PHOTOBIOPHYSIC AND PHOTOBIOLOGY
Learning outcomes of the course unit
Acquisition of knowledge of fundamental concepts about light-biological matter interaction.
Learning of biophysical methods emnployed in the study of structure, function and dynamics of photoreceptors.
Knowledge of the most important applicative aspects of biological photoreceptors
Course contents summary
Object of the course is the study of interactions between light and living matter, mediated by dedicated macromolecular systems (photorecpetors), of the associated phenomena, and of the varios and innovative applications based on newly discovered photoreceptor systems.
In many organisms, the presence of photoreceptors (that are integrated protein-chromophore systems), aloows a variety of photorepsonses, ranging from the conversion of light energy into chemical energy, to sensorial responses such as photomovements and visual processes. Recently, it also became evident that, in some cases, photoreceptors can regulate bacterial growth patterns, infectivity or virulence. Photoactive artificial or semi-artificial systems are employed in photomedicine and phototherapies, e.g. in the photodynamic therapy of cancer. During recent years, the discovery of novel photoreceptors, indeed natural photoswtiches, has allowed to start novel applications of biotechonological relevance, such as optogenetics and superresoltuion microscopies. All these aspects will be explained during the course, together with the biophysical techniques employed to study the photochemistry and the relationships among structure, function and dynamics of photoreceptors, as well as to elucidate the molecular and physical mechanisms eventually responsible for biological photoresponses.
1. Introduction and general aspects
1a The laws of photophysics and photochemistry; chromophores and excited states;
1b. Main measurement units employed in photobiology
1c. Photoreceptors: energy converters and sensory photoreceptors
1d. Primary photophysical and photochemical reactions: energy transfer, charge transfer, isomerization, rearrangements of weak interactions.
2. Molecular mechanisms for light-chemical energy conversion:
2a. Light-driven ionic pumps
2b. Anoxygenic and oxygenic photosynthesis
2c. Enzymes for photoinduced DNA repar (photolyases)
2d. Thermodynamics of light-to-energy conversion
3. The molecular mechanisms of sensorial photoperception and signal transduction.
3a. Membrane opsins: visual processes, membrane channel, photomovements
3b.Soluble sensory photoreceptors: photomovements, growth patterns, responses to light-stresses, regulation of circadian rhythms.
3c: The "new world" of procarytic soluble photoreceptors: photosensory responses, light-regulated infectivity and virulence.
3d. Thermodynamics of light-to-signal conversion
4. Main biophysical methods used in the study of structure, function and dynamics of biological photoreceptors and their transient species: spectroscopic and structural techniques
5. Photomedicine and environmental photobiology
5a. Photosensitization mechanisms; phototherapies
5b. Evolution of photosensorial systems and of proteins for the photorepair of photodamages
6. Biotechnological and biophysical applications of photoreceptors
6a. Light-control of cell functions with native or engineered photoreceptors (optogenetics): photoreceptors as functional photoswitches
6b. Fluorescence microscopy with novel blue-light photoreceptors
6c. Superresolution microscopy with photochromic proteins: photoreceptors as optical photoswitches
7. Lab's experiments on selected topics
Selected articles (in english). Slides material.
Lessons(4CFU) + Lab's experiences (2CFU)
Assessment methods and criteria
Written exam + a lecture on a chosen topic. The final mark will be an average between the two parts.
During the course there might be lectures given by guest scientists on selected topics