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排序方式: 共有257条查询结果,搜索用时 265 毫秒
1.
Nilsson Anna L. K. Skaugen Thomas Reitan Trond L’Abée-Lund Jan Henning Gamelon Marlène Jerstad Kurt Røstad Ole Wiggo Slagsvold Tore Stenseth Nils C. Vøllestad L. Asbjørn Walseng Bjørn 《BMC ecology》2020,20(1):1-12
While nitrogen and carbon stable isotope values can reflect ecological segregation, prey choice and spatial distribution in seabirds, the interpretation of bulk stable isotope values is frequently hampered by a lack of isotopic baseline data. In this study, we used compound-specific isotope analyses of amino acids (CSIA-AA) to overcome this constraint and to study interspecific differences, seasonal and historical changes in trophic positions of five seabird species, three penguins and two petrels, from a sub-Antarctic seabird community. CSIA-AA allowed comparing trophic positions of seabirds with temperate and polar distributions. Gentoo and Magellanic penguins had the highest trophic positions during the breeding season (3.7 and 3.9), but decreased these (2.9 and 3.3) during the feed-up for moult. Intra-specific differences were also detected in Thin-billed prions, where carbon isotope values clearly separated individuals with polar and temperate distributions, both in the breeding and interbreeding periods. Thin-billed prions that foraged in polar waters had lower trophic positions (3.2) than conspecifics foraging in temperate waters (3.8). We further investigated historical changes by comparing museum samples with samples collected recently. Our pilot study suggests that Rockhopper penguins, Magellanic penguins and Thin-billed prions with temperate non-breeding distributions had retained their trophic levels over a 90–100 year period, while Gentoo penguins and Thin-billed prions with polar non-breeding distributions had decreased trophic levels compared to historical samples. In contrast, Wilson’s storm-petrels had slightly increased trophic levels compared to samples taken in 1924–1930. We applied compound-specific stable isotope analyses across a range of contexts, from intra-specific comparisons between stages of the breeding cycle to inter-specific seabird community analysis that would not have been possible using bulk stable isotope analyses alone due to differences in isotopic baselines. 相似文献
2.
Comparison of antioxidant potency of commonly consumed polyphenol-rich beverages in the United States 总被引:4,自引:0,他引:4
Seeram NP Aviram M Zhang Y Henning SM Feng L Dreher M Heber D 《Journal of agricultural and food chemistry》2008,56(4):1415-1422
A number of different beverage products claim to have antioxidant potency due to their perceived high content of polyphenols. Basic and applied research indicates that pomegranate juice (PJ), produced from the Wonderful variety of Punica granatum fruits, has strong antioxidant activity and related health benefits. Although consumers are familiar with the concept of free radicals and antioxidants, they are often misled by claims of superior antioxidant activity of different beverages, which are usually based only on testing of a limited spectrum of antioxidant activities. There is no available direct comparison of PJ's antioxidant activity to those of other widely available polyphenol-rich beverage products using a comprehensive variety of antioxidant tests. The present study applied (1) four tests of antioxidant potency [Trolox equivalent antioxidant capacity (TEAC), total oxygen radical absorbance capacity (ORAC), free radical scavenging capacity by 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP)]; (2) a test of antioxidant functionality, that is, inhibition of low-density lipoprotein (LDL) oxidation by peroxides and malondialdehyde methods; and (3) evaluation of the total polyphenol content [by gallic acid equivalents (GAEs)] of polyphenol-rich beverages in the marketplace. The beverages included several different brands as follows: apple juice (3), a?aí juice (3), black cherry juice (3), blueberry juice (3), cranberry juice (3), Concord grape juice (3), orange juice (3), red wines (3), iced tea beverages (10) [black tea (3), green tea (4), white tea (3)], and a major PJ available in the U.S. market. An overall antioxidant potency composite index was calculated by assigning each test equal weight. PJ had the greatest antioxidant potency composite index among the beverages tested and was at least 20% greater than any of the other beverages tested. Antioxidant potency, ability to inhibit LDL oxidation, and total polyphenol content were consistent in classifying the antioxidant capacity of the polyphenol-rich beverages in the following order: PJ>red wine>Concord grape juice>blueberry juice>black cherry juice, a?aí juice, cranberry juice>orange juice, iced tea beverages, apple juice. Although in vitro antioxidant potency does not prove in vivo biological activity, there is also consistent clinical evidence of antioxidant potency for the most potent beverages including both PJ and red wine. 相似文献
3.
Hop with powdery mildew [HPM: caused by Podosphaera macularis (Wallr.) U. Braun & S. Takam.] results in significant losses in hop production by reducing yield and quality. One means of increasing yield and quality is the production of resistant hop lines. Breeding for resistance can be significantly improved and accelerated by use of marker-assisted selection. The objective of this preliminary study was to identify QTLs and markers for genetic resistance to HPM. A bi-parental mapping population between the resistant line “Newport” and susceptible line ‘21110M’. Phenotypic data was scored under controlled greenhouse conditions. Significant differences among offspring were observed and disease resistance did not follow a distinct binomial distribution, suggesting quantitative genetic control. Genotyping-by-sequencing resulted in approximately 375 K SNP markers, which were filtered down to 2263 markers mapped to 10 linkage groups. Interval Mapping identified four QTLs with one on linkage group 1 and three located on linkage group 6. Composite interval mapping identified three QTLs, all located on linkage group 6. Mixed linear models identified 15 markers associated with expression of resistance to HPM. Three of these 15 SNPs were also identified in QTL-CIM analysis. Evaluation of the scaffolds containing the significant SNP markers identified seven putative genes—several of which appear involved in disease resistance in other plant species. The SNP markers identified in this study still require validation in unrelated populations prior to implementation in breeding programs. 相似文献
4.
OBJECTIVE: To determine whether the bispectral index (BIS) can be used as an indicator of degree of CNS depression in isoflurane-anesthetized horses. ANIMALS: 10 Standardbred and 6 Norwegian cold-blooded trotter stallions admitted for routine castration. PROCEDURE: A 2-channel referential electrode configuration was used to record EEG for calculation of BIS by the EEG monitor. The BIS was calculated before (awake) and after (sedated) administration of detomidine (0.01 mg/kg of body weight, IV) and butorphanol (0.01 mg/kg, IV). Anesthesia was induced with ketamine hydrochloride (2.5 mg/kg, IV) and diazepam (0.04 mg/kg, IV) and maintained with isoflurane delivered in oxygen. The BIS was calculated after 30 minutes of equilibration at an end-tidal isoflurane concentration of 1.4% (n = 8) or 1.9% (8) and recorded continuously during surgery. RESULTS: Bispectral index was significantly less in sedated and anesthetized horses, compared with awake horses. However, BIS was not significantly different between sedated and anesthetized horses. Mean BIS in horses anesthetized at 1.9% isoflurane was significantly greater, compared with horses anesthetized at an end-tidal concentration of 1.4%. Four horses in the 1.4% group moved during surgery, and BIS increased immediately prior to movement in 2 of these horses. CONCLUSIONS AND CLINICAL RELEVANCE: BIS is not a precise indicator of degree of CNS depression in isoflurane-anesthetized horses. Thus, determination of BIS may not be a useful technique for monitoring anesthetic depth in isoflurane-anesthetized horses. 相似文献
5.
Because veal lean color continues to be a primary factor that determines veal carcass value and is typically assessed by subjective means, it is important to explore objective methods for color assessment. Objective and subjective evaluations of veal flank and breast lean color were compared as predictors of longissimus lean color at 24 h postmortem. One hundred fifty special-fed Holstein veal calves were Kosher-slaughtered with blood samples collected upon exsanguination and analyzed for hematocrit and hemoglobin content. Lean color was evaluated in the flank and breast at 0, 6, 12, and 24 h postmortem. Color of the longissimus was evaluated at 6 h, when possible, and at 24 h. A panel of three trained individuals used a 5-point color standard developed in the Netherlands to visually evaluate lean color. A Minolta Chromameter CR-300 was used to obtain L*, a*, and b* values. A plant employee assigned packer grades at slaughter. Temperature and pH were also measured at each time period. Hemoglobin was more highly correlated than hematocrit with colorimeter values. Hemoglobin levels correlated well with a* values of the flank at 0 h postmortem (r = 0.52) although the correlation declined at 24 h (r = 0.30). The correlation between packer grades and 24-h visual loin color was r = 0.41. Visual loin color at 24 h postmortem was selected as the predicted variable for regression analysis. Temperature and pH did not contribute significantly to any prediction equations. The equation using breast L*, a*, and b* values at 24 h postmortem to predict 24-h loin color gave a higher prediction coefficient (R2 = 0.44) than the corresponding equation using 0-h breast values (R2 = 0.28). Objective measurement of lean color may be useful in veal carcass grading because it is more precise than subjective methods and would allow for uniformity among processing plants. 相似文献
6.
Henning K Schares G Granzow H Polster U Hartmann M Hotzel H Sachse K Peters M Rauser M 《Veterinary microbiology》2002,85(3):285-292
Characteristics of an intracellularly growing micro-organism isolated from an aborted bovine foetus are described. The organism replicated within cytoplasmic vacuoles, was resistant to penicillin and exhibited structural characteristics compatible with Waddlia chondrophila. An ELISA specific for Chlamydia spp., immunofluorescence tests using antibodies directed against Chlamydia spp. or Simkania negevensis, and PCR using Chlamydia-specific primers showed that the agent was distinct from Chlamydiae or S. negevensis. Determination of 16S and partial 23S ribosomal RNA gene sequences in combination with the PCR results and the morphological, antigenic and developmental characteristics provided evidence that the isolate 2032/99 can be classified as W. chondrophila or a closely related organism. 相似文献
7.
Stefan Fleck Nathalie Cools Bruno De Vos Henning Meesenburg Richard Fischer 《Annals of Forest Science》2016,73(4):945-957
Key message
Aggregated, consolidated, and derived soil physicochemical data of 286 ICP Forests Level II plots were completed with soil hydraulic properties for integrated use with forest monitoring data. Database access should be requested at http://icp-forests.net . Metadata associated available at https://metadata-afs.nancy.inra.fr/geonetwork/apps/georchestra/?uuid=153e599e-6624-4e2b-b862-8124386ea9cd&hl=engContext
The ICP Forests database is one of the most comprehensive forest ecosystem datasets in Europe and contains the accumulated results of more than two decades of harmonised forest monitoring all over Europe.Aims
The aim of this paper is to share knowledge on the ICP Forests Level II soil data for broader use among forest scientists.Methods
After standard analysis, quality checks, aggregation, and calculation of derived variables (e.g. nutrient stocks, base saturation, C:N ratio, and water retention parameters), data have been gathered into a static database (AFSCDB.LII.2.2), which will be updated to new versions as soon as new measurements become available.Results
The database provides a basis for the combined evaluation of up to 130 unique soil variables of 286 plots with dynamic data on tree growth, ground vegetation, foliar chemistry, crown condition, tree phenology, leaf area index, ozone injury, litterfall, soil solution chemistry, deposition, ambient air quality, and meteorological data assessed on the same plots.Conclusion
The unprecedented comprehensiveness and level of detail in this newly aggregated database may overcome existing restrictions so far impeding the realisation of large-scale forest ecosystem studies in Europe.8.
9.
David J. Lohman Krista K. Ingram Kevin Winker Robert G. Moyle Perry S. Ong Thomas M. Braile Dwi Astuti 《Biological conservation》2010,143(8):1885-1890
Mistakenly classifying morphologically cryptic endemic species as populations of widespread species potentially interferes with the conservation of biodiversity because undetected endemics that are imperilled may lack appropriate protection. It also impedes the reconstruction of the evolutionary history of a taxon by obscuring the number and distributional limits of species. Here, we present genetic and phylogenetic evidence corroborated by morphology that Philippine populations of seven widespread, non-migratory passerine birds might represent unrecognized, distinct species. An extrapolation based on this finding suggests that the proportion of endemic bird species in the Philippines could be much higher than currently estimated. This high degree of cryptic diversity in a well-studied, volant taxon implies that large numbers of unrecognized species can be expected in less thoroughly studied groups. We predict that genetic investigations of insular populations of widespread species will frequently reveal unrecognized island endemics, and because of the vulnerability of island habitats and their biota, these taxa may be particularly susceptible to extinction. 相似文献
10.