dimethyl sulfoxide (DMSO) resulted in a high frequency (23 to 42%) of non-chimeric tetraploids in the V₃ generation. Although mixoploidy may persist in as many as four cycles of vegetative propagation of node cuttings, solid (non-chimeric) tetraploids can be identified by flow cytometry among in vitro plantlets and then rapidly propagated for field testing. A somatic polyploidization system is proposed for implementation in cassava breeding programmes.Dedicated to the memory of the late Dr. Novak. Correspondence to M. van Duren  相似文献   

Effect of climate change and nitrogen deposition on central-European forests: Regional-scale simulation for South Bohemia     

Fyodor A. Tatarinov  Emil CiencialaPetr Vopenka  Vitaliy Avilov 《Forest Ecology and Management》2011,262(10):1919-1927

The simulation of forest production until 2100 under different environmental scenarios and current management practices was performed using a process-based model BIOME-BGC previously parameterized for the main Central-European tree species: spruce, pine, beech and oak and adapted to include forest management practices. Climatic scenario HadCM3 used in the simulations was taken from the IPCC database created within the 3rd Assessment Report. It was combined with a scenario of CO₂ concentration development and a scenario of N deposition. The control scenario considered no changes of climatic characteristics, CO₂ concentration and N deposition. Simulation experiment was performed for the test region - South Bohemia - using a 1 km × 1 km grid. The actual data on the regional forest cover were aggregated for each grid cell in such a way that each cell represented an even-aged single-dominant species stand or non-forested area, and a standard management scenario depending on the stand age and species was applied to each cell. The effect of environmental variables was estimated as the difference of simulated carbon pools and fluxes in 2050 under environmental changes and under control scenario.The model simulation for the period to 2050 with only climate change under constant CO₂ concentration and N deposition indicated a small decrease of NPP (median values by species reached −0.9 to −1.7% for different species), NBP (−0.3 to −1.7%) and vegetation carbon (−0.3 to −0.7%), whereas soil C slightly increased. Separate increase of N deposition gave small positive effect on carbon pools (0.8-2.9% for wood C and about 0.5% for soil C) and more expressed effect on carbon fluxes (1.8-4.3% for NPP and 1.0-9.7% for NBP). Separate increase of CO₂ concentration lead to 0.6-2.4% increase of wood C pool and 0.1-0.5% increase of soil C. The positive effects of CO₂ concentration and N deposition were more pronounced for coniferous than for deciduous stands.Replacement of 0.5% of coniferous plantations every year by natural broadleaved stands evoked 10.5% of increase of wood carbon pool due to higher wood density of beech and oak compared to spruce and pine, but slightly decreased soil and litter carbon pools.  相似文献   

Outbreak of West Nile virus in North America     

Spielman A  Andreadis TG  Apperson CS  Cornel AJ  Day JF  Edman JD  Fish D  Harrington LC  Kiszewski AE  Lampman R  Lanzaro GC  Matuschka FR  Munstermann LE  Nasci RS  Norris DE  Novak RJ  Pollack RJ  Reisen WK  Reiter P  Savage HM  Tabachnick WJ  Wesson DM 《Science (New York, N.Y.)》2004,306(5701):1473-5; author reply 1473-5

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Thermal Structure and Energy Influx to the Day-and Nightside Venus Ionosphere     

Knudsen WC  Spenner K  Whitten RC  Spreiter JR  Miller KL  Novak V 《Science (New York, N.Y.)》1979,205(4401):105-107

Pioneer Venus in situ measurements made with the retarding potential analyzer reveal strong variations in the nightside ionospheric plasma density from location to location in some orbits and from orbit to orbit. The ionopause is evident at night as a relatively abrupt decrease in the thermal plasma concentration from a few hundred to ten or fewer ions per cubic centimeter. The nightside ion and electron temperatures above an altitude of 250 kilometers, within the ionosphere and away from the terminator, are comparable in magnitude and have a value at the ionopause of approximately 8000 K. The electron temperature increases from a few tens of thousands of degrees Kelvin just outside the ionopause to several hundreds of thoussands of degrees Kelvin further into the shocked solar wind. The coldest ion temperatures measured at an altitude of about 145 kilometers are 140 to 150 K and are still evidently above the neutral temperature. Preliminary day-and nightside model ion and electron temperature height profiles are compared with measured profiles. To raise the model ion temperature to the measured ion temperature on both day-and nightsides, it was necessary to include an ion energy source of the order of 4 x 10(-3) erg per square centimeter per second, presumably Joule heating. The heat flux through the electron gas from the solar wind into the neutral atmosphere averaged over day and night may be as large as 0.05 erg per square centimeter per second. Integrated over the planet surface, this heat flux represents one-tenth of the solar wind energy expended in drag on the sunward ionopause hemisphere.  相似文献   

Excited singlet absorption in 1,2-benzanthracene by the use of nanosecond laser photolysis and spectroscopy     

J R Novak  M W Windsor 《Science (New York, N.Y.)》1968,161(848):1342-1343

Using the technique of laser photolysis and spectroscopy, we have observed excited singlet state absorption bands in 1,2-benzanthracene at 560 and 520 nanometers. The bands decay in less than 50 nanoseconds and are replaced by the known absorption spectrum of the lowest triplet state.  相似文献