1,721,526 research outputs found
The Chemistry of Olive Oil: an endless story
Full text linkBecause of their value, Olive oils, undergo to several attempts of adulteration and this improved the performances of analytical methods developed to check their authenticity. After the eve of the “Chemistry of indexes”, the development of separation techniques greatly improved the knowledge of the composition of lipids; the earlier gas chromatographic separations of fatty acid, could last even more than 40 minutes and the evaluation of minor fatty acids were problematic, at Bologna University, their previous separation on silver nitrate silica gel TLC was applied in 1974–1975, in order to concentrate them and obtain a better chromatogram. The gas chromatographic evaluation of minor compounds was another interesting challenge, packed columns with apolar stationary phase, admit the separation of few peaks; in 1975, the use of a slightly more polar stationary phase (OV17) highlighted the presence of Δ-5-avenasterol in olive oils. 1981 is a milestone for olive oil analytical control: Regulation (CEE) 2568/91 made the use of capillary columns mandatory. Official analytical methods consider many parameters, enclosed sensory evaluation, that is not matter for chemists, however, chemists are moved by curiosity and several papers had been published on the relationship between the volatile compounds of head space of olive oil and sensory characteristics. Despite being one of the more studied food, olive oils’ composition continues to give the chemists the possibility to discover new compounds, e.g. degradation products of sterols that leads to the standardization of the method for sterenes evaluation. From 1973 to nowadays, the laboratory performances greatly improved, nowadays it is possible to generate a huge number of data in a short time, then the problem is how to correctly interpretate them, surely chemometric and lipidomic greatly can help
Storage globulins in Gnetopsida. 1. Recognition of legumin-iike proteins
No full textSalt soluble storage proteins were extracted from seeds of Ephedra distachya, Ephedra foeminea, Gnetum gnemon, Gnetum montanum and Welwitschia mirabilis and separated by chromatographic procedures. The molecular weight of the main storage globulin ranges from 300 to 350 kD. Danaturation by SDS resolved the holoprotein in monomers of Mr 40 to 60 kD. Oligomers up to 120 kD were observed in Ephedra. Reduction of disulphide bridges by DTE resolved the monomers in paris of polypeptides of Mr 10 to 35 kD. The characters above indicate that the main storage globulin of Gnetopsida is a legumin-like protein
Storage globulins in Gnetopsida.2. A serotaxonomic study of legumin-like proteins
No full textLegumin-like proteins from Ephedra distachya, Ephedra foem’tnea, Gnetum gnemon, Gnetum montanum, and Welwitschia mirabilis and four Angiosperms (Magnolia grandiflora, Pisum sativum, Glycine max, and Cucurbita moschata) were used in a serological investigation. The immunological tests demonstrate the heterogeneity of Gnetopsida and indicate discriminative correlations of Welwitschia, Gnetum and Ephedra to the examined Angiosperms
Congruenza e discordanza fra sierotassonomia, tassonomia numerica e tassonomia tradizionale nelle Leguminosae
No full textA comparison among 37 specimens representative of Swartzieae, Sophoreae, Tephorosieae, Indigofereae, Psoraleeae, Desmodieae and Phaseoleae has been performed on the ground of biochemical and morphological characters. In particular the serological cross reactions of the seed proteins were tested by immunodiffusion, and more than one hundred characters were surveyed about vegetative and reproductive features. The two distinct sets of data have been processed by cluster analysis and two different sets of phenetical groupings have been obtained, which also differ from the groups of traditional taxonomy. Since the naturalness of the tribes considered is not something undoubtable, the pointed out incongruences may be due to areai lack of homogeneity in these traditional taxa
La Cassa di Risparmio della Provincia dell’Aquila. Risparmio, ceti dirigenti, sviluppo economico, 1859-2009
No full textIl volume ripercorre le fasi della fondazione e sviluppo di un medio istituto di credito nel contesto dell'Italia post-unitaria, con particolare riferimento ai rapporti con la crescita dell'area della regione Abruzzo, nel periodo 1861-1950..The book deals with the foundation and development of an average bank in Italy after the unification in deep connection with the history of the growth of the region Abruzzo untill 1950
Botanica sistematica Un approccio filogenetico
No full textLa quarta edizione di "Botanica sistematica: un approccio filogenetico" esce a 8 anni dalla terza, nell'intento di riportare i progressi compiuti in questa disciplina.
"Le nostre classificazioni diventeranno, per quanto possibile, genealogie" affermava Darwin nel saggio sulle specie del 1859 e così è stato: la sistematica biologica, alla luce di un'impostazione evoluzionistica, e superando la staticità di una "scala naturae" di aristotelica memoria, si è sviluppata privilegiando una visione dinamica della diversità degli organismi viventi, cioè la concezione di un'evoluzione non più lineare, ma ramificata, che ha portato alla "consacrazione dell'albero quale immagine della natura", come Giulio Barsanti scrive in "Una lunga pazienza cieca. Storia dell'evoluzionismo".
Questo volume si concentra sulla porzione del complesso albero della vita in cui si collocano le piante; focalizzandosi in particolare sulle piante a fiore, gli autori ne delineano le relazioni filogenetiche, riportandole in una classificazione che rifletta il possibile svolgimento della storia evolutiva degli organismi vegetali.
Basata tradizionalmente su caratteri morfologici, la botanica sistematica nel tempo ha utilizzato informazioni provenienti da diverse fonti, purché in grado di evidenziare differenze e affinità entro e tra taxa; la classificazione proposta in questo volume è il risultato di analisi comparate di dati non solo morfologici, ma anche biochimici, ultrastrutturali, cariologici, molecolari. Questi ultimi, derivati soprattutto da sequenze nucleotidiche del DNA, si sono aggiunti negli ultimi decenni, permettendo di integrare approcci diversi.
Gli alberi filogenetici che vengono proposti sono modellati sui principi rigorosi della cladistica; di conseguenza, da un punto di vista nomenclaturale, ricevono un riconoscimento tassonomico soltanto i gruppi che risultano strettamente monofiletici.
Questo significa abbandonare, com'è noto, raggruppamenti tramandati dalla tradizione, come la confortevole dicotomia monocotiledoni/dicotiledoni, giunta fino a noi dai botanici inglesi del 17° secolo, e adeguarsi a raggruppamenti relativamente nuovi (i.e., il clade delle Streptofite, o quello delle Eufillofite) o nuovissimi (i.e., il clade SARP, che trascrivo come sigla, non avendo trovato una traduzione adeguata per "Diaphoretickes").
Quanto ciò possa agevolare la comunicazione tra esperti, o addirittura tra non esperti, che pure dovrebbe essere uno degli scopi della sistematica, è inutile dire. Per contro non si può dubitare sulla validità del metodo oggettivo e riproducibile, e quindi scientifico, adottato dalla cladistica nell'indagare il rapporto causa-effetto tra evoluzione e filogenesi.
Lucia Cont
Phylogenetic patterns and endemism genesis in Cytisus desf. (Leguminosae-Cytiseae) and related genera
No full textA cladistic analysis based on morphological characters was performed on Cytisus and related genera. Terminal taxa were three Mediterranean endemics (C. aeolicus, C. emeriflorus, and C. tribracteolatus), all sections of genus Cytisus, and all other genera of the tribe. The main dichotomy within the tribe, between Cytisus group and Genista group, is corroborated. Both genera, Genista and Cytisus, seem to be paraphyletic. Cytisus s.s. is composed of at least three clades. The cladograms indicate a link of C. emeriflorus with sect. Tubocytisus, and of C. aeolicus with C. villosus. C. tribracteolatus belongs to the same clade as the two species above, but is more loosely related to them. The phyletic relations suggested are compatible with phytogeography. On the basis of this analysis, an evolutionary sketch is outlined and some taxonomic realignments are proposed. © 2002 Taylor & Francis Group, LLC
Assessment of RAPD variation in Abies nebrodensis (Lojac.) Mattei (Pinaceae) using haploid tissue analysis
No full textRAPD technique using haploid DNA from megagametophyte tissue was applied to detect the pattern of genetic variation within Abies nebrodensis, a species endemic to Sicily. Results were compared with a reference system composed of representatives of five Mediterranean firs: A. alba, A. cephalonica, A. nordmanniana, A. numidica, and A. pinsapo. Diploid genotypes for RAPD loci were inferred from segregation patterns in haploid megagametophytes from individual trees. Therefore, it was possible to distinguish between homo- and heterozygotes carrying a RAPD fragment and to calculate unbiased estimates of genetic parameters. In the interspecific comparison, A. nebrodensis appears intermixed with the other Abies species, supporting the hypothesis of remarkable hybridization processes within the genus. A high level of polymorphism and deviation from panmictic equilibrium as a result of heterozygote excess depict a pattern of population structure in A. nebrodensis that agrees with the expectations for an outcrossing perennial species, in spite of its critical conditions. Implications with respect to the conservation management of the species are also discussed
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