Gotowa bibliografia na temat „TRNA Participation”

We generated a conditional CCase mutant of Bacillus subtilis to explore the participation in vivo of the tRNA nucleotidyltransferase (CCA transferase or CCase) in the maturation of the single-copy tRNACys, which lacks an encoded CCA 3′ end. We observed that shorter tRNACys species, presumably lacking CCA, only accumulated when the inducible Pspac : cca was introduced into an rnr mutant strain, but not in combination with pnp. We sequenced the tRNA 3′ ends produced in the various mutant tRNACys species to detect maturation and decay intermediates and observed that decay of the tRNACys occurs through the addition of poly(A) or heteropolymeric tails. A few clones corresponding to full-size tRNAs contained either CCA or other C and/or A sequences, suggesting that these are substrates for repair and/or decay. We also observed editing of tRNACys at position 21, which seems to occur preferentially in mature tRNAs. Altogether, our results provide in vivo evidence for the participation of the B. subtilis cca gene product in the maturation of tRNAs lacking CCA. We also suggest that RNase R exoRNase in B. subtilis participates in the quality control of tRNA.

Ribosome biogenesis, a complex multistep process, results in correct folding of rRNAs, incorporation of >50 ribosomal proteins, and their maturation. Deficiencies in ribosome biogenesis may result in varied faults in translation of mRNAs causing cellular toxicities and ribosomopathies in higher organisms. How cells ensure quality control in ribosome biogenesis for the fidelity of its complex function remains unclear. Using Escherichia coli, we show that initiator tRNA (i-tRNA), specifically the evolutionarily conserved three consecutive GC base pairs in its anticodon stem, play a crucial role in ribosome maturation. Deficiencies in cellular contents of i-tRNA confer cold sensitivity and result in accumulation of ribosomes with immature 3′ and 5′ ends of the 16S rRNA. Overexpression of i-tRNA in various strains rescues biogenesis defects. Participation of i-tRNA in the first round of initiation complex formation licenses the final steps of ribosome maturation by signaling RNases to trim the terminal extensions of immature 16S rRNA.

Abstract Type II toxin–antitoxins systems are widespread in prokaryotic genomes. Typically, they comprise two proteins, a toxin, and an antitoxin, encoded by adjacent genes and forming a complex in which the enzymatic activity of the toxin is inhibited. Under stress conditions, the antitoxin is degraded liberating the active toxin. Though thousands of various toxin–antitoxins pairs have been predicted bioinformatically, only a handful has been thoroughly characterized. Here, we describe the AtaT2 toxin from a toxin–antitoxin system from Escherichia coli O157:H7. We show that AtaT2 is the first GNAT (Gcn5-related N-acetyltransferase) toxin that specifically targets charged glycyl tRNA. In vivo, the AtaT2 activity induces ribosome stalling at all four glycyl codons but does not evoke a stringent response. In vitro, AtaT2 acetylates the aminoacyl moiety of isoaccepting glycyl tRNAs, thus precluding their participation in translation. Our study broadens the known target specificity of GNAT toxins beyond the earlier described isoleucine and formyl methionine tRNAs, and suggest that various GNAT toxins may have evolved to specificaly target other if not all individual aminoacyl tRNAs.

In yeast and higher eukaryotes, transcription factor TFIIIB is required for accurate initiation of transcription by RNA Polymerase III (Pol III), which synthesizes transfer RNAs (tRNAs), 5S ribosomal RNA (rRNA), and other essential RNA molecules. TFIIIB is composed of three subunits: B double prime 1 (Bdp1), TATA-binding protein (TBP), and TFIIB-related factor 1 (Brf1). Here, we report the molecular characterization of Brf1 in Leishmania major (LmBrf1), a parasitic protozoan that shows distinctive transcription characteristics, including the apparent absence of Pol III general transcription factors TFIIIA and TFIIIC. Although single-knockout parasites of LmBrf1 were obtained, attempts to generate LmBrf1-null mutants were unsuccessful, which suggests that LmBrf1 is essential in promastigotes of L. major. Notably, Northern blot analyses showed that the half-lives of the messenger RNAs (mRNAs) from LmBrf1 and other components of the Pol III transcription machinery (Bdp1 and Pol III subunit RPC1) are very similar (~40 min). Stabilization of these transcripts was observed in stationary-phase parasites. Chromatin immunoprecipitation (ChIP) experiments showed that LmBrf1 binds to tRNA, small nuclear RNA (snRNA), and 5S rRNA genes. Unexpectedly, the results also indicated that LmBrf1 associates to the promoter region of the 18S rRNA genes and to three Pol II-dependent regions here analyzed. Tandem affinity purification and mass spectrometry analyses allowed the identification of a putative TFIIIC subunit. Moreover, several proteins involved in transcription by all three RNA polymerases co-purified with the tagged version of LmBrf1.

ABSTRACT To better characterize the mechanisms responsible for RNA export from the nucleus, we developed an in vitro assay based on the use of permeabilized HeLa cells. This new assay supports nuclear export of U1 snRNA, tRNA, and mRNA in an energy- and Xenopusextract-dependent manner. U1 snRNA export requires a 5′ monomethylated cap structure, the nuclear export signal receptor CRM1, and the small GTPase Ran. In contrast, mRNA export does not require the participation of CRM1. We show here that NXT1, an NTF2-related protein that binds directly to RanGTP, strongly stimulates export of U1 snRNA, tRNA, and mRNA. The ability of NXT1 to promote export is dependent on its capacity to bind RanGTP. These results support the emerging view that NXT1 is a general export factor, functioning on both CRM1-dependent and CRM1-independent pathways of RNA export.

Kae1 is a subunit of the highly evolutionarily conserved KEOPS/EKC complex, which is involved in universal (t6A37) tRNA modification. Several reports have discussed the participation of this complex in transcription regulation in yeast and human cells, including our previous observations of KaeA, an Aspergillus nidulans homologue of Kae1p. The aim of this project was to confirm the role of KaeA in transcription, employing high-throughput transcriptomic (RNA-Seq and ChIP-Seq) and proteomic (LC-MS) analysis. We confirmed that KaeA is a subunit of the KEOPS complex in A. nidulans. An analysis of kaeA19 and kaeA25 mutants showed that, although the (t6A37) tRNA modification is unaffected in both mutants, they reveal significantly altered transcriptomes compared to the wild type. The finding that KaeA is localized in chromatin and identifying its protein partners allows us to postulate an additional nuclear function for the protein. Our data shed light on the universal bi-functional role of this factor and proves that the activity of this protein is not limited to tRNA modification in cytoplasm, but also affects the transcriptional activity of a number of nuclear genes. Data are available via the NCBI’s GEO database under identifiers GSE206830 (RNA-Seq) and GSE206874 (ChIP-Seq), and via ProteomeXchange with identifier PXD034554 (proteomic).

In this modern global society, where egocentric attitudes lead to the individual feeling fragmented, alone, and ever more competitive, and where educational and social institutions are ever more strained (the well-known “crisis in education, the family, and other institutions”), it becomes of paramount importance, firstly, to comprehend such dynamics, and, secondly, to cooperate in order to create and build a socio-political and pedagogic path towards global change, with the aim of overcoming the social isolation and devaluation of the individual, reconstructing a network of relationships and community interactions and ever more active means of participation by all those involved. The present research starts from the above point of view. On the one hand, information is presented about the cultural and organizational dimensions of current day schooling and the relationship between the school and the local community, and an alternative model of “socioeducational culture” is proposed, based around individuals in a local socio-cultural context. More specifically, using a mainly ethnographic ideology, a study is undertaken of four primary schools in three different types of neighbourhood (2 in the province of Treviso, 1 in Salvador de Bahia, Brazil, and 1 in Bogota, Colombia) and their relative local contexts (mainly represented by family and external socio-educational organizations). On the other hand, using observations which emerge from analysis of the data, and by comparing the existing scientific literature, the research aims to define a proposed model for an all-inclusive, community-based, state school, both integral to, and integrated in, the local community, within an integrated local education system which in turn is both participatory and community-based (the pedagogic purpose). The main findings emerging from the field research were analysed at two levels of interpretation, the level of interpersonal relationships, and the degree of participation in democratic management. Results showed: how meetings (both formal and informal) were structured; a representation of their educational role; a picture of both interpersonal and interinstitutional relationships at the local internal level; and a view of local participation, of both adults and children, and its role. Following initial analysis and reconstruction of the local cultural framework specific to each observed context, the second part of the research comprised an intercultural comparison of the main findings – both frequently recurring and unusual findings. For example, in all four contexts, despite different characteristics, it emerged that the “community relations” dimension is closely linked to that of “participatory management”, and that in the socioeducational organization equal paths are pursued in the exploitation of relationships, the humanization of relationships and of conflict management on the one hand, and on the other, of raising awareness, the promotion of a social option (Don Milani’s “I care”) and a framework of appropriate space for the democratic participation of the different individuals involved – adults and children –space where, by comparison and negotiation of “culture” (meaning, expectations, values), a critical understanding of reality can be triggered, and shared planning of improved ways towards greater humanisation implemented. The present cross-sectional analysis leads to a vision of the school and local community understood as places to be lived in a new way, being actively participated in, and experienced as a community of inter-related individuals involved in a mutual process of educational and social improvement. An interpretative analysis and critical reflection of the pedagogic option adopted, within a framework of school autonomy and a widespread demand for more local self-determination, can be related to authors such as Dewey, Mounier, Freinet, Freire and Milani. These, among others, shared a transformational, liberating and democratic vision they thought important to recover, both in the school and in the local and wider community, to create foundations for the genuine development of the whole human being, integral to, and integrated in, the local community. The vision is one of a school, able to discover its own social and political role, and critically confront, even welcome, external requests for a higher quality teaching framework, within a comprehensive and integrated programme of education, whilst respecting the areas of competence of individuals. The vision is one of a localised social and educational system, able to renegotiate its own cultural foundations, adopting a shared perspective on which to build the local “educational community”, leading to the prospect of an “educational city” (Barcellona, 1990).

Negli ultimi decenni del XX secolo molti stati arabi hanno dovuto fare i conti con l intensificarsi della coscienza etnica e religiosa, che ha generato spesso conflitti interni e instabilità politica e sociale. Tutte le società composte da diverse comunità hanno sperimentato, nel corso del tempo, tensioni e conflitti, sebbene le identità religiose ed etniche non siano sempre state esattamente fissate e delineate da contorni netti, diventando oggetto di rinegoziazione e ridefinizione ed assumendo un ruolo minoritario o maggioritario. In stati come l Egitto ove, accanto alla maggioranza musulmana, è presente una consistente comunità cristiana, la riflessione politica e sociale si è soffermata spesso su temi riguardanti la pubblica cittadinanza, la società civile e la partecipazione politica, al fine di comprendere quale sia il ruolo riservato alle comunità di religione non musulmana all interno della struttura sociale e del quadro politico statuale. Il lavoro qui presentato cerca di comprendere in quale misura i cambiamenti avvenuti nell Egitto contemporaneo abbiano influenzato il processo di definizione dell identità nazionale e i rapporti politici, sociali ed economici tra la comunità copta e la leadership al potere, con una riconsiderazione della posizione assunta dai copti all interno della società egiziana. L obiettivo che ci siamo proposti è quello di esaminare il ruolo svolto dalla comunità copta nell ambito politico e sociale e nelle relazioni con il governo all interno del quadro storico dell Egitto nasseriano; in quest analisi uno sguardo privilegiato assumono le dinamiche interne alla comunità copta che provocano l emergere di nuovi protagonisti, influenzandone le relazioni con il potere. Gamal Abd al-Nasser, leader del movimento e presidente della Repubblica egiziana dal 1956, si fece portavoce di un programma politico che segnò una definitiva cesura, non solo dal punto di vista istituzionale, con il regime liberale precedente. Mettendo al centro dell attenzione la problematica sociale e quella nazionale, il ra is cercò di ridurre i conflitti di natura confessionale. Nel quadro della nuova strutturazione dello stato e della società, la comunità copta fu integrata all interno di una nuova comunità, di cui l appello alla nazione divenne uno dei principali pilastri.

VULNERABLE LANDSCAPES BETWEEN PERCEPTION AND RESILIENCE: THE CASE STUDIES OF THE ISLAND OF MADEIRA AND CINQUE TERRE The research has been finelized to define and intepret vulnerable landscapes, with the hypothesis that this representation and its critical explanation can be the starting point for a new analysis of the territory and for the improvement of effective policies for a Disaster Management. In her work, the author has tried to conceptualize teoretically and operationally the landscapes of vulnerability, with the purpose to suggest new strategies for building resilience and reduce community exposure. The author has discussed a local, integrative and periscope approach of analysis in the Disaster Risk Reduction studies. In literature, several kind of vulnerable landscapes have been discussed, according to environmental and risk characteristics of the territory; in particular, three vulnerable landscapes have been identified: riskscapes, hazardscapes and disasterscapes. All the vulnerable landscapes mentioned have been defined analysing the different level of vulnerability, perception and resilience, and according to the kind of natural events. Landscape is a frail concept, continually subjected to changes and alterations originated from the kind of human approach to the nature. Thus, landscape, as a reality in the making, isn’t a stable entity, so that social dynamics and environmental processes can impact irreversibly on its geomorphology. Understanding the processes and dynamics that impact on the landscape is a key step in Disaster Prevention and Disaster Risk Reduction. Indeed, as a consequence of the climate change, an increasing number of natural events are affecting people, environments and cultural heritage. Therefore, in order to define the vulnerable landscapes in Cinque Terre and in the island of Madeira, the author has started with a critical conceptual discussion of the vulnerability, perception and resilience of the landscapes at risk, and adopting a place-based approach. In the last section of the thesis, the concept of resilientscape has been introduced and analysed, valuating potentiality and limits of the concept for a Disaster Risk Reduction. Then, some approaches to participation and resilience education have been experimented in the context of the island of Madeira. During the research work, three levels of analysis have been adopted: objective risk (in which different kinds of geo-physical risk and of the relationships beween society and nature have been investigated), risk perception (the level of risk perception of the local stakeholders involved in landscape management) and landscape resilience (actions improved in order to increase the local capacity to deal with hazards and to reduce future level of risk). The analysis of physical contexts, anthropic processes and social representation is central in Disaster Prevention. Thus, a reflection on landscape representations is required. Moreover, risk and vulnerability should be considered during the social building of local representation. Then, the results of empirical analysis in the two areas of study have been compared in order to understand potentiality and limits of landscape analysis in Disaster Risk Reduction. In order to reach the goals of the research, the work has been divided in three phases, that correspond to the three parts of the thesis. The first phase reflects and conceptualizes teoretically the key-concepts of the research. This phase has required the analysis of sources (bibliographic, cartographic, iconographic sources, historical representations and satellite images). The sources have provided important data on local risk. Moreover, it has let to “measure” the historical vulnerability in Cinque Terre and Madeira island. The second phase has been aimed at understanding local risk perception. In order to do it, 60 interviews have been realized in Cinque Terre and Madeira and 300 surveys in the island of Madeira. In the surveys the author adpoted tools already experimented in national and international research. The third phase has been destinated to research on the field (participative observation and work-research). According to the results, the research work let to collect information and data, make direct contact with local and (when and where it has been possible) to participate to the processes of resilience building. The results show that the island of Madeira and Cinque Terre are lanscapes where natural hazards happen frequently. The origins of these natural processes must be traced in the man-work of landscape building and changing and in the abandonment of the rural areas. The promotion and representation of the landscapes in Madeira and Cinque Terre is mainly driven to preserve the tourrism in the region (the tourism is the first economic income in the two areas) and to reduce the perception of the landscape at risk and of the riskscape. Therefore, the landscapes of Cinque Terre and Madeira island appeare as vulnerable landscapes, in which interesting resilience examples have place and could participate in the building of a future resilientscape.
I PAESAGGI VULNERABILI TRA PERCEZIONE E RESILIENZA: L’ISOLA DI MADEIRA E LE CINQUE TERRE COME CASI DI STUDIO. Il lavoro di ricerca è stato teso alla definizione e interpretazione di un paesaggio vulnerabile, nell’ipotesi che questa rappresentazione, e la sua esplicitazione critica, sia la premessa per letture del territorio e politiche efficaci per la gestione del rischio. Il lavoro di tesi ha cercato, pertanto, di concettualizzare teoricamente e operativamente i paesaggi della vulnerabilità cercando di proporre una nuova tipologia di questa analisi che possa aiutare nella costruzione di processi resilienti in grado di ridurre l’esposizione delle comunità ai disastri. Si è cercato, cioè, di presentare un nuovo approccio di analisi alla disaster risk reduction, con carattere locale, integrato e periscopico. In letteratura sono stati definiti diversi tipi di paesaggio vulnerabile in ragione delle dinamiche ambientali e dei rischi presenti sul territorio; in particolare sono stati identificati i riskscapes, gli hazardscapes, e i disasterscapes, definiti dalle diverse interazioni entro vulnerabilità, resilienza e percezione. Il paesaggio è una realtà fragile, sottoposta a continui mutamenti e alterazioni che discendono dall’opera dell’uomo e della natura. In quanto realtà in divenire, il paesaggio non è un’entità stabile, e dinamiche sociali e processi ambientali possono avere impatti irreversibili su di esso. Comprendere le dinamiche e i processi che agiscono sul paesaggio è fondamentale nella prevenzione dei disastri e nella riduzione dei rischi che popolazioni, ambiente e patrimonio oggi vivono in misura crescente, a conseguenza anche del cambiamento climatico. Per giungere a una definizione del paesaggio vulnerabile nelle Cinque Terre e a Madeira sono stati, pertanto, indagati la vulnerabilità, la percezione e il livello di resilienza del paesaggio al rischio, partendo dallo studio del locale. Infine, è stato discusso cosa sia un paesaggio resiliente (potenzialità e limiti del concetto nella riduzione del rischio di disastri) e come costruirlo in un contesto sperimentale quale l’isola di Madeira. Durante il lavoro di ricerca sono stati adottati tre livelli di analisi: rischio oggettivo (nel quale sono state discusse le diverse tipologie di rischio geo-fisico presenti nelle aree di studio e le dinamiche società-ambiente che accrescono o producono questi rischi), rischio percepito (in particolare, è stato analizzato il livello di percezione del rischio degli attori coinvolti nella costruzione del paesaggio), resilienza del paesaggio (per la quale sono state considerate le azioni locali messe in atto per aumentare la capacità di risposta ai disastri e di riduzione del rischio). Nella prevenzione dei disastri è fondamentale lavorare non solo sui contesti fisici e sui processi antropici ma anche sulle rappresentazioni che i diversi attori hanno del rischio di eventi naturali. Si tratta, perciò, di riflettere e contribuire alla costruzione di rappresentazioni del territorio e, di conseguenza, del paesaggio (come inteso da Raffestin) che incorporino il rischio e la vulnerabilità. I risultati delle analisi empiriche sono stati, poi, comparati al fine di comprendere potenzialità e limiti di un’analisi paesaggistica nel processo di riduzione del rischio di disastri. Per raggiungere gli obiettivi prefissati, il lavoro di ricerca è stato diviso in tre fasi che corrispondono ai tre corpi della tesi. Una prima fase di riflessione concettuale e discussione teorica, a cui segue l’analisi delle fonti (bibliografiche, cartografiche, iconografiche, fotografie storiche e immagini satellitari) che hanno fornito indicazioni e dati sul rischio nelle aree di studio. Questo lavoro ha consentito di definire la vulnerabilità storica dei paesaggi nelle Cinque Terre e sull’isola di Madeira e di comprendere le dinamiche di formazione del rischio attuale. È seguita, poi, una fase di indagine della percezione della popolazione, e a tal proposito sono state realizzate 60 interviste strutturate e semi-strutturate (nell'isola di Madeira e nelle Cinque Terre) e 300 questionari (nell'isola di Madeira). I questionari hanno adottato strumenti di indagine già sperimentati in ricerche scientifiche nazionali e internazionali. Infine, l’ultima fase è stata dedicata alla ricerca di campo (osservazione partecipante e ricerca-lavoro) attraverso la quale è stato possibile raccogliere informazioni, prendere contatto con le realtà locali, e attivare collaborazioni al fine di definire e (onde possibile) incrementare la resilienza locale. I risultati hanno mostrato che l’isola di Madeira e le Cinque Terre sono paesaggi frequentemente interessati da processi naturali a volte disastrosi, le cui origini si possono ritrovare in buona misura nel lavoro di produzione e modificazione del paesaggio operato dall'uomo nel corso dei secoli e dal processo di abbandono delle aree agricole. Entrambe le regioni sono conosciute a livello internazionale per le loro bellezze paesistiche e costituiscono importanti mete turistiche mondiali. Di conseguenza, la promozione e rappresentazione di questi paesaggi è principalmente guidata dalla necessità di preservare il turismo (oggi prima risorsa economica locale) e di ridurre la percezione di un paesaggio del rischio. I paesaggi delle Cinque Terre e di Madeira sono apparsi, pertanto, come paesaggi fortemente vulnerabili. Entro questi paesaggi, tuttavia, si incontrano interessanti esempi di resilienza, che costituiscono delle basi da cui partire per la costruzione di un paesaggio resiliente al rischio.

Protein synthesis in all organisms utilizes a special tRNA called the initiator tRNA. Initiator tRNAs take part in the initiation step of protein synthesis by their direct binding to the P‐site of the ribosome. The other tRNAs (elongator tRNAs) bind first to the A‐site of the ribosome and are subsequently translocated to the P‐site during elongation. The initiator tRNA possesses sequence and structural characteristics, which enable it to perform its unique function in protein synthesis. In addition to the highly conserved three consecutive G:C base pairs in the anticodon stem of the initiator tRNA which facilitate its P‐site binding, bacterial and organellar initiator tRNAs are also formylated by FMT (methionyl‐tRNAfMet formyltransferase) to enable their binding to initiation factor 2 (IF2), directing them specifically into initiation. Structure‐function studies of E. coli initiator tRNA in‐vivo using reporter constructs showed that formylation plays a crucial role in deciding the fate of the initiator tRNA in initiation. The tRNA mutants deficient in formylation take part in initiation and/or elongation. Protein factors like IF2, elongation factor Tu (EF‐Tu) and peptidyl‐tRNA hydrolase (Pth) also contribute to the fate of the tRNA in‐vivo. The current study aims to understand how the balance of protein factors and sequence elements present on a tRNA determine its participation at the steps of initiation and/or elongation using E. coli and M. smegmatis as model organisms. The findings of my research have been described in three distinct investigations as follows: PART‐I. Development of assay systems for amber codon decoding at the steps of initiation and elongation by tRNAfMet derivatives in mycobacteria The bulk of our understanding of the mechanism of protein synthesis in bacteria is derived from the studies in E. coli. The mechanism of translation in Gram positive bacteria remains a relatively less understood process. Gram positive bacteria possess significant differences in their translational apparatus as compared to the Gram negative organisms, and therefore present with interesting systems to understand the mechanism of translation. For example, Gram positive bacteria use an indirect pathway for synthesis of Gln‐tRNAGln and Asn‐tRNAAsn as opposed to direct synthesis of Gln‐tRNAGln by glutaminyl‐tRNA synthetase (GlnRS) in E. coli. We used M. smegmatis, a slow growing Gram positive bacterium, as the model organism to study translation. The understanding of protein synthesis in these bacteria has been limited by the lack of well characterized genetic systems. Using chloramphenicol acetyltransferase (CAT) reporters (having an amber codon as the start codon or as a codon at an internal position within the reading frame of the mRNA), we developed genetic systems where the amber codon is decoded by a mutant initiator tRNA (wherein the CAU anticodon was mutated to CUA with or without additional changes in the acceptor stem) either at the step of initiation or elongation in M. smegmatis, enabling us to measure the efficiency of the mutant tRNAs in initiation or elongation in‐vivo. Characterization of the reporter encoded protein by mass spectrometric analysis showed that initiation in such a reporter proceeds through incorporation of methionine, as opposed to the use of glutamine in similar systems in E. coli. Elongation in the reporter system, carried out by formylation deficient mutants of the initiator tRNA, was found to occur through the insertion of glutamine using a two‐step pathway, where the tRNA is first aminoacylated by a non‐discriminating GluRS, followed by transamidation of the attached Glu by an amidotransferase. The formylation deficient acceptor stem mutants of the initiator tRNA were also recognized differentially by the amidotransferase in‐vivo, leading to the insertion of either glutamate or glutamine during elongation by different mutants of the tRNA. Overall, the study highlighted the conserved nature of formylation across bacteria, and its importance in the exclusive participation of the initiator tRNA in initiation. PART II. Physiological role of tRNAs that function as alternate initiator tRNAs in mycobacteria The genomes of M. tuberculosis and M. smegmatis encode three tRNAs, metU, metV and metT, with CAU anticodons. While metU has been shown to encode the initiator tRNA in these bacteria, the other two (metV and metT) are both annotated as methionine elongator tRNA. Interestingly, these tRNAs also possess some sequence characteristics like the G:C base pairs in the anticodon stem, and the lack of a Watson‐Crick base pair at 1:72 position, which are thought to be restricted to initiator tRNAs. We were interested in understanding the physiological role of such sequence elements present in the elongator tRNA. Computational and biochemical characterization of metT and metV identified them as the methionine decoding elongator tRNA (tRNAMet) and the minor form of the isoleucine decoding tRNA (tRNAIle2), respectively. Mass spectrometric analysis of metV showed that the C34 in the anticodon of the tRNA is modified to lysidine, which is consistent with its role in AUA decoding. Interestingly, the expression of metV is upregulated under stress conditions. Analysis of the modification status of the tRNA under hypoxic conditions showed that the tRNA is undermodified for lysidine, which would preclude its function in AUA decoding and enable it to function as tRNAMet. We propose that this could be a mechanism of regulation employed by cells under hypoxia. In‐vivo assays using the CAT reporter showed that metV is capable of initiating protein synthesis, providing support to our hypothesis that such tRNAs could function as alternate initiator tRNAs under stress conditions. PART III. Mitochondria‐like sustenance of E. coli on a single tRNAfMet Most organisms possess distinct methionine tRNAs that participate at the steps of initiation and elongation. However, protein synthesis in mammalian mitochondria utilizes only a single tRNAMet, which functions in both initiation and elongation. The partitioning of tRNA into initiation and elongation phases is thought to occur due to the competition between EF‐Tumt (which directs the tRNA to the elongation step) and Fmtmt (which, following formylation, directs the tRNA to the initiation step), for their binding to the single species of Met‐tRNAMet. Our studies on initiator tRNA from mycobacteria, along with the available literature on mutants of E. coli initiator tRNA, show that some mutants of initiator tRNA are capable of participating at the step of elongation. Similarly, as shown in Part‐II of the results section, native elongator tRNAs capable of initiating protein synthesis also exist in some organisms. We therefore asked if in E. coli, a single tRNAMet could participate at both the steps of initiation and elongation (as in mitochondria), and if such tRNAs fulfill the cellular needs at both steps. Using a transduction based genetic strategy, we have shown that many acceptor stem mutants of the initiator tRNA sustain E. coli for initiation and elongation function separately. Importantly, a subset of these mutants also sustains the growth of E. coli devoid of all the six copies of methionine tRNA genes (four of initiators and two of elongators). Furthermore, the mutant tRNA which is most efficient at sustaining the cell is also the one which is most like mitochondrial tRNAMet. Overall, the study provides insights into how distribution of the tRNA between FMT/IF2 and EF‐Tu determines its role in protein synthesis.

碩士
國立高雄應用科技大學
觀光與餐旅管理系
100
In order to welcome the hundredth year of Taiwan as well as to remember the historical ninety-ninth year, Taiwan Railways Administration (TRA) promoted a series of commemorative train and platform tickets for people to collect. Using distinguished trains from twelve generations, TRA held “A Relay of Train to Go around Taiwan, and a Sightseeing Tour of Stations in Year 100,” a celebration and a theme tour of cruise style trains. Travel helps improving our inner and outer health, individual benefit, and lifestyle quality. In addition to the multiplicity of domestic tours, the cruist style trains not only work as transportation but also provide tourists a process of experience. Cruise style trains are limited by the existing railway line, and there is restriction on the itinerary; therefore, attractive features of tourist attractions may affect operation of cruise style trains. Due to the facts above, this thesis focuses on knowing the traveling features of the tourists from the tour of South-Link Line. That is, the differences of tourists’ social and economic backgrounds make to the attractiveness, participating motivation, recreational experience, satisfaction, and loyalty of the tour. Seven hundred and forty-two questionnaires are distributed, 716 of them are valid, and the effective response rate is 96 percent. Based on SPSS 17.0 statistics software analysis, descriptive statistics, factor analysis, t-verification, one-way ANOVA, and Multiple Regression Analysis are used as the methodology of the thesis. The results are as follows: 1) Most of them are ‘first-time’ visitors and they have no interests in buying souvenirs; 2) Attractiveness brings positive influences on participating motivation, recreational experience, satisfaction, and loyalty; 3) Participating motivation brings positive influences on recreational experience, satisfaction, and loyalty; 4) Recreational experience brings positive influences on satisfaction and loyalty; 5) Satisfaction brings positive influences loyalty; 6) There are no significant differences both between ‘first-time’ and ‘revisiting’ tourists and between ‘one-day trip’ and ‘two-day trip’ visitors on the analysis of attractiveness, participating motivation, recreational experience, satisfaction, and loyalty; and 7)To satisfy tourists’ participating motivation and meet their requirement of recreational experience bring positive influences on satisfaction and loyalty. “Related features” of attractiveness, “transportation facilities” and “self-development” of participating motivation, and “facility service” of recreational experience play important roles.

The paper draws from Sergio Caruso’s reflections that the ‘extension’ and ‘intensification’ of citizenship are inseparable from democracy. Within this framework, it questions how innovative formulations of democracy such as so-called ‘deliberative arenas’ can contribute to the strengthening of citizenship. Specific attention is devoted to the public debate on major works, a privileged field of inquiry for some assessments of the effectiveness of participation guaranteed by such instruments.

This paper proposes a brief review of digital resources useful for historians, scholars, professionals and students who want to approach Public History and which can offer opportunities for exploration and participation at several levels. The analysis has been divided into four parts, each starting from an exploration of the Italian context and then moving on to international resources: 1. Web spaces of national and international associations, 2. Oral History and Digital History, 3. Public History Journals , 4. Apps and Databases.

The essay describes how Living History, an activity of concrete evocation of past events in the present, linked to the daily actions of the historical period described, is intertwined with the approach of "material civilization" developed by Fernand Braudel and with micro-history described by Lucien Febvre and March Bloch in connection with the Annales methodology. The re-enactment, if it is built according to correct theoretical and methodological references, linked to historical documents, devoid of folklore, can represent a useful tool for building popular participation and knowledge about events and characters from the past.

The increasing trend in the use of Internet-based emarketplace applications has created tremendous opportunities for businesses to manage effective supply chain management. An electronic market exists when a supplier provides goods and services to a customer in a transaction partially or fully automated by information technology. E-Marketplaces can be defined as a digital infrastructure that supports industrial commerce, such as auctions, catalogues and exchanges (Ivang & Sorenson, 2005). IDC predicts IT and e-marketplace spending will reach $496.7 billion in the U.S. and $1.3 trillion globally by the year 2009. Despite extensive research on this topic, there has been limited work in the realm of e-marketplace security. These e-marketplaces are generally implemented on the Internet, whose original purpose was to provide a robust heterogeneous distributed computing environment for applications that may not yet be developed. Previous researchers have noted that the formation of electronic marketplaces has been declining and that the failure rates are high. For instance, Dai and Kauffman (2002) suggest that only one-fifth of the electronic marketplaces in operation would succeed since firms have to face serious technical challenges. Theoretically e-marketplaces should enable firms to trade and collaborate more efficiently. The reason for this is due to the proliferation of affordable technology and the explosive growth of B2B transactions that have allowed buyers and sellers to conduct transactions electronically and to generate substantial savings and revenue for participants and owners (Sharifi, Kehoe, & Hopkins, 2006). Nevertheless, in reality, many emarketplaces disappeared during major consolidation phase (Tran, 2006).This study aims to examine the nature of security in e-marketplaces. We identify four types of risks, namely economic, technological, implementation, and relational risks in seven e-marketplace firms from a cross-section of different industries. We then present the control measures as in the responses that the seven firms enforced in order to reduce and manage their risks. The contribution of this study is the development of a security framework based on the findings for e-marketplace participation.

Until Professor Trina Grillo’s article warned readers of its process dangers, the family mediation process was viewed as a positive antidote to extensive and costly litigation and as a valuable opportunity for families to work together informally to resolve their custody, support, and property issues. Grillo, an academic and a practicing mediator, asserted that family mediation was not living up to its potential, that mediators hurt women and minorities by mandating participation without lawyers, and that its use created a false sense of empowerment. She was concerned that some mediators were not neutral, failed to focus on clients’ individual needs, and were unable or unwilling to deal with women’s emotions, especially reasonable anger and frustration....

Trina Grillo’s 1991 sounding of alarm bells concerning the impact on women of participating in mediation came as momentum was growing in a nationwide effort to incorporate informal dispute resolution mechanisms in family courts. Her critique was not the first, following on well-known warnings of the effect of an unchecked march toward “alternatives” on economically disadvantaged and racial minority disputants, civil rights enforcement, and society’s general need for court-articulated public norms. Nor was she the first to raise concerns about the vulnerability of women as participants in mediation. So why is her article so noteworthy?...

Learning languages is not only beneficial for the quality of life of the elderly and their active participation in society, but it also has an important role in stimulating and maintaining their cognitive resources, increasing cognitive reserves and countering their decline, favouring the development of compensatory processes. From this point of view, learning languages in old age is not only possible but it is desirable. All of this justifies a FL geragogic model based on the idea that education must respect teaching methods principles especially when aimed at the elderly. Since memory consists of different processes which interact with each other affecting several brain areas, there is no unitary ageing of memory in the elderly. Some types of memory are very sensitive to ageing, while others are very well preserved and show no signs of deterioration. Therefore, from the perspective of the language education of the elderly, it is necessary to know the different features of memory ageing in order to prepare teaching activities and educational paths that take into account the specific characteristics and changes that affect memory over the years.

L'aumento delle temperature, lo scioglimento dei ghiacciai, la maggiore frequenza degli episodi di siccità e di alluvioni sono tutti sintomi della dissonanza tra attività antropiche e fenomeni naturali, dei cambiamenti climatici in atto. I rischi per il pianeta e per le generazioni future saranno incalcolabili se non s’interverrà con urgenza a partire proprio dalle nuove generazioni. Per questo, quando si parla di politiche urbane, è indispensabile che si tenga presente che esistono cittadini, che la loro partecipazione, il loro coinvolgimento nella cura del territorio rappresenta la strategia migliore per guidare le trasformazioni urbane; garantirsi una migliore qualità della vita e garantirla ai luoghi. Produrre inclusione sociale significa assicurare la realizzazione degli interventi. La memoria del passato, la condivisione, la trasparenza nell’informazione, la consapevolezza di far parte di una collettività attiva permette di salvaguardare l’identità storica di un luogo e di una popolazione. Rising temperatures, melting glaciers, the increased frequency of droughts and floods are all symptoms of dissonance between human activities and natural phenomena, of climate changes. The risks for the planet and for future generations will be incalculable if we not intervene urgently, starting from the new generations. For this reason, when it comes to urban policies, it is imperative that you understand that there are citizens, their participation, their involvement in the care of the land is the best strategy to guide urban transformations; ensure a better quality of life and ensure it to places. Produce social inclusion means ensuring the implementation of the interventions. The memory of the past, sharing, transparency of information, awareness of being part of a community active allows to preserve the historical identity of a place and of a population

The developments in the field of technology in the 21st century caused changes in the field of education, as in many fields. Technology undoubtedly facilitates human life when used properly. There are many benefits to using technology in education.Technology today makes people's lives easier and progresses rapidly with it. In the process of integration of developing technologies into the field of education, important studies are carried out on the international platform. In the 21st century world, as well as changes in every field, various innovations in science and technology have occurred. Education plays an important role in keeping up with the requirements of the present era. Technological innovations and developments affect the education system and teaching learning-process in this context. The technologies used in education are leaving their place to new technologies. Increasingly, they take their place in the classroom environment such as computer, projection, electronic board, distance education and the learning environment is moved to the network environment (Bulman & Fairlie, 2016; Sendurur & Arslan, 2017). Lectures can be strengthened with technological equipment. On the other hand, using technology in education makes lessons more attractive for students. At the same time, supporting narration with technological tools facilitates learning and increases retention. For this reason, the use and importance of technology in education has increased today and teachers' attitudes towards technology use are important. When evaluated from this point of view, it is thought that the research subject will contribute to the literature. This study aimed to determine primary school teacher candidates' attitudes towards digital technology. In this study, the primary teacher candidates studying at a private university in the Turkish Republic of Northern Cyprus (TRNC) were examined on the technology attitudes of teachers in education. The study was conducted with the participation of 121 teacher candidates during 2019-2020 academic year. Attitude Scale towards the Use of Technology in Education was used to determine the attitudes of prospective teachers towards digital technology. Results are presented with descriptive statistics, tables, frequencies and percentages and discussed with relevant references from the literature and suggestions for future research and practices are provided.