Nitrogen-15 Leaching Under Temporarily Weedy Maize

Abstract

In pot experiments the effect of a temporary infestation of maize by Chenopodium album L. on water and nitrogen leaching after a simulated strong rainfall was tested for a silty loam and a loamy sand. The results show that the leaching of ¹⁵N under the initial stage of maize can be reduced considerably by a temporarily weed infestation. Neither yield of maize nor uptake of nitrogen until corn maturity were reduced on both a silty loam and a loamy sand.     

Evaluation of the potential of Potamogeton crispus and Myriophyllum spicatum on phytoremediation of atrazine

Atrazine is one of the most frequently detected pesticides and poses a great risk to humans and the environment. In this study, the effects of two submerged macrophytes, Potamogeton crispus and Myriophyllum spicatum, on phytoremediation of atrazine were evaluated. The results showed that atrazine decayed faster in the pots where these two plants were cultivated than that of the control without the plants during the 60-day course of the experiment. Metabolite analyses of atrazine indicated that atrazine was mainly converted to diaminochlorotriazine and hydroxyatrazine. Dissipation kinetics and risk assessment of atrazine showed that atrazine was degraded rather fast in maize and generally safe for human consumption at the recommended high dosage of atrazine. The maximum permissible intake (MPI) for atrazine was calculated to be 0.23 μg/person/day for a child and 0.72 μg/person/day for an adult. However, due to the large-scale application of atrazine over the years, the atrazine residue still poses a great threat to the environment. By using submerged macrophytes M. spicatum and P. crispus, atrazine could be absorbed from the sediment, hence remediating contaminated sediment and water. This study established a protocol for evaluating submerged plants in absorption or phytoremediation of pesticides.     

酶联免疫分析法探测Cry1Ab蛋白在不同介质中的构象变化

采用酶联免疫分析（ELISA）方法,根据构象变化后的蛋白与抗体结合能力下降从而导致ELISA测定值降低的原理,探测了转cry1Ab基因水稻表达的Cry1Ab蛋白在不同溶液介质中的热致构象变化行为,以及不同有机溶剂及溶液pH值对该蛋白构象变化的影响程度。实验表明,Cry1Ab蛋白在不同条件下的构象变化程度可以灵敏地通过ELISA方法检测。在不同的介质中,CrylAb蛋白的热致构象变化程度不同。在Na2SO4介质中,该蛋白具有较高的热稳定性;SDS的存在,可以促进该蛋白的构象变化。常温下,25％（V／V）的有机溶剂乙腈、异丙醇、甲醇、乙醇均能使该蛋白的构象发生转变,其中以乙腈最为显著。醇类溶剂对Cry1Ab蛋白的构象影响程度随疏水性增大而增大;溶液pH值也对该蛋白的构象变化产生影响。pH在8-10之间,该蛋白构象能保持稳定;酸或过碱性的溶液均能使蛋白构象偏离原始状态,从而引起ELISA测定值的降低。另外,腐殖酸能在一定时间内保持Cry1Ab蛋白构象的稳定性。     

GENETIC ENGINEERING OF TOBACCO PLANTS WITH CMV RESISTANCE CONFERRED BY MONOMER cDNA OF SATELLITE RNA

The synthesized full-length cDNA to CMV satellite RNA-1 was integrated into plant expression vector RoKII with a CaMV 35S promoter. Infected by Agrobacterium tumefaciens harbouring the recombinant plasmid. The tobacco leaf discs (the G-140 variety which is widely cultivated in China) were regenerated into plants. After being inoculated with virulent strain CMV, most of the transgenic plants expressed satellite RNA at high levels and developed a much milder symptom than the untransformed ones.Basically in accordance with Mendel's law of segregation, the novel tobacco pure line engineered with viral resistance was screened out. The secondary generation transgenic plants still maintained high level satellite RNA expression and the resistance to CMV.     

玉米大斑病抗性基因ht2的原位杂交物理定位

通过对与玉米大斑病（Ｈｅｌｍｉｎｔｈｏｓｐｏｒｉｕｍｔｕｒｃｉｃｕｍ）抗性基因ｈｔ２紧密连锁的２个玉米ＲＦＬＰ分子标记ｂｎｌ１２．３０和ｕｍｃ９３的染色体原位杂交定位，推断了大斑病抗性基因ｈｔ２的物理位置．ｂｎｌ１２．３０和ｕｍｃ９３在遗传图中位于第八连锁群上，它们的探针分别同时与第三和八染色体进行了杂交，平均信号检出率为１２．１３％；它们在第八号染色体长臂上杂交信号与着丝粒的百分距离分别是３３．３０±１．４１和３４．４７±２．７５，在第三号染色体长臂上杂交信号与着丝粒的百分距离分别是５１．４１±２．７５和５６．５４±２．９４．基因ｈｔ２在遗传图上位于第八连锁群的ｂｎｌ１２．３０和ｕｍｃ９３之间，因此，ｈｔ２在染色体上的物理位置应为第八号染色体长臂，百分距离为３３．３０和３４．４７之间．在第三号染色体长臂上两个供试ＲＦＬＰ标记的分布区之间也可能有ｈｔ２的同源顺序．     

Incidence of Fusarium Mycotoxins in Wheat and Maize from Albania

In this study, ten Fusarium toxins were analysed in wheat and maize commodities from Albania. In total, 71 samples of wheat and 45 samples of maize were collected from different producing regions. The analytical procedure consisted of a simple one-step sample extraction followed by the determination of toxins using liquid chromatography coupled with tandem mass spectrometry. Fusarium toxins were found in 23% of the analysed wheat samples and in 78% of maize samples. In maize samples, most often fumonisins B₁ (FB1) and B₂ (FB2) were found. They were present in 76% of samples. They were detected in all positive samples except in one with concentrations ranging from 59.9 to 16,970 μg/kg. The sum of FB1 and FB2 exceeded the EU maximum permitted level (4000 μg/kg) in 31% of maize samples. In wheat samples, the only detected Fusarium mycotoxin was deoxynivalenol (DON), present in 23% of samples. In one sample with the concentration of 1916 μg/kg, the EU maximum permitted level (1250 μg/kg) was exceeded. This is the first report on the presence of Fusarium toxins in wheat and maize grains cultivated in Albania.     

Nicotiana langsdorffii wild type and genetically modified exposed to chemical and physical stress: changes in element content

The concentrations of 19 elements in wild and genetically modified Nicotiana langsdorffii (N. langsdorffii) exposed to Chromium (VI) and to water deficit were determined and compared to provide new information about their response to abiotic stress.

Genetic modifications by GR and RolC genes (encoding for the rat glucocorticoid receptor and for Agrobacterium rhizogenes RolC, respectively) were investigated because they induce significant, but only partially known changes in the plant response to stress.

Simultaneous determination of Al, As, Ba, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, Mg, Mn, Na, Pb, Rb, Sr, V and Zn was carried out by ICP-MS equipped with a collision/reaction cell (ICP-ORS-MS). The methodology was optimised by testing the grinding, homogenisation, digestion and analysis procedures, to reduce the uncertainty of the experimental results and to identify statistically significant differences between nine sample pools, for a total of 75 samples. The quality control procedure was carried out by blank control and by evaluating the detection limits and repeatability. Trueness was assessed by analysing certified reference material, NIST 1573a.

Significant differences were observed in the uptake and accumulation of several elements in the wild-type N. langsdorffii samples, either with respect to the plants submitted to water deficit and exposure to Cr(VI) or with respect to the genetically modified plants. The differences were highlighted by principal component analysis (PCA). The analysis of the element content of the whole plant, combined with the data found in the literature, allows us to hypothesise effects on the metabolic mechanism controlling the uptake and translocation of elements inside the vegetal organism. Because genetic and chemical stress decreases the nutrient concentration in the whole plant, we can say that the uptake at root level is affected. The increase in concentration of elements such as As, Sr and Al indicates a decreased selectivity in the uptake of potentially toxic elements and, consequently, highlights the effects on the plant’s metabolic processes.     

Morphogenetic and chemical stability of long-term maintained Agrobacterium-mediated transgenic Catharanthus roseus plants

Transgenic Catharanthus roseus plants (transgenic Dhawal [DT] and transgenic Nirmal [NT]) obtained from the Agrobacterium tumefaciens and Agrobacteriumrhizognenes-mediated transformations, respectively, have been maintained in vitro for 5 years. Plants were studied at regular intervals for various parameters such as plant height, leaf size, multiplication rate, alkaloid profile and presence of marker genes. DT plant gradually lost the GUS gene expression and it was not detected in the fifth year while NT plant demonstrated the presence of genes rolA, rolB and rolC even in the fifth year, indicating the more stable nature of Ri transgene. Vindoline content in the DT was two times more than in non-transformed control plants. Alkaloid and tryptophan profiles were almost constant during the 5 years. The cluster analysis revealed that the DT plant is more close to the control Nirmal plant followed by NT plant.     

Electrosprayed maize starch and its constituents (amylose and amylopectin) nanoparticles

Starch consists of amylose and amylopectin. Properties such as being natural and highly hygroscopic as well as biodegradability have opened a considerable range of applications for amylose, amylopectin and starch. The performance of particles is highly dependent on their size which in turn determines the specific surface area. This work studies the application of electrospraying to fabricate maize starch and its constituents: amylose and amylopectin nanoparticles. This study showed that electrospraying technique is capable of producing amylose, amylopectin and starch nanopowder with an average particle size around 100 nm. FTIR analysis showed no reaction or interaction occurring in amylose, amylopectin and starch nanoparticle compared with their natural form. Basically, lower concentration, lower viscosity and lower surface tension of the electrospraying solution as well as higher nozzle–collector distance, higher voltage and lower feed rate lead to smaller nanoparticle size. Copyright © 2015 John Wiley & Sons, Ltd.     

RAPD技术在东北地区玉米品种鉴别上的应用

应用现代分子生物学RAPD技术,对吉林省主推6个玉米杂交种及其父母本的指纹图谱进行鉴别.在30个随机引物中选出扩增效果明显、特异性高的引物R1和R2并对18份材料进行基因图谱的分析,图谱差异显著、易于区分,说明RAPD技术可用于玉米品种鉴定和纯度鉴定.