• Large-scale studies and biophysical analysis of systems involved in plant immunity.

      Kuai, Xiahezi; Centre for Biotechnology
      The field of plant immunity has progressed significantly in the last decade, driven primarily by both forward and reverse genetics and to a lesser extent by molecular biology techniques. However, many unknowns still remain before a more complete picture of this system can be achieved, which hinders our capacity to develop biotechnological solutions to ensure food safety for our growing population. Some of the problems that still need to be tackled relate to the multi-system involvement of some proteins, the interrelation of the different hormones, such as in trade-off systems, and the challenges of translating existing molecular knowledge into crop protection strategies. The goal of this thesis was to develop new methods and to adapt existing ones to address the challenges and push the boundaries of our knowledge of plant immunity as a system. We have adapted ClueGO analyses to visualize functionally grouped Gene Ontology (GO) terms specific to Arabidopsis. We developed a transcription factor- coregulator identification strategy based on double-transcriptome analyses. Finally, we have adapted a biophysical method, differential scanning fluorimetry (DSF). We tested the usefulness of these methods by interrogating different immune proteins/genes of the model plant Arabidopsis thaliana. Here is a summary of the major results obtained. In the realm of basal immunity, we discovered that clade I TGA transcription factors positively regulate this system by repressing WRKY transcription factors, which are negative regulators of the process. Furthermore, we have demonstrated that clade I TGA integrates into the growth- immunity trade-off system regulated by brassinosteroids by antagonizing the brassinosteroids-dependent suppression of basal immunity. In the realm of systemic acquired resistance (SAR), we have demonstrated that clade I TGA recruits a specific novel glutaredoxin as a corepressor to dampen the expression of a set of SAR-regulated genes controlled by salicylic acid (SA) and the SAR-orchestrator, NPR1. Finally, we demonstrated that NPR1 binds SA and that this interaction leads to the destabilization of NPR1. More importantly, the method used to show the latter is scalable and can be used to develop novel chemistries capable of deploying plant immunity in the field.
    • The Larger Stages: The 'Becoming Minor' of South African Theatres.

      Planche, Jill; Interdisciplinary Humanities Program
      ABSTRACT The Larger Stages: The Becoming ‘Minor’ of South African Theatres. By Jill Planche South Africa is layered with entangled histories that have created a fragile landscape of ambiguities where fractured memories are revealed yet remain concealed. The social architecture of apartheid still persists in a legacy of hostile urban geographies and land inequity, while global capitalism and economic disparity are seen in the dramatic contrast between the developing middle class and the poverty of millions. This research project interrogates the way in which contemporary theatre in South Africa is implicated in the country's complex cultural, economic and social realities. Pursuing rigorous qualitative research in the history, practice and criticism of South African theatre; contemporary studies in theatre spatiality; and philosophy, cultural theory and human geography, I explore precisely whose voices are being heard and which audiences are being reached. What role does – and might – theatre play in addressing South Africa’s socio-economic and artistic challenges, both as a barrier and a bridge to audiences? Drawing on the work of such thinkers as Gilles Deleuze, Félix Guattari, Rosi Braidotti and Achille Mbembe, can we anticipate what we might describe as a ‘minor’ theatre that will tell the stories that resonate twenty years after the end of apartheid? The term ‘minor’ refers to the Deleuzian concept of affirmative and dynamic processes to create new political subjects; processes of “becoming” that break from the fixed, proscribed “being,” which in the South African context has been created by centuries of colonialism and decades of state-imposed racial construction. Given the insights afforded by such theorization, I argue that the spaces of performance are potentially dynamic spaces of intersection within this landscape of layered socio-economic and artistic challenges created by a milieu of rooted physical and mental boundaries that have informed the country’s inherited theatrical practices.
    • Leadership and its impact on the success of Social Sciences and Humanities Research Council funded collaborative research projects

      Chandler, Frances; Department of Graduate and Undergraduate Studies in Education (Brock University, 2011-10-18)
      This dissertation investigates the practice of leadership in collaboratively designed and funded research in a university setting. More specifically, this research explores the meaning of leadership as experienced by researchers who were, or still are, engaged on Social Sciences and Humanities Research Council (SSHRC) funded collaborative research projects in a university setting. This qualitative study (Gay & Airasian, 2003) is situated within a social constructivist paradigm (Kezar, Carducci, & Contreras-McGavin, 2006) and involves an analysis of the responses from 12 researchers who answered 11questions related to my overarching research question: What is the impact of leadership on university based collaborative research projects funded by the Social Sciences and Humanities Research Council based on the experiences of researchers involved? The data that emerged supported and enhanced the existing literature related to leadership and collaborative groups in academia. The type of preferred leadership that emerged as a result of this research seemed to indicate that the type of leader that appeared to be optimal in this context might be described as a functional collaborative expert.
    • Leading Restorative Change: A Case Study of Implementing and Sustaining Restorative Culture in an Ontario Middle School

      Webb, Owen D.; Department of Graduate and Undergraduate Studies in Education
      In February of 2008, the Government of Ontario released legislation for Progressive Discipline in Ontario schools. As a means of fulfilling this legislation, some school districts in Ontario implemented the use of restorative practices. Restorative practices are viewed as a positive means for transforming the culture of a school, yet literature suggests some concerns with restorative approaches. While the practice has been used intermittently across the province of Ontario, seen in some districts or in individual schools, there has not been widespread implementation. Literature suggests that the theoretical foundations of restorative practices are not strong. To enrich literature on restorative culture change, there needs to be ongoing assessment of restorative paradigm shifts in schools. The research addresses the need for studying the leading of restorative culture change from a relational perspective. This research undertook a qualitative case study methodology of a middle school in southern Ontario, examining the school’s journey to implement and sustain a restorative culture. The study looked at the role of leadership in pursuing a restorative vision, the response to the vision by the school community, and how restorative practices are employed by the school. The research revealed the value of restorative practices in establishing space, processes, attitudes, and key questions for initiating dialogue, each critical to establishing a strong relational culture. The need for leadership to continually model restorative practices in order that they are established throughout the organization is necessary for sustaining a restorative culture. Finally, the study showed that evaluating the effectiveness of restorative practices using a relational and dialogic paradigm is critical for founding and sustaining a restorative vision, thereby establishing a strong foundation for effective student learning.
    • Learning and recognizing faces across variability in appearance: An examination of children and older adults

      Matthews, Claire M.; Department of Psychology
      Recognizing facial identity requires two skills: telling a person apart from similar looking people and recognizing them across changes in their appearance. Until recently, the vast majority of studies relied on tightly controlled images to examine face learning and recognition. Research using ambient images (i.e., images that capture within-person variability in appearance) is necessary to assess the true challenge of face learning and recognition in daily life. Only a few studies have examined face learning and recognition using ambient images in children, and, to the best of my knowledge, no studies have examined them in older adults. My dissertation was designed to address these gaps in the literature. In Study 1, children aged 6 to 11 were tested to examine two mechanisms that underlie face learning in young adults: Ensemble coding and the ability to benefit from exposure to variability in appearance in a perceptual matching task. My results revealed that both mechanisms are adultlike by the age of 6. First, children extracted the average of a set of images of an identity, regardless of whether those images were presented simultaneously or sequentially. Second, although their overall accuracy was lower than that of young adults, children showed comparable benefit from viewing multiple images of a to-be-learned identity in a perceptual face learning task. In Study 2, I examined whether younger children (4- and 5-year-olds) benefit from exposure to multiple images when learning a new face in a perceptual task. Although viewing multiple images made young children more sensitive to identity, it also led them to adopt a less conservative response bias, driven both by an increase in hits and an increase in false alarms. This increase in false alarms was not found for older children and adults in Study 1, suggesting that the ability to benefit from exposure to variability in appearance during face learning is not fully refined before the age of 6. In Study 3, I provided the first examination of face learning and recognition in older adults using a battery of tasks. On three of the five tasks, older adults showed comparable learning and recognition to young adults: 1) Older adults recognized a familiar face without error; 2) they showed ensemble coding of facial identity, regardless of whether the images were presented simultaneously or sequentially and 3) despite making more errors than young adults overall, they showed comparable benefit from viewing multiple images of a newly encountered face in the perceptual learning task. In the remaining two tasks, older adults showed a different pattern than young adults: 1) Older adults made fewer hits and more false alarms than young adults when matching images of wholly unfamiliar faces; and 2) after being exposed to low variability in appearance in a face memory task, older adults became more conservative than did younger adults, despite showing comparable benefits in sensitivity. My results reveal that the same abilities that show prolonged development during childhood are those undergo changes in aging. Collectively, my dissertation provides novel insights about learning and recognizing facial identity during childhood and aging and has important implications for understanding models of face processing.
    • Lessons learned from a critical appraisal of a fall break policy in higher education: A case study

      Pilato, Kelly A.; Applied Health Sciences Program
      The incidence, severity and persistence of mental health issues is increasing across post- secondary campuses (Zivin et al., 2009; Canada Newswire, 2012) with these students now viewed as a high-risk population (Stallman, 2010). Many Canadian universities are implementing a policy for a fall break in hopes of alleviating students’ stress and anxiety in order to improve mental health, heighten retention, and increase academic productivity. To date, there is limited empirical evidence to guide the development of policy and the delivery of effective practices to alleviate school-related stress and anxiety. This thesis is presented as a three paper, manuscript approach. The focus of this project was to appraise the development and implementation of a fall break and then evaluate its effectiveness in an effort to address rising concerns related to mental health for post-secondary students. Three thousand and seventy-one students in years one to four completed a post-break survey during one week in January of 2013, 2014, 2015. Of those, 1019 were male and 2052 female. Thirty-three students varying in years from one to four participated in focus groups in February of 2013, 2014, 2015. Of those 4 were male and 19 were female. Ten faculty from varying faculties and one informant participated in interviews in spring, 2018. Analyses from the surveys revealed that overall, students are in favour of having a fall break. Even though a small percentage of participants perceived their workload to go up before and after the break, 90% of students agree that the fall break was useful in reducing school related stress levels. However, the focus group, faculty and informant interviews revealed that the timing of the fall break had an impact on how students and faculty experienced the break and thus influenced perceptions on the impact that the break had on student mental health. Comprehensive evidence about whether a fall break policy supports or undermines the mental health of students needs to be assessed using a range of indicators before its implementation. This will help post-secondary institutions determine whether a break in the fall semester can be an effective approach to addressing students’ stress and anxiety.
    • The Ligand and Membrane-binding Behaviour of the Phosphatidylinositol Transfer Proteins (PITPa & PITPb)

      Baptist, Matilda; Centre for Biotechnology
      Human Class I phosphatidylinositol transfer proteins (PITPs) exists in two forms: PITPα and PITPβ. PITPs are believed to be lipid transfer proteins based on their capacity to transfer either phosphatidylinositol (PI) or phosphatidylcholine (PC) between membrane compartments in vitro. In Drosophila, the PITP domain is found to be part of a multi-domain protein named retinal degeneration B (RdgBα). The PITP domain of RdgBα shares 40 % sequence identity with PITPα and has been shown to possess PI and PC binding and transfer activity. The detailed molecular mechanism of ligand transfer by the human PITPs and the Drosophila PITP domain remains to be fully established. Here, we investigated the membrane interactions of these proteins using dual polarization interferometry (DPI). DPI is a technique that measures protein binding affinity to a flat immobilized lipid bilayer. In addition, we also measured how quickly these proteins transfer their ligands to lipid vesicles using a fluorescence resonance energy transfer (FRET)-based assay. DPI investigations suggest that PITPβ had a two-fold higher affinity for membranes compared to PITPα. This was reflected by a four-fold faster ligand transfer rate for PITPβ in comparison to PITPα as determined by the FRET assay. Interestingly, DPI analysis also demonstrated that PI-bound human PITPs have lower membrane affinity compared to PC-bound PITPs. In addition, the FRET studies demonstrated the significance of membrane curvature in the ligand transfer rate of PITPs. The ligand transfer rate was higher when the accepting vesicles were highly curved. Furthermore, when the accepting vesicles contained phosphatidic acid (PA) which have smaller head groups, the transfer rate increased. In contrast, when the accepting vesicles contained phosphoinositides which have larger head groups, the transfer rate was diminished. However, PI, the favorite ligand of PITPs, or the presence of anionic lipids did not appear to influence the ligand transfer rate of PITPs. Both DPI and FRET examinations revealed that the PITP domain of RdgBα was able to bind to membranes. However, the RdgBα PITP domain appears to be a poor binder and transporter of PC.
    • Ligand design for molecule-based magnetic and/or conducting materials

      ACHA, ROLAND; Department of Chemistry (Brock University, 2013-06-04)
      Work in the area of molecule-based magnetic and/or conducting materials is presented in two projects. The first project describes the use of 4,4’-bipyridine as a scaffold for the preparation of a new family of tetracarboxamide ligands. Four new ligands I-III have been prepared and characterized and the coordination chemistry of these ligands is presented. This project was then extended to exploit 4,4’-bipyridine as a covalent linker between two N3O2 macrocyles. In this respect, three dimeric macrocycles have been prepared IV-VI. Substitution of the labile axial ligands of the Co(II) complex IV by [Fe(CN)6]4- afforded the self-assembly of the 1-D polymeric chain {[Co(N3O2)H2O]2Fe(CN)6}n•3H2O that has been structurally and magnetically characterized. Magnetic studies on the Fe(II) complexes V and VI indicate that they undergo incomplete spin crossover transitions in the solid state. Strategies for the preparation of chiral spin crossover N3O2 macrocycles are discussed and the synthesis of the novel chiral Fe(II) macrocyclic complex VII is reported. Magnetic susceptibility and Mössbauer studies reveal that this complex undergoes a gradual spin crossover in the solid state with no thermal hysteresis. Variable temperature X-ray diffraction studies on single crystals of VII reveal interesting structural changes in the coordination geometry of the macrocycle accompanying its SCO transition. The second project reports the synthesis and characterization of a new family of tetrathiafulvalene derivatives VIII – XII, where a heterocyclic chelating ligand is appended to a TTF donor via an imine linker. The coordination chemistries of these ligands with M(hfac)2.H2O (M( = Co, Ni, Mn, Cu) have been explored and the structural and magnetic properties of these complexes are described.
    • The light and dark sides of perfectionism : implications for health and well-being

      Sirianni Molnar, Danielle; Department of Psychology (Brock University, 2011-10-14)
      The present work presents two studies that examined the association of perfectionism, operationally defined by Hewi t t and Fl e t t ' s (1991) multidimensional mode l of perfectionism, with health and subjective well-being (SWB). The underlying question of this research was whether perfectionism could be beneficial as well as detrimental to health and well-being, as this is one of the mos t highly debated questions in the current literature. In samples of relatively healthy university students (n = 538) and community adults suffering from various chronic illnesses (n = 772), results from Study One indicated that socially prescribed perfectionism (SPP) is directly associated wi th poor e r he a l th and well-being. Results further showed f rom a personcentered perspective that there is a l a rge group of individuals wi th high levels of SPP and that i t is indeed these individuals who reported the poorest health and lowe s t levels of well-being. Other-oriented perfectionism was found to be unrelated to health and SWB. Findings revealed that when perfectionism is self-imposed (i.e., self-oriented perfectionism; SOP), i t is neither healthy nor unhealthy in an absolute sense. From the variable-centered perspective, this conclusion was supported by the f a c t tha t SOP was associated wi th both positive (e.g., be t t e r mental health and highe r levels of SWB in the student sample), and nega t ive correlates (e.g., higher levels of negative affect, stress, and neuroticism in both samples). Evidence f rom the chronically-ill sample further substantiated this conclusion by showing that there may be an optimal level of SOP, because mode r a t e levels of SOP we r e found to be associated with be t t e r health and highe r levels of SWB, whereas levels tha t we r e too low or too high we r e found to be associated with poor e r health and lowe r levels of SWB. Findings f rom the person-centered approach we r e particularly informative, in that they not only demonstrated tha t unique profiles of
    • The Lived Experience of Nursing Students With Formative Assessment Formally Embedded in Clinical Courses: A Transcendental Phenomenological Study

      Mallet-Boucher, Monique; Department of Graduate and Undergraduate Studies in Education
      The potential of formative assessment (FA) for informing learning in classroom-based nursing courses is clearly established in the literature; however, research on FA in clinical courses remains scarce. This inquiry explored the lived experience of nursing students using transcendental phenomenology and described the phenomenon of being assessed in clinical courses. The research question guiding the study was: How is the phenomenon of assessment experienced by nursing students when FA is formally embedded in clinical courses? Inherent in this question were the following issues: (a) the meaning of clinical experiences for nursing students, (b) the meaning of being assessed through FA, and (c) what it is like to be assessed when FA is formally embedded within clinical experiences. The noematic themes that illuminated the whatness of the participants’ experience were (a) enabled cognitive activity, (b) useful feedback, (c) freedom to be, (d) enhanced focus, (e) stress moderator, and (f) respectful mentorship. The noetic themes associated with how the phenomenon was experienced were related to bodyhood, temporality, spatiality, and relationship to others. The results suggest a fundamental paradigm shift from traditional nursing education to a more pervasive integration of FA in clinical courses so that students have time to learn before being graded on their practice. Furthermore, this inquiry and the literature consulted provide evidence that using cognitive science theory to inform and reform clinical nursing education is a timely option to address the repeated calls from nursing leaders to modernize nursing education. This inquiry contributes to reduce our reliance on assumptions derived from research on FA in nursing classrooms and provides evidence based on the reality of using formative assessment in clinical courses. Recommendations for future research are presented.
    • A Longitudinal Examination of Bidirectional Associations between Subjective Sleep Characteristics and Psychosocial Functioning among University Students

      Tavernier, Royette; Department of Psychology (Brock University, 2014-08-27)
      A number of studies have found a significant link between sleep and psychosocial functioning among university students. A critical examination of this literature, however, indicates that one important gap within the literature is the need for longitudinal studies that specifically test for bidirectional associations between these two constructs. The main purpose of my dissertation was to address this gap by conducting three studies that examined bidirectional associations between sleep and psychosocial functioning among a sample of university students. Participants were 942 (71.5% female) undergraduate students enrolled at a Canadian university, who completed survey assessments annually for three consecutive years, beginning in their first year of university. In the first study, I assessed bidirectional associations between two sleep characteristics (sleep quality and sleep duration) and three psychosocial functioning variables (academics, friendship quality, and intrapersonal adjustment). Results based on cross-lagged models indicated a significant bidirectional association between sleep quality and intrapersonal adjustment, such that more sleep problems predicted more negative intrapersonal adjustment over time, and vice versa. Unidirectional associations indicated that both higher academic achievement and more positive friendship quality were significant predictors of less sleep problems over time. In the second study, in which I examined bidirectional associations between sleep and media use, results provided support only for unidirectional associations; such that more sleep problems predicted increases in both time spent watching television and time spent engaged in online social networking. In the third study of my dissertation, in which I examined social ties at university and sleep quality, results indicated a significant bidirectional association, such that more positive social ties predicted less sleep problems over time, and vice versa. Importantly, emotion regulation was a significant mediator of this association. Findings across the three studies, highlight the importance of determining the direction of effects between different sleep characteristics and various aspects of university students’ psychosocial functioning, as such findings have important implications for both methodology and practice. A better understanding of the nature of the associations between sleep and psychosocial functioning will equip students, parents and university administrators with the tools necessary to facilitate successful adjustment across the university years.
    • A Longitudinal Examination of Indirect Effects involving Parenting, Temperament, and Antisocial Behavior in Adolescence

      Stoner, Amanda Jane; Department of Psychology
      The current dissertation examined whether authoritative parenting was indirectly related to adolescent antisocial behavior over time through adolescent temperament, and whether adolescent temperament was indirectly related to authoritative parenting over time through antisocial behavior. My original contribution to knowledge through this dissertation was to demonstrate the longitudinal, direct and indirect relations between a broad view of parenting, several aspects of temperament, and antisocial behavior during early adolescence. A community sample of 10- to 15-year-old male and female adolescents and their mothers responded to questionnaires at two times spanning 18 months. The dissertation is comprised of three studies, each focusing on a different aspect of temperament: effortful control in Study 1, affiliation in Study 2, and frustration in Study 3. In each study, two different models were tested. In the first model, path analyses were used to simultaneously estimate the direct and indirect effects between each of the Time 1 parenting dimensions (psychological autonomy granting, acceptance-involvement, knowledge, tracking, and limit setting) and Time 2 antisocial behavior through Time 2 adolescent temperament. In the second model, path analyses were used to simultaneously estimate the direct and indirect effects of Time 1 temperament on Time 2 parenting through Time 2 antisocial behavior. The analyses in the current studies used a statistically conservative approach in that the initial levels of both the mediators and outcome variables were controlled for in the path models. Results showed that even with high stability of temperament and antisocial behavior, parenting still related to changes over time in antisocial behavior directly and indirectly through adolescent temperament. Also, even with high stability of antisocial behavior and parenting, temperament still related to changes over time in parenting directly and indirectly through antisocial behavior. Overall, the current dissertation builds on the case for a temperament-based foundation of antisocial behavior, and shows that the link between parenting and antisocial behavior is sometimes indirect through adolescent temperament which itself uniquely accounts for changes in parenting, directly and indirectly through antisocial behavior. Applied implications and suggestions for future research are discussed.
    • Looking in the Mirror of Authenticity: A Self-Study of Teacher Education Practice

      Huizenga, Jack; Department of Graduate and Undergraduate Studies in Education
      This study explored the notion of authenticity within the context of teacher education. A qualitative research approach was chosen employing methods associated with self-study in order to explore the dissonance I experienced as a relatively new teacher educator. The purpose of the study was to explore the significance and potential of authenticity in teacher education. The study involved teacher candidates in an elementary science curriculum and instruction course that I was teaching. Teacher candidates reflected on their learning experiences in a course in which I intentionally applied the concept of authenticity. The study also involved experienced teacher educators whom I engaged in conversations as critical friends. Analysis of the teacher candidates’ reflections revealed that the notion of authentic learning resonated with these soon to be teachers. Analysis of the conversations with teacher educators revealed an important distinction between teaching the subject authentically and teaching the student authentically.
    • Magnetically Interesting Coordination Complexes Based on Macrocyclic Ligands

      Ras Ali, Zineb; Department of Chemistry
      The synthesis and study of select 3d and/or 4f coordination complexes prepared from crown ether and Schiff-base dual compartmental macrocycles are described herein, working towards the discovery and study of new families of macrocyclic-based single molecule magnets (SMMs). Chapter 1 introduces the general theory of magnetism, molecular magnetism and SMMs and provides the reader with a brief overview of the relevant coordination chemistry of the two families of macrocycles. In Chapter 2, two 15-crown-5 complexes [Ln(NO3)3(OH2)2(MeOH)], (where Ln(III) = Tb (I) and Dy (II)) have been prepared and characterized. X-ray diffraction studies reveal the two complexes crystallize as 1-D chains. Variable temperature ac magnetic susceptibility studies reveal that (II) is an SMM with two effective energy barriers, Ueff = 26 K (18 cm−1); τ0 = 4.10 × 10−7 s and Ueff = 41 K (29 cm−1); τ0 = 1.35 × 10−8 s, whereas ab initio studies suggest that the observation of slow relaxation of magnetization in the Tb complex (I) is hindered by the presence of rapid quantum tunneling mechanisms (QTM). Solid state photoluminescence measurements reveal the two complexes have well-resolved f–f transitions, where a Gaussian fit of the fine structure of the highest-energy emission band for the Dy(III) complex allows the Stark splitting of the ground state to be determined. In Chapter 3, select Ln(III) complexes with benzo and dibenzo 15-crown-5 macrocycles were synthesized and characterized. Reaction of Dy(III) together with benzo 15-crown-5 afforded a unique [Dy(OH2)8]3+ complex (III), where the hydrated Dy(III) cation is fully encapsulated within a supramolecular cage formed by three benzo 15-crown-5 macrocycles. Interestingly, the close to perfect square antiprismatic geometry of the 4f ion enhances its axial anisotropy, which suppresses quantum tunnelling mechanisms (QTM) in the ground and first excited states, resulting in the observation of SMM behavior in zero dc field. For this system the magnetic data were further supported by solid-state photoluminescence and ab initio studies, The introduction of a second benzene ring into the organic framework of the macrocycle increases its rigidity, where on coordination to Dy(III), affords the partially encapsulated complex (IV), which displays slow relaxation of magnetisation, consistent with SMM properties. In Chapter 4, the coordination chemistry of a dual compartmental Schiff-base macrocycle H2L3 containing O3O2 and N3O2 cavities was explored together with select 3d and 4f ions. In the first part of this chapter, the coordination chemistry of H2L3 with 3d metal ions is presented, where in the presence of NaOH, the Na(I) ions reside in the O3O2 cavity and the 3d ions occupy the second N3O2 cavity. Three coordination complexes containing Cu(II), Zn(II), and Mn(II) ions were prepared and characterized. The Cu(II), and Zn(II) complexes are monomeric with molecular formulae [CuNa(L3b)ClCH3OH]‧6H2O (V) and [ZnNa(L3b)(CH3COO)(CH3OH)]‧H2O (VI) respectively, while the Mn(II) complex crystallizes as a trimer with stoichiometry [Mn3Na2(L3)2(CH3COO)4]·5.75CH3OH·0.5H2O (VII). For complexes (V) and (VI), nucleophilic addition of the NH of the N3O2 cavity to the carbon atom of the adjacent imine results in a contraction of the N3O2 cavity and the formation of a five-membered imidazoline ring to afford the modified ligand L3b.The magnetic properties of (V) and (VII) are also reported. In the second part of this chapter, coordination of the macrocycle to select 4f ions in the absence of any base afforded the mononuclear complexes [Dy(H2L3)(H2O)2(CH3OH)2]Cl3·CH3OH, (VIII), and [Ln(H2L3)(H2O)3(CH3OH)] Cl3, where Ln(III) = Tb (IX), Er (X), and Gd (XI), in which the Ln(III) ion is coordinated in the O3O2 cavity. Magneto-structural studies on these complexes reveal that the Dy complex has a slightly different structure than the other three complexes, however all four 4f ions crystallize with square antiprismatic geometries, where only the Dy(III) complex (VIII) displays SMM properties.
    • Mechanism of tocopherol transfer by human α-tocopherol transfer protein (α-hTTP)

      Zhang, Wen Xiao; Centre for Biotechnology (Brock University, 2010-10-26)
      Vitamin E is a well known fat soluble chain breaking antioxidant. It is a general tenn used to describe a family of eight stereoisomers of tocopherols. Selective retention of a-tocopherol in the human circulation system is regulated by the a -Tocopherol Transfer Protein (a-TIP). Using a fluorescently labelled a-tocopherol (NBD-a-Toc) synthesized in our laboratory, a fluorescence resonance energy transfer (FRET) assay was developed to monitor the kinetics of ligand transfer by a-hTTP in lipid vesicles. Preliminary results implied that NBD-a-Toe simply diffused from 6-His-a-hTTP to acceptor membranes since the kinetics of transfer were not responsive to a variety of conditions tested. After a series of trouble shooting experiments, we identified a minor contaminant, E coli. outer membrane porin F (OmpF) that co-purified with 6-His-a-hTTP from the metal affinity column as the source of the problem. In order to completely avoid OmpF contamination, a GST -a-hTTP fusion protein was purified from a glutathione agarose column followed by an on-column thrombin digestion to remove the GST tag. We then demonstrated that a-hTTP utilizes a collisional mechanism to deliver its ligand. Furthennore, a higher rate of a-tocopherol transfer to small unilamellar vesicles (SUV s) versus large unilamellar vesicles (LUV s) indicated that transfer is sensitive to membrane curvature. These findings suggest that ahTTP mediated a-Toc transfer is dominated by the hydrophobic nature of a-hTTP and the packing density of phospholipid head groups within acceptor membranes. Based on the calculated free energy change (dG) when a protein is transferred from water to the lipid bilayer, a model was generated to predict the orientation of a-hTTP when it interacts with lipid membranes. Guided by this model, several hydrophobic residues expected to penetrate deeply into the bilayer hydrophobic core, were mutated to either aspartate or alanine. Utilizing dual polarization interferometry and size exclusion vesicle binding assays, we identified the key residues for membrane binding to be F 165, F 169 and 1202. In addition, the rates of ligand transfer of the u-TTP mutants were directly correlated to their membrane binding capabilities, indicating that membrane binding was likely the rate limiting step in u-TTP mediated transfer of u-Toc. The propensity of u-TTP for highly curved membrane provides a connection to its colocalization with u-Toc in late endosomes.
    • Mediated Masculinities: The Forms of Masculinity in American Genre Film, 1990-1999

      McDonald, Terrance H.; Interdisciplinary Humanities Program
      This dissertation mobilizes Brinkema's radical formalism (2014) through Deleuze and Spinoza to read masculinities as forms. Specifically, I closely read Western films and masculine crisis films from 1990 to 1999 to map how cinematic forms constitute the potential to alter normative modes of masculinity. To launch this endeavor, I rely on a theoretical hybrid of Brinkema-Deleuze-Spinoza that foregrounds genre films as vibrant forms of difference. This foregrounding unfolds through an engagement with Altman's theory of film genre (1999), Neale's work on genre films (2000), and Grant's view of film genres as iconography and ideology (2007) as well as the work of Deleyto (2012) and Herzog (2010 and 2012) to re-conceptualize film genre in relation to form. I proceed to use my theoretical hybrid and attention to forms to interrogate film theory as a means of seizing gender and, moreover, masculinities from discourses of representation and spectatorship, which tend to limit readings of gender and masculinities to socio-cultural and political meanings. This interrogation engages Mulvey's revision of screen theory (1975), Rodowick's work on difference (1991, 1994), Perkins's approach to mise-en-scène (1972), Bordwell's neo-formalism and post-theory (1996, 2005, 2006), Sobchack's phenomenological approach to spectatorship and affect (1992, 2004), and del Río's Deleuzian conceptualization of affect and performance (2008). Then, with an insistence on the close reading of cinematic forms, my dissertation undertakes two case studies: the Western and the masculine crisis film cycles of the 1990s. Considering the work of Gates (2006) and Grant (2011) on masculinities in popular cinema, my close readings reveal masculinities as taking shape, assuming structures, and forming as they affect and are affected by relations and becomings. These close readings of cinematic forms generate theoretical speculation that engages masculinities studies research, including Bly (1990), Connell (1995), Kimmel (2006 and 2013), Reeser (2010), and Buchbinder (2013). Through theoretical speculation, my dissertation conceptualizes masculinities as forces of creation that materialize as forms. What is at stake in this dissertation is a methodology that denies transcendent ideals and essentialist claims of masculinity with concepts that harness the potential to continuously read masculinities as what has yet to come.
    • The Mental Representation of Visual Information

      Robitaille, Joel; Department of Psychology
      Despite working in relative independence, the working memory and imagery literatures investigate the mental representation of visual information. Recent reports investigating the neural structure and their associated functional activity responsible for the creation and maintenance of these cognitive representations suggest a significant overlap between these fields of study. Because each field has adopted methodologies that does not allow for a direct comparison of the mental representation described by their respective literatures, it is difficult to determine whether imagery and working memory representations are related. Hence, the current thesis further investigates the properties of the visual representation of visual information to bridge between the imagery and working memory fields. In a first study, I compare the psychophysical properties of simple stimuli commonly used in working memory reports with more complex objects adopted by the imagery field. In the course of three experiments, I demonstrate that the cost of stimulus complexity predominantly affects the quality of the mental representation while still providing evidence of a shared cognitive mechanism driving the formation and maintenance of these representations. In a second study, I evaluate the impact of mental rotation on these mental representations as well as whether the adoption of different paradigms, along with different performance metrics, assess the same cognitive construct. Here again, I show strong evidence in support of a common cognitive mechanism driving the performance across mental manipulation and through assessment methods. Finally, the last study attempted to track the manipulation of these visual representations by applying an encoding model to raw EEG activity. While I show evidence of the orientation-relevant activity during perception, the encoding model does not detect reliable enough activity to allow for tracking the orientation of the stimulus during retention and mental rotation. Together, this thesis provides evidence of a shared cognitive mechanism that drives visual working memory and imagery representation, but tracking these mental representations using EEG activity during manipulation remains unclear.
    • Metaphorical Interpretation: Measuring and Facilitating Growth.

      Kennerly, Catharine Ann; Department of Graduate and Undergraduate Studies in Education (Brock University, 2014-07-14)
      Abstract A total of 378 grade 9 students participated in this study to address the problem that although metaphorical literacy and thought are expected and necessary for success in junior and senior high school and beyond, metaphorical concepts and thought are not required to be explicitly taught to these students. The students were from 20 different classes from 4 levels: English language learners (ELL), school to work (SSTW), applied, and academic. All were from 7 secondary schools within a board in southern Ontario. Nine classes made up the control group and 11 classes made up the treatment group. All classes were given 3 pretests and the posttest. The treatment group was given Socratic lessons and direct instruction on metaphorical thought and expressions during 1 semester and in conjunction with their other classroom material. The pretest scores (TOLD, Peabody, preproverbs concrete, and preproverbs abstract) did not reveal any effect of gender, but the academic students had higher scores than the applied students. The SSTW student results are more variable: (a) for the TOLD test, SSTW scores were between those of the academic and applied students; (b) for Peabody scores, SSTW students’ scores are the same as academic and are greater than applied; (c) for preproverbs concrete and preproverbs abstract, the SSTW scores are not different from the applied scores. The postproverbs concrete and postproverbs abstract scores for the treatment groups also showed no effect of gender but revealed that all students who received the treatment did better on their post scores. The positive changes of the treatment group illustrate a measured movement from literal understanding to abstract understanding using direct Socratic instruction and proverbs as a medium.
    • Metarhizium robertsii interactions with Phaseolus vulgaris (Haricot Bean)

      Hu, Shasha; Department of Biological Sciences
      Metarhizium is an insect pathogenic fungus, as well as a plant root symbiont. During symbiotic interactions, it can benefit the plant by improving plant growth, antagonizing plant pathogens and herbivores, and enhancing plant tolerance to abiotic stresses. In this thesis, the interactions between Metarhizium robertsii and Phaseolus vulgaris (haricot bean) were studied from two aspects. First, a phenotypically degenerated (low conidia production) strain of Metarhizium was serially passaged through bean plant. Second, the immune responses of haricot bean during endophytic colonization were assessed. Commercial application of Metarhizium for insect biocontrol requires optimal production of conidia as infective propagules. It was demonstrated that conidial production and virulence of phenotypically degenerated Metarhizium were restored by serial passages through bean roots, as well as switchgrass roots, and wax moth larvae. A decrease in the expression of fungal DNA methyltransferase was observed in the phenotypically degenerated Metarhizium strain through bean passages. Whole genome bisulfite sequencing analysis showed differences in the distribution of differentially methylated regions in the degenerated and subsequently recovered strains. Metarhizium can antagonize the plant pathogen, Fusarium solani f. sp. phaseoli during bean root colonization. Using comprehensive plant hormone analysis, transcriptional expression, and stomatal size analysis, bean immune responses to colonization by Metarhizium and/or Fusarium were assessed. In comparison to un-inoculated bean, root colonization by Metarhizium resulted in reduction of abscisic acid (ABA), increased stomatal size, and decreased expression of plant immunity genes in bean leaves, which is different from those in bean colonized by Fusarium. Furthermore, exogenous application of ABA resulted in reduction of bean root colonization by Metarhizium but increased colonization by Fusarium, compared to corresponding plants without ABA application. Therefore, ABA was implicated in differential responses of bean plants to root colonization by Metarhizium and Fusarium. In conclusion, this thesis provided new insights into the study of the interactions between Metarhizium and haricot bean. Some novel findings were that fungal DNA methyltransferase was implicated in the recovery of phenotypically degenerated Metarhizium and a plant hormone, abscisic acid was implicated in differential interactions of endophytic colonization by Metarhizium when compared to a pathogenic interaction by Fusarium.
    • METHOXYPYRAZINES AND LADYBUG TAINT IN WINES

      Botezatu, Andreea Ioana; Department of Biological Sciences (Brock University, 2013-11-05)
      Methoxypyrazines are aroma active compounds found in many wine varietals. These compounds can be of either grape-derived nature or can be introduced into wines via Coccinellidae beetles. Regardless of their origin, methoxypyrazines can have either a beneficial role for wine quality, contributing to the specificity of certain wine varietals (Cabernet sauvignon, Cabernet franc, Sauvignon blanc) or a detrimental role, particularly at higher concentrations, resulting in overpowering green, unripe and herbaceous notes. When methoxypyrazines of exogenous nature are responsible for these unpleasant characteristics, wines are considered to be affected by what is generally known as Ladybug taint (LBT). This is work is a collection of studies seeking to create a sensitive analytical method for the detection and quantification of methoxypyrazines in wines; to investigate the role of different Coccinellidae species in the tainting of wines with LBT and identify the main compounds in ladybug tainted wines responsible for the typical green herbaceous characteristics; to determine the human detection threshold of 2,5-dimethyl-3-methoxypyrazine in wines as well as investigate its contribution to the aroma of wines; and finally to survey methoxypyrazine concentrations in a large set of wines from around the world. In the first study, an analytical method for the detection and quantitation of methoxypyrazines in wines was created and validated. The method employs multidimensional Gas Chromatography coupled with Mass Spectrometry to detect four different methoxypyrazines (2,5-dimethyl-3-methoxypyrazine, isobutyl methoxypyrazine, secbutyl methoxypyrazine and isopropyl methoxypyrazines) in wine. The low limits of detection for the compounds of interest, improved separation and isolation capabilities, good validation data, as well as the ease of use recommend this method as a good alternative to the existing analytical methods for methoxypyrazine detection in wine. In the second study the capacity of two Coccinellidae species, found in many wine regions – Harmonia axyridis and Coccinella septempunctata - to taint wines is evaluated. Coccinella septempunctata is shown to be as capable as causing LBT in wines as Harmonia axyridis. Dimethyl methoxypyrazine, previously thought to be of exogenous nature only (from Coccinellidae haemolymph), is also detected in control (untainted) wines. The main odor active compounds in LBT wines are investigated through Aroma Extract Dilution Assay. These compounds are identified as isopropyl methoxypyrazine, sec- and iso- butyl methoxypyrazine. In the third study, the human detection threshold for dimethyl methoxypyrazine in wine is established to be 31 ng/L in the orthonasal modality and 70 ng/L retronasally. After wines spiked with various amounts of dimethyl methoxypyrazine are evaluated sensorally, dimethyl methoxypyrazine causes significant detrimental effects to wine aroma at a concentration of 120 ng/L. The final study examines methoxypyrazine (dimethyl methoxypyrazine, isopropyl methoxypyrazine, secbutyl methoxypyrazine and isobutyl methoxypyrazine) concentrations in 187 wines from around the world. Dimethyl methoxypyrazine is detected in the majority of the red wines tested. Data are interpreted through statistical analyses. A new measure for predicting greenness/herbaceousness in wines - methoxypyrazine “total impact factor” is proposed.