1,720,954 research outputs found
Chang Y. T., and F. H. Chu,2011,Molecular cloning and characterization of monoterpene synthases from Litsea cubeba (Lour.) Persoon.
No full textMolecular Cloning and Characterization of Monoterpene Synthases from Litsea cubeba (Lour.) Persoon
No full text山胡椒 (Litsea cubeba (Lour) Persoon)，為台灣常見的闊葉植物，其精油可應用於食品以及醫藥製品，具消腫、止痛等功效。據前人研究指出，山胡椒精油的單萜成分具有良好的抗發炎活性。本試驗採集山胡椒不同組織，利用基因資料庫中木本闊葉植物之單萜合成酶基因序列設計退化性引子對，並藉由聚合酶連鎖反應及 cDNA 末端快速擴增法，得到三個山胡椒單萜合成酶基因全長，分別命名為LcTPS1、LcTPS2與LcTPS3，其轉譯區序列長度分別為 1750 bp、1743 bp、與1743 bp，其中LcTPS2與LcTPS3兩個核酸序列具高達 97％ 的相似度。為了解該基因在植物體之表現型態，本研究利用反轉錄聚合酶連鎖反應與即時聚合酶連鎖反應觀察三個單萜合成酶基因在山胡椒各部位組織的表現狀況，結果顯示LcTPS1在雄樹的葉子中表現量最高，於未成熟果的表現量最低；LcTPS2在成熟果的表現量最高，於雌樹的葉子表現量最低；而LcTPS3則在未成熟果表現量最高，於枝條的表現量最低。由鄰近連接演化樹分析結果，三個 LcTPS 基因皆坐落在TPS-b的分群之中，其中 LcTPS2 與 LcTPS3 被分類在同一組次分群中而與LcTPS1區分開來。而由蛋白質預測分析結果，LcTPS1之蛋白質大小約為67.1 kDa，而LcTPS2與LcTPS3則約為67.4 kDa。將LcTPS1、LcTPS2與LcTPS3基因分別構築於大腸桿菌 (Escherichia coli BL21) 用之載體 pTYB12 得到可溶部蛋白質，以體外反應的方式驗證 LcTPS1 產物為反式-蘿勒烯；LcTPS2 產物為α-側柏烯；LcTPS3 則具雙重功能，其產物為α-側柏烯與 (+)-香檜烯。目前已有研究指出α-側柏烯與(+)-香檜烯具有良好的上真菌活性，反式-蘿勒烯具有良好的抗氧化活性。Mountain spicy tree (Litsea cubeba (Lour) Persoon) is a primitive evergreen tree in Taiwan. Previous studies had showed that the fruit of L. cubeba possess the dispels rheumatism, detumescence, detoxify, and analgetic effect, and in the essential oil of L. cubeba, the dominant component is monoterpenes, which have anti-inflammatory activity. To elucidate the biosynthesis of monoterpenes which have bioactivity in L. cubeba, three cDNAs corresponding to monoterpene synthase genes expressed in different tissues of L. cubeba were isolated, and the corresponding enzymes were functionally characterized in vitro. To isolate cDNAs corresponding to monoterpene synthases of L. cubeba, two pairs of primers were designed according to the monoterpene synthases of woody plant. Monoterpene DNA sequences were collected from NCBI database, and polymerase chain reaction (PCR), rapid amplication of cDNA end (RACE) were used for getting full sequence of L. cubeba monoterpene synthases. These genes obtained were named LcTPS1, LcTPS2, and LcTPS3, which have 1749 bp (base pair), 1743 bp and 1743 bp coding region respectively. To investigate expression levels of LcTPS1, LcTPS2, and LcTPS3 at different tissues of L. cubeba, reverse transcription PCR and real-time PCR were used for detection of transcript levels for all three genes at different tissues. The results showed that LcTPS1 genes were most prominent in the leaf of the male trees, LcTPS2 genes were most prominent in development fruit tissue, and LcTPS3 genes were prominent in mature fruit tissue. Phylogenetic analyses indicated that LcTPS1, LcTPS2, and LcTPS3 all belonged to TPS-d terpene family, which represents the angiosperm monoterpene synthase genes. To functionally characterize corresponding enzymes of LcTPS1, LcTPS2, and LcTPS3 in vitro, LcTPS1, LcTPS2, and LcTPS3 were expressed in E. coli protein expression system for pure protein. Recombinant LcTPS1 converted geranyl diphosphate to trans-ocimene, LcTPS2 converted geranyl diphosphate to α-thujene while LcTPS3 is a bifunctional enzyme that converted geranyl diphosphate to α-thujene and (+)-sabinene respectively. According to previous studies, α-thujene and sabinene possess great anti-fungal activity and trans-ocimene possesss antioxidant activity
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
