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.     

Pre- and post-embedding immunogold labeling and electron microscopy in plant host tissues of three antigenically unrelated MLOs: primula yellows,tomato big bud and bermudagrass white leaf

Methods are described for pre- and post-embedding immunogold labeling of mycoplasmalike organisms (MLOs) in thin sections of infected plants. Antisera against primula yellows (PY), tomato big bud (TBB) and bermudagrass white leaf (BGWL) MLOs, and a monoclonal antibody (mab) against PY were tested with the three serologically unrelated MLOs. Labeling was specific for each MLO and was localized to the outer surface of the MLOs. The antisera performed well in both pre- and post-embedding experiments; the mab reacted well in pre-embedding conditions but gave no labeling with post-embedding. Glutaraldehyde fixation reduced levels of labeling in post-embedding conditions. The results show that these techniques can be used to differentiate MLOs reliably, and extend the usefulness of electron microscopy in this area.     

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。     

免疫胶体金法和免疫单扩散法检测牛初乳中IgG含量的比较研究

建立了检测牛初乳中免疫球蛋白(IgG)含量的免疫胶体金法,并与常用的免疫单扩散法进行了比较。结果表明:免疫胶体金法灵敏度为200μg/mL,操作简单快速,不需要特殊仪器和设备,适合现场的快速检测。单扩散法灵敏度较高,约为10~20μg/mL,但试验步骤较繁琐,单扩散需要恒定的时间、温度等条件,适合于实验室的精细测定。2种方法可结合使用,从而在保证检测灵敏度和特异性的前提下,大大提高检测速度。     

Chlorocholine chloride application effects on photosynthetic capacity and photoassimilates partitioning in potato (Solanum tuberosum L.)

Treatment of potato (Solanum tuberosum L.) with chlorocholine chloride (CCC) applied twice as a foliar spray 25 and 30 days after planting has shown to decrease shoot and stolon growth but increase tuber yield. However, the regulatory role of CCC on translocation of recently fixed photoassimilates into different parts of potato plants has not been fully illustrated. In this study, ¹⁴C-isotope labelling technique was used to estimate the photosynthetic capacity and photoassimilate partitioning among leaves, stems, roots + stolons, and tubers of potted potatoes treated with 1.5 g l⁻¹ CCC. CCC treatment significantly increased tuber dry mass but reduced leaf dry mass. CCC-treated leaves had significantly higher chlorophyll and carotenoid contents and assimilated 22.0% more ¹⁴CO₂ per leaf dry mass than the controls. Compared with the control, CCC treatment reduced the translocation of ¹⁴C-photoassimilates into leaves, stems and roots + stolons but increased that into tubers. CCC-treated leaves exported 14.6% more ¹⁴C-photoassimilates into other parts of the plants. In addition, CCC treatment reduced ¹⁴C-soluble sugar and ¹⁴C-starch accumulation in leaves and stems but enhanced them in tubers and roots + stolons. Collectively, the results indicate that CCC treatment significantly improves the photosynthetic capacity of potato leaves and promotes photoassimilates partitioning into tubers thereby enhancing tuber growth.     

生物质炭引起的土壤碳激发效应与土壤理化特性的相关性

生物质炭添加到土壤中将引发不同的激发效应,然而生物质炭激发效应与土壤性质之间的关系还不明确.将等碳量的13C稳定性同位素标记的小麦秸秆及其制成的生物质炭分别添加到4种不同性质的土壤中,室内培养1年,测定生物质炭及秸秆中碳元素在不同土壤中的降解量及其对土壤原有机碳的激发效应量.结果表明:生物质炭在黑土水稻土以及下位砂姜土...     

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.     

Photosynthesis is Reduced,and Seeds Fail to Set and Fill at Similar Soil Water Contents in Grass Pea (Lathyrus sativus L.) Subjected to Terminal Drought

Grass pea (Lathyrus sativus L.) is an indeterminate grain legume considered adapted to dry environments, but the mechanisms of its adaptation are not well understood. Grass pea plants were exposed to terminal drought from podding, and the development of water deficit was measured together with its effects on leaf photosynthesis, stomatal conductance, carbon remobilisation to the seeds, flower production and abortion, pod production and abortion, seed set, seed growth and the neurotoxin β‐N‐oxalyl‐L‐a, β‐diaminopropionic acid (β‐ODAP) concentration. Predawn leaf water potential (Ψ_leaf), stomatal conductance (gs), rate of leaf photosynthesis (Pn), flower production, pod production, filled pod number, seed number, seed size and yield decreased, while flower abortion, pod abortion and seed abortion increased, and the concentration of β‐ODAP was unchanged under terminal drought conditions. gs and Pn began to decrease at a higher plant‐available soil water content (PAWC) (67.2 ± 2.3 % and 62.9 ± 2.3 %) than Ψ_leaf (43.7 ± 1.1 %). Flowers and pods ceased being produced only when the PAWC decreased below 40.1 ± 4.6 % and 35.3 ± 3.0 %, respectively, but seed set and seed growth ceased when PAWC decreased below 55.5 ± 1.6 % and 58.0 ± 3.7 %, respectively. The mobilization of ¹³C labelled assimilates from the stems was greater under terminal drought than under well‐watered conditions, but the transfer to the seed was small. We conclude that seed set and seed growth decreased as the soil dried due to a reduction in current photosynthesis as a result of stomatal closure.