Determination of uric acid in canine serum and urine by high performance liquid chromatography

A reproducible high performance liquid chromatography (HPLC) method was developed for analysis of uric acid in canine serum and urine. The method consists of precipitating serum proteins with phosphotungstic acid prior to HPLC analysis. Urine is analyzed after dilution with buffer. Chromatography is performed on a reversed-phase C-18 column with UV detection at 292 nm. Sensitivity of the method will allow reproducible measurement of uric acid at concentrations of 0.05 mg/dl in serum and 0.1 mg/dl in urine. The HPLC method has been used to quantify hundreds of canine serum and urine samples. The method is superior to UV absorption or colorimetric methods because its lower limit of detection allows measurement of uric acid at concentrations found in canine serum and urine.     

云南醉鱼草属(Buddleja L.) 观赏植物资源的调查研究

 在对云南分布的醉鱼草属观赏资源系统调查和资料整理的基础上, 研究了该属植物在云南的地理分布规律及25 种(包括变种) 醉鱼草的观赏性状, 包括花、叶、香气等观赏特征及其开花期, 指出开发利用面对的问题和应采取的措施。     

Uneven-aged management options to promote forest resilience for climate change adaptation: effects of group selection and harvesting intensity

Context

Climate change is expected to increase forest vulnerability through disturbances such as windstorms and droughts. Forest managers are therefore investigating strategies to increase forest resistance and resilience, especially by promoting uneven-aged and mixed forests through group selection, and by reducing stand stocking and large trees proportion. However, there is little information on the long-term impacts of these two practices.

Aims

The objectives of this study were (1) to develop an original silviculture algorithm designed for uneven-aged management and (2) to use it to assess the effects of the above-mentioned management methods in long-term simulations.

Methods

We simulated individual and group selection techniques in order to study the effects of group size, harvesting intensity and their interactions on wood production, stand heterogeneity, and regeneration in mountain spruce–fir forests. We used the spatially explicit individual-based forest model Samsara2 to simulate forest dynamics.

Results

Our simulation results confirmed the positive effect of group selection practices on structure diversity and regeneration but not on spruce maintenance. Increasing harvesting intensity enabled forest destocking but decreased structure diversity and led to non-sustained yields for the most intensive scenarios.

Conclusion

As adaptation measure, we thus recommend moderate group selection harvesting creating 500 m² gaps.     

RhizoTubes as a new tool for high throughput imaging of plant root development and architecture: test,comparison with pot grown plants and validation

Background

In order to maintain high yields while saving water and preserving non-renewable resources and thus limiting the use of chemical fertilizer, it is crucial to select plants with more efficient root systems. This could be achieved through an optimization of both root architecture and root uptake ability and/or through the improvement of positive plant interactions with microorganisms in the rhizosphere. The development of devices suitable for high-throughput phenotyping of root structures remains a major bottleneck.

Results

Rhizotrons suitable for plant growth in controlled conditions and non-invasive image acquisition of plant shoot and root systems (RhizoTubes) are described. These RhizoTubes allow growing one to six plants simultaneously, having a maximum height of 1.1 m, up to 8 weeks, depending on plant species. Both shoot and root compartment can be imaged automatically and non-destructively throughout the experiment thanks to an imaging cabin (RhizoCab). RhizoCab contains robots and imaging equipment for obtaining high-resolution pictures of plant roots. Using this versatile experimental setup, we illustrate how some morphometric root traits can be determined for various species including model (Medicago truncatula), crops (Pisum sativum, Brassica napus, Vitis vinifera, Triticum aestivum) and weed (Vulpia myuros) species grown under non-limiting conditions or submitted to various abiotic and biotic constraints. The measurement of the root phenotypic traits using this system was compared to that obtained using “classic” growth conditions in pots.

Conclusions

This integrated system, to include 1200 Rhizotubes, will allow high-throughput phenotyping of plant shoots and roots under various abiotic and biotic environmental conditions. Our system allows an easy visualization or extraction of roots and measurement of root traits for high-throughput or kinetic analyses. The utility of this system for studying root system architecture will greatly facilitate the identification of genetic and environmental determinants of key root traits involved in crop responses to stresses, including interactions with soil microorganisms.

     

Density, structure, and diversity of the cultivable arylsulfatase-producing bacterial community in the rhizosphere of field-grown rape and barley

In this study we investigated the arylsulfatase-producing bacterial community (ARS-BC) in the rhizosphere soils of field-grown rape in comparison with that of barley. For this, the rhizosphere soils from both plant species were sampled four times during plant growth. Soil arylsulfatase (ARS) activity and the density and the structure of the cultivable ARS-BC on M9-Xsulf medium were then determined. ARS activity in rape rhizosphere was greater than in barley rhizosphere and evolved along the phenology in the two rhizosphere soils. In parallel, the average density of ARS-BC in the rape rhizosphere was higher than that in the barley rhizosphere. Moreover, ARS activity is correlated with ARS-BC density both in rape and barley rhizosphere soils. The structure of the ARS-BC in the rape rhizosphere was different from that in the barley rhizosphere. In the rape rhizosphere, the ARS-BC was substantially more structured than in the barley rhizosphere. Among the ARS-BC, Actinobacteria and Pseudomonads were significantly present in the both rhizosphere soils. Actinobacteria predominated in the barley rhizosphere while Pseudomonads were mostly represented under rape. It is possible that the differences in ARS activity observed between rape and barley can be attributed to a different ARS-BC size and/or a different ARS-BC structure under these two plant covers. This impact of rape may be connected to a selective effect of rhizodeposits released by rape roots to the functional bacterial community. Our findings suggest that plant species, via their rhizodeposits, may affect the functional bacterial community and thus influence the dynamic of S in soil.     

Multiscale spatial variability of CO2 emissions and correlations with physico-chemical soil properties

Spatial variability of greenhouse gas (GHG) emissions from agricultural lands is not well known although it has a great impact on the accuracy of GHG budget.The objectives of this study were to assess the spatial variability of CO₂ emission fluxes (CO_2-flux) and correlate these emissions with soil physico-chemical properties at two spatial scales and at different depths using a new geostatistical approach (coregionalization analysis with a drift, CRAD) that performs multiscale spatial analysis.Two agricultural sites with sandy and loamy soils were instrumented at 108 geo-referred sampling points and at two depths during spring 2007 where soil surface CO_2-flux and soil physico-chemical parameters were measured. The CO_2-flux presented spatial patterns characterized by different scales (i.e., non-spatial, small spatial and large spatial scale components), each describing a different fraction of its variability. About a quarter of CO_2-flux variability at the first site and one fifth at the other site was attributed to the non-spatial component. Strongest correlations were obtained between CO_2-flux and soil temperature, water saturation (S_w), elevation, electrical conductivity, soil bulk density, and the C/N ratio, but with differences between sites. Correlations were much stronger at large scale. Analyzing correlations between CO_2-flux and soil properties without discriminating for scales can miss important scale-dependent processes controlling soil gas emissions. Scales at which these processes vary should therefore be taken into account.     

Identification and characterization of complex bioactive oligosaccharides in white and red wine by a combination of mass spectrometry and gas chromatography

Over forty-five complex free oligosaccharides (of which several are novel) have been isolated and chemically characterized by gas chromatography and high resolution and high mass accuracy matrix-assisted laser desorption/ionization mass spectrometry (MALDI-FTICR MS) in red and white wines, Grignolino and Chardonnay, respectively. Oligosaccharides with a degree of polymerization between 3 and 14 were separated from simple monosaccharides and disaccharides by solid-phase extraction. The concentrations of free oligosaccharides were over 100 mg/L in both red and white wines. The free oligosaccharides-characterized for the first time in the present study-include hexose-oligosaccharides, xyloglucans, and arabinogalactans and may be the natural byproduct of the degradation of cell wall polysaccharides. The coupled gas chromatography and accurate mass spectrometry approach revealed an effective method to characterize and quantify complex functional oligosaccharides in both red and white wine.