Abidi , Noureddine2022-04-052022-04-052017-122017-11-27December 2https://hdl.handle.net/2346/88936Fourier Transformed Infrared microspectroscopy (FTIR) Imaging is a reliable tool to investigate biochemical changes in biological samples. The FTIR image is composed of a grid of infrared spectra, where each pixel has an individual spectrum that reveals the chemical composition of a given pixel. Each vibration in an IR spectrum is assigned to a chemical functional group. The location, intensity, and shape of IR vibrations provide information regarding the concentration, the molecular structure, and the chain conformation of biomolecules present in biological samples. The functional group distribution maps can be used for spatial characterization of different chemical functional groups without sample staining. Although the FTIR imaging has been increasingly used for analyzing biological tissues, the main application has been shifted towards cancer investigations. Only limited studies were reported on FTIR imaging of plant cells and tissues. In this study, a diverse range of biological tissues was analyzed using FTIR imaging to explore the potential uses of FTIR imaging. The FTIR images can produce inaccurate results due to several reasons (ex. sample contaminations and uneven sample thickness). Therefore, sample preparation, data collection, and analysis were optimized for each study. First, the biochemical composition of individual plant cells was investigated using onion epidermal cells as model plant cells. The compositional variability within individual onion tissues and between immature and mature onion cells were identified. Second, the distribution of cellulose in individual cotton fibers at different phases of fiber maturity, and the continuous biochemical changes associated with fiber development in individual cotton fibers were investigated. Next, cryo-sectioning of different mouse tissues was optimized, and high-fat diet induced biochemical changes in liver and adipose tissues (brown and white adipose tissues), harvested from mice fed either a low-fat or a high-fat diet, were investigated. Future target of this study is to investigate the beneficial effects of different plant extracts, such as dietary fibers (ex. guar gum), antioxidants (ex. grape), and polyunsaturated fatty acids (ex. olive oil), to reduce obesity-associated metabolic disorders. Although, the study of induced changes in biomolecules of biological samples, in plants and animals is not a simple task, cryosectioning followed by FTIR imaging could provide new insight to understand those changes.application/pdfFTIR imaging, Onion tissues, Plant cells, Cotton fibers, Cryosectioning, Optimization, Obesity, Adipose tissues, Non-alcoholic fatty liver disease, Biomedical tissuesThesis2022-04-05