Saudi Cultural Missions Theses & Dissertations
Permanent URI for this communityhttps://drepo.sdl.edu.sa/handle/20.500.14154/10
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Item Restricted Investigating low-dose UV-C radiation stress for improved cultivation of microalgae for biofuel and bio- products(Saudi Digital Library, 2023-11-14) Tanko, Wesal; Pittman, JonThe use of food crops for biofuel production has led to concerns about agricultural productivity and global food supply, creating a "food vs fuel" dilemma. Microalgae have emerged as a potential alternative feedstock for biofuels, but commercial viability remains a challenge. To address this, alternative methods are needed to induce metabolic modifications in microalgae without compromising biomass yield. This study investigates the effects of non-lethal, low doses of ultraviolet C (UV-C) radiation as a potential stressor for metabolic modifications in microalgae. The objective was to quantify the physiological and metabolic effects of UV-C exposure, focusing on understanding its impact rather than generating mutants. Exposure of the biflagellate green microalgae Chlamydomonas reinhardtii and Dunaliella salina to low doses of UV- C (500, 1000 or 2000 μJ/cm2) was followed by 24 h incubation in either light/dark cycle conditions or in full darkness. In addition, a single round of UV-C exposure was compared with three rounds of exposure. The main findings from the study were that repetitive exposure to UV-C stimulated lipid accumulation in irradiated C. reinhardtii and this increased significantly up to 3-fold with the increase in UV-C dose. This was concluded to be a stress response since the highest UV-C doses decreased cell growth and viability, inhibited photosynthetic activity, and increased reactive oxygen species (ROS) production. UV-C exposure also increased cell sedimentation up to 90% that was likely due to flagella detachment and loss of motility. Furthermore, the 24 h period of dark after the UV-C exposure enhanced the stress response to the radiation but also negatively affected the non-irradiated control cells. Compared to C. reinhardtii, D. salina was found to be more tolerant to the UV-C radiation. This was proposed to be due in part to increased antioxidant activity in the salt tolerant and carotenoid-accumulating D. salina which showed a strong negative correlation between β-carotene concentration and ROS abundance. The increase in β-carotene was approximately 2-fold under the highest salt concentration NaCl of 1.2 M. Finally, a transcriptomic analysis found that UV-C exposure and/or 24 h dark incubation caused substantial changes in gene expression in C. reinhardtii. This included up-regulation of protective mechanisms such as heat shock proteins, and genes related to photosynthesis, down-regulation of genes associated with flagella function, and a complex response for genes related to starch and lipid metabolism, with many genes down-regulated but also many up-regulated. In conclusion, low dose UV-C stimulation of lipid, starch and antioxidants could potentially become an important tool for enhancing microalgae production in the future.30 0Item Restricted OVERCOMING CONTEMPORARY CHALLENGES IN KIDNEY DISEASE TREATMENT THROUGH METABOLOMIC AND DATA SCIENCE APPROACHES(Monther Alsultan, 2023-04-05) Alsultan, Monther; Wijesinghe, Dayanjan SEarly identification and therapy are essential for preventing the worsening of kidney function. However, the lack of predictive, noninvasive biomarkers has posed a challenge in the diagnosis and management of this prevalent condition. Furthermore, there are barriers to effective treatment that limit our capacity to provide improved health management for individuals with kidney failure. The main objectives are to: Identify the challenges of current biomarkers in kidney disease and propose a metabolomic approach to overcome them by investigating metabolomic alterations associated with the etiology of renal disease, and discuss barriers to optimal care in CKD and discusses the role of data science in improving healthcare. To explore biomarkers and etiology of kidney dysfunction, untargeted lipidomic analysis was performed from a prospective observational cohort of adult kidney transplant patients. To overcome the barriers to optimal care in CKD, an open-source programming language was used to develop and implement an anticoagulant agents platform. Our lipidomic study of kidney transplant patients identified lipid predictors of kidney rejection. This study’ findings show that the lipidome may be used to predict graft function in kidney transplant recipients. A clinical decision support application was developed to provide anticoagulation management guidance. It provides tools for calculating warfarin dosing, and providing anticoagulation methods for individuals with renal impairment. This dissertation also illustrates that lipidomic biomarkers have the potential to provide valuable insights into the health status of patients. Further research is needed to strengthen our lipid biomarker findings and to validate our decision-making tool in real-world practice.12 0