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Glycerolipids and carotenoids in microalgae: the implications in ecophysiology and applied phycology
Střížek, Antonín ; Nedbalová, Linda (advisor) ; Brányiková, Irena (referee) ; Barreira, Luísa (referee)
Lipids are basic biomolecules found in all organisms. They have a key function as structural molecules forming cell membranes, and, in the form of fats and oils, energy is also stored. There are a huge number of lipid types that have other functions, for example, in cell signaling, enzyme support, protection against stress, and others. Microscopic algae are the main primary producers in both freshwater and marine ecosystems. Therefore, algal biosynthesis has a fundamental effect on the trophic networks of aquatic ecosystems and ultimately on humans. The environment affects the ecophysiology of algae, which is reflected in their biochemical composition, i.e. in the composition of their lipids. This work is focused on two groups of lipids, namely glycerolipids, which consist of fatty acids, and carotenoids, which are photosynthetic pigments with antioxidant and photoprotective properties. In these groups of lipids, the target substances were further selected, namely polyunsaturated fatty acids and the carotenoid fucoxanthin belonging to xanthophylls. These substances are important not only in the ecophysiology of algae, but they are valuable substances that have positive effects on the human organism and, with the help of optimized cultivation, could be obtained from algae for industrial production...
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Carotenoid Excited State Processes by Femtosecond Time-Resolved Pump-Probe and Multi-Pulse Spectroscopies
WEST, Robert G.
This Ph.D. thesis is an exploration of carotenoids by ultrafast, time-resolved absorption spectroscopy to investigate their complicated relaxation processes, means of energy transfer, and dependence on structure. The introduction begins with an overview of carotenoids, intended for the reader to appreciate their importance and their complexity as revealed by decades of research in carotenoid photophysics. To understand the primary concerns of this research field, the reader is guided through basic theory of energetic processes, the experimental method, and methods of analysis. The main body of the text is the Research Chapter, containing four sections, each describing research using varied ultrafast transient absorption spectroscopies on carotenoids in solution and when bound to a host protein. Section 2.1 concerns an equilibration phenomenon in the lowest excited state of the carotenoid fucoxanthin in various solutions and temperatures by a multi-pulse transient absorption method. The same method is applied to fucoxanthin in a host antennae protein of the pennate diatom Phaeodactylum tricornutum to investigate the function of the equilibration in energy transfer to Chlorophyll a in Section 2.2. The next two sections regard the effect of carotenoid structure on its relaxation dynamics. Section 2.3 investigates the effect of the non-conjugated acyloxy group of two fucoxanthin derivatives in various solvents. Here, one of the energetic states involved in the equilibrium mentioned above is seen drastically affected. Lastly, Section 2.4 investigates alloxanthin, a carotenoid with an unusual pair of carbon-carbon triple bonds. Their effect on the conjugation is evaluated based upon the molecules' decay dynamics. A general summary and conclusion is provided at the end.
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