Partitioning into maize grain N fractions of N absorbed through the roots before and after pollination

The abundance of N in various fractions in maize (Zea mays L.) grain was compared in two genotypes, a normal hybrid (Pioneer 3369A) and its opaque-2 (o-2) counterpart (L3369). Plants were grown in the greenhouse in sand cultures irrigated daily with nutrient solutions containing 3.75mM N as NO₃ ion. At anthesis the plant cultures were divided into sets, one set continuing to be irrigated with the same solution, but with ¹⁵N added, and the other set irrigated with a solution of the same composition except that the N was omitted. The plants were sampled at 12, 24 and 36 days after pollination. Post-anthesis N nutrition affected the composition of the vegetative growth but had no effect during the sampling period on yields or amounts of N in the grain. At 12 days post-pollination there were no differences between the two genotypes in N partitioning, with about 50% of the N present as nonprotein N (NPN). At 24 and 36 days over 75% more N was present as zein in the normal genotype as in the 0-2, while the latter contained a much higher proportion of N as NPN. The albumin-globulin and glutelin fractions were slightly greater in the o-2. The N absorbed after pollination was partitioned among the grain protein fractions similarly to N absorbed prior to pollination. The nature of the NPN fraction needs to be considered in evaluating effects on crop quality of an elevated N supply.     

广义Green关系N、A与广义理想N(a)

定义了广义关系N和A以及主N理想N(a) ,并证明了N J A ,进而加细了Green关系 ,且给出了关系结构 :　　　　　　　　　　　　 　N　 　　　　B　　　　　　J A　　　　　　　 L　　　　 H　　 D 　　　　　　　 R     

两种蛋白酶水解大豆分离蛋白的特性研究

使用碱性蛋白酶Alcalase2.4L(EC3.4.21.62)和中性蛋白酶Protease N(IUB3.4.24.28)在间歇式反应器和酶膜反应器中水解大豆分离蛋白(SPI),并对其水解特性进行了研究。结果表明:Protease N具有较高的蛋白酶水解活力,最适作用温度低并且稳定性好,水解过程中易受产物抑制;两种酶水解产物的相对分子质量均小于10000Da,游离氨基酸含量较低;Protease N更适合用于酶膜反应器中水解SPI。     

利用中空纤维更新液膜技术从稀溶液中提取柠檬酸

采用一种新型的液膜技术——中空纤维更新液膜技术(HFRLM),以30%N235(三辛/癸基叔胺)/20%正辛醇/煤油为液膜相,NaOH溶液为反萃剂,从稀溶液中提取柠檬酸。结果表明,中空纤维更新液膜技术可实现对柠檬酸的同步分离和浓缩,提取率达98%以上,浓缩倍数可达9倍以上,表明该技术在柠檬酸稀溶液提取方面具有广阔的应用前景。     

糖厂滤泥中几种元素的分析

利用原子吸收光谱法、分光光度法、容量分析等方法,对原糖加工过程中产生的滤泥进行化学分析,以进一步提高滤泥的废物利用。     

不同施肥方式对植烟土壤有效氮、烟株氮累积量和速率的影响

在鄂西南植烟土壤上研究了不同施肥方式对土壤有效氮、烟株氮累积量以及氮累积速率的影响。结果显示,在不栽烟情况下,施肥后40 d内肥料养分损失完毕,60 d后土壤有机氮矿化量高于有效氮损失量,土壤有效氮出现净累积;全生育期覆膜方式下移栽后63 d内化肥处理(D)土壤有效氮明显高于有机无机配施处理(G),烟株氮累积和土壤有效氮下降成显著负相关,且G处理相关程度(-0.935)高于D处理(-0.661);前期覆膜团棵揭膜方式下,移栽后42 d内化肥处理(E)土壤有效氮明显高于有机无机配施处理(F),烟株氮累积量和累积速率F处理均高于E处理;提前施肥起垄方式下,化肥处理(I)和有机无机配施处理(H)土壤有效氮变化基本一致且烟株氮累积量和累积速率H处理均高于I处理。不论何种施肥方式,移栽后前期化肥处理土壤有效氮含量明显高于有机无机配施处理,而烟株氮累积则相反,证明施用有机肥可以使烟株对氮素吸收累积高峰提前,且提高烟株氮累积量和氮累积速率。提前施肥可明显弱化不同肥料处理之间土壤有效氮的差异。     

超声波法混合蛋白酶水解酪蛋白制备酪蛋白磷酸肽的研究

探索了超声波法利用胰蛋白酶与碱性内切酶合理配比水解酪蛋白制备高得率、低N／P的酪蛋白磷酸肽的最佳工艺条件：超声波功S200W，超声时间15min，底物质量浓度100g／L，酶与底物比0．5％，pH值为8，胰蛋白酶与碱性内切酶1：1，温度为50℃。     

Nicolas Appert: Inventor and Manufacturer

This article summarizes the life and work of Nicolas Appert, a famous French inventor and manufacturer. He devoted his life to the empirical development of the appertization process. His main objective was to offer to consumers, especially seamen, preserved foodstuff still having the appearance and properties of fresh fruit and vegetables. The inventor was in debt most of his life even though his discovery gave birth to a flourishing industry. This paper focuses on the main events in Appert's life and on the appertization process as described by Appert himself.     

Relative proportion of inorganic and total nitrogen in broiler litter as determined by various methods

We report relative proportion of inorganic N in broiler litter and compare the regular Kjeldahl method with three of its modifications (the salicylic acid–thiosulfate modification, the Devarda's alloy modification, and the potassium permanganate–reduced iron modification), and with a Leco‐combustion (CHN‐600) method for the degree to which they include NO₃^?‐N and NO₂^?‐N in broiler litter analysis. Inorganic N in the litter (<500 µm) was determined after extraction with 2 mol L^?1 KCl. NH₄⁺‐N and (NO₃^? + NO₂^?)‐N in the filtrate were analysed by steam distillation while NO₂^?‐N was determined by a modified Griess–Ilosvay colorimetric method. For the determination of total N, 25 mg broiler litter (<1000 µm) was digested according to four semi‐micro‐Kjeldahl methods in a 100‐mL Pyrex Kjeldahl flask using an electrically heated six‐flask micro‐Kjeldahl digestion rack. Ammonium‐N in the digest was determined by steam distillation. The results showed that inorganic N represents a small portion of total N in the samples. Ammonium is the most dominant inorganic N (1.61–5.39 g kg^?1) in the samples; it represents between 42 and 94% of the inorganic N. The (NO₃^? + NO₂^?)‐N contents varied between 0.19 and 5.56 g kg^?1 while NO₂^?‐N contents in the samples were negligible (<0.6 g kg^?1). The regular Kjeldahl method and its modifications recovered all the NH₄⁺‐N added but recovery of added NO₂^?‐N and NO₃^?‐N varied considerably with the methods. The Devarda's alloy and the potassium permanganate methods showed the highest N measurements while the Leco‐combustion showed the lowest N measurements. Copyright © 2006 Society of Chemical Industry     

Profiles of free amino acids in grapes of grafted Chardonnay grapevines

Chardonnay grapes from a rootstock trial in the Murray Valley region of South Australia were sampled for two seasons and concentrations of free amino acids in grape extract ('juice') were determined. The lowest concentrations of free assimilable amino-N were measured in Chardonnay grapes from vines on 140 Ruggeri and 101–14 rootstocks, and the highest concentrations were in grapes from vines on their own roots, Schwarzmann and K51–40. Free assimilable amino-N concentrations were sufficient to sustain fermentation through to completion. Arginine concentrations were generally too low to expect significant concentrations of urea in the wine. Amino-S concentrations were much lower and varied less than amino-N concentrations. The effect of any particular rootstock on the concentration of total free amino acids in Chardonnay grape 'juice' did not appear to be related to the known effects of those rootstocks on the NO₃-N status of petioles at flowering. The concentrations of leucine, iso-leucine, valine, threonine, tyrosine and phenylalanine were generally higher in Chardonnay grapes grafted onto K51–40 in comparison to grapes from Chardonnay vines grafted on the other rootstocks. Any of these amino acids may be associated with the presence of specific higher alcohols in wine.     

Influence of N doses and form on ¹⁵N natural abundance of pepper plants: considerations for using δ¹⁵N values as indicator of N source

BACKGROUND: The aim of this study was to ascertain the effect of the N form (NO₃^?, NH₄⁺ and organic N) and N concentration on plant isotopic fractionation and on the contribution of the different N sources to the plant N budget, in order to evaluate the feasibility of using plant δ¹⁵N values for discriminating between conventional and organic crops. To this end, different N concentrations (applied as NO₃^?), N forms (NO₃^? versus NH₄⁺), and increasing NO₃^? applications to an organic N‐based fertilization regime were studied. RESULTS: When using NO₃^? as N source, intra‐plant fractionation was significant and tended to increase when NO₃^? concentration increased in the root medium. However, negligible net isotopic fractionation was observed when comparing theoretical and measured plant δ¹⁵N values. On the other hand, when plants are fertilized with a mixture of NO₃^? and NH₄⁺, differences in uptake patterns for both salts could result in variation in plant δ¹⁵N regarding to the expected value. Finally, the application of NO₃^? to plants was detected when it was combined with high levels of organic N sources, from 99:1 organic:inorganic N ratio. CONCLUSION: Under certain conditions and following some considerations concerning sampling, δ¹⁵N values can be considered to be a potential tool to guarantee the authenticity of organic products. Copyright © 2011 Society of Chemical Industry     

转马铃薯Y病毒复制酶基因烟草的获得及抗病性分析

重组克隆ＤＮＡ用ＫｐｎＩ／ＢａｍＨＩ双酶切得到马铃薯Ｙ病毒ＮＩｂ基因，将其插入质粒ｐＲＯＫ２相应切点中构成植物表达载体。用重组质粒ｐＲＯＫ２转化农杆菌（Ａｇｒｏｂａｃｔｅｒｉｕｍｔｕｍｅｆａ－ｃｉｅｎｓ）ＬＢＡ４４０４菌株，叶盘法将ＮＩｂ基因转入烤烟品种ＮＣ８９的染色体，获得抗卡那霉素的转化再生植株。经抗性筛选、ＰＣＲ检测、无性扩繁和大量重复抗病鉴定，结果表明，转化烟草植株ＤＮＡ中整合了外源目的基因，且表现抵抗２０μｇ／ｍｌＰＶＹＮ的侵染，ＥＬＩＳＡ分析认为抗性植株无病毒累积，初步筛选出对ＰＶＹＮ侵染具有较高抗性的转基因烟草植株。     

外源碳添加对植烟土壤氮素转化及N2O排放的影响

为探寻有效调控烤烟生长后期植烟土壤氮素水平的措施,采用室内培养的试验方法,研究了葡萄糖、木屑及二者混合物对植烟土壤氮素转化及N₂O排放的影响。试验设5个添加等量碳（纯碳3000 mg/kg）处理及1个对照：G1S0,葡萄糖：木屑=1：0（以纯碳计,下同）;G2S1,葡萄糖：木屑=2：1;G1S1,葡萄糖：木屑=1：1;G1S2,葡萄糖：木屑=1：2;G0S1,葡萄糖：木屑=0：1;CK,不添加外源碳。结果表明,在培养1 d后,与对照处理相比,G1S0、G2S1、G1S1、G1S2处理的无机氮含量分别降低了51.71、61.78、62.33、62.46 mg/kg,而G0S1处理的无机氮含量却增加了4.12 mg/kg;G1S0,G2S1,G1S1,G1S2和G0S1处理的无机氮含量分别在培养7,14,14,14和28 d后达到最小值后呈不断增大的趋势。在培养结束时,与对照处理相比,添加碳源处理的无机氮降低量为96.80~148.10 mg/kg;除G0S1外,添加碳源处理较CK处理显著增加了CO₂和N₂O累积排放量（p<0.05）。可见,添加葡萄糖、木屑及其混合物能够显著降低土壤中无机氮含量（p<0.05）;葡萄糖与木屑混施较单施木屑可以加快微生物对氮素的固持并增强固持强度,较单施葡萄糖能够延长微生物对氮素的固持时间;添加外源碳增强了土壤微生物活性,同时也刺激了N₂O排放。综合来看,葡萄糖和木屑混施降低无机氮含量的效果最好。因此,添加外源碳可作为一种调控植烟土壤氮素水平的措施。     

Application of foliar urea to grapevines: productivity and flavour components of grapes

Urea is a non-electrically charged nitrogen (N) molecule suitable for foliar application, since it easily penetrates the epicuticular waxes and the cutin layer of leaves. Several field trials have been conducted to understand how foliar application of urea to grapevines may affect yield and grape composition compared to other N fertilisers. The effectiveness of foliar application of urea to change the flavour components of grapes depends on the N status of the grapevines related to crop load and the timing of the foliar application, which could also play a key role in basal bud fertility and stored N reserves. The application of foliar urea to grapevines may affect the concentration of N, volatile compounds, and phenolic substances in grapes without influencing yield and its components in the short term. During alcoholic fermentation, grape N concentration favours the production of non-volatile and volatile compounds that affect wine attributes, aroma, bitterness, and astringency. Other N-compounds such as biogenic amines may also be formed in wines which can be toxic to the consumer. Gene expression related to grapevine N metabolism and the identification of putative chemical markers in red and white wines after foliar N application deserves further investigation. This review aimed to evaluate the factors involved in N uptake by leaves after foliar urea fertilisation, to summarise effects on grapevine yield components and grape composition and to provide also research options for future studies in this area.     

M-line protein: Presence of two non-equivalent high molecular weight components

M-line enriched protein preparations were prepared from glycerated rabbit muscle myofibrils by means of three alternate procedures and analysed with SDS-polyacrylamide gel electrophoresis. A doublet corresponding to polypeptides with molecular weights of 193,000 and 182,000 was obtained in a ratio of2:3, respectively. The two bands are evident in SDS-gels of purified myofibrils, indicating that the proteins represent intrinsic M-line structural peptides. Transmission electron micrographs of the extracted myofibrils confirmed the effectiveness of the extraction procedures for removing M-line proteins. The possible significance of the M-line proteins to meat science is discussed.     

Effect of drought and irrigation on the fate of nitrogen applied to cut permanent grass swards in lysimeters: Nitrogen balance sheet and the effect of sward destruction and ploughing on nitrogen mineralisation

Fuor years after ¹⁵N labelled fertiliser nitrogen (as Ca(NO₃)₂ and equivalent to 400 kg N ha^?1) was applied to permanent grass swards growing in lysimeter monoliths, approximately one-quarter remained immobilised in soil organic matter. In the intervening years similar but non-labelled applications were made. Although differing rainfall regimes applied during the experiment had significantly affected nitrogen uptake by plants and nitrate loss in drainage, they caused no significant effect on the tracer nitrogen remaining in the soil, the ranges were 85–97 kg N ha^?1 and 79–94 kg N ha^?1 respectively for the 135 cm deep clay and silt loam soil monoliths. Labelled nitrogen unaccounted for in crop, drainage or soil was presumed to have been denitrified. These losses averaged 62 and 49 kg N ha^?1 on the clay and silt loam soils respectively; again the differing rainfall regimes caused no significant differences. The ratio between estimates of labelled nitrogen denitrified and of annual nitroux oxide loss was approximately 9:1 for both soils. The conversion from permanent grass to winter wheat in autumn 1981, involving killing and then burying the sward, resulted in no pronounced increase in net mineralisation of labelled nitrogen. However, the balance between crop uptake and the quantity leached did change. Labelled nitrogen assimilated was less for the wheat (growing without addition of fertiliser nitrogen) than for the grass in its last year, and the quantity leached was considerably greater than under grass swards that were supplied with an average rainfall distribution. Following the first wheat harvest total nitrogen leached averaged 51 and 44 kg N ha^?1 on the clay and silt loam soils respectively. Rates of nitrous oxide emissions during the autumn following sward destruction were greater than in earlier years, but this enhanced loss was of short duration. The crop clearly benefited from the succession of nitrogen applications made to grass, as grain yield and total nitrogen uptake exceeded 7 t ha^?1 and 120 kg N ha^?1 respectively on both soils. These quantities exceed the national averages for winter wheat and are also considerably greater than for crops from lysimeters which received no nitrogen fertiliser throughout the experiment.     

N,N,N-trimethyl chitosan as an efficient antibacterial agent for polypropylene and polylactide nonwovens

The paper presents a method of depositing N,N,N-trimethyl chitosan (TMC) layers onto polypropylene and polylactide nonwovens. A two-step modification procedure is applied: first, grafting the nonwovens with acrylic acid and next layer-by-layer deposition. Turbidimetric measurements confirm the creation of polycomplexes between grafted poly(acrylic acid) and deposited TMC. The created material structure is evaluated using gravimetric analysis, reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy measurements and pH-metric titration. The modified material exhibits good antibacterial properties against Gram-positive bacteria Staphylococcus aureus.     

Quality of white cabbage yield and potential risk of ground water nitrogen pollution,as affected by nitrogen fertilisation and irrigation practices

BACKGROUND: The effect of different fertilisation (broadcast solid NPK application and fertigation with water‐soluble fertiliser) and irrigation practices (sprinkler and drip irrigation) on yield, the nitrate content in cabbage (Brassica oleracea var. capitata L.) and the cabbage N uptake was detected, in order to assess the potential risk for N losses, by cultivation on sandy–loam soil. The N rate applied on the plots was 200 kg N ha^?1. RESULTS: The highest yield (93 t ha^?1) and nitrate content (1256 mg kg^?1 DW) were found with treatments using broadcast fertilisation and sprinkler irrigation. On those plots the negative N balance (?30 kg N ha^?1) was recorded, which comes mainly from the highest crop N uptake (234 kg N ha^?1) indicating the lowest potential for N losses. CONCLUSION: In terms of yield quality and the potential risk for N losses, broadcast fertilisation combined with sprinkler irrigation proved to be the most effective combination among the tested practices under the given experimental conditions. The importance of adequate irrigation is also evident, namely in plots on which 50% drip irrigation was applied, the lowest yield was detected and according to the positive N balance, a higher potential for N losses is expected. Copyright © 2011 Society of Chemical Industry