运用噬菌体随机肽库筛选与DON毒素特异结合的亲和肽段

为获得与毒素脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON)高亲和力的特异性多肽,利用丁基硼酸封闭法制备DON人工抗原DON-HG-BSA,以其为靶分子筛选噬菌体肽库,对阳性克隆进行DNA序列测定与氨基酸推导,并进行亲和特异性验证。结果显示,经过4轮亲和肽段筛选与酶联免疫检测法鉴定,从M13噬菌体随机7肽库中得到15个DON人工抗原包被孔与牛血清白蛋白包被孔OD比值大于3.8的阳性克隆,其中10个与DON人工抗原高亲和力结合的阳性克隆经测序后共推导出4种多肽序列。经抗原梯度酶联免疫检测法验证,多肽MAPGWVP与DON人工抗原浓度的相关性高达0.99,对人工抗原具有高亲和力。该多肽的获得将为进一步开发高效的DON诊断试剂盒奠定基础。     

Effects of two contrasting agricultural land‐use practices on nitrogen leaching in a sandy soil of Middle Germany

The objective of this study is to evaluate different agricultural land‐use practices in terms of N leaching and to give recommendations for a sustainable agriculture on sandy soils in Middle Germany. Soil mineral N (N_min) and leachate N were quantified at a sandy soil in N Saxony during 3 years. Two treatments were applied: intensive (I)—using inorganic and organic fertilizer and pesticides, and organic (O)—exclusively using organic fertilizer, legume‐based crop rotation, and no pesticides. Split application of mineral fertilizers did not result in substantial N losses at treatment I. Legumes induced a considerable increase of soil mineral N and particularly of leachate mineral N (N_{min_perc}) at treatment O. High N_{min_perc} concentrations (up to 78 mg N L^–1) were observed during as well as after the cultivation of legumes. These high N_{min_perc} concentrations are the reason why clearly higher N_{min_perc} losses were determined at treatment O (62 kg N ha^–1 y^–1) compared to treatment I (23 kg N ha^–1 y^–1). At both treatments, the quantity of N losses was strongly affected by the precipitation rates. Concentrations and losses of dissolved organic N (DON_perc) were assessed as above average at both treatments. The results suggest that the DON_perc concentration is influenced by precipitation, soil coverage, and organic fertilizers. Higher values were determined in the percolation water of treatment O. The average annual DON_perc losses amounted to 15 kg N ha^–1 at I and to 32 kg N ha^–1 at O. The average monthly percentage of DON_perc losses on the loss of the dissolved total N of percolation water (DTN_perc) ranged between <1% and 55% at O and between 2% and 56% at I. For the whole measuring period of 29 months, the relative amounts of DON_perc of DTN_perc (21% at O and 25% at I) were more or less the same for both treatments. The results show that DON_perc can contribute significantly to the total N loss, confirming the importance to consider this N fraction in N‐leaching studies. It was concluded that at sandy sites, a split application of mineral fertilizers, as applied at treatment I, seems to be more expedient for limiting the N leaching losses than legume‐based crop rotations.     

In situ carbon and nitrogen dynamics in ryegrass-clover mixtures: Transfers, deposition and leaching

Carbon (C) and nitrogen (N) dynamics in a third production year ryegrass-clover mixture were investigated in the field. Cylinders (diameter 29.7 cm) were installed to depths of 20, 40 and 60 cm and equipped with suction cups to collect percolating pore water. Ryegrass and clover leaves were cross-labelled with ¹⁴C- and ¹⁵N-enriched urea and the fate of the two tracers was studied for 3 months during summer. Transfer of ¹⁴C occurred mainly from ryegrass to clover, whereas the largest transfer of ¹⁵N was in the opposite direction. The average transfer of N from clover was 40% (SE±3.1, n=9) of N in ryegrass, whereas the fraction of N in clover donated by ryegrass was 5% (±1.2, n=9). The amount of ¹⁴C transferred from ryegrass to clover was 1.7% (±0.1, n=9) of the ¹⁴C-activity in the total above-ground plant biomass found in the unlabelled clover and with a transfer from clover to ryegrass being 0.4% (±0.1, n=9). ¹⁵N-enriched compounds were not detected in percolating pore water, which may be caused by either dilution from irrigation or low availability of leachable N compounds. ¹⁴C was found solely as ¹⁴CO₂ in the pore water indicating that dissolved organic carbon (DOC) did not originate from fresh root deposits. Transfer of ¹⁴C between the two species in the mixed crop alongside with high transfer of ¹⁵N despite a large percolation of pore water indicates that part of the N transfer occurred in non-leachable N-forms. The amount of N transferred between the two species was found to depend on the ratio between dry matter accumulated in the donating and receiving species, the ¹⁴C-allocation within the receiving species and the root turnover rate in the soil.     

小麦赤霉病发病程度与DON含量的关系

 采用田间判断小麦赤霉病的发病级别或者检测刚收获小麦的病粒率,分析小麦赤霉病田间发病级别与其麦粒脱氧雪腐镰刀菌烯醇(DON)含量之间以及病粒率与麦粒DON含量之间的关系,结果表明它们之间都有极显著的相关性。小麦田间发病级别为2级以上时,麦粒的DON含量> 1000μg/kg,4级以上时,麦粒的DO N含量> 2000μ g/kg;在病粒率< 25%时,DO N含量< 1200μg/kg,病粒率在25%~40%时,DON含量为1200~2200μg/kg,病粒率> 40%时,DO N含量> 2200μg/kg。#br#本研究采用卫生部食品卫生监督检验所建立的薄层色谱分析法测定样品中的DON含量,DON平均回收率为91.2%。     

Dissolved organic carbon and nitrogen in precipitation, throughfall and stemflow fromSchima superba andCunninghamia lanceolata plantations in subtropical China

Despite growing attention to the role of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in forest nutrient cycling, their monthly concentration dynamics in forest ecosystems, especially in subtropical forests only were little known. The goal of this study is to measure the concentrations and monthly dynamics of DOC and DON in precipitation, throughfall and stemflow for two plantations ofSchima superba (SS) and Chinese fir (Cunninghamia lanceolata, CF) in Jianou, Fujian, China. Samples of precipitation, throughfall and stemflow were collected on a rain event base from January 2002 to December 2002. Upon collection, all water samples were analyzed for DOC, NO₃ ⁻−N, NH₄ ⁺−N and total dissolved N (TDN). DON was calculated by subtracting NO₃ ⁻−N and NH₄ ⁺−N from TDN. The results showed that the precipitation had a mean DOC concentration of 1.7 mg·L⁻¹ and DON concentration of 0.13 mg·L⁻¹. The mean DOC and DON concentrations in throughfall were 11.2 and 0.24 mg·L⁻¹ in the SS and 10.3 and 0.19 mg·L⁻¹ in the CF respectively. Stemflow DOC and DON concentrations in the CF (19.1 and 0.66 mg·L⁻¹ respectively) were significantly higher than those in the SS (17.6 and 0.48 mg·L⁻¹ respectively). No clear monthly variation in precipitation DOC concentration was found in our study, while DON concentration in precipitation tended to be higher in summer or autumn. The monthly variations of DON concentrations were very similar in throughfall and stemflow at both forests, showing an increase at the beginning of the rainy season in March. In contrast, monthly changes of the DOC concentrations in throughfall of the SS and CF were different to those in stemflow. Throughfall DOC concentrations were higher from February to April, while relatively higher DOC concentrations in stemflow were found during September–November period. Foundation item: This study was supported by the Teaching and Research Award program for MOE P.R.C. (TRAPOYT). Biography: Guo Jian-fen (1977-), female, Ph. Doctor in College of Life Science, Xiamen University, Xiamen 361005, P.R. China. Responsible editor: Zhu Hong     

Correlations among Fusarium culmorum head blight resistance, fungal colonization and mycotoxin contents in winter rye

Fusarium culmorum head blight infections may lead to accumulation of toxic metabolites in winter rye grain. To estimate the correlation between resistance traits, fungal colonization and accumulation of deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON) and zea-ralenone (ZEA), 27 winter rye single-cross hybrids were artificially inoculated in 1992 and 1993. Resistance traits were head blight rating and grain weight of the inoculated relative to the non-inoculated plots. Fungal colonization was determined by the analysis of ergosterol (ERG) content in the grain. Head blight rating and relative grain yield showed a medium to high disease severity and ERG indicated a considerable fungal colonization of the kernels with a mean of 85 mg/kg in 1992 and 66 mg/kg in 1993. DON content among genotypes ranged from 0.7–28 mg/kg in 1992 and from 11 to 35 mg/kg in 1993. 3-AcDON and ZEA contents were low in both years with overall means of 1.1 and 0.09 mg/kg, respectively. Across both years, considerable genotypic variation was found for head blight rating, relative grain weight, and ERG content with medium to high heritabilities (0.6–0.7). For the mycotoxin contents, however, genotype-year interaction variance was the most important source of variation. The correlations between relative grain weight and DON, 3-AcDON, or ZEA were low in 1992 (r ～ 0.3), but considerably higher in 1993 (r ～ 0.7, P = 0.01). In contrast, correlation between relative grain weight and ERG was significant in both years (r ～ 0.5, P = 0.01). In F. culmorum head blight infections, DON, 3-AcDON and ZEA contents appear to be affected, at least partially, by different environmental factors than resistance traits and fungal colonization.     

Depolymerization and mineralization rates at 12 Mediterranean sites with varying soil N availability. A test for the Schimel and Bennett model

It has been suggested that the relative abundance of soil nitrogen forms should change along an N availability gradient. This model was originally described at a biome scale, and few studies have tested it at other scales. Moreover, none of them has examined whether changes in the relative rates of ammonification, nitrification and depolymerization rates also occurs. Our goal was to test whether these N transformation rates change along an N availability gradient which is likely to exist between forest, shrubs and grasses. We used three N availability indexes (total K₂SO₄-extractable N, ion exchange membrane N and the sum of N mineralization and depolymerization rates). Depolymerization dominated over mineralization in the two poorest plant communities, while ammonification and nitrification rates dominated in intermediate and nutrient rich plant communities respectively. These results confirm that the Schimel and Bennett model can be applied at a regional scale, and that N availability may be modulating not only the dominant N form, but also the relative abundance of a particular N transformation rate.     

Nitrogen Fractions in Arable Soils in Relation to Nitrogen Mineralization and Plant Uptake

Abstract

Nitrogen (N) as a major constituent of all plants is one of the most important nutrients. Minimizing input of mineral nitrogen fertilizer is needed to avoid harm to the environment. Optimal input of mineral nitrogen should take the nitrogen supply of the soil into account. Many different soil tests have been proposed for determining soil nitrogen availability. In this article we present a new approach that is based on the measurement of nitrate, ammonium, and dissolved organic nitrogen (DON) in a 0.01 M CaCl₂ soil extract. Eighteen agricultural soils, differing widely in the availability of nitrogen were used, fertilized and unfertilized. It is shown that the nitrogen uptake by maize plants (Zea Mays L.) in both “N‐fertilized” and “N‐unfertilized” soils as measured in a pot experiment can be described with a simple model using the measured nitrogen fractions in the extract. The main source of nitrogen uptake by the plants is the mineralized organic nitrogen during the growing period. It is shown that the initial measured DON fraction is a good indicator of the nitrogen mineralized during plant growth.     

链霉菌抗生物素蛋白—过氧化物酶连结法定位肝脏中脱氧雪腐镰刀菌烯醇的研究

脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON),又名呕吐毒素,是目前全球谷物污染最严重的真菌毒素之一。在所有的易感动物中,以猪最为敏感。本研究选用10头健康阉公猪,随机分为2组,染毒组和对照组,染毒组经乳静脉注射DON,注射剂量为75μg/kg体重,对照组经乳静脉注射生理盐水。注射完成后开始计时30 min后放血宰杀,迅速取肝脏,采用链霉菌抗生物素蛋白—过氧化物酶连接结(streptavidin-perosidase,SP)法定位肝组织中的DON。SP法定位结果显示,在染毒组肝门管区小叶间静脉的血管壁有DON的分布。本研究采用SP法定位DON在猪体内消化器官组织的分布情况,为毒素的残留研究提供依据。     

六棱大麦抗赤霉病QTL的定位(英文)

赤霉病是最严重的大麦病害之一。由于赤霉病抗性是受多基因控制的数量性状(QTL),并且一些表型性状也影响大麦赤霉病的抗病,如棱数、株高和抽穗期等,所以抗赤霉病大麦品种的选育十分困难。为了明确加拿大六棱大麦中赤霉病抗性以及相关性状的QTLs,本研究在4年中对93个家系的DH作图群体中赤霉病抗性、呕吐毒素(DON)含量、株高、抽穗期和成熟期等相关性状进行调查,并利用分子标记(444个DArT和26个SSR标记)构建的连锁图谱对QTL开展复合区间作图。结果表明,本研究共检测到4个影响赤霉病的QTLs,其中,2个主要的QTLs定位在3H和7H染色体上,它们的加性效应为-3.44和-3.69,分别解释14.1%和17.5%的表型差异,总共解释31.6%的赤霉病抗性差异;另外2个QTLs定位于7H染色体上,但二者同时也与DON含量显著相关。此外,在3H、5H和7H染色体上确定了5个影响株高的QTLs,在2H、4H、5H和7H上确定了4个影响抽穗期的QTLs。同时发现2个赤霉病抗性QTLs和1个DON累积QTL与控制株高的QTLs聚集重叠,1个赤霉病抗性QTL和抽穗期QTLs重叠。这些与赤霉病抗性、株高及抽穗期等农艺性状紧密连锁的分子标记可进一步用于有效提高抗赤霉病大麦品种的选育效率。