Littérature scientifique sur le sujet « Sequenza-funzione »

Abstract In base a recenti analisi dei sigilli in pietra iscritti nel sistema di scrittura geroglifico cretese, ancora indecifrato, si puo proporre una nuova ipotesi di interpretazione della funzione di alcuni segni. Alcuni elementi che erano stati considerati come simboli decorativi sono stati re-interpretati, invece, come elementi semantici del repertorio geroglifico cretese. Nel valutare l’attendibilita di questa ipotesi a livello sistemico, proponiamo di attribuire ad alcuni segni del repertorio una funzione logografica, sottolineata dall’uso di filler decorativi che sembrano isolarne la posizione all’interno di una sequenza di sillabogrammi. Come esempio sotteso a questa metodologia, si e rivelata istruttiva una computazione statistica delle attestazioni del segno 044 i soprattutto per gli esempi integrati nelle sequenze ripetute fino ad oggi interpretate come ‘formule’. Alla luce di queste considerazioni, offriamo una nuova interpretazione dell’iconografia di questo segno. Dagli inizi degli studi sul geroglifico, il segno 044 i e stato associato alla rappresentazione di una ‘cazzuola’ (‘trowel’). Qui invece dimostriamo come sia piu plausibile e coerente associarlo alla raffigurazione del cosiddetto Petschaft, una forma funzionale e sofisticata di sigillo a una faccia, utilizzata in un periodo in cui il sistema amministrativo era basato sulla rendicontazione delle attivita attraverso l’uso di sigilli impressi su cretule d’argilla.

La metodica di risonanza magnetica funzionale (fMRI) permette di esplorare le funzioni cognitive in vivo sull'uomo in modo non invasivo. In questo studio presentiamo i primi risultati di un progetto volto alla localizzazione delle aree cerebrali del linguaggio a scopo clinico per la valutazione prechirurgica e per il controllo riabilitativo di pazienti cerebrolesi. Sono stati studiati 10 soggetti sani destrimani e un paziente cerebroleso sinistro. È stata valutata la differenza di segnale di risonanza registrato con sequenza ecoplanare gradient-echo sensibile al segnale T2* comparando volumi cerebrali acquisiti in blocchi di 30 secondi. I soggetti eseguivano alternativamente un compito di decisione lessicale o un compito di decisione grafemica. I risultati dei dati ottenuti dai pazienti di controllo indicano una elevata sensibilità del test mettendo in evidenza tutte le aree note coinvolte nelle funzione linguistiche. L'analisi dei dati ottenuti dal paziente cerebroleso suggeriscono che il protocollo di studio descritto può essere applicato con successo allo studio delle funzioni linguistiche anche in presenza di danno cerebrale.

Questo studio č basato su una tecnica psicodinamica, l'asse della matrice mosaica (MMA), che si pone l'obiettivo di promuovere il consolidamento del Sé soggettivo individuale. Questo processo č permesso da una specifica sequenza psicodinamica: lo stabilirsi della repressione primaria individuale, della differenziazione tra sé e non sé e del vincolo dinamico tra Ego e autoidentitŕ. Un caso di intervento su una classe ingestibile di bambini in etŕ di latenza serve per illustrare la tecnica. L'autore ha condotto la supervisione di una consulente al quarto anno di un master di psicologia clinica. Le fasi dinamiche che hanno permesso il superamento della crisi sono state: 1) mostrando la propria "presenza" ai bambini, l'adulto cattura la libido nel corpo-Ego-identitŕ di ciascun bambino; 2) catturando sia la libido sia l'aggressivitŕ del bambino, l'adulto rafforza la funzione dell'Ego del bambino nel dialogo; 3) creando una configurazione edipica intergenerazionale, che viene rappresentata dal gruppo normativo, l'adulto consente la collocazione del bambino nella configurazione. La strategia di base č stata formulata sulla base della Teoria della fluttuazione dell'equilibrio (Kotani) e si propone la gestione della fluttuazione di ogni bambino come una molecola utile a governare la macro-fluttuazione di una scuola, come organizzazione e come gruppo allargato.

Abstrakt Nelle grammatiche, alla punteggiatura italiana contemporanea di registro medio-alto viene caratteristicamente attribuito un fondamento sintattico e/o prosodico. L’obiettivo di questo intervento consiste nel mostrare che né l’uno né l’altro punto di vista sono adeguati. La funzione della punteggiatura italiana è oggi comunicativa: consiste nel contribuire a definire il contenuto semantico-pragmatico del testo e la sua architettura (le sue diverse unità e le loro connessioni). Questa ipotesi sarà illustrata dapprima ragionando sulla virgola – di cui mi sono già occupata in altre sedi – e poi – con osservazioni del tutto nuove – sul punto e virgola. Riguardo a quest’ultimo, mostrerò come esso sia utilizzato da una parte per articolare l’Enunciato in una sequenza di Unità Informative nucleari collocate sullo stesso piano gerarchico; e dall’altra per accorpare Enunciati semanticamente correlativi o per aggiungere al cotesto un Enunciato con portata logico-tematica locale. Podstawy komunikacyjne interpunkcji włoskiej: przypadek przecinka i średnika Według gramatyk współczesna interpunkcja włoska w rejestrze średnio-wysokim opiera się na składni i/lub prozodii. Celem tego artykułu jest wykazanie, że ani jeden, ani drugi punkt widzenia nie jest właściwy. Funkcja włoskiej interpunkcji jest obecnie komunikatywna: przyczynia się do określenia treści semantyczno-pragmatycznej tekstu oraz jego architektury (rozumianej jako różne jego części i ich związki). Ta hipoteza zostanie najpierw zilustrowana rozważaniami na temat przecinka – którym się zajmowałam już w innych miejscach – a następnie – przedstawiając całkiem nowe spostrzeżenia – na temat średnika. Odnośnie tego ostatniego wykażę, w jaki sposób jest on używany z jednej strony by rozczłonkować Wypowiedź na szereg Jednostek Informacyjnych jądrowych znajdujących się w hierarchii na tym samym poziomie, a z drugiej by połączyć Wypowiedzi semantycznie skorelowane lub by dołączyć Wypowiedź o lokalnym zasięgu logiczno-tematycznym.

Biodiversity of organisms and their genomic content is a valuable source of enzymes, some of which can be isolated and turned into biocatalysts, useful for more sustainable and efficient industrial processes. Organisms thriving in constantly cold environments produce enzymes that may be more efficient in the cold and more thermolabile than enzymes from other organisms, and that display interesting features for the catalysis of several processes that require or are better at low temperature. In the first part of this thesis, two glycoside hydrolases of family 19 (GH19), named LYS177 and LYS188, were identified in the genome of an Antarctic Pseudomonas strain and characterized. Even though most of the characterized GH19 are chitinases, LYS177 and LYS188 showed no chitinolytic activity, but were active as lysozymes with an optimum temperature of 25-35°C, and retained 40% of their highest activity at 5°C. The temperatures of midpoint unfolding transition were estimated to be 20°C higher than their optimum of activity. Based on these features and sequence analysis, LYS177 and LYS188 can be considered cold-active phage endolysins integrated in prophagic regions of the bacterial host. Moreover, the best performing of the two, LYS177, was active and structurally stable over several days only at 4°C, indicating it as a candidate for potential application on the preservation of food and beverages during cold storage. In protein families, enzymes can rapidly acquire new specializations. Therefore, best practices should be implemented to select optimal candidates with the activity of interest and new, potentially promising, features. Characterized GH19 enzymes showed an enhanced in vivo crop defence against chitin containing pathogens and antimicrobial potentialities. In the second part of this thesis, the sequence space of the GH19 family was explored and a database was created to highlight non-described sequences potentially endowed with interesting variants. Based on global pairwise sequence identity of all proteins available in public databases, GH19s were assigned to two subfamilies, the chitinases and the endolysins. Subfamilies were further split into homologous families, which differ in the n° of characterized enzymes they harbour, in the taxonomical distribution, in the presence of accessory domains and loop insertions. Despite this heterogeneity, a core consisting of 27 amino acids around the active site, including important substrate binding residues, was inferred to be conserved between GH19 subfamilies. Thus, this shared core is suggested to be associated to the GH19 capacity to bind sugars containing N-acetyl-glucosamine. Moreover, specifically conserved positions in each subfamily alignment were identified to be a “signature” useful for predicting the substrate specialization of chitinases and endolysins, and to indicate possible outliers with different features. The GH19 evolution was also investigated through molecular phylogeny to explain the observed sequence and structural plasticity: despite endolysins were divided in an higher number of homologous families, they remained in phages and their bacterial hosts, contrary to chitinases, which spread to both prokaryotic and eukaryotic taxa, and acquired at least four loop insertions; moreover, the GH19 chitinase catalytic domain passed from plants to bacteria by horizontal gene transfer in at least two cases. In conclusion, the second part of this thesis shows how bioinformatic tools can be used to analyse the sequence space of a glycoside hydrolase family and extract information to help both experts and non-experts to optimize the discovery of new biocatalysts potentially applied in the field of human health and nutrition.
Biodiversity of organisms and their genomic content is a valuable source of enzymes, some of which can be isolated and turned into biocatalysts, useful for more sustainable and efficient industrial processes. Organisms thriving in constantly cold environments produce enzymes that may be more efficient in the cold and more thermolabile than enzymes from other organisms, and that display interesting features for the catalysis of several processes that require or are better at low temperature. In the first part of this thesis, two glycoside hydrolases of family 19 (GH19), named LYS177 and LYS188, were identified in the genome of an Antarctic Pseudomonas strain and characterized. Even though most of the characterized GH19 are chitinases, LYS177 and LYS188 showed no chitinolytic activity, but were active as lysozymes with an optimum temperature of 25-35°C, and retained 40% of their highest activity at 5°C. The temperatures of midpoint unfolding transition were estimated to be 20°C higher than their optimum of activity. Based on these features and sequence analysis, LYS177 and LYS188 can be considered cold-active phage endolysins integrated in prophagic regions of the bacterial host. Moreover, the best performing of the two, LYS177, was active and structurally stable over several days only at 4°C, indicating it as a candidate for potential application on the preservation of food and beverages during cold storage. In protein families, enzymes can rapidly acquire new specializations. Therefore, best practices should be implemented to select optimal candidates with the activity of interest and new, potentially promising, features. Characterized GH19 enzymes showed an enhanced in vivo crop defence against chitin containing pathogens and antimicrobial potentialities. In the second part of this thesis, the sequence space of the GH19 family was explored and a database was created to highlight non-described sequences potentially endowed with interesting variants. Based on global pairwise sequence identity of all proteins available in public databases, GH19s were assigned to two subfamilies, the chitinases and the endolysins. Subfamilies were further split into homologous families, which differ in the n° of characterized enzymes they harbour, in the taxonomical distribution, in the presence of accessory domains and loop insertions. Despite this heterogeneity, a core consisting of 27 amino acids around the active site, including important substrate binding residues, was inferred to be conserved between GH19 subfamilies. Thus, this shared core is suggested to be associated to the GH19 capacity to bind sugars containing N-acetyl-glucosamine. Moreover, specifically conserved positions in each subfamily alignment were identified to be a “signature” useful for predicting the substrate specialization of chitinases and endolysins, and to indicate possible outliers with different features. The GH19 evolution was also investigated through molecular phylogeny to explain the observed sequence and structural plasticity: despite endolysins were divided in an higher number of homologous families, they remained in phages and their bacterial hosts, contrary to chitinases, which spread to both prokaryotic and eukaryotic taxa, and acquired at least four loop insertions; moreover, the GH19 chitinase catalytic domain passed from plants to bacteria by horizontal gene transfer in at least two cases. In conclusion, the second part of this thesis shows how bioinformatic tools can be used to analyse the sequence space of a glycoside hydrolase family and extract information to help both experts and non-experts to optimize the discovery of new biocatalysts potentially applied in the field of human health and nutrition.