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排序方式: 共有369条查询结果,搜索用时 31 毫秒
1.
Bovine neutrophil chemotactic activity was detected in the supernatant fluid of logarithmic phase cultures of P. haemolytica serotype 1. The chemoattractant was produced under culture conditions suitable for P. haemolytica leukotoxin production. An inverse correlation existed between the leukotoxin LC50 and the chemotactic activity in the culture fluid. Elimination of leukotoxin activity by heating, dilution or ultrafiltration, exposed the chemotactic activity in the culture fluid. The chemoattractant was partially resistant to heating (60 degrees C, 30 min), and had an apparent molecular weight greater than 100,000. Detection of chemotactic activity in both the concentrate and filtrate after XM300 filtration suggested that there might be more than one component with chemotactic activity or else that polymerization was occurring. Production of a potent neutrophil chemoattractant by P. haemolytica may explain the rapid infiltration of neutrophils that occurs during the early stages of bovine pneumonic pasteurellosis. 相似文献
2.
Joo Carlos de Moraes S Lucien Sguy Florent Tivet Rattan Lal Serge Bouzinac Paulo Rogrio Borszowskei Clever Briedis Josiane Burkner dos Santos Daiani da Cruz Hartman Clayton Giani Bertoloni Jadir Rosa Theodor Friedrich 《Land Degradation \u0026amp; Development》2015,26(6):531-543
The continuous use of plowing for grain production has been the principal cause of soil degradation. This project was formulated on the hypothesis that the intensification of cropping systems by increasing biomass‐C input and its biodiversity under no‐till (NT) drives soil restoration of degraded agro‐ecosystem. The present study conducted at subtropical [Ponta Grossa (PG) site] and tropical regions [Lucas do Rio Verde, MT (LRV) site] in Brazil aimed to (i) assess the impact of the continuous plow‐based conventional tillage (CT) on soil organic carbon (SOC) stock vis‐à‐vis native vegetation (NV) as baseline; (ii) compare SOC balance among CT, NT cropping systems, and NV; and (iii) evaluate the redistribution of SOC stock in soil profile in relation to soil resilience. The continuous CT decreased the SOC stock by 0·58 and 0·67 Mg C ha−1 y−1 in the 0‐ to 20‐cm depth at the PG and LRV sites, respectively, and the rate of SOC sequestration was 0·59 for the PG site and ranged from 0·48 to 1·30 Mg C ha−1 y−1 for the LRV site. The fraction of C input by crop residues converted into SOC stock was ~14·2% at the PG site and ~20·5% at the LRV site. The SOC resilience index ranged from 0·29 to 0·79, and it increased with the increase in the C input among the NT systems and the SOC sequestration rates at the LRV site. These data support the hypothesis that NT cropping systems with high C input have a large potential to reverse the process of soil degradation and SOC decline. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
3.
Fariba Ghaderi Bahram Sharifnabi Mohammad Javan-Nikkhah Patrick C. Brunner Bruce A. McDonald 《Plant pathology》2020,69(8):1482-1491
The centre of origin of the globally distributed wheat pathogen Parastagonospora nodorum has remained uncertain because only a small number of isolates from the Fertile Crescent were included in earlier population genetic and phylogeographic studies. We isolated and genetically analysed 193 P. nodorum strains from three naturally infected wheat fields distributed across Iran using 11 neutral microsatellite loci. Compared to previous studies that included populations from North America, Europe, Africa, Australia, and China, the populations from Iran had the highest genetic diversity globally and also exhibited greater population structure over smaller spatial scales, patterns typically associated with the centre of origin of a species. Genes encoding the necrotrophic effectors SnToxA, SnTox1, and SnTox3 were found at a high frequency in the Iranian population. By sequencing 96 randomly chosen Iranian strains, we detected new alleles for all three effector genes. Analysis of allele diversity showed that all three effector genes had higher diversity in Iran than in any population included in previous studies, with Iran acting as a hub for the effector diversity that was found in other global populations. Taken together, these findings support the hypothesis that P. nodorum originated either within or nearby the Fertile Crescent with a genome that already encoded all three necrotrophic effectors during its emergence as a pathogen on wheat. Our findings also suggest that P. nodorum was the original source of the ToxA genes discovered in the wheat pathogens Phaeosphaeria avenaria f. sp. tritici 1, Pyrenophora tritici-repentis, and Bipolaris sorokiniana. 相似文献
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Friedrich Mechelke 《Genetic Resources and Crop Evolution》1955,3(1):127-135
Zusammenfassung Die Gerstensorte Heines Haisa und die PrimitivformHordeum agriocrithon sind sommerannuell. Beide reagieren auf den Einfluß niedriger Temperaturen während der Keimung mit der Ausbildung einer spezialsegmentartigen Einschnürung im kurzen Arm des VII. Chromosoms in Wurzelspitzen-Metaphasen. Im Gegensatz dazu ist bei der winterannuellen Form Friedrichswerther Berg und dem annähernd winterannuellenHordeum spontaneum die Tendenz zu der gleichen Reaktion bedeutend geringer oder überhaupt nicht vorhanden. Die Möglichkeit, daß die Eigenschaft sommer- bzw. winterannuell in Beziehung zur Funktion heterochromatischer Segmente steht, wird kurz diskutiert. 相似文献
6.
I L Bonaccorsi H M McNair L A Brunner P Dugo G Dugo 《Journal of agricultural and food chemistry》1999,47(10):4237-4239
A fast HPLC method for the determination of the oxygen heterocyclic compounds of citrus essential oils was developed. Five different oils were analyzed under identical conditions, by reversed-phase HPLC with photodiode array detector, for a direct comparison of the composition of their oxygen heterocyclic fraction. Analysis time was 7 min. The oils analyzed were lemon, bergamot, mandarin, sweet orange, and bitter orange. The method developed is good for rapid screening or fingerprinting of these essential oils; a slightly slower method is recommended for higher resolution and better quantitative results. 相似文献
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Friedrich Moll 《Forstwissenschaftliches Centralblatt》1925,47(3):225-230
Ohne Zusammenfassung 相似文献
10.
Dr. Friedrich Zacher 《Journal of pest science》1935,11(6):63-66
Ohne Zusammenfassung
Mit 1 Abbildung. 相似文献