CELLULAR BIOPHYSICS
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- Versione italiana
- Academic year
- 2021/2022
- Teacher
- GIORGIO RISPOLI
- Credits
- 6
- Curriculum
- Biologia molecolare e cellulare
- Didactic period
- Primo Semestre
- SSD
- BIO/09
Training objectives
- Biophysics is a highly interdisciplinary science because it applies the approaches and methods of physics to study biological systems at all scales of organization, from molecular to organismic and populations. Spanning the distance between the complexity of life and the simplicity of physical laws is the challenge of biophysics, whose goal is therefore to look for principles that describe patterns in life with math and physics. This approach is the most powerful way to gain insights: if the principles are powerful, they make detailed predictions of the biological process under study in “normal” and “pathological” conditions, which can be tested. This allows, for instance, developing new biomimetic technologies and informed therapies.
This course focuses on the most advanced topics of Biophysics and the most recent experimental methods to tackle them, therefore some arguments will be updated during the academic year on the basis of the most recent discoveries. Since the nervous system is the most complex (and for me the most fascinating) object of the universe, the course will focus on its mechanism and how it interfaces with the body and the external world. Moreover, the brain is an extraordinary study model because the notions learned in this course will allow the student to understand not only how the neurons and their connections work, but also how a multitude of other cellular systems work, since many neuronal mechanisms are ubiquitous. The student will be continuously stimulated to UNDERSTAND the mechanisms working in the biological systems rather than memorize, for instance, the names of the proteins that constitute them. Another course objective is to understand the functioning principles of the instruments used in the most advanced biophysics laboratories. Prerequisites
- Although there are no prerequisites, it is better that the student possesses the following knowledge base, which will be shortly recalled during the course:
Elementary concepts of physics, in particular electromagnetism;
Elementary concepts of chemistry;
Elementary concepts of calculus;
Animal cell biology. Course programme
- INTRODUCTORY NOTES (4 hours)
What is Biophysics? The study of the nervous system with Biophysics. The brain. Specialized areas and interfacing with external devices (i.e. robotic arms, artificial retinae). Performances of natural and artificial nervous systems. Order of magnitudes. Feedback and homeostasis.
BASIC MOLECULAR STRUCTURES AND LAWS (6 hours)
Water structure. Salt solvation. Molecular structure of lipids, proteins and nucleic acids. “Spontaneous” synthesis of aminoacids and nucleic acids in primordial planets. Recall of electricity: ionic and electronic conduction, electric potential, current, power and resistance. Measurement of current intensity. Conductors and insulators. Ohm’s law, resistivity. Physiologic ionic concentrations. Protein structure in membrane and in solution. hydropathicity diagrams. Nernst and Goldman-Hodgkin-Katz potential.
GENERATION AND PROPAGATION OF NERVOUS SIGNALS (6 hours)
Ligand-, voltage-, mechano-, light-, temperature-dependent channels and selectivity. Channelopathies. Graded potential, action potential, frequency coding, and synaptic transmission. Excitatory, inhibitory, ionotropic, and metabotropic synapses. G-protein enzymatic cascades. Spatial and temporal integration of synaptic signals. Effect of psychotropic drugs.
IONIC CHANNELS AND RECORDING OF THEIR ELECTRICAL ACTIVITY (7 hours)
AgCl electrode and membrane potential recording. Voltage-clamp. Na and K current isolation: the local anesthetics. Hodgkin-Huxley model. Saltatory conduction. Patch-clamp recordings. Single channel events and comparison with the macrocurrents.
FLUORESCENCE IMAGING (5 hours)
Electric, magnetic and electromagnetic fields. Sound and electromagnetic waves: frequency, wavelength, propagation speed, and amplitude. Synchrotron radiation. Fluorophores: excitation and emission wavelengths. Calcium imaging.
STRUCTURE/FUNCTION RELATIONSHIP OF MEMBRANE TRANSPORTERS (6 hours)
Molecular structure of the ligand- and voltage-dependent channels. 6TM, 4TM and 2TM topologies of K channels. Molecular structure, ionic transport and selectivity of the KcSA channel. Expression of cDNA or mRNA of ionic channels and aquaporins in oocytes. Uniports, symports, and antiports. Specificity, saturation and competition. Facilitated diffusion. Molecular models of transport: flip-flop. Active primary transports: ABC-, F-, V-, A-, and P_ATPase. Structure-function relationship of P- and V-ATPases. Secondary transporters: LeuT, MFS, NhaA molecular structure.
SENSORY TRANSDUCTION EXAMPLES: VISION, HEARING, BALANCE, OLFACTION, AND TASTE (8 hours)
Visual perception. Eye, retina, rod and cones. Phototransduction cascade and its calcium regulation. Antibacterial peptides and viroporins studied with rods. Mechanotransduction. Hair cells and lateral line of fishes and amphibia. Internal ear. Semicircular canals, utriculus, sacculus, mechanical amplification and cochlea. Basilar membrane and Fourier Analysis. Inner and outer hair cells. Tuning and adaptation in outer hair cells. Vomeronasal and olfactory receptors. Glomeruli and olfactory bulb. Odor perception coding. Olfaction enzymatic cascade. Gustatory papillae and butons. Salt, bitter, acid, umami and sweet transduction mechanism.
NEURONAL MASS RECORDINGS AND ADVANCED BIOPHYSICAL TECHNIQUES (6 hours)
Signal and transducers. Recording of analogical signals. Sampling theorem. Quantization. Binary code of digitized signals. Bit rate. Digital to analog conversion. Recording of a neuron ensamble transfected with calcium sensitive dyes or with voltage sensitive dyes. Light sheet microscopy. Super-resolution microscopy: deterministic (STED and RESOLFT) and stochastic (PALM). Static and dynamic tissue imaging: PET, fPET, TAC, NMR e fNMR; temporal and spatial resolution; contrast medium. Didactic methods
- The course comprises 48 hours of lecture (6 credits). The lectures are held on a weekly basis in classroom with the aid of Power Point slides, computer simulations, movies and digital animations. All the mathematical proofs will be carried out with the aid of a tablet connected to the classroom projector (virtual blackboard) and the equations are then illustrated with graphs and simulations by using the Mathcad platform. All the proofs and the sketches drawn on the virtual chalkboard are finally saved in files that will be uploaded, together with all the computer material used in the lecture and the lecture videorecording on the didactic platform FAD (Frequenza A Distanza: http://icdl.unife.it/did/). Some instruments and optical devices are shown in the classroom and given to the students for "hands-on" practice; the examination questions relevant to the arguments explained are given at the end of each lecture. The last four hours of lecture are dedicated to the review of the main subjects of the program.
Learning assessment procedures
- The exam objective is to assess how much the student achieved the training objectives described above. The evaluation is expressed in marks out of thirty (minimum score: 18). The exam consists in a written or oral (student's choice) answer to six questions randomly chosen among the ones introduced at the end of each lecture. The answers are judged on the basis of their content and the language clarity; the maximum score is 5 points for each answer. If the Covid-19 emergency provisions will continue, the exam will be kept online on Google Meet Grid
Reference texts
- It will be followed the text:
Fisiologia e biofisica delle cellule, a cura di V. Taglietti e C. Casella – Edises, 2015
that will be integrated, in its E-book form, with all the computer material described above. Some parts of this book will be also extended and other parts will be condensed in respect to its original version; the original and modified online version of this book will be available to the students that will buy the printed version.
Other useful texts for consultation:
Fisiologia - Molecole, cellule e sistemi - a cura di Egidio D'Angelo, Antonio Peres - Edi.Ermes, Milano - Volume I: Fisiologia molecolare e cellulare; Volume II: Funzioni d'organo e integrazione sistemica.
Bertil Hille – Ionic channels of excitable membranes – Third Edition – Sinauer
