Saccharomyces Cerevisiae as a biotechnological tool for ageing research:studies on translation and metabolism

The yeast Saccharomyces cerevisiae is an important model organism for the study of cell biology. The similarity between yeast and human genes and the conservation of fundamental pathways means it can be used to investigate characteristics of healthy and diseased cells throughout the lifespan. Yeast is an equally important biotechnological tool that has long been the organism of choice for the production of alcoholic beverages, bread and a large variety of industrial products. For example, yeast is used to manufacture biofuels, lubricants, detergents, industrial enzymes, food additives and pharmaceuticals such as anti-parasitics, anti-cancer compounds, hormones (including insulin), vaccines and nutraceuticals. Its function as a cell factory is possible because of the speed with which it can be grown to high cell yields, the knowledge that it is generally recognized as safe (GRAS) and the ease with which metabolism and cellular pathways, such as translation can be manipulated. In this thesis, these two pathways are explored in the context of their biotechnological application to ageing research: (i) understanding translational processes during the high-yielding production of membrane protein drug targets and (ii) the manipulation of yeast metabolism to study the molecule, L-carnosine, which has been proposed to have anti-ageing properties. In the first of these themes, the yeast strains, spt3?, srb5?, gcn5? and yTHCBMS1, were examined since they have been previously demonstrated to dramatically increase the yields of a target membrane protein (the aquaporin, Fps1) compared to wild-type cells. The mechanisms underlying this discovery were therefore investigated. All high yielding strains were shown to have an altered translational state (mostly characterised by an initiation block) and constitutive phosphorylation of the translational initiation factor, eIF2a. The relevance of the initiation block was further supported by the finding that other strains, with known initiation blocks, are also high yielding for Fps1. A correlation in all strains between increased Fps1 yields and increased production of the transcriptional activator protein, Gcn4, suggested that yields are subject to translational control. Analysis of the 5´ untranslated region (UTR) of FPS1 revealed two upstream open reading frames (uORFs). Mutagenesis data suggest that high yielding strains may circumvent these control elements through either a leaky scanning or a re-initiation mechanism. In the second theme, the dipeptide L-carnosine (ß-alanyl-L-histidine) was investigated: it has previously been shown to inhibit the growth of cancer cells but delay senescence in cultured human fibroblasts and extend the lifespan of male fruit flies. To understand these apparently contradictory properties, the effects of L-carnosine on yeast were studied. S. cerevisiae can respire aerobically when grown on a non-fermentable carbon source as a substrate but has a respiro-fermentative metabolism when grown on a fermentable carbon source; these metabolisms mimic normal cell and cancerous cell metabolisms, respectively. When yeast were grown on fermentable carbon sources, in the presence of L-carnosine, a reduction in cell growth and viability was observed, which was not apparent for cells grown on a non-fermentable carbon source. The metabolism-dependent mechanism was confirmed in the respiratory yeast species Pichia pastoris. Further analysis of S. cerevisiae yeast strains with deletions in their nutrient-sensing pathway, which result in an increase in respiratory metabolism, confirmed the metabolism-dependent effects of L-carnosine.

Exploration of metaphors used by Indonesian legislators and political elites in the Indonesian sociopolitical domain

This thesis examines the ways Indonesian politicians exploit the rhetorical power of metaphors in the Indonesian political discourse. The research applies the Conceptual Metaphor Theory, Metaphorical Frame Analysis and Critical Discourse Analysis to textual and oral data. The corpus comprises: 150 political news articles from two newspapers (Harian Kompas and Harian Waspada, 2010-2011 edition), 30 recordings of two television news and talk-show programmes (TV-One and Metro-TV), and 20 interviews with four legislators, two educated persons and two laymen. For this study, a corpus of written bahasa Indonesia was also compiled, which comprises 150 texts of approximately 439,472 tokens. The data analysis shows the potential power of metaphors in relation to how politicians communicate the results of their thinking, reasoning and meaning-making through language and discourse and its social consequences. The data analysis firstly revealed 1155 metaphors. These metaphors were then classified into the categories of conventional metaphor, cognitive function of metaphor, metaphorical mapping and metaphor variation. The degree of conventionality of metaphors is established based on the sum of expressions in each group of metaphors. Secondly, the analysis revealed that metaphor variation is influenced by the broader Indonesian cultural context and the natural and physical environment, such as the social dimension, the regional, style and the individual. The mapping system of metaphor is unidirectionality. Thirdly, the data show that metaphoric thought pervades political discourse in relation to its uses as: (1) a felicitous tool for the rhetoric of political leaders, (2) part of meaning-making that keeps the discourse contexts alive and active, and (3) the degree to which metaphor and discourse shape the conceptual structures of politicians‟ rhetoric. Fourthly, the analysis of data revealed that the Indonesian political discourse attempts to create both distance and solidarity towards general and specific social categories accomplished via metaphorical and frame references to the conceptualisations of us/them. The result of the analysis shows that metaphor and frame are excellent indicators of the us/them categories which work dialectically in the discourse. The acts of categorisation via metaphors and frames at both textual and conceptual level activate asymmetrical concepts and contribute to social and political hierarchical constructs, i.e. WEAKNESS vs.POWER, STUDENT vs. TEACHER, GHOST vs. CHOSEN WARRIOR, and so on. This analysis underscores the dynamic nature of categories by documenting metaphorical transfers between, i.e. ENEMY, DISEASE, BUSINESS, MYSTERIOUS OBJECT and CORRUPTION, LAW, POLITICS and CASE. The metaphorical transfers showed that politicians try to dictate how they categorise each other in order to mobilise audiences to act on behalf of their ideologies and to create distance and solidarity.

Identifying frames:a comparison of research methods

Framing plays an important role in public policy. Interest groups strategically highlight some aspects of a policy proposal while downplaying others in order to steer the policy debate in a favorable direction. Despite the importance of framing, we still know relatively little about the framing strategies of interest groups due to methodological difficulties that have prevented scholars from systematically studying interest group framing across a large number of interest groups and multiple policy debates. This article therefore provides an overview of three novel research methods that allow researchers to systematically measure interest group frames. More specifically, this article introduces a word-based quantitative text analysis technique, a manual, computer-assisted content analysis approach and face-to-face interviews designed to systematically identify interest group frames. The results generated by all three techniques are compared on the basis of a case study of interest group framing in an environmental policy debate in the European Union.

An empirical examination of emotional and cognitive responses to threat appeals

Advertising and other forms of communications are often used by government bodies, non-government organisations, and other institutions to try to influence the population to either a) reduce some form of harmful behaviour (e.g. smoking, drunk- driving) or b) increase some more healthy behaviour (e.g. eating healthily). It is common for these messages to be predicated on the chances of some negative event occurring if the individual does not either a) stop the harmful behaviour, or b) start / increase the healthy behaviour. This design of communication is referred to by many names in the relevant literature, but for the purposes of this thesis, will be termed a ‘threat appeal’. Despite their widespread use in the public sphere, and concerted academic interest since the 1950s, the effectiveness of threat appeals in delivering their objective remains unclear in many ways. In a detailed, chronological and thematic examination of the literature, two assumptions are uncovered that have either been upheld despite little evidence to support them, or received limited attention at all, in the literature. Specifically, a) that threat appeal characteristics can be conflated with their intended responses, and b) that a threat appeal always and necessarily evokes a fear response in the subject. A detailed examination of these assumptions underpins this thesis. The intention is to take as a point of departure the equivocality of empirical results, and deliver a novel approach with the objective of reducing the confusion that is evident in existing work. More specifically, the present thesis frames cognitive and emotional responses to threat appeals as part of a decision about future behaviour. To further develop theory, a conceptual framework is presented that outlines the role of anticipated and anticipatory emotions, alongside subjective probabilities, elaboration and immediate visceral emotions, resultant from manipulation of the intrinsic message characteristics of a threat appeal (namely, message direction, message frame and graphic image). In doing so, the spectrum of relevant literature is surveyed, and used to develop a theoretical model which serves to integrate key strands of theory into a coherent model. In particular, the emotional and cognitive responses to the threat appeal manipulations are hypothesised to influence behaviour intentions and expectations pertaining to future behaviour. Using data from a randomised experiment with a sample of 681 participants, the conceptual model was tested using analysis of covariance. The results for the conceptual framework were encouraging overall, and also with regard to the individual hypotheses. In particular, empirical results showed clearly that emotional responses to the intrinsic message characteristics are not restricted to fear, and that different responses to threat appeals were clearly attributed to specific intrinsic message characteristics. In addition, the inclusion of anticipated emotions alongside cognitive appraisals in the framework generated interesting results. Specifically, immediate emotions did not influence key response variables related to future behaviour, in support of questioning the assumption of the prominent role of fear in the response process that is so prevalent in existing literature. The findings, theoretical and practical implications, limitations and directions for future research are discussed.

Smartphone chronic gaming consumption and positive coping practice

Purpose - Chronic consumption practice has been greatly accelerated by mobile, interactive and smartphone gaming technology devices. This study explores how chronic consumption of smartphone gaming produces positive coping practice. Design/methodology/approach - Underpinned by cognitive framing theory, empirical insights from eleven focus groups (n=62) reveal how smartphone gaming enhances positive coping amongst gamers and non-gamers. Findings - The findings reveal how the chronic consumption of games allows technology to act with privileged agency that resolves tensions between individuals and collectives. Consumption narratives of smartphone games, even when play is limited, lead to the identification of three cognitive frames through which positive coping processes operate: (a) the market generated frame, (b) the social being frame, and (c) the citizen frame. Research limitations/implications – This paper adds to previous research by providing an understanding of positive coping practice in the smartphone chronic gaming consumption. Originality/value - In smartphone chronic gaming consumption, cognitive frames enable positive coping by fostering appraisal capacities in which individuals confront, hegemony, culture and alterity-morality concerns.