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Advance in histochemistry, ultrastructure and secretion of glandular trichomes in Salvia dolomitica Codd.
No full textIn order to have better knowledge of African sages, we begun the study of some Salvia species (Serrato Valenti, 1997; Bisio et al., 1998; Bisio et al., 2001) belonging to the G species-group according to Hedge classification (1974). In the present work we examined the ultrastructure and the histochemistry of the glandular trichomes, and the essential oil and the exudate products of Salvia dolomitica Codd., a shrub, native of Transvaal, South Africa.
The leaves of S. dolomitica appeared covered by uniseriate non-glandular trichomes and glandular trichomes. The latter occurred as peltate and capitate (Bisio et al., 2001).
The histochemistry of peltate hairs evidenced a secretion with abundant hydrophobic substances, but also small quantities of hydrophilic substances (polysaccharides, flavonoids, phenols, essential oil, triterpenoids). The ultrastructural observations are consistent with the histochemical ones; indeed, the former showed abundant plastids and smooth endoplasmic reticulum (SER), typical organelles of lipophilic secreting cells, as observed in many other trichomes secreting lipophilic substances. SER can also be responsible for flavonoid secretion, as indicated also by Schopker et al. (1995).
Two types of capitate hairs, depending on the number of the secreting and stalk cells, were observed. The cytoplasm of type I presented numerous Golgi stacks, plastids and dilated ER, that are organelles respectively responsible for secretion of polysaccharides, terpenes and also flavonoids. Indeed, histochemical observations indicated a complex secretion, in which phenolic compounds, polysaccharides and terpenes were present. Also in type II trichomes the histochemical and ultrastructural observations indicated a complex secretion with phenolic compounds, polysaccharides and terpenes, but probably the release of secretion occurs in a different way and at a different time.
In S. dolomitica the essential oil was mainly constituted by monoterpene hydrocarbons, followed by oxigenated monoterpenes and sesquiterpene hydrocarbons. The main components of the oil were represented by substances that are often described for other Salvia species, 1,8-cyneol, limonene, -3-carene, -pinene and -caryophyllene.
The analysis of leaf surface extract identified abietane diterpenoids: carnosol and 7-methoxirosmanol suggesting that these products could be good taxonomic markers.
BISIO A, FONTANA N, ROMUSSI G, DE TOMMASI N. 1998. Pharmazie 53: 210-211.
BISIO A, ROMUSSI G, MALECI L, CORALLO A, ZAPPA E, PROFUMO P. 2001. 96°Congresso della Società Botanica Italiana – Varese 26-28 settembre 2001. 145.
HEDGE IC. 1974. Notes from the Royal Botanic Garden, Edinburgh. 33: 1-118.
SCHÖPKER H, KNEISEL M, BEERHUES L, ROBENEK H, WIERMANN R. 1995. Planta 196: 712-719.
SERRATO-VALENTI G, BISIO A, CORNARA L, CIARALLO G. 1997. Annals of Botany 79: 329-336
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
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
Citral-containing essential oils as potential tyrosinase inhibitors: A bio-guided fractionation approach
No full textExcessive melanin production causes serious dermatological conditions as well as minor aesthetic problems (i.e., freckles and solar lentigo). The downregulation of tyrosinase is a widespread approach for the treatment of such disorders, and plant extracts have often proven to be valuable sources of tyrosinase inhibitors. Citral (a mixture of neral and geranial) is an important fragrance ingredient that has shown anti-tyrosinase potential. It is highly concentrated in the essential oils (EOs) of Cymbopogon schoenanthus (L.) Spreng., Litsea cubeba (Lour.) Pers., Melissa officinalis L., and Verbena officinalis L. However, only L. cubeba EO has been investigated for use as a potential skin-whitening agent. This work evaluates the in vitro tyrosinase inhibitory activity of these EOs and studies, using bio-assay oriented fractionation, whether their differing chemical compositions influence the overall EO inhibitory activities via possible synergistic, additive, and/or competitive interactions between EOs components. The inhibitory activity of C. schoenanthus EO and that of M. officinalis EOs, with negligible (+)-citronellal amounts, were in-line with their citral content. On the other hand, L. cubeba and V. officinalis EOs inhibited tyrosinase to considerably greater extents as they contained beta-myrcene, which contributed to the overall EO activities. Similar observations were made for M. officinalis EO, which bears high (+)-citronellal content which increased citral activity
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
Phytochemical and biomolecular analyses of four wild edible Carduus species from Sardinia.
No full textChapter 10: Chemometrics: Basic principles and applications
No full textThis chapter will be devoted to chemometrics in the multivariate design of the experiments and in data treatment in gas chromatography. Basic principles will be given on the most commonly used approaches, along with applications in the field of one-dimensional and multidimensional gas chromatography. This chapter shows how suitable multivariate statistical methods can be of great support in specific food applications such as confirmation of authenticity, geographical origin, quality, evaluation of technological processes, and so on, exploiting its potential also in the omics field, such as "foodomics"
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