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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Using LC-MSMS to assess glutathione levels in South African white grape juices and wines made with different levels of oxygen     

du Toit WJ  Lisjak K  Stander M  Prevoo D 《Journal of agricultural and food chemistry》2007,55(8):2765-2769

The effect of oxygen on the levels of glutathione, an important antioxidant, in must and wine was studied using a novel LC-MSMS method for the analysis of reduced and oxidized glutathione. This study found that the storage of grape juice at high SO2 and ascorbic acid levels at -20 degrees C did not lead to a decrease in reduced glutathione levels. The effect of varying the oxygen levels in South African white grape juices, which included a reductive treatment (less than 0.3 mg/L dissolved O2 added), a control treatment (between 1.0 and 1.5 mg/L dissolved O2 added), and an oxidative treatment (3.5-4 mg/ L dissolved O2 added, without SO2) on reduced glutathione levels in the juice and resulting wine was also investigated. A custom build press was used to press whole bunches of two different Sauvignon Blanc and Colombard grapes. Alcoholic fermentation and oxygen additions to the must led to lower reduced glutathione levels in the wine. Reduced glutathione levels were only significantly higher in the wine made from reductive juice that had the highest initial reduced glutathione levels in the grapes.  相似文献   

Can the structure of dormant cambium and the widths of phloem and xylem increments be used as indicators for tree vitality?     

Jožica Gričar  Špela Jagodic  Bogoslav Šefc  Jelena Trajković  Klemen Eler 《European Journal of Forest Research》2014,133(3):551-562

We investigated the structure and width of the dormant cambium and of the increments of phloem and xylem of Quercus robur to estimate their potential as indicators for tree vitality. The samples were taken from three woodlands, two in Slovenia [Krakovo forest (KRA) and Murska Suma (MUS)] and one in Croatia [Kobiljak (KOB)], with reported tree decline. The number of dormant cells seems to reflect the initial capacity of the cambium to accomplish cell division. With the exception of two trees at KRA, cell production was always higher on the xylem side than on the phloem side. The annual phloem increments were narrower, less variable among trees and with clear lower and upper limits. With increased cambial cell productivity, the share of the xylem in the total annual radial increment increased following a curvilinear function. In trees with an annual radial increment >3.5 mm, the xylem size represented more than 90 % of the total radial growth. The anatomical variables analyzed show that the most limiting environmental conditions seem to prevail at KRA, whereas the conditions at MUS seem to be most favorable in terms of radial growth. Analysis of the width and structure of xylem and phloem increments, the number of dormant cambial cells and their inter-relationships can provide additional information on the vitality of oaks.  相似文献   

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   

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