1,721,279 research outputs found
Quenching of chlorophyll triplet states by carotenoids in reconstituted Lhca4 subunit of peripheral light-harvesting complex of photosystem I
No full textIn this study, triplet quenching, the major photoprotection mechanism in antenna proteins, has been studied in the light-harvesting complex of photosystem I (LHC-I). The ability of carotenoids bound to LHC-I subunit Lhca4, which is characterized by the presence of the red-most absorption components at wavelength >700 nm, to protect the system through quenching of the chlorophyll triplet states, has been probed, by analyzing the induction of carotenoid triplet formation. We have investigated this process at low temperature, when the funneling of the excitation toward the low-lying excited states of the Chls is stronger, by means of optically detected magnetic resonance (ODMR), which is well-suited for investigation of triplet states in photosynthetic systems. The high selectivity and sensitivity of the technique has made it possible to point out the presence of specific interactions between carotenoids forming the triplet states and specific chlorophylls characterized by red-shifted absorption, by detection of the microwave-induced Triplet minus Singlet (T-S) spectra. The effect of the red forms on the efficiency of triplet quenching was specifically probed by using the Asn47His mutant, in which the red forms have been selectively abolished (Morosinotto, T., Breton, J., Bassi, R., and Croce, R. (2003) J. Biol. Chem. 278, 49223-49229). Lack of the red forms yields into a reduced efficiency of the triplet quenching in LHC-I thus suggesting that the "red Chls" play a role in enhancing triplet quenching in LHC-I and, possibly, in the whole photosystem I
Commento ai Dialoghi filosofici di Antonio Conti, in Antonio Conti, Dialoghi filosofici. Edizione critica e commento di Romana Bassi e Renzo Rabboni, MEMORIE - ISTITUTO VENETO DI SCIENZE, LETTERE ED ARTI. CLASSE DI SCIENZE MORALI, LETTERE ED ARTI
No full textThe antenna system of higher plants Photosystem I and its interactions with the core complex
No full textOrpheus and 'second nature' in Francis Bacon
Full text linkWhile Francis Bacon’s interpretations of mythological figures such as those of Prometheus, Proteus and Vulcan have received quite a bit of attention by scholars, the myth of Orpheus shows a wealth of meanings almost entirely still to be explored. In particular we argue that Aristotle’s ethical notion of “second nature” plays a role in how Bacon frames this myth. By parallel reading De Augmentis scientiarum, I, 41 and De Sapientia Veterum, 11, it becomes evident that Bacon 1) extends to animals the notion of “altera natura”, by 2) showing the civilizing effects of order and harmony and 3) assigns to moral and civil philosophy the political function of letting men’s second nature emerge as an attitude to be pacific and social. In doing so he 4) subscribes to a cyclical view of the motion of history, menaced by the recurring falls in barbarian times. Harmony set by philosophy seems therefore to possess a binding power (vinculum) that is both fragile, compelling and liberating: the underlying concept of “nature bound” helps explaining why in Orpheus’ principle of harmony Bacon can trace the activity of both natural and moral philosophy
A CK2 site is reversibly phosphorylated in the photosystem II subunit CP29
No full textProtein phosphorylation is a major mechanism in the regulation of protein function. In chloroplast thylakoids several photosystem II subunits, including the major antenna light-harvesting complex II and several core complex components, are reversibly phosphorylated depending on the redox state of the electron carriers. A previously unknown reversible phosphorylation event has recently been described on the CP29 subunit which leads to conformational changes and protection from cold stress (Bergantino, E., Dainese, P., Cerovic, Z. Sechi, S. and Bassi, R. (1995) J. Biol Chem. 270, 8474-8481). In this study, we have identified the phosphorylation site on the N-terminal, stroma-exposed domain, showing that it is located in a sequence not homologous to the other members of the Lhc family. The phosphorylated sequence is unique in chloroplast membranes since it meets the requirements for CK2 (casein kinase II) kinases. The possibility that this phosphorylation is involved in a signal transduction pathway is discusse
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
Retraction Note: Increased biomass productivity in green algae by tuning non-photochemical quenching (Scientific Reports, (2016), 6, 1, (21339), 10.1038/srep21339)
No full textNon-Photochemical quenching does not control producivity in Chlamydomonal reinhardtii in contrast to previous reports
- …
