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Latex lipase of Euphorbia characias L.: An aspecific acylhydrolase with several isoforms
No full textThe objective of the present work was to contribute to the understanding of the physiological role of latex lipolytic activity in Euphorbia characias. To this end, the acid and basic lipolytic activity of E. characias latex, as well as the substrate specificity on various triacylglycerols, were measured during the plant's vegetative and reproductive stages. Both activities appeared to increase during the reproductive stage and to peak at the beginning of the vegetative stage, when new leaves and branches are formed. For the first time, the phospholipolytic and esterase activity of E. characias latex is also reported. An extraction method in aqueous medium with the zwitterionic detergent CHAPS was successfully used to extract lipolytic activity from latex. Extraction permitted the selective recovery of a single protein spot, with a molecular weight of 37 kDa, and presumably made of several acid isoforms which retained both lipolytic and phospholipolytic activity. The biochemical results suggest that lipolytic and phospholipolytic activity could depend on a single hydrolytic enzyme with several isoforms, equally expressed throughout the biological cycle of the plant. On the basis of the obtained results, we hypothesise that the E. characias latex lipase should be considered as an aspecific acylhydrolase with a combined lipase/phospholipase A activity
Synthesis and/or accumulation of bioactive molecules in the in vivo and in vitro root
No full textRoots of many species are studied because of the presence of high-value biclactive molecules, yet few studies have attempted to determine the biosynthetic pathways of these compounds or the way in which synthesis is regulated. The presence of secondary metabolites in the root does not necessarily mean that this organ is also the site of synthesis. Thus the identification of organ-specific intermediate precursors and key enzymes is important for understanding the biosynthetic pathway and the regulation of biclactive molecules. This knowledge could allow researchers to predict the suitability of in vitro systems, such as regenerated roots and hairy roots, for producing the molecules of interest. In the present review, the production of biclactive molecules in in vivo roots is compared to that in in vitro untransformed and transformed roots, concentrating on recent developments in the study of the biosynthesis of the anti-cancer alkaloid camptothecin in Camptotheca acuminata Decne. The results of a recent study performed in our laboratory on the production of camptothecin and other secondary metabolites in in vivo and in vitro C. acuminata roots are also presented
Plant latex lipases: physiological role and applications
No full textLipases are natural catalysts widely employed to structure various lipids, fats and oils in the cosmetic, pharmaceutical and food industries. Despite their high potential in lipid biotechnology, current application of microbial lipases has been limited owing to high costs and limited availability. During the last two decades, research efforts have been directed towards the identification of low cost and GRAS (Generally Recognized As Safe) lipases sources. Plant lipases from species with oil seeds have been widely studied, though their application has turned out to be disappointing, due to low activity and transient expression during seed germination. In the early nineties, research into in non seed tissues showed high lipolytic activity in the latex of some species of Caricaceae, Euphorbiaceae and Asclepiadaceae. At the moment, crude dried latex from Carica papaya is the most studied biocatalyst in lipid synthesis and modification, but little is known about the physiological role of C. papaya lipase or the applications of other latex lipases. In this paper we report more than ten years of research into the characterisation of plant-latex lipases roles and applications
Isoenzimi lipolitici nel latice di alcune specie del genere Euphorbia
No full textNell'ambito di alcuni studi sulle lipasi vegetali è stata accertata la presenza di attività lipolitica in alcuni latici del genere Asclepiadacee, Euforbiacee, Caricacee. In particolare gli studi di caratterizzazione delle lipasi da Carica papaya hanno evidenziato la possibilità di impiego di tali enzimi nelle modificazioni di sostanze grasse e lipidi.
In tale ambito è stata messa in evidenza la presenza di attività lipolitica nei latici di due generi di Euphorbia sotto forma di isoenzimi di cui ne è stata caratterizzata la specificità di substrato e l'attività lipolitica ed esterasica in diverse condizioni sperimentali. Sono stati inoltre messi a punto protocolli estrattivi e purificativi in fase acquosa delle lipasi da latice che potrebbero fornire le condizioni ottimali per una migliore caratterizzazione biochimica degli enzimi stessi
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
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