PHOTOBIOPHYSIC AND PHOTOBIOLOGY
Learning outcomes of the course unit
During the course, the students will achieve fundamental concepts about the interaction of light with living matter and a deep knowledge of specific topics dealt during the lessons. In particullar of the new photoreceptor-based technologies in biophysics, biomedicine an biotechnology.
The students will learn to identify the best methodologies suitable to understand the structure and function of biological photoreceptors. They will learn to evaluate the experimental results obtained during the lab experiences and to carry on experiments with a certain degree of autonomy.
During the course the students should achieve:
a. critical ability to judge the most suitable methods to analyze a photobiophysical and photobiological phenomenon;
b. ability to draw conclusions on studied phenomena, starting from the analysis of topics dealt with during lessons
c. ability to identify unclarifies aspects of a phenomen and to suggest further experiments.
Basic chemistry and biochemistry. Introduction to Biophysics.
Course contents summary
Object of the course is the study of interactions between light and living matter, mediated by dedicated macromolecular systems (photoreceptors), 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), allows 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
Articles ditributed during the lessons; Slides from professor
Photobiology : The Science of Light and Life (Third Edition) : Springer (e-book, free-of-charge, ask the professor)
The course is sub-divided in 28 h hours of lessons (4CFU) + 24 h (2 CFU) of Labs experiences and seminars on selected topics
Assessment methods and criteria
The exam is made of a written part (questions and report on lab's experiences) + an oral seminar on a topic of choice. The final mark is the average between written and oral part.