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51.
Malavia J Abalos M Santos FJ Abad E Rivera J Galceran MT 《Journal of agricultural and food chemistry》2007,55(26):10531-10539
This paper reports on the applicability of gas chromatography coupled to ion-trap tandem mass spectrometry (GC/ITMS/MS) for the analysis of polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in food. MS/MS parameters were selected to achieve the high sensitivity and selectivity required for food analysis. Good precision (RSD=5-18% for PCDD/Fs and 6-14% for dl-PCBs) and low limits of detection for PCDD/Fs (0.1-0.93 pg/g of fat) and dl-PCBs (0.1-0.89 pg/g of fat) were obtained. A comparative study of the congener-specific determination using both GC/ITMS/MS and GC-high resolution mass spectrometry (GC/HRMS) was performed by analyzing several matrices such as milk, fish oil, chicken, pork, fish, eggs, and a chicken compound feed, at low pg/g levels. The results using GC/ITMS/MS were in good agreement with those obtained by GC/HRMS. Consequently, GC/ITMS/MS is proposed for the analysis of PCDD/Fs and dl-PCBs in food and feed samples. 相似文献
52.
Aboveground stand-level biomass estimation: a comparison of two methods for major forest species in northwest Spain 总被引:1,自引:0,他引:1
Fernando Castedo-Dorado Esteban Gómez-García Ulises Diéguez-Aranda Marcos Barrio-Anta Felipe Crecente-Campo 《Annals of Forest Science》2012,69(6):735-746
Context
The scaling-up approach (which requires the use of individual tree biomass equations and data) is one of the most commonly used methods for estimating stand biomass at a local scale. However, biomass prediction over large management areas requires more efficient methods.Aims
Two methods of estimating aboveground stand biomass were developed and compared: stand biomass equations (SBE) including observed stand variables, and SBE including biomass expansion factors (BEF) and stand volume.Methods
Two types of systems of additive equations were fitted simultaneously for components and total aboveground stand biomass, to ensure additivity. Inherent correlations among biomass components were also taken into account in the fitting process.Results
The systems explained a high percentage of the observed variability. The SBE systems that included observed stand variables provided more accurate estimates than those that included BEF and stand volume. However, the latter were found to be more precise for stem wood and total aboveground biomass prediction.Conclusions
Both approaches provide a direct link between forest inventory data, outputs from whole-stand growth models, and biomass estimates at stand level. Taking into account that the inventory effort is similar for both alternatives, the choice of which to use will depend on the data available and on the relative importance of the biomass components for the end-users. 相似文献53.
Luis G. Esteban Juan A. Martín Paloma de Palacios Francisco García Fernández 《European Journal of Forest Research》2012,131(3):633-645
Region of provenance is defined as an area with uniform ecological conditions where stands with similar phenotypic or genetic
features are found. This study assesses the effect of differing climate conditions of eight Spanish regions of provenance
of Pinus nigra Arn. subsp. salzmannii on earlywood anatomical traits measured in samples from basal discs from mature trees. Results showed that variation in wood
biometry between provenances was high and more pronounced than intrapopulation variation. When comparing P. nigra with other Mediterranean pines, high intertracheid wall strength values are associated with better adaptation of pines to
arid conditions. However, the intraspecific variations of this parameter in P. nigra did not follow the same pattern, due to the influence of mechanical support requirements. Trees subject to greater aridity
were characterised by short tracheids, apparently resulting from their poorer growth, and high frequency of rays and ray parenchyma
cells, which would allow trees to store greater amounts of starch, which is the source of metabolites invested in minimising
the limitations imposed by water stress. Severe winter cold spells were strongly associated with high axial resin canal frequency
and large radial resin canals, creating a powerful, preformed defence system. Increased tracheid lumen involved an increase
in the size of bordered pits, favouring sap flow between tracheids, in addition to an increase in the maximum diameter of
cross-field pits, favouring the flow of water and metabolites between the axial and radial systems. The high influence of
region of provenance on structural variation in P. nigra shows the importance of provenance in the selection of seed origin for reforestation. 相似文献
54.
Kenny EE Timpson NJ Sikora M Yee MC Moreno-Estrada A Eng C Huntsman S Burchard EG Stoneking M Bustamante CD Myles S 《Science (New York, N.Y.)》2012,336(6081):554
Naturally blond hair is rare in humans and found almost exclusively in Europe and Oceania. Here, we identify an arginine-to-cysteine change at a highly conserved residue in tyrosinase-related protein 1 (TYRP1) as a major determinant of blond hair in Solomon Islanders. This missense mutation is predicted to affect catalytic activity of TYRP1 and causes blond hair through a recessive mode of inheritance. The mutation is at a frequency of 26% in the Solomon Islands, is absent outside of Oceania, represents a strong common genetic effect on a complex human phenotype, and highlights the importance of examining genetic associations worldwide. 相似文献
55.
Ivancich HS Lencinas MV Pastur GJ Esteban RM Hernández L Lindstrom I 《Tree physiology》2012,32(5):554-564
Foliar anatomy and morphology are strongly related to physiological performance; therefore, phenotypic plasticity in leaves to variations in environmental conditions, such as irradiance and soil moisture availability, can be related to growth rate and survivorship, mainly during critical growth phases, such as establishment. The aim of this work was to analyze changes in the foliar internal anatomy (tissue proportions and cell dimensions) and external morphology (leaf length, width and area) of Nothofagus pumilio (Poepp. et Endl.) Krasser seedlings growing in a greenhouse under controlled irradiance (three levels) and soil moisture (two levels) during one growing season (measured three times), and to relate them to physiological traits. Three irradiance levels (4, 26 and 64% of the natural incident light) and two soil moisture levels (40 and 80% soil capacity) were evaluated during November, January and March. Internal foliar anatomy of seedlings was analyzed using digital photographs of histological cuttings, while leaf gross morphology was measured using digital calipers and image analysis software. Most internal anatomical variables presented significant differences under different irradiance levels during the growing season, but differences were not detected between soil moisture levels. Palisade parenchyma was the tissue most sensitive to irradiance levels, and high irradiance levels (64% natural incident light) produced greater values in most of the internal anatomical variables than lower irradiance levels (4-24% natural incident light). Complementarily, larger leaves were observed in medium and low irradiance levels, as well as under low soil moisture levels (40% soil capacity). The relationship of main results with some eco-physiological traits was discussed. Foliar internal anatomical and external morphological plasticity allows quick acclimation of seedlings to environmental changes (e.g., during harvesting). These results can be used to propose new forest practices that consider soil moisture and light availability changes to maintain high physiological performance of seedlings. 相似文献
56.
57.
Vila-Aiub MM Balbi MC Distéfano AJ Fernández L Hopp E Yu Q Powles SB 《Pest management science》2012,68(3):430-436
BACKGROUND: In a large cropping area of northern Argentina, Sorghum halepense (Johnsongrass) has evolved towards glyphosate resistance. This study aimed to determine the molecular and biochemical basis conferring glyphosate resistance in this species. Experiments were conducted to assess target EPSPS gene sequences and 14C‐glyphosate leaf absorption and translocation to meristematic tissues. RESULTS: Individuals of all resistant (R) accessions exhibited significantly less glyphosate translocation to root (11% versus 29%) and stem (9% versus 26%) meristems when compared with susceptible (S) plants. A notably higher proportion of the applied glyphosate remained in the treated leaves of R plants (63%) than in the treated leaves of S plants (27%). In addition, individuals of S. halepense accession R2 consistently showed lower glyphosate absorption rates in both adaxial (10–20%) and abaxial (20–25%) leaf surfaces compared with S plants. No glyphosate resistance endowing mutations in the EPSPS gene at Pro‐101–106 residues were found in any of the evaluated R accessions. CONCLUSION: The results of the present investigation indicate that reduced glyphosate translocation to meristems is the primary mechanism endowing glyphosate resistance in S. halepense from cropping fields in Argentina. To a lesser extent, reduced glyphosate leaf uptake has also been shown to be involved in glyphosate‐resistant S. halepense . Copyright © 2011 Society of Chemical Industry 相似文献
58.
59.
Salinas I Myklebust R Esteban MA Olsen RE Meseguer J Ringø E 《Veterinary microbiology》2008,128(1-2):167-177
Probiotic bacteria increase the host health status and protect mucosal tissue against pathogen-caused damage in mammalian models. Using an in vitro (intestinal sac) method this study aimed to address (a) the in vitro ability of Lactobacillus delbrueckii subsp. lactis to remain in the gastrointestinal tract of Atlantic salmon (Salmo salar L.) and (b) its ability to prevent cellular damage caused by successive incubation with Aeromonas salmonicida subsp. salmonicida the causative agent of furunculosis. Short in vitro incubation of salmon foregut with (TRITC)-labelled L. delbrueckii subsp. lactis showed that the probiont was able to colonize the enterocyte surface as studied by confocal microscopy. Furthermore, foregut incubated with the probiotic bacteria only, resulted in a healthy intestinal barrier whereas exposure to A. salmonicida disrupted its integrity. However, pre-treatment of salmon intestine with L. delbrueckii subsp. lactis prevented Aeromonas damaging effects. These results are promising in the context of the use of non-autochthonous probiotic bacteria as prophylactic agents against fish bacterial infections in the gastrointestinal tract. 相似文献
60.
M A Martín-Cabrejas L Jaime C Karanja A J Downie M L Parker F J Lopez-Andreu G Maina R M Esteban A C Smith K W Waldron 《Journal of agricultural and food chemistry》1999,47(3):1174-1182
The objective of this work was to evaluate extrusion cooking as a means to improve the nutritional properties of Phaseolus vulgaris L. that had been stored either at 42 degrees C and 80% relative humidity for 6 weeks or for periods >1 year in cereal stores in tropical conditions. Storage under these conditions resulted in an increase in cooking time increased (7.7- and 12-fold, respectively) as a result of development of the hard-to-cook (HTC) defect. Single-screw extrusion of the milled beans was carried out at four barrel temperatures and two moisture contents. The extrudate bulk density and water solubility index decreased with increasing temperature, whereas the water absorption index increased due to the higher proportion of gelatinized starch in the extruded samples. Both fresh and HTC beans contained nutritionally significant amounts of lectins, trypsin, and alpha-amylase inhibitors, which were mostly inactivated by extrusion. Extrusion also caused a considerable redistribution of insoluble dietary fiber to soluble, although the total dietary fiber content was not affected. Changes in solubility involved pectic polysaccharides, arabinose and uronic acids being the main sugars involved. Stored beans subjected to extrusion cooking showed physical and chemical characteristics similar to those of extrudates from fresh beans. 相似文献