1. Scalability : a statistical mechanics perspective on gene regulation and expression
Alessandro Giuliani

2. Scalability: a refresher
A scalable system displays behaviours dependent on the presence of an
ensemble and not directly derivable from microscopic properties of the single
elements. A portion sufficiently large has the same properties
of the whole system.

3. An highly connected system displays scalable properties if has the possibility of establishing long range correlations

4. Local properties have a general origin General properties come from local correlations

5. At odds with a road map, in which the block of a road with an high capacity cannot be overcame by the deviation of traffic on a narrow road, metabolism seems to be only dependent of topology: no lethal purely kynetic mutants.

16. The citokyne response is the ‘local’ portion of the network response, that can
be elicited only when Toll-like receptor system is active.
The genome-wide scalable response is the ‘whole netowrk resonant’ response
that is elicited even when Toll-like receptor system is out of work

18. The correlation computed on the entire profile of micro-RNA between
progenitor (CD34) and different lineages decays monotonously in time.
This behavior is exactly the same with a much smaller random set of
probes: scalability !

21. step1 step2 step3
0,0552 0,0928 0,1619 e-mk
0,0678 0,1145 0,1537 e-g
0,0747 0,1269 0,1750 e-mo
0,0260 0,0653 0,1192 g-mk
0,0159 0,0496 0,0546 g-mo
0,0289 0,0808 0,1413 mo-mk

23. Rugged Landscapes

24. Conclusions:
Biological systems, at every observation scale, display a wide spectrum
of behaviours from the extreme specificity (local actions) to scalability (general
effects).
Network paradigm allows to rationalize both specificity and scalability in terms of
attacks to crucial nodes and fault tolerance to random errors.
3. The single cell is not necessarily the place of ‘definitive explanations’ in biology.
Many macroscopic very reliable phenomena ask for a explanation at the
population level: ecology in a plate.
4. The consideration of cell lines phenotypes as attractors of an high dimensional
systems asks for a different approach in pharmacological intervention with respect
to usual ‘target identification’ pharmacology.