Stable isotope N and C labelling of different functional groups of earthworms and their casts: A tool for studying trophic links

Earthworms (Oligochaeta: Lumbricidae) have substantial effects on the structure and fertility of soils with consequences for the diversity of plant communities and associated ecosystem functions. However, we still lack a clear understanding of the functional role earthworms play in terrestrial ecosystems, partly because easy-to-use methods to quantify their activities are missing. In this study, we tested whether earthworms and their casts can be dual-labelled with ¹⁵N and ¹³C stable isotopes by cultivating them in soil substrate amended with ¹⁵N ammonium nitrate and ¹³C-glucose. Additionally, we also wanted to know whether (i) earthworms from different functional groups (soil-feeders vs. litter-feeders) and their casts would differ in their incorporation of stable isotopes, (ii) if enrichment levels are higher if the same amount of isotopes is applied in one dose or in staggered doses, and (iii) if isotopic enrichment in casts changes when they are stored in a conditioning cabinet or in a pot filled with soil placed in a greenhouse. Our findings show the feasibility of dual-labelling tissues and casts of both litter-feeding (Lumbricus terrestris) and soil-feeding (Aporrectodea caliginosa) earthworms using the same method. The advantage of this method is that earthworms and their casts can be labelled under realistic conditions by cultivating them for only four days in soil that received a one-time addition of commercially available stable isotopes instead of offering labelled plant material. In earthworms, the isotopic enrichment remained at a stable level for at least 21 days; labelled casts could be stored for at least 105 days without significantly decreasing their isotopic signals. This simple and efficient method opens new avenues for studying the role of these important ecosystem engineers in nutrient cycling and their functional relationships with other organisms.     

~(86)R_b与K的作物吸收及其在土壤中移动的相关性

实验结果表明:西红柿、红麻、高梁和玉米作物之间对R_b与K吸收的相关系数为r=0.9842,各生育期对R_b与K吸收及分布的相关系数均在0.9以上,因此可以用R_b做K的示踪剂研究这些作物对钾的吸收。R_b与K在土壤中移动、分布的相关性受质地、水分状况影响较大,用R_b做示踪剂研究K在土壤中的移动要慎重。     

美国与欧盟的转基因食品安全性政策演变比对(英文)

随着转基因食品的研究与发展,人们对待转基因食品的态度表现为主要以美国和欧盟为主的两种代表性政策美国采取遵循可靠科学原则,坚决反对预防原则,即对转基因食品采取积极支持,自愿标识的宽松政策;欧盟采取谨慎预防原则,必须标识和可追溯从管理原则出发,结合相应采取的监管措施和相关条例,对两国从开始颁布转基因食品政策到当下态势的发展,并结合最新出台的政策进行跟踪分析,比对美国及欧盟对这些指令和条例的执行情况。     

A yield mapping system for hand-harvested fruits based on RFID and GPS location technologies: field testing

It is proposed that radio frequency identification (RFID) technology be used to overcome the limitations of existing yield mapping systems for manual fresh fruit harvesting. Two methods are proposed for matching bins—containing harvested fruits—with corresponding pairs of trees. In the first method, a long-range RFID reader and a DGPS are mounted on an orchard tractor and passive low-cost RFID tags are attached to the bins. In the second method, the DGPS is not used and RFID tags are attached to individual trees as well as bins. An experimental evaluation of the accuracy and reliability of both methods was performed in an orchard. The first method failed in half of the trials because the tree canopies interfered with the GPS signal. The RFID reader miss ratio for the detection of the bins was 0.32% for both methods. However, the attachment of RFID tags on suitable tree branches (to achieve 100% detection), in the second method, is not a well-defined procedure; some trial is demanded to determine the best positions and orientations of the tree tags in order for the RFID reader to successfully detect them. The first method seems more promising if robust tractor location under foliage can be achieved.     

芦笋 香菇 苋菜 芥蓝菜汁对肿瘤生长的抑制作用

本实验采用~3H-TdR参入法,观察了芦笋、香菇,苋莱、芥蓝4种蔬菜(共8个品种)对小鼠艾氏腹水癌实体瘤生长的抑制作用。结果表明,这4种蔬菜对肿瘤生长均有不同程度的抑制作用,其中以芦笋、香菇的效果较好。值得注意的是同种蔬菜不同品种的抑癌效果有所不同。     

猪圆环病毒2型抗体免疫金标检测试纸的研制

应用酶联免疫原理和胶体金层析技术,采用特殊的生产工艺,在玻璃纤维膜包被胶体金标记PCV-2抗原,在硝酸纤维素膜上检测线和对照线处分别包被PCV-2抗原和兔抗PCV-2抗体,制成猪圆环病毒2型抗体免疫金标检测试纸.当待检样品阳性时,在检测线处形成抗原抗体的免疫复合物而凝聚显色;当待检样品阴性时,检测线处不形成抗原抗体免疫复合物不显色.整个试验过程只需15 min.试纸与ELISA试剂比较,两者都具有微量、特异、准确的优点,且金标试纸独具操作方便、快速和结果直观、容易判定的优点.     

A simple and rapid method for labelling earthworms with N and C

A simple, rapid and cost-effective laboratory method was developed for labelling soil-feeding earthworms simultaneously with ¹⁵N and ¹³C. The method circumvents the production of labelled plant material and can be adapted to devise pulse-labelling or long-term labelling protocols. Soil was amended with ¹⁵NH₄⁺ and incubated for 7 days. Then, U-¹³C-glucose was added and endogeic earthworms, Aporrectodea caliginosa (Oligochaeta: Lumbricidae), were provided individually with 4 g of this pre-incubated soil. The labelling period was 4 days. The labelling efficiency (percentage of tracer retained in earthworm tissues) was estimated to be 15.8% for ¹⁵N and 10.3% for ¹³C. The loss of ¹⁵N and ¹³C label from tissue and mucus was traced for 21 days post-labelling. Label loss from mucus was best described by a two-term exponential function, whereas the label loss in body tissue followed a single-term exponential function. Half-life estimates for the ¹⁵N and ¹³C tracers in body tissue were 16 and 37 days, respectively.     

PCR制备地高辛标记的探针检测禽流感病毒核酸

用聚合酶链反应（PCR）技术,制备了广东禽流感无致病力分离株A/goose/China/24/96(H7N3）核蛋白基因片段（NPc）的地高辛标记的cDNA探针。建立并优化了检测禽流感病毒核酸的探针杂交法,探针杂交法能鉴别出非免疫鸡胚和SPF鸡胚尿囊液中的病毒,攻毒后第3天的SPF和非免疫鸡泄殖腔拭子中AIV的最大检出率为1/10,对临床样品中的AIV的最大检出率为1/7,而直接HA和HI法及AGP试验检不出临床样品的AIV。该探针具有较好的特异性和敏感性,为从分子水平探讨AIV的发病机理、临床早期快速诊断提供了新的研究手段。     

原条量材设计有向图的标号解法及其应用

用标号法求解原条量材设计有向图T=(X,Y,ω_(ij))的原条售价最高路时,用邻接矩阵找出各点的可能路后,再根据某点最大值等于前一点最大值与两点间权值之和的原理,在所有可能路中找到最大值。根据这一原理,本文提出,量材员在原务量材设计生产活动中,必须从下述3点入手,方能既准又快地找出最佳方案来。①要以8m为定案点,从8条路中找最大值;②所有可能路中,出现同等级路,按材长取路,邻等级路,高等级占2/3时,按等级取路,否则按材长取路,隔等级路,按等级取路;③检尺直径在24～18cm、检尺长度不足4m者,一般按坑木取路,检尺直径16cm以下者,按檩条取路。