1,721,026 research outputs found
Screening for anthocyanins and polyphenols in red and blue potatoes for evaluation of differences in anthocyanin biosynthesis
Get PDFPotato is among the most important staple foods worldwide. Pigmented varieties can provide a major quantitative source of anthocyanins which are considered to have health-promoting effects, linked to their antioxidant capacity. This promotes an increasing interest in anthocyanin rich colored potatoes as functional food from the food industry, nutritional science and consumers. Pigmented potatoes show a tremendous variability in anthocyanin content and in their specific composition and supply a suitable model system for investigation of anthocyanin side chain regulation in crops, which is the purpose of our study.
Our aim includes deepening the knowledge of flavonoid biosynthesis in red and blue potatoes. We initially performed an LC-MS (liquid chromatography coupled to mass spectrometry) analysis to elucidate the anthocyanin and polyphenol composition of 57 colored potato cultivars. Two tissues of potato tubers, namely flesh and peel, where analyzed separately. Based on the obtained anthocyanin and polyphenol profiles 19 contrasting potato cultivars have been selected for further in-depth studies. Quantification of 21 individual anthocyanins and 43 polyphenols was done in a subsequent MRM (multiple reaction monitoring) analysis. The selected potato cultivars harbor anthocyanins with different backbone and different acyl and sugar conjugates. This observation is supposed to be reflected in the genetic background of the anthocyanin biosynthetic pathway. Results of the LC-MS/MRM based annotation, as well as the correlation of anthocyanin and polyphenol content might hint to phylogenetic relations between the cultivars.
Further studies will include comparative analysis of quantitative differences in anthocyanin content and transcript expression of anthocyanin biosynthesis key genes, validated also by enzyme expression and enzyme activity analyses, in different developmental stages. Additionally, we will study possible promoter regulations of anthocyanin biosynthesis genes and the relevance of transcription factors for regulation of the observed anthocyanin profiles
Investigations of the regulation of anthocyanin side chain decoration in colored potatoes
No full textPotato is among the most important staple foods worldwide. Pigmented varieties can provide a major quantitative source of anthocyanins which are considered to have health-promoting effects, linked to their antioxidant capacity (Prior 2003). This promotes an increasing interest in anthocyanin rich 'blue' potatoes as functional food from the food industry, nutritional science and consumers. Pigmented potatoes show a tremendous variability in anthocyanin content and in their specific composition and supply a suitable model system for investigation of anthocyanin side chain regulation in crops.
In our studies we aim at investigation of regulatory mechanisms controlling side chain decoration of anthocyanins in potato. We selected 60 different varieties of cultivated anthocyanin pigmented potatoes from the Gross Luesewitz Potato Collections of the IPK Genebank (GLKS) to perform LC-MS based anthocyanin profile analysis of extracts from potato flesh and peel, respectively. Further assortment was due to interesting profiles showing only a few distinct peaks for anthocyanins different in side chain decoration. We will present results for the examination of anthocyanin composition including metabolite profiling and phytochemical characterization by means of an LC-MS based approach. Selected lines will be further monitored for their anthocyanin profiles during tuber development.
Further studies will include comparative gene expression analysis in different developmental stages to analyze quantitative differences in anthocyanin biosynthesis key gene expression, validated also by enzyme expression analyses. Additionally, we will study promoter regulation. We will create RNAi lines to study promoter and gene function and the relevance of transcription factors for regulation of anthocyanin profiles
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Impact of Cyanidin-based anthocyanins on Ros Levels in human colon carcinoma cells
Get PDFAnthocyanins are able to scavenge ROS and thus protect against free radicals and cell oxidation. The nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2) is considered as a key sensor for cellular ROS. In its active form Nrf2 translocates into the nucleus, binds to the antioxidant responsive element (ARE) triggering the transcription of a wide variety of genes that are capable to protect the organism against xenobiotics and/or oxidative stress. Whether the pattern of different sugar moieties at the cyanidin (Cy) molecule affects the antioxidant properties differently in human colon cells was assessed with the dichlorofluorescein (DCF) assay. The bioactivity of naturally occurring anthocyanins such as cyanidin-3O-glucoside (Cy-3-glc), cyanidin-3O-sambubioside (Cy-3-sam), cyanidin-3O-sambubioside-5-glucoside (Cy-3-sam-5-glc) and cyanidin-3O-rutinoside (Cy-3-rut) were tested in colon carcinoma cells C2BBe1 at a concentration range of 0.01 - 200 μM. Cellular ROS levels were measured for 1h. The protective effect of anthocyanins against hydrogen peroxide induced oxidative stress was determined with a modified DCF assay, where cells were incubated with test compounds for 24h prior the addition of stressor.
All anthocyanins including the aglycon Cy caused a concentration-dependent reduction of ROS levels. Cy-3-glc and Cy-3-sam appeared to be the most potent antioxidants. Both anthocyanins were also able to protect colon cells from H2O2 -induced stress at 200 μM, indicating a potential activation of cellular defense systems such as the Nrf2 signaling pathway. All other test compounds were not protective. The position and number of glycosyl moieties as well as the type of glycoside, as most obvious for Cy-3-sam and Cy-3-rut, significantly impact the antioxidant activity of cyanidin derivatives in C2BBe1 cells
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Impact of a blackberry extract and single anthocyanins on the inflammatory response of human macrophage THP-1 cells
Get PDFAnthocyanins are considered to be beneficial and may protect from chronic inflammation. Thus, investigations on anthocyanin-rich extracts and single constituents are of great interest.
We investigated a blackberry extract, containing a spectrum of anthocyanins, in comparison to two sub-fractions comprising cyanidin-3-(6''-dioxalylglucoside) and cyanidin-3-(malonylglucoside), respectively, regarding their impact on inflammation-related cytokine expression and secretion in human macrophages.
Relative gene transcription and cytokine secretion of IL-6 and TNF-alpha were measured using qRT-PCR and cytokine bead-based immunoassay, respectively.
The THP-1 monocyte cells served as a cell model to mimic the inflammatory response. Therefor cells were differentiated with phorbol-12-myristate-13-acetate into macrophages which were pre-incubated with physiologically relevant concentrations of blackberry extract or single compounds. Subsequent stimulation with lipopolysaccharides from E.coli induced gene transcription and cytokine release.
Cyanidin-3-(malonylglucoside) had no impact on LPS-induced IL6 and TNF-alpha expression. In contrast, the blackberry extract and cyanidin-3-(6''-dioxalylglucoside) caused further stimulatory effects for the transcription and secretion of IL-6 at higher concentrations. The secretion of TNF-alpha was increased as well by both, yet with no impact on the transcript level after 3 h of incubation.
The results clearly show that single as well as combinatory effects might be of relevance for the immune-stimulatory impact of the blackberry extract
- …
