Interdisciplinary seminar

[Ugo Bruzzo]

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INTERDISCIPLINARY LABORATORY FOR ADVANCED  STUDIES
MATHEMATICAL PHYSICS SECTOR
FUNCTIONAL ANALYSIS SECTOR
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As the first event of the activity "MATHEMATICS AND BIOLOGY",
Professor Luciano BOI (from  Ecole des Hautes Etudes
en Sciences Sociales, Centre de Mathematiques, Paris)

will give a talk entitled

WHEN TOPOLOGY MEETS BIOLOGY FOR LIFE:
INTERDISCIPLINARY REMARKS ON THE WAY
FORM MODULATES FUNCTION

on Friday, March 2,  at 2:30 pm in Room D
(SISSA, basement, Main building).

Abstract: Our understanding of fundamental epigenetic phenomena make
necessary to acknowledge that the true carrier of genetic information is
the chromosome rather than just DNA. Indeed, the chromatin structure
appears to harbor metastable key features determining the intrepretation
of genetic information. This organization layer need to be understood 
and
integrated with the organization layer of the genome sequence to model
genetic networks properly. In this manner, we will advance our global
understanding of the way the information contained in the genome is
interpreted by the cell.

Our presentation is aimed to describe some aspects of the way in which,
first, the two strands of DNA must be continuously unlinked during
replication, and second, chromatin is topologically condensed inside the
cells of organisms with nuclei. Three families of huge ATP-powered 
enzymes
– helicases, type-2 topoisomerases, and condensins – contribute to the
ordrerly unlinking of DNA and to the chromosome segregation in vivo. In
this process, two steps seem to be very fundamental. For replication to
occur, the DNA must be decondensed. Helicases unwind DNA creating (+)
supercoils (i.e., twists) and precatenanes which are rapidly removed by
topoisomerases. Type-2 topoisomerases actvely remove all DNA
entanglements. Then, the organized recompaction by condensins and
supercoiling are essential for chromosome partitioning. The chromosome
must, indeed, be folded into topological domains. Besides, we stress 
that
chromosome need to be topologically remodeled in order the genetic 
events
and the cellular process to be performed. Finally, chromatin structure 
and
chromosome conformation are dynamic and complex and exert profound 
control
over gene expression and other fundamental cellular processes.