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Title Μελέτη δομικών αλλαγών λόγω γήρανσης στους ραβδωτούς μυς του μοντέλου οργανισμού Caenorhabditis elegans μέσω μετρήσεων δεύτερης αρμονικής ευαίσθητης στην πόλωση (PSHG)
Alternative Title Monitoring structural modifications in striated muscles of Caenorhabditis elegans samples, due to aging, via PSHG measurements
Author Γιουρούκου, Κωνσταντίνα
Thesis advisor Χαραλαμπίδης, Δημήτριος
Reviewer Φιλιππίδης, Γιώργος
Τσαφάς, Βασίλης
Abstract The target of this thesis is to investigate myosin structural modifications due to aging through Polarization sensitive Second Harmonic Generation (PSHG) imaging microscopy measurements. Second Harmonic Generation (SHG) is a non-linear scattering phenomenon, which means that the energy isn't absorbed from the sample making this imaging technique ideal for in-vivo observation in biological samples. Advantages of SHG include the high resolution (approximately 0.5μm) which gives the ability for observation at a cellular level, the increased penetration depth of the beam into the tissue (up to 500μm), and the capability for 3D spatial analysis. Also, SHG records label-free images minimizing photobleaching and phototoxicity effects on the biological specimens. Exploiting the sensitivity of SHG signal to the polarization of the incident radiation wave, we extract significant quantitative information from the samples. In our study, this information is contributed to the investigation and monitoring of structural changes that occur in myosin molecules due to aging. The biological samples that we used in this survey were the model organisms Caenorhabditis Elegans (C. Elegans). We focused on the part of the worm where the striated muscles are located. According to previous studies, the intensity of SHG was described by a mathematical model which was based on the cylindrical symmetry that the myosin molecules are formulated with the major symmetry axis of the muscle fiber. In this project, the use of FFT (Fast Fourier Transform) algorithm for the SHG signal analysis shows that the myosin molecules are better described from a general mathematical model. Our experimental results demonstrate that the older biological samples present an increased need to be described from the general mathematical model than the younger ones. This fact indicates that the myosin molecules' structure is changed over time. These results are encouraging for a further study in which more symmetries that could be fit in our biological model will be examined, providing extra information about the myosin structure alterations due to aging. Our future goal is the application of PSHG microscopy for the investigation of muscle diseases, studying changes in the structure of myosin molecules during the disease progression.
Language Greek
Issue date 2021-07-28
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Graduate theses
  Type of Work--Graduate theses
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