肾俞穴,后三里穴与子宫相关的神经基础

应用辣根过氧化物酶（ＨＲＰ）法和荧光素双标记法，研究了家兔子宫与肾俞穴、后三里穴的外周神经联系。结果显示，支配子宫与肾俞穴、后三里穴的初级传入神经元及交感节后神经元分布节段部分重叠，在腰１（Ｌ１）脊神经节有少量的荧光素双标记细胞，约占该节荧光素标记细胞总数的２．６％，表明Ｌ１脊神经节有一些初级传入神经元，其周围突分支分布于肾俞穴和子宫，提示子宫与肾俞穴除通过中枢途径联系外，还可通过外周突分支投射的感觉神经元直接相联系；在胸１２～荐３（Ｔ１２～Ｓ３）交感神经节出现大量分别支配子宫和后三里穴的标记细胞，这两种细胞紧密相邻，提示支配子宫和后三里穴的交感节后神经元之间，可能还存在直接或间接联系。上述结果为穴位－内脏相关机理提供了形态学证据。     

Effect of take-all root infections on nitrate uptake in winter wheat

The effect of take-all root lesions on nitrate uptake of wheat was investigated in two experiments under controlled conditions. Plants were supplied with a nutrient solution labelled with ¹⁵N during stem elongation and flowering to assess the distribution of the isotopic tracer in the different plant organs, and particularly in root segments located on both sides of take-all lesions. The ¹⁵N atom percentage excess measured in root segments located below lesions longer than 1 cm was reduced on average by half compared with that in healthy roots and root segments above lesions, reflecting a reduction in nitrogen uptake by these root segments. This reduction probably resulted from the invasion and breakdown of phloem vessels by the fungus hyphae, interrupting energy supply and thus the uptake process. Severely infected plants showed an increase in the uptake rate per unit of efficient root, which appeared to be a compensatory response to reduction of efficient root biomass in order to satisfy shoot nitrogen demand. However, this compensatory response was insufficient to ensure nitrogen accumulation equivalent to that of healthy plants, as reductions in nitrogen accumulated in roots and aerial parts at flowering were up to 56 and 49%, respectively, for plants with more than 50% of the root system below lesions longer than 1 cm.     

Non-structural plum pox potyvirus proteins detected by immunogold labelling

Plum pox potyvirus (PPV) induces in infected Nicotiana clevelandii cells characteristic crystalline inclusions known as nuclear inclusions (NI) when located in the nucleus and as dense material (Dm) when located in the cytoplasm. Crystalline inclusions contain protease (NIa) and RNA-dependent RNA polymerase (NIb) proteins. It is now well established for all potyviruses that cylindrical inclusions contain CI helicase ATPase protein (Martin et al., 1992). The intracellular location of other non-structural PPV proteins remains unknown. Using Escherichia coli expression vectors, specific antibodies were obtained against P1, P3, 6K2 and NIb PPV proteins for which antibodies were not yet available. As expected, NIb antiserum labelled crystalline inclusions. P1, P3 and 6K2 proteins were present in both types of crystalline inclusions found in the nucleus and in the cytoplasm of PPV-infected leaves of N. clevelandii, suggesting that nuclear inclusions and dense material were composed of the same proteins. This composition is discussed.     

Long-term fertilization effects on active ammonia oxidizers in an acidic upland soil in China

The effects of long-term fertilization of acidic soils on ammonia-oxidizing archaea (AOA) and bacteria (AOB) communities and its ecological implications remain poorly understood. We chose an acidic upland soil site under long-term (27-year) fertilization to investigate ammonia oxidizer communities under four different regimes: mineral N fertilizer (N), mineral NPK fertilizer (NPK), organic manure (OM) and an unfertilized control (CK). Soil net nitrification rates were significantly higher in OM soils than in CK, N or NPK soils. Quantitative analysis of the distribution of amoA genes by DNA-based stable isotope probing revealed that AOA dominate in CK, N and NPK soils, while AOB dominate in OM soils. Denaturing gradient gel electrophoresis and clone library analyses of amoA genes revealed that Group 1.1a-associated AOA (also referred to as Nitrosotalea) were the most dominant active AOA population (>92%), while Nitrosospira Cluster 3 and Cluster 9 were predominant among active AOB communities. The functional diversity of active ammonia oxidizers in acidic soils is affected by long-term fertilization practices, and the responses of active ammonia oxidizers to mineral fertilizer and organic manure are clearly different. Our results provide strong evidence that AOA are more highly adapted to growth at low pH and low substrate availability than AOB, and they suggest that the niche differentiation and metabolic diversity of ammonia oxidizers in acidic soils are more complex than previously thought.     

不同耕作模式下水稻产量与器官多要素响应的比较研究

认识和理解水稻产量影响要素是实现水稻高产稳产的关键。选取冬水田、垄作免耕和常规水旱轮作3种处理,采用相关分析、主成分分析与主成分多元线性回归3种方法对水稻产量与成熟期根、茎、叶、籽粒碳同位素组成,根系特征以及养分的响应关系进行比较与综合分析。结果表明不同耕作模式下垄作免耕的水稻产量最高,根、茎、叶、籽粒的碳同位素组成与水稻产量有极显著的负相关关系(P0.01);主成分分析提取的6个主成分累计贡献率超过80%;主成分多元线性回归模型能够解释冬水田、垄作免耕和常规水旱轮作水稻产量67%、73%和97%的变异;与常规水旱轮作相比,冬水田和垄作免耕水稻产量与碳同位素组成及磷的关系更密切。该研究表明,垄作免耕具有较好的推广应用价值。     

Oxygen isotope ratios of plant available phosphate in lowland tropical forest soils

Phosphorus (P) cycles rapidly in lowland tropical forest soils, but the process have been proven difficult to quantify. Recently it was demonstrated that valuable data on soil P transformations can be derived from the natural abundance of stable oxygen isotopes in phosphate (δ¹⁸O_P). Here, we measured the δ¹⁸O_P of soils that had received long-term nutrient additions (P, nitrogen, and potassium) or litter manipulations in lowland tropical forest in Panama and performed controlled incubations of fresh soils amended with a single pulse of P. To detect whether δ¹⁸O_P values measured in the incubations apply also for soils in the field, we examined the δ¹⁸O_P values after rewetting dry soils. In the incubations, resin-P δ¹⁸O_P values converged to ∼3.5‰ above the expected isotopic equilibrium with soil water. This contrasts with extra-tropical soils in which the δ¹⁸O_P of resin-P matches the expected equilibrium with soil water. Identical above-equilibrium resin-P δ¹⁸O_P values were also found in field soils that did not receive P additions or extra litter. We suggest that the 3.5‰ above-equilibrium δ¹⁸O_P values reflect a steady state between microbial uptake of phosphate (which enriches the remaining phosphate with the heavier isotopologues) and the release of isotopically equilibrated cell internal phosphate back to the soil. We also found that soil nutrient status affected the microbial turnover rate because in soils that had received chronic P addition, the original δ¹⁸O_P signature of the fertilizer was preserved for at least eight weeks, indicating that the off-equilibrium δ¹⁸O_P values produced during microbial phosphate turnover was not imprinted in these soils. Overall, our results demonstrate that ongoing microbial turnover of phosphate mediates its biological availability in lowland tropical soils.     

Contribution of Different Organs to Grain Filling in Durum Wheat under Mediterranean Conditions I. Contribution of Post‐Anthesis Photosynthesis and Remobilization

Under Mediterranean conditions, drought affects cereals production principally through a limitation of grain filling. In this study, the respective role of post‐anthesis photosynthesis and carbon remobilization and the contribution of flag leaf, stem, chaff and awns to grain filling were evaluated under Mediterranean conditions in durum wheat (Triticum turgidum var. durum) cultivars. For the purpose, we examined the effects of shading and excision of different parts of the plant and compared carbon isotope discrimination (Δ) in dry matter of flag leaf, stem, chaff, awns and grain at maturity and in sap of stem, flag leaf, chaff and awns, this last measurement providing information on photosynthesis during a short period preceding sampling. Source–sink manipulations and isotopic imprints of different organs on final isotope composition of the grain confirmed the high contribution of both carbons assimilated by ears and remobilized from stems to grain filling, and the relatively low contribution of leaves to grain filling. Grain Δ was highly and significantly associated with grain yield across treatments, suggesting the utilization of this trait as an indicator of source–sink manipulations effects on grain yield. Chaff and awns Δ were better correlated with grain Δ than stem and leaf Δ, indicating that chaff were more involved in grain filling than other organs. Moreover, in chaff, sap Δ was highly significantly correlated with dry matter Δ. These results suggest the use of Δ for a rapid and non‐destructive estimation of the variation in the contribution of different organs to grain filling.     

稳定碳、氮同位素在牛肉加工过程中的分馏效应

为了探究牛肉及副产物中稳定碳、氮同位素在加工过程中的变化规律,确证稳定碳、氮同位素在牛肉加工制品产地溯源中的稳定性和有效性。本试验通过对牛肉进行不同时间的水煮、烤制和油炸3种处理,其中水煮和烤制加工时间分别为5、10、15、20、25和30 min,油炸加工时间分别为1、2、3、4和5 min;采用元素分析仪-稳定同位素比率质谱仪(EA-IRMS)测定脱脂牛肉、粗脂肪及副产物中δ¹³C和δ¹⁵N值。结果表明,脱脂牛肉中δ¹³C值在水煮、烤制和油炸3种加工方式不同加工时间之间均无显著差异,水煮和烤制后粗脂肪中δ¹³C值无显著变化,油炸后的牛肉粗脂肪δ¹³C值主要受植物油的影响,加工方式及加工时间对其无显著影响;水煮脱脂牛肉δ¹⁵N值在加工25、30 min时与对照组牛肉存在显著差异,但平均差值仅为0.3‰~0.9‰。牛肉稳定碳、氮同位素在不同加工过程中分馏效应较小,可有效用于牛肉加工半成品及成品的原产地溯源。     

明胶骨原料碳、氮稳定同位素的地域性差异研究

为探讨不同地域来源的明胶骨原料中碳、氮稳定同位素的分布特征及其相关性,本试验采用元素分析-稳定同位素比率质谱仪测定了广西、内蒙古和山东3个主产区的牛骨样品及当地牧草饲料样品中的¹³C和¹⁵N同位素组成,并结合线性回归讨论了牛骨样品中δ¹³C和δ¹⁵N值的相关性与牛食谱组成的关系。结果表明,广西地区骨样品中δ¹³C和δ¹⁵N值的相关性较好(R²=0.401 8),而内蒙古和山东地区骨样品中δ¹³C和δ¹⁵N值的相关性较差(R²<0.1),反映了3地牛食物的来源稳定性及主要成分存在明显差异,对各地牛食谱结构推测的结果与实际牧草饲料样品中δ¹³C和δ¹⁵N值的地区分布规律也较为一致。本研究初步揭示了明胶骨原料中碳、氮稳定同位素产生地域性差异的原因,不仅为动物生态学研究提供了有益信息,更为动物制品产地溯源研究提供了新思路。