米糠中的功能养分及其研究现状

米糠是糙米加工的副产物,除自身的营养特性外,因其含有的多种生理活性成分而显示出良好的应用前景。围绕米糠常规养分及生理活性功能成分的类别、理化特性、应用价值和存在问题做一综述,以期为提高米糠应用提供一些参考。

湿地养分截留功能的空间模拟II.模型的完善和应用

对以实验数据为基础建立的初步空间模型进行了验证 ,并用 Maunder和 Mauring的线性回归模型对苇田子模型进行了修正。模拟结果显示 ,辽河三角洲 8万 hm2 苇田每年灌期大约可以去除 32 0 0～ 4 0 0 0 t总氮和 80 t的活性磷 ,但这仅相当于其潜力的 1 /1 0。因此 ,运用河口湿地作为富含营养物质河水入海前的最后过滤屏障 ,对于防止近海水体的富营养化具有重要意义。

湿地养分截留功能的空间模拟Ⅰ.模型的概念和方法

运用河口湿地来削减氮磷入海通量 ,防止近海水体富营养化。首先对辽河三角洲湿地净化系统进行了理论分析 ,并建立了相应的概念模型 ,然后依靠野外实验数据 ,为湿地的营养物去除功能建立了一个空间模型。该模型包括两大部分 :一是灌渠子系统 ,二是苇田子系统。前者使用的是一个非线性回归模型 ,后者则是以百分率为基础的简单模型。该模型在个别灌区试运行后 。

果园生态系统养分循环功能及其经济价值评估

以西安市果园生态系统作为研究对象,通过土壤库养分持留法对西安市果园生态系统全氮、碱解氮、有效磷、速效钾和有机质等常量营养物质的循环功能进行评估,运用影子价格法将各类营养物质的持留量进行价值估算。结果表明西安市果园生态系统平均每年土壤库养分持留总量为5087.39万t,其中每年有机质4733.31万t、全氮281.21万t、碱解氮21.33万t、有效磷6.15万t和速效钾45.38万t。果园生态系统土壤库中有机质的持留量最高,氮的持留量居第二位,钾排第三位,磷的持留量最少。西安市果园生态系统维持养分循环功能的总经济价值平均每年为4410.45×10^4万元,其中每年有机质、碱解氮、有效磷和速效钾的经济价值分别为485.64×10^4万元、256.29×10^4万元、66.79×10^4万元和222.47×10^4万元。可见,西安果园生态系统循环功能中,维持有机质循环功能的经济价值位居第一。

Structure and functional heterogeneity of soil microbial communities in different farmland types on the Loess Plateau

Background,aim,and scope Soil microbes are important drivers of nutrient transformation and energy f low.Reclaiming forest land for agricultural use may have profound effects on soil properties and microbial communities.However,the response of soil microbial communities to soil reclamation in the dryland agroecosystem is less understood.Therefore,it is necessary to investigate the changes of soil microbial communities driven by land use conversion to promote nutrient cycling in reclaimed farmland.Materials and methods Based on the metagenomic technique,we evaluated the microbial composition and function of the newly created farmland(NF)after reclamation with two types of traditional farmland(slope farmland(SF),checkdam farmland(CF))on the Loess Plateau,and explored the response of nutrient cycling function to dominant genera and soil properties.Results The results showed that Proteobacteria,Actinobacteria,and Acidobacteria were prevalent in the three types of farmlands.Compared with SF and CF,NF increased the relative abundance of Actinobacteria and Nocardioides,as well as genes related to amino acid metabolism and carbohydrate metabolism.The relative abundance of functional genes related to carbon and nitrogen cycling in the NF was higher than that in the traditional farmland(SF and CF).The relative abundance of nutrient cycling functional genes was positively correlated with dominant genera in the three types of farmlands.Except for pH,soil physicochemical factors were negatively correlated with genes related to amino acid metabolism and carbon cycle.Discussion Previous studies have shown that the nutrient conditions of the soil may intensify the competition between the eutrophic and oligotrophic microbial populations.After long-term cultivation and fertilization,the soil properties of traditional farmland were significantly different from those of NF,leading to the differentiation of dominant microbial groups.Microbes usually have functional redundancy to cope with changing environments.Soil microbes in traditional farmland may contain more genes related to replication and repair,cell growth and death,and environmental adaptation in response to disturbances caused by agricultural practices.On the contrary,the NF was less disturbed by agricultural activities,and the soil properties were more similar to forest land,so the carbon and nitrogen cycle function genes were more abundant.The nutrient cycling function was affected by the abundance of microbial dominant groups and soil properties,which may be related to the availability of soil nutrients and agricultural disturbance in different farmlands.Aspects of soil microbial-driven nutrient cycling in agriculture could be regulated in sustainable method.Conclusions The change from forest land to farmland kept more carbon and nitrogen cycling function in the newly created farmland,while long-term agricultural activities have drastically changed the functional structure of traditional farmland,resulting in the nutrient cycling function more concentrated to meet the needs of crop growth.Recommendations and perspectives Hence,it is necessary to apply sustainable agricultural method to regulate microbial-driven nutrient cycling.The insights are meaningful for sustainable agricultural development and land management in arid areas.

Intraclonal Resource Sharing and Functional Specialization of Ramets in Response to Resource Heterogeneity in Three Stoloniferous Herbs

Environments with reciprocal patchiness of resources, in which the availability of two resources such as light and soil nutrients are patchily distributed in horizontal space and negatively correlated in each patch, are common in many ecosystems. The strategies by which clonal plants adapt to this type of heterogeneous environment were examined in three stoloniferous herbs,Potentilla reptans L. var. sericophylla Franch., P. anserina L. and Halerpestes ruthenica (Jacq.) Qvcz., commonly inhabiting forest understories, grasslands and low saline meadows, respectively. As pairs of connected ramets were subjected to reciprocal patchiness of light and nutrients, stolon connection between the two ramets significantly enhanced biomass of both ramet growing in low light intensity but high soil nutrient condition (LH ramet) and ramet growing in high light intensity but low soil nutrient condition (HL ramet) as well as whole ramet pairs (consisting of LH ramets and HL ramets). Additionally, stolon connection greatly increased root/shoot ratio of LH ramet while significantly decreased that of HL ramet. The results indicate that a reciprocal transportation of resources between interconnected ramets and a functional specialization of ramets in uptake of abundant resources occurred. By resource sharing and functional specialization, clonal plants can efficiently acquire locally abundant resources and buffer the stress caused by reciprocal patchiness of resources.

Effects of glycine on phagocytosis and secretion by Kupffer cells in vitro

AIM:To investigate the effects and mechanisms of action of glycine on phagocytosis and tumor necrosis factor(TNF)-α secretion by Kupffer cells in vitro. METHODS:Kupffer cells were isolated from normal rats by collagenase digestion and Percoll density gradient differential centrifugation.After culture for 24 h,Kupffer cells were incubated in fresh Dulbecco's Modification of Eagle's Medium containing glycine (G1:1 mmol/L,G2:10 mmol/L,G3:100 mmol/L and G4:300 mmol/L)for 3 h,then used to measure phagocytosis by a bead test,TNF-α secretion after lipopolysaccharide stimulation by radioactive immunoassay,and microfilament and microtubule expression by staining with phalloidin-fluorescein isothiocyanate (FITC)or a monoclonal anti-α tubulin-FITC antibody, respectively,and evaluated under a ultraviolet fluorescence microscope. RESULTS:Glycine decreased the phagocytosis of Kupffer cells at both 30 min and 60 min(P<0.01,P< 0.05).The numbers of beads phagocytosed by Kupffer cells in 30 min were 16.9±4.0(control),9.6±4.1(G1), 12.1±5.7(G2),8.1±3.2(G3)and 7.5±2.0(G4),and were 22.5±7.9(control),20.1±5.8(G1),19.3±4.8 (G2),13.5±4.7(G3)and 9.2±3.1(G4)after 60 min. TNF-α secretion by Kupffer cells in G1(0.19±0.03),G2 (0.16±0.04),G3(0.14±0.03)and G4(0.13±0.05) was significantly less than that in controls(0.26±0.03, P<0.01),and the decrease in secretion was dose-dependent(P<0.05).Microfilaments of Kupffer cells in G2, G3 and G4 groups were arranged in a disorderly manner. The fluorescence densities of microtubules in G1(53.4± 10.5),G2(54.1±14.6),G3(64.9±12.1)and G4(52.1 ±14.2)were all lower than those in the controls(102.2 ±23.7,P<0.01),but the decrease in microtubule fluorescence density was not dose-dependant. CONCLUSION:Glycine can decrease the phagocytosis and secretion by Kupffer cells in vitro,which may be related to the changes in the expression of microfilaments and microtubules induced by Kupffer cells.

Biomass and bio-energy production of ten multipurpose tree species planted in sodic soils of indo-gangetic plains

Ten multipurpose tree species, Terminalia arjuna, Azadirechta indica, Prosopis juliflora, Pongamia pinnata, Casuarina equisetifolia, Prosopis alba, Acacia nilotica, Eucalyptus tereticornis, Pithecellobium dulce and Cassia siamea, were raised in a monoculture tree cropping system on the sodic soil of Gangetic alluvium in north India （26° 47° N： 80°46′ E） for 10 years to evaluate the biomass and bio-energy production. The soil was compact, sodic and impervious to water associated with nutrient deficiency or toxicity. Maximum plant height was recorded with E. tereticornis followed by C.equisetifolia and P. juliflora. A. nilotica performed better than the other species in terms of diameter at breast height （DBH） with a basal area of 13.04 m^2·ha^-1, followed by P. juliflora and C. equisetifolia. P. juliflora and A. nilotica produced nearly similar biomass of 56.50 and 50.75 Mg·ha^-1, respectively, at 10 years; whereas, A. indica, P. pinnata, C. siamea and P. alba did not perform well. P. juliflora scored maximum in net biomass production and nutrient demand. Nutrient （N, P, K, Ca, and Mg） concentrations were higher in leaf component of P. juliflora. However, in woody components, there was little variation between the species. N removal for production of one ton of wood was lowest in Acacia nilotica, P in T. arjuna, K in P. dulce and Ca and Mg in P. juliflora. P. juliflora gave the highest energy production of 1267.75 GJ.ha^-1 followed by A. nilotica with 1206 GJ.ha^-1 and the lowest ofA. indica （520.66 GJ.ha^-1）.

Influence of dietary n-3 LC-PUFA on growth, nutritional composition and immune function in marine fish Sebastiscus marmoratus

Abstract A 60-day feeding experiment was conducted to investigate the influence of dietary omega-3 long-chain polyunsaturated fatty acids （n-3 LC-PUFA） on growth, nutritional composition and immune function of marine fish Sebastiscus marmoratus. Five diets containing 3.6, 10.2, 18.2, 26.5, or 37.0 g/kg n-3 LC-PUFA were prepared. The results reveal significant influences of dietary n-3 LC-PUFA on the final weight, weight gain, specific growth rate, feed conversion ratio, and condition factor. As dietary n-3 LC- PUFA increased, weight gain and specific growth rate increased and were significantly higher in groups fed 18.2, 26.5 and 37.0 g/kgthan in groups fed 3.6 and 10.2 g/kg （P〈0.05）; there was no significant difference between groups fed 18.2, 26.5, or 37.0 g/kg （P〉0.05）. With increasing dietary n-3 LC-PUFA, eicosapentaenoic acid and docosahexenoic acid content in muscle and liver increased significantly, immunoglobulin class M content gradually increased from 9.1 to 14.8 Ixg/L, and lysozyme activity content increased from 1 355 to 2 268 U/mL. Broken line model analysis according to weight gain indicated that a dietary n-3 LC-PUFA level of 18.2 g/kg is essential for normal growth at a fat level of 125 g/kg. Therefore, appropriate dietary n-3 LC-PUFA not only promote growth and improve the n-3 LC-PUFA content, but also enhance immune function in S. marmoratus.

Contrasting responses of native and alien plant species to soil properties shed new light on the invasion of dune systems

Aims Among terrestrial ecosystems,coastal sandy dunes are particularly prone to alien plant invasion.Many studies related the invasion of dune habitats to anthropic causes,but less is known about the role of soil properties and plant traits in plant invasion.In this study,we tested the relationships between soil features and alien plant invasion in dune systems,focusing on the interplay between soil nutrients,soil salinity and plant functional traits.Methods Study sites were sandy barrier islands of the Marano and Grado lagoon(northern Adriatic Sea).One hundred plots(4 m×4 m)were selected within 10 areas according to the main habitats occurring along the ecological gradient of dune system(foredune,backdune and saltmarsh).In each plot,we recorded all plant species occurrence and abundance and we collected a soil core.For each soil sample,soil texture,conductivity(as proxy of soil salinity),organic carbon and nitrogen content were analyzed and related to the species number and cover of native and alien plants.Variation of main reproductive and vegetative functional traits among habitats was also analyzed for both alien and native species.Important Findings Soil properties were strongly related to overall plant diversity,by differently affecting alien and native species pools.In backdune,the most invaded habitat,a high soil conductivity limited the number of alien species,whereas the content of soil organic carbon increased along with alien plant abundance,suggesting also the occurrence of potential feedback processes between plant invasion and soil.We found a significant convergence between native and alien plant functional trait spectra only in backdune habitat,where environmental conditions ameliorate and plant competition increases.Our findings suggest that in harsh conditions only native specialized plants can thrive while at intermediate conditions,soil properties gradient acts in synergy with plant traits to curb/facilitate alien plant richness.

Functional traits influence plant survival depending on environmental contexts and life stages in an old-growth temperate forest

Aims Functional traits are usually used to predict plant demographic rates without considering environmental contexts.However,previous studies have consistently found that traits have low explanatory power for plant demographic rates.We hypothesized that accounting for environmental contexts instead of focusing on traits alone could improve our understanding of how traits influence plant demographic rates.Methods We used generalized linear mixed-effect models to analyse the effects of functional traits(related to leaf,stem,seed and whole plant),environmental gradients(soil nutrients,water and elevation)and their interactions on the survival dynamics of 14133 saplings and 3289 adults in a 9-ha old-growth temperate forest plot.Important Findings We found that environmental variables,neighbour crowding and traits alone(i.e.main effects)influenced plant survival.However,the effects of the latter two variables varied between saplings and adults.The trait–environment interactions influenced plant survival,such that resource conservative traits increased plant survival under harsh conditions but decreased survival under mild conditions.The elevational gradient was the most important environmental factor driving these effects in our plot.Our results support the hypothesis that functional traits influence plant survival depending on environmental contexts in local communities.These results also imply that one species with limited trait variation cannot occupy all environments,which can promote species diversity.

Comparisons of photosynthesis-related traits among understory lichens,mosses and vascular plant leaves in a high-elevation subalpine forest

Many mosses and lichens thrive in high-elevation subalpine forests and even become dominant species on the forest foor.Although they play an irreplaceable ecological role in the forest,less is known about their ecophysiological status,and how their photosynthesis-related functional traits differ from those of co-occurring vascular plants.We determined the carbon,nitrogen and phosphorus concentrations and stoichiometric ratios,tissue mass per area,chlorophyll concentrations and photosynthetic light–response curves of three lichens,three mosses and four vascular plants in a subalpine forest in the eastern Tibetan Plateau of China.Trait values were compared among and within each group.The lichens possessed a higher nitrogen concentration than that of mosses.In addition,the two poikilohydric groups exhibited lower concentrations of nitrogen,phosphorus and chlorophyll,light-saturated assimilation rates and photosynthetic nutrient use effciencies,and higher light compensation points than those of vascular plant leaves.Furthermore,variations in photosynthesis-related traits for lichen species refect their different adaptation strategies to their corresponding environments.In contrast,the differences were weak among the three forest-foor mosses and the three herb species.These results demonstrate that the high abundance of understory lichens and mosses in the high-elevation subalpine forest cannot be explained by the photosynthesis-related traits.

Annual mowing mitigates the negative legacy effects of N enrichment on grassland nutrient use efficiency

Aims Plant nutrient use efficiency,an important factor driving primary production,is sensitive to nitrogen(N)deposition.Because of strengthened regulations of N emissions,atmospheric N deposition is decreasing in many countries.It remains unknown whether historical N enrichment would alter plant nutrient use efficiency and whether such impacts would be mitigated by ecosystem management strategy.Methods We assessed the effects of historical N addition and mowing on plant N and phosphorus use efficiency(NUE and PUE)at both functional group and community levels in a temperate steppe after the cessation of 6-year N addition.Important Findings Historical N addition had negative legacy effects on plant NUE but not on PUE at the functional group level.There were negative legacy effects of N addition on community-level NUE and PUE,but only in the unmown plots.Mowing mitigated the negative legacy effects of N enrichment on community-level NUE and PUE by reducing the dominance of tall rhizomatous grass but enhancing that of tall bunchgrass.Our results highlight the importance of community composition variations caused by mowing in driving the legacy effects of N enrichment on community-level nutrient use efficiency.Given the slow recovery of community composition following cessation of N deposition,our findings suggest that the lower nutrient efficiency of plant community would be long-lasting.