Simultaneous double labelling of routinely processed paraffin tissue sections using combined immunoperoxidase, immunofluorescence, and digital image editing

An innovative image editing system based on a sequential immunoperoxidase-immunofluorescence technique on routine histological sections is described. With this technique it is possible to identify different antigens in different cells, as well as co-localised antigens in the same cell. The method uses digital image editing to mix two independently captured images into one merged image. The technique was performed with indirect immunoperoxidase, followed by sequential indirect immunofluorescence, digital image acquisition and image editing. Multiple staining examples using anti-cytokeratin, anti-vimentin and anti-calbindin antibodies on canine skin and cerebellum, and feline pleural mesothelioma sections were performed in order to investigate the capabilities of the proposed technique. Our data demonstrated that this method can be easily used to assess multiple protein staining studies with minimum laboratory equipment, and that it allows a better structural visualisation of the tissue morphology compared to double immunofluorescence. Moreover, in contrast to double-immunoperoxidase, with this method it is possible to easily co-localise two different antigens in the same cell compartment.     

国产与进口预包装乳制品致敏原标签的对比分析研究

本研究对我国国产与进口乳制品的致敏原标识现状进行分析,同时对比我国和国外食品致敏原标签法规,针对我国致敏原标签管理中的问题提出相关建议。通过对比我国国产与进口乳制品产品的致敏原标识情况发现,国产与进口产品的致敏原标识率均较低;在致敏原的标识位置、标识用语以及标识内容强调方面,国产与进口乳制品均存在不足,其中致敏原标识位置在配料表下方的国产与进口乳制品分别占60.0%和55.6%;在致敏原标识用语方面,国外品牌更偏向使用"过敏"或"致敏"为引导词;在致敏原标识内容的强调方面,国内外只有2 个品牌通过字体加粗或改变字体颜色的方式对致敏原进行了强调。     

Labile and recalcitrant plant fractions are utilised by distinct microbial communities in soil: Independent of the presence of roots and mycorrhizal fungi

Plant inputs of organic material to soil are thought to be key determinants of microbial activity, community composition and processes. However, the identity of organisms utilising these chemically diverse inputs is not well understood. In this study, we applied tracer amounts of highly enriched, ¹³C-labelled plant tissue fractions (whole, insoluble and soluble) to soil cores that either allowed or prevented access to roots and mycorrhizal fungi. For all tissue fractions, C derived from the additions was detected rapidly (<2 h after additions) in soil respiration. The additions did not alter microbial community structure, but their fate was strongly dependent on the addition type. The mineralisation of the soluble fraction was the most rapid and was recovered predominantly in bacterial PLFA biomarkers. In contrast, the insoluble addition was mineralised more slowly and recovered in fungal biomarkers to a greater extent. The presence of roots and/or mycorrhizas did not significantly affect rates of mineralisation or the biological fate of additions. A second harvest indicated that the distribution of substrate-derived C within the microbial community was still distinct (i.e. dependent on the form of addition) after 49 d, but with accumulation of ¹³C within the enchytraeid biomass. The results indicate that under the conditions of this experiment, transfer of C between microbial groups is relatively slow, suggesting that the range of chemical forms of plant inputs are likely important in maintaining microbial community structure in soils.     

Fate of N and C from labelled plant material: Recovery in perennial ryegrass–clover mixtures and in pore water of the sward

The belowground C and N dynamics leading to organic and inorganic N leaching from perennial ryegrass–clover mixtures are not well understood. Based on the hypothesis that four different plant materials would degrade differently, a 16 months field experiment was conducted to determine (i) the source strength of labelled plant residues in dissolved inorganic N (DIN) and dissolved organic N (DON) in pore water from the plough layer, and (ii) the plant uptake of organically bound N. Litterbags containing ¹⁴C- and ¹⁵N-labelled ryegrass or clover roots or leaves were inserted into the sward of a ryegrass–clover mixture in early spring. The fate of the released ¹⁴C and ¹⁵N was monitored in harvested biomass, roots, soil, and pore water percolating from the plough layer. No evidence of plant uptake of dual-labelled organic compounds from the dual-labelled residues could be observed. N in pore water from the plough layer during autumn and winter had a constant content of dissolved organic N (DON) and an increasing content of dissolved inorganic N (DIN). A positive correlation between aboveground clover biomass harvested in the growth season and total-N in pore water indicated that decaying roots from the living clover could be a major source of the 10 kg N ha⁻¹ being lost with pore water during autumn and winter. The presence of ¹⁵N in pore water shifted from the DON fraction in autumn to the DIN fraction in late winter, with strong indications that ¹⁵N originated from the living ryegrass. However, ¹⁵N in pore water originating from plant residues only constituted 1.5% of the total dissolved N from the plough layer.     

Paddy System with a Hybrid Rice Enhances Cyanobacteria Nostoc and Increases N2 Fixation

Biological nitrogen(N) fixation(BNF) plays a significant role in maintaining soil fertility in paddy field ecosystems. Rice variety influences BNF, but how different rice varieties regulate BNF and associated diazotroph communities has not been quantified. Airtight,field-based ~(15)N_2-labelling growth chamber experiments were used to assess the BNF capacity of different rice varieties. In addition,both the 16 S rRNA and nifH genes were sequenced to assess the influence of different rice varieties on bacterial and diazotrophic communities in paddy soils. After subjecting a rice-soil system to 74 d of continuous airtight, field-based ~(15)N_2 labelling in pots in a growth chamber, the amounts of fixed N were 22.3 and 38.9 kg ha~(-1) in inbred japonica(W23) and hybrid indica(IIY) rice cultivars planted in the rice-soil systems, respectively, and only 1%–2.5% of the fixed N was allocated to the rice plants and weeds. A greater abundance of diazotrophs was found in the surface soil(0–1 cm) under IIY than under W23. Sequencing of the 16 S rRNA gene showed significantly greater abundances of the cyanobacterial genera Nostoc, Anabaena, and Cylindrospermum under IIY than under W23.Sequencing of the nifH gene also showed a significantly greater abundance of Nostoc under IIY than under W23. These results indicate that the hybrid rice cultivar(IIY) promoted BNF to a greater extent than the inbred rice cultivar(W23) and that the increase in BNF might have been due to the enhanced heterocystous cyanobacteria Nostoc.     

白色念珠菌和鼠伤寒沙门氏菌的荧光标记及其对细胞粘附作用的影响

比较了几种荧光染料标记白色念殊菌和鼠伤寒沙门氏菌的效果及其对病菌生长和与Hela细胞粘附能力的影响，旨在为建立简便有效的荧光标记方法奠定基础。将2种致病菌分别在添加了罗丹明B、荧光素Na盐或吖啶橙的LB培养液，37℃条件下培养1d，结果发现这2种致病菌都可以被荧光素Na盐标记，鼠伤寒沙门氏菌还可以被罗丹明B标记，但这2种致病菌都不能在吖啶橙中生长。测定致病菌荧光强度发现，随罗丹明B标记剂量的增加，致病菌荧光强度增强，而荧光素Na盐小剂量组处理的致病菌荧光强度最强。此外还发现，致病菌与Hela细胞的粘附不受荧光标记的影响。     

欧盟转基因食品溯源管理体系

食品的可追溯性是转基因食品安全的关注重点之一,欧盟通过法规（EC）NO 1830/2003建立了转基因食品可追溯性管理框架,并通过法规（EC）1829/2003来规范转基因食品的授权和投放市场后的监督、以及转基因食品的标签管理;通过唯一标识系统法规（EC） 65/2004实现转基因食品的溯源管理,整个溯源体系体现了欧盟在食品安全管理中“从农场到餐桌”的管理理念。文章系统介绍了欧盟转基因食品溯源管理体系,为我国转基因食品的溯源及其管理提供参考。     

食品标识国内外法规标准比较研究

食品标识作为记录食品综合信息的载体,是食品内在信息最直观的体现,也是食品安全管理的主要内容。各个国家/组织在食品标识管理中都制定了严格的法规标准,且存在异同点。本文通过收集、整理国内外现行食品标识法规标准,对比分析中国与CAC、欧盟、美国和澳新食品标识法规标准的差异,包括食品标识内容以及主要差异的比较,为完善我国食品标识法规标准提供有价值的参考。     

The determination of ‘L’ values by discrete and integrated sampling procedures

Abstract

A discrete and an integrated sampling procedure were used to determine ‘ L ‘ values for maize plants grown in a soil. In the discrete procedure a plant was grown in a sand culture labelled with ³³P solution and then transferred in a soil which was labelled with ³²P. In the integrated sampling procedure plants were grown entirely in a P label led soil.

The discrete procedure permits point of time observation so that changes in the equilibrium between solution and surface P and mineralization rates can be monitored.