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941.
草地螟2007年越冬代成虫迁飞行为研究与虫源分析 总被引:16,自引:0,他引:16
草地螟 Loxostege sticticalis L.是危害我国北方农牧业的一种重要迁飞性害虫,明确草地螟的虫源地及迁飞路线对其早期预警具有重要意义。本文利用垂直监测昆虫雷达的长期观测,迁飞高峰期雌虫卵巢解剖、大区环流分析、各地虫情信息收集和利用Hysplit_4模型进行轨迹分析,研究了2007年越冬代草地螟的空中迁飞行为和东北地区严重暴发的草地螟虫源。结果表明:6月7–9日,雷达观测点诱虫灯内草地螟具有典型迁飞昆虫生理特征;草地螟主要在夜间迁飞,飞行高度集中在300~500 m,400 m是主要飞行高度,迁飞高峰期夜间迁移可持续9 h。东北地区严重发生的草地螟虫源,一部分来自内蒙古乌盟地区,一部分来自蒙古共和国中东部及中俄边境地区。据此推测我国与国外草地螟存在虫源交流。 相似文献
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Mihaela ChivuEconomescu Coralia Bleotu Camelia Grancea Daniela Chiriac Anca Botezatu Iulia V. Iancu Ioana Pitica Laura G. Necula Ana Neagu Lilia Matei Denisa Dragu Camelia Sultana Elena L. Radu Alina Nastasie Oana Voicu Marius Ataman Saviana Nedeianu Cristina Mambet Carmen C. Diaconu Simona Maria Ruta 《Journal of cellular and molecular medicine》2022,26(4):1293
SARS‐CoV‐2 vaccines are highly efficient against severe forms of the disease, hospitalization and death. Nevertheless, insufficient protection against several circulating viral variants might suggest waning immunity and the need for an additional vaccine dose. We conducted a longitudinal study on the kinetics and persistence of immune responses in healthcare workers vaccinated with two doses of BNT162b2 mRNA vaccine with or without prior SARS‐CoV‐2 infection. No new infections were diagnosed during follow‐up. At 6 months, post‐vaccination or post‐infection, despite a downward trend in the level of anti‐S IgG antibodies, the neutralizing activity does not decrease significantly, remaining higher than 75% (85.14% for subjects with natural infection, 88.82% for vaccinated after prior infection and 78.37% for vaccinated only). In a live‐virus neutralization assay, the highest neutralization titres were present at baseline and at 6 months follow‐up in persons vaccinated after prior infection. Anti‐S IgA levels showed a significant descending trend in vaccinated subjects (p < 0.05) after 14 weeks. Cellular immune responses are present even in vaccinated participants with declining antibody levels (index ratio 1.1–3) or low neutralizing activity (30%–40%) at 6 months, although with lower T‐cell stimulation index (p = 0.046) and IFN‐γ secretion (p = 0.0007) compared to those with preserved humoral responses. 相似文献
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Interactive effects of elevated atmospheric CO2 and arbuscular mycorrhizal (AM) fungi on biomass production and N2 fixation were investigated using black locust ( Robinia pseudoacacia ). Seedlings were grown in growth chambers maintained at either 350 μmol mol−1 or 710 μmol mol−1 CO2 . Seedlings were inoculated with Rhizobium spp. and were grown with or without AM fungi. The 15 N isotope dilution method was used to determine N source partitioning between N2 fixation and inorganic fertilizer uptake. Elevated atmospheric CO2 significantly increased the percentage of fine roots that were colonized by AM fungi. Mycorrhizal seedlings grown under elevated CO2 had the greatest overall plant biomass production, nodulation, N and P content, and root N absorption. Additionally, elevated CO2 levels enhanced nodule and root mass production, as well as N2 fixation rates, of non- mycorrhizal seedlings. However, the relative response of biomass production to CO2 enrichment was greater in non-mycorrhizal seedlings than in mycorrhizal seedlings. This study provides strong evidence that arbuscular mycorrhizal fungi play an important role in the extent to which plant nutrition of symbiotic N2 -fixing tree species is affected by enriched atmospheric CO2 . 相似文献
947.
Phytotoxicity of nickel (Ni) varies within plant species and cultivars as well as with the concentration of Ni in the rooting
medium. Moreover, it is known that several nutrients can modify the plant response to excess Ni. Nitrogen can be absorbed
by plants as different N forms and because N metabolism and Ni are closely related, a hydroponic experiment was conducted
to study the effect of Ni toxicity on the growth, nutrient status of the different plant parts and leaf chlorophyll concentrations
in sunflower plants (Helianthus annuus L.) cv Quipu grown with different forms of N supply. The plants were grown under controlled
conditions for 35 days. Depending on the N source supplied, there were significant differences in the sensitivity of sunflower
plants to excess Ni. Tolerance was lowest when grown with NO3
− alone. A high Ni and NO3
− as the only N source resulted in reduced dry weight and significant decreases in nutrient concentration. Plants supplied
with a mixture of NO3
− and NH4
+ absorbed in the presence of Ni in solution about three times less Ni than those supplied with NO3
− alone. Consequently, there were great differences in Ni concentrations between treatments. With a N nutrition of 100% NO3
−-N, Ni supply led to severe growth inhibition. Just contrary, simultaneous supply of NO3
− and NH4
+ not only reduced Ni toxicity, but growth was even stimulated by Ni if supplied to plants fed with NO3
− and NH4
+. This indicates the significant role of the N form supplied in the behaviour of Ni toxicity in sunflower plants.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
948.
The main host carbon energy source transferred from wheat leaves (Triticum aestivum L.) to wheat powdery mildew (Erysiphe graminis f.sp. tritici) has been investigated in three ways. When the uptake of sugars by isolated mycelial suspensions was examined, the uptake
rate for glucose was considerably higher than that for a range of other solutes. Analysis by high-performance liquid chromatography
of leaf and mycelial extracts following uptake of sugars into infected leaf pieces confirmed that sucrose was rapidly hydrolyzed
in the leaf; no sucrose or fructose could be detected in mycelial extracts. Furthermore, studies of the uptake of asymmetrically
labelled sucrose indicated that this sugar is cleaved prior to uptake by the pathogen. Thus several lines of evidence show
that glucose, and not sucrose, is the major carbon energy source transferred from host to fungal mycelium.
Received: 11 November 1998 / Accepted: 18 January 1999 相似文献
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J. Behnke P. McGregor J. Cameron I. Hartley M. Shepherd F. Gilbert C. Barnard J. Hurst S. Gray R. Wiles 《Journal of Zoology》1999,248(3):337-347