| 1. |
- Friberg, Hanna, et al.
(författare)
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Effect of earthworms and incorporation of grass on Plasmodiophora brassicae
- 2008
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Ingår i: Pedobiologia. - : Elsevier BV. - 1873-1511 .- 0031-4056. ; 52:1, s. 29-39
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Tidskriftsartikel (refereegranskat)abstract
- The resting spores of Plasmodiophora brassicae, causal agent of clubroot disease of crucifers, are tolerant structures with the abitity to survive for at least 15 years in soil waiting for a host. The influence of incorporation of cut grass (Lolium perenne) and presence of the earthworm Aporrectodea caliginosa on R brassicae resting spores was investigated in a microcosm experiment, and measured as disease development in susceptible bait plants (Brassica rapa var. pekinensis). Grass material was incorporated every other month during 498 days of experiment, and soil samples for P brassicae bioassay were collected nine times, just before each incorporation of grass. The grass treatment, irrespective of earthworm presence, resutted in a tower soil pH, increased the proportion of large soil. aggregates and increased the abundance of mites, collembolans and nematodes. The microbial biomass (SIR) was increased by grass incorporation, as a result of an increase in growing microbial biomass. When earthworms were present, the response of the microbial community was more pronounced, and the organic material. was mineralised more efficiently, leading to a higher percentage ash content of the soil. In contrary to these changes, clubroot disease severity did not differ among the treatments at any specific sampling. Across all samplings, however, disease severity was higher in the grass treatment without earthworms compared with the control treatment. The result contradicts earlier studies on earthworm effects on P brassicae. The importance of different earthworm species on the interaction is discussed. (c) 2008 Elsevier GmbH. All rights reserved.
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| 2. |
- Terhivuo, Juhani, et al.
(författare)
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Clone distribution of the earthworm Eiseniella tetraedra (Sav.) (Oligochaeta : Lumbricidae) across an altitudinal gradient on subarctic mountains of NW Europe
- 2008
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Ingår i: Pedobiologia. - Jena : Elsevier. - 0031-4056 .- 1873-1511. ; 51:5-6, s. 375-384
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Tidskriftsartikel (refereegranskat)abstract
- In earlier studies, we have shown that clone diversity of the parthenogenetic earthworm Eiseniella tetraedra increases from the upper reaches of rivers in northern Sweden towards their mouths. Now we survey brooks in the Scandes Mountains in the watershed between Sweden and Norway where major rivers originate. Using starch get enzyme electrophoresis, we found 37 clones in a total catch of 379 individuals from six mountains. The most abundant clone made up 48.3% of the individuals collected. It was present on most mountains and was found at different elevations. In comparison with other clones it may represent a general-purpose genotype adapted to environmental conditions ranging from alpine through to subalpine to boreal habitats in the mountains. Diversity of clone assemblages decreased with increasing elevation. On four mountains, one to two clones were found at higher elevations. Passive downstream dispersal of E. tetraedra propagules from wider areas of the mountains was responsible for the more diverse clone pools in the tower reaches of the brooks (i.e., "small rivers behave like large ones"). Two clone groups, which deviated from the norm clone in their number of enzyme variants, were evenly distributed among different elevations. Therefore, we could not correlate genotype differences (i.e., adaptation of clones to mountain elevations). Clone pool similarities among the mountains were tow on average (range 0-58%) but in a cluster of four mountains, similarities varied from 46% to 58%. Clone pool similarities between different elevations of the same mountain ranged from 27% to 83%. One mountain brook was sampled over 3 years to assess clone turnover. Only the norm clone was found in upstream habitats but it and three other clones were recorded downstream in at least 2 years. Ten clones were found once in the latter habitat as well.
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| 3. |
- Abazov, V. M., et al.
(författare)
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Measurement of sigma(p(p)over-bar -> Z plus X)Br(Z -> tau(+)tau(-)) at root s=1.96 TeV
- 2009
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 670:4-5, s. 292-299
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the cross section for Z boson production times the branching fraction to tau lepton pairs sigma(p (p) over bar -> Z + X)Br(Z -> tau(+)tau(-)) in p (p) over bar collisions at root s = 1.96 TeV. The measurement is performed in the channel in which one tau lepton decays into a muon and neutrinos. and the other tau lepton decays hadronically or into an electron and neutrinos. The data sample corresponds to an integrated luminosity of 1.0 fb(-1) collected with the DO detector at the Fermilab Tevatron Collider. The sample contains 1511 candidate events with an estimated 20% background from jets or muons misidentified as tau leptons. We obtain sigma . Br = 240 +/- 8 (star) +/- 12 (sys) +/- 15 (lum) pb, which is consistent with the standard model prediction.
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| 4. |
- Matura, M, et al.
(författare)
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Selected oxidized fragrance terpenes are common contact allergens
- 2005
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Ingår i: Contact Dermatitis. - : Wiley. - 0105-1873 .- 1600-0536. ; 52:6, s. 320-328
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Tidskriftsartikel (refereegranskat)abstract
- Terpenes are widely used fragrance compounds in fine fragrances, but also in domestic and occupational products. Terpenes oxidize easily due to autoxidation on air exposure. Previous studies have shown that limonene, linalool and caryophyllene are not allergenic themselves but readily form allergenic products on air-exposure. This study aimed to determine the frequency and characteristics of allergic reactions to selected oxidized fragrance terpenes other than limonene. In total 1511 consecutive dermatitis patients in 6 European dermatology centres were patch tested with oxidized fragrance terpenes and some oxidation fractions and compounds. Oxidized linalool and its hydroperoxide fraction were found to be common contact allergens. Of the patients tested, 1.3% showed a positive reaction to oxidized linalool and 1.1% to the hydroperoxide fraction. About 0.5% of the patients reacted to oxidized caryophyllene whereas 1 patient reacted to oxidized myrcene. Of the patients reacting to the oxidized terpenes, 58% had fragrance-related contact allergy and/or a positive history for adverse reaction to fragrances. Autoxidation of fragrance terpenes contributes greatly to fragrance allergy, which emphasizes the need of testing with compounds that patients are actually exposed to and not only with the ingredients originally applied in commercial formulations.
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