• Novel glutathione disulfide transferase function of CC-glutaredoxins involved in disease resistance and flower development

      Slavickova, Nina; Centre for Biotechnology (Brock University, 2014-08-05)
      Glutaredoxins are oxidoreductases capable of reducing protein disulfide bridges and glutathione mixed disulfides through the process of deglutathionylation and glutathionylation. Lately, redox-mediated modifications of functional cysteine residues of TGA1 and TGA8 transcription factors have been postulated. Namely, GRX480 and ROXY1 glutaredoxins have been previously shown to interact with TGA proteins and have been suggested to regulate redox state of these proteins. TGA1, together with TGA2, is involved in systemic acquired resistance (SAR) establishment in the plant Arabidopsis thaliana through PR1 (Pathogenesis related 1) gene activation. They both form an enhanceosome complex with the NPR1 protein (non-expressor of pathogenesis related gene 1) which leads to PR1 transcription. Although TGA1 is capable of activating PR1 transcription, the ability of the TGA1 NPR1 enhanceosome complex to assembly is based on the redox status of TGA1. We identified GRX480 as a glutathionylating enzyme that catalyzes the TGA1 glutathione disulfide transferase reaction with a Km of around 20μM GSSG (oxidized glutathione). Out of four cysteine residues found within TGA1, C172 and C266 were found to be glutathionylated by this enzyme. We also confirmed TGA1 glutathionylation in vivo and showed that this modification takes place while TGA1 is associated with the PR1 promoter enzymatically via GRX480. Furthermore, we show that glutathionylation via GRX480 abolishes TGA1's interaction with NPR1 and consequently prevents the TGA1-NPR1 transcription activation of PR1. When glutathionylated, TGA1 is recruited to the PR1 promoter and acts as a repressor. Therefore, glutathionylation is a mechanism that prevents TGA1 NPR1 interaction, allowing TGA1 to function as a repressor of PR1 transcription. Surprisingly, GRX480 was not able to deglutathionylate proteins demonstrating the irreversible nature of the reaction. Moreover, we demonstrate that other members of CC-class glutaredoxins, namely ROXY1 and ROXY2, can also catalyze protein glutathionylation. The TGA8 protein was previously shown to interact with NPR1 analogs, BOP1 and BOP2 proteins. However, unlike the case of TGA1 NPR1 interaction, here we demonstrate that TGA8-BOP1 interaction is not redox regulated and that TGA8 glutathionylation by ROXY1 and ROXY2 enzymes does not abolish this interaction in vitro. However, TGA8 glutathionylation results in TGA8 oligomer disassembly into smaller complexes and monomers. Our results suggest that CC-Grxs are unable to reduce mixed disulfides, instead they efficiently catalyze the opposite reaction which distinguishes them from traditional glutaredoxins. Therefore, they should not be classified as glutaredoxins but as protein glutathione disulfide transferases.
    • Novel Magnetic Materials Based on Macrocyclic Ligands: Towards High Relaxivity Contrast Agents and Mononuclear Single-Molecule Magnets

      Stares, Emma; Department of Chemistry
      The preparation and characterization of coordination complexes of Schiff-base and crown ether macrocycles is presented, for application as contrast agents for magnetic resonance imaging, Project 1; and single-molecule magnets (SMMs), Projects 2 and 3. In Project 1, a family of eight Mn(II) and Gd(III) complexes of N3X2 (X = NH, O) and N3O3 Schiff-base macrocycles were synthesized, characterized, and evaluated as potential contrast agents for MRI. In vitro and in vivo (rodent) studies indicate that the studied complexes display efficient contrast behaviour, negligible toxicity, and rapid excretion. In Project 2, DyIII complexes of Schiff-base macrocycles were prepared with a view to developing a new family of mononuclear Ln-SMMs with pseudo-D5h geometries. Each complex displayed slow relaxation of magnetization, with magnetically-derived energy barriers in the range Ueff = 4 – 24 K. In Project 3, coordination complexes of selected later lanthanides with various crown ether ligands were synthesized. Two families of complexes were structurally and magnetically analyzed: ‘axial’ or sandwich-type complexes based on 12-crown-4 and 15-crown-5; and ‘equatorial’ complexes based on 18-crown-6. Magnetic data are supported by ab initio calculations and luminescence measurements. Significantly, the first mononuclear Ln-SMM prepared from a crown ether ligand is described.
    • Novel plant DNA binding protein: Non-expresser of pathogenesis related 1 gene (NPR1) involved in disease resistance

      Pirnia, Saba; Centre for Biotechnology
      For the first time, through validation of the modified Chromatin Immunoprecipitation (ChIP) method (in vitro ChIP), the direct binding of NPR1 to the PR1 promoter was demonstrated. This is a novel advancement on plant systemic acquired resistance (SAR)-mediated disease responses. The NPR1 protein (nonexpressor of pathogenesis related gene 1) is a transcriptional co-activator and positive regulator of SAR, a long-lasting mobile defense signal found in plants. The pathogenesis-Related gene 1 (PR1) is particularly induced during defense response, and as such, is typically used as a marker for establishment of SAR in plants. Salicylic acid (SA) is a phytohormone required for SAR-mediated defense responses against pathogens. Recently, the role of NPR1 as a SA receptor was demonstrated; SA has been shown to directly bind to NPR1 through Cysteine 521 and 529 on the Cterminus region of NPR1 via the transition metal copper. The binding of SA to NPR1 results in disruption of the interaction between BTB/POZ and the C-terminus domains of NPR1. Upon SA-NPR1 binding, the C-terminus transactivation domain is released from the auto-inhibitory BTB/POZ domain, resulting in activation of the NPR1 transcription co-activator function, followed by PR1 transcription in Arabidopsis thaliana. Arabidopsis thaliana has an inducible defense system and is considered a model plant for studying disease resistance responses. In the current research, NPR1 was demonstrated to bind to the PR1 promoter at two distinct regions, in the presence and absence of SA. In the presence of SA, the binding site of NPR1 was determined to be localized at the -636 to -646 base pair sequence; however, in the absence of SA, NPR1 was found to bind around the -790 to -833 base pair sequence. In addition, two distinct DNA binding domains were identified within NPR1, localized on the C and N-terminus regions. In the absence of SA, the DNA binding domain within the N-terminus region, located between amino acids 110-190, was shown to facilitate the binding of NPR1 to the PR1 promoter through the amino acid cysteine 150 (Cys150) via transition metal. The DNA binding domain on the C-terminus region, located between amino acids 513-535, was demonstrated to allow the binding of NPR1 to the promoter of PR1 in the presence of SA. Two amino acids, cysteine 521 and 529 (Cys521/529), were shown to be essential for SA binding to NPR1 and subsequent NPR1 binding to the PR1 promoter. Furthermore, 4hydroxy benzoic acid (4-OH-BA), the inactive analogue of SA, has been demonstrated to be a potent inhibitor of NPR1-PR1 promoter interaction, both in vivo and in vitro, by competing with SA for NPR1 binding. Moreover, we demonstrated that other analogues of the NPR1 protein, NPR2, NPR3, and NPR4, are also recruited to the PR1 promoter. NPR4 showed a similar binding profile to NPR1, both in the presence and absence of SA. NPR2 and NPR3 were observed to only interact with the PR1 promoter in the absence of SA. Both NPR5 and NPR6 were shown to forgo binding to the PR1 promoter, further confirming their role in plant developmental processes other than defense. In addition, the binding of NPR1 to the PR1 promoter was demonstrated to be conserved among other plant species, including rice and maize. Both rice and maize NPR1 proteins were observed to bind to the PR1 promoter in the presence of SA and a metal co-factor, similar to Arabidopsis NPR1. Our results expand our understanding of how NPR1 interacts with the PR1 promoter to regulate gene expression during SAR establishment. This study also revealed that NPR1-mediated SAR defense signaling is conserved among other crop species, which can potentially facilitate the identification of novel plant-priming compounds through high-throughput chemical screening procedures alongside the application of the validated in vitro ChIP technique as a primary screening method.
    • Novel ways to measure future-oriented cognition: Using parent-report measures and open-ended responses to explore young children’s future thinking development

      Mazachowsky, Tessa; Department of Psychology
      Future-oriented cognition encompasses a set of key abilities that children must develop for successful functioning in daily life including, saving, prospective memory, episodic foresight, planning, and delay of gratification. These future thinking abilities are supported by memory systems (e.g., semantic, episodic), as well as constructive processes, self-projection, and executive functions. Research primarily measures young children’s future-oriented abilities through behavioural tasks, which have various limitations and may not engage future thinking. The current studies introduce new methods to overcome some of these limitations: developing a parent-report questionnaire and examining children’s open-ended responses. In Study 1 (N = 101; Mazachowsky & Mahy, 2020), 3-to 7-year-old’s future thinking was examined to establish the psychometric properties of a new parent-report measure, The Children’s Future Thinking Questionnaire (CFTQ). The CFTQ detected development of children’s future thinking and is a reliable and valid measure. Study 2 (N = 48; Mazachowsky et al., 2020) examined 3-to 5-year-old children’s episodic foresight using a novel, open-ended version of the Picture-book task. Results showed that children were able to generate items for future use and were more successful with age. Children’s explanations for their generated items were typically present-focused and included both episodic and semantic details. Expanding on Study 2, Study 3 (N = 158; Mazachowsky et al., revisions requested) explored 3-to 5-year-old’s explanations for their item choices on two episodic foresight tasks to determine the degree to which these tasks engaged children’s episodic and future-oriented processes. Children provided more future-oriented explanations on the Picture-book task compared to the Spoon task, but episodicity did not differ between tasks. Further, children’s Picture-book task explanations included more first-person personal pronouns compared to the Spoon task, but explanations did not differ in other pronoun use. Together, these studies show that use of a parent-report measure and examination of children’s open-ended responses offer unique insight into the development of young children’s future thinking and engagement in future-oriented processes.
    • Novices' learning from the Internet : an exploration of navigation behaviours, learner-related factors, and mental effort

      Desjarlais, Malinda; Department of Psychology (Brock University, 2011-03-08)
      The current study was an exploration of why some novices are more successful than their peers when learning from the Internet by examining the relations among time spent with relevant information and changes in invested mental effort during Internet navigations as well as achievement. Navigation behaviours and learner characteristics were investigated as predictors of time spent with relevant information and changes in mental effort. Undergraduates (N = 85, Mage = 20 years, 5 months) searched the Internet for information corresponding to a low knowledge topic for 20 min while their eye gaze and pupil size were recorded. Pupil diameter was used as an objective, continuous measure of mental effort. Participants also completed questionnaires or computer tasks pertaining to s e l f-regulated learning characteristics (general intrinsic goal orientation and effort regulation) and cognitive factors (working memory control, distractibility and cognitive style). All analyses controlled for general mental ability, reading comprehension, topic and Internet knowledge, and overall motivation. A greater proportion of time spent with relevant information predicted higher scores on an achievement test. Interestingly, time spent with relevant information partially mediated the positive relation between the frequency of increases in invested mental effort and achievement. Surprisingly, intrinsic goal orientation was negatively related to time spent with relevant information and effort regulation was negatively related to the frequency of increases in invested mental effort. These findings have implications for supports when novices guide their own learning, especially when using the Internet.
    • De novo sequencing, annotation, and characterization of the genome of Lavandula angustifolia (Lavender)

      Nattamai Malli Pooranachandhiran, Radesh; Centre for Biotechnology
      Lavender (Lavandula angustifolia) is a perennial plant native to the Mediterranean region, best known for its essential oil (EOs) that have numerous applications in the pharmaceutical, cosmetic and perfume industries. We performed sequencing of the L. angustifolia genome and report a detailed analysis of the assembled genome, focusing on genome size, ploidy, and repeat content. The lavender genome was estimated to be around 870 Mbp (1C=0.96 pg) using a quantitative PCR method. Genome size was further validated through analysis of raw genome sequences using Kmergenie, providing a conclusive end to the lavender genome size dispute. The repeat element composition of the genome was analyzed using de novo (RepeatModeler) and library-based methods (RepeatMasker) and was estimated to be around 45% of the full genome or ~57% of the non-gap genome sequences. Further characterization revealed Long Terminal Repeat (LTRs) retrotransposons as the major repeat type, which contribute to ~18% of the genome, followed by DNA transposons at ~8.5% of the genome. Interestingly, unlike most other plant genomes, the lavender genome has many more Copia than Gypsy elements, both showing a trend of recent increasing activity. Furthermore, these LTRs, especially Copia elements, have shown active participation in gene function including genes for essential oil production, with Copia elements contributing to ~30 % of the coding DNA sequence (CDS) regions, in addition to promoter, intron and untranslated (UTR) regions. The lavender genome also has an unusually high number of miniature inverted-repeat transposable elements (MITEs) compared to other model plant genomes, with the number being ~88,000, which is close to that (~90,000) of the much larger maize genome. Analysis also revealed the lavender genome with a high proportion at polyploidy level, which is strongly biased towards regions containing essential oil genes, with polyploidization events in the lavender genome occurred between 16 to 41 Mya. In conclusion, our results reveal the lavender genome to be highly duplicated and with past and ongoing active retrotransposition, making the genome optimized for EO production.
    • Ojibwe Elders' Experiences of Peace: To Teach Our Well-Being With the Earth

      Lafleur, Gail Sarah; Department of Graduate and Undergraduate Studies in Education (Brock University, 2013-11-15)
      This research focuses on exploring the Anishinaabek/Ojibwe worldview founded upon the spiritual relationship with Mother Earth as the Anishinaabek view of peace to teach our well-being with earth. This research explores the experiences of four 21st century traditional Anishinaabek elders through describing their ways of knowing and of being as it relates to the Anishinaabek worldview of respect and peace with nature. This respect for Mother Earth and respecting earth’s way−akii-bimaadizi is articulated and shared regarding elders’ experiences of teaching our well-being with earth−Akinomaage mino akii-ayaa and is based upon Anishinaabek spirituality. This research details the Anishinaabek worldview from the elders’ shared experiences of earth as teacher and elder. Ten themes emerged from the data. These themes included (a) going back to our original gifts and instructions/building your sacred bundle/sharing your sacred bundle, (b) wisdom−nbwaakaawin: connecting the dots/original instructions/medicine−mshkiki/environmental consciousness, (c) sacred teachings/learning from the elders, (d) relationships/honoring elders/eldership, (e) political experiences and awareness, (f) a way of being in Anishinaabek research, (g) survival, (h) peace is our worldview demonstrated, (i) be aware of colonialistic thinking, (j) Akinomaage: earth as context. The researcher also shares her reflections as a researcher and as an Anishinaabekwe: Ojibwe woman.
    • On the Ball Implementation of Canada Basketball’s Athlete Development Model

      Whitaker-Campbell, Tammy; Applied Health Sciences Program
      The purpose of this dissertation was to explore the perceived benefits and challenges of Canada Basketball’s athlete development model (ADM)/long-term athlete development (LTAD) by administrators, learning facilitators, and coaches at Canada Basketball to better understand the barriers to and enablers of this process. The methodological approach used for the study was an exploratory case study. Methods were established that were consistent with the iterative nature of case study. In total, 5 participants who identified as administrator/learning facilitator/coach, 6 participants who identified as /learning facilitator/coach, and 1 participant who identified as a coach participated in the study. In-depth semi-structured interviews were conducted with each participant that provided new insight into participants’ perceptions of and experiences with ADM/LTAD relative to their positions. Analysis revealed themes related to perceived (a) benefits while using ADM/LTAD; and (b) and challenges with using ADM/LTAD. These findings provide a preliminary assessment of one sport specific athlete development model and may inform research of other sport-specific athlete development programs. Several implications of the study findings are discussed and suggestions are posed for future research.
    • Opening a can of worms : perceptions and practices of teachers in Newfoundland and Labrador incorporating the role of a therapist

      Maich, Kimberly.; Department of Graduate and Undergraduate Studies in Education (Brock University, 2009-05-28)
      Educational trends of inclusion and collaboration have led to changing roles of teachers, including an emphasis on personal support. To provide for social, emotional, and behavioural needs, teachers may adopt a therapeutic role. Many models for such support are proposed, with most models including the importance of student-teacher relationships, a focus on social, emotional, and behavioural development, and direct instruction of related skills. This study includes 20 interview participants. In addition, 4 of the 20 interview participants also took part in a case study. It examines whether participants adopt a therapeutic role, their beliefs about student-teacher relationships, whether they provide interventions in personal issues, and instructed social, emotional, and behaviour skills. Findings show that teachers adopt an academic role as well as a therapeutic role, believe student-teacher relationships are important, are approached about personal issues, and instruct social, emotional, and behavioural skills. Talking and listening are commonly used to provide support, typically exclusive of formal curricular goals. The challenges in providing front-line support issues that may be shared within an established student-teacher relationship are considered. Support in turn for teachers who choose to provide support for personal issues in the classroom within a therapeutic role are suggested, including recommendations for support and referral related to specific social, emotional, or behavioural scenarios that may arise in the school community.
    • Opening truth to imagination : the pragmatism of John Dewey and Richard Rorty

      McClelland, Kenneth A.; Department of Graduate and Undergraduate Studies in Education (Brock University, 2006-05-28)
      This study explores in a comparative way the works of two American pragmatist philosophers-John Dewey and Richard Rorty. I have provided a reading of their broader works in order to offer what I hope is a successful sympathetic comparison where very few exist. Dewey is often viewed as the central hero in the classical American pragmatic tradition, while Rorty, a contemporary pragmatist, is viewed as some sort of postmodern villain. I show that the different approaches by the two philosophers-Dewey's experiential focus versus Rorty's linguistic focus-exist along a common pragmatic continuum, and that much of the critical scholarship that pits the two pragmatists against each other has actually created an unwarranted dualism between experience and language. I accomplish this task by following the critical movement by each of the pragmatists through their respective reworking of traditional absolutist truth conceptions toward a more aesthetical, imaginative position. I also show how this shift or "turning" represents an important aspect of the American philosophical tradition-its aesthetic axis. I finally indicate a role for liberal education (focusing on higher nonvocational education) in accommodating this turning, a turning that in the end is necessitated by democracy's future trajectory

      Frampton, Mark B.; Centre for Biotechnology (Brock University, 2013-02-22)
      The first part of this thesis studied the capacity of amino acids and enzymes to catalyze the hydrolysis and condensation of tetraethoxysilane and phenyltrimethoxysilane. Selected amino acids were shown to accelerate the hydrolysis and condensation of tetraethoxysilane under ambient temperature, pressure and at neutral pH (pH 7±0.02). The nature of the side chain of the amino acid was important in promoting hydrolysis and condensation. Several proteases were shown to have a capacity to hydrolyze tri- and tet-ra- alkoxysilanes under the same mild reaction conditions. The second part of this thesis employed an immobilized Candida antarctica lipase B (Novozym-435, N435) to produce siloxane-containing polyesters, polyamides, and polyester amides under solvent-free conditions. Enzymatic activity was shown to be temperature dependent, increasing until enzyme denaturation became the dominant pro-cess, which typically occurred between 120-130ᵒC. The residual activity of N435 was, on average, greater than 90%, when used in the synthesis of disiloxane-containing polyesters, regardless of the polymerization temperature except at the very highest temperatures, 140-150ᵒC. A study of the thermal tolerance of N435 determined that, over ten reaction cycles, there was a decrease in the initial rate of polymerization with each consecutive use of the catalyst. No change in the degree of monomer conversion after a 24 hour reaction cycle was found.
    • The osmoadaptive response of the wine yeast Saccharomyces cerevisiae K1-V1116 during icewine fermentation

      Martin, Stephanie J.; Centre for Biotechnology (Brock University, 2008-05-28)
      The adapted metabolic response of commercial wine yeast under prolonged exposure to concentrated solutes present in Icewine juice is not fully understood. Presently, there is no information regarding the transcriptomic changes in gene expression associated with the adaptive stress response ofwine yeast during Icewine fermentation compared to table wine fermentation. To understand how and why wine yeast respond differently at the genomic level and ultimately at the metabolic level during Icewine fermentation, the focus ofthis project was to identify and compare these differences in the wine yeast Saccharomyces cerevisiae KI-Vll16 using cDNA microarray technology during the first five days of fermentation. Significant differences in yeast gene expression patterns between fermentation conditions were correlated to differences in nutrient utilization and metabolite production. Sugar consumption, nitrogen usage and metabolite levels were measured using enzyme assays and HPLC. Also, a small subset of differentially expressed genes was verified using Northern analysis. The high osmotic stress experienced by wine yeast throughout Icewine fermentation elicited changes in cell growth and metabolism correlating to several fermentation difficulties, including reduced biomass accumulation and fermentation rate. Genes associated with carbohydrate and nitrogen transport and metabolism were expressed at lower levels in Icewine juice fermenting cells compared to dilute juice fermenting cells. Osmotic stress, not nutrient availability during Icewine fermentation appears to impede sugar and nitrogen utilization. Previous studies have established that glycerol and acetic acid production are increased in yeast during Icewine fermentation. A gene encoding for a glycerollW symporter (STL1) was found to be highly expressed up to 25-fold in the i Icewine juice condition using microarray and Northern analysis. Active glycerol transport by yeast under hyperosmotic conditions to increase cytosolic glycerol concentration may contribute to reduced cell growth observed in the Icewine juice condition. Additionally, genes encoding for two acetyl CoA synthetase isoforms (ACSl and ACS2) were found to be highly expressed, 19- and II-fold respectively, in dilute juice fermenting cells relative to the Icewine juice condition. Therefore, decreased conversion of acetate to acetyl-CoA may contribute to increased acetic acid production during Icewine fermentation. These results further help to explain the response of wine yeast as they adapt to Icewine juice fermentation. ii
    • Part Time University Teaching in Ontario: A Self-Study

      Cope Watson, Georgann; Department of Graduate and Undergraduate Studies in Education (Brock University, 2013-09-06)
      This qualitative self-study explored the disappointment I felt as a part-time university teacher in a mid-sized, primarily undergraduate Ontario university, where I experienced difficulty integrating my beliefs about teaching into my practice of teaching. The purpose of this qualitative study was to inquire into why it was difficult for me, representative of a part-time university teacher in a mid-sized, primarily undergraduate university, to enact the critical pedagogical practices I espoused in my teaching philosophy. The secondary purpose was to apply the findings of the study to reframe my university teaching practice in a way that met my need to enact my beliefs about university teaching while complying with the broader geo-political conditions of part-time university teaching in Ontario (Loughran, 2006; Russell & Loughran, 2007). This study is grounded in the sociological theoretical framework of critical pedagogy (Freire, 1970; Giroux, 1988, 2010; McLaren, 2003) and the methodological framework of The Self-Study of Teacher Education Practices (S-STEP). This study combined the methods of Brookfield’s (1995; 2002) critically reflective practice and Cole and Knowles (2000) practice of reflexive inquiry with Creswell’s (2005) methods of thematic analysis to answer the research question: Why is it difficult for me to enact my beliefs about university teaching as a part-time teacher in an Ontario university? Findings suggest the geo-political contexts of part-time university teaching work can impact a teacher’s ability to enact his/her beliefs about teaching within his/her practice of teaching.
    • Partnership for arts integration : exploring the experiences of teachers and artists working with integrated arts programs

      Attenborough, Debra.; Department of Graduate and Undergraduate Studies in Education (Brock University, 2008-05-28)
      This research acknowledges the difficulties experienced by teachers presenting integrated arts curricula. Instructional support is offered by arts organizations that provide arts partnerships with local schools boards. The study focuses on the experiences of 8 teachers from a Catholic school board in southern Ontario who participated in integrated arts programs offered by The Royal Conservatory of Music's Learning Through the Arts™ (LTTATM) program and a local art gallery's Art Based Integrated Learning (ABIL) program and examines their responses to the programs and their perception of personal and professional development through this association. Additionally, questions were posed to the . "aftisfs"from-tneSe]Jfograrrrs;-and"they liiscus·sed·how"participating in-collaboration with teachers in the development of in-school programs enabled them to experience personal and professional development as well. Seven themes emerged from the data. These themes included: teachers' feelings of a lack of preparedness to teach the arts; the value of the arts and arts partnerships in schools; the role of the artists in the education of teachers; professional development for both teachers and artists; the development of collegiality; perceptions of student engagement; and the benefits and obstacles of integrating the arts into the curriculum. This document highlights the benefits to both teachers and artists of arts partnerships between schools and outside arts organizations.
    • Patterns of Endocrine, Behavioural, and Neural Function Underlying Social Deficits after Social Instability Stress in Adolescent Rats

      Hodges, Travis; Department of Psychology
      Adolescence is a time of social learning as well as a period of heightened vulnerability to stressors and enhanced plasticity, compared with adulthood. Previous research found that repeated social instability stress (SS; daily isolation and return to an unfamiliar peer from postnatal day (PND) 30 - 45) administered in adolescent rats alters social function when tested in adulthood. The main goal of my thesis research was to characterize how SS in adolescent rats affects the development of social brain regions and social behaviour when tested soon after the procedure. In chapter 2, I found that SS potentiated corticosterone release in rats repeatedly paired with an unfamiliar cage-mate after isolation compared with rats that were paired with an unfamiliar cage-mate for the first time after isolation on PND 45. In chapter 3, I found that in social interaction tests (i.e., not in home cage), SS rats had lower social interactions despite having higher social approach with unfamiliar peers relative to control (CTL) rats. Social stimuli carried the same reward value for SS and CTL rats based on tests of conditioned place preference, and SS in adolescence impaired social recognition. Further, SS increased oxytocin receptor density in the nucleus accumbens and dorsal lateral septum in rats compared with CTL rats. In chapter 4, I found that the correlations between time spent in social interaction with an unfamiliar peer and Fos immunoreactivity (a marker of neural activity) in the arcuate nucleus, dorsal lateral septum, and posterior medial amygdala were in the opposite direction in SS rats to those in CTL rats. In chapter 5, I found differences in the expression of proteins relevant for synaptic plasticity and in dendritic arborisation in the lateral septum and medial amygdala. My findings of behavioural and neural differences between SS and CTL rats highlight the heightened vulnerability of the brain to the quality of social experiences during the adolescent period that may lead to long-lasting deficits in social function in adulthood.
    • Perceptions of Adolescent Males and Their Parents as to Factors That Influence the Young Men's Academic Performance

      Tierney, Patrick J.; Department of Graduate and Undergraduate Studies in Education (Brock University, 2014-12-10)
      Postsecondary enrolments of young males has been declining since the mid-1980s. The decline can be attributed, at least in part, to boys and young men being unable to compete for a fixed number of available places in institutions of higher learning, whether in community college or university. This inability to compete stems from their academic performance in secondary school. This study interviewed adolescent males and their parents as to their perceptions of a number of factors that may contribute to their academic performance. Those factors included noncognitive skills, dimensions of character, perceptions of teachers, general attitudes towards school, and likes and dislikes on a range of course subjects. One of the most important findings was that only one of the seven adolescent male participants was considering a future career that would require a university degree. Other findings showed the young men's noncognitive skills were weak, particularly in relation to time management skills and their unwillingness to ask for help with schoolwork and homework. Most of the young men expressed a dislike for mathematics beyond high school, a subject key to the study, of the natural sciences, engineering, technology, and business. Recommendations include school reforms both inside the classroom and beyond. Additionally, a framework using project management theory and practice has been proposed to improve noncognitive skills, dimensions of character, and executive function.
    • Perceptions of Change in Self-Efficacy to Pursue Postsecondary Education for Students with Exceptionalities Participating in a Postsecondary Transition Program

      Ismailos, Linda; Department of Graduate and Undergraduate Studies in Education
      This mixed-methods study explored a postsecondary transition program’s effect on the development of self-efficacy for post-secondary studies and the likelihood to apply to post-secondary studies among students with exceptionalities. The study also examined how their perceptions of change in self-efficacy compared to their non-exceptional peers in the program. Participants included Grade 11 and 12 students with and without exceptionalities who were at risk of non-completion of their secondary school diploma from 2 participating boards of education at a college in Ontario, Canada. Students participated in a series of pre- and post-program completion surveys and were further invited to participate in a personal follow-up interview to explore the impact of their experience in the program on their plans for postsecondary education. Secondary school teachers working in a supportive role with students in this program were also interviewed to explore their perceptions of change in the students over the duration of the program. Findings demonstrated that students both with and without exceptionalities benefitted from the program through a number of elements that resulted in increased self-efficacy to succeed in postsecondary education, and an increased likelihood to apply to a postsecondary program in the future. Findings, however, indicated that the two groups of students did not share the same perceptions of how the program might have contributed to their increased self-efficacy. Following program completion, students with exceptionalities were more likely to describe their personal mastery experiences in a postsecondary academic program and their process of metacognitive skill development, whereas their peers without exceptionalities were more likely to describe a positive experience on a college campus as the primary contributing factor for their increased academic self-efficacy. The study further discusses the elements that contributed to the change experienced by the students with exceptionalities and offers a visual framework for the elements involved in the development of academic self-efficacy for students with exceptionalities. Interpretations and suggestions as to how these insights could inform future policy and practice are discussed.
    • Phage-mediated biological control of Erwinia amylovora: The role of CRISPRs and exopolysaccharide

      Yagubi, Abdelbaset; Department of Biological Sciences
      Fire blight, caused by bacterium Erwinia amylovora, is a very serious disease affecting apple, pear and other fruit plants. The development of phage-based biopesticides is currently in progress in our lab. Emergence of phage-resistant bacteria is a valid concern. Two attributes of the bacterial host that may contribute to the development of resistance were studied, the Clustered Regularly Interspaced Short Palindromic Repeats/ CRISPR-associated (CRISPR/Cas) system and exopolysaccharide (EPS) interaction with phages. The structure of E. amylovora CRISPR/Cas system was determined in 8 E. amylovora isolates from different geographical regions. Three CRISPR-array sets named CR1, CR2 and CR3 were detected in 4 isolates, and only 2 arrays were determined in the rest of the isolates. No significant similarity was found between spacers in any of these systems to phage DNA sequenced in this study or from GenBank. Also the Cas level of expression was not stimulated during phage infection. Introduction of extra copies of Cas genes to enhance expression did not result in phage resistance. Nevertheless, E. amylovora CRISPR/Cas system was found to be efficient in blocking the transformation of plasmids carrying protospacers matched spacers in CRR1 and CRR2. Among phages that have been sequenced in this study are ΦEa9-2 and ΦEa35-70. ΦEa9-2 (Podoviridae) genome is 75,568 bp, and found to be related to coliphage N4. ΦEa35-70 (Myoviridae) genome is 271,084 bp, and found to carry a potential EPS depolymerase gene. Activity of ΦEa35-70 EPS depolymerase was only detected when cloned and expressed in E. coli, but His-tagged purified protein did not exhibit any EPS-depolymerase activities. This study offers critical information for the design of novel and effective phage-based biopesticides for the control of E. amylovora. It provides a new knowledge on the molecular structure and function of CRISPR/Cas system and EPS-phage interaction.
    • Physical Activity and Fitness in Children with Developmental Disorder

      Rivilis, Irina; Applied Health Sciences Program (Brock University, 2012-05-17)
      Introduction: Developmental coordination disorder (DCD) is a prevalent condition characterized by poor motor proficiency that interferes with a child‟s activities of daily living. Children with DCD often experience compromised health-related fitness components such as cardiorespiratory fitness (CRF). Purpose: To better understand the physical activity and fitness characteristics of children with probable DCD (pDCD), with a particular focus on CRF. Specifically: (1) to present a synopsis of current literature; (2) to determine the longitudinal trajectories of CRF; (3) to compare the submaximal CRF of children with and without pDCD. Methods: A comprehensive, systematic literature review was conducted of the recent available data on fitness and physical activity and pDCD (Chapter 2). This review provided the background for the other two studies included in this thesis. In Chapter 3, a prospective cohort design was used to assess how CRF in children with pDCD changes over time (56 months) relative to a group of typically developing controls. Using a nested-case control design, 63 subjects with pDCD and 63 matched controls from the larger sample were recruited to participate in the lab-based component of the study (Chapter 4). In this investigation CRF was examined using the oxygen cost of work (VO2) during an incremental test on a cycle ergometer. Results: The literature review showed that fitness parameters, including CRF and physical activity levels, were consistently reduced in children with pDCD. Chapter 3 demonstrated that the difference in CRF between children with pDCD and typically developing children is substantial, and that it tends to increase over time. Results from VO2 assessments showed that children with pDCD utilized more oxygen to sustain the same submaximal workloads compared to typically developing children. Conclusions: Findings from this thesis have made several important contributions to our understanding of children with pDCD. Since differences in CRF between children with and without pDCD tend to worsen over time, this adds to the argument that interventions intended to improve CRF may be appropriate for children with motor difficulties. This thesis also presented the first evidence suggesting that DCD involves higher energy expenditure, and could help explain why children with pDCD perform poorly on tasks requiring CRF.
    • Physical Correlates of Sexual Orientation: The Association of Height, Birth Weight, and Facial Structure with Sexual Orientation.

      Skorska, Malvina N.; Department of Psychology
      Researchers have examined whether certain physical characteristics are associated with sexual orientation to gain insight into the mechanisms that may be implicated in its development. Three relatively new and/or understudied physical correlates (height, birth weight, facial structure) were investigated to determine whether they are reliably associated with sexual orientation and to gain insight into the specific mechanism(s) that may be driving the association between these physical correlates and sexual orientation. In Study 1, gay men were found to be shorter, on average, than heterosexual men in a nationally representative US sample. There was no significant height difference between lesbian and heterosexual women. No evidence was found that stress and nutrition at puberty mediated the association between sexual orientation and height in men. Thus, other mechanisms (e.g., prenatal hormones, genetics) likely explain the sexual orientation-height link. In Study 2, firstborn gay male only-children had, on average, a significantly lower mean birth weight than firstborn children in four other sibship groups. There was also evidence of increased fetal loss among mothers of gay male only-children. Birth weight and fetal loss have been shown to be indicators of a mother’s immune system responding to a pregnancy. Thus, Study 2 provides support for the idea that a maternal immune response (and one that appears to be distinct from the maternal immune response hypothesized to explain the traditional fraternal birth order effect) is implicated in sexual orientation development. In Study 3, lesbian and heterosexual women differed in 17 facial features (out of 63) at the univariate level, and four were unique multivariate predictors. Gay and heterosexual men differed in 11 facial features at the univariate level, and three were unique multivariate predictors. Some of the facial features related to sexual orientation implicated a sexual differentiation related mechanism (e.g., prenatal hormones), whereas others implicated a non-sexual differentiation mechanism (e.g., developmental instability) to explain the sexual orientation-facial structure association. In addition to extending the empirical literature on the physical correlates associated with sexual orientation, the studies included in this dissertation extend our understanding of the various mechanisms likely implicated in the development of sexual orientation.