Exploring several nonconventional interactions of ice-binding proteins

Traditionally, ice-binding proteins (IBPs), also known as antifreeze proteins (AFPs), have been defined by two universal activities: ice recrystallization inhibition and thermal hysteresis. However, there remains the possibility IBPs have other complementary functions given the diversity found within this protein group. This thesis explores some of these in both natural and applied settings, in the hopes of furthering our understanding of this remarkable group of proteins. Plant IBPs could function as part of a defensive strategy against ice nucleators produced by certain pathogens. To assess this hypothesis, recombinant IBPs from perennial ryegrass and purple false brome were combined with the ice nucleation protein (INP) from the plant pathogen, Pseudomonas syringae. Strikingly, the plant proteins depressed the freezing point of the bacterial INP, while a fish AFP could not, nor did the INPs have any effect on IBP activity. Thus, the interaction between these two different proteins suggests a role in plant defensive strategies against pathogenic bacteria as another IBP function. In addition, the potential use of hyperactive insect IBPs in organ preservation was investigated. Current kidney preservation techniques involve storing the organ at 4 °C for a maximum of 24 h prior to transplantation. Extending this “safe” time would have profound effects on renal transplants, however, ischemic injury is prevalent when storage periods are prolonged. Experiments described here allowed subzero preservation for 72 h with the addition of a beetle IBP to CryoStasis® solution. Kidneys stored using the traditional technique for 24 h and the method developed here for 72 h showed similar levels of biomarker enzymes, underscoring the potential utility of insect IBPs for future transplant purposes. Finally, IBP function in the freeze-tolerant gall fly, Eurosta solidaginis, was examined. Larvae representing the mid-autumn stage displayed ice-binding activity, suggesting an IBP is being expressed, possibly as a protective measure against freezing damage when fall temperatures can unpredictably drop. IBP activity was also observed in the larvae’s host plant, Solidago spp. Mass spectrometry analysis of ice-affinity purified plant extracts provided three candidate pathogenesis-related proteins that could be responsible for the detected activity, further demonstrating additional functions of IBPs.

WHEN INTERACTING ONLINE LEADS TO TAKING ACTION OFFLINE: EXAMINING THE EFFECTS OF ONLINE PERSUASION ON IS USERS’ PRO-ENVIRONMENTAL BEHAVIOURS

With the increasing attention towards the role of information systems (IS) as a vehicle to address environmental issues, IS researchers and practitioners have strived to leverage advanced Green IS innovations to persuade people to engage in environmentally responsible practices and support pro-environmental initiatives. Yet, existing research reveals that the persuasion effects of Green IS designs remain equivocal. In particular, many design characteristics advocated in Green IS research can produce bi-directional changes in IS users’ attitudes and behaviours. To address this issue, this thesis drew upon the circumplex model of social values (S.H. Schwartz, 1992) to explain when and how online persuasion designs come to affect people’s judgements on resource conservation and environmental protection. Three sets of working propositions and specific hypotheses were developed. Specifically, this research suggests that the use of an IS application can elicit different value primes and draw IS users’ attentions to different motivational functions of engaging in suggested behavioural changes. It is expected that matching online persuasion appeals with IS users’ personal value priorities can increase users’ acceptance of online behavioural suggestions. Second, it is hypothesized that the persuasion effect tends to be weakened, as the system users become aware of the valuematching design in a given IS application. Third, it is proposed that different value primes presented in an IS application can result in different unintended effects on IS users’ global pro-environmental attitudes and motivations. The hypotheses were tested in the two pilot studies and two full-scale online experiments. The study findings generally support the main predictions of the hypotheses. On the one hand, this thesis providesiii empirical evidence that IS design for online persuasion can be instrumental in influencing IS users’ judgements on a range of resource conservation practices. On the other hand, this work explains why the effectiveness of IS-enabled online persuasion attempts needs to be measured not only in terms of the intended changes in a target behavioural domain but also in terms of unintended changes in people’s general environmental orientations. Findings in this research may bring a different perspective on understanding and assessing the influence of Green IS applications on IS users’ judgements and behaviou