Brock University Digital Repository
Brock University's Digital Repository is an online archive showcasing and preserving the Brock community's scholarly output as well as items from the Library's Archives & Special Collections. Researchers can disseminate their work by depositing it in this Open Access repository, which provides free, immediate access to users while also allowing Brock scholars to track downloads and views of their scholarship. The Digital Repository is also the home of the Brock University E-Thesis Portal.
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Advancing detection, genomics, and secretome analysis of oomycete pathogens Phytophthora capsici and Phytopythium vexans to explore mechanisms of pathogenesis and biocontrol solutions
(Brock University) Villanueva Oscar; Castle Alan; Ellouz Oualid; Department of Biological Sciences
Soilborne oomycete pathogens pose persistent challenges to vegetable production systems, particularly in Ontario, Canada, where Phytophthora capsici and the recently reported Phytopythium vexans have emerged as significant threats. Understanding the molecular mechanisms underlying their pathogenicity is critical for developing informed, site-specific disease management strategies. This thesis integrates comparative genomics, effector biology, and molecular diagnostics to enhance our understanding of their pathogenicity and support effective disease management.
The first component of this work focuses on P. capsici, where whole-genome sequencing of two Canadian isolates (55330 and 55898) revealed compact genomes yet retained a broad array of RxLR and CRN effectors. Comparative analyses with reference strains LT263 and LT1534 v11.0 uncovered both conserved and unique effectors, suggesting that local adaptation may be shaping pathogenic potential in response to regional crop pressures.
Building on this, the second component shifts to P. vexans, a novel strain recently reported in Ontario from apple tree soil. The SS21 P. vexans strain genome was sequenced and compared with the only two openly available strains HF1(China), and (CBS 119.80) (Iran). The genomic analysis reveals similar genome between the Canadian strain SS21 and the reference genomes, additionally SS21 displayed a reduce CAZymes, RxLR and CRN effectors, suggesting a niche adaptation to a specific Canadian agro-ecosystem.
The final component of this thesis focuses on the development of an amplitude-based multiplex droplet digital PCR (ddPCR) assay. Designed for simultaneous quantification of P. capsici, Trichoderma asperellum, and Trichoderma gamsii in soil, this assay was validated in field trials and offers high sensitivity and specificity. The assay displayed a high sensitivity with a limit of detection of 1 pg/µL DNA. The use of multiplex ddPCR offers practical solution for monitoring pathogen and biocontrol populations in complex soil environments.
Advancing detection, genomics, and secretome analysis of oomycete pathogens Phytophthora capsici and Phytopythium vexans to explore mechanisms of pathogenesis and biocontrol solutions
(Brock University) Villanueva Oscar; Castle Alan; Ellouz Oualid; Department of Biological Sciences
Soilborne oomycete pathogens pose persistent challenges to vegetable production systems, particularly in Ontario, Canada, where Phytophthora capsici and the recently reported Phytopythium vexans have emerged as significant threats. Understanding the molecular mechanisms underlying their pathogenicity is critical for developing informed, site-specific disease management strategies. This thesis integrates comparative genomics, effector biology, and molecular diagnostics to enhance our understanding of their pathogenicity and support effective disease management.
The first component of this work focuses on P. capsici, where whole-genome sequencing of two Canadian isolates (55330 and 55898) revealed compact genomes yet retained a broad array of RxLR and CRN effectors. Comparative analyses with reference strains LT263 and LT1534 v11.0 uncovered both conserved and unique effectors, suggesting that local adaptation may be shaping pathogenic potential in response to regional crop pressures.
Building on this, the second component shifts to P. vexans, a novel strain recently reported in Ontario from apple tree soil. The SS21 P. vexans strain genome was sequenced and compared with the only two openly available strains HF1(China), and (CBS 119.80) (Iran). The genomic analysis reveals similar genome between the Canadian strain SS21 and the reference genomes, additionally SS21 displayed a reduce CAZymes, RxLR and CRN effectors, suggesting a niche adaptation to a specific Canadian agro-ecosystem.
The final component of this thesis focuses on the development of an amplitude-based multiplex droplet digital PCR (ddPCR) assay. Designed for simultaneous quantification of P. capsici, Trichoderma asperellum, and Trichoderma gamsii in soil, this assay was validated in field trials and offers high sensitivity and specificity. The assay displayed a high sensitivity with a limit of detection of 1 pg/µL DNA. The use of multiplex ddPCR offers practical solution for monitoring pathogen and biocontrol populations in complex soil environments.
NEW ROUTES IN BIOCATALYSIS: EXPLORING THE IMPACT OF GRAFTING SILICONES ONTO PROTEINS/ENZYMES
(Brock University) Alizadeh, Najibeh; Dr. Paul M. Zelisko; Department of Chemistry
One of the cornerstones of our research is the use of biocatalysis to mitigate the negative impact of chemical processes on the environment. The majority of natural enzymes are highly efficient and can increase the rate of chemical transformations. However, the industrial application of enzymes is often restricted by several limiting factors such as poor operational or long-term stability, especially during exposure to elevated temperatures, organic solvents, and pH extremes. The chemical modification of enzymes using covalent conjugation is a very common stabilization strategy as it imparts stability and protects the enzyme from denaturation. A number of studies have determined that hydrophobic surfaces can have a very positive impact on the reactivity of various enzymes, particularly lipases. The impact of silicones on proteins, mostly through physical/noncovalent interactions has attracted considerable attention recently. Given our research team’s ongoing work in the area of silicone-proteins/enzymes interactions it was of interest to explore the impact of covalently conjugated silicone polymers on proteins.
Herein, a library of hydride-functionalized silicones of differing molecular masses was prepared using the living anionic ring opening polymerization of hexamethylcyclotrisiloxane (D3) to yield poly(dimethylsiloxane) (PDMS) polymers with narrow dispersities (Ð). These polymers were subsequently activated with hydrophilic functional groups including disuccinimidyl carbonate (DSCa) and norbornene dicarboxylate anhydride (NDA) prior to conjugation with proteins/enzymes. Human serum albumin (HSA) was selected as a model protein to study the PDMS/protein chemical interactions prior to the functionalization of enzymes. HSA’s well-documented spectroscopic behaviour as either a native protein or denatured species made it an ideal model to investigate the impact of covalently bonded silicones on proteins. After completion of model protein studies, trypsin and Candida antarctica lipase B (CALB) were modified chemically with functionalized PDMS polymers. The covalent bonding of PDMS polymer chains onto protein/enzyme was studied through matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry. The solubility of the protein/enzyme conjugates were examined in various organic solvents including tetrahydrofuran (THF), chloroform, dichloromethane (DCM), dimethylformamide (DMF), and toluene and confirmed by UV-Vis spectroscopy. The impact of silicones on the protein/enzyme structure was investigated by infrared (IR), circular dichroism (CD), and fluorescence spectroscopy. Thermal behaviour of the protein/enzymes before and after modification with PDMS polymers were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Catalytic function, thermal stability, and the accessibility of active sites of the enzymes of interest after conjugation to the functionalized siloxanes were studied through standard activity assays. This work demonstrates that not only can siloxanes be successfully coupled to proteins, but the bioconjugation also enhances the solubility and activity of enzymes in organic solvents.
Perceptions of Ghanaian Women Regarding Breast Cancer Screening Behavior
(Brock University) Ashorm Faustina; Crawford Joanne; Applied Health Sciences Program
Background: Breast cancer among women is currently the most diagnosed cancer globally, with
an estimated 2.3 million cases recorded in 2020. In Ghana, breast cancer constitutes 31.8% of all
cancers diagnosed in women in 2020 with an incidence rate of 15 to 35 per 100,000. Research into factors that influence engagement of Ghanaian women in breast cancer screening is limited and the existing literature has produced conflicting results. This research aimed to enhance understanding of Ghanaian women’s knowledge, beliefs and attitudes regarding breast cancer.
This study explored Ghanaian women’s perceptions of breast cancer screening behaviour and
provided insights to how breast cancer is perceived and approached within this context. By investigating these perceptions, the study sought to uncover the factors influencing Ghanaian women’s participation in early detection and breast screening.
Methods: In this study, I employed a qualitative research design based on Interpretive Description by Thorne (2016), focusing on women in the mixed rural community of Apra, Ghana. Data were gathered through semi-structured interviews with 14 local women, with an interview guide
informed by constructs from the Health Belief Model (HBM) and the Theory of Planned Behavior. Key constructs, such as perceived barriers, perceived severity, perceived susceptibility, perceived benefits and subjective norms, were explored. Using reflexive thematic analysis, as outlined by Braun and Clarke (2022), the analysis provided in-depth exploration of participants
perceptions, highlighting key themes related to their health beliefs and behaviors.
Findings: The study revealed that Ghanaian women’s perceptions of breast cancer screening are shaped by cultural beliefs, stigma, and limited knowledge. Key themes included the view of the breast as sacred, leading to reluctance in discussing or undergoing screenings, and the fear of
social judgment, with some seeing breast cancer as a moral or spiritual failure. Participants had limited knowledge of breast cancer symptoms but were open to receiving information from
healthcare professionals. Additionally, faith in divine protection influenced some women’s reluctance to seek medical care. These findings highlight the need for culturally sensitive health
education to promote early detection.
Significance and Conclusion: This study contributes to the academic discourse on breast cancer awareness by providing evidence on the perceptions and screening behaviors of Ghanaian women. It highlights the influence of cultural beliefs, social norms, and limited knowledge on early detection practices. The insights gained can inform the development of community-engaged, culturally sensitive health education programs and may guide policies, aimed at
improving breast cancer screening uptake and access to breast health services in mixed rural Ghanaian communities.
Consumer Desires in the Niagara Wine Industry: A Geodemographic Analysis of Customers at a Niagara Winery
(Brock University) Murdoch, Sara; Ripmeester, Michael; Department of Geography
The wine tourism industry is a global industry. Here, the focus will be primarily on winery visitors in the Niagara Region. More specifically, I explore what motivates them to visit wineries and what they hope to experience during their visits. Given significant competition, wineries must cater their expectations to attract visitors to their cellar doors. The purpose of this thesis is to determine whether geodemographic factors (type of community, municipality, general location) in combination with the demographic (age, gender, education, income) factors have an impact on what motivates people to visit wineries and what they expect once they arrive. More precisely, this thesis aims to answer the research question: “Do visitor origin and associated demographics make a difference in motivation to visit a winery and visitor experience expectations?” While doing so, I examine the two sub-themes. First, and as noted above, I seek to explore whether there is there a correlation between expectations for winery experiences and residence of trip origin and other demographic characteristics. Second, I ask “What winery features are visitors hoping to experience?” Using the mailing lists of one small, recently rebranded boutique winery in Jordan Station, Ontario I distributed web-based surveys to collect data on October 3 and 20, 2023. The survey was distributed through two mailing lists (the general mailing list and wine club list to 1568 individuals. A total of 133 individuals responded. Following the data collection process, I used qualitative and quantitative data analysis including coding, cross tabulations, Chi-Square tests, and location analysis though ESRI Community Analyst to explore the data. The analysis did not provide conclusive answers that suggests that location and geodemographic characteristics were significant in determining motivations to visit the winery. The results did, however, allow me to reach the conclusion that visitors are attracted to the experience and social aspects of wineries over
the wine itself. In sum, the data collected can provide valuable information, both practical and academic contributions, on how to cater experiences to a larger audience.