1,720,976 research outputs found
Soil humic molecules affect transport properties of tonoplast vesicles isolated from oat roots
No full textThe effect of a low molecular size (< 5 KDa) humic fraction, essentially fulvic acids, on microsomal and tonoplast ion-stimulated ATPase activity was studied. After 20 min of pre-incubation with microsomal vesicles from oat roots, humic substances at organic C concentration of up to 0.5-mu-g cm-3 increased KCl-stimulated ATPase activity, while they inhibited enzyme activity at higher concentrations. Cl--stimulated ATPase activity of tightly sealed tonoplast-enriched vesicles was similarly affected by < 5 KDa humic substances. This behaviour was not observed when gramicidin D was added to the assay medium. Proton transport by vesicles incubated up to 5 min with < 5 KDa humic molecules was affected in a concentration-dependent manner, strongly resembling that observed for ATP hydrolysis, whereas it was severely reduced when the assay conditions were close to those used for measuring ATP hydrolysis (20 min pre-incubation of vesicles with humic substances). The transmembrane electrical potential was negatively affected, irrespective of the concentration of humic molecules. Furthermore, a 15-min pre-incubation strongly reduced the formation of a potential gradient. The size and concentrations of humic substances employed make an interaction with the vacuolar membrane of root cells plausible. The results show that the main target of humic molecules is the electrical membrane potential and suggest a possible way of interference of these naturally occurring substances with the biochemical mechanisms involved in plant mineral nutrition
Effect of ABA on crop load control and fruit quality improvement in ‘Gala’ apple
No full textAn ABA formulation was applied on ‘Gala Schniga’ apple cultivar to evaluate its efficacy as a thinning agent and as an alternative treatment for preventing Ca2+related disorders, such as bitter pit, in apple. ABA was tested in a single (19 days after full bloom, dafb) or in three-repeated application (19, 29 and 39 dafb). ABA increased fruit abscission either when sprayed in a single or multiple treatments. Yield and average fruit weight of the ABA treated trees were similar to the values reached in the hand-thinned trees, and fruits were induced to ripen slightly earlier than the control ones. In controlled conditions, spraying of fruits with ABA at three different stages of growth (62, 78 and 112 dafb) showed to positively affect the uptake of the Ca2+ and other minerals which levels are normally associated with the appearance of bitter pit in fruits
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
IAA levels in Prunus persica (L.) Batsch in relation to fruit growth and development
No full textLevels of IAA, determined by spectrofluorimetry were assessed during different phases of fruit growth and development. Hormone concentration was related to growth rate expressed in terms of diameter, seed length and seed dry weight (DW). Proteins in the seed were also determined. Results showed that high levels of IAA precede the two phases of high growth rate (SI and SIII). The same relationship exists between IAA concentration and dry weight and protein content of the seed
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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