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131.
Characterization of bioactive plant ellagitannins by chromatographic, spectroscopic and mass spectrometric methods 总被引:1,自引:0,他引:1
Ellagitannins are widely distributed plant polyphenols showing potent anti-herbivore activities, but rather complex chemical structures. Here we show how ellagitannins with different structures can be efficiently characterized from plant extracts by utilizing the information obtained from four universal methods used for ellagitannin analysis: Sephadex LH-20 gel chromatography, high-performance liquid chromatography, ultraviolet spectroscopy, and mass spectrometry. We show that by combining the information obtained from the ellagitannins’ chromatographic elution order, specific shapes of the ultraviolet spectra, molecular masses and characteristic mass spectral fragmentations, it is possible to classify these polyphenols into different ellagitannin sub-groups, and even characterize the structures within the sub-groups. These findings aid in the fast screening of complex plant samples for their ellagitannin composition without having to isolate compounds for individual characterization. 相似文献
132.
Austen W. Head Johanna S. Hardin Stephen C. Adolph 《Environmental and Ecological Statistics》2012,19(2):127-137
Estimates of animal performance often use the maximum of a small number of laboratory trials, a method which has several statistical disadvantages. Sample maxima always underestimate the true maximum performance, and the degree of the bias depends on sample size. Here, we suggest an alternative approach that involves estimating a specific performance quantile (e.g., the 0.90 quantile). We use the information on within-individual variation in performance to obtain a sampling distribution for the residual performance measures; we use this distribution to estimate a desired performance quantile for each individual. We illustrate our approach using simulations and with data on sprint speed in lizards. The quantile method has several advantages over the sample maximum: it reduces or eliminates bias, it uses all of the data from each individual, and its accuracy is independent of sample size. Additionally, we address the estimation of correlations between two different performance measures, such as sample maxima, quantiles, or means. In particular, because of sampling variability, we propose that the correlation of sample means does a better job estimating the correlation of population maxima than the estimator which is the correlation of sample maxima. 相似文献
133.
134.
Nini Johanna Cadena Camilo Rey Marcela Hernández-Hoyos J. Darío Sánchez Stanislas Teillaud Nestor Ardila Juan A. Sánchez 《Marine Biology》2010,157(5):1003-1010
Branching growth is present both in plants and animals, either marine or terrestrial. Although cellular and other modular
levels of organization in plants and animals have evolved through different molecular and physiological mechanisms, several
aspects of their branching modular system and morphology are similar. We studied vessel organization and colony integration,
in order to comprehend underlying relationships between different structural components in a gorgonian coral network. The
theoretical formalism was validated in the gorgonian coral Eunicea mammosa (Plexauridae, Octocorallia) in Belize. As in vascular plants, these colonial animals create a complex network of connections
among modular branches integrated in stem canals downstream toward the base. A new formalism is proposed for describing gorgonian
branching. A global property of a colony is for instance the size of its base or its weight whereas a local property is the
size of branch in a particular place of the colony. However, a global property is not the simple addition of local modular
properties, as the case of stem canals in the colony base. Theoretically, the process of branching is tightly intertwined
with the internal network organization. The colony network centralization is driven by a linear relationship between the total
number of branches and the stem canals at the base of the colony. If stem canals play important roles in the transport of
nutrients throughout the colony and the biomechanical support from the base up to the tips, we can assume that there is an
underlying association between the number of stem canals at the base and the number of for example, terminal branches. These
associations may provide new findings that extend our understanding of the functional organization of tree-like networks in
octocorals and their vascular systems. The idea that the external components of a tree-like plant network are directly correlated
and connected down to the main trunk seems to be analogous in an animal system. 相似文献
135.
136.
Johanna Christian Lee M. Frank Rob Olivier Ghislain Stphane Teresa Pinto Nadine Irina 《Environmental Science & Policy》2009,12(5):562-572
The goal oriented framework (GOF) for indicators has been developed as part of a comprehensive research project developing computerised tools for integrated assessment of the effects of new policies or technologies on agricultural systems (SEAMLESS-IF). The ambition has therefore been to create an indicator framework where the environmental, economic and social dimensions of sustainable development can be related to each other in a consistent way. Integrated assessment tools rely on such frameworks to capture and visualise trade-offs (antagonisms or synergies) among indicators between and within the three dimensions of sustainable development. The specific aims of this paper are to (i) present the GOF (ii) present how the GOF can be used to select indicators within the integrated assessment framework SEAMLESS-IF and (iii) discuss the advantages and limitations with the proposed approach. We show that the GOF has several advantages. Its major rewards are its relative simplicity and the possibility to link indicators to policy goals of each dimension of sustainability and thereby facilitate the comparison of the impacts of the new policy on the different dimensions. Another important feature of the GOF is its multi-scale perspective, which will enable the comparison of effects of a new policy between scales. Yet, as typical for all indicator frameworks, the GOF has also biases either instigated by the issues the included models cover or by the stakeholders’ selection of indicators. However, due to the way the GOF and its indicators are technically implemented in SEAMLESS-IF, it can easily be extended and include new indicators to increase and update its policy relevance. 相似文献
137.
Ivonne Bedei Tascha Gehrke Karl-Philipp Gloning Matthias Meyer-Wittkopf Daria Willner Martin Krapp Alexander Scharf Jan Degenhardt Kai-Sven Heling Peter Kozlowski Kathrin Trautmann Kai M. Jahns Annegret Geipel Jan-Erik Baumüller Lucas Wilhelm Ingo Gottschalk Andreas Schröer Alexander Graf Aline Wolter Johanna Schenk Axel Weber Ignatia B. Van den Veyver Roland Axt-Fliedner 《黑龙江环境通报》2023,43(2):192-206
Objective
We aimed to investigate how the presence of fetal anomalies and different X chromosome variants influences Cell-free DNA (cfDNA) screening results for monosomy X.Methods
From a multicenter retrospective survey on 673 pregnancies with prenatally suspected or confirmed Turner syndrome, we analyzed the subgroup for which prenatal cfDNA screening and karyotype results were available. A cfDNA screening result was defined as true positive (TP) when confirmatory testing showed 45,X or an X-chromosome variant.Results
We had cfDNA results, karyotype, and phenotype data for 55 pregnancies. cfDNA results were high risk for monosomy X in 48/55, of which 23 were TP and 25 were false positive (FP). 32/48 high-risk cfDNA cases did not show fetal anomalies. Of these, 7 were TP. All were X-chromosome variants. All 16 fetuses with high-risk cfDNA result and ultrasound anomalies were TP. Of fetuses with abnormalities, those with 45,X more often had fetal hydrops/cystic hygroma, whereas those with “variant” karyotypes had different anomalies.Conclusion
Both, 45,X or X-chromosome variants can be detected after a high-risk cfDNA result for monosomy X. When there are fetal anomalies, the result is more likely a TP. In the absence of fetal anomalies, it is most often an FP or X-chromosome variant. 相似文献138.
Johanna J. Vollenweider Ron A. Heintz Lawrence Schaufler Robert Bradshaw 《Marine Biology》2011,158(2):413-427
Quantifying the nutritional quality of forage fish is integral for understanding upper trophic levels as forage fish are the
dominant prey for top predator fish, marine mammals, and sea birds. Many existing reports documenting body composition of
forage species are not comparable due to confounding effects. This study systematically assessed the variability in proximate
composition and energy content of 16 forage species in southeastern Alaska (57.2626 N/133.7394 W) between 2001 and 2004. Variation
in energy and lipid contents was related to habitat, epipelagic planktivores varying most, mesopelagics intermediate, and
demersal species relatively invariable. Season was the greatest source of variation as a result of short growing seasons at
high latitude and energy allocation strategies for reproduction and growth. Among species that varied seasonally, energy and
lipid increased over summer and declined during winter. Annual differences in body composition occurred during periods of
peak energy content. Sampling recommendations and guidance for bioenergetics models are provided. 相似文献
139.
Johansson MV Forslund J Johansson P Samakovlis E 《Journal of environmental management》2011,92(4):1303-1313
The major aim of this paper is to analyze how government funding affects the pace of progress in four states of the remediation process of contaminated sites, from basic risk classification to cleanup. We introduce a methodological framework that takes into account the unobserved site-heterogeneity and simultaneously models duration in the different states. The results show that although site-heterogeneity contributes to make remediation a slow process, the third state, from the elaborate risk classification to the cleanup start, is a particular bottleneck. Even if government funding can speed up the process at this state, the effect is minuscule compared to the amounts of funding required. Thus, there is a need for policy to also focus on other barriers to remediation. 相似文献
140.
Sediment-based investigation of naturally or historically eutrophic lakes -- implications for lake management 总被引:3,自引:0,他引:3
Implementation of the EU Water Framework Directive will call for new lake monitoring and management strategies. Therefore, different methods need to be tested in order to achieve reliable assessment of lake background conditions and water quality. Sediment-based techniques provide one such tool for lake management. In this work, 10 lakes, presumed to be naturally eutrophic, were investigated with a paleolimnological short core study. The aim of the study was to examine the composition of the diatom assemblages in their natural state, estimate their change over time and assess the background nutrient levels. One sediment profile from each lake was divided into six sub-samples that were analyzed for diatoms (60 samples). Diatom-based inference models were applied to reconstruct the past total phosphorus concentration and assess the eutrophication. The results indicated that all the lakes studied had already been nutrient-rich before the impact of modern agriculture. However, diatom assemblages have changed remarkably over time and total phosphorus concentrations have generally increased, so at present only two of the study lakes are close to their natural status. This suggests that naturally eutrophic lakes will probably require management actions to fulfill the new directive requirements in the future. 相似文献