Mario	Nicodemi - Universit&agrave; di Napoli <i>Federico II	
</i>
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Symmetry Breaking at X-Chromosome Inactivation #	
In 
female mammal embryo, X-Chromosome Inactivation is the vital 
process whereby each cell inactivates one, randomly selected X 
to equalize X products w.r.t. males. Such a chromosome wide 
stochastic regulation has attracted substantial interests 
because it is unknown how the X's undergo random, yet opposite 
fates. We proposed a possible physical explanation: a Symmetry 
Breaking mechanism, with a related set of new 'particles' 
involved and a corresponding phase diagram. Our model, 
confirmed by recent experiments in Harvard, describes how a 
'blocking' complex, responsible for protecting the bound X 
from inactivation, is self-assembled and why only one is 
formed out of many diffusible molecules, resulting in a 
spontaneous symmetry breaking in the binding to two identical 
X's.