172,581 research outputs found
Lysyl oxidase activity and elastin/glycosaminoglycan interactions in growing chick and rat aortas
No full textHydrophobic tropoelastin molecules aggregate in vitro in physiological conditions and form fibers very similar to natural ones (Bressan, G.M., I. Pasquali Ronchetti, C. Fornieri, F. Mattioli, I. Castellani, and D. Volpin, 1986, J. Ultrastruct. Molec. Struct. Res., 94:209-216). Similar hydrophobic interactions might be operative in in vivo fibrogenesis. Data are presented suggesting that matrix glycosaminoglycans (GAGs) prevent spontaneous tropoelastin aggregation in vivo, at least up to the deamination of lysine residues on tropoelastin by matrix lysyl oxidase. Lysyl oxidase inhibitors beta-aminopropionitrile, aminoacetonitrile, semicarbazide, and isonicotinic acid hydrazide were given to newborn rats, and the ultrastructural alterations of the aortic elastic fibers were analyzed and compared with the exent of the enzyme inhibition. When inhibition was >65% all chemicals induced alterations of elastic fibers in the form of lateral aggregates of elastin, which were always permeated by cytochemically and immunologically recognizable GAGs. The number and size of the abnormal elastin/GAGs aggregates were proportional to the extent of lysyl oxidase inhibition. The phenomenon was independent of the animal species. All data suggest that, upon inhibition of lysyl oxidase, matrix GAGs remain among elastin molecules during fibrogenesis by binding to positively charged amino groups on elastin. Newly synthesized and secreted tropoelastin has the highest number of free epsilon amino groups, and, therefore, the highest capability of binding to GAGs. These polyanions, by virtue of their great hydration and dispersing power, could prevent random spontaneous aggregation of hydrophobic tropoelastin in the extracellular space
Elastin fiber-associated glycosaminoglycans in beta-aminopropionitrile-induced lathyrism.
No full textRuthenium red and toluidine blue O precipitates were described associated with lathyritic elastic fibers in aortas of chickens treated with beta-aminopropionitrile fumarate (I. Pasquali-Ronchetti, C. Fornieri, I. Castellani, G. M. Bressan, and D. Volpin (1981). Alterations of the connective tissue components induced by beta-aminopropionitrile. Exp. Mol. Pathol. 35, 42-56). In this report evidence is given that these precipitates reveal the presence of proteoglycans, as they are completely removed by 5 M guanidine-HCl incubation and by specific enzymatic digestions. In particular, proteoglycans associated with the poorly cross-linked lathyritic elastin can be removed by testicular hyaluronidase, chondroitinase ABC, heparitinase, and nitrous acid treatments, whereas they are rather resistant to streptococcal hyaluronidase and chondroitinase AC. On the contrary, proteoglycans of the matrix or associated with collagen fibers are particularly sensitive to these latter enzymatic treatments. The conclusion is reached that glycosaminoglycans associated with beta-aminopropionitrile-induced lathyritic elastin (i) are different from those of the matrix or associated with collagen, and (ii) include mainly dermatan and heparan sulfates
A sting affair : a global quantitative exploration of bee, wasp and ant hosts of velvet ants
No full textThe vast majority of species of velvet ants (Hymenoptera: Aculeata: Mutillidae) are ectoparasitoids of immature stages of other aculeate Hymenoptera (bees, wasps and ants). Due to their cryptic, furtive behaviour at the host nesting sites, however, even basic information on their biology, like host use diversity, is still unknown for entire subfamilies, and the known information, scattered in over two centuries of published studies, is potentially hiding tendencies to host specialization across velvet ant lineages. In this review, based on 305 host associations spanning 132 species in 49 genera and 10 main lineages (tribes/subfamilies), we explored patterns of host use in velvet ants. Overall, 15 families and 29 subfamilies of Aculeata are listed as hosts of mutillids, with a strong predominance of Apoidea (bees and apoid wasps: 19 subfamilies and 82.3% of host records). A series of bipartite networks, multivariate analyses and calculations of different indices suggested possible patterns of specialization. Host taxonomic spectrum (number of subfamilies) of velvet ants was very variable and explained by variation in the number of host records. Instead, we found a great variation of network-based host specialization degree and host taxonomic distinctness that did not depend on the number of host records. Differences in host use patterns seemed apparent across mutillid tribes/subfamilies, among genera within several tribes/subfamilies, and to lesser extent within genera. Taxonomic host use variation seemed not dependent on phylogeny. Instead, it was likely driven by the exploitation of hosts with different ecological traits (nest type, larval diet and sociality). Thus, taxonomically more generalist lineages may use hosts that essentially share the same ecological profile. Interestingly, closely related mutillid lineages often show contrasting combinations of host ecological traits, particularly sociality and larval diet, with a more common preference for ground-nesting hosts across most lineages. This review may serve as a basis to test hypotheses for host use evolution in this fascinating family of parasitoids
Occurrence of DNA sequence differences in C-heterochromatin of Eulemur coronatus and Eulemur macaco, as revealed by fluorescence resonance energy transfer.
No full textIn the genus Eulemur (Malagasy lemurs) karyotype diversification has occurred mainly through Robertsonian mechanisms of chromosome fusion (Rumpler et al., 1976). Eulemur coronatus is the sole species to have the largest genome size, due to a very large amount of C-heterochromatin, mostly located at the pericentromeric regions of the largest chromosomes (Warter and Rumpler, 1985). This increase in C-heterochromatin was thought to be due to DNA amplification (Ronchetti et al., 1993). The aim of this work was to investigate whether the large C-heterochromatin of Eulemur coronatus might have derived by amplification of the smaller C-heterochromatin of Eulemur macaco, a closely related species with smaller genome size. To obtain information on the overall base composition of the total genomes, on the relative interspersion of AT and GC base paris along the DNA molecule and on the structural differences in C-heterochromatin, we used a quantitative cyto-chemical approach, based on fluorescence resonance energy transfer (FRET) between DNA-specific fluorochromes (i.e. the AT-specific Hoechst 33258, and the non base-specific dye, propidium iodide). Micro-spectrofluorometry and image analysis were used to investigate both the overall FRET efficiency and its spatial distribution along the chromosome arms. FRET efficiency values of the DNA in C-heterochromatin were significantly different in the two Eulemur species, indicating a different qualitative composition of repetitive DNA. This suggests that the repetitive DNA of Eulemur coronatus cannot have originated by amplification in toto of the repetitive DNA sequences of Eulemur macaco
Stereochemistry of the hydrogen introduction at C-25 in the biosynthesis of tomatidine
No full textThe C-26 atom of tomatidine, bearing the nitrogen atom, derives from the C-2 atom of MVA; from this it is inferred that the introduction of hydrogen at the C-25 atom of the Δ24 biosynthetic intermediate occurs from the 24-si, 25-si face
The Crucial Role of Green Soft Skills and Leadership for Sustainability: A Case Study of an Italian Small and Medium Enterprise Operating in the Food Sector
No full textIncreasing concerns about the human impact on the environment are leading to new
challenges for companies and their employees. Specifically, the food industry is facing the need to
provide sustainable services, requiring a specialized and skilled workforce. This article presents
a case study of an Italian sustainable Small and Medium Enterprise (SME) operating in the food
sector in order to determine the drivers of working for this company, the key skills needed, and the
Green Human Resource Management practices adopted. A total of 13 semi-structured interviews
were conducted with employees and thematically analyzed. The findings showed that soft skills
were perceived as more relevant than hard skills, although the food sector is characterized by high
technical complexity and subjected to several national and international regulations. Moreover, the
crucial role of organizational culture in determining the relevance of soft skills within the company
and in fostering the implementation of the holacracy organizational management method emerged.
Finally, by detecting the relevance recognized to values and soft skills during the recruitment and
selection process, our findings provided some evidence of Green Human Resource Management in
sustainable SMEs
Fate of C-24 hydrogen atoms of cholesterol during its conversion into tigogenin in Digitalis lanata
No full text(24R)-[24-3H]- and (24S)-[24-3H]-cholesterols are transformed into tigogenin [(25R)-5α-spirostan-3β-ol] in Digitalis lanata without involvement of the hydrogen atoms at C-24; this confirms that the reduction of the Δ24-precursor of cholesterol is a ‘trans’ process
Esegesi di un titolo. Velimir Chlebnikov, Zmej poezda.
No full textIl titolo scelto per un’opera letteraria tratteggia i contorni di possibili avvicinamenti al testo. Ciascun titolo riassume e rappresenta il componimento, lasciando aperta una certa dose di ambiguità e qualsiasi riflessione su di esso implica un carattere interpretativo ed ermeneutico. Nel nome possono confluire elementi legati all’autore, riferimenti al mondo esterno nel quale egli si colloca e correlazioni interne al corpo stesso dell’opera. Dare senso a tale nome richiede la conoscenza dell’intero testo, delle sue relazioni con l’autore e la sua produzione.
L’articolo riflette sulle domande che i due vocaboli scelti da Velimir Chlebnikov come titolo per il suo poema Zmej poezda (1910) pongono al lettore e quindi al traduttore. I termini che si associano a comporre il nome del poema, ‘zmej’ (masch. ‘drago’) e ‘poezd’ (masch. ‘treno’), evocano due immagini-concetto ricche di senso e dense di rimandi al pensiero estetico dell’autore e alla tradizione culturale cui egli era esposto, in un gioco di immagini fra drago e serpente, presente nel titolo originale e sviluppato nel testo. Tale sovrapposizione di forme creata dall’autore dovrebbe essere, almeno parzialmente, restituita nel titolo tradotto. Seguendo l’anelito chimerico volto a costruire utopie primordiali, Chlebnikov recupera la tradizione letteraria del mostro di fuoco, congiungendola con un rinnovato slancio, scientifico e artistico, in direzione di una bramata armonia fra passato e futuro, fra natura e tecnica, albero e treno. In questo composito universo figurativo al traduttore spetta il non facile compito di effettuare scelte, interpretare e selezionare il materiale, con l’auspicio di offrire al lettore italiano, ignaro della ricchezza originale, le suggestioni poetiche e il ritmo fonico del poema di Chlebnikov. Si giunge così all’ultimo passaggio, che fissa (temporaneamente) la traduzione italiana del titolo del poema, una sola parola con diversi, possibili sensi.The title chosen for a literary work encloses possible approaches to the text. Each title summarizes and represents the text with a certain degree of ambiguity, and any discussion on it implies an interpretative and hermeneutic process. In the title merge together different elements: references linked to the author or to the outside world in which he is placed, internal link to the text itself and correlations to other literary works. A full comprehension of the title requires an understanding of the entire text, its relationship with the author, with his artistic production and with his epoch. The article analyzes the two words chosen by Velimir Khlebnikov as a title for his poem Zmej poezda (1910), in the perspective of a possible Italian translation
The structure of syriogenin
No full textSyriogenin was demonstrated by chemical and spectroscopic evidence to have the structure 12β-hydroxyuzarigenin and confirmed by transformation into 3,12-diketo-5α,14α-etianic acid methyl ester
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