Lecturer: Assaf Amitai
Abstract:
Biological phenomena can sometimes be explained using simple physical models, rather than the detailed description of their molecular components.
In the first part of my talk, I will describe one of the puzzles surrounding HIV. HIV has only a few spikes (proteins required for entry into the host cell) on its surface, in contrast to almost all other known viruses, which have many. This unique feature of HIV has defied explanation since it was first discovered. I will show that spike density can determine the strength of the immune response against the virus. This imposes evolutionary constraints that led most viruses to develop very high spike density while HIV, because of its unique impact on the immune system, evolved to be a low spike density virus.
In the second part of the talk, I will discuss recent developments in polymer models describing the motion of chromatin, which is composed of DNA and its compacting proteins. The biophysical description of chromatin can now be inferred by tracking its motion with microscopy methods. I will show how this approach was applied to understand the mechanism behind chromosomes’ motion during the repair of double-stranded DNA breaks.