1,720,955 research outputs found
Analysis of AtGUS1 and AtGUS2 in Arabidopsis root apex by a highly sensitive TSA-MISH method
Full text linkA new highly sensitive whole-mount in situ hybridization method, based on tyramide signal amplification (TSA-MISH) was developed and a combined GFP detection and TSA-MISH procedure was applied for the first time in plants, to precisely define the spatial pattern of AtGUS1 and AtGUS2 expression in the root apex. β-glucuronidases (GUSs) belonging to the glycosyl hydrolases (GHs) 79 family, are widely distributed in plants, but their functional role has not yet been fully investigated. In the model system Arabidopsis Thaliana, three different AtGUS genes have been identified which encode proteins with putative different fates. Endogenous GUS expression has been detected in different organs and tissues, but the cyto-histological domains of gene expression remain unclear. The results here reported show co-expression of AtGUS1 and AtGUS2 in different functional zones of the root apex (the cap central zone, the root cap meristem, the staminal cell niche and the cortical cell layers of the proximal meristem), while AtGUS2 is exclusively expressed in the cap peripheral layer and in the epidermis in the elongation zone. Interestingly, both genes are not expressed in the stelar portion of the proximal meristem. A spatial (cortex vs. stele) and temporal (proximal meristem vs. transition zone) regulation of AtGUS1 and AtGUS2 expression is therefore active in the root apex. This expression pattern, although globally consistent with the involvement of GUS activity in both cell proliferation and elongation, clearly indicates that AtGUS1 and AtGUS2 could control distinct downstream process depending on the developmental context and the interaction with other players of root growth control. In the future, the newly developed approaches may well be very useful to dissect such interactions
Espressione dei geni GUS e UGT85A in Arabidopsis thaliana
No full textLe β-glucuronidasi (GUS) sono enzimi che catalizzano l’idrolisi del legame glicosidico fra l’acido β-glucuronico e altre molecole e sono suddivise in due famiglie: glicosil-idrolasi 2 e glicosil-idrolasi 79. Le β-glucuronidasi della famiglia 2, alle quali appartiene il GUS di E. coli largamente usato come gene reporter nei vegetali, sono note in un grande range di organismi, ma sembrano essere assenti nelle piante, nelle quali l’attività GUS endogena sembra associata a β-glucuronidasi della famiglia 79 (Eparanasi) (1).
In Arabidpopsis thaliana sono stati identificati e parzialmente caratterizzati tre diversi geni GUS (AtGUS1, AtGUS2 e AtGUS3), dei quali AtGUS1 e AtGUS2 mostrano elevata omologia.
A parte funzioni specifiche (2),coinvolgimento delle β-glucuronidasi è stato proposto nel processo di accrescimento cellulare per distensione e, in particolare, nell’allungamento dei peli radicali (3). E’ stato, inoltre, ipotizzato che β-glucuronidasi, agendo in coordinazione con glucuronisiltrasferasi (UGT) del gruppo 85A, siano responsabili della regolazione del ciclo cellulare (4,5). Uno studio più recente tuttavia ha messo in parte in discussione quanto emerso in precedenza riportando che nelle radici di plantule di Arabidopsis thaliana non è presente attività β-glucuronidasica (6).
In questo lavoro si è voluto approfondire lo studio dell’espressione dei geni GUS e UGT in Arabidopsis. Verifiche preliminari effettuate con PCR semiquantitativa hanno mostrato che, nonostante il gene AtGUS2 risulti espresso in modo più rilevante rispetto a AtGUS1 e AtGUS3, tutti e tre i geni AtGUS sono espressi, sia pure differenzialmente, in tutti gli organi della pianta. I geni AtUGT85A mostranoun pattern di espressione più differenziato rispetto ai geni AtGUS. AtUGT85A1, AtUGT85A2 e AtUGT85A4 risultano differenzialmente espressi nei vari organi della pianta, mentre AtUGT85A3 e UGT85A7 mostrano un’espressione organo specifica che coinvolge fiore e foglia
Utilizzando la tecnica di ibridazione in situ con sonde multiple recentemente messa a punto su campioni vegetali (7), l’espressione dei geni GUS è stata studiata anche a livello tissutale. A livello radicale , il pattern di espressione dei tre geni analizzati appare chiaramente differenziato: AtGUS1 e AtGUS2 sono espressi nell’epidermide, nella zona corticale e nella cuffia, mentre l’espressione di AtGUS3 è limitata all’epidermide. Sono in corso le analisi relative agli altri organi della pianta e, in particolare, fiore e polline. Analogo approccio verrà esteso ai geni AtUGT85 al fine di verificarne l’overlapping o meno con i domini istologici di espressione dei geni GUS e definirne eventuali correlazioni
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
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